AUTHORS. 
BEVAN, ARTHUR DEAN. 
GERRISH, FREDERIC HENRY. 
KEILLER, WILLIAM. 
McMURRICH, JAMES PLAYFAIR. 
STEWART, GEORGE DAVID. 
WOOLSEY, GEORGE. A 
TEXT-BOOK OF ANATOMY 
BY 
AMERICAN AUTHORS. 
EDITED BY 
FREDERIC HENRY GERRISH, M. D., 
Pkofessok of Anatomy in the Medical School of Maine, Bowdoin College. 
ILLUSTRATED WITH 950 ENGRAVINGS IN BLACK AND COLORS. 
LEA BROTHERS & CO;: 
PHILADELPHIA AND NEW 
1899. LIST OF AUTHORS. 
ARTHUR DEAN BE VAN, M. D, 
Professor of Anatomy in Rush Medical College in affiliation with the University of Chicago ; 
Surgeon to the Presbyterian and St. Luke’s Hospitals, Chicago, etc. 
FREDERIC HENRY GERRISH, A. M., M. D., 
Professor of Anatomy in the Medical School of Maine, Bowdoin College ; Consulting Sur- 
geon to the Maine General Hospital, Portland ; Fellow of the American Surgical Association ; 
sometime President of the American Academy of Medicine, etc. 
WILLIAM KEILLER, F. R. C. S. (Edin.), 
Professor of Anatomy in the Medical Department of the University of Texas, Galveston ; 
sometime Lecturer on Anatomy in the Edinburgh Medical School, etc. 
JAMES PLAYFAIR McMURRICH, A. M , Ph. D., 
Professor of Anatomy in the University of Michigan, Ann Arbor ; sometime Professor of 
Biology in the University of Cincinnati and Associate Professor of Animal Morphology in 
Clark University, etc. 
GEORGE DAVID STEWART, M. D., 
Professor of Anatomy in the University and Bellevue Hospital Medical College, New York 
City; Visiting Surgeon to Bellevue Hospital, etc. 
GEORGE WOOLSEY, A. 8., M. D., 
Professor of Anatomy and Clinical Surgery in the Cornell University Medical College, New 
York City; Visiting Surgeon to Bellevue Hospital, etc. CONTENTS, 
INTRODUCTORY. 
F. H. 
Gerrish:. 
Definition 17 
Names and Delimitations of Surface Parts . 21 
The Systems of Organs and their Functions • 29 
Organs removing Waste Matters ... 30 
The Vascular System 30 
Organs Supplying Nourishment .... 31 
Organs of Internal Secretion ...... 32 
PAGE 
Organs of Motion 32 
Framework Organs 32 
Organs of Relation 32 
Organs of Reproduction 33 
The Order of Topics . 33 
Methods of Study 33 
PAGE 
ELEMENTARY TISSUES. 
By F. 11. 
Gerrish. 
Cell-reproduction . 39 
Classes of Tissues. 
The Epithelial Tissues 41 
The Sustentacular Tissues 45 
White Fibrous Tissue 46 
Yellow Fibrous Tissue 47 
Areolar Tissue 47 
Adipose Tissue 49 
Gelatinous Tissue 50 
Adenoid Reticular Tissue 50 
Neuroglia 50 
Cartilaginous Tissues 51 
Osseous Tissue 52 
Dentinal Tissue 56 
The Liquid Tissues 57 
The Lymph 57 
The Blood _ 57 
The Muscular Tissues 58 
Plain Muscular Tissue 58 
Cedes. 
Cross-striped Muscular Tissue 59 
Cardiac Muscular Tissue 61 
The Nervous Tissues 62 
Membranes 64 
Serous Membranes 66 
Serous Membranes Proper 68 
The Lining Membrane of the Vascular 
System 68 
The Lining Membrane of Certain Cav- 
ities in Sustentacular Tissues .... 69 
The Lining Membrane of the Cavity of 
the Cerebro-spinal Axis • 69 
Synovial Membranes 69 
Articular Synovial Membranes .... 70 
Vaginal Synovial Membranes 70 
Bursal Synovial Membranes 71 
Mucous Membranes 71 
Cutaneous Membrane 74 
Glands 75 
EMBRYOLOGY 
Spermatogenesis 77 
Oogenesis 78 
The Early Stages of Development 79 
The Umbilical Cord and the Placenta ... 83 
Organs Derived from the Endoderm .... 86 
The Teeth and Salivary Glands .... 86 
The Branchial Clefts and the Structures 
Derived from them 87 
The Trachea and Lungs 88 
The Intestine and Mesenteries .... 88 
The Liver and Pancreas 90 
By J. P. 
McMurrich 
Organs Derived from the Mesoderm .... 91 
The Skeleton 91 
The Heart and Blood-vessels 93 
The Diaphragm .... 97 
The Lymphatic Vessels, the Spleen, and 
the Suprarenal Capsules 98 
The Muscular System 98 
The Excretory and Reproductive Organs 98 
Organs Derived from the Ectoderm .... 103 
The Nervous System 103 Entered according to Act of Congress in the year 1899, by 
LEA BROTHERS & CO., 
in the Office of the Librarian of Congress, at Washington. All rights reserved. 
WESTCOTT & THOMSON, 
ELECTROTYPERS, PHILADA. 
PRESS OF 
WILLIAM d. DORNAN. PHILADA. PREFACE. 
In their work as teachers of anatomy the authors of this volume have long 
felt the need of a text-book, which, while presenting the essential facts of human 
structure, judiciously avoids the unimportant and exceptional. They believe 
that the students in medical schools should neither be encouraged to depend 
upon pocket manuals nor be compelled to resort to encyclopaedias. Between the 
extremes of flavorless condensation and universal inclusiveness is a middle ground 
whereon should be marshalled in systematic array those portions of anatomical 
knowledge which, with our present information, are seen to be necessary pre- 
liminaries to the intelligent study of physiology, surgery, and internal medicine ; 
and from this field should be excluded the much greater collection of facts, which, 
however important to a work which designs to be exhaustive, have no known 
practical bearing, or only such possible application as will make them available 
for a useful purpose once or twice in a generation. 
The authors have endeavored to make a text-book which, as far as possible, 
shall stand in the place of a living teacher to the student—selecting from the 
vast accumulation of material those portions which are likely to be of actual 
service to the pupil in his subsequent study and to the practitioner in his clinical 
work, emphasizing the most important, striving to clarify obscurities, giving the 
greatest amount of help in the parts which are most difficult to learn, and illus- 
trating everything by all available methods. They may have slighted facts which 
others would have introduced; they certainly, as a matter of policy, have admit- 
ted many things which, in their judgment, are not essential to the student, except 
for the aid they afford him in meeting certain conventional demands, especially on 
the part of examiners, who may not have emancipated themselves from the tram- 
mels of tradition. 
The material facts have been gathered from the rich stores of information, 
which are recognized as the common property of science. No attempt is made 
to give credit to the discoverers, to whose efforts the present advanced state 
of anatomy is due ; and this omission is justified by two reasons: first, the 
impossibility of determining the original source in a majority of cases, and, second, 
the undesirability of loading a primary text-book with historical data which are 
not helpful in practical work. 
The various topics have been arranged on familiar lines, the ordinary divisions 
of systematic anatomy having been followed in the main ; but each author has 
set forth his subjects according to the methods which his experience has shown 
him to be profitable, and some of these will be seen to be different from (and, it is 
hoped, better than) those in ordinary vogue. Greater relative stress has been 
laid upon visceral structure, without neglect of the other branches; surface 
anatomy has received attention more in proportion to its usefulness than is usual; 
5 6 
PREFA CE. 
and the pictorial and diagrammatic illustrations (thanks to the remarkable liber- 
ality of the publishers) are phenomenally abundant and of striking artistic excel- 
lence. The method of direct labelling of the pictures, which has been proved to 
be so helpful to the student, has been applied wherever practicable. 
It is thought that the plan of giving the directions for dissection in a sepa- 
rate chapter will be appreciated as a marked convenience to the student in the 
laboratory. 
The nomenclature employed is that in general use among English-speaking 
anatomists. A few words, sanctioned by the approval of the Association of 
American Anatomists, or the Anatomische Gesellschaft, or both, have been used 
in preference to the customary, though less desirable, terms ; but, in every such 
case, the synonym is given, so that no confusion can arise. 
When a term, which has not been employed previously in the text, is intro- 
duced, its etymologic meaning is given parenthetically, unless its signification is 
manifest without such assistance. By this means a new and helpful aspect of 
the topic is often presented to the mind. 
The articles on the bones, the joints, and the veins have been written by Dr. 
Woolsey, those on the peripheral nervous system, the eye, the nose, and the skin 
by Dr. Keiller, that on embryology by Dr. McMurrich, that on the arteries by 
Dr. Bevan, that on the reproductive organs by Dr. Stewart, and the remainder 
by Dr. Gerrish. 
Portland, Maine, 21 March, 1899. PUBLISHERS’ NOTE. 
Perhaps the obvious magnitude of such an undertaking as the present may 
be connected with the fact, often observed, that although America has enriched 
medical literature with systematic treatises on all other branches, its anatomical 
instruction has been derived from foreign works. The creation of another volume 
would, however, be justified neither by this fact alone, nor by the growing and 
natural wish of American readers for works by home authors. The very multi- 
plicity of books on Anatomy proves that the science is advancing in discoveries 
of fact, relationship, and methods of presentation, and moreover that no volume 
fully satisfies all requirements. 
Xo effort has been spared by those responsible for this work to render it one 
in which Americans might take a justifiable pride, and which the fraternity of 
medicine abroad might equally welcome as a contribution to the advancement 
of a vital science. Text, illustration, and typography represent the best endeavors 
in their respective kinds. For many of the engravings individual acknowledg- 
ment has been made to TestuPs admirable Traite de VAnatomie, published by M. 
T)oin, of Paris, a work deserving wide recognition by English-speaking students. 
The series of illustrations in the present work is original to an unusual degree, 
and far more extensive than hitherto attempted. Colors have been abundantly 
employed, and particular care has been bestowed in engraving the labels of parts 
directly upon them wherever possible, whereby the student gains at a glance a 
knowledge of their names, position, and relations. 
7 LIST OF AUTHORS. 
ARTHUR DEAN BEVAN, M. D., 
Professor of Anatomy in Rush Medical College in affiliation with the University of Chicago ; 
Surgeon to the Presbyterian and St. Luke’s Hospitals, Chicago, etc. 
FREDERIC HENRY GERRISH, A. M., M. D., 
Professor of Anatomy in the Medical School of Maine, Bowdoin College ; Consulting Sur- 
geon to the Maine General Hospital, Portland ; Fellow of the American Surgical Association ; 
sometime President of the American Academy of Medicine, etc. 
WILLIAM KEILLER, F. R. C. S. (Edik.), 
Professor of Anatomy in the Medical Department of the University of Texas, Galveston ; 
sometime Lecturer on Anatomy in the Edinburgh Medical School, etc. 
JAMES PLAYFAIR McMURRIOH, A. M , Ph. D., 
Professor of Anatomy in the University of Michigan, Ann Arbor ; sometime Professor of 
Biology in the University of Cincinnati and Associate Professor of Animal Morphology in 
Clark University, etc. 
GEORGE DAVID STEWART, M. D., 
Professor of Anatomy in the University and Bellevue Hospital Medical College, New York 
City ; Visiting Surgeon to Bellevue Hospital, etc. 
GEORGE WOOLSEY, A. 8., M. D., 
Professor of Anatomy and Clinical Surgery in the Cornell University Medical College, New 
York City; Visiting Surgeon to Bellevue Hospital, etc. CONTENTS, 
INTRODUCTORY. 
F. H. Gerrish. 
Definition 17 
Names and Delimitations of Surface Parts . 21 
The Systems of Organs and their Functions . 29 
Organs removing Waste Matters ... 30 
The Vascular System 30 
Organs Supplying Nourishment .... 31 
Organs of Internal Secretion 32 
PAGE 
Organs of Motion 62 
Framework Organs 62 
Organs of Relation 62 
Organs of Reproduction 63 
The Order of Topics 63 
Methods of Study 63 
PAGE 
ELEMENTARY TISSUES. 
By F. H. 
Gerrish. 
Cell-reproduction 39 
Classes of Tissues. 
The Epithelial Tissues 41 
The Sustentacular Tissues 45 
White Fibrous Tissue 46 
Yellow Fibrous Tissue 47 
Areolar Tissue 47 
Adipose Tissue 49 
Gelatinous Tissue 50 
Adenoid Reticular Tissue 50 
Neuroglia 50 
Cartilaginous Tissues 51 
Osseous Tissue 52 
Dentinal Tissue 56 
The Liquid Tissues 57 
The Lymph 57 
The Blood 57 
The Muscular Tissues 58 
Plain Muscular Tissue 58 
Cells. 
Cross-striped Muscular Tissue 59 
Cardiac Muscular Tissue 91 
The Nervous Tissues 92 
Membranes 94 
Serous Membranes 96 
Serous Membranes Proper 68 
The Lining Membrane of the Vascular 
System 68 
The Lining Membrane of Certain Cav- 
ities in Sustentacular Tissues .... 69 
The Lining Membrane of the Cavity of 
the Cerebro-spinal Axis • 69 
Synovial Membranes 69 
Articular Synovial Membranes .... 70 
Vaginal Synovial Membranes 70 
Bursal Synovial Membranes 71 
Mucous Membranes 71 
Cutaneous Membrane 74 
Glands 75 
EMBRYOLOGY 
By J. P. 
McMurrich, 
Spermatogenesis 77 
Oogenesis 78 
The Early Stages of Development 79 
The Umbilical Cord and the Placenta ... 83 
Organs Derived from the Endoderm .... 86 
The Teeth and Salivary Glands .... 86 
The Branchial Clefts and the Structures 
Derived from them 87 
The Trachea and Lungs 88 
The Intestine and Mesenteries .... 88 
The Liver and Pancreas 90 
Organs Derived from the Mesoderm .... 91 
The Skeleton 91 
The Heart and Blood-vessels 9" 
The Diaphragm .... 97 
The Lymphatic Vessels, the Spleen, and 
the Suprarenal Capsules 98 
The Muscular System 98 
The Excretory and Reproductive Organs 98 
Organs Derived from the Ectoderm .... 103 
The Nervous System 193 
9 10 
CONTENTS. 
THE BONES 
G. Woolsey, 
General Considerations 113 
The Spine 115 
The Cervical Group 116 
The Thoracic Group 117 
The Lumbar Group 119 
The Sacral Vertebrae . 120 
The Coccyx 122 
The Spine as a Whole 123 
Ossification of the Vertebrae 124 
PAGE 1 
The Tibia 165 
The Fibula 157 
The Tarsal Bones 158 
The Astragalus 158 
The Calcaneum 159 
The Cuboid 159 
The Navicular 160 
The Cuneiform 160 
The Internal Cuneiform 160 
The Middle Cuneiform . . . . . . 161 
The External Cuneiform 161 
The Metatarsal Bones 161 
The Phalanges 162 
The Foot as a Whole .... 163 
Homologies of the Bones of the Two 
Extremities 164 
PAGE 
The Thorax. 
The Sternum .126 
The Bibs 127 
The Costal Cartilages 129 
The Thorax as a Whole 130 
The Clavicle 131 
The Scapula 133 
The Humerus 135 
The Ulna 137 
The Radius 139 
The Carpal Bones 140 
The Scaphoid 141 
The Semilunar 141 
The Cuneiform 141 
The Pisiform 143 
The Trapezium 143 
The Trapezoid 143 
The Os Magnum 143 
The Unciform 143 
The Metacarpal Bones 144 
The Phalanges 144 
The Bones of the Upper Limb. 
The Skull. 
The Occipital Bone 165 
The Parietal Bone 168 
The Frontal Bone 169 
The Temporal Bone . 171 
The Sphenoid Bone 176 
The Ethmoid Bone 179 
The Bones of the Cranium. 
The Bones of the Face. 
The Maxilla, or Superior Maxillary Bone . 181 
The Palate-bone 183 
The Vomer 184 
The Inferior Turbinate Bone 185 
The Nasal Bone 185 
The Lachrymal Bone 186 
The Malar Bone 186 
The Mandible, or Inferior Maxillary Bone . 187 
The Hyoid Bone 189 
The Skull as a Whole .... 190 
The Sutures 190 
The Exterior of the Skull 190 
The Interior of the Cranium 196 
General Morphology of the Skull ... 199 
Various Forms of the Skull 200 
The Bones of the Lower Limb. 
The Hip-bone 146 
The Ilium 146 
The Ischium 148 
The Os Pubis 149 
The Pelvis 150 
The Femur 151 
The Patella 154 
THE ARTICULATIONS. 
By G. 
Woolsey, 
General Considerations 203 
Kinds of Joints 204 
Kinds of Movement 205 
The Articulations of the Trunk and Head . 205 
The Articulations of the Vertebral Col- 
umn 205 
The Articulations and Ligaments be- 
tween the Atlas, Axis, and Occipital 
Bone 208 
The Articulations of the Thorax ... 211 
The Temporo-mandibular Articulation . 214 
The Articulations of the Upper Extremity . 216 
The Sterno-clavicular Articulation . . 216 
The Scapulo-clavicular Articulation . . 217 
The Shoulder-joint 218 
The Elbow-joint 221 
The Radio-ulnar Articulations and Liga- 
ments 223 
The Wrist-joint or Radio-carpal Articu- 
lations • 224 
The Carpal Articulations 225 
The Carpo-metacarpal and Intermeta- 
carpal Articulations 226 
Metacarpo phalangeal and Interphalan- 
geal Articulations 227 
The Articulations of the Pelvis 227 
The Articulations of the Pelvis with the 
Last Lumbar V ertebra 227 
The Sacro-coccygeal and Tntercoccygeal 
Articulations 228 
The Sacro-iliac Joint 228 
The Symphysis Pubis 229 CONTENTS. 
11 
PAGE 
The Articulations of the Lower Limb . . . 230 
The Hip-joint 230 
The Knee-joint 233 
The Tibio-fibular Union 237 
The Ankle-joint 239 
PAGE 
The Tarsal Joints 240 
The Tarso-metatarsal and Intermetatarsal 
Articulations 243 
Metatarso-phalangeal and Interphalan- 
geal Articulations 244 
THE MUSCLES. 
F. H. Gerrish. 
Muscles Moving the Digits of the Foot . ■ 316 
The Muscles of the Trunk. 
The Muscles of the Back 325 
Muscles in the Third Layer of the Back 325 
Muscles in the Fourth Layer of the Back 327 
Muscles in the Fifth Group of the Back 329 
The Muscles of the Abdomen 331 
The Muscles of the Thorax 334 
The Muscles of the Neck. 
Muscles of the Front and Side of the Neck . 337 
The Muscles of the Head. 
Superficial Muscles of the Head 342 
Muscles of Mastication 342 
Muscles of Expression 343 
General Considerations 245 
The Nomenclature of Muscles 248 
The Muscles of the Upper Limb. 
Movements of the Upper Limb 251 
Muscles Moving the Shoulder 253 
Muscles Moving the Arm 258 
Muscles Moving the Whole Forearm . . 263 
Muscles Moving the Outer Part of the Fore- 
arm 266 
Muscles Moving the Whole Hand 269 
Muscles Moving the Fingers 272 
Muscles Moving the Thumb 280 
The Muscles of the Lower Limb. 
Muscles Moving the Thigh 289 
Muscles Moving the Leg 301 
Muscles Moving the Whole Foot 308 
THE FASCIiE. 
F. H. Gerrish. 
The Superficial Fascia 349 
The Deep Fascia. 
The Fascia of the Head 350 
The Temporal Fascia 350 
The Masseteric Fascia 350 
The Buccinator Fascia 350 
The Cervical Fascia 351 
The Outer Cervical Fascia 351 
The Middle Cervical Fascia 352 
The Inner Cervical Fascia 352 
The Thoracic Fascia. . . , 353 
The Pectoral Fascia 353 
The Clavi-coraco-axillary Fascia . . . 354 
The Intercostal Fasciae 354 
The Fasciae of the Shoulder 354 
The Subscapular Fascia 355 
The Supraspinous Fascia 355 
The Infraspinous Fascia 355 
The Deltoid Fascia 355 
The Fascia of the Arm 355 
The Fascia of the Forearm 355 
The Posterior Annular Ligament . • • 356 
The Fasciae of the Hand 356 
The Anterior Annular Ligament . ■ 356 
The Palmar Fascia 356 
The Dorsal Fascia of the Hand .... 357 
Fascial Sheaths of Tendons in the Hand 357 
The Fasciae of the Back 358 
The Vertebral Fascia 358 
The Lumbar Fascia 358 
The Fasciae of the Abdominal Cavity . • • 359 
The Transversalis Fascia 359 
The Iliac Fascia 360 
The Pelvic Fascia 360 
The Obturator Fascia 360 
The Recto-vesical Fascia 
The Fasciae of the Perineum 361 
The Fasciae of the Hip and Thigh 362 
The Fasciae of the Leg 36_< 
The Fasciae of the Foot 364 
THE BLOOD-VASCULAR SYSTEM. 
THE HEAET. 
F. H. Gerrish 
The Arteries 
The Capillaries 3/7 
The Veins 377 
Descriptive Anatomy of the Heart .... 365 
The Pericardium .... 373 
The Physiological Anatomy of the Blood- 
vessels 374 12 
CONTENTS. 
THE ARTERIES. 
A. D. Be van. 
PAGE 
The Axillary Artery 412 
The Axillary Space 415 
The Brachial Artery .415 
The Ulnar Artery 417 
The Radial Artery 421 
The Descending Aorta 423: 
The Abdominal A orta 426 
The Common Iliac Arteries 432, 
The Internal Iliac Artery 433 
The External Iliac Artery 433 
The Femoral Artery 439 
The Superficial Femoral Artery 440 
The Posterior Tibial Artery 446 
The Anterior Tibial Artery 450 
PAGE 
The Pulmonary Arterial System . . 379 
A Syllabus of the Systemic Arterial 
System 381 
The Aorta 383 
The Arch of the Aorta 383 
The Brachio-cephalic Artery 386 
The Left Carotid Artery in the Thorax . . 389 
The Common Carotids in the Neck .... 389 
The External Carotid Artery 392 
The Internal Carotid Artery 401 
The Subclavian Artery 404 
The Internal Mammary Artery 409 
The Thyroid Axis . 410 
The Superior Intercostal Artery 411 
The Triangles of the Neck 411 
THE VEINS. 
G. Woolsey. 
The Pulmonary Veins . . . 454 
The Systemic Veins .... 455 
The Veins of the Heart 455 
The Superior Vena Cava and its Tribu- 
taries 456 
The Brachio-cephalic Veins 457 
Veins of the Head and Neck 457 
Veins of the Neck 460 
The Venous Sinuses of the Cranium . . 463 
The Ophthalmic Veins 467 
The Emissary Veins 467 
The Veins of the Brain 467 
The Veins of the Upper Extremity .... 468 
The Superficial Veins of the Upper Ex- 
tremity 468: 
The Deep Veins of the Upper Extremity 470 
The Veins of the Thoracic Wall . . . 470 
The Azygos Veins 471 
Veins of the Spine 472: 
The Inferior Vena Cava and its Tributaries . 474 
The Common Iliac Veins 476 
The External Iliac Veins 477 
The Portal System of Veins 477 
The Veins of the Pelvis 479 
Veins of the Lower Extremity 481 
Superficial Veins of the Lower Extremity 481 
Deep Veins of the Lower Extremity . . 482 
THE LYMPHATIC SYSTEM. 
F. H. Gerrish. 
The Lymph-vessels .... 484 
Lymph-nodes and other Lymphadenoid 
Structures 487 
Lymph-nodes 487 
The Nodes of the Head and Neck 489 
The Nodes of the Upper Limb 492 
The Nodes of the Lower Limb 493 
The Nodes of the Thorax 495 
The Nodes of the Abdomen 497 
THE CEREBRO-SPIXAL AXIS. 
General Considerations 499 
The Cavity of the Cerehro-spinal Axis . . - 501 
The Walls of the Cerehro-spinal Axis . . . 505 
A Diagrammatic Description of the Brain . 506 
The Cerebrum 509 
The Surface of the Cerebrum 509 
Delation of the Principal Lobes to the 
Parts of the Lateral Ventricle . . . 517 
Situation of the Lobes in the Cranium . 517 
The Callosum 517 
The Fornix 520 
The Anterior Commissure 522 
The Septum Lucidurn 522 
The Caudate Nucleus 524 
The Lenticular Nucleus 525 
The Claustrum 525 
The Amygdaloid Nucleus 526 
The Velum Interpositum 526 
F. H. Gerrish. 
The Region of the Third Ventricle—The 
Thalamencephalon 531 
The Thalami ' 532 
The Internal Capsule 537 
The Mesencephalon 538 
The Region of the Aqueduct 538 
The Epencephalon 540 
The Pons 540 
The Cerebellum 541 
The Oblongata 545 
Internal Structure of the Oblongata . . 547 
The Lemniscus 550 
The Fourth Ventricle 550 
The Spinal Cord 552 
The Membranes of the Cerebro-spinal Axis . 557 
The Membranes of the Brain 558 
The Membranes of the Spinal Cord . . 561 CONTENTS. 
13 
THE NERVES. 
W. Keiller 
PAGE 
The Thoracic Nerves 619 
The Lumbar Nerves ' 622 
The Lumbar Plexus 622 
The Iliohypogastric Nerve 623 
The Ilioinguinal Nerve 624 
The Genitocrural Nerve 624 
The External Cutaneous Nerve .... 624 
The Anterior Crural Nerve 624 
The Obturator Nerve 626 
The Accessory Obturator Nerve .... 626 
The Sacral and Coccygeal Nerves 627 
The Sacral Plexus 628 
The Pudic Nerve 631 
The Great Sciatic Nerve - • 631 
The Internal Popliteal Nerve 632 
Posterior Tibial Nerve 633 
External Popliteal or Peroneal Nerve • 636 
Fourth and Fifth Sacral and the Coccy- 
geal Nerves 638 
The Sympathetic Nerves. . • 639 
The Sympathetic in the Neck ■ 642 
The Thoracic Portion of the Gangliated 
Cord 644 
The Lumbar Portion of the Gangliated 
Cord 646 
The Sacral Portion of the Gangliated Cord . 648 
PAGE 
The Cerebro-spinat Nerves . . 563 
The Cranial Nerves 565 
The First or Olfactory Nerve 567 
The Second or Optic Nerve 568 
The Third or Oculo-motor Nerve . . .571 
The Fourth or Trochlear Nerve ... 574 
The Fifth or Trifacial Nerve .... 574 
The Sixth or Abducent Nerve .... 585 
The Seventh or Facial Nerve ... 585 
The Eighth or Auditory Nerve .... 589 
The Ninth or Glossopharyngeal Nerve . 591 
The Tenth, Pneumogastric, or Vagus 
Nerve 592 
The Eleventh or Spinal Accessory Nerve 596 
The Twelfth or Hypoglossal Nerve . . 596 
The Spinal Nerves 598 
The Anterior Primary Divisions . . . 603 
Cervical Nerves 603 
Branches given off Above the Clavicle . 606 
Branches given off Below the Clavicle . 607 
The Musculo-cutaneous Nerve .... 608 
The Median Nerve 608 
The Small Internal Cutaneous Nerve. . 612 
The Internal Cutaneous Nerve .... 612 
The Ulnar Nerve 612 
The Circumflex Nerve 613 
The Musculo-spiral Nerve 614 
THE ORGANS OF THE SPECIAL SENSES. 
THE SKIN 651 
By W. Keteler. 
Nails and Hairs 655 
The Sebaceous Glands 658 
The Sweat-Glands 659 
THE TONGUE 660 
By F. H. Gerrish. 
Other Organs of Taste .......... 662 
THE NOSE 663 
By W. K either. 
The Nasal Cartilages 664 
The Nasal Fossae 664 
Cavities Opening into the Nasal Fossae . 666 
THE EAR 668 
By F. H. Gerrish. 
The Internal Ear or Labyrinth 668 
The Membranous Labyrinth 668 
The Osseous Labyrinth 672 
The Middle Ear or Tympanum 674 
The External Ear 677 
THE EYE 680 
By W. Keit;ler. 
The External or Fibrous Tunic 682 
The Sclerotic 682 
The Cornea 682 
The Middle or Vascular Tunic 683 
The Choroid 684 
The Ciliary Zone 684 
The Iris . . . , 685 
The Inner or Nervous Tunic 680 
The Vitreous 689 
The Lens ~ 689 
The Aqueous 689 
The Muscles of the Eyeball 690 
The Superficial Appendages of the Eye ■ ■ 691 
The Eyelids 691 
The Conjunctiva 693 
The Lachrymal Gland 694 
THE ORGANS OF DIGESTION 
F. H. Gerrish. 
The Soft Palate JOO 
The Teeth 
Sets of Teeth V 
The Gums £O7 
The Tongue 
The Extrinsic Muscles of the Tongue ■ 709 
General Considerations 695 
The Mouth 698 
The Lips 699 
The Cheeks 699 
The Hard Palate 699 14 
CONTENTS. 
PAGE 
The Pharynx 710 
The Tonsils 711 
The Gullet 712 
The Abdominal Cavity 713 
Regions of the Abdomen 714 
The Stomach 715 
The Small Intestine ... 717 
The Duodenum 721 
The Jejuno-ileum 723 
The Large Intestine. . . . 724 
The Caecum 727 
The Appendix 728 
The Colon . 728 
The Ascending Colon 729 
The Transverse Colon 729 
The Descending Colon 729 
The Sigmoid Colon 730 
The Rectum 732 
The Anal Canal 734 
Glands Accessory to the Alimentary 
Tube. 
The Salivary Glands 734 
PAGE 
The Parotid Gland 735 
The Submaxillary Gland 735 
The Sublingual Gland 736 
The Pancreas 736 
The Liver 738 
Physiological Anatomy of the Liver . .738 
A Typical Lobe 738 
Arrangement of the Vessels 739 
The Form of the Liver 740 
The Surfaces of the Liver 741 
Borders of the Liver 744 
The Extremities of the Liver ... . 744 
Tunics of the Liver 744 
Supports of the Liver . 745 
Vessels of the Liver 745 
The Bile-ducts 746 
The Gall-bladder . . 746 
The Peritoneum 748 
Mesenteries 748 
Omenta 749 
Ligaments 750 
General View of the Peritoneum 750 
Reti’operitoneal Fossae 753 
THE ORGANS OF RESPIRATION. 
F. H. Gerrish. 
Physiological Anatomy 755 
The Trachea .... 757 
The Bronchi 758 
The Bronchia 758 
Minute Anatomy of the Lungs 759 
Gross Anatomy of the Lungs 762 
The Pleurae 765 
The Larynx 767 
The Cartilages of the Larynx 768 
The Ligaments of the Larynx .... 769 
The Muscles of the Larynx 771 
The Lining of the Larynx 773 
THE URINARY SYSTEM. 
The Kidneys 777 
The Excretory Apparatus of the Kidneys . .784 
The Ureters . 784 
The Bladder 785 
F. H. Gerrish. 
The Urethra . 787 
The Female Urethra 788 
The Male Urethra 789 
THE DUCTLESS GLANDS. 
F. H. Gerrish. 
The Spleen 793 
The Thyroid Body 796 
The Thymus '. . 797 
The Suprarenal Capsules 798 
The Parathyroids 799 
The Carotid Glands 800 
The Coccygeal Gland 800 CONTENTS. 
15 
THE ORGANS OF GENERATION. 
PAGE 
The Male Organs of Generation. 
The Testicles 801 
The Vas Deferens . 807 
The Seminal Vesicles 808 
The Ejaculatory Ducts .' 809 
The Scrotum 809 
The Spermatic Cord 812 
The Penis 812 
The Prostate Gland 818 
The Bulbo-urethral Glands 820 
The Muscles of the Male Perineum .... 820 
The Anal Group 821 
The Genito-urinary Group 821 
G. D. Stewabt. 
PAGE 
The Female Organs of Generation. 
The Ovaries 822 
The Fallopian Tubes 827 
The Uterus 829 
The Vagina 835 
The Vulva 837 
The Mons Veneris 838 
The Labia Majora 838 
The Labia Minora 839 
The Interlabial Space 839 
Erectile Organs 840 
Glands 841 
The Muscles of the Female Perineum . . . 842 
The Mammary Glands 843 
RELATIONAL ANATOMY. 
F. H. Gerrish. 
Plane Sections 847 I 
Surface Anatomy 857 J 
Normal Skiagraphs 871 
PRACTICAL 
ANATOMY. 
F. H. Gerrish. 
Directions for Dissecting . . 883 
Division of the Cadaver . . . 885 
The Thorax and Upper Limb 886 
Thoracic Cavity 886 
Front of the Arm 886 
Front of the Forearm 886 
The Palm 886 
Back of Thorax and Upper Limb . . 887 
Back of the Arm 887 
Back of the Forearm 887 
Back of the Hand 887 
The Abdomen and Lower Limb 887 
The Abdomen 887 
Abdominal Cavity ■ • 888 
Abdomen Proper 888 
The Pelvic Cavity of the Male . . 888 
The Pelvic Cavity of the Female : 888 
The Male Perineum 888 
The Female Perineum 889 
Front of the Thigh 889 
Inner Side of the Thigh 889 
Front of the Lee: and Dorsum of the 
Foot 889 
Outer Side of the Leg 889 
Back of the Hip 890 
Back of the Thigh • 890 
Back of the Leg 890 
The Sole 890 
The Plead and Neck 890 
Cranial Region 890 
Inside of the Cranium 891 
Back of the Neck 891 
Side of the Neck 891 
The Face. . 892 
Temporal and Zygomatic Fossse . ... 892 
Mandibular Region 892 
Deep Parts of the Neck 892 
Prevertebral Region 892 
The Orbit 892 
The Back 893 A 
TEXT-BOOK OF AX ATOMY 
INTRODUCTORY. 
F. H. GERRISIT. 
Definition of Anatomy, and Divisions of the subject.—Names and Delimitations of Surface 
Parts.—The Systems of Organs, and their Functions.—The Order of Topics.—Methods 
of Study. 
ANATOMY is the science of organization. It treats of the structure of 
AY organized beings. Not all of the beings in the world can properly be said 
to have a structure. We may speak of the structure of a flower, however 
simple, but we never associate the idea of structure with a crystal. The flower 
has petals, and calyx, and stamen, and other parts, each differing in look, texture, 
strength, and use from all the rest. The crystal is of the same material and 
appearance throughout : it is a mass which is equally dense, equally strong, 
equally colored in one part as in another—it is homogeneous; that is to say, its 
physical qualities are evenly distributed. The flower is easily seen to have 
organs, each of which has its own peculiar office; the crystal has no organs 
whatever. The one is organized—it has a structure • the other is not organized 
—it has no structure. Therefore we may study the anatomy of a flower, but 
there is no anatomy of a crystal for us to study. 
Let us here draw a distinction between the words organized and organic. 
The first relates to anything which has organs—parts which are differentiated 
from each other; the second is applied to things which result from the vital 
activity of organized beings. Thus, caseine, which exists in milk and is the 
characteristic material in cheese, is organic, for it is a result of the activity of 
a living creature; but it is not organized, having no structure, one portion 
being exactly like every other. Many things—for example, Avater—are neither 
organized nor organic; they are inorganic. 
All organized beings belong to one or the other of tAvo great groups—plants 
and animals. The distinction may not be essential; indeed, there are creatures 
upon the dividing-line between these groups Avhose nature is not yet determined 
—perhaps they are plants, perhaps they are animals. But, although it may be 
impossible to give a definition which shall include all of either group Avithout 
taking in some belonging to the other, these terras are not in the least likely to 
mislead us. The study of the structure of plants is called vegetable anatomy, 
and is thus distinguished from animal anatomy, which has to do with the organ- 
ization of the members of the other group of creatures. 
Physiology is often used, carelessly, synonymously Avith anatomy, but they 
are absolutely distinct. Anatomy is the science of structure; physiology is the 
science of function. Anatomy teaches us Avhat organs a plant or animal has; 
physiology teaches us to what use these organs are put. Anatomy shows Avhat 18 
INTROD UCTOR Y. 
an organ is; physiology shows what an organ does. Anatomy may be, and 
usually is, studied upon the dead creature; physiology can be studied only upon 
the living—it requires organization in action. 
Of all animals, the human was the first whose anatomy was studied with 
great care. Naturally, men were more interested to know what they could about 
their own bodies than about those of other creatures ; and when they did inves- 
tigate the structure of the members of lower orders, it was to be expected that 
they would institute comparisons between the organs of the latter and those in 
themselves which seemed to correspond. Thus it came about that they called 
the science of the structure of all other animals comparative anatomy, to distin- 
guish it from the science of their own organizations, which is human anatomy. 
If they had begun their study of animal structure at the other end of the scale, 
taking first animals of the simplest organization and working up gradually 
through a series, each member of which was more elaborately constituted than 
its immediate predecessor, until they reached man, the term comparative anatomy 
would not be used in the sense in which it is usually employed. But, although we 
recognize the defects of their method, we must confess that in the same circum- 
stances we would doubtless have done precisely as they did. Now-a-days, how- 
ever, the student is counselled to begin with simple and easily understood struc- 
tures, in order to prepare himself for the readier comprehension of the more 
complex, and finally of the most intricate. The study of the anatomy of the 
lower animals is an admirable—indeed, the best—preparation for that of human 
anatomy. One who is familiar with the structure of one animal in the great 
group in which man belongs, as the cat, for example, will find human anatomy 
immensely simplified. But comparative anatomy, as a separate branch, has no 
right to a place in the course of study in a medical school, and only occasionally 
and incidentally will it be referred to in this book. 
Human anatomy is subdivided, according to the means employed in its study, 
into two great parts : gross or macroscopic anatomy, in which no aids to vision 
are employed, and minute or microscopic anatomy, in which the assistance of 
optical instruments is used. 
According to the method pursued in its study gross anatomy is subdivided 
into systematic and relational. Systematic anatomy, called also descriptive anat- 
omy, regards the body as made up of systems or sets of organs. For example, 
considering the human being from this point of view, we find that it has 
a nervous system (brain, spinal cord, nerves, etc.), a circulatory system (heart, 
blood-vessels, etc.), a digestive system (stomach, intestines, etc.), an osseous 
system (bones, etc.), a muscular system (muscles, etc.), a respiratory system 
(lungs, windpipe, etc.), an excretory system (kidneys, bladder, etc.), a reproduc- 
tive system (ovaries, testicles, etc.). Knowledge of the various organs comprised 
in each of these systems is essential to the practitioner of medicine and surgery. 
But if he knows each of these systems only in a separate and unassociated way, 
he is far from being equipped anatomically as he ought to be. He still needs 
to learn how each part of every system is related to each part of every other 
system, and particularly what are the relations of each object to all of the other 
objects in its neighborhood or region. In other words, he must know his 
anatomy not only from the systematic point of view, but from the relational. 
Other names given to this method of study are regional anatomy, because by it 
the body is divided into regions for investigation; topographical (from the 
Greek word meaning “place”), a term used by civil engineers to designate 
a survey in which the position of every part of the territory involved is deter- 
mined relatively to every other part; surgical, because operations cannot safely 
be performed without knowledge thus acquired; medical, because it is necessary 
to accurate diagnosis of disease of internal organs. 
Systematic anatomy is made possible by dissection, by which is meant the 
careful and delicate cutting apart of the various structures, so that they can be 
observed and studied. It is practised upon the dead body. Much of relational INTB OD UCTOB Y. 
19 
anatomy also can be acquired in this way; but a very modern method has 
revealed a multitude of facts in this connection which were previously unknown, 
and are incapable of demonstration by dissection alone. This new method is 
that of plane sections. The sections are made in the following manner : a body 
is frozen so hard that a saw, in cutting through it, encounters no more resistance 
in bone than in muscle. Cuts with a saw are made in any direction which one 
chooses, but the most common are the horizontal, the vertical sidewise (also 
called “ coronal ” or a frontal ”), and the vertical fore-and-aft (known also as 
“ sagittal ”). The cut having been made, the saw-dust is very carefully cleared 
away from the surfaces, and the relations of the parts which have been brought 
to view are studied. As an elevation of temperature above the freezing-point 
will impair the fixity of the specimens, and as it is manifestly out of the question 
to maintain such a degree of cold permanently or to study the specimens com- 
fortably during its continuance, it is usual to photograph them, or immerse them in 
a preservative fluid in flat vessels covered with plain glass, or to adopt both of 
these devices for continuing the study. Students are not expected to do this 
work, which involves great labor, skill, and, for interpretation of the appear- 
ances of the sections, a high degree of anatomical knowledge ; but they can avail 
themselves of the results of this method by studying the actual sections or casts 
of them in their medical schools, or, what is sometimes better because more intel- 
ligible, pictures of sections made from photographs and labelled in detail. 
Minute or microscopic anatomy deals with those features of structure which 
are too small to be recognized by the unaided eye. It can be studied only with 
the assistance of a microscope. A branch of microscopic anatomy is histology 
(the name coming from the Greek word for “ texture ”), which is the science 
of the tissues. But the name histology has been much used synonymously for 
microscopic anatomy, the whole getting its designation from a part, as in many 
other cases in our language. Histology is sometimes called general anatomy, 
because the tissues are distributed to all parts—are general to the various 
organs. 
A homely illustration will serve to make the difference between these various 
subdivisions of anatomy clear. We may use the word “ anatomy ” with refer- 
ence to artificial structures, as, for instance, the anatomy of a steam-engine or 
of a watch or of a house. Let us, then, regard a house from the points of view 
successively of the systematic anatomist, the topographic anatomist, and the 
histologist. The first of the trio considers the house as made up of sets of 
organs, a series of apartments devoted to alimentary purposes, as the kitchen 
and dining-room; another set used for sleeping—the bed-chambers; one for 
study—the library, and so on; a system of tubes conveying water to various 
parts of the establishment; another lot bearing illuminating gas to every room ; 
a third supplying steam or hot air for raising the temperature ; and still another 
carrying off liquid waste materials; large, vertical pipes by which injurious 
products of combustion are conducted away; a quantity of wires adapted to the 
conveyance of electricity for various purposes within the house, and a set of rods 
designed to keep electricity out of it. Thus he finds whatever organs go to com- 
pose a house, and describes each set by itself, so that a person who to 
know about any system of apparatus—as, for example, that used for heating 
or that for sewerage—can learn about it by consulting the record of the investi- 
gator’s observations. 
The topographic anatomist approaches the question of the structure of the 
house in an entirely different way. He examines the building by such means 
that, without actually cutting it into slices, he is able to make drawings which 
show just what these plane sections would display if they were made. He does 
not concern himself with any separate system of rooms or rods or pipes or wires, 
but he studies the relations which obtain between all of the objects which he 
sees in each of his imaginary sections. For example, he observes that the 
parlor is related to the cellar below, to a bed-chamber above, to a library behind, 20 
IN TROD VC TOR Y. 
to a corridor at one side, and a roofed piazza on two sides. He notes the electric 
wires, the gas- and steam- and water- and waste-pipes within the walls of 
the room, the chimney which projects into it, and the relations which these 
sustain to the room itself and to each other. He proceeds thus until every 
region of the house is investigated and mapped out, and when he has done all 
this one can get from his records a complete idea of the relations of every piece 
of the structure to every other. 
Finally comes the histologist, who, disregarding systems of organs and heed- 
less of the relations between various parts, looks only at the structural materials 
entering into the composition of the house; in other words, its tissues. He 
finds that the house is made up of stones, bricks, boards, beams, nails, slates, and 
many other things, which present to the eye definite forms by which they are 
recognizable. It may be that some one kind of these structural elements varies 
in shape and in other respects in different parts, as, for instance, the bricks, 
which are of one form, size, and smoothness in the outside wall, different in all 
of these respects in the inner wall, and unlike either of the other kinds in the 
fire-places; but they are all readily seen to belong in the same category. 
Each of these three methods of considering the house has its uses; each 
alone is seen to be inadequate to convey a comprehensive idea of the building. 
An architect employs all of them : he is, as regards houses, a systematic anatomist, 
a relational anatomist, and a histologist; he knows what the organs of a building 
are, how they stand in space with reference to each other, and of what textures 
they are constructed. For exactly the same reason every practitioner of medicine 
must be a human anatomist in all three of these ways. He finds one disease 
affecting a given system—as, for example, the alimentary—and therefore has to 
know the organs of this system as a continuous series; he meets with another 
disease involving, not a set of physiologically associated organs, but a number 
of parts which are related to each other in a geographical way, occupying a 
limited region, and consequently he needs to be acquainted with the organs 
or parts of organs belonging to half a dozen different systems. In either case 
ho may be unable to appreciate the condition of affairs if he is ignorant of the 
tissues entering into the composition of the structures which are invaded. 
The body may be considered anatomically from still other points of view. 
If it is in a state of health, the study of its structure is normal anatomy ; if it 
is in a condition of disease, pathological or morbid anatomy. When the organ- 
ization is studied with especial reference to function, we pursue the method of 
physiological anatomy. The consideration of the plan or model upon which 
organs are formed constitutes morphological anatomy; and as the discussion of 
such matters is attended necessarily with more or less of speculation, the 
synonyms philosophic and transcendental anatomy are often employed. The 
object which the investigator has in view determines the division of the subject. 
Thus, if he studies the body with the purpose of representing it in a pictorial 
or plastic way, it is artistic anatomy ; if his only intent is to acquire knowledge 
which will be especially serviceable in the practice of the healing art, it is applied 
or clinical anatomy. Practical anatomy is a name employed to indicate the study 
of the body by dissection. 
It will be understood, however, that we confine ourselves to human anatomy 
solely ; that we regard it only in its normal aspects ; that, unless otherwise speci- 
fied, the adult condition is assumed; and that we consider anatomy chiefly with 
a view to the interest which it must have for the student who desires to fit him- 
self for the work of the medical profession. This will involve the study of 
systematic, relational, and microscopic anatomy, and in the treatment of many 
topics all three of these methods will go along hand in hand. Frequently the 
physiological anatomy will be presented at the opening of a section, because it 
is so much easier to understand a machine if we enter upon its study with 
a distinct idea of the work which it is capable of performing, than if we have 
no notion of its function. NAMES AND DELIMITATIONS OF SURFACE PARTS. 
21 
The following tabulation will aid in recalling the principal points which have 
been made : 
{Vegetable 
. 
Animal 
Anatomy 
r Comparative (all 
lower animals) 
1 
I Human (man) 
f Gross, or Macroscopic 
1 Minute, or Microscopic 
I (Histology) 
j" Systematic, or Descriptive. 
I Relational, Topographic, 
( 'or Regional. 
NAMES AND DELIMITATIONS OF SURFACE PARTS. 
At the outset of anatomical study it is important to have the clearest possible 
conception of the limits set by nature or by convention to the various parts 
which will be referred to constantly in the following pages, and also to have for 
each of these parts a name which shall be used for that and for nothing else. 
All parts, even the minutest, have technical names, which are Latin in form, and 
almost all parts which are visible without dissection, and those which are brought 
into view by accident, have, besides the scientific, vernacular appellations—names 
given by non-medical people who never had a thought of knowing anatomy. 
The scientific name of a part is understood in every land where medicine is 
cultivated; the vernacular designation in one language is generally different 
from that in every other, and frequently essentially so. Thus, what we call 
“head” in English is “tete” in French, “ kopf ” in German, “testa” in 
Italian ; and the anatomist who is acquainted with no modern language but his 
own can understand only that one of these words which belongs to his native 
tongue. “ Caput,” however, means the same thing to English, French, German, 
and Italian, for all scientific men are supposed to know something of Latin, the 
language of scientific nomenclature. Only a small proportion of the names 
applicable to anatomical parts is included in the vocabulary of the common 
people, but anatomists generally use these in their writings ; for the suggestion 
of pedantry which inevitably would come from the invariable employment of 
the technical terms instead of the existing vernacular words would be almost 
intolerably offensive. Unfortunately, however, quite a number of these vernac- 
ular titles are used by anatomists with different significations from those which 
they have to the unscientific; and hence it seems necessary to explain what 
meaning we shall attach to these words, which have been familiar to us from 
the cradle. 
It may seem to some readers needless to undertake this enumeration and definition. _ But 
a large observation of medical students through many years has demonstrated that it is highly 
desirable to do exactly this thing. People of much more than ordinary intelligence and educa- 
tion rarely have any idea of the difference between the meaning which many a word has to 
medical men and that which is attached to it generally. When a surgeon hears through a non- 
medical source that a person has broken a leg or an arm, he simply gathers the impression that 
a fracture is supposed to have occurred in a lower limb in the one case and in an upper limb m 
the other case; but if leg or arm is mentioned by a medical man, he knows that the third 
segment of the lower extremity is meant in the first instance, and the second segment of the 
upper extremity in the second. “Wrist” to the laity means anywhere from the upper level 
of the palm to nearly halfway up the forearm; “hip” is used instead of “thigh,” mention 
of the latter, for some inexplicable reason, being at present considered even more indelicate 
than that of “leg,” for which polite usage has substituted “limb.” These few selections from 
a considerable number will serve, it is hoped, to justify the attempt which is here made in the 
interest of precision of language and of thought. 
In order to understand the application of the terms intended to designate the 
relation in space which different parts of the body sustain to each other, it is 
necessary to know what is regarded as the anatomical position. This is the erect 
attitude, with the palms of the hands turned to the front, and the soles of the 
feet horizontal—that is, facing downward. 
To the anatomist “ head ” (caput) means all of the mass which is balanced 22 
INTB OB UCTOB Y. 
on the neck, the front and lower portions being “ face ” (facies), the upper and 
back “ cranium,” the dividing-line between the two parts starting at the so-called 
root of the nose in the mid-line, and extending on each side beneath the over- 
hanging brows and downward and backward to the ear. But “ head,” in com- 
mon parlance, means at some times all that we have included, as in decapitation ; 
at others only the cranium, as in the use of the word headache. “Face” with 
the people embraces the anatomical face and also the anterior portion of the 
cranium ; a beautiful face would be considered desecrated if its picture showed 
nothing above the eyeballs. And yet “ face ”is often used in a more restricted 
sense than the anatomical, as when one speaks of faceache, meaning pain in the 
cheek region only. 
SINCIPUT 
FRONS 
PALPEBRA SUPERIOR. 
OCULUS- 
TEMPUS 
PALPEBRA INFERIOR— 
OCCIPUT 
NASUS r. 
ALA NASIS 
GENO-LABIAL SULCUS- 
PHILTRUM- 
_/) LABIUMV 
USUPERIUa 
MALA OR GENA 
OS- 
LABUJM ' 
\INFERIUS v 
MENTO-LABIAL SULCUS- 
/MENTUM 
[OR GENIUM; 
CERVIX OR 
COLLUM 
POMUM ADAM I 
Fig. I.—Side view of cranium and face. (F. H. G.) 
The cranium is subdivided (Fig. 1) into an anterior part, the “ forehead ” 
(frons) ; an upper, the “crown” (vertex or sinciput) ; a back, the occiput; and, on 
each side, the temple (tempus). There are no surface-markings by which these are 
absolutely delimited. At the lower portion of the temporal region is the flaring 
part of the ear, known by anatomists to be the least important division of the organ 
of hearing (auris), but thought by people commonly to be about all of it, and con- 
sequently named “ ear.” The forehead terminates below at the “ nose ” (nasus) in 
the middle line, and on each side of this, in an arched border, usually covered with 
short, crisp hairs, and called the “ brow ” (supercilium). In the face immediately 
beneath each brow is an “ eye ” (ocuius), that is, an eyeball or globe, shielded 
above by an “upper lid” (palpehra superior) and below by a “ lower lid” (pal- 
pebra inferior), their edges fringed with short hairs, the “ lashes ” (cilia). Be- 
tween the eyes and in the middle of the face, below their level, is the projecting 
part of the nose, which is all that is generally recognized as nose. This has 
on each side below an opening, presenting downward, the “nostril” (naris), 
guarded on the outer side by a flaring projection, the “wing of the nose” (ala 
nasi). What is commonly called the “ bridge of the nose,” a prominence caused 
by the nasal bones, has no technical designation. At a short distance beneath 
the nose is a transverse slit, to which, as well as to the cavity of which it is the 
opening, is given the name “ mouth ” (os). Above this aperture is the “ upper NAMES AND DELIMITATIONS OF SURFACE PARTS. 
23 
lip ” (labium superius), and underneath it the “ lower lip ” (labium inferius). Pop- 
ularly, the word month is often applied to the lips, as when a woman is said to 
have a pretty month—a comment which manifestly is not intended for the slit- 
like opening, and still less for the cavity behind it. (It may not be amiss to 
call attention to the fact that the Latin os, meaning a mouth, has oris for its 
genitive, and gives origin to our English oral; whereas os, meaning a bone, 
is ossis in the genitive, and thus stands behind our English osseous.) The upper 
lip extends vertically from the nose above to the free border below, and later- 
ally to the crease which courses down and out from the hind border of the 
wing of the nose, and is called the geno-lahial sulcus; the lower lip extends 
from its free edge above to a transverse crease, the mento-labial sulcus, which 
presents a downward concavity, and separates the lip from the chin. The 
middle portion of the upper lip projects farther downward than do the parts 
which bound it laterally, and its skin surface is marked by a somewhat tri- 
angular depression, the philtfum. The border of the skin of this lip describes 
a line which is a mark of beauty, and is called by artists the bow of Cupid. 
The “ chin ” (mentum, genium) is the central prominence which finishes the face 
below, in and near the mid-line. It is not distinctly separated from the cheeks. 
The main part of each lateral aspect of the face is the “ cheek ” (mala, gena), 
which presents a broad, quadrilateral expanse, bounded below by the inferior 
border of the lower jaw, behind by the vertical portion of the bone of this jaw, 
above by the lower margin of the orbit (the cavity lodging the eye) and by the 
ridge of bone running back from it, and in front above by the side of the nose, 
below this by the geno-labial sulcus, which separates the cheek from the upper 
lip. The outlines of the lower part of the face are determined largely by its 
framework, the inferior jaw-bone (mandihula), which, with its various attach- 
ments and coverings, constitutes the under jaw (maxilla inferior). The upper 
jaw-bone is the staging upon which the greater part of the central zone of the 
face reposes. On separation of the lips the “ teeth ” (dentes) are seen projecting 
beyond the “ gums ” (gingivee) in two arches with the convexities forward ; and 
on depressing the lower jaw a view of the cavity of the mouth is obtained. In 
its floor we see the muscular “ tongue ” (lingua) with its rough upper surface ; 
its roof is formed by the “ hard palate” (palatum durum), and behind is the 
“ soft palate ” (palatum molle) hanging like a short curtain over the base of the 
tongue. Between the two upright ridges to which the soft palate extends on 
each side is the “ tonsil ” (tonsilla, amygdala), and beneath the pendulous veil 
of the palate we can see a part of the rear wall of a cavity for which the laity 
have no name, but which we know as the pharynx. 
The “ neck ” (cervix, collum) connects the head and the trunk (Fig. 2). In 
front it extends from the level of the lower jaw to the u breast-bone ” (sternum) 
in the middle line and the “ collar-bone ” (clavicula) on each side. These bones 
can readily be felt through the overlying structures. Behind, in the middle line, 
the neck extends from the base of the cranium to the seventh segment of the 
back-bone or spine, the tip of which can be both felt and seen projecting beyond 
the plane of any of its fellows above. Between this segment (vertebra prominens) 
and the collar-bones—that is, at the sides—there is no clear demarcation of the 
neck from the trunk when the upper limbs hang passively : there is usually an 
unbroken slope from the head to the peak of the shoulder. But if the shoulders 
are raised straight upward, a crease is produced which sharply indicates the 
boundaries of the neck for two-thirds or more of the distance, and suggests the 
line for the remainder. In this attitude of hunched shoulders the neck rises 
like a column from a depressed base. Although not exact in every respect, this 
technical delimitation of the neck is vastly more definite, as well as more 
restricted, than that which is in popular vogue concerning women arrayed in 
what is known as “ full dress,” whose necks, varying at different times according 
to the dictates of fashion, may find their lower limits anywhere between the 
collar-bones and the nipples in front, and between the vertebra prominens and INTR O D UCTO 11Y. 
i CHEEK/ 
.MALA, 
CHEST OR 
~-NIPPLE 
MAMMILLA'S 
-HALO 
AREOLA^ 
THORAX 
BELLY OR 
NAVELi 
UMBILICUS 
ABDOMEN 
MONS 
x PUBIS^ 
PALM 
KNEE 
OUTER| 
RANKLE' 
\tarsus' 
MALLEOLUS EXTERNUB 
FIFTH DIGIT OR LITTLE TOE- 
[HEEL 
CALX] 
Imetatarsu^ 
DIGITUS QUINTUS, 
FOURTH DIGIT OR FOURTH TOE 
THIRD DIGIT OR THIRD TOE' 
SECOND DIGIT OR SECOND TOE' 
FIRST DIGIT OR GREAT'TOE 
‘DIGITUS SECUNDUS 
DIGITUS MINIMUS 
' DIGITUS QUARTUS 
'DIGITUS TERTIUS 
Tig. 2. Front view of a man in the anatomical position. On one lateral half the parts are labelled in English 
on the other in Latin. (F. H. G.) 
DIGITUS PRIMUS, HALLUX. POLLEX PEDIS NAMES AND DELIMITATIONS OF SURFACE PARTS. 
25 
the small of the back behind. The word “ throat ” has no anatomical equivalent. 
It is variously used to designate the front part of the neck, or the tonsils and 
adjacent parts of the soft palate, or the pharynx, or the organ of voice {larynx). 
High up on the neck in front is a hard protrusion, more prominent in men,than in 
women, caused by the thyroid cartilage of the larynx, and called “ Adam’s apple ” 
{pomum Adami) in playful celebration of the most noted and unfortunate gastro- 
nomic performance on record. The median portion of the neck behind is the 
“ nape ” {nucha). Just above the top of the breast-bone is often seen a little 
pit, esteemed a mark of beauty by artists, who have named it “ Diana’s pool.” 
The body proper, as distinguished from the entire organism, is known as the 
“ trunk ” (truncus), and presents two grand divisions, the upper of which is the 
“ chest ” {thorax), the lower the “ belly ” 
{abdomen). The superficial line of separa- 
tion between them is pronounced, and is 
made by the bones and cartilages which 
form the lower border of the thoracic cage, 
as the skeleton of the upper cavity is called. 
Sloping downward and outward from the 
lower part of the breast-bone, the boundary- 
line is continued backward at the sides, and 
then obliquely upward behind. But this 
surface marking is by no means an indica- 
tion of the relative size of the two cavities : 
it only shows the line along which is at- 
tached the base of a muscular dome, the 
diaphragm or midriff, whose central portion 
rises to the level of a point about halfway 
up the sternum, and shuts off the cavity 
of the thorax from that of the abdomen. 
Thus, the summit of the belly-cavity is 
rounded, presenting a marked convexity 
upward, and the base of the chest-cavity, 
into which the former rises, is correspond- 
ingly concaved. 
From the front of the chest of the adult 
female there projects a nearly hemispherical 
mass on each side (Fig. 3). This is the 
“breast” {mamma), the organ in which 
milk is formed. The valley between these 
hillocks is properly the “ bosom,” but this 
word is often used as synonymous with 
AREOLA- 
MAMMA 
MAMMILLA/ 
, MOMS VENERIS., 
VULVA- 
Fig. 3.—Front of torso of woman. (F. H. G.) 
breast. At about the central point of 
each mamma stands out the nipple or teat {mammilla, literally “ the little breast”), 
its base surrounded by a circular space which is distinguished by the darkness 
of its skin, and is called the areola (literally “the little area”) or the “halo.” 
The male has no milk-forming organ, but he has in the same relative situation 
upon the chest-wall slightly developed mammillae. These are good illustrations 
of a rule that the generative organs which are fully developed in one sex are 
aborted in the other, being represented in the latter by some little bulge or dimple, 
whose only use seems to be to suggest the narrow escape of its possessor from 
being of the opposite sex. 
The belly at its upper central part presents a shallow depression, popularly 
called the “ pit of the stomach,” but technically scrobiculus cordis, which literally 
means “the little pit of the heart.” This confusion of names arises from the 
physical (not the figurative) nearness of the heart and stomach, the one resting 
upon, the other lying underneath, the diaphragm, and both being in the region 
of this slight hollow. Farther down in the mid-line, and usually nearly on 26 
INTB OB UCTOB Y 
a horizontal drawn between the highest points of the haunch-bones, is an irreg- 
ular, puckered dimple, the “ navel,” called in Latin umbilicus, from umbo, the 
button in the centre of an ancient shield; so that we see that the childish name 
for the part—belly-button—has the sanction of a noble classical derivation. 
Following down in the middle line, we find at its lowest part an area which 
extends considerably sidewise, and is covered in the adult with crisp, curly hairs. 
This is the pubes. Behind the skin of the pubes the male has a little pad of fat, 
and the slight elevation which is thus produced is sometimes called mans pubis— 
that is, the mountain of the pubes. In the grown female there is so marked an 
accumulation of fat here as to make a very noticeable hillock, which is named 
mons Veneris (the mount of Venus), in honor of the Roman goddess of love. 
BUTTOCK 
BUTTOCK 
/ SCRCTUM 1 
Fig. 4.—The male perineum and surrounding parts. (After His.) 
Running obliquely upward and outward from the pubic region on each side is 
a crease which separates the trunk from the lower limb in front, and is called 
the “groin” (inguen). The name is usually applied to a narrow but indetermi- 
BUTTOCK 
BUTTOCK 
vju .VIA 
Fig. s.—The female perineum and surrounding parts. (After His.) 
nate area of the abdomen immediately above this shallow furrow, and the adjacent 
area of the thigh just below it. 
Below the pubes are some of the generative organs—those which are super- 
ficially located, the external genitals {genitalia externa). In the male is the organ 
of copulation, whose technical title, penis, has practically displaced the entire NAMES AND DELIMITATIONS OF SURFACE PARTS. 
OCCIPUT 
lit CERVIX.I 
NECK COULUM I 
SHOULDER 
OMOS 
ELBOW 
LOIN 
LUMBUS 
ANCON 
BUTTOCK 
NAT IS 
HAM 
POPLES , 
CALF 
SURA, I 
GASTROCNEMIA I 
OUTER ANKLE^ 
/MALLEOLUS EXTERNUS 
Fig. 6.—Back view of a man. On one lateral half the names of the parts are given in English, on the other 
in Latin. (P. H. G.) 28 
INTROB UCTOB Y. 
group of Anglo-Saxon names by which it was formerly known. The free end 
of the penis, the “ head,” or glans penis (literally “ the gland of the penis,” from 
its resemblance to some internally located secreting glands), is covered by a long, 
movable fold of integument, the “ foreskin,” or “ prepuce ” (preputium). At 
the tip of the glans is a little slit, meatus urinarius, the termination of the com- 
mon passage-way of the urine and semen. Behind the penis hangs the “ bag ” 
(scrotum) in which are suspended the essential male organs of generation, the 
two “ balls ” or “ stones.” which are more usually called by their Latin name 
testes (witnesses) or by the Anglicized diminutive of this word, “ testicles.” In 
the female the group of external genitals is designated by the name vulva, for 
which modern English dictionaries, with a fastidiousness not always imitated in 
popular speech, afford no single-word synonym. These structures are sometimes 
called pudenda, which means “ things to be ashamed of”—as if such a criticism 
could justly be applied to the organs which are necessary for the perpetuation of 
the human race. The vulva presents a fore-and-aft cleft, which starts just below 
the pubes and runs backward between the thighs. This fissure is bounded later- 
ally by thick folds of skin, labia majora (the greater lips), upon separation of 
which are seen the clitoris (which is the suppressed representative of the penis), 
two thin folds of membrane, labia minora (the smaller lips), the meatus urinarius, 
and the opening of the vagina, the tube which leads to the “womb” (uterus). 
Behind the external genitals of both sexes, between the thighs, and in front of 
the lower opening of the bowels is a narrow antero-posterior area called perineum, 
a word with no vernacular equivalent (Figs. 4 and 5), The rear limit of the 
perineum is marked by the outer opening of the anus, the terminal portion of 
the alimentary canal. 
The posterior surface of the trunk (Fig. 6), generally called the “back” 
(dorsum), shows in the middle line from end to end a furrow in which appears 
a continuous series of bony prominences, each of which belongs to a separate 
segment of the pile of bones called the spinal column, or, naming the whole from 
a part, merely the spine or back-bone. Between the lower margin of the thoracic 
cage and the crest of the hip on each side, in the region known as the small of 
the back, is a “loin” (limbus). 
Projecting from the trunk are the “ limbs ” or “ extremities ” (membra or 
extremitates,) arranged in two pairs, an upper and a lower. Each pair has a 
bilateral symmetry, and therefore the statements which apply to one limb need 
not be repeated for its mate of the opposite side. 
The “ upper limb ” or “ upper extremity ” (membrum superius or extremitas 
superior) is divided naturally into four distinct segments. These, in regular order 
from above downward, are shoulder, arm, forearm, and hand. The “shoulder” 
(omos) connects the trunk and arm. The “ arm ” (brachium) extends between the 
shoulder- and elbow-joints. Beneath the shoulder-joint, and between the side of 
the chest and the arm, is a pyramidal space, with its base presenting downward, 
called the “arm-pit” (axilla). The “forearm” is known as o.ntebrackium, which 
is the exact Latin equivalent of the English name, and also as cubitus, from which 
comes the name of a measure of length anciently employed. It includes all 
between the elbow- and wrist-joints. Its upper end is marked behind by a prom- 
inence, the “ elbow” (ancon). The fourth and final segment of the upper limb is 
the “hand” (manus). This is subdivided into a proximal portion, the “wrist” 
(carpus), a central part, which constitutes the body of the hand, the metacarpus 
(meaning “beyond the carpus”), and a distal part, the digits” (digiti). The 
front surface of the metacarpus is the “palm” (palma), and the hind surface is 
the “ back ” (dorsum manus). There are five digits to each hand, numerically 
named, beginning with that farthest from the median line of the body and 
counting inward. They have also other designations, which are used with equal 
or greater frequency. The first digit (digitus primus) is the “thumb” (pollex); 
the second (digitus secundus) is the “ fore finger” (digitus index); the third (digitus 
tertius) is the “ middle finger ” (digitus medius) ; the fourth (digitus quartus) is THE SYSTEMS OF ORGANS AND THEIR FUNCTIONS. 
the “ ring finger ” (digitus annularis, from annus, “ a ring ”); and the fifth 
(digitus quintus) is the “ little finger ” (digitus minimus, literally “ the least finger ”). 
Each digit has three segments, except the thumb, which has but two. 
The lower limb is the homologue of the upper—that is, it is built on substan- 
tially the same structural plan.1 It has four segments : hip, thigh, leg, and foot, 
which correspond respectively to shoulder, arm, forearm, and hand. Between 
hip and thigh is the hip-joint; between thigh and leg, the knee-joint; and 
between leg and foot, the ankle-joint. The “ hip,” or haunch (coxa), is so firmly 
united to the back-bone that it serves as a portion of the wall of the abdomen, 
the greater cavity of the trunk. Behind the hip and immediately below the loin 
is a large mass of muscle and fat, the “ buttock ” (natis). The “ thigh ” extends 
from the hip to the leg, and is technically called femur, which name is also applied 
to the single bone that forms its framework. The prominence in front at its 
lower end is the “ knee ” (genu), and the space opposite the knee on the posterior 
aspect is the “ham” (poples). The mistake of calling the buttocks the hams 
is often made, but has no justification. From knee-joint to ankle-joint is the 
“leg” (crus). Its rear bulge is the “calf” (sura or gastrocnemia, literally “the 
belly of the leg ”), and the sharp vertical ridge in front is the “ shin.” At the 
lower end of the leg are two bony prominences, the “ inner ankle ” (malleolus 
internus) and the “ outer ankle ” (malleolus externus). Malleolus means “ a little 
hammer.” The “foot” (pes), like its homologue the hand, is divided into three 
parts—a hindmost, the tarsus, a middle, the metatarsus, and a foremost or distal, 
the “digits” (digiti). The “instep” of popular nomenclature has no equivalent 
in anatomical terminology, as it includes parts of both tarsus and metatarsus; 
and, on the other hand, there are no vernacular words corresponding to tarsus 
and metatarsus. The part of the tarsus which projects to the rear is the heel 
(calx) ; the top of the foot is its “ back ” (dorsum pedis); and the entire under 
surface is the “sole” (planta). The five digits are designated numerically, like 
their homologues in the hand, the count beginning, however, not at the outer 
end of the series, but at the inner—that nearer the median line of the body. 
Thus, the “ toes ” or digits of the foot (digiti pedis) are first, second, third, fourth, 
and fifth (primus, seeundus, tertius, quartus, and quintus), respectively. But the 
first and last have other names also, the one being commonly called the “ great 
toe ” (pollex pedis, “ the thumb of the foot,” or hallux) ; and the other the “ little 
toe” (digitus minimus pedis, literally “the smallest digit of the foot”). In giving 
the Latin names for the toes it is rarely necessary to employ pedis (“ of the 
foot ”) to distinguish those of the lower extremity, as the context indicates which 
limb is concerned; and it is never essential to say manus (“ of the hand ”), as 
this is understood unless the contrary is obvious. 
In studying anatomy the thoughtful learner is almost certain to conclude that 
he needs to know a great deal about every other part in order to comprehend 
fully the one which he has in hand. No organ, however simple, is independent: 
every one is so related to others, perhaps to many others, that they are absolutely 
essential to its life. In the same way it is true that some knowledge of many 
is necessary to the complete, or even sufficient, understanding of a single one. 
This fact constitutes a chief obstacle in the path of the anatomical student; but 
it may be diminished very considerably, and its residue rendered less discour- 
aging, by his having presented to his mind at the beginning of his course a con- 
THE SYSTEMS OF ORGANS AND THEIR FUNCTIONS. 
1 The difference between homology and analogy must be borne in mind. Homology relates to 
similarity of structure, analogy to likeness of function. The two do not always go together, tor 
example, the upper limb of a man and that of a bird are homologous, because they are constructed 
on the same plan ; but they are not analogous, because the one is used for prehension (grasping), and 
the other for locomotion (flying). The organization in the two cases is strikingly similar ; the func- 
tion is radically different. But compare the wing of a bird with that of a butterfly; both are devoted 
to the same use—namely, flying; but they are essentially different in structural plan, as can be seen 
on the most cursory inspection. Therefore they are analogous, but not homologous. 30 
INTB OD UCTOB Y 
cise recital of the principal organs of the body and a statement of the chief 
function of each. In this way he will learn a number of most useful anatomical 
facts, and they will be grasped all the more readily because they are strung on 
a physiological thread. In the few succeeding pages an effort is made to afford 
the student just this assistance. 
Organs Removing Waste Matters. 
The human body is a machine, and, like every other machine, wears out in 
using. We all know that even in circumstances favorable for the preservation 
of a corpse, such as coolness and dryness of the atmosphere, it undergoes destruc- 
tive changes so rapidly that before many days have passed what was once an 
object of beauty and the occasion of delighted admiration becomes altogether 
grewsome and revolting. And yet, swift as is this putrefaction, the wearing out 
of the tissues in life is more speedy. The greater the physical activity of a man, 
the more rapidly are his textures broken down. Every movement, however 
trifling, every glance of the eye, every thrill of sensation, every thought or 
emotion, is attended with destruction of substance. The products of this waste 
are poisonous, and if retained in the system in any considerable amount cause 
sickness and even death. But there are channels by which these effete and toxic 
materials are continually escaping—namely, the lungs, the skin, the kidneys, and 
the bowels. Water, the common vehicle in the body-changes, carries them out 
in solution. The solvent and vehicular services of water are very manifest in 
the case of the urine, which is loaded with the waste escaping through the 
kidneys; and they are often as plain in the case of the perspiration, which 
contains the effete matters discharged through the skin. The excrement which 
comes from the bowels is not in solution when it appears, but this is due to its 
loss of water subsequently to its formation and during its detention in the intes- 
tine. Other products of decomposition are borne out with every expired breath, 
this being saturated with water, as appears by its visible condensation whenever 
the surrounding air is sufficiently cooled. 
The Vascular System. 
At this point there naturally arises the question of the means by which the 
various effete materials that are constantly being formed in every part of the body 
get to the four outlets named. This carriage is accomplished by the vascular 
system, which consists, first, of a complicated series of tubes, the blood-vessels, 
connected with which is a powerful organ, the heart, which drives the blood in 
a continuous current through them ; and, second, of another set of tubes, the 
lymph-vessels, whose stream of lymph flows into that of the blood. Almost 
everywhere in the body there are minute crevices between the elementary 
particles and threads of the tissues, and into these chinks the textures discharge 
their wasted molecules, always in solution in water. These tissue-crannies com- 
municate witli little cylindrical tubes, into which the liquefied waste is poured. 
The tubes are lymph-vessels, and they conduct theiv contents to certain blood- 
vessels, where it mingles with the current of blood. Some effete matters pass 
from the tissues directly into the blood. The blood is contained in and com- 
pletely fills the heart and the blood-vessels associated with it, these being, first, 
the arteries, which are tubes through which the blood flows from the heart to the 
tissues ; second, capillaries, microscopic tubes of wonderful thinness and delicacy, 
through which the blood flows in the midst of the tissues; and, third, veins, 
through which the blood flows away from the tissues. The heart, which is 
a kind of force-pump, drives the blood through this great system of tubes in 
a ceaseless stream, and thus brings it in practical contact with the tissue-elements 
that make up the various organs. When the blood, laden with impure matters 
from every part of the body, comes to one of the organs (kidneys, lungs, bowels, ORGANS SUPPLYING NOURISHMENT. 
31 
or skin) which is capable of withdrawing decomposition-products from it, the 
particular poison which this organ can abstract is removed, and the blood is by 
just so much rendered less impure. Coming to another one of them, it gets rid 
of the foul material which can be unloaded at this door of exit; and so on at 
the others. The lungs are sewers for certain excrementitious substances, the 
kidneys for others, the skin for a third group, and the intestines for the remainder. 
In this way are eliminated all of the materials which result from the constant 
wearing out of the body. 
If there were no compensation for the destructive changes which are going 
on incessantly, in a very short time every life would cease. But just in propor- 
tion to the extent of the waste, and practically simultaneously with it, repair 
takes place. As an old particle lapses from a tissue a new one supplies its place 
without delay, even as the ranks of an army, though constantly suffering from 
the ravages of disease, death, and desertion, are kept full by the enrolment of 
fresh recruits. The portals of the body by which the new materials are intro- 
duced are the respiratory and the alimentary organs. 
First of all in importance is the respiratory system, which embraces the nasal 
passages, the pharynx, the larynx, the windpipe, the bronchi, the bronchial 
tubes, and the lungs, the last being the essential parts. But some critic observes 
immediately that the lungs have been mentioned already as channels of elimina- 
tion. Very true, but they are also channels of appropriation. Not only do 
they expel vile and injurious waste matters with every outgoing breath, but they 
admit to the blood pure and sustaining nutrient material with every incoming 
breath. Here is one of the economies of nature—the wagon is never empty : 
it carries out the offal and it returns with a load of food. Second, we have the 
alimentary tube, with its attendant organs, the salivary glands, the pancreas, and 
the liver. This tube is very long, including the mouth, part of the pharynx, the 
gullet, the stomach, the small and the large intestines, the last mentioned having, 
like the lungs, the double and contrary functions of appropriation and excretion. 
It is furnished with apparatus by which solid food can be chopped, crushed, 
moistened, and reduced to a pulp, and other contrivances which dissolve and 
change the food in various ways until it is in such condition that it can pass 
through the walls of the tube and enter the capillary blood-vessels and lymph- 
vessels, which form fine networks in the substance of its walls. Passing into 
these two sets of vessels by the process of absorption, some of it reaches the 
blood immediately, and the remainder somewhat indirectly by way of the 
lymphatics. The blood, therefore, is seen to be enriched by gaseous material 
in the lungs and by liquids and liquefied solids in the alimentary tube. All of 
these additions are brought by the veins to the heart, and thence are pumped 
into the arteries. The latter pour their contents into the capillaries, which are 
embedded in the tissues. These minute vessels are so thin that the nutrient sub- 
stances in the blood can pass through their delicate wall, come into direct 
contact with the tissues, and flood them with food. To each tissue is offered 
a repast substantially identical with that furnished to every other, but no two 
of them choose the same articles from this sumptuous table, each having a selec- 
tive capacity for those things which are best adapted to the preservation of its 
own peculiar characteristics. So, each tissue having appropriated whatever it 
needs, the residue of the nutrient material is carried away by the lymphatics along 
with the waste products already mentioned. It will be observed that it is the 
vascular system which takes supplies to the tissues, and the same system which 
carries from them the products of waste. 
In connection with the alimentary tube were mentioned, as accessory parts, 
the salivary glands, the pancreas, and the liver. These are true glands—that is, 
organs which abstract certain materials from the blood, manufacture them into 
Organs Supplying Nourishment. 32 
INTJi OB UCTOB Y. 
new substances, and discharge these last into cavities or upon surfaces. The 
salivary glands empty their products into the mouth ; the pancreas and the liver 
pour theirs into the small intestine; and these fluids—saliva, pancreatic juice, 
and bile—effect certain digestive changes in the food. 
Organs of Internal Secretion. 
There are other organs which resemble true glands in their general gross 
appearance, but are unlike them in an important respect: they have no tubes 
through which their products can be discharged upon a surface or into a cavity, 
and hence they are called ductless glands. They are the thyroid, thymus, and 
suprarenal bodies. It is supposed that they furnish substances which produce 
a profound impression upon nutrition, and that these matters, as soon as formed, 
are thrown into the blood, whence the material for their formation was originally 
derived. 
Certain organs are devoted to the work of movement. Through their instru- 
mentality man is enabled to seize and retain his food, to defend himself from 
and to assail his enemies, to move about from place to place, and to do numberless 
other acts in which motion is the principal factor. The organs giving man such 
power are muscles. They form the most of the bulk of the limbs and a great 
part of the walls of the cavities of the trunk. The lean meat of animals, which 
is a part of our food, is muscular tissue. 
Organs of Motion. 
Framework Organs. 
All of the organs of the body are held in suitably close relation to each 
other, and are yet kept from crowding together with injurious force, by certain 
structures which are called skeletal. The most striking and familiar of these are 
the bones, which form a stable framework for the various parts, a strong protec- 
tive wall for cavities containing organs of great delicacy, and powerful levers 
upon which the muscles act. Cartilages are usually closely associated with bones, 
but there are cases in which cartilages by themselves perform just such services 
as bones more commonly do. However conspicuous these hard structures may 
be in their peculiar line, of work, it is doubtful if they are of more use in 
the animal economy, even in their peculiar province, than are certain soft, 
flexible tissues. The fibrous tissues do almost all of the minute detail of sup- 
port, the bones and cartilages being devoted only to the coarser kinds. All 
through the organs is a fine network of these tissues, furnishing a veritable 
skeleton for the microscopic elements of which the organs essentially consist. 
There are also substances which serve as stuffing and cushion-material for 
various parts. 
Organs of Relation. 
Of all the organs, those constituting the nervous system are the most exquisite 
in structure and the highest in function. They are the brain, the spinal cord., 
numerous small collections of nervous tissue called ganglia, and a great 
number of cords, the nerves, each of which has a connection at one end with 
some one of the nervous masses above mentioned. The nervous system gets 
its proper share of attention from the other organs which have been 
spoken of as engaged in carrying off waste, furnishing material for repair, 
moving parts or the whole of the body, and doing the passive service of 
framework. But it acts as if it recognized the great obligation resting on 
nobility, and it returns the devotion of its humbler neighbors by services of 
the most exalted order. It regulates and harmonizes the operations of all of the 
other parts, keeping them up to their work, restraining them if a tendency 
to overdoing appears, sustaining the equilibrium of all the functions. But, in METHODS OF STUDY. 
33 
addition to all this, it brings the individual into conscious relation with the world 
around him through the medium of the organs of special sense. Without this 
last service our lives would be purely vegetative. 
Organs of Reproduction. 
The functions of the organs thus far mentioned concern only the individual, 
providing, first, for his preservation, and, second, for his relation to the things 
around him. There are other organs—not, however, in a condition of functional 
activity during the whole of life—which are necessary to the preservation of the 
race. These are the organs of generation. One series of them is present in the 
female, and its chief members are the ovaries, which furnish eggs; the Fallopian 
tubes, by which the eggs are conducted to the womb (uterus); the womb itself, 
in which the eggs, if fertilized, may remain during the period of pregnancy; the 
vagina, which receives the penis of the male in copulation and gives passage to 
the young when the time for its birth has arrived; and the mammce, from which 
the progeny obtain sustenance for a considerable period. The other set of organs 
belongs to the male, and its principal parts are the testicles, which furnish the 
essential part of the semen for the impregnation of the eggs; certain tubes by 
which the semen flows to the urethra, the conduit common to the urine and the 
generative fluid ; and, finally, the penis, the member by which sexual connection 
is effected and the male product deposited in the female generative passages. 
THE ORDER OF TOPICS. 
The chapters in this book are arranged substantially in the conventional order. 
First comes a brief presentation of the elementary tissues, followed immediately 
by a chapter on embryology. Then succeeds the descriptive anatomy, in which 
the organs are treated in systems, and after this the topographical, which deals 
with the relations of the different organs to each other. 
That the account of the histologic materials composing the various organs 
should precede the description of these structures, and that the mutual relations 
of the latter should not be presented until the organs themselves have been 
described, are so logically necessary as to require no explanation. But the suc- 
cession of topics in the systematic anatomy should be made to vary according to 
circumstances. 
If the learner is studying anatomy only, the arrangement set forth in the 
table of contents is useful. But if he is studying physiology at the same time, 
he would do well so to modify the order that he may obtain a knowledge of the 
structure of each organ just before its function is considered. As physiology is 
concerned largely with the contents of the cavities of the body, this plan will 
involve the study of the viscera, including the brain and cord, early in the course. 
Any hours which are fairly due to anatomy and are not consumed in this prepa- 
ration for the profitable study of functions should be devoted to osteology, and 
after this has been mastered the topics would best be taken up in the order as 
stated—joints, muscles, fasciae, vessels, and nerves. 
METHODS OF STUDY. 
Any work which is done according to a prearranged system is more econom- 
ical of time and effort and more productive of desirable results than that which 
is done in an unmethodical way. It is particularly important for the student of 
anatomy to follow lines wisely laid down for his guidance, because of the limited 
time at his disposal in which to acquire a mastery of the multitude of facts need- 
ful for his subsequent progress. Some words of counsel, therefore, are here 
offered as to the methods of study which experience has shown to be 
advantageous. 34 
INTRO I) UCTOR Y. 
Merely reading the text-book is productive of but little good. Many a man 
who has done this faithfully is utterly unable to answer a question which 
would be likely to be included in the list prepared by any competent board of 
examiners. The facts are so numerous, and often so seemingly unrelated to each 
other, the names of objects are so unlike anything previously known, and the 
allusions are so frequent to matters which must remain unexplained until a later 
part of the course, that it is wellnigh impossible to bring away from a single 
reading, however careful, much more than a chaotic impression of the subjects 
considered. Some students in their desperation resort to the plan of verbal 
memorizing—learning word for word the descriptions in the book. It is hard 
to conceive of a method more wasteful of energy and less fruitful of results. 
One who has done this may be able to pass a brilliant oral or written examination, 
but he has not begun to be an anatomist; he is helpless in the presence of the 
dissected subject, and incapable of using what he has studied in any practical 
way. A student should not allow himself to adopt this method. He must learn 
the facts in such a way that a permanent image of every object is produced in 
his mind, and thus his knowledge will be available at the bedside. Of course 
it is necessary to acquire a nomenclature—to learn the names of the objects dealt 
with—for without these labels of things it is impracticable to receive information, 
to retain it easily, or to impart it after it has been gained. But this is a vastly 
different thing from committing to memory the precise phraseology in which any 
author, however learned and eloquent, has framed his presentation of the facts. 
The clearer and more forcible a statement in the book, the better is it for the 
student; but, the idea having been grasped, its clothing of words should be 
ignored. The student should be satisfied with nothing less than such a compre- 
hension of the fact that he can lucidly convey it in his own language to one who 
never heard of it before. 
It is generally very advantageous for the student to have before him the 
object while he is reading the description of it, for thus he is able to verify or 
correct the account which is given, and to get more concrete and enduring ideas 
of the various qualities of the thing itself. When osteology is under considera- 
tion, it is not difficult to pursue this ideal course ; for even if the student cannot 
afford to buy a complete articulated skeleton, he can obtain by a small expendi- 
ture a sufficient number of separate bones to supply almost all of his needs. The 
little outlay required for this purpose will be more than justified by the returns, 
however impecunious he may be. 
Many of the organs cannot be preserved in such condition that they can be 
studied to advantage in any such way as can the bones; but as substitutes for 
them we have casts and models—the former representing exactly the external 
form, size, and color of the originals, the latter in many cases doing this and also 
showing some details of internal structure. Both casts and models may be more 
instructive to the beginner than the objects for which they stand, even supposing 
the latter to be entirely normal, inasmuch as the real specimens are generally so 
soft and flabby that they do not retain their shape as do their artificial represen- 
tatives, which are made of rigid materials and possess the additional merit of 
comparative indestructibility and can be used year after year without appreciable 
diminution of value. When minute parts are in question models are far prefer- 
able to the real objects, as they are of collosal size. The pigmy organ tells its 
story in a tiny voice which we cannot understand unaided; the giant model 
shouts its message in tones which a whole roomful of people can hear. 
But even casts and models are usually not available except in medical schools, 
and we are consequently driven to employ pictures, which, fortunately, are to be 
had in such abundance and of so admirable quality that we often hardly miss the 
the really ideal means of illustration. Every one learns more quickly from a 
good pictorial representation than from the best description, for the mind stores 
up the impressions of form and color which enter it by the channel of sight far 
more eagerly and tenaciously than it does those which reach it by way of spoken METHODS OF STUDY. 
35 
words. Where the subject is very complex, a diagram is commonly more useful 
than the best pictorial representation, because it eliminates everything but the 
essence of the matter, and thus does not confuse the mind by too vast an array 
of facts. The student, however, should scrupulously avoid allowing himself to 
be content with a merely diagrammatic knowledge of any part of anatomy: he 
should use the schematic picture only as a prelude to the actual thing, as the 
map which informs him where and how to find and learn about the unknown 
land and its contents. 
Although descriptions, diagrams, pictures, models, and casts have their dis- 
tinct value, each in its peculiar field, it must never be forgotten that after learn- 
ing all which they can teach it is of the greatest importance to have contact with 
the natural object. Dissection of the dead body supplements and rounds out the 
knowledge which has been previously gained, and its service is indispensable. It 
is not well to attempt dissection until one has learned by other means the prin- 
cipal facts about the part to be dissected, because without such antecedent 
knowledge material, which in most places is scarce and costly, will be wasted by 
unintelligent cutting. But after the student has qualified himself to appreciate 
the views which can be obtained only in the anatomical laboratory, he should 
embrace every opportunity to dissect, for thus only can lie become a practical 
anatomist. When a human body cannot be procured for this work, the manual 
dexterity which is so important an accomplishment for a surgeon may be culti- 
vated by the dissection of cats, dogs, and other animals, which are abundant and 
cheap ; and this practice is a most desirable preparation for the study of human 
anatomy for other reasons than the mere skill in fhe use of some instruments 
which it bestows. 
Among the aids to the acquisition of anatomical knowledge, two which are 
but little appreciated deserve especial mention. 
The first of these is the recitation. In this exercise the student is obliged to 
describe the things which he has been studying. This is a severe but most 
wholesome test of his knowledge. By it his attention is attracted as in no other 
way to the defects of his attainments. Some matters which he had flattered 
himself were perfectly understood are found to have been only partially learned, 
and in others he discovers that he has acquired mistaken notions. The ability 
to describe a thing clearly and fully to others is a convincing evidence of attain- 
ment, and the exercise of it is a capital method of fastening the truth in the 
mind. If possible, the student should associate with himself another of the 
same class, and no day should be allowed to pass without a serious, exacting quiz, 
the two alternating in the office of questioner. 
Valuable as are the quiz and recitation in correcting and increasing one s 
knowledge, they are almost equalled in these respects by drawing. Sight and 
touch give an excellent idea of the form of a bone, but the information gained 
by these means is greatly intensified by making a free-hand picture of it; and 
in the process one is almost sure to see features which were not previously appre- 
ciated, and to rectify some faulty opinions. The same is true of all other objects, 
and the student is earnestly advised to make a drawing of every one of his dis- 
sections. If the natural objects are not available, he should draw the casts and 
models which he has the privilege of studying, and, in default of better repre- 
sentations, even the pictures in his text-book. 
But the objection is at once raised that only a few peculiarly gifted persons 
are capable of drawing. It is not uncommon to hear men declare that they can- 
not learn to draw. This statement, however, is absurdly incorrect, for every 
such objector can already write, and writing is nothing but the drawing of certain 
arbitrary characters. One who makes a capital A can surely outline a tent; n 
he can make an S, he can draw a wriggling snake; in forming an X he has 
pictured a St. Andrew’s cross ; and thus every one who signs his name demon- 
strates .his ability to draw. The talent is undoubtedly more marked in some 
persons than in others, but is possessed in some degree by all; and, however, 36 
INTR OD UCTOB Y. 
slight it may be originally, it can be cultivated to such an extent as to be wonder- 
fully serviceable to the medical student. 
Although the few succeeding paragraphs #re not specifically anatomical in 
their bearings, they have a pertinency in this place because every medical student 
at the beginning of his career should be given the advice which they carry and 
which he is unlikely to find elsewhere. 
Among the articles of equipment which a medical student needs none is more 
important than a good medical dictionary. It is an indispensable. If he ignores 
its aid, he is doomed to stumble and blunder in every direction; if lie accepts 
the assistance which it will give for the asking, he can progress readily and 
vigorously in all the paths of medical study. 
A medical dictionary, in order to be thoroughly serviceable, ought to possess 
the following characteristics: The inclusion of substantially all of the words 
employed by the English-writing medical authors of the time; the arrangement 
of these words in alphabetical order; the various accredited spellings of the 
words; the pronunciation of those words on whose orthoepy one might go astray ; 
the etymon or original form of each, and the simplest translation of it; and a 
concise definition of the word in each signification in which it is employed. 
Several lexicons constructed on these lines are available, any one of which will 
do good service; but one which is less ample will not satisfy the reasonable 
requirements of the student. 
Although the so-called Roman pronunciation of Latin is generally taught in 
the schools and colleges of this country, the dictionaries, for sufficient reasons, 
use the English pronunciation of the Latin and Latinized words which form the 
principal part of the vocabulary of medicine; and this method is recommended 
to the student for his adoption. 
The student is earnestly advised to establish the habit of consulting his dic- 
tionary whenever he encounters a word whose meaning he does not know. He 
should fix the spelling in mind, learn the definition, observe and remember the 
derivation, and repeat the proper pronunciation until the tongue has fully mas- 
tered it. Finally, he will do well to ascertain the kinship of the word, if any 
exists, to other words already known, and to group these all together in his 
memory as relatives. By this method he will rapidly acquire a large vocabulary, 
the ability to employ words with strict regard to their meaning, to spell correctly, 
to pronounce elegantly, and, as an accompaniment and result of this training, he 
will be content with nothing less than precision of thought. ELEMENTARY TISSUES, 
AND THE STRUCTURE OF MEMBRANES AND GLANDS. 
F. H. GERRISH. 
A FULL presentation of microscopic anatomy would require a large volume. 
It is the main purpose of this chapter merely to give a brief description of 
the elementary tissues which enter into the formation of the body. Without a 
knowledge of these primary textures much that must be said of the gross anatomy 
of different parts will be unintelligible ; indeed, it is impossible to understand any 
organ, either from the anatomical or physiological point of view, unless the mate- 
rials of which it is composed and the various physical properties of these sub- 
stances are known with perfect familiarity; for the tissues are to the organs as 
the letters of the alphabet are to written words. 
The minute structure of the viscera will be described in connection with the 
macroscopic features of each organ in turn. 
CELLS. 
The word “ tissue ” means, in ordinary parlance, a web-like structure or a 
woven fabric. Anatomically, it is applied to any organized substance in the 
body. Notice that in this definition the word “organized” is used, not “organic.” 
The latter would, indeed, exclude the substances which are inorganic—that is, all 
of the ultimate elements, of which there are many in the body—leaving them to 
the consideration of the chemist; but it would include quite a number of sub- 
stances found in the body which, although organic, have no title to be called 
structures, and belong in the domain of the physiologist, who deals with the 
proximate principles. Thus, albumin and fibrin are organic substances, but not 
organized; and, consequently, they are not tissues, for tissues are always organ- 
ized. 
Every tissue originally consists of microscopic particles, named “cells,” 
which have been aptly called the simplest expression of tissue. Etymologically, 
the word “ cell ” is an unfortunate designation, based upon a mistaken belief as 
to the structure of the corpuscle. At first it was thought that cells were cysts, 
sacs, vesicles, with fluid contents. But it was long ago learned that they are 
usually solid bodies, and hence a word which implies the existence of a cavity, 
as does “ cell ” (Latin, cella, “ a small, hollow cavity ”), is a misnomer in the 
majority of cases. However, the substitutes proposed have not met with general 
favor, and “ cell ” has become so firmly fixed in our nomenclature that we shall 
not attempt to displace it; indeed, there is no call to do so, since no confusion 
need arise from its use in this arbitrary sense. 
Not only is it true that all of the tissues primarily are composed of cells, but, 
going back much farther than this, we recognize the origin of the entire body 
from a single cell, the ovum (egg). This enforces the saying, which has become 
almost an axiom, that every cell comes from a pre-existing cell. 
37 38 
ELEMENTARY TISSUES. 
Of the numerous definitions of cells, that which seems most exact is the ulti- 
mate morphological elements of the tissues. It is not sufficient to say that they are 
the “ ultimate elements ” of the tissues, because that term refers to their chemical 
constituents : it is necessary that the definition should include a word which 
explains that the elements referred to have a definite, distinguishable, and charac- 
teristic shape, and this requirement is fulfilled by the word “ morphological,” 
the adjective from “ morphology,” the science of form. Thus is conveyed the 
idea that in histological analysis—which is to the microscopic structures what 
dissection is to the macroscopic—we do not go beyond the cell; that this is the 
last thing reached by the process; and that in all of 
the textures it has such definiteness of form as to en- 
able us to differentiate one tissue from another. 
The typical cell (Fig. 7), capable of development 
and reproduction, is a round or ovoid mass of proto- 
plasm in which is a nucleus. 
Protoplasm (from Greek words meaning “ the first” 
and “ the thing formed”) is a substance whose proper- 
ties underlie the vital functions, and therefore it has 
been called the physical basis of life. It is homoge- 
neous, soft, and jelly-like, and possesses contractility— 
the power of shortening a diameter, of drawing one of 
its parts nearer to another. It usually looks granular, 
Fig. 7.—Diagram of a cell. (F. 
H. G.) 
but this appearance will be explained a little later. 
The nucleus is a roundish mass, generally central in location, and named from 
the Latin word which means “ the kernel,” because its situation is so suggestive 
of the meat of a nut. Sometimes the nucleus contains a small body (perhaps 
more than one) bearing to it a relation similar to that which the nucleus itself 
sustains to the cell; and this is called the nucleolus (“ the little kernel ”). 
The typical cell has no investing membrane. The granular appearance of its 
protoplasm is due to a network (spongioplasm) which becomes visible with lenses 
of high power. In the meshes of this plexus is a nearly fluid, homogeneous 
material (hyaloplasm). The nucleus has a similar construction, but has addition- 
ally a limiting membrane. The nucleoli are connected with the reticulum (net- 
work) of the nucleus. One point on the nucleus is called its pole, and the exactly 
opposite point is its antipole. 
The protoplasm may become condensed at the surface, and this hardened 
peripheral part is called the cell-wall. A deposit of chemical substances in 
the wall frequently occurs, and contributes to its solidity. Cells may produce 
material superficially in large amounts without essential change of their own 
shape ; and thus are formed substances called intercellular (“between the cells”). 
Tissues consist of cells and intercellular substance. In shape cells differ widely : 
the various forms will be described in connection with the discussion of the 
respective textures. Some cells are less 
than 0 inch in diameter, others more 
than--go',oo', and between these extremes are 
all possible gradations. 
As has been said, the protoplasm of the 
cell possesses contractility, and this property 
enables it to display movements which are 
known as amoeboid, because they are ob- 
served in a typical form in a unicellular, 
aquatic creature called amoeba. In its 
amoeboid movements (Fig. 8) the cell alters its form rapidly, assuming inde- 
scribably fantastic outlines, due to the irregular contraction, first, of one portion 
of the mass, and then of another part. By virtue of this quality the cell can 
move from place to place, one point becoming fastened, and the rest of the cell 
moving up to it and pushing out a process to a farther point in the same 
Fig. B.—Amoeboid movements. (Haekel.) CELL REPRODUCTION. 
39 
direction. Thus is accounted for the migration of cells from blood-vessels, and 
their wandering from one point to another outside of the vessels. 
CELL REPRODUCTION. 
The formation of new cells is accomplished by division of old cells. The 
direct method, by which every element of a cell was equally divided by a trans- 
verse constriction, was formerly supposed to obtain generally, but is now known 
to be very rare. The indirect plan of division is almost, if not quite, universal. 
By this method the nucleus undergoes a series of complicated modifications, 
which, taken as a whole, are called karyokinesis, a name derived from the Greek 
words for “nut” and “change,” the signification of the compound being “the 
changes in the kernel ”or nucleus. In studying the details it is well to bear in 
mind that in this process, which is the principal movement toward the creation 
of two cells out of one, there occurs such a division of the cell-protoplasm and 
of the nucleus that each of the new-born cells inherits a half of every portion of 
the parent-cell’s estate. 
When division is about to take place the nucleus noticeably enlarges (Fig. 9). 
The nuclear membrane and the nucleoli disappear, and the secondary filaments 
of the reticulum are drawn into the primary threads, making them thicker and 
more conspicuous (Fig, 10). It is not positively determined whether these threads 
Fig. 9.—Nucleus enlarged. The 
body of the cell is represented 
merely in outline in this series of 
diagrams. (F. H. G.) 
Fig. 10.—Nucleoli and second- 
ary filaments have disappeared. 
(F. H. G.) 
Fig. 11.—The spindle and V 
loops, side view. (F. H. G.) 
all unite and make one, or are separate ; whichever is true, they form a peculiar 
and complicated tangle which is called the skein. The diagram does not attempt 
to display all of the tortuosities of the skein, as they are rather confusing. There 
now appears a skeleton spindle (Fig. 11), formed of delicate filaments of the inter- 
stitial substance, placed with one extremity at the pole and the other at the anti- 
pole. At each end of the spindle fibrils of the protoplasmic network converge 
and produce the appearance of rays. At the next step (Fig. 12) a number of 
V-shaped loops are observed in place of the skein, these resulting either from the 
breaking of the single thread, on the one theory, or, on the other, from the plainer 
manifestation of the always separate threads. These V-shaped pieces are short 
and thick, and marshal themselves around the equator of the spindle, with apices 
to the centre and limbs outward, producing a star-like appearance, which is 
Fig. 12.—V loops, end view. (F. H. G.) 
Fig. 13.—Daughter loops, end view. (F. H. G.) 40 
ELEMENTARY TISSUES. 
sometimes called the wreath. Simultaneously with this movement the loops are 
split lengthwise (Fig. 13), so that each original (or mother) loop is made into a 
pair of secondary (or daughter) loops—a most important part of the series of 
changes. Next, the twin sisters in each V-shaped loop turn away from each 
other, one moving her head toward the pole, the other toward the antipole, their 
limbs being interlocked (Fig. 14). Presently they separate entirely, and migrate 
to pole and antipole respectively, travelling along the lines of the spindle, which 
seem to serve as guides to their movements. Arrived at their destination, each 
Fig. 14.—Migration of daughter loops toward pole 
and antipole, side view. (F. H. G.) 
Fig. 15.—Arrival of daughter loops at pole and 
antipole. (F. H. G.) 
forms a star (Fig, 15). Now, as far as can be seen, there has been accomplished 
an equal partition of the original reticulum of the nucleus, and the mass divides 
into two masses which are henceforth distinct nuclei. In each of these two bod- 
ies there takes place a reversal of the steps with which the karyokinesis was 
inaugurated : the V-shaped loops of the stars elongate, their limbs stretch out 
to the opposite side of the nucleus (Fig. 16), and the skein-like appearance is 
observed. Then branches are put forth from the main or primary filaments, and 
Fig. 16.—Division of nucleus into two nuclei, and 
elongation of V loops. (F. H. G.) 
Fig. 17.—Reappearance of secondary filaments and 
nucleoli. Division of entire cell into two. (F. H. G.) 
form the secondary filaments necessary to complete a network. Nucleoli come in 
sight, and a wall is formed around the nucleus (Fig. 17). Before these last stages 
are accomplished the protoplasm of the cell shows a constriction which rapidly 
deepens, and continues to increase until the cell is bitten in two, each part being 
furnished with a perfect nucleus in which is no sign of a spindle. It is held by 
some authors that the wall of the nucleus is not complete, and that thus is per- 
mitted a mingling of the interstitial substance of the nucleus with the cell-proto- 
plasm. However this may be, nobody questions the intercommunication after 
the disappearance of the nuclear wall. 
Various modifications of karyokinesis are frequently observed, but the fore- 
going description comprises the main features in a typical and complete case. THE EPITHELIAL TISSUES. 
41 
CLASSES OP TISSUES. 
I. Tissues furnishing the free surfaces of the body : Epithelial Tissues. 
11. Tissues passively supporting other parts : Sustentacular Tissues. 
111. Tissues performing a nutritive function : Liquid Tissues. 
IV. Tissues devoted to movement: Muscular Tissues. 
V. Tissues essential to sensation : Nervous Tissues. 
THE EPITHELIAL TISSUES. 
Tissues furnishing the Free Surfaces of the Body, 
There is a peculiar propriety in speaking of this class first, as it is composed 
entirely of cells, and also because the male and female cells, by whose union 
every human being is created, are, to all intents and purposes, epithelial cells. 
On every surface which is free, as distinguished from attached, are found 
multitudes of cells, and with hardly an exception the surfaces are covered with 
them or, more properly speaking, completely composed of them. Thus, the top 
layer of the skin is made wholly of cells ; so also is the exposed surface of every 
cavity, tube, or passage which connects directly or indirectly with the skin ; as, 
for example, the alimentary canal from mouth to anus, all of the air-passages, the 
urinary organs, the generative ways; the surface of cavities which are entirely 
closed, which cannot be reached without dissection, such as the pleura, the heart, 
the blood-vessels; and others which need not now be enumerated. 
These cells, thus spread out in close contact with each other, are epithelial 
cells, and the sheet of tissue which they form is an epithelium. Etymology does 
not suggest the character of the tissue, the extent of its distribution, its uses, or 
any other valuable fact about it, the word being derived from the Greek words 
signifying “ upon the nipple.” It is best, therefore, to employ it in a perfectly 
arbitrary way. Many groups of these cells—indeed, all of those which limit the 
surfaces of shut sacs, shut tubes, and other cavities which are not directly or 
indirectly continuous with the skin—are called endothelial, and the sheet of tissue 
which is formed by them is named an endothelium, the derivation giving it the 
meaning of “ within the nipple”—a term which has not even the minute justi- 
fication to be accorded to “ epithelium;” for there is epithelium upon the nipple, 
but there is no endothelium within it, except as there is in every part which con- 
tains blood- and lymph-vessels. As Macalister most pertinently says, “ The dis- 
tinction between endothelium and epithelium is not always either histologically 
certain or functionally possible, nor can its development be relied on as a crite- 
rion.” It would be well if the attempt to keep up the distinction were abandoned; 
but, as some writers still employ the term endothelium, it is well to understand 
that they refer to a cellular tissue which develops from what will presently be 
described as connective tissue. In this book all such will be included under the 
head of epithelium. 
Originally all epithelial cells are nucleated : in most of them the nucleus can 
be demonstrated at any stage of their existence; but in some it becomes oblit- 
erated, usually as the result of pressure or exposure to the drying effects of the air. 
The cells almost literally constitute the entire tissue, the intercellular substance 
being reduced to its lowest terms, and consisting of a minute quantity of a semi- 
fluid, adhesive material called the interstitial cement-substance, which glues the 
cells together. 
Usually an epithelium rests upon a transparent, structureless sheet of extreme 
thinness, rather difficult of demonstration, the membrana propria or basement mem- 
brane. Though called structureless, it is shown to be made up of flattened plates 
of typical connective tissue, which will be treated of a little later. 
An epithelium contains no blood-vessels and a very diminutive supply of 42 
ELEMENTARY TISSUES. 
nerves. When destroyed or in any way lost the cells are regenerated, as a rule,' 
with rapidity. 
Epithelium performs many important services, among which may be men- 
tioned the protection which it furnishes to underlying tissues, the prevention of 
the escape of lymph from the parts which it covers, the absorption of nourishing 
materials into the blood, the maintenance of motion in the fluid which comes in 
contact with it, the smoothness which it imparts to surfaces, the formation of 
secretions, and assistance in the appreciation of certain sensory impressions. 
The materials composing epithelial cells and the substance uniting them are 
sufficiently yielding to permit considerable alterations in their form without 
injury. Thus, when the structures upon which an epithelium rests enlarge or 
contract, it readily adapts itself to the changed conditions, without cracking in the 
one case or wrinkling in the other. 
No classification of epithelial cells is very satisfactory, but the study of them 
is made somewhat easier by the knowledge that (excepting a few—the spheroidal— 
whose form presents but a slight departure from that of the typical cell) they may 
be placed in two classes, in one of which they are long and slender, and are 
arranged with their chief axis perpendicular to the surface, and in the other of 
which they are broad and thin, with the long axis parallel with the surface upon 
which they rest. 
In the first class—the cells standing on end—are columnar (cylindrical), pris- 
moidal, conoidal (pyramidal), pyriform (pear- 
shaped), club-shaped, fusiform (spindle-shaped) 
cells. In the second class—the cells lying on 
side—are flattened (scaly or squamous) cells 
(Fig. 18). 
It will be observed that this classification 
is based upon form only, and that the differ- 
ence between one and another is accounted for 
by the direction in which pressure is applied. 
For example, suppose that a large number of 
soft, globular cells are placed upon an even 
plane, side by side, each just touching every 
immediate neighbor, and imagine that an equal 
number of exactly similar cells are introduced 
additionally upon the same area. Of course something must give way, or the 
proposed problem has no solution ; and what actually yields is the shape of each 
of the plastic cells. The cell cannot go downward, for the surface upon which it 
rests prevents this; sidewise pressure of every adjacent cell deprives it of a con- 
siderable part of its former standing-room ; and, as its bulk remains unaltered, it 
is obliged to move a part of its mass upward, and its free surface, reduced by the 
lateral squeezing, is thrust two or three times as far from its attached surface as 
it was originally. The cell has become elongated, changed from a sphere to a 
cylinder or column, by pressure applied in a number of lateral and parallel direc- 
tions. If the surface upon which the cells originally rested was convex in every 
direction, instead of flat, the cells would be changed from spheres to cones or 
pyramids by pressure made laterally on each at many points, and progressively 
increasing in force from the part nearest the surface downward. The difference 
in results depends upon the variation of the supporting surface. If the cells are 
pressed between two parallel planes, one of which is the surface upon which they 
rest, the result is a flattened cell. It is easy to imagine how the other and less 
common shapes have been evolved. 
Flattened epithelium is often called tessellated, or pavement, because, when 
one looks directly down upon it, it presents the appearance of a flagging of 
stones. The names, however, are objectionable, not only because they are super- 
fluous, but more because they are equally applicable to the columnar variety 
when it is viewed in the same way; for the flat, free ends of the latter look just 
Fig. is.—Flattened epithelial ceils. (Dalton.) THE EPITHELIAL TISSUES. 
43 
as much like a pavement—indeed, are even more suggestive of one than are the 
others (Figs. 19, 20). 
While these classes include nearly all epithelial cells, many cells have pecu- 
liarities which are dis- 
tinguishing, and it is 
convenient to designate 
them by descriptive 
names, such as ciliated 
and priclcle, from their 
appendages; sensory or 
never o-, from their rela- 
tion to the periphery of 
a special-sense organ; 
pigmented, from their 
coloration ; goblet or 
chalice, from their mod- 
ification of shape; tran- 
sitional, from their being: 
Fig. 19.—End view of a number of epi- 
thelial cells, presenting the appearance of 
a pavement. (Ketzius.) 
Fig. 20.—Side view of some 
of the cells of Fig. 19, showing 
that they are long and slen- 
der. (Retzius.) 
y # 
of a rapidly varying form; glandular, from their work in secretion. A brief 
mention of the chief points of each variety is desirable. 
Ciliated cells (Fig. 21) in man are always of the columnar form, and are cha- 
racterized by the projection from their free extremity 
of a number of delicate processes strongly suggestive 
of eyelashes, and hence called cilia. The cilia have a 
constant vibrating motion, with a strong stroke in one 
direction and a weak one in the other. They are sit- 
uated in various parts, but never where they are likely 
to be subjected to hard usage. Thus, they are nowhere 
in the alimentary tract, where the masses of food and 
excrement would injure them ; but they exist almost 
everywhere in the breathing passages, which transmit 
nothing hurtful to them. Their more powerful stroke 
is always made in the same direction ; thus, in the res- 
piratory tract it is invariably such that the mucus which 
smears the surface is moved toward the open end of the 
Fig. 21.—Two conoidal epi- 
thelial cells, their free ends fur- 
nished with cilia. (F. H. G.) 
system—that is, from the deep parts of the lung to the surface of the body. 
Cilia are found in the adult mainly in the organs of breathing and those of 
generation. 
Prickle-cells (Fig. 22) exist in the middle layers of the stratified epithelium 
of the epidermis, the outer layer of the skin. They are poly- 
hedral, and the little spaces between them are bridged over with 
delicate threads, which break when the cells are separated and 
present the appearance of short, rigid spines. 
Sensory epithelium, or neuro-epithelium cells (Figs. 23, 24), are 
found in close relation with the filamentous terminals of the 
nerves devoted to taste, smell, hearing, and sight; from which 
fact the names sensory and neuro- {“ nerve ”) are derived. Such 
a cell is intimately associated at its attached end with the periph- 
ery of a sensitive nerve, and at its free extremity is quite sen- 
Fig. 22.—Prickle- 
cells. (F. H. G.) 
erally prolonged into a stiff, hair-like process, which may project beyond the plane 
of the surrounding surface. These distal bristles receive a shock from a wave of 
the fluid into which they protrude, and this causes a thrill to pass through the cell 
and to agitate the nerve-filament, which carries the impression to the nerve-centre. 
Pigmented cells are found in various situations. They are of different shapes, 
generally very irregular, and have been invaded by (perhaps filled with) black 
particles. In the colored races the lower layers of the epithelium of the skin 
are highly charged with them. 44 
ELEMENTARY TISSUES. 
Goblet or chalice cells (Fig. 25) are a modification of the cylindrical or 
conoidal, and their names are explanatory of their form. The nucleus retreats 
to the attached end of the cell, and the rest of the cell becomes filled with a 
granular material. The granules swell, causing the part in 
which they are contained to bulge out at the sides and crowd 
over into the territory of the adjacent cells; and, finally, the 
internal pressure becomes so great that the cell bursts at its 
free end, its contents escaping upon the surface as a glairy 
substance called mucus. A goblet-cell, therefore, is a one- 
celled gland, doing real secreting 
work. In the true mucous glands 
the secreting cells are of this vari- 
ety. A goblet-cell may soon return 
Fig. 23—Neuro-epithelial 
cells. Three cells project be- 
yond the general surface, and 
are supported by interme- 
diate cells. (Frey.) 
Fig. 24. —Neuro- epithelial 
cells. Two send long processes 
beyond the general surface. 
(Schultze.) 
Fig. 25.—Goblet-cell, surrounded by cyl- 
indrical cells. (F. H. G.) 
to the condition of an ordinary cylindrical or conoidal cell or remain a chalice 
for a long time. 
Transitional epithelium (Fig. 26) partakes of the features of a number of other 
groups. Its typical illustration occurs in the bladder, where the superficial layer 
is composed of thick, flattened cells, with dimples on their under surface into 
which the large ends of pear-shaped cells of the next layer are received, the 
spaces between the last being filled with the inverted cones of the lowest set. 
Fig. 26.—Transitional epithelium. 
(F. H. G.) 
No two layers are alike, and 
a lower is in a state of transi- 
tion to a higher plane. 
Glandular epithelium (Fig. 
27) is composed of cells of dif- 
fering shapes—cuboidal, cyl- 
indrical, conoidal, polyhedral, 
and spheroidal, the last being 
rarely found except in the re- 
motest recesses of tubular and 
Fig. 27.—Glandular epithelium as seen in a salivary gland. At 
the lower right-hand corner is a duct lined with conoidal epithelial 
cells. (Kolliker.) 
racemose glands. The various forms of these cells are accounted for by the dif- 
ferent shapes of the cavities to which each series is compelled to adapt itself. 
The function of glandular cells is secretion. 
When an epithelium consists of only one stratum of cells it is called simple or 
single-layered; when it has two or more layers it is known as stratified. If a 
ciliated epithelium is stratified, only the cells of the upper layer are furnished 
with cilia. THE SUS TENT A CULAR TISSUES. 
45 
THE SUSTENTACULAR TISSUES. 
Tissues Passively Suppoeting Othee Paets. 
1. Mostly fibrous. 
(а) White Fibrous Tissue (Connective Tissue Proper). 
(б) Yellow Fibrous Tissue (Elastic Tissue). 
(c) Areolar Tissue. 
(d) Adipose Tissue. 
(e) Gelatinous Tissue. 
(/) Adenoid Reticular Tissue. 
(g) Neuroglia. 
2. Cartilaginous. 
(a) True Cartilage. 
(b) White Fibro-cartilage. 
(c) Yellow Fibro-cartilage. 
3. Osseous. 
4. Dentinal. 
The members of this large group present many violent contrasts in their 
physical qualities : we find the soft and the hard, the transparent and the opaque, 
the flexible and the rigid, the nearly liquid and the almost stonily solid, the 
fibrous and the granular, the moist and the dry, the colorless, the white, the yel- 
low, the pearly, and the pink. And yet, in spite of these antipodal traits, the 
individuals making up this class have certain common characteristics which dis- 
tinguish it from all others. One which strikes the attention most forcibly is 
the absolute passivity of every member of it: not one of them does anything 
actively; they stand still like stocks and stones, and are acted upon by the other 
tissues; they originate no action. But the service which they perform, though 
humble, is of essential importance, and is measurably presented to the mind by 
any one of the various names borne by the group. “ Sustentacular ” suits our 
purpose excellently, suggesting mechanical support, the upholding that requires 
strength and endurance. “ Connective substance ”is good, as referring to a very 
prominent function—the uniting of neighboring parts. “ Connective tissue,” of 
course, inherently carries an equal significance, but the term has been so much 
used to designate a leading member of the group, that it is not always certain to 
convey one’s intent to include all of them. “Skeletal” is highly descriptive to 
one who has divested his mind of the popular notion that nothing but bony 
structures are entitled to be considered a skeleton. Probably the best term of 
all in our language is “ framework,” because everybody knows that a framework 
may be made of any materials which have suitable physical qualities, and under- 
stands that it does the work of supporting mechanically, of connecting near and 
distant parts of the whole, and of keeping these same parts away from each 
other—the last being an office quite as important as the more prominently men- 
tioned connective work. As, however, the term is so little used in a titular way 
by anatomists, another has been selected to distinguish the group. 
The word u framework,” like “ skeletal,” to an anatomist suggests far more 
than the massive, bony staging, which is the gross basis of the human form. To 
him it means the delicate, and even microscopic, rafters, beams, and shelves, which 
serve to give definite shape to minute organs and to small parts of large structures, 
and to keep their active portions from pressing upon and being pressed upon by 
each other. So, too, in his mind, “ connective ” has both macroscopic and micro- 
scopic applications. It is a name given to the tissue of which are made the 
bands which tie the bones together, and the strong, flexible sinews which unite 
contractile organs to the parts which they move ; and it is equally deserved by 
minute parts which, on a small scale, do work of a comparable kind. 46 
ELEMENTARY TISSUES. 
These tissues are very widely distributed in the body—so extensively, indeed, 
that their diffusion may almost be declared to be universal. If every particle of 
material except the sustentacular tissues were to be withdrawn from the body of 
a person with whom we were well acquainted, there would be no difficulty in 
recognizing him, even in minute details of form. 
It is interesting to observe not only that the sustentacular tissues are similar 
in a functional way, but that they are structurally allied. They originate in the 
same elements of the embryo, to a certain extent they are interchangeable, and 
they often shade into each other. 
They consist of cells and intercellular substance, though in most of them, 
when mature, the cellular elements are inconspicuous, and the material between 
the cells is so largely developed as to constitute almost the entire bulk of the 
tissue. 
White Fibrous Tissue. 
The name of this tissue is highly descriptive, for it is distinctly white when 
seen in a mass, and its fibrous character is manifest. It is often called “ con- 
nective tissue proper,” or even merely “ connective tissue,” because of its great 
abundance, both absolute and comparative, and its very wide distribution; but, 
while its conspicuousness among the sustentacular tissues entitles it to the name 
which implies the fact, the designation is confusing, and would better be dropped 
in favor of the descriptive appellation which is here chosen. Teased out with 
needles and viewed with the microscope, it is seen to consist almost wholly of 
extremely fine, colorless fibrils, arranged side by side in bundles which have an 
undulating outline (Fig. 28). The fibrils may be very long—some inches—and 
do not branch. Closely applied to the bundles of fibrils are cells ; but these are 
not a prominent feature 
in the adult tissue, and 
are liable to escape atten- 
tion unless staining agents 
are used. The cells proper 
to the tissue are flattened, 
irregular, nucleated, gran- 
ular, and have long pro- 
cesses (Fig. 29). 
White fibrous tissue is 
distinguished chiefly for 
its great strength and 
flexibility, and is found 
where these qualities by 
themselves are needed. 
For example, it is almost 
the only tissue in most 
of the bands (ligaments) 
Fig. 28.—White fibrous tissue. 
(F. H. G.) 
Fig. 29.—Cells of white fibrous 
tissue, often called connective-tis- 
sue cells. (F. H. G.) 
which fasten the bones together, and in the cords (tendons) by which the force of 
muscular tissue is transmitted to and applied at distant points. In these situations 
great strength is required, for without it the bones would readily become dislo- 
cated and the muscular contractions would be fruitless of result; flexibility is 
demanded, since rigid ligaments and tendons would either prevent movement or 
break, and thus prove useless. If, in addition to strength and flexibility, elas- 
ticity were added, the bones would get out of place during many movements, and 
muscular contraction, instead of moving the object to which the distal end of 
the tendon was attached, would be devoted in large part to the stretching of 
the tendon itself. 
These illustrations will show that this tissue is well fitted by its physical 
qualities to make up the ropes, cords, protective sheets, and outer shells of 
organs. YELLOW FIBROUS AND AREOLAR TISSUES. 
47 
Yellow Fibrous Tissue 
This texture is composed mainly of fibres, and in large masses presents a 
delicate yellow hue, from which facts it is named. Under the microscope its 
fibres are seen to differ materially from those of white fibrous tissue : they are 
ribbon-like, thick, branched, and curled at the ends into hooks, which result from 
their fracture in the preparatory teasing (Fig. 30). The chief physical properties 
of this tissue are strength, flexibility, and elasticity, the last being that which dis- 
tinguishes it from all others, and gives it the name by 
which it is often known, “ elastic tissue.” Elasticity, 
the quality which restores bodies possessing it to their 
normal shape after distortion, is not to be confounded 
with contractility, the attribute which enables a body 
to shorten a diameter (for example, to draw its two 
ends nearer to each other) under the influence of a 
stimulus. Elasticity is a merely passive property : it 
cannot display itself until some outside force has 
stretched or otherwise deformed the substance in which 
it resides ; but contractility is active, and is manifested 
under influences which have no such effect upon elastic 
bodies. The elasticity of yellow fibrous tissue, while 
disqualifying it for the work of tendons, eminently fits 
it for other duties, and it is found performing valuable 
service in many places. Wherever it is located, it does 
precisely such work as india-rubber would do, if simi- 
larly arranged. It is commonly associated with white 
fibrous tissue, though in relatively small quantities. The 
amount of it in the system is not large as compared with 
that of white fibrous tissue. The clearest masses of it 
are the ligamenta subflava between the laminae of the vertebrae. Its strength is 
not equal to that of the white fibrous. 
Fig. 30.—Yellow fibrous tis- 
sue. (Queckett.) 
Areola is the Latin word for “ a little space,” and areolar tissue gets its name 
from its appearance of being full of minute spaces. It is sometimes called “ cellu- 
lar tissue ”—a term which has no justification to the histologist, to whom the word 
u cell ” has come to have an arbitrary meaning, entirely independent of its etymol- 
ogy. The designation “ cellular tissue ”is applicable properly only to a texture 
made up substantially of the histological elements called cells—such a tissue, for 
instance, as epithelium. 
In areolar tissue we discover no material different from those which we have 
already studied—only a new arrangement of some of them. It is composed of a 
mixture of white and yellow fibrous tissues, so disposed in irregularly criss-crossed 
bundles as to make a network, the meshes of which bound innumerable areolae 
(Fig. 31). The bulk of each bundle is white fibrous tissue, and around it are 
loosely twined threads of yellow fibrous tissue. The little spaces between the 
meshes are not definitely walled, but are indescribably irregular cavities, which 
communicate in the freest way with each other (Fig. 32). The fasciculi are moist- 
ened by a lymph-like fluid, which contributes to their flexibility and diminishes 
the friction between them. 
Areolar tissue is found almost everywhere subjacent to the skin and mucous 
and serous membranes, between muscles, blood-vessels, nerves, and other parts. 
It forms a layer which is attached on one side to the deeper structure, on the 
other side to the more superficial. When one of these structures moves, the 
areolar tissue permits it to slide upon the other for a little distance, the wavy 
bundles of white fibrous tissue being straightened out, and the narrow ribbons of 
yellow fibrous being put on the stretch. The motion ceasing and the disturbing 
Areolar Tissue. 48 
ELEMENTARY TISSUES. 
agency being removed, the strained yellow fibres assert their elasticity, pull the 
white fasciculi back into their undulations, and assist a little in the restoration of 
the parts between which it lies to their 
former attitude of repose. The tissue 
is connective in a typical sense. 
Disease and accident afford strik- 
ing illustrations of the freedom of 
intercommunication of the areolae 
Fig. 31.—Areolar tissue, composed of bundles of white fibrous 
tissue and branched strands of yellow fibrous tissue loosely inter- 
twined. 
Fig. 32.—A portion of areolar tissue in- 
flated and dried, showing areolae. 
and also of the vast extent of this structure just beneath the skin—here called 
the subcutaneous areolar tissue. The lymph-like fluid mentioned above is 
sometimes formed more rapidly than is normal, 
or, what amounts to the same thing in effect, its 
absorption is less rapid than its formation, and the 
excess accumulates in the areolse. But, as each of 
these spaces opens into all of its neighbors, the 
fluid gravitates from one to another into those 
which are most dependent, and these it distends 
proportionately to its amount. In such a case, 
when the feet have been upon the floor all day, by 
evening they are swollen; but, after the patient has 
passed a night in bed in the horizontal position, the 
enlargement disappears almost entirely, because 
the fluid has gravitated back again and has be- 
come widely diffused. Sometimes, as in fracture 
of a rib, a sharp fragment of bone perforates the 
chest-wall and slightly punctures the lung, leaving 
an open tract between some of the air-vesicles of 
the latter organ and the areolar tissue near the 
surface of the body. Every time that air is drawn 
into the lung, some of it escapes through the acci- 
dental opening into the subcutaneous areolar tissue, 
the spaces of which become inflated, at first only 
in the region of the injury, but at each breath 
Fig. 33.—Inflation of subcutaneous 
areolar tissue, due to introduction of 
air through a wound in the chest-wall 
and lung. (Gross.) 
more and more extensively, until finally all of the areolse under the skin are so 
ballooned that the victim presents such an appearance as is shown in Fig. 33. 
The areolar tissue around certain organs, as vessels, becomes somewhat con- 
densed and forms a distinct sheath. The nourishing vessels of a part are situated 
in its areolar tissue. In the narrow spaces between the lobules of a solid organ, 
as the liver; forming a layer outside of the mucous coat of hollow organs, as the ADIPOSE TISSUE. 
49 
stomach; everywhere among bundles of fibres, as in muscle,—in all such situa- 
tions is areolar tissue, furnishing a springy bed for the blood-vessels. Indeed, it 
may be laid down as a rule that vessels are developed in this sort of tissue, and 
always continue to occupy it. 
Adipose Tissue. 
Areolar tissue has been described as composed of white and yellow fibrous 
tissues, disposed in such a way as to leave irregular spaces between their bundles. 
Some of the cells of the white fibrous tissue of this combination in certain cir- 
cumstances undergo peculiar changes. The outer layer hardens, forming a deli- 
cate cell-wall; the most of the substance of the cell is converted into liquid oil; 
and the nucleus, previously central, is crowded olf to one side, thus becoming 
peripheral, and is fastened to the cell-wall. Thus is formed a fat-cell (Fig. 34)— 
a veritable sac of liquid oil, deserving the name 
“ cell” in the etymological as well as in the his- 
tological sense. Such cells are lodged in the 
Fig. 34.—Fat-cells; a, filled with oil; b, exhausted of 
oil, the cell-wall shrivelled. (Kolliker.) 
Fig. 35.—Fat-cells packed closely together 
and thus becoming polyhedral. 
spaces of areolar tissue very generally; but in a few localities they are never 
seen—the penis, the eyelids, the cavity of the cranium, and the lungs (excepting 
a little near the roots). When the number of fat-cells is sufficient to fill the 
areolae even moderately, the tissue is called adipose or fatty. The cells are round 
or ovoid, except when they are closely packed, and then the mutual pressure pro- 
duces angular facets all over them (Fig. 35). Fatty tissue is yellow, soft, and 
resilient when living, but hard when dead. Its quantity is very variable, and 
there is no absolute criterion of the normal quantity. But when its shifting line 
of healthful development is overstepped, obesity or corpulence is reached—a patho- 
logical condition which may interfere with the proper performance of vital functions. 
Sometimes the fat in the abdominal wall attains a thickness of six inches. 
The uses of adipose tissue are various. It is a cushion for organs—the kid- 
neys always lie in a bed of fat, and other organs are similarly provided, though 
less lavishly. Being a slow transmitter of heat, it is a protection against cold— 
it is always found in the great serous apron which hangs down in front of the 
bowels, and doubtless serves to keep them warm. Adipose tissue is a reservoir 
of nutrient material which is drawn upon in starvation. If an animal is deprived 
of suitable food, his system relies largely upon its store of fat in the emergency. 
If a wolf and a sheep are starving, each feeds upon its own fat, the herbivorous 
animal becoming for the time practically a carnivorous one, since it lives on 
fat mutton. A man wasting with fever lives on his own tissues—cannibalistically 
consumes human flesh. The adipose, being a cheap tissue, is used most freely; 
nervous tissue, the most costly, suffers the least loss of weight. During the 
process of starvation the oil is abstracted from the cells, and the walls become 
wrinkled and collapsed. The nucleus, however, keeps alive ; and, when nourish- 
ment is again appropriated by the system, the nucleus becomes active, takes from 
the blood the materials suitable for the manufacture of oil, combines them prop- 
erly, and deposits the product in the cell-cavity, which soon becomes plump again. 
Finally, it is not unworthy to mention the aesthetic effect of a reasonable amount 
of adipose, which softens the asperities of sharp angles, and contributes to the pro- 
duction of the graceful contours, which are so essential to perfect beauty of form. 50 
ELEMENTARY TISSUES. 
Gelatinous Tissue. 
This tissue is jelly-like, as its name implies. It is also called mucous tissue 
and mucoid tissue. No typical example of it occurs in the adult body; but the 
gelatin of Wharton in the umbilical cord illustrates it perfectly. Here is seen 
a protoplasmic network, formed by the union of the processes of cells, which are 
identical with those of white fibrous tissue. In the meshes of this reticulum 
is a semifluid ground substance. This tissue is the most immature form of 
fibrous tissue. 
The vitreous body (or humor) of the eye is composed of gelatinous tissue; but 
the fibrous element is so slightly developed that its existence is by some observers 
denied, and almost all of the cells have disappeared, the few which remain being 
shrunken and indistinct. The vitreous is in large part (about 99 per cent.) water, 
and its appearance is that of a mass of beautifully transparent, colorless, and 
delicate jelly. 
The service performed by the vitreous is strictly sustentacular. It is the 
stuffing which keeps the ball of the eye in its globular shape, preventing the 
wrinkling of the retina, which would be utterly destructive of definiteness of 
sight. When lost, the vitreous is not restored, having a low vitality and prac- 
tically no recuperative power. 
Adenoid Reticular Tissue. 
The word reticulum is the diminutive of the Latin rete, “ a net,” and conse- 
quently means “a little net.” “Adenoid” comes from the Greek word for 
“gland,” and signifies “gland-like.” Adenoid reticular 
tissue, therefore, means the tissue forming the network in 
gland-like structures, particular reference being had to the 
framework of the so-called lymphatic glands, which are 
far better named “ nodes,” since they are not real glands. 
This network has points of resemblance to areolar tis- 
sue—may, indeed, be regarded as a modification of it. 
The reticulum consists of strands of white fibrous tissue, 
with few, if any, yellow fibres intermingled, and these 
delicate trabecula3 (“little beams”), which support the 
proper substance of the node, are nearly or quite covered 
by fibrous-tissue cells in the shape of broad, thin plates 
closely applied and wrapped around them (Fig. 36). 
Though the most characteristic display of this tissue is 
Fig. 36.—Adenoid retic- 
ular tissue. (F. H. G.) 
in the lymphatic nodes, it is widely distributed in the body, and is particularly 
abundant in mucous membranes. 
Neuroglia. 
Literally, the word neuroglia means “nerve-glue,” and is misleading, for it 
is used as the name of a network supporting the nerve-substance of the brain 
Fig. 37.—Neuroglia cells. (F. H. G.) 
and spinal cord. This reticulum is not made of white fibrous tissue, as is that CAB TIL A GINO US TISSUES. 
51 
of adenoid tissue, but is composed of peculiar bodies, called glia-cells, and their 
processes. The cells (Fig. 37) are irregular and stellate, and their branches are 
frayed out at the end in tufts of minute fibrils, which ramify everywhere between 
the nerve-cells and fibres. 
Besides the neuroglia, there are two other means of mechanical support for 
the tissues of the great nervous centres. From the attached portion of the epi- 
thelial cells which line the cavities of the brain and spinal cord delicate fibrils 
run peripherally and end in the pia, the fibrous and vascular covering of these 
masses. Finally, the pia itself sends prolongations inward, which are of manifest 
sustentacular value. 
Cartilaginous Tissues. 
Cartilage, popularly called “ gristle/’ is a dense tissue, but much less hard 
than bone, elastic, and serving important skeletal uses. 
It occurs in three varieties : 
True or Hyaline Cartilage. 
White Fibro-cartilage. 
Yellow Fibro-cartilage. 
Hyaline cartilage is so named from the Greek word for “ glass, because ot 
the transparency of a thin slice of it. It is also called true cartilage, because it 
is the only variety which presents pure and nnmixed the features which charac- 
terize this tissue. It encrusts the parts of bones which enter into the composition 
of movable joints, in such situations, being called articular cartilage; it forms 
the extensions of the ribs to or toward the breast-bone; it constitutes the bulk 
of the larynx ; it stiffens the windpipe and bronchial tubes with strips and 
plates; it is the framework of the front of the nose, and does similar service in 
one or two other places. Hyaline cartilage is opaque, bluish-white, firm, elas- 
tic, and readily and smoothly cut 
with a knife. Covering it closely is 
a coat, called perichondrium (“ around 
the cartilage”), which has an outer 
fibrous and an inner cellular layer, 
and is the agent by which the pro- 
tection and growth of the cartilage 
are effected. Under the microscope 
cartilage is seen to consist of small 
clusters of roundish, nucleated cells 
(Fig, 38), each group crowded into a 
little cavity {lacuna, “ a little lake ”), between which and its neighbors is an 
expanse of apparently homogeneous intercellular substance (matrix). The cells 
are modified fibrous-tissue cells (the so-called 
connective-tissue cells), and the matrix is 
really composed of extremely delicate fibril- 
-I®, the mass of which is pervaded by minute 
lymph-channels. Cartilage is non-vascular, 
and the nourishing material for the parts far- 
thest from the surface permeates the tissue 
through these lymph-paths. 
White fibro-cartilage is otherwise known 
as fibrous cartilage and fibro-cartilage. It 
makes the great disks between the bodies 
of the vertebrae, the plates at the movable 
symphyses, the masses between the bones in 
the freely-movable joints, and the nodules 
which strengthen tendons in exposed situa- 
tions. It has no proper perichondrium, and, indeed, is more like tendon than it 
is like true cartilage. Microscopically (Fig. 39), it is seen to consist of a dense 
A 
B 
c 
Pig. 38.—Cartilage-cells: A, mother cell; B, (7, daugh- 
ter cells. (Testut.) 
Fig. 39.—White fibro-cartilage. 52 
ELEMENTARY TISSUES. 
felting of white fibrous tissue, imbedded in which are nests of cartilage-cells, as 
if the seeds of cartilage and those of connective tissue proper were sown together 
in the same field and developed in an intimate mixture. The physical proper- 
ties of the tissue are such as would be expected from such an association of 
ingredients—elasticity from one element, flexibility and toughness from the 
other. 
Yellow fibro-cartilage is called also elastic cartilage and reticular (“network”) 
cartilage, for structural reasons which will presently be manifest. Its principal 
examples are the framework of the auricle and that of the epiglottis in the larynx. 
It is opaque and yellowish, and more elastic, flexible, and tough than hyaline 
cartilage. Viewed with the microscope, it is seen to consist of a close network 
of yellow fibrous tissue, containing scattered groups of true cartilage-cells (Fig. 
40)—a composition which readily explains its physical qualities. 
As both the second and third varieties of cartilage 
have a fibrous tissue mingled with the true cartilage, 
Fig. 40.—Yellow fibro-cartilage. (Kolliker.) 
the names “ fibro-cartilage ” and “ fibrous cartilage ” 
do not differentiate one from the other. As all carti- 
lage is elastic, the name “elastic cartilage” is not 
clearly helpful in the designation of that containing 
yellow fibrous tissue; and “reticular” is no better as 
a title for the third variety than is “fibrous” for the 
second, since in each its fibrous tissue is arranged as a 
network. The names which are given above are pre- 
ferred because they actually convey a correct idea of 
the structure of each form respectively. 
Osseous Tissue. 
The word “ osseous ” is derived from the Latin os, 
meaning “ a bone.” Osseous tissue, therefore, is bony 
tissue, and it is the characteristic material in the bones. 
A bone is one of the numerous hard organs, which, 
taken together, make up the skeleton. One of the 
long bones of the limbs will show typically all of 
the features which we need for the study of osseous 
histology. 
Fig. 41—Vertical section of a 
long bone. (Testut.) 
A long bone has a central cylindrical portion, the shaft, and an expanded 
portion at each end. The parts of the extremities of the bone which present 
surfaces in movable joints are crusted over with a layer of cartilage, and the rest 
of the bone is covered with a fibrous and vascular membrane, called the perios- 
teum, meaning the structure “ around the bone.” The fibrous part of the perios- 
teum makes it protective; the vascular serves for the nourishment of the bone. 
If the bone is divided into halves by a vertical cut, its shaft is found to be hollow 
(Fig. 41). The open space is called the marrow-cavity, and is lined by a fine, OSSEOUS TISSUE. 
53 
fibrous layer, the endosteum, meaning the structure “ within the bone.” The 
material in the outer parts of the bone is very dense, and is, consequently, 
known as compact osseous tissue. It is very thick in the shaft, but shades 
otf toward the expanded extremities, and in them is merely a thin shell. The 
residue of the bone has the appearance of a network, with the finest meshes 
nearest the outer surface, the coarsest next to the marrow-cavity. It is called 
spongy osseous tissue, on account of its porous character, and cancellous, from 
its being a latticework. But compact and spongy are terms which have ref- 
erence only to gross appearances, which are caused by the arrangement of 
the material: the structure is essentially the same everywhere. The marrow- 
cavity is occupied by the marrow or medulla, a very vascular material, contain- 
ing many peculiar bodies (marrow-cells), which are largely changed into oil as 
adult life is approached, the color of the marrow being, therefore, altered from 
red to yellow. 
Osseous tissue is one of the hardest materials in the body, being surpassed in 
density by two tissues only—dentine and enamel—both of which exist in the 
teeth. It is very tough and elastic, as well as hard, and will resist great strain 
without breaking. It is composed of two kinds of substance, 
earthy and animal, so intimately commingled that, if either is 
removed, the other maintains the form of bone even in its minute 
details. The earthy matter, which is mostly salts of lime and 
makes up two-thirds of the weight of the bone, can be removed 
by the action of a dilute acid. The bone is thus decalcified, and 
consists of a brownish, tough, flexible, and elastic material, so free 
from stitfness that the bone, if a very long one, may be tied into 
a knot (Fig. 42), The animal matter can be driven off by heat. 
hen this has been done, the bone is white, rigid, and brittle to 
the last degree : it can be crushed into fragments between the 
thumb and finger. In the fresh condition the color of bone 
is delicate pink in the compact portion, deep red in the cancel- 
lated. 
If the shaft of a long bone is sawed in two transversely, and a 
very thin slice is removed from the cut surface and examined with 
the microscope, it will be seen that there are numerous nearly cir- 
cular or oval perforations, around each of which is a series of con- 
centric rings, which represent long, hollow cylinders fitted accurately 
one over another, so as to form a solid rod perforated from end to 
end (Fig. 43). This constitutes a Haversian system, named from 
the celebrated anatomist, Havers. The concentric rings are la- 
mellae or laminae (“ layers ”), and the hole in their midst is a 
Haversian canal. In the solid substance of the rod are numerous small exca- 
vations called lacunce (“little lakes”), from which radiate in every direction fine 
channels, called canaliculi (“ little canals ”), which, by uniting with those from 
neighboring lacunae, establish a free communication between the Haversian canal 
and the lacunae farthest away from it. The lacunae and canaliculi are lymph- 
paths, and are important agents in the nutrition of the bone. The Haversian 
canal is occupied by blood-vessels, nerves, and lymphatic vessels, all imbedded in 
a mass of areolar tissue. The canals have a general longitudinal direction, but 
some run more obliquely and connect the more vertical. Immediately subjacent 
to the periosteum and parallel to it is a series of lamellae which form a continuous 
sheath for the more central parts, and are called circumferential lamellae. A similar 
arrangement obtains at the inner free surface, several concentric lamellae encircling 
the medullary cavity, and standing in the relation to it that the Haversian lamellae 
do to their central canal. Indeed, this inner circumferential series with its con- 
tained marrow has been called a mammoth Haversian system. In the spaces 
between the Haversian systems are series of layers arranged at irregular angles 
to each other. They are called intermediate lamellae, and, like the inner and outer 
Fig. 42.—Huinan 
bone which has 
been deprived of 
its earthy matter 
and tied in a knot. 
(Dalton.) 54 
ELEMENTARY TISSUES. 
circumferential, are of periosteal formation, the remnants of an earlier stage of 
growth than is shown in any Haversian system. 
The lacunae are occupied by nucleated corpuscles, called bone-cells, fine pro- 
cesses of which extend into the canaliculi. Lacunae and canaliculi are character- 
istic of osseous tissue, and are found in all true bone. But Haversian canals are not 
present in plates of bone which are so thin that sufficient nourishment is afforded 
by blood-vessels upon their opposite surfaces, as in many lamellae of the cancellous 
tissue, and frequently in a part of the lachrymal bone. 
AREA 
OCCUPIED BY 
I HAVERSIAN 
\ CANAt 
A HAVERSIAN 
SYSTEM 
LAMELLAE 
LACUN/E 
CANALICUL' 
HAVERSIAN 
CANAL 
-COMPLETE 
HAVERSIAN 
SYSTEM 
Fig. 43.—Diagram of the structure of osseous tissue. A small part of a transverse section of the shaft of a 
long hone is shown. At the uppermost part is the periosteum covering the outside of the hone; at the lower- 
most part is the endosteum lining the marrow-cavity. Between these is the compact tissue, consisting largely 
of a series of Haversian systems, each being circular in outline and perforated by a central canal. In the first 
one is shown only the area occupied by a system; in the second is seen the concentric arrangement of the 
lamellee; and in the others, respectively, canaliculi; lacunae; lacunae and canaliculi; the contents of the canal, 
artery, vein, lymphatic, and areolar tissue ; lamellae, lacunae, and canaliculi; and, finally, all of the structures 
composing a complete system. Between the systems are circumferential and Intermediate lamellae, only a few 
of which are represented as lodging lacunae, though it is to be understood that lacunas are in all parts. The 
periosteum is seen to be made up of a fibrous layer and a vascular layer, and to have upon its attached surface 
a stratum of cells. From the fibrous layer project inward the rivet-like fibres of Sharpey. (F. H. G.) 
If a thin layer is peeled off of the surface of a decalcified bone, minute 
projections from its under surface may be seen. These are inward prolongations 
of the periosteum, and are known as the perforating fibres of Sharpey. They 
are not found in Haversian systems, but only in the circumferential and interme- 
diate lamellae, which, as has been already said, are developed from the periosteum. 
They seem to contribute to the strength of the portions of bone in which they OSSEO US TISSUES. 
55 
exist by riveting them together; and they certainly make the attachment of the 
periosteum firmer by giving it a more than superficial hold. Tendons, when 
attached to bone, are prolonged into it as perforating fibres. 
A delicate, longitudinal sliver of bone is seen to have minute openings, which 
Tig. 44. A, transverse section of a long bone, natural size; B, the dark part of A, magnified 20 diameters, 
iiaversian systems of different sizes are seen, with canals, lamellae, and lacunae. The enlargement is not suffi- 
cient to show canalicuh. At 6is a portion of the cancellated tissue. (Peaslee.) 
represent the tracks of canaliculi; and, if the flake is superficial in origin, larger 
holes also appear wherein have lain the perforating fibres. Between the apertures 
is a very fine reticulum of fibrillse, showing the essentially fibrous character of 
the tissue and its consequent homology with 
ordinary connective tissue. 
Marrow fills the cavity of the shaft of the 
bone and extends into the interspaces of the 
cancellous portion. Its elements are supported 
on an areolar network, and it is extremely vas- 
cular, especially in the spongy bone, where, on 
account of the great number and size of the 
vessels, its color is red. In the shaft of an 
adult bone the marrow has been mostly changed 
into adipose tissue, and is yellow. In the mar- 
row are multitudes of cells, like those of fibrous 
tissue, and they are called marrow-cells. There 
are also great, irregular masses, with many nu- 
clei—giant-cells. The marrow and the contents 
of the Haversian canals are practically identi- 
cal ; indeed, they are continuous one with the 
other, and the comparison of the marrow and 
its encircling lamellae with the Haversian canal 
and its surrounding lamellae is not fanciful. 
From what has been said, it will be under- 
stood that osseous tissue consists of cells, fibres, and an interstitial substance, 
which is saturated with lime salts ; and, consequently, that the feature in which 
Fig. 45.—Longitudinal section of compact 
osseous tissue, greatly magnified. The Ha- 
versian canals are cut lengthwise. The dots 
in the canals are the openings of canaliculi. 
(Testut.) 56 
ELEMENT AB Y TISS UES. 
it principally differs from white fibrous tissue is its impregnation with this 
earthy matter. 
It is important to remember that the integrity of the periosteum is essential 
to the proper nourishment of bone, and, if it becomes peeled off by accident or 
by disease, it should be replaced speedily in order to prevent death of the part 
which it supplies with blood. 
Dentinal Tissue. 
Dentinal tissue gets its name from the fact that it makes up the bulk and 
determines the form of the teeth, the Latin for “tooth” being dens. A tooth 
has a crown, the part which projects from the gum ; a fang or root, the part 
buried in the jaw; and a neck, the narrow 
and sometimes constricted part embraced by 
the edge of the gum. If a vertical section 
is made through the middle of a tooth (Fig. 
46) which has a single root, there is brought 
to view a long central cavity, containing the 
CROWN- 
NECK- 
ROOT- 
Fig. 46.—Tooth In vertical section. 
Fig. 47.—Dentinal tubules, in longitudinal section. 
The lower part of the cut shows the portion of dentine 
near the pulp-cavity. (Kolliker.) 
pulp, the latter being composed of vessels and nerves, supported on a staging of 
areolar tissue, and also a great number of cells of the connective-tissue class 
arranged at the periphery of the cavity. Around this pulp-cavity is the hard 
portion of the tooth, in which are three different tis- 
sues : a crust of epithelial tissue all over the crown, the 
enamel; a crust of osseous tissue all over the fang, the 
cementum; and the main mass of the structure, the 
dentine or ivory. 
The dentine is white, very dense, closely allied to bone, 
than which it is a little harder. It is developed from 
closely-packed white fibrous tissue, which becomes infil- 
trated with lime-salts. This compact mass is riddled 
with minute channels, dentinal tubules (Fig. 47), which 
radiate in wavy lines from the pulp-cavity in every direc- 
tion, except at the tip of the fang, where there is an opening through which pass 
Fig. 48,—Dentinal tubules 
in cross-section, showing their 
cavities, walls, and the inter- 
tubular substance. THE LIQUID TISSUES. 
57 
the vessels and nerves. The tubules branch as they pass toward the surface of 
the tooth, and the matrix is particularly dense just around them, thus forming a 
thick wall for each (Fig. 48). The peripheral pulp-cells, called odontoblasts (“ tooth- 
germs”), send delicate processes into the tubules. The undulations of the micro- 
scopic tubules produce an appearance of striation which is visible to the naked eye. 
THE LIQUID TISSUES 
Tissues Performing a Nutritive Function 
An elaborate presentation of the liquid tissues is not needed in an elementary 
work' on anatomy, for a knowledge of them, except in a superficial way, is not 
required for the comprehension of the description of macroscopic structures. 
Consequently, they are treated here in a cursory manner, and the student is 
referred to his text-book on physiology for more detailed accounts of them. 
The liquid tissues are— 
The Lymph. 
The Blood. 
They originate in connective tissue, but are so different from it in appearance, 
physical properties, and function as to merit consideration in a group by themselves. 
Fine and closely stowed as are the elements of the tissues, there are between 
them spaces, mere chinks and crannies, extremely diminutive and indescribably 
irregular, into which ooze from the blood of neighboring vessels nutrient mate- 
rials, and from tissues themselves the substances which result from their 
waste. Thus, the tissues are constantly bathed in a mixture of their food and 
excrement. The spaces containing this fluid communicate freely with each other, 
and open into the beginnings of minute and delicate tubes, which last, uniting 
with others of similar size, form larger tubes ; these pursue a like course, and so 
on until tubes of considerable capacity are reached. The little crevices and the 
tubes are respectively lymph-spaces and lymph-vessels, and their contents are called 
lymph. The word “ lymph ” etymologically means “ water,” but histologically 
and physiologically it is much more than this. It varies in composition in dif- 
ferent parts, being poorest at the periphery and richest near the centre. Exam- 
ined microscopically, it is seen to consist of a clear, fluid portion, liquor lymphce 
(“ the liquid of the lymph ”), and a cellular portion, the latter floating in the 
former, so that this is a tissue whose intercellular substance is liquid. The cells 
are lymph-corpuscles, and are spheroidal, granular, jelly-like, colorless bodies, aver- 
aging y-Yo inch in diameter each, with a vaguely defined nucleus, and capable of 
amoeboid movements. They are sometimes called leucocytes (“white cells”), 
because of the whitish appearance of a mass of them. 
The lymph-vessels which absorb lymph from the small intestines contain, 
during the intestinal digestion of food, not only ordinary lymph, but also products 
of the digestive process. This mixture is called chyle, and is milky-looking from 
the fact that, like milk, it contains a large proportion of oily material finely 
subdivided—pulverized, we would say, if it were a solid. 
The Lymph. 
Like the lymph, the blood is a tissue composed of cells and a liquid intercel- 
lular substance. The fluid portion is called liquor sanguinis (“the liquid of the 
blood”) or plasma. In it float microscopic particles of various kinds (Fig. 49), 
of which the most conspicuous and easily demonstrated are the colorless and the 
colored corpuscles, the former, though without a tint, often being called white, 
and the latter, though yellowish, red, because, when seen in heaps, they present 
respectively the hues which these names suggest. 
The Blood. 58 
ELEMENT AB Y TIBS UEB. 
The colorless corpuscles are globular, granular, about inch in diameter, 
and possess nuclei which are indistinct during the life of the cell. At rest they 
display amoeboid movements. This description will be seen to coincide with that 
of the lymph-corpuscles; and this will not be surprising to one who has learned 
that the lymph-stream pours incessantly into the current of blood, so that what is 
at one moment a lymph-corpuscle, at the next, having entered the blood-vascular 
system, is a blood-corpuscle. The colorless corpus- 
cles are divisible into a number of varieties, which 
are chiefly differentiated by means of staining tests. 
The colored corpuscles are very abundant, num- 
bering perhaps five hundred to one of the colorless, 
and making about one-half of the volume of the 
blood. They are circular, non-nucleated discs, with 
rounded edges and centrally depressed surfaces, 
smooth, amber, transparent, flexible, elastic, and 
about inch broad. Besides these bodies are 
others, inconspicuous and somewhat difficult of dem- 
onstration, which need not be mentioned here. 
The blood is contained in the chambers and tubes 
of the blood-vascular system, from which it does not 
Fig. 49.—8100d-corpuscles. One 
colorless corpuscle is seen at the 
top; the others are colored. (Dal- 
ton.) 
normally escape, excepting in the spleen, where it courses in wall-less channels, 
and in the case of women during menstruation, when it is discharged through 
ruptures in the vessels. 
THE MUSCULAR TISSUES. 
Tissues Devoted to Movement. 
Contractility is in some degree an attribute of various tissues. The typical 
and original cell manifests its amoeboid movements by virtue of its contractility, 
which it brings to bear now in one direction, presently in another. The cilia on 
the free surface of an epithelium are made to perform their rhythmical lashings 
because of contractility in their cells. But the muscular tissues alone depend 
upon this property for the sole functional quality which distinguishes them. 
Their contractility is displayed on a macroscopic scale, and results in the active 
movements by which locomotion of the body and changes in the relation of its 
different parts are effected. 
We distinguish three kinds of muscle, which differ anatomically, and, for the 
most part, physiologically also. They are— 
1. Plain muscular tissue. 
2. Cross-striped muscular tissue. 
3. Cardiac muscular tissue. 
This tissue is known by a variety of names besides that just given. It is 
called smooth, for the same reason that it is called plain, because of the usual 
appearance of its cells ; non-striated or unstriped, to distinguish it from the second 
kind of muscle, which is characterized by a regular criss-cross of lines on its 
cells; involuntary, from the fact that it is not under the control of the will; 
vegetative and the muscular tissue of organic life, because it aids directly in the 
performance of those offices which are classed as vegetative—in the organic action 
which is beneath consciousness. 
It is found, for the most part, in the walls of the hollow organs, as, for exam- 
ple, the alimentary tube, the urinary bladder and the tubes leading to and from 
it, and the arteries and veins. 
It is made up of cells (Fig. 50) which typically are fusiform ; but their ends 
Plain Muscular Tissue. CROSS-STRIPED MUSCULAR TISSUE. 
59 
are sometimes forked instead of being single-pointed, and sometimes the spindle 
shape is lost by the rounding of the extremities. Often there is observed a faint 
appearance of lines running lengthwise, as if the cell were trying to develop into 
a striped fibre. A transverse cut shows that the cell has flattened sides, evidently 
the result of pressure from forcible contact with its fellows. The cell is always 
nucleated, and generally beyond each end of the nucleus is a little collection of 
grannies. The cell has a delicate structureless sheath. The length of the cells 
varies between and T(r inch, the greater part being very small. In some 
situations, as in the arterioles, the cells are separate; 
but usually they are associated in such a way as to 
make bundles (fasciculi) or layers (strata), being 
united by a small amount of adhesive material. The 
cells are aggregated with much regularity, the bulge 
of one being adjusted to the tapering tips of its near- 
est neighbors (Fig. 51). When distinct bundles are 
Fig. 50. Cells of plain muscular 
tissue. (F. H. G.) 
Fig. 51.—Cells of plain muscular tissue arranged in a sheet, 
(F. H. G.) 
formed, they are usually attached at their extremities to some other structure 
through the agency of a fibrous prolongation. 
Cross-striped Muscular Tissue. 
This variety, also, like the plain, has a number of other names: striped or 
striated, from its microscopic appearance; voluntary, because the most of it is 
under the control of the will; the muscular tissue of animal life, because, while it 
has little direct effect upon the organs of the vegetative functions, it is largely 
concerned in those manifestations which are peculiar to animals. This tissue 
makes up a very considerable part of the bulk of the body, is principally con- 
nected with the bony skeleton, and is that material which, in other mammals, is 
called “ flesh ”or “ lean meat.” It is commonly found in coherent masses, of 
varying but definite shape, each of which, taken in connection with a fibrous 
prolongation at each end, is known as a muscle. 
The histological unit of cross-striped muscular tissue is a muscle-fibre, which 
is the homologue of the cell of the plain muscular tissue. This fibre is like a 
long cylinder, with somewhat flattened sides, and rounded or conical ends. Fis 
completely enveloped in a very delicate sheath, the sarcolemma (“the flesh-husk ). 
When examined under an objective of moderate power, it seems to be marked with 
delicate, longitudinal, parallel, and equidistant lines, and with broad, transverse, 
regularly placed bands or stripes, from which the ordinary names of striated oi 
striped (better, cross-striped) originate (Fig. 52). Between these cross-stripes are 
lighter areas, which, with a stronger objective, seem to be divided by a fine line. 
The cause of these peculiar appearances is not manifest until the tissue is studied 
with a microscope of great power, but then it is found that they are deceptive. 
There are no continuous bands or lines running and the apparent 
breaks in the longitudinal continuity of the cross-lines are an illusion, caused by 
the extreme fineness of the contractile material at regularly alternating intervals. 
The accompanying diagram (Fig. 53) will illustrate this. The fibre is represente 
as composed of a series of threads placed side by side in longitudinal rows, i 
of these threads is a fibril (fibrilla), and is marked by alternating bulges an con 
strictions, regularly placed, and arranged in the following order: a long, wioe, 
fusiform bulge, a constriction, a small, globular bulge, a constriction, and so o 60 
ELEMENT A R Y TISS UES. 
from one end of the fibril to the other. Or, to put it in a different way, a fibril 
looks like a fine thread, upon which are strung large, spindle-shaped beads and 
small, round beads, regularly alternating, and leaving a little of the thread ex- 
posed between each bead and its two neighbors. These fibrils do not touch each 
other, but between them, and also separating them from the sarcolemma, is a thin 
(probably fluid) substance, called sarcoplasm. The fibrils are the contractile por- 
Fig. 52.—Part of a fibre of cross-striped muscular tissue 
showing the alternating bands. 
Fig. 53.—Diagram showing the minute struc- 
ture of cross-striped muscular tissue. (F. H. G.) 
tion of the fibre, and, when they contract, their spindles and beads shorten in the 
line of the long axis of the fibre, and swell out in the lateral direction. This 
causes a displacement of the sarcoplasm, which, consequently, pushes out the 
sarcolemma, and thus produces regularly placed protrusions along the surface of 
the fibre. 
If the diagram is viewed at a distance (as across the room), which will 
obscure some of its details, the 
effect is very like that produced 
by the examination of a fibre of 
muscle with a microscope of mod- 
Fig. 54.—Fragment of a fibre of 
cross-striped muscular tissue, show- 
ing fibrils separated at one end by 
teasing. 
Fig. 55 .—Fragment of a fibre 
of cross-striped muscular tis- 
sue, hardened, showing trans- 
verse cleavage. (Kdlliker.) 
Fig. r6. —Transverse section of 
muscle-fibre, showing nuclei. (Tes- 
tut.) 
erate power—faint, longitudinal lines and broad, transverse stripes, the latter sep- 
arated by light intervals, which are crossed from side to side by a thin, dark streak. 
The spindle portion of the fibril is called a sarcous dement; the round beads 
in a single transverse plane constitute what is known as Krause’s membrane. 
In the teasing of a bit of muscular tissue with needles, it happens that many 
fibres are torn, and the broken ends of the fragments sometimes are frayed out CARDIAC MUSCULAR TISSUE. 
61 
like a coarse brush, the fibrils standing for the bristles (Fig. 54). When the fibre 
has been hardened by certain reagents, it will occasionally show a cross-cleavage, 
by which it is divided into discs (Fig. 55). 
Upon the inner surface of the sarcolemma are scattered a number of oval 
nuclei, the muscle-corpuscles (Fig. 56), so unobtrusive that they generally escape 
observation unless reagents are used in the examination. They are regarded as 
nucleated accumulations of the sarcoplasm. 
In a fibre are many groups of fibrils, each collection being called a muscle- 
column. The fibres are aggregated in bundles (fasciculi), and the bundles are 
assembled in the contractile portion of the muscle. The fibres may be 2 inches 
long and inch thick, or only a tenth part of these measurements. In muscles 
or fasciculi whose length is greater than that of their component fibres the latter 
are joined to each other end to end. Fibres commonly do not branch; but in 
some of the lingual and facial muscles terminal divisions may be observed. 
The fasciculi, as a rule, run from one end to the other of the contractile part 
of a muscle ; but exceptions occur in double-bellied muscles and in others which 
have a tendinous interruption of the muscular continuity. The fasciculi, from 
the closeness with which they are packed, have flattened sides, and are thus more 
or less prismoid. 
As has been said above, each fibre has, as its true and perfect investment, the 
sarcolemma. Between the fibres is a delicate areolar tissue continuous with a 
thicker layer of the same, which sheathes the fasciculi; and this is merely an 
inward prolongation of a still more pronounced 
lamina which coats the entire muscle. The outer 
tunic (I ig. 57) of the muscle is called epimysium 
( upon muscle ”); the sheaths of the bundles 
constitute the perimysium (“ around muscle ”) ; 
and the tissue between the fibres is the endomys- 
ium (“ within muscle ”). All of these are con- 
tinuous, each with the others, and all are composed 
of areolar tissue. 
Fibres which end in tendon come to it either 
in line with its axis or obliquely to it. The sar- 
colemma of the end of the fibre is very closely 
attached to the tendon, and there is a continuity 
of the areolar tissue between the fasciculi of the 
muscle and that between the bundles of the tendon. 
In these ways the two parts of the muscle are so 
firmly united that their separation by violence is 
extremely rare. 
The blood-vessels course between the fibres in 
the areolar tissue, making a network of long meshes. Lymph- 
atics, also, are numerous in the areolar tissue, and the nerves 
of the muscle are abundant. 
Fig. 57.—Sheaths of muscular tis- 
sue in cross-section. The muscular tis- 
sue does not appear, hut is represented 
hy the spaces between the partitions. 
Outside of the entire muscle is epimys- 
ium; between the bundles is perimys- 
ium ; between the fibres is endomysium— 
the last shown in two areas at the right. 
Diagrammatic. (F. H. G.) 
Cardiac Muscular Tissue. 
The muscular tissue of the heart has peculiarities, which 
ally it to the plain muscular tissue on the one hand and to 
the cross-striped on the other. It is like the former in being 
composed of nucleated cells, and in being beyond the control 
of the will; it resembles the latter in being cross-striped, and 
m presenting in a mass a color similar to that of voluntary 
muscle. The cells (Fig. 58) are short, branched at one end, 
cross-striped (though with less regularity and plainness than 
m the case of ordinary striated muscle), and are not fur- 
nished with sarcolemma. The cells are connected with their 
mu^uiar’tissue! °(Testut.) 62 
ELEMENTARY TISSUES. 
neighbors by an abrupt union, and form fasciculi and net- 
works (Fig. 59). The cardiac muscular tissue has a remark- 
ably abundant supply of blood- and lymph-vessels. 
THE NERVOUS TISSUES. 
Tissues Essential to Sensation. 
The nervous apparatus is conveniently considered under 
two heads—the central portion and the peripheral portion. 
The former comprises the brain and spinal cord, and is 
otherwise known as the cerebro-spinal axis; the latter in- 
cludes the cords which radiate from this axis, and also the 
ganglia (“ knots ”) upon these cords. In both the central 
and the peripheral regions two kinds of tissue are recog- 
nized, which are distinguished by their color as gray and 
white. The white is much the more abundant in both 
regions, but there is a great deal more of the gray in the 
central than there is in the peripheral. Functionally 
regarded, the gray matter is that which receives impres- 
sions, retains, converts, and marshals them in various ways, and originates 
impulses : it is the part which feels, thinks, remembers, wills; the white matter 
merely conveys impressions and impulses, connecting the gray matter with distant 
parts and associating one portion of it with another. The gray is cellular; the 
white is made up of fibres. Nerves consist of fibres of this kind, grouped together 
in bundles of small or large size. 
The gray nervous tissue is composed of cells, called nerve-cells or ganglion- 
cells (Fig. 60). These vary greatly in shape and size in different parts, but 
they all have certain common features which are characteristic. They are 
granular, nucleated, usually pigmented, and have projections or processes which 
are called poles. At least one pole of a cell is prolonged as a nerve-fibre (Fig. 
61), and thus it is seen that there is a struc- 
tural connection between the two kinds of 
nerve-tissue. The other processes of the 
cell—of which there may be many—radiate 
from its general mass, divide again and 
Fig. 69.—Cardiac mus- 
cular tissue, the cells uni- 
ted in a network. (Testut.) 
Fig. 60.—Nerve-cells. (Dalton.) 
Fig. 61.—Nerve cell. All of the processes are protoplas- 
mic except that marked a, which is the axis-cylinder pro- 
cess ; b indicates a clump of pigment-granules. (Gerlach.) 
again, and terminate in minute twigs, which mingle with, but do not become 
continuous with, corresponding ramifications from neighboring cells. These pro- 
cesses are called protoplasmic processes or dendrites (“ tree-like ”). A nerve- 
cell, with its dendrites, and the nerve-fibre which is continuous with the cell, 
constitute a neuron. 
The white nervous tissue (called white on account of the appearance of a mass 
of it) is made up of fibres which vary in diameter and length, but have their THE NER VO US TISSUES. 
63 
main difference in the presence or absence of a certain coat. The simplest, 
because least clothed, of the fibres are small, pale, fibrillated, nucleated threads 
of tissue, whose component fibrillse are the minutest independently recognizable 
portions of the tissue. Such a thread is called a pale fibre, and also bears the 
name “ non-medullated,” on 
account of the lack of the 
tunic which distinguishes the 
other kind. It sends otf mi- 
nute filaments at a right angle 
with its course soon after 
emerging from the cell, and 
then continues without fur- 
ther branching until near its 
... 
end, where it divides into 
bundles of fibrillse, each of 
which splits up into smaller 
bundles, and so on, until the 
fibre has frayed out into its 
ultimate filaments. 
NERVE CELL.— 
'^DENDRITES. 
AXIS-CYLINDER. 
NAKED 
AXIS-CYLINDER PROCESS. 
-COLLATERAL BRANCH. 
■MEDULLARY SHEATH. 
Besides the pale fibres is 
a more numerous class, called 
white or medullated fibres. A 
typical representative of this 
variety has three parts, of 
which the first and essential 
is centrally located, and from 
this fact is named the axis- 
cylinder (axis-band or axial 
fibre). The axis-cylinder is 
like a pale fibre, being fibril- 
lated, giving off fine, lateral 
twigs near its origin, and di- 
viding into its ultimate fibril- 
lae at its periphery in the same 
manner. 
AXIS-CYLINDER 
CLOTHED WITH 
MEDULLARY 
SHEATH. 
-AXIS-CYLINDER. 
NEURILEMMA. 
AXIS-CYLINDER 
CLOTHED WITH 
MEDULLARY 
SHEATH AND 
NEURILEMMA. 
Outside of the axis-cyl- 
inder is a thick, insulating 
tunic, composed of a soft, oily 
material (myelin), and known 
as the medullary sheath or 
white substance of Schwann. 
Surrounding this first coat is 
a second, very delicate and 
thin, but sufficiently strong 
to keep the medullary sheath 
in shape. It is called the 
primitive sheath, neurilemma 
(“ nerve-husk”), or nucleated 
sheath. The medullary sheath 
is evenly spread upon the 
axis-cylinder, excepting at 
regular intervals, where it is 
AXIS-CYLINDER I 
CLOTHED WITH 
NEURILEMMA. I 
AXIS-CYLINDER."■ 
NAKED 
TERMINAL BRANCHES. 
lacking for a minute space, thus leaving the primitive sheath as the sole covering 
of the fibre. At these places the fibre presents the appearance of being encircled 
with a cord so tightly as to squeeze the medullary substance away from the part. 
These constrictions are known as the nodes of Ranvier, and the lengths of fibre 
between them are called the internodes (Fig. 62). 
Fig. 62.—A neuron. (Stshr.) 64 
ELEMENT AR Y TISS UES. 
The primitive sheath has on its inner surface a nucleus for each internode, 
midway between the ends of the latter. Either or both of the sheaths may be 
lacking; and in the latter case the axis-cylinder alone is left, and we have a pale 
fibre instead of a white one. In brief, the axis is always present as the one 
essential thing in a nerve-fibre; if it is coated with the medullary sheath, 
it is a white fibre; and it may be in one part naked and in another clothed. 
There is no break in the continuity of the axis from one end to the other. 
The filaments or fibrillse composing it are held together by a cement called 
neuroplasm. 
A number of nerve-fibres gathered into a coherent bundle constitutes a funicu- 
lus (“ little rope ”). It is enclosed in a sheath of laminated fibrous tissue, called 
perineurium (“around nerve”), from the innermost layer of which shelf-like trabec- 
ulae project between irregular groups of nerve-fibres, and compose the endoneurium 
(“ within nerve”). A single funiculus with its wrappings may constitute a nerve; 
but usually a number of funiculi are grouped together in a nerve, and, when this 
obtains, they are kept in close relation to each other by a common sheath, the 
epineurium (“upon nerve”). The bundles in a nerve have a network arrangement, 
each funiculus splitting up more or less at short intervals, and its component fibres 
passing into neighboring funiculi (Fig. 63). 
The fibres, however, always retain their in- 
dividuality : while they cross and recross 
in the nerve, and any one of them may be 
an ingredient of many funiculi in passing 
Fig. 63.—Connection between the bundles in a 
nerve. (Dalton.) 
Fig. 64.—Branching of a nerve. (Dalton.) 
from centre to periphery, there is never any coalescence between them. In the 
branching of nerves the same rule is observed : a funiculus lets some of its fibres 
switch off at the side or separates them into substantially equal parts, but the 
fibres themselves remain undivided (Fig. 64). The larger vessels of a nerve 
course in its sheath, and the capillaries are arranged in long meshes between the 
fibres. The epineurium is also supplied with nerves, called nervi nervorum (“the 
nerves of the nerves ”). 
The origin of nerves varies with their function. Those which convey impulses 
from the centre to the periphery, called efferent nerves (meaning “ carrying from”), 
grow outward from nerve-cells in the centre; while those which convey impres- 
sions from the periphery to the centre, called afferent (meaning “carrying to”) or 
sensory nerves, grow inward from nerve-cells in organs of special sense or in MEMBRANES. 
65 
ganglia. These fibres branch within the nerve-centre, and send their ultimate 
twigs among the cells, but do not unite with them. 
Ganglia (“ knots ”) are bunches of various sizes occurring in the course of 
nerves. They are made up of nerve-cells and their coverings, massed upon and 
between the fibres of nerves (Fig. 65). Each 
cell of a ganglion has one or more axis-cyl- 
inder processes, which are prolonged into 
nerve-fibres. The ganglion is clothed with 
areolar tissue, which sends trabeculse through 
it in every direction. 
Before coming to their peripheral divis- 
ion many medullated nerves lose their white 
substance ; but others retain it during several 
stages of branching, and in these last the 
division takes place at nodes. After the 
disappearance of the medullary sheath the 
primitive sheath continues for a variable 
distance. 
Afferent (sensory) nerves have various 
peripheral terminations. Some of them end 
Fig. 65.—Arrangement of nerve-cells and 
nerve-fibres in a ganglion. (Dalton.) 
in cells, others in special organs, as tactile corpuscles, end-bulbs, and Pacinian 
bodies. These will be described in the chapter devoted to the organs of the 
senses. Certain afferent nerves end peripherally by the final separation of the 
axis-cylinder into its component fibrils, which run between the tissue-elements, 
and generally either end there or else penetrate the cells. The sensory nerve- 
endings in tendons are often suggestive of the ending of motor nerves of volun- 
tary muscle, to be described presently. Close 
to the muscle proper a medullated fibre passes 
into the tendon, divides repeatedly, and the fil- 
aments of the axis-cylinder penetrate widely 
into the tendon. 
Efferent nerves have different endings ac- 
cording to the variety of muscle to which they 
are distributed. In the case of the plain mus- 
cular tissue the fibrillse of the nerve are brought 
close to the muscle-cells, after the nerve has 
formed a plexus in which ganglion-cells often 
occur. In cardiac muscle the nervous filaments 
come from a long-meshed plexus, and are ap- 
plied to the contractile fibres. Finally, in stri- 
ated muscle, after the formation of a close 
plexus, the nerve loses its white sheath, the 
axis-cvlinder enters the muscle-fibre, and just 
beneath the sarcolemma splits up into its fibril- 
he, which spread out in a thin mass of granular 
Fig. 6G.—Motorial end-plate, the termi- 
nation of a nerve in a fibre of cross-striped 
muscle. (Testut.) 
material in which nuclei are embedded. This is the motorial end-plate (Fig. 66) 
MEMBRANES. 
In its widest meaning the word “membrane” is used to designate any thin 
expansion of tissue, either simple or compound. Thus, we speak of the perios- 
teum, the covering of bone, as a fibrous membrane; we call the layer of cells 
beneath the epithelium of free surfaces the basement membrane; and a structure 
composed largely of blood-vessels may be known as a vascular membrane. But 
in a restricted, although the commonest, sense the word is applied to a broad, 
sheet-like organ, with a free (unattached) surface, furnishing the covering of a 66 
ELEMENTARY TISSUES. 
part or the lining of a cavity. With the latter signification the term is employed 
in this section. 
The type upon which all of the members of the group are constructed consists 
of a foundation of white and yellow fibrous tissue, which is limited toward the 
free surface by a single layer of very thin, plate-like cells, and upon this last an 
epithelium (Fig. 67). The fibrous tissues are felted into a layer of variable thick- 
Fig. 67.—A typical membrane in vertical section. (F. H. G.) 
ness, strength, flexibility, and elasticity, according to the proportion and arrange- 
ment of its ingredients, and is called the corium (“ leather”). The lamella of 
flattened cells surmounting this is really a part of the corium, for it consists 
merely of cells of the white fibrous tissue, greatly attenuated and adhering to 
each other at their edges. It is termed the basement membrane. Finally comes 
the epithelium, which presents upon the free surface, and may be either simple or 
stratified in numberless layers. 
In most cases the attached surface of the membrane is connected with the 
underlying structures by areolar tissue, abundant or scanty, which permits some 
gliding of the membrane on the subjacent parts. This areolar tissue is called 
subserous, submucous, subcutaneous, and so on, according to the kind of mem- 
brane under which it lies. The line between it and the corium of the membrane 
is not exactly determinable, as a rule, the two structures being made of precisely 
the same materials, differing only in their mode of arrangement, and gradually 
shading from one into the other. When the membrane is peeled off from the 
areolar tissue its under surface is flocculent, on account of the attachment of 
bundles of the fibrous tissues of the latter. In the areolar tissue course the larger 
vessels and nerves of the region, sending their branches to, or receiving their 
radicles from, the corium. 
There are four classes of membranes: 
1. Serous Membranes. 
2. Synovial Membranes. 
3. Mucous Membranes. 
4. Cutaneous Membrane. 
SEROUS MEMBRANES. 
Of all the membranes, the serous are the simplest—the nearest the type which 
has been described. They are always moist 
with a fluid very like blood-serum, and from 
this fact they derive their name. They are 
thin and transparent, permitting a view of 
the immediately subjacent parts, fairly strong, 
considering their delicacy, and somewhat elas- 
tic. With a single exception, which obtains 
in all females, but never in males, the serous 
membranes are shut sacs ; that is to say, they 
have no opening by which they communicate 
with the surface of the body (Fig. 68). In 
the simplest of them this condition is so plain 
as to be easily understood ; in the most com- 
plicated it is not especially difficult to demon- 
strate, even though the form of the membrane 
Fig. 68.—Diagram showing arrangement of 
a serous membrane. The broken line repre- 
sents the membrane lining the closed cavity. 
(P. H. G.) SEROUS MEMBRANES. 
67 
suggests but remotely that of a sac. In those which are manifestly bag-like, and 
which furnish a complete or partial coating to internal organs, two parts are rec- 
ognized—that which is attached to the viscus, and that which is fastened to the 
walls of the cavity in which the organ is contained. The former is called the 
visceral layer, the latter the parietal (“on the 
wall ”) or reflected portion. The relations of 
parts will be easily comprehended by reference 
to Fig. 69. 
The diagram represents a viscus pushing one 
wall of the serous sac inward, thus making this 
portion serve as a tunic for the organ ; conse- 
quently, this is the visceral part. The other por- 
tion of the sac lines the wall of the cavity in 
which the viscus now is enclosed, and is, therefore, 
the parietal part. It is not asserted that this is 
the precise way in which the viscera procure their 
serous coat; but the condition which exists is such 
as would obtain if this procedure were actual. 
For the sake of clearness in the diagram, a 
cavity is represented between the epithelial sur- 
face of the visceral layer and that of the parietal 
Fig. 69.—Diagram showing that when 
a viscus encroaches upon the space of a 
cavity, it still remains outside of the 
serous membrane, which gives it an 
external tunic while continuing to nne 
the cavity. (F. H. G.) 
layer ; but, as a matter of fact, the two layers are in actual contact, and the serous 
cavity, of which mention is often made, is not real, but virtual. 
Serous membranes present many folds, which connect viscera with each other 
or with the walls of a cavity, or simply project into a cavity and return on them- 
selves, forming a tassel or an apron. A serous membrane may line a fibrous bag, 
and be reflected over the surface of a contained viscus, and in such case is denom- 
inated a fibro-serous membrane. 
The corium is thin, but contains blood-vessels, lymph-vessels, and lymphoid 
and adipose tissues. The lymphatics are especially abundant. The nervous supply 
is small and is sympathetic in origin. 
The epithelium (Fig. 70) is always single and flattened, the cells having irreg- 
ular, notched edges and fitting accurately together, 
except that, at intervals, little apertures are found, 
some of which are the beginnings of lymph-ves- 
sels, and from this fact are named stomata, from 
the Greek word for “ mouthand others are 
filled with processes from cells in the corium, and 
hence are called pseudo-stomata (“ false mouths ”). 
The true stomata are distinguished by a little 
boundary of cells, much smaller than those fur- 
nishing the general surface. The demonstration 
of their immediate connection with lymph-vessels 
led to the belief that serous membranes are only 
expansions of lymphatics, and, consequently, are 
Fig. 70.—Part of free surface of a 
serous membrane, showing the flat- 
tened epithelial cells and the stomata. 
(F. H. G.) 
to be regarded as belonging to the lymphatic system. Their physiological per- 
formance and their behavior in disease support this theory. 
The epithelial surface is particularly smooth and glistening, and thus the 
gliding of opposing portions is accomplished with very slight friction, which is 
still further reduced by the presence of the thin fluid constantly secreted by the 
cells. This fluid, which lubricates the membrane, is normally present in so small 
an amount that it merely moistens the surface. Just as fast as it is formed it is 
withdrawn by the lymphatics through the stomata. But, in disease, when the 
equilibrium between secretion and absorption is so disturbed that the lymphatics 
do not carry the fluid away as rapidly as the cells manufacture it, an accumulation 
occurs, the parietal layer is pushed away from the visceral by the intervening 
liquid, and in this way the virtual cavity is converted into a real one. 68 
ELEMENTARY TISSUES. 
Serous membranes may be divided into tolerably distinct classes, as follows : 
1. Serous membranes proper. 
2. The lining membrane of the vascular system. 
3. The lining membrane of certain cavities in sustentacular tissues. 
4. The lining membrane of the cavity of the cerebro-spinal axis. 
1. Serous Membranes Proper. 
Under this head are included the various membranes which result from the 
division of the original serous membrane lining the thoracico-abdominal cavity 
(Fig. 71). These are derived from the single sac by constriction, the thoracic first 
rPleural Cavity 
Pleural Cavities 
L Septum 
v\Transversum 
\Pericardial f 
\ Car it;/ / 
zPleural Cavities 
_Pleurae 
Pericardial Cavity 
Pericardium 
Abdominal 
Cavity 
Abdominal 
Cavity 
Abdominal 
Cavity 
-Peritoneum 
Tunicx Vaginales Testmn. 
Fig. 71.—Diagram showing formation of several serous sacs from the one original sac. (After Gegenhauer.) 
being separated from the abdominal, and then subdivisions of each of these making 
three distinct sacs of the upper grand division—the two pleurae and the pericar- 
dium—and three of the lower grand division—the peritoneum and the two vaginal 
tunics. They are called serous membranes proper, because they present, to an 
extent which the others do not, the features which have been mentioned as cha- 
racterizing this class of structures. The pleurae are the serous covering of the 
lungs; the pericardium encloses the heart; the peritoneum lines the abdominal 
cavity and clothes its contained viscera; and the vaginal tunics perform a similar 
service for the two chambers of the scrotum and the testicles, to which they give 
lodgement. These serous membranes will be treated of in detail in connection 
with the organs to which they are respectively related. 
2. The Lining Membrane of the Vascular System. 
This is the internal coat of the heart and vessels, known also as the tunica 
intima. It bears a close resemblance to the proper serous membranes in 
structure and appearance. Its power of forming a fluid like that of the great 
serous sacs is not to be doubted, but is not demonstrable, as the fluid must mingle 
with the current of blood or lymph as soon as it is formed. One at all acquainted 
with the circumstances favoring the coagulation of the blood, and the necessity of 
having it flow freely through the microscopic tubes which we call capillaries, 
would feel warranted in the declaration that no other membrane than a serous 
would be practicable as a lining to the blood-vessels and lymphatics. If a 
mucous membrane were employed for the purpose, the small vessels would S YNO VIAL MEMBRA NES. 
69 
speedily become clogged with its thick and slimy secretion ; and the thinnest and 
most delicate cutaneous membrane would obviously be too thick and coarse to 
permit the transudation necessary for the nutrition of the tissues. Only a serous 
membrane with its almost frictionless surface and its watery secretion could pos- 
sibly meet the requirements of the case. 
The details of structure of the tunica intima will be presented in connection 
with the description of the heart, blood-vessels, and lymphatics, respectively. 
3. The Lining Membrane of Certain Cavities in Sustentacular Tissues. 
The most conspicuous illustration of this form of serous membrane is found 
in the internal ear. Around the greater part of the membranous labyrinth, which 
is the essential portion of the organ of hearing, and between it and the bone in 
which it is lodged, is a considerable space, lined with serous membrane and filled 
with a watery fluid, which is called perilymph. Another example is found between 
the back of the eyeball and the bed of fat upon which it reposes. It is called the 
capsule of Tenon, and is a shut sac, with a visceral layer upon the globe of the 
eye and a parietal layer attached to the postjacent adipose tissue. It permits free 
movements of the eye in the orbit with the least possible friction. In character 
and function it closely resembles the proper serous membranes. 
4. The Lining Membrane of the Cavity of the Cerebro-spinal Axis. 
The brain and spinal cord are hollow organs. Their cavities are lined with a 
delicate membrane, serous in character, its epithelium being in embryonic life 
ciliated, and its secretion thin and watery. The membrane is known as the 
endyma (“ garment ”) or ependyma. It will be described in the chapter on the 
Cerebro-spinal Axis. 
SYNOVIAL MEMBRANES. 
By certain authorities the synovial membranes are classed with the serous, and 
there are some good arguments in favor of this association. But, while these mem- 
branes have no communication with the surface, and have the same order of func- 
tion as the serous membranes, there are such differences as to justify a separation 
of the one from the other. The group of synovial membranes with which surgeons 
have most to do are not shut sacs, although each forms a part of the wall of a closed 
cavity; they have a different lining from serous membranes ; their secretion is not 
serous; and they are not associated with the viscera. Therefore, they are here 
treated by themselves. 
The synovial membranes form a part or the whole of the enclosure of certain 
cavities, which are associated with the osseous framework or the muscular system, 
or both; and the service which they render is the 
lubrication of parts which glide upon each other. 
A synovial membrane is composed of fibrous 
tissue, having on its free surface an imperfect 
covering of cells (Fig. 72), and thus affording the 
great exception to the rule that free surfaces are 
completely clothed with cells. These cells are of 
no regular shape, are branched, and are gathered 
into little patches, which are scattered over the 
surface, leaving considerable areas upon which no 
cellular structure appears. The cells are often 
called epithelioid, which means “like epithelium.” 
Their secretion is a glairy fluid, which smears 
the entire free surface of the membrane, and is 
Fig. 72.—Synovial membrane—free 
surface, showing imperfect covering ot 
cells. (F. H. G.) 
called synovia, from its resemblance to the white of egg, 70 
ELEMENTARY TISSUES. 
Synovial membranes are divided into the following groups : 
1. Articular. 
2. Vaginal. 
3. Bursal. 
1. Articular Synovial Membranes. 
These occur in those articulations of the bony skeleton wherein two surfaces 
move upon each other. The bones concerned in such a joint are covered on the 
surfaces, which enter into the composition of 
the articulation, with a crust of cartilage, whose 
free surface is very smooth and hard. The bones 
are held together by strong bands of white 
fibrous tissue—the ligaments—which encapsu- 
late the expanded ends of the bones, forming 
hollow cylinders, which bound the joint. The 
inner surface of a capsular ligament is covered 
with a synovial membrane, which is reflected 
from it a little way upon the margin of each of 
the cartilages. Thus, the synovial membrane 
is a short tube with its edges turned inward. 
The arrangement of the parts will be seen in 
Fig. 73. 
If, as sometimes occurs, a ligament or a 
tendon passes across or through the joint-cav- 
ity, the synovial membrane ensheaths it. Oc- 
casionally the membrane exhibits folds, which 
cross the cavity or hang into it like fringes, 
and perhaps contain some adipose tissue. In 
all cases the synovia secreted by the membrane 
lubricates the cartilages and other structures, 
BONE 
BONE 
Fig. 73.—Diagram of articular synovial 
membrane. The cartilages are represented 
as drawn apart for the sake of clearness. 
The synovial membrane is shown by a 
broken line. (F. H. G.) 
which present a free surface in the joint 
2. Vaginal Synovial Membranes. 
These are so named from vagina, “ a sheath/’ and are also known as synovial 
sheaths. They are found in situations where the tendons of muscles run over 
bones, to which they are bound down by strong, fibrous bands. The bone in these 
cases is grooved, and the fibrous tissue bridges over the gutter, thus making a 
FIBROUS ROOF OF THE CHANNEL 
CAVITY OF SYNOVIAL SHEATH 
CAVITY OF SYNOVIAL SHEATH 
BONY BED OF THE CHANNEL 
Fig. 74.—Diagram of a vaginal 
synovial membrane in cross-section. 
The membrane is shown by the 
broken lines. A space is left be- 
tween the tendon and channel-wall 
for the sake of clearness. (F. H. G.) 
Fig. 75.—Diagram of a vaginal synovial membrane in longitudinal 
section. Compare with Fig. 74. (F. H. G.) 
very strong, fibro-osseous canal, through which a tendon passes to its destination. 
The synovial membrane is arranged in the form of a tubular sheath, one portion 
lining the canal, the other investing the enclosed tendon, as will be seen in Figs. 
74 and 75. MUCOUS MEMBRANES. 
71 
In the movements of the tendon friction is reduced to its lowest terms by the 
lubricating agency of the synovia. 
FRONTAL 
SINUSES" 
3. Bursal Synovial Membranes 
DUCTS OF 
LACHRYMAL GLANDS 
\ethmoidal sinuses 
SPHENOIDAL 
J SINUSES 
Other names for these structures 
are synovial bursae, (“ synovial purses ”), 
bursae mucosae (“ mucous purses ”), and 
vesicular synovial membra,nes. A syno- 
vial bursa is a little bag of fibrous tis- 
sue, lined with synovial membrane, and 
placed between parts which move upon 
each other, as two muscles, two tendons, 
a muscle or tendon and a bone, the skin 
and a bone. The sac is connected with 
surrounding parts by areolar tissue, and 
the opposite sides of its internal surface 
are in contact, and kept moist with sy- 
novia. Some of these membranes are 
developed from spaces of areolar tissue 
by closure of connection with surround- 
ing spaces, and condensation of the con- 
tiguous fasciculi of the tissue. 
UPPER LIDSSf 
LOWER LIDS V 
nMAXILLARY 
/“SINUSES 
-.MIDDLE EARS 
TEAR DUCTS 
NASAL 
PASSAGES 
EUSTACHIAN TUBES 
\ MASTOID 
/cavities 
UPPER LIP 
LOWER LIP 
DUCTS OF . 
SALIVARY V 
GLANDS ' 
AIR VESICLES^ 
\\bronchus 
DUCTS OF LIVER 
STOMACHj 
MUCOUS MEMBRANES. 
The serous and synovial membranes 
line closed sacs ; the mucous membranes 
(membra,nee mucosae) line passages and 
cavities which have a direct communi- 
cation with the outer surface of the body. 
Indeed, from the physiological point of 
view, the parts which are covered by 
them are external, for they are regarded 
as inversions of the integument—por- 
tions of the outer investment tucked in 
and modified, but never lacking conti- 
nuity with it. 
There are two separate sets of mucous 
membranes—the gastro-puhnonary and 
the genito-urinary. Each of these con- 
sists of a continuous membrane, which 
lines two series of organs, and varies in 
many respects according to the organ of 
which it forms a part. The gastro-pul- 
monary mucous membrane (Fig. 76) fur- 
nishes a free surface for the alimentary 
and respiratory systems, and gets its 
name from a principal organ of each— 
the stomach and the lungs. The ali- 
mentary port of it begins at the lips and 
passes through the mouth, the middle 
and lowest parts of the pharynx, the 
gullet, stomach, small and large intes- 
tines, and anal canal, and then comes 
GALL i 
BLADDER^ 
DUCTS OF 
.PANCREAS 
COLON 
APPENDIX 
ANAL 
CANAL 
to the skin-surface. In its course it Fig. 76 Diagram of the gastro-pulmonary mucous 
sends offsets to the ducts of the salivary sllowing the continuity of aU lts P 72 
ELEMENTARY TISSUES. 
glands, of the pancreas, and of the liver, to the gall-bladder, and to the vermiform 
appendix. The respiratory portion begins in the nostrils, and passes through the 
entire pharynx, the larynx, trachea, bronchi, and bronchial tubes, ending in the 
air-vesicles of the lungs. From the nasal cavities it gives prolongations to the 
inner surfaces of the eyelids and the front of the eyeballs, and to the chambers in 
the frontal, ethmoid, sphenoid, and upper-jaw bones; and from the pharynx it runs 
through tubes to the drums of the ears and the cavities of the mastoid portion 
of the temporal bones. The genito-urinary mucous membrane lines the genital and 
urinary tracts, as its name implies. The portion which forms a part of the male 
reproductive organs (Fig. 77) leaves its junction with the skin at the distal open- 
RENAL , 
PAPILLA 
PELVIS 
. RENAL 
'■PAPILL/E 
PELVIS 
BLADDER 
EJACULATORY 
DUCT 
'// i | 
DUCTS 
OF TESTIS 
DUCTS / 
OF TESTIS I 
Fig. 77.—Diagram of male genito-urinary mucous membrane, showing continuity of all its parts. (F. H. G.) 
ing of the penis, and is traced through the urethra to within an inch of its proximal 
end, where it enters the male womb and switches off on each side into the ejacu- 
latory duct, from which it sends one prolongation to the seminal vesicle and a 
second to the vas deferens, and through this last runs to the epididymis and the 
ducts of the testicle. In the female the genital tract (Fig. 78) begins at the 
vulva, goes through the vagina, the uterus, and the two Fallopian tubes, at the 
free extremities of which it is continuous with the serous membrane lining the 
abdominal cavity. In both sexes the urinary mucous membrane lines the urethra, 
bladder, and ureters, ending at the papillae of the kidney. 
The variations in the character of the mucous membrane in different parts are 
very great, and changes are extremely abrupt at several points, while in other 
cases the modifications are effected very gradually. The corium (Fig. 79) is gen- 
erally much thicker than in serous and synovial membranes. It contains a com- 
paratively small proportion of yellow fibrous tissue. When it is largely occupied 
by follicular glands, the ordinary fibrous tissue is to a considerable extent replaced 
by adenoid-reticular, in whose meshes are entangled lymphoid cells, thus consti- MUCOUS MEMBRANES. 
73 
tilting a diffuse lymphatic tissue. Usually the corium is bounded toward the free 
surface by a basement membrane, and deeply by a thin layer of plain muscular 
tissue, which is named muscularis viucosce (“ the muscular [coat] of the mucous 
PELVIS/ 
RENAL 
7PAPILL/E 
FALLOPIAN 
TUBE 
RENAL 
PAPILL/E 
PELVIS 
BLADDER 
URETHRA' 
Fig. 78.—Diagram of female genito-urinary mucous membrane, showing continuity of all its parts. (F. H. G.) 
VULVA 
[membrane] ”). The epithelium is the one element in the membrane which is 
never wanting; but there are only a few cases and very limited areas in which it 
is the sole representative, the covering of the cornea being the most conspicuous. 
CO R1 U M 
Fig. 79.—Diagram of mucous membrane in vertical section. (F. H. G.) 
The epithelium may be single or stratified, of any possible shape, and with or 
without cilia. The membrane derives its name from the glairy fluid, mucus, 
which always covers it. This secretion is protective, and is abundant in propor- 74 
ELEMENTARY TISSUES. 
tion to the amount of irritation to which the membrane is subjected. Where the 
epithelial coat is columnar and single, the mucus is furnished very largely by the 
goblet-cells of the epithelium ; but, as these chalices are a modification of colum- 
nar cells, they are not found where the epithelium is flat; and in such cases all of 
the mucus comes from distinct glands, which devote themselves to this work. 
Mucous membrane is generally connected with subjacent parts by areolar tis- 
sue ; but exceptionally this is not present, and then the membrane is attached 
directly. This occurs only in cases where the passage or cavity which the mem- 
brane lines is not subject to distention, as in the nose, where the corium is fastened 
to the bone. In general, the areolar layer beneath mucous membrane is very 
abundant, and the usefulness of this arrangement appears when we consider that 
the corium has but little elastic tissue in its composition, and in many cases is 
pervaded by glandular structures, which would be injured by the stretching of 
the membrane. As a rule, the cavities and tubes which are lined with mucous 
membrane are liable to great changes of size, owing to their intermittent occupa- 
tion by solids and fluids to such an extent as to distend them. Between the 
periods of distention are times of collapse. If the membrane were elastic, like 
serous membrane, and had no delicate glands embedded in its substance, it could 
be stretched within a large range without harm, and would return to its state of 
relaxation on removal of the distorting force ; and in such circumstances it would 
need but a moderate areolar layer between it and the subjacent parts. As it is, 
the membrane when relaxed becomes more or less folded—thrown into shallow or 
deep wrinkles—and presents a series of ridges, called rugae, which in tubes are 
arranged in line with the longitudinal 
axis of the organ (Fig. 80). When a 
Fig. 80—Diagram showing the folding of the 
mucous membrane in a collapsed tube. (F. H. G.) 
Fig. 81.—Diagram showing the etfacement of the 
folds of mucous membrane and the compression of the 
areolar layer when the tube is distended. Compare with 
Fig. 80. (F. H. G.) 
distending force is applied, as in the passage of a bolus of food through the gullet, 
or after a large dinner has been deposited in the stomach, these folds are effaced, 
the membrane becomes smoothed out, and presents an even surface (Fig. 81). 
This extensive change is rendered possible by the abundance of the submucous 
areolar coat, which is strong and elastic. 
Mucous membrane is very vascular, the vessels for its supply running in the 
submucous areolar tissue, and sending minute branches into the corium above. 
Its nerve-supply varies greatly in different parts—some being extremely sensi- 
tive, others dull of feeling. As would be inferred from the amount of lymphoid 
tissue in the corium, its lymphatics are very abundant. The peculiarities of the 
mucous membrane of each part where it exists will be detailed in the description 
of the organs respectively concerned. 
By this term is indicated the membrane which furnishes the outer covering 
of the body, and is ordinarily called skin. It is a complex structure, and has 
CUTANEOUS MEMBRANE. GLANDS. 
75 
a variety of functions, among which is the distinguishing of impressions' of 
touch. It will, therefore, be more appropriately considered with the organs of 
the senses. 
GLANDS. 
A gland is an organ, which abstracts from the blood certain materials and 
makes of them a new substance, which is then discharged into a cavity or upon a 
surface. In other words, a gland is a secreting organ, its process and its product 
both bearing the name of secretion. Simply constructed membranes, such as the 
serous, doubtless perform some secretory work; but it is always of a low order, 
and the resulting product is only slightly different from the materials of which it 
is composed. It would not be expected that the cells upon a plane surface, whose 
principal function is protective, and which are constantly subjected to hard usage 
on account of their exposed situation, would be able to do secretory work of any 
but the most primitive kind. It would be as reasonable to demand a high grade 
of work from an artisan stationed in the middle of a thoroughfare, where he would 
be jostled by every passer. Such a one needs freedom from interference, and with- 
draws from the bustle of the throng into a secluded retreat, where he has every 
facility for doing the most delicate and elaborate tasks. Nature acts in precisely 
this way in constructing an organ which is to make a secretion : a depression 
appears in a membrane—an inversion of the surface-structure takes place—and 
the cells, which are thus removed from the worries and dangers of the open and 
exposed locality, experience various changes. They become plumper and softer, 
their nuclei enlarge, and they develop a capacity for secretion, which their less 
favorably environed neighbors never emulate. The materials which they abstract 
from the blood are so wrought over that their original character is not sug- 
gested by the nature of the secretion of which they are the ingredients. The 
organ which accomplishes this thing is a true gland; and, as a rule, the more 
completely it is guarded from annoyances and interruptions, the more elaborate 
and valuable is its work. 
The essential thing in a gland, as has already been intimated, is the epithelial 
cell. The forms of secreting cells are as varied as possible, but the tendency is 
to keep near the spherical type. Indeed, spheroidal epithelium is hardly to be 
looked for outside of glands. 
The simplest form of a gland is the follicular, a mere dimple in the surface 
(Fig. 82, A). Enlargement of the embedded tube, without dilatation of its open- 
. Fig. 82—Diagram showing development of glands: A, a mere dimple in the surface; B, enlargement by 
amsion; c, enlargement hy dilatation; D, a combination of B and C\ E, a racemose gland; F, development 
ot method of E; G, a single tube intricately coiled. (F. H. G.) 
ing, makes a saccular or flask-shaped gland (Fig. 82, C). Branching of the lower 
parts changes a simple gland into a compound (Fig. 82, B), and what was pre- 
viously the upper part of the secreting organ now becomes the duct of dis- 
charge, its epithelium losing its true glandular character, and becoming more 
like that upon the general surface. By repetition of these processes the 
gland becomes not only larger, but more complicated fibrous or reticular 
tissue occupies the interstices, and affords mechanical support; muscular 76 
ELEMENTARY TISSUES. 
tissue forms around the ducts; and in many ways elaboration goes on, until 
in some glands not a suggestion of the orig- 
inal type remains to casual observation. And 
yet, the parentage of the most intricately con- 
structed gland can be traced back to the 
little inversion of the surface, which has 
been shown to be a simple follicular gland, 
and the structural principle is identical in 
the two. 
Fig. 83. —Compound tubular gland. The 
upper part is the duct; the lower is the secret- 
ing portion. (Kolliker.) 
Fig. 84.—Compound racemose gland. The resemblance 
to a bunch of fruit is very marked. (Milne-Edwards.) EMBRYOLOGY 
J. P. McMURRICH. 
AT one period of its existence every vertebrate animal is represented by a single 
iY cell, from which the adult individual develops by its repeated division and 
by the functional and histological differentiation of the aggregate of cells so 
formed. The cell, however, which has the power of undergoing this development 
is one which results from the complete fusion of two distinct elements, likewise 
cells, one of which is termed the ovum, and represents the female element of 
reproduction, the other being the spermatozoon, the male element. 
The male cell is formed in the testis, and, if a section of a seminiferous tubule 
be examined, an arrangement will be seen which is represented diagramatically in 
Fig. 85. The cells lining each tubule are arranged in several layers, the outermost 
Spermatogenesis. 
Fig. 85.—Development of spermatozoa. 
layer being formed principally by a number of cells known as spermatogones. 
Each of these from time to time divides, one of the cells so produced persisting 
as a spermatogone, while the other becomes what is termed a primary spermato- 
cyte. This cell later divides into two cells, eacli of which is a secondary sperma- 
tocyte, and these, undergoing a further division, give rise to cells termed spermatids. 
Thus, from each primary spermatocyte, by two divisions, four spermatids are 
developed, and each of these last becomes a spermatozoon. In addition to these 
various cells, others are to be found resting upon the basement membrane of the 
tubule, and extending through the various layers of the developing cells, the 
spermatozoa being grouped upon their inner ends. These are the Sertoli cells, or 
supporting cells, and they do not take any part in the formation of the spermato- 78 
EMBRYOLOGY. 
zoa, but, as their name indicates, serve for the support of the germ-cells, and 
probably assist in their nutrition. 
The spermatozoa are the result of modification of the spermatids. Each of 
these latter is at first a round cell with a rather large nucleus, near which lies the 
centrosome. Gradually this cell elongates, the nucleus takes up a position near 
one extremity, an axial filament develops in the cell-body, the centrosome comes 
to lie behind the nucleus, and, as the final result, there is produced the mature 
spermatozoon, a body measuring in length about inch, and consisting of (a) a 
pyriform head composed of the nucleus of the original spermatid, surrounded by 
an exceedingly thin layer of protoplasm ; (6) of a “ middle piece,” immediately 
behind the head, and representing probably the centrosome of the spermatid; (c) 
of the tail, derived from the cell-body of the spermatid, and composed of an axial 
filament surrounded by a sheath of protoplasm, somewhat variable in form, though 
usually simply cylindrical; and (d) of a terminal filament, which is the end portion 
of the axial filament. 
Oogenesis. 
The ovum, as it exists in the ovary, corresponds to the primary spermatocyte 
of the male, and must undergo certain changes ere it is ready for union with the 
spermatozoon.1 When ready to burst from the Graafian follicle, the human ovum 
(Fig. 86) is a spherical cell about 
Yg-Q inch in diameter, enclosed 
within a membrane, the zona 
radiata, and containing a large 
nucleus, situated somewhat excen- 
trically, while centrally there are 
a number of granules of food- 
yolk, a substance much more 
abundant in the ova of other 
mammals, such as the cat, and 
which forms the greater mass of 
the ovum of birds and reptiles. 
The maturation phenomena (Fig. 
87) by a series of divisions con- 
vert the ovum into a structure 
homologous with a spermatid. 
At the first division (A, B, C) the oocyte, as the ovum at this stage may be termed, 
divides into two cells, one of which is, however, very small and is termed a polar 
globule, while the other is practically as large as the original oocyte. By a second 
division (X>, E) a second polar globule is formed, and the nucleus then passes into 
the resting stage and moves toward the centre of the ovum (F). There are thus 
two maturation divisions, just as there are two divisions of the spermatocytes in 
spermatogenesis ; and the polar globules are to be regarded as abortive ova, which 
take no further part in development, but degenerate. 
After the extrusion of the polar globules the ovum is ready for union with the 
spermatozoon—a process which occurs probably, as a rule, in the upper part of 
the Fallopian tube. A spermatozoon penetrating the zona radiata is received into 
the substance of the ovum, and gradually passes centrally toward the ovum-nu- 
cleus. The tail of the spermatozoon is sooner or later absorbed ; but the head— 
which, it will be remembered, represents the nucleus of the spermatid—and the 
middle piece pass on to come into close apposition, and finally to fuse, with the 
ovum-nucleus, the compound nucleus so produced soon becoming converted into 
a division spindle which inaugurates the segmentation of the ovum. 
CELLS OF 
—CORONA. 
'ZONA RADI ATA. 
GERMINAL- 
VESICLE. 
-NUCLEUS. 
.GERMINAL 
SPOT. 
.FOOD YOLK. 
Fig. 86.—Ovum. (Waldeyer.) 
1 Neither these changes nor the phenomena of fertilization have yet been observed in the human 
ovum. They have been observed, however, repeatedly in the ova of many of the lower animals, both 
vertebrate and invertebrate, and their general similarity in all cases makes the probability that they 
occur also in the human ovum almost a certainty. THE EARLY STAGES OF DEVELOPMENT. 
79 
It would seem from these phenomena that the essential feature of fertilization 
is the union of the nuclei of two cells, the small amount of protoplasm present 
in the head of the spermatozoon seeming to play little part in the process. Since 
both paternal and maternal characteristics may be inherited, it has been supposed 
GERMINAL 
-SPINDLE. 
POLAR GLOBULE 
-SPINDLE. 
POLAR _ 
globule" 
FIRST POLAR 
GLOBULE. 
SECOND POLAR 
GLOBULE. 
-FIRST POLAR GLOBULE. 
SECOND POLAR 
GLOBULE 
-SPINDLE. 
■NUCLEUS. 
Fig. 87. Diagram illustrating the phenomena of maturation. (Testut.) 
that the nuclei must be the material bearers of heredity; and, since the charac- 
teristic substance of a nucleus is the chromatin, this has been regarded by many 
authors as the actual substance concerned in transmitting inherited peculiarities 
from the parent to the offspring. 
The Early Stages of Development. 
By segmentation is meant the conversion of the unicellular ovum into a mass 
of cells, a process which results from a series of divisions. The ovum first divides 
(Fig. 88) into two cells (a), each of these again dividing, so that four cells are 
ZONA > 
PELLUCIDA.y 
POLAR / 
GLOBULES. 
Fig. 88.—Segmentation of the ovum. (After van Beneden.) 
formed (6), and, the divisions continuing (c, d), a solid mass of cells, termed a 
morula, is produced (e), A section through such a mass (Fig. 89, will show 
that it is composed of an outer layer of somewhat flattened cells enclosing a 80 
EMBRYOLOGY. 
number of distinctly granular cells. At first no cavity exists in the centre of the 
morula, but soon the outer cells become in large part forced away from the inner 
ones by the imbibition of a fluid supplied by the walls of the uterus, and what is 
, SEGMENTA- 
TION CAVITY. 
Fig. 89.—Sectional views of ovum, after segmentation. (After van Beneden.) 
termed a segmentation cavity is formed (Fig. 89, B). The morula is thus converted 
into a hollow vesicle, termed the blastodermic vesicle, whose wall is formed by a 
single layer of cells, except at 
one region, where what were the 
inner cells of the morula form a 
lenticular thickening (Fig. 90). 
Later, this thickening flattens 
out, its cells becoming arranged 
in two layers, the innermost of 
which is composed of thin flat- 
tened cells, and forms what is 
termed the endoderm layer, while 
the outer one, consisting of cylin- 
drical cells, is known as the ecto- 
derm. External to these two 
layers, again, is a third one of 
flattened cells, termed the covering 
cells, which is continuous with the 
wall of the vesicle, but which 
eventually disappears so as to 
expose the ectoderm cells upon 
the surface. Still later, the endoderm layer, increasing in size, extends outward 
in all directions, and the vesicle presents a differentiation into three regions. One 
ZONA PELLUCi DA. 
✓ ECTODERM. 
CAVITY OF 
BLASTODERMIC 
VESICLE. 
Fig. 90.—Blastodermic vesicle. (After van Beneden.) 
EMBRYONIC SHIELD. 
EMBRYONIC SHIELD. 
Fig. 91—Blastodermic vesicle, viewed from above. 
(Kolliker.) 
Fig. 92.—Blastodermic vesicle, viewed from the 
side. (Kolliker.) 
portion of its surface is occupied by a clear area composed of ectoderm and endo- 
derm, and termed the embryonic shield (Fig. 91); extending from this to about the THE EARLY STAGES OF DEVELOPMENT. 
81 
equator of the vesicle is the region over which the endoderm layer has extended; 
and, lastly, the lower half of the vesicle is formed only of a single layer of cells, 
as in earlier stages. As development proceeds the embryonic shield increases in 
size and assumes an oval shape, and near one end of it there appears a dark longi- 
tudinal band which is termed the primitive streak (Fig. 92, B), and which is formed 
by the fusion of the ectoderm and endoderm. From this line of fusion cells grow 
out on either side into the space between the ectoderm and endoderm, and consti- 
tute a middle layer, the mesoderm. 
The three layers of cells thus produced constitute what are termed the germ- 
layers. and it is bv the differentiation of the cells com nosing' them that the various 
tissues and organs of the embryo 
are developed, each layer giving 
rise to certain definite structures. 
There has not yet appeared, how- 
ever, any distinct indication of the 
embryo proper. This makes its 
appearance soon after the formation 
of the primitive streak in the form 
of a groove (Fig. 93), extending 
from what may be considered the 
front end of the streak almost to 
the front edge of the embryonic 
shield; the groove is bounded by 
MEDULLARY^ 
/groove. 
r EMBRYONIC 
SHIELD. ' 
PRIMITIVES 
STREAK. 
two ridges, which unite in front, 
but diverge somewhat behind, so 
as to embrace the front end of the 
primitive streak. The groove is 
termed the medullary groove, and 
the ridges are the medullary ridges, 
the whole forming the anlage or 
rudiment of the central nervous 
system. Immediately beneath the 
medullary groove another groove 
likewise appears in the endoderm, 
the convexity of this groove being directed toward the floor of the medullary 
groove; its two lips later unite, the cavity of the canal so formed disappears, and 
a solid rod of peculiar texture, known as the notochord, is produced, lying imme- 
diately beneath the central nervous system (Fig. 94). 
Fig. 93.—Formation of primitive streak and medullary 
groove. (Kolliker.) 
NEURAL 
CANAL. 
ECTO- 
DERM.' 
MESODERMAL 
SOMITE 
WOLFFIAN 
DUCT. 
CCELOM OR 
BODY CAVITY. 
MESO- 
DERM. 
CCELOM OR 
BODY CAVITY. 
SOMATIC 
LAYER. 
ENCO- 
DE R M 
NOTOCHORD 
SPLANCH- 
NIC LAYER. 
AORTA. 
VESSELS. 
VESSELS. 
It has already been stated that the mesoderm forms in the region of the 
primitive streak; it also arises from those portions of the endoderm which are 
immediately adjacent to the notochordal groove on either side, and there is thus 
produced on each side of the middle line of the embryonic shield a sheet of 
mesoderm, which, however, early undergoes differentiation. In the first place, 
Fig. 94.—Transverse section through dorsal region of embryo. 82 
EMBRYOLOGY. 
the sheet does not long remain single, but a split occurs in it, so that it becomes 
separated into two layers (Fig. 94), an outer one adjacent to the ectoderm and 
termed the 'parietal or somatic layer, and an inner one adjacent to the endoderm 
and known as the visceral or splanchnic layer. The cavity which separates these 
two layers is known as the coelom, or body-cavity, and at first is continuous through- 
out the entire extent of the mesoderm. A second differentiation, however, early 
supervenes, consisting of the separation, on each side, of a small portion of the 
coelom from the rest, the somatic and splanchnic layers of mesoderm coming into 
contact and fusing a short distance external to the median line, while, at about the 
same time, a series of transverse constrictions divides this inner, narrower portion 
of the mesoderm into a series of oblong boxes which are termed protovertebree, or, 
better, mesodermal somites (Fig. 95). The formation of these somites begins in 
CEREBRAL VESICLES. 
SINUS 
TERM I N ALIS— 
-HEART. 
-MESODERMAL 
SOMITES. 
AREA PELLUCI DA. 
MEDULLARY TUBE. 
•RHOMBOIDAL 
SINUS, 
AREA OPACA. 
1 
PRIMITIVE LINE. 
what will be the neck region of the embryo, and thence extends forward and 
backward until the entire median portion of the mesoderm, not only in what will 
be the trunk of the future embryo, but also in tire head region, is divided into a 
series of somites. Each of these in the trunk region is connected with the more 
peripheral undivided mesoderm by an intermediate cell-mass, which represents the 
longitudinal fusion of the somatic (parietal) and splanchnic (visceral) layers, and 
each contains a small portion of the originally continuous coelom. 
While these changes have been going on, the endoderm continues its extension, 
and finally its edges fuse at the lower pole of the blastodermic vesicle, which thus, 
throughout its entire extent outside the embryonic shield, becomes two-layered. 
The shield itself has also increased considerably in size, and allows certain regions 
to be distinguished. Along its median line are to be seen (Fig. 95) the anlagen 
of the embryo just described, and this region and the immediately adjacent parts 
may be termed the embryonic area; external to this is a region where the shield 
presents a somewhat transparent appearance, and this is termed the area pellu- 
cida; while the more peripheral portions are opaque and receive the name of the 
area opaca. In this last region extensive changes have been taking place in the 
mesoderm : some of its cells arrange themselves so as to form a network of cords, 
into the substance of which fluid penetrates from the surrounding tissues, the 
cords being thus transformed into canals in which lie numerous cells. These 
Fig. 95.—Development of somites. (Testut.) THE UMBILICAL CORD AND THE PLACENTA. 
83 
canals are blood-vessels ; the fluid which they contain becomes the plasma of the 
blood; the outermost cells of the original cords flatten and produce a thin wall 
for the vessels, while the more central cells group themselves into masses, which 
project here and there into the interior of the vessels from their Avails, and are 
termed the blood-islands. An abundant netAvork of blood-vessels traversing the 
area opaca is thus formed, the intervals of the network being occupied by masses 
of unspecialized cells, which are termed substance-islands, and later give rise to 
embryonic connective tissue. Toward the periphery of the area opaca a circular 
blood-vessel, known as the sinus terminalis, is formed, marking the extreme periph- 
ery of the vascular region ; and, though the area opaca may extend beyond this, 
the blood-vessels do not, and it is thus possible to divide the area opaca into a 
more central area vasculosa and a more peripheral area opaca proper. The forma- 
tion of blood-vessels begins a little later in the area pellucida, and thence they 
groAv in toward the body of the embryo. 
The Umbilical Cord and the Placenta. 
The embryo at this stage is represented by a thickening occupying the median 
portion of the embryonic shield. The anterior end of the thickening now begins 
to sink doAvn into the interior of the vesicle, a process which is continued until 
finally only the posterior extremity of the embryo remains at the surface (Fig. 96, 
fl). The embryo thus comes to occupy the floor of a depression, which, relatively 
deep in front, becomes shallower posteriorly, and is surrounded by a well-marked 
lip or fold, consisting of ectoderm and somatic mesoderm, and known as the 
amniotic fold. By this time the mesodermal layers, as Avell as the endoderm, in 
their extension over the inner surface of the blastodermic vesicle, have reached 
its lower pole, where they fuse together, and, the coelomic cavities extending pari 
passu with the mesoderm, the extra-embryonic portion of the vesicle becomes 
throughout its entire extent double-Avalled, the outer wall being composed of the 
original wall of the vesicle (which may be regarded as ectoderm) plus the somatic 
layer of the mesoderm ; while the inner wall is composed of splanchnic mesoderm 
plus endoderm. These two walls are separated by the coelomic cavity, which 
becomes relatively voluminous, the inner wall, enclosing a cavity known as the 
umbilical vesicle (Fig. 96) or yolk-sac, being separated by a considerable interspace 
from the outer wall, which is now termed the chorion. 
While these changes have been taking place the embryo has begun to constrict 
itself from the embryonic shield by a tucking in, as it were, of the wall of the 
embryonic vesicle in front and at the sides under the body of the embryo. The 
anterior portion of the embryo thus becomes cylindrical and completely shut otf 
from the yolk-sac, which, as the result of the constriction, becomes converted into 
a pyriform vesicle connected with the intestine of the embryo by a narroAV stalk. 
The constriction, continuing to develop from before backward, finally reaches the 
posterior end of the body, where it wraps itself around the connection of the 
embryo with the surface of the embryonic vesicle, converting this connection into 
a stalk known as the belly-stalk or Bauchstiel. In its passage backward the con- 
striction carries with it the yolk-sac, which thus becomes enclosed within the 
belly-stalk, as does also a small evagination of the ventral wall of the intestine 
of the embryo, situated behind the attachment of the stalk of the yolk-sac, and 
known as the allantois, a rudiment of a structure of considerable size in some of 
the lower mammalia and in the birds and reptiles, where it functions as an 
embryonic respiratory organ. In the subsequent development the belly-stalk 
elongates greatly, its cavity, which is continuous with the coelom of the embryo, 
becoming filled by a peculiar mesodermal, jelly-like connective tissue, the Wharton- 
ian jelly, in which are imbedded the rudimentary allantois, the umbilical vesicle, 
and certain blood-vessels, the whole forming what is termed the umbilical cord, 
the outer end of which comes into intimate relation with the walls of the uterus, 
forming the placenta (Fig. 96, B). 84 
EMBRYOLOGY. 
It has been seen that the depression of the embryo into the embryonic vesicle 
gives rise to the formation of an amniotic fold. * As the constriction of the 
embryo from the embryonic shield progresses, this fold increases in size, and 
eventually its lips unite at the outer end of the belly-stalk, the depression in 
which the embryo lies being thus converted into a closed cavity, the amniotic 
Amniotic fold> 
Hypoblast 
Umbilical vesicle 
Ccelomic cavity 
Amniotic fold 
Umbilical. 
vesicle 
Placentav 
Allantois- 
Amniotic cavity 
Ccelomic cavity 
Fig. 96.—Diagram showing the formation of the belly-stalk. The heavy dotted line represents the embry- 
onic portion of the epiblast, the dotted portions and broken lines the mesoblast, and the inner continuous 
line the hypoblast. 
cavity. The formation of this cavity takes place very early in the development, 
the earliest known embryo having it already completely closed; and the same 
remark applies to the formation of branched outgrowths, which develop from the 
surface of the chorion and are known as the chorionic villi. These appear at first 
over a broad equatorial zone of the embryonic vesicle, but later are developed also 
at either pole, that portion of the vesicle to which the belly-stalk is attached also 
developing them. In this last region the villi continue to develop probably 
throughout gestation, taking part in the formation of the placenta, while over 
the rest of the vesicle they atrophy during the second month of development; 
and it is thus customary to speak of the placental chorion as the chorion frondo- 
sum, while the remainder is termed the chorion Iceve. Concomitantly with the 
formation of these embryonic structures important changes take place in the 
walls of the uterus (Fig. 97). In the first place, the mucous membrane lining 
it becomes thickened, forming what is termed the decidua vera, that portion of it 
which is in contact with the chorion frondosum of the embryo becoming especially 
thick and highly vascidar, and forming the decidua serotina ; and, secondly, from 
the margin of the serotina a fold arises, which grows up around the embryo, and 
finally encloses it, forming what is termed the decidua reflexa. Into the villi of THE UMBILICAL CORD AND THE PLACENTA. 
85 
the chorion frondosum blood-vessels pass from the embryo along the umbilical 
cord, and the vessels of the decidua serotina, developing into large sinuses, have 
projecting into them the villi, the blood of the embryo being thus brought into 
such intimate relation with that of the parent that an interchange by osmosis 
through the thin walls separating the two fluids readily takes place, and the 
nutrition, as well as the respiration and excretion, of the embryo is thus provided 
for. The entire region in which the interchange takes place is termed the pla- 
—UMBILICAL CORD. 
■ TUBE. 
DECIDUA. 
REFLEXA. 
EMBRYO! 
DECIDUA VERA. 
—UTERINE WALL. 
centa, which, as has been seen, is composed of a foetal and a maternal portion 
intimately related. At birth the placenta and the other deciduae separate from 
the uterus and are cast off, forming what is known as the after-birth. 
To return now to the embryo proper. At its first separation from the embry- 
onic shield it is practically straight, but a bend soon makes itself apparent in what 
will later be the region of the mid-brain, the fore-brain being bent ventrally until 
it is almost at a right angle to the rest of the body ; and, at 
about the same time, a linear depression directed dorso-ven- 
trally appears on each side of the neck region, and gradually 
deepens until it almost unites with the cavity of the digest- 
ive tract. This depression is known as a branchial cleft, and 
is succeeded by three others which develop successively from 
before backward (Fig. 98). When the second cleft is devel- 
oped a second flexure of the embryo appears, the posterior 
portion of the body being bent dorsally. This flexure, how- 
ever, is of short duration, and leaves no permanent trace of 
its existence ; but, when the third branchial cleft forms, a 
third and more prominent flexure appears, this time a ventral 
flexure situated in the neck region, and, as the dorsal portion 
of the body also becomes curved in the same direction, the 
embryo seems to be coiled upon itself. Soon after the develop- 
ment of this neck-flexure the limbs make their appearance as simple paired, bud-like 
outgrowths from the sides of the body, and, as development proceeds, they increase 
in size, and rudiments of the fingers and toes appear. Gradually in later stages 
Fig. 97.—Diagram of gravid uterus, showing formation of deciduaj and placenta. (Testut.) 
Fig. 98. Development 
of the embryo—first month. 
(His.) 86 
EMBRYOLOGY. 
the branchial clefts disappear or are modified into special structures not seen from 
the exterior, the features are gradually developed, the neck-flexure straightens 
out, and by about the third month of development the embryo has acquired a 
distinctly human appearance. 
It will now, after this sketch of the formation of the embryo, be convenient 
to consider the development of the more important organs of the body, and these 
may be grouped according to the germ-layers from which they are principally 
formed. For convenience the development of the organs derived from the 
endoderm will first be considered. 
ORGANS DERIVED FROM THE ENDODERM. 
At the stage with which the description of the formation of the germ-layers 
ended the endoderm formed a tube closed at either end, and having connected 
with it two outgrowths, the umbilical stalk and the allantois. An examination 
of the surface of the embryo at this 
stage will show a pentagonal depres- 
sion opposite the anterior end of the 
endodermal tube (Fig. 99). This de- 
pression is the oral sinus, or stomo- 
dceum, and it is bounded in front by 
the edge of a median fold of tissue 
known as the fronto-nasal process, 
while on either side is a >-shaped 
ridge, the anterior limb of each ridge 
being termed the maxillary, and the 
posterior the mandibular process. 
The thin partition which forms the 
floor of the oral sinus soon ruptures, 
and the endodermal tube is thus placed in communication with the exterior, its 
endoderm becoming continuous with the ectoderm of the sinus. Soon after the 
mouth is thus formed the two maxillary ridges, growing toward each other, meet 
beneath the fronto-nasal process, and, in the connective tissue which they contain, 
the maxillary bones develop. From each of these bones a horizontal lamella 
grows inward, and meets with its fellow of the opposite side and with correspond- 
ing lamellae from the palatine bones behind, and the hard palate is thus formed, 
separating the original mouth-cavity into an upper or nasal and a lower or oral 
portion, these two cavities communicating behind with the upper or pharyngeal 
part of the intestinal tube. 
FRONTO-NASAL' 
PROCESS. 
OLFACTORY^ 
PIT. 
JVIAXILLARY 
PROCESS. 
MANDIBULAR PROCESS I 
Fig. 99.—Development of the face. (Testut.) 
The Teeth and Salivary Glands. 
As early as the sixth week of development there appears, dipping into the 
lower and upper surfaces respectively of the maxillary and mandibular processes, 
a thickening of the ectoderm, whose cells subsequently arrange themselves into 
an anterior and posterior layer, the space which appears between these layers 
becoming the groove between the lip and the gum (Fig. 100). From the poste- 
rior layer a horizontal ridge grows inward into the substance of each gum, 
forming the dental shelf, and upon the under or upper surface of each shelf ten 
thickenings arise, each of which forms a more or less globular mass of cells, the 
enamel organ, connected with the dental shelf only by a narrow neck which ulti- 
mately disappears. In the mesoderm beneath each organ a rapid proliferation of 
cells forms a papilla, over which the enamel organ is folded like a cup, those cells 
of the papilla which are in contact with the enamel organ becoming, like the outer- 
most cells of the latter, cylindrical, and forming the odontoblasts, whose office it is 
to deposit the dentine between themselves and the enamel organ. This they begin 
to do at about the end of the fourth month of development, and at about the same BRANCHIAL CLEFTS AND STRUCTURES DERIVED FROM THEM. 
87 
time the enamel begins to be formed by the lower ends of the deeper layer of cells 
of the enamel organ becoming transformed into calcareous prisms. Finally, around 
the outside of that portion of the papilla which is not covered by the enamel organ 
ENAMEL ORGAN- 
-DENTAL SHELF 
ENAMEL ORGAN- 
•PAPILLA 
ENAMEL. 
-DENTAL SHELF 
DENTINE- 
ODONTOBLASTS- 
PAPILLA- 
L-dental shelf 
—MILK TOOTH 
—PERMANENT TOOTH 
Fig. 100—Diagram of the development of a tooth. 
there appears, about the fifth month, a deposition of bony matter derived from 
mesodermal cells and constituting the cement. 
After the separation of the anlagen of the milk teeth from the dental shelf 
the latter continues to sink deeper into the substance of the jaw, and opposite 
each milk tooth a second enamel organ arises from it, and, mesodermal papillae 
also forming as before, the anlagen of the permanent incisors, canines, and pre- 
molars are formed. The permanent molars arise in a similar manner from a 
lateral extension of the dental shelf, and as soon as all the anlagen are formed 
the tissue of the shelf in the intervals between the various teeth begins to disap- 
pear, occasionally, however, persisting in irregular masses until adult life, and 
producing various abnormalities. 
In addition to the teeth certain glandular structures develop from the epithe- 
lium of the oral cavity, the most important of which are the salivary glands, 
which arise as simple tubular evaginations, and gradually, by branching, become 
more and more complicated. 
The Branchial Clefts and the Structures derived from Them. 
At each side of the pharynx there are, as already stated, four furrows (Fig. 99), 
represented internally by corresponding depressions, so that along each furrow the 
pharyngeal epithelium is in contact with the ectoderm of the surface of the body. 
In the lower vertebrates actual perforation of the thin membrane so formed occurs, 
forming the gill-slits, but in birds and mammals the perforations do not develop. 
The first furrow lies immediately behind the mandibular process, and between the 
members of each successive pair of furrows is a thickened ridge, constituting a 
branchial arch, each arch being homologous with the maxillo-mandibular pro- 
cesses, which really represent the first arches, the mouth being the first branchial 
cleft. As development progresses the second arch of each side grows more rapidly 
than the others, which are in consequence pushed inward toward the median line, 
and a deep depression is formed at the side of the neck, the sinus prcecervicalis. 
From the posterior edge of the second arch a fold grows backward over the 
mouth of this sinus, and eventually completely covers it in by uniting posteriorly 
with the side of the body. 88 
EMBRYOLOGY. 
From or in connection with the branchial arches or clefts a number of struc- 
tures develop, some of which may be considered here. From the epithelium of 
the fourth pair of clefts two thickenings develop, and subsequently fuse together, 
the single mass so formed growing backward toward the pericardium, separating 
from the clefts, and enlarging by branching at its posterior end. It forms the 
thymus gland, whose epithelial anlage becomes early infiltrated with lymphatic 
tissue, and which, subsequent to the second year after birth, begins to undergo 
degenerative changes. The thyroid gland arises partly from the last pair of clefts 
as paired hollow evaginations, and partly from a median evagination of the floor 
of the pharynx in the vicinity of the second branchial arch. These anlagen early 
fuse together, and the gland usually loses all connection with the pharynx, the 
foramen caecum at the base of the tongue representing, however, the place of the 
origin of the median anlage. 
The tongue is, embryologically, partly a product of the pharyngeal region, and 
arises from two anlagen. Its anterior portion arises as a thickening of the floor 
of the oral cavity, its back portion, however, developing as a pair of thickenings 
situated in the vicinity of the second and third branchial arches. These thicken- 
ings extend forward and outward, forming a V-shaped mass, which encloses in 
front the posterior end of the anterior anlage. The junction of the two anlagen 
is indicated in the adult by the V-shaped groove in which the circumvallate 
papillae are situated, the foramen caecum, already referred to in connection with 
the thyroid gland, lying at the apex, of the groove. 
The Trachea and Lungs. 
Below, the pharynx communicates with the tubular oesophagus, and on the 
inner surface of the upper part of this there early appears a longitudinal groove, 
from the lower end of which two pouch-like outgrowths develop. As soon as 
these begin to form the groove begins to be constricted from below upward from 
the oesophagus, and becomes the trachea and larynx, the constriction not contin- 
uing to complete separation, so that the larynx communicates above with the 
pharynx. In the connective tissue of the walls of the trachea cartilaginous 
rings develop, the uppermost of which form the cricoid and arytenoid cartilages 
of the larynx, the thyroid cartilage being produced by the fusion of the ventral 
ends of two pairs of cartilaginous bars which are primarily developed in the 
mesoderm of the fourth and fifth branchial arches. The pouch-like outgrowths 
are the anlagen of the lungs, and at an early stage become lobed, three lobes 
appearing in the right lung and two in the left. Secondary and tertiary saccula- 
tions later appear, and the complicated structure of the adult lung is acquired. 
It is to be noted that the epithelium of the lungs, trachea, and larynx is of 
endodermal origin. 
The Intestine and Mesenteries. 
From that portion of the primitive intestine which succeeds the oesophagus, 
the stomach and intestines, together with the liver and pancreas, develop. Of 
the two structures which in early embryonic life are connected with it, the allan- 
tois early separates, its intra-embryonic portion persisting as the urinary bladder 
and the urachus, while the stalk of the umbilical vesicle retains its connection 
until after birth, the intra-embryonic portion of it occasionally persisting even 
into adult life as a more or less pronounced diverticulum of the lower part of the 
small intestine, known as Meckel’s diverticulum. 
At first the intestine is a simple straight tube attached to the dorsal wall 
of the abdominal cavity by a dorsal mesentery, formed by the reflection over it 
of the peritoneal lining of the abdominal coelom. Its upper portion is also 
attached to the anterior wall of the abdomen by a ventral mesentery, whose 
lower border is falciform in shape, and is attached to the abdominal wall at the 
umbilicus. This simple arrangement, however, soon disappears, as the intestine, THE INTESTINE AND MESENTERIES. 
89 
growing in length more rapidly than the cavity in which it lies, is pushed out 
into a loop, as is represented in Fig. 101. The elongation continuing, the loop 
AURICLE. 
-OESOPHAGUS. 
PERICARDIUM. 
-SMALLER OMENTUM 
SEPTUM 
transversum: 
'SPLEEN. 
LIVER. 
-STOMACH. 
-M ESOGASTR I UM 
LIG. OF LIVERT 
-PANCREAS. 
DUODENUM. 
UMBILICAL 
VEIN.N< 
-MESENTERY 
-MESOCOLON. 
YOLK STALK, 
■COLON. 
Fig. lOl.—Diagram of the human mesentery in its primitive relations. (C. S. Minot.) 
bends upon itself, that portion of the intestine which will become the transverse 
colon passing over the portion which is to become the duodenum. During the 
elongation of the intestine the edge of the dorsal mesentery which is attached to 
it undergoes a corresponding increase in length, while at the line of attachment 
to the body-wall it increases but slightly, the mesentery of the loop in conse- 
quence assuming a fan-like form, and, when the twisting of the loop supervenes, 
becoming funnel-like. 
By this time a differentiation of the intestinal tube has occurred, the portion 
of it above the loop becoming enlarged to form the stomach, while the portion ot 
the loop which passes transversely across the abdominal cavity and the portion of 
the intestine below this becomes the large intestine. The caecum develops as an 
outgrowth from the large intestine at the point where it is joined by the small 
intestine, and the vermiform appendix is an outgrowth from the caecum. The 
Diaphragm 
■Liver 
Lesser omentum 
Stomach 
Pancreas 
Greater curvature 
Anterior lamella of greater omentum 
Posterior lamella of greater omentum 
Transverse mesocolon 
Duodenum 
Transverse colon 
Mesentery 
Greater omentum 
Small intestine 
Fig. 102.—Diagram to illustrate the history of the human mesentery—earlier stage. (Hertwig.) 
further changes in the intestine consist principally of a continued elongation, 
especially of the small intestine, and of the occurrence of fusion and degeneration 
of certain portions of the mesentery. Thus, the mesentery attached to the trans- 
verse colon, primarily radiating from the apex of the mesenterial funnel, latci 90 
EMBRYOLOGY. 
extends its insertion laterally upon the body-wall, forming a transverse sheet, the 
mesocolon. This passing over the duodenum binds it fast to the posterior wall of 
the abdomen, and as a result the duodenal mesentery degenerates. The ascending 
and descending colon likewise come to lie in contact with the abdominal wall, and 
their mesentery degenerates to a certain extent, their lower portions being only 
covered, and not enclosed, by peritoneum. 
The stomach, in the mean time, has also been undergoing certain changes in 
position. At first it is straight, what later becomes the small curvature being 
directed anteriorly; but soon its pyloric end shifts over toward the right side of 
the body, and, at the same time, the entire structure twists in such a manner that 
its original left surface becomes anterior, and the small curvature is directed to 
the right.1 As the result of this the portion of the dorsal mesentery which is 
attached to the stomach becomes thrown into a pouch lying behind the stomach, 
the cavity of the pouch forming the omental cavity, and its floor later being drawn 
downward to form the great omentum, the posterior layer of which, as it passes 
back to the body-wall, fuses with the mesocolon. 
During the progress of these changes a pair of outgrowths have been develop- 
ing from the duodenum and passing forward between the two layers of the ventral 
mesentery. They unite to form the liver, which quickly reaches a large size—so 
large, in fact, that the two layers of the mesentery cannot quite meet around it. 
'Diaphragm 
-Liver 
-Lesser omentum 
Greater curvature 
Stomach- 
-Pancreas 
-Part of omentum enclosing pancreas 
~ Transverse mesocolon 
~Duodenum 
Posterior lamella of greater omentum■ 
Transverse colon 
-Mesentery 
Greater omentum■ 
Small intestine 
Fig. 103.—Diagram to illustrate the history of the human mesentery—later stage. (Hertwig.) 
but are reflected from its sides as the coronary ligaments. The upper portion of 
the mesentery, above the liver, remains unchanged, however, forming the falciform 
ligament, while the portion below is affected by the torsion of the stomach, so that 
its faces come to lie dorsally and ventrally, instead of right and left, and it forms 
the small omentum (Figs. 102, 103). 
The liver arises as a pair of hollow outgrowths from the ventral surface of the 
upper part of the duodenum. Each outgrowth, which represents one of the lobes 
of the adult liver, becomes greatly complicated by the development of numerous 
lateral solid branches, these developing others, and so on, the various branches 
uniting with one another to form a network in the meshes of which are found 
capillary blood-vessels. The solid branches, termed hepatic cylinders, become 
converted partly into bile-ducts and capillaries by hollowing out, and partly into 
the liver parenchyma, the original network becoming more or less inconspicuous. 
The various bile-capillaries unite to form the right and left hepatic ducts, which 
The Liver and Pancreas 
1 It may be pointed out that this twisting is the cause of the position of the pneumogastric nerves 
in their course over the stomach in the adult, the left nerve passing in front of and the right nerve 
behind the viscus. ORGANS DERIVED FROM THE MESODERM. 
91 
at first open separately into the duodenum; but later the duodenum becomes 
pouched where they enter, and this pouch is drawn out to form the common bile- 
duct, from which the gall-bladder and cystic duct arise as a hollow evagination. 
The pancreas arises as a hollow evagination of the dorsal wall of the duode- 
num opposite the point where the liver anlagen appear, and grows dorsally between 
the two layers of the dorsal mesentery, gradually becoming very much branched. 
It is affected by the torsion of the stomach, so that it assumes a transverse posi- 
tion in the abdominal cavity, and on the development of the mesocolon is pushed 
with the duodenum against the dorsal wall of the abdomen, its mesentery in con- 
sequence undergoing degeneration. Its duct, which at first is attached to the 
dorsal surface of the duodenum, gradually moves around toward the ventral 
surface, and finally, as a rule, unites with the common bile-duct. 
ORGANS DERIVED FROM THE MESODERM. 
The primitive layers of the mesoderm have their cells arranged at first in an 
epithelial manner, and this arrangement is preserved by certain portions of the 
layers for a considerable time, even, it may be, throughout life; to these portions 
the term mesothelium may be applied. At certain regions, however, cells are 
budded off from the primitive layers to form irregular masses, or become scat- 
tered throughout the body without any definite arrangement; and these cells are 
termed mesenchyme. It is possible, in accordance with this division of the 
mesoderm, to recognize mesothelial and mesenchymatous organs. 
From the mesenchyme are derived the connective and supportive tissues of 
the body, whose histological differentiation need not be considered here. A few 
statements may be made, however, concerning the development of the skeleton. 
The first trace of a supportive structure in the embryo is the notochord, (Fig. 104), 
The Skeleton. 
MUSCLE PLATE 
SPINAL GANGLION. 
SPINAL CORD. 
SOMATIC MESODERM. 
CARDINAL VEIN. 
AMNION. 
NOTOCHORD. 
f AORTA. 
SPLANCHNIC MESODERM. 
ENDODERM. 
whose formation has already been described, and which is practically a transitory 
structure, being replaced later by the spinal column and skull. From a portion 
ot each of the mesodermal somites a mass of cells is budded off, and these masses 
arrange themselves on either side of the notochord, which they eventually enclose, 
growing dorsally at the same time around the spinal cord. In the intervals between 
the members of each pair of mesodermal somites each mesenchymatous mass begins 
0 e transformed into cartilage, which later ossifies to form the vertebral centrum; 
an , as the ossification proceeds, the portions of the notochord enclosed by the 
Fig. 104.—Cross-section of embryo. 92 
EMBRYOLOGY. 
centra are gradually encroached upon and finally disappear, the intervening por- 
tions persisting as the gelatinous substance of the intervertebral disks. The neural 
arches develop a little later than the centra, and ossify separately, uniting with the 
centra only after birth. 
The ribs arise by the chondrification and subsequent ossification of the mesen- 
chymatous tissue situated between the members of each pair of mesodermal 
somites, the ribs of the thoracic region being, however, the only ones which 
undergo complete development, extending in the wall of the body to the ventral 
surface, where a number of them unite to form the sternum. In the other portions 
of the trunk and in the neck they remain small, and become united with the ver- 
tebra, being represented in the cervical region by the ventral portions of the 
transverse processes, in the lumbar region by the costal processes, and in the 
sacrum by the lateral masses. 
The skull shows from the beginning no trace of being composed of distinct 
vertebra, except in the occipital region. The first trace of the skull is found 
in two cartilaginous bars, placed one on each side of the anterior end of the noto- 
chord. These are the parachordal 
cartilages (Fig. 105), and in front 
of them two other cartilages 
known as the trabeculce cranii 
are formed. These four carti- 
lages eventually unite together, 
and the trabeculae uniting at their 
anterior extremities to form a 
plate, known as the ethmo-vorner- 
ine plate, a cartilaginous basis 
cranii is formed, which later ex- 
tends dorsally behind and at 
the sides, leaving, however, the 
greater portion of the brain cov- 
ered only by membrane. About 
the third month of development 
centres of ossification begin to 
appear in this chondro-cranium, 
resulting in the formation of a 
number of separate bones, which 
later fuse with one another to a 
certain extent to form the occipital, sphenoid, and ethmoid bones, all of which 
are really composite bones. 
In addition to the bones which are thus developed, other elements occur 
in the skull and may be arranged in three groups ; (I.) A number of bones 
are developed without being preformed in cartilage, their osseous matter being 
deposited directly in fibrous connective tissue. In this way—as membrane bones, 
as they are termed—are formed the parietals and frontals and the bones of the 
face, such as, for example, the nasals, malars, lachrymals, palatines, and maxillae. 
(II.) Around each auditory organ a cartilaginous case, the periotic capsule, devel- 
ops, quite independently of the primary chondro-cranium, filling up a gap in its 
walls on each side between the occipital and sphenoid bones, and from it are 
formed the petrous and mastoid portions of the temporal, the squamous and 
tympanic portions being membrane bones, which secondarily unite with the cap- 
sule. (HI-) In each branchial arch a cartilaginous bar develops, these bars 
forming what is termed the visceral skeleton, and certain of them become 
intimately related to the skull. The dorsal end of the maxillo-mandibular 
cartilage becomes entirely replaced by membrane bones, the maxillae, palatines, 
and internal pterygoid plates of the sphenoid; while its lower end, known as 
Meckel’s cartilage, ossifies and unites with a number of membrane bones, which 
enclose it, to form the lower jaw or mandible, and also takes part in the formation 
.OLFACTORY PIT. 
•TRABECUL/E CRANII. 
-PALATO-PTERYGOID 
, CARTILAGE. 
-MECKEL'S CARTILAGE 
, (mandibular). 
-HYPOPHYSIS. 
-HYOID CARTILAGE. 
FOR 
NERVE. 
'PE RIOTIC 
'CAPSULE 
.FOR GLOSSOPHARYNGEAL 
A NERVE. 
NOTOCHORD 
PARACHORDAL 
CARTILAGE. 
Fig. 105.—Cranial cartilages of embryo. (C. S. Minot, after W. 
K. Parker.) THE HEART AND BLOOD-VESSELS. 
93 
of the ossicles of the middle ear. The cartilages of the second and third arches 
unite to form the hyoid bone, the small horn, the stylo-hyoid ligaments, and the 
styloid processes of the temporals representing the complete second arch, while 
the great horn represents the incomplete third arch. The fourth and fifth arches 
become greatly reduced, and fuse together, as already indicated, to form the thyroid 
cartilage of the larynx. 
The hones of the extremities are all preformed in cartilage, and for the long 
bones at least two or three centres of ossification are usually present, one being 
for the shaft and one for each epiphysis, these latter, however, being merely 
provisions for the growth in length of the bone, and not representing originally 
distinct bones. In the scapula, however, two primary centres are formed, one for 
the greater portion of the bone, and one for the coracoid process, which in the 
lower vertebrates is a distinct bone; and similarly three primary centres are found 
in each hip-bone, one for the os pubis, one for the ischium, and one for the ilium, 
each of these being primarily a distinct bone. In the carpus and tarsus certain 
fusions also occur. Typically, each consists of nine bones arranged in a proximal 
row of three bones, a distal row of five bones, and a single bone between the two. 
The following scheme will show the fusions which have taken place, each composite 
bone ossifying from two centres, the rest from one : 
, A _ 
' \ 
Scaphoid, Radiale. 
Semilunar, Intermediate. 
Cuneiform, Ulnare. 
(Fused with Scaphoid) Centrale. 
Trapezium, Carpal I. 
Trapezoid, “ 11. 
Os Magnum, “ HI. 
Unciform, u 
Carpus. 
Tarsus. 
Tibiale, 1 . , , 
Intermediate, j -Astragalus. 
Fibnlare, Calcanenm. 
Centrale, Navicular. 
Tarsal 1., Internal Cuneiform. 
“ 11., Middle Cuneiform. 
u 111., External Cuneiform. 
“ IV 1 
u-y ’’ > Cuboid. 
_ The pisiform does not belong to the same category as the other carpal bones, 
being an ossification in the tendon of the flexor carpi ulnaris, just as the patella 
is an ossification in the tendon of the quadriceps extensor femoris. Such bones 
are known as sesamoid bones. 
The Heart and Blood-vessels. 
It has already been seen that the formation of the blood-vascular system 
begins in the area opaca of the blastodermic vesicle, and thence extends toward 
the embryo, two vessels, the vitelline veins, carrying the blood from the yolk-sac 
to the embryo. While the embryo is still spread out flat upon the surface of the 
blastodermic vesicle the splanchnic layer of the mesoderm on each side of the 
body buds off a small collection of cells (Fig. 106, endocardium) into the space 
between it and the endoderm ; these early arrange themselves in a tubular form, 
and become enclosed within a fold of the splanchnic mesoderm. This folds 
(Fig. 106, myocardium), and tubes so formed are the anlagen of the heart, the 
two halves of which are at first widely separated; but as the embryo becomes 
constricted off from the yolk-sac they are brought nearer together, and finally 
unite to form a single double-walled tube, the folds becoming the muscular walls 
of the heart, while the mesenchymatous tubes form its endocardium. 
The heart, thus formed, is situated in the neck region of the embryo, and has 
communicating with it behind the vitelline veins, while anteriorly it is continued 
into the aortic trunk. This simple tubular heart now undergoes a considerable in- 
crease in length, and, as a result, bends upon itself in an S-shaped manner (Fig. 107), 
the aortic end being ventral to the venous. The venous end now begins to enlarge, 
and pouches out into a sac on each side, forming the right and left auricles; and 94 
EMBRYOLOGY. 
from its dorsal wall between the two auricles a vertical partition begins to form, 
which, growing backward toward the horizontal portion of the heart, would sep- 
arate the auricles completely were it not that a foramen forms in its upper part 
SPINAL CORD— 
BODY CAVITY 
SOMATIC LAYER 
MYOCARDIUM 
NOTOCHORD 
'pharynx 
'SPLANCHNIC LAYER 
ENDOCARDIUM 
SPINAL CORD 
-PHARYNX 
BODY CAVITY- 
MYOCARDIUM-2 
SOMATIC LAYER 
ENDOCARDIUM' 
NOTOCHORD 
■SPLANCHNIC LAYER 
SPINAL CORD- 
•AORTIC ARCH 
BODY CAVITY 
NOTOCHORD 
iSOMATIC LAYER 
ENDOCARDIUM 
'SPLANCHNIC LAYER 
Pig. 106.—Development of the heart: cross-sections of the cervical region of an embryo; diagrammatic. 
(Testut.) 
(the foramen ovale), which persists until birth, closing normally shortly thereafter. 
The partition passes to the left of the opening by which the blood from the vitelline 
AURICLE 
AURICLE 
.ARTERIAL- 
BULB 
AURICLES 
Jauri- 
Lcle 
VENOUS 
END 
VENOUS 
END 
; 
VENTRICLE 
VENTRICLE 
Fig. 107.—Four stages in the development of the heart: front view ; diagrammatic. (Testut.) 
veins flows into the heart, and, consequently, this opening now communicates with 
the right auricle, the left receiving four small veins which come to it from the lungs. 
The point of union of the auricular and ventricular regions has in the mean 
time become considerably constricted, and the auricular septum extends far enough THE HEART AND BLOOD-VESSELS. 
95 
downward to divide the opening between them into two parts. In the ventricle 
a crescentic partition develops from the posterior and dorsal walls, and grows 
upward toward the auricular septum, with the lower border of which it unites, 
ending, however, in a free edge beneath the opening by which the aortic trunk 
communicates with the ventricle. The aortic trunk has meanwhile flattened 
dorso-ventrally, and on the inner surfaces of the flat sides two ridges develop, 
and finally unite, dividing the lumen of the aortic trunk longitudinally into two 
portions (Fig. 108). The partition extends down into the ventricle, and unites 
AORTIC TRUNK 
auricuIo- 
'VENTRICULAR/ 
\ OPENING /i 
CRESCENTIC 
FOLD 
LEFT 
VENTRICLE 
RIGHT VENTRICLE 
LEFT 
VENTRICLE 
PULMONARY. 
ARTERY 
AORTA 
LEFT AURICULO* 
C VENTRICULAR OPENING 
RIGHT AURICULOy 
VENTRICULAR /> 
OPENING 
-LEFT VENTRICLE 
RIGHT VENTRICLES. 
Fig. 108.—Development of the aorta and pulmonary artery. (After Born.) 
with the free edge of the ventricular septum, so that the division of the ventricle 
becomes complete, and the aortic trunk then separates completely into two tubes, 
one of which, the aorta, communicates with the left ventricle, while the other, the 
'pulmonary artery, opens into the right ventricle. The original tubular heart has 
thus become converted into a four-chambered organ which differs from the adu t 
heart only in the existence of the foramen ovale in the auricular septum. 
The aortic trunk, prior to its division, in passing forward from the heart gives 
off from time to time pairs of lateral branches, which pass dorsally in the branchia 
arches. These are the aortic arches, which, on each side, unite above the branchial 
clefts to form a longitudinal vessel, and this, passing backward, unites with its fellow 
of the opposite side to form the dorsal aorta (Figs. 109,110). This primitive con- 
dition is, however, merely transitory, the first arches early disappearing, and then 
the second, the continuations of the aortic trunk from which these arches arise per- 
sisting, however, to form the external carotid arteries, while the branches of the 
dorsal aorta into which they opened likewise persist to form the internal carotids. 
The third arches persist, becoming portions of the internal carotids, and forming 
the connections between those arteries and the external carotids ; but the portions 
of the branches of the dorsal aorta which intervene between the third and fourth 
arches disappear, thus cutting off the direct connections of the internal carotids 
with the dorsal aorta. The fourth arch of the left side persists in its entirety, 
forming the arch of the aorta of the adult, and is the only connection between 
the heart and the dorsal aorta, since the right branch of the dorsal aorta disap- 
pears completely behind the third arch, the right fourth arch forming part of the 
right subclavian artery. The fifth arches give rise to an artery on each side, the 
pulmonary arteries, and the portion of the arch distal to the branch on the right 96 
EMBRYOLOGY. 
side disappears, but persists on the left side to form the ductus arteriosus, uniting 
the pulmonary artery with the dorsal aorta—a connection functional for the 
passage of blood up to birth, but aborting later. 
RIGHT 
ARCHES 
LEFT 
ARCHES 
EXTERNAL 
CAROTID 
INTERNAL 
CAROTID 
SUBCLAVIAN- 
DUCTUS 
ARTERIOSUS 
VERTEBRAL 
PULMONARY 
DORSAL 
AORTA 
AORTA 
Fig. 109.—Aortic arches, early arrange- 
ment. (After Rathke.) 
Fig. 110.—Aortic arches, final condition. (After Eathke.) 
Of the venous system it has already been seen that there is a pair of vitelline 
veins coming from the yolk-sac and opening into the venous end of the embryonic 
heart. In addition to these, other veins are developed at an early period, which 
unite together and with the vitelline veins before entering the heart, forming a 
sinus venosus, which later is taken up into the right auricle. Of these veins there 
are, first, the umbilical veins, which bring back the blood from the placenta, enter- 
ing the body of the embryo at the umbilicus (Fig. 111). The left umbilical vein 
Fig. 111.—Development of the veins; A, primitive condition, bilateral symmetry; B, formation of portal 
system; C, final condition; diagrammatic. 1, sinus venosus; 2, right ductus Cuvieri; 2', left ductus Cuvieri; 3, 
right jugular vein; 3', left jugular vein ; 4, cardinal vein; 4', vena azygos major; 5, vitelline vein; 6, umbilical 
vein; 6', umbilical vein in cord; 7, portal vein; 8, liver; 9, ductus venosus; 10, vena cava inferior; 11, common 
iliac vein; 12, vena hemiazygos; IS, left hrachio-cephalic vein; 14, coronary sinus; 15, veins of lower limbs. 
Atrophied parts in broken lines. (Testut.) 
degenerates later almost entirely, but the right passes forward in the ventral mid- 
line of the abdomen to the under surface of the liver, to which it distributes blood, 
continuing onward, however, to open into the sinus venosus. During embryonic 
life this vein increases in size, the vitelline veins, on the other hand, becoming 
smaller and, forming connections with one another, eventually giving rise to the 
portal vein. After birth, however, as soon as the placental circulation ceases, the THE DIAPHRAGM. 
97 
umbilical vein becomes converted into a solid cord of tissue, which, from the 
transverse fissure of the liver to the umbilicus, is known as the round ligament, 
while the portion above this becomes the ductus venoms, the uppermost part 
persisting as the upper part of the vena cava inferior and receiving the hepatic 
veins. 
Secondly, there are two other pairs of veins which are entirely confined to the 
embryo—the jugulars, which bring back to the heart the blood from the head and 
upper'extremity, and the cardinals, which return the blood from the trunk and 
lower limb, the jugulars and cardinals of each side of the body uniting together 
before opening into the sinus venosus to form a transverse branch, the ductus 
Cuvieri. As the embryo develops the jugulars increase in size more rapidly than 
the cardinals, so that the Cuvierian ducts seem to be the continuations of the jugu- 
lars; and when the sinus venosus is taken up into the right auricle the two Cuvier- 
ian ducts aud the umbilical vein, which open into the sinus from the right and 
left sides and from below, respectively, come to have separate openings into the 
auricle, forming the three principal openings found in the adult. 
The cardinal veins do not, however, persist until adult life in their original 
condition, but are to a certain extent replaced by an unpaired venous trunk, the 
vena cava inferior, which makes its appearance in the tissue between the two primi- 
tive kidneys, and early unites with the cardinals by means of transverse branches, 
through which it receives the blood from the kidneys and rapidly increases in 
size. In the mean time, a connecting trunk has formed between the left and 
right cardinals, and the main mass of the blood from the left lower limb flows over 
into the right cardinal, which thus becomes enlarged and forms apparently the 
continuation of the inferior vena cava. Above, the vena cava opens into the 
umbilical vein, on the degeneration of the umbilical after birth, this upper- 
most part of it persists as the upper end of the vena cava. This vessel is, there- 
fore, composed of three originally distinct parts : (1) the independent trunk 
between the primitive kidneys ; (2) the lower end of the right cardinal vein; 
and (3) the uppermost part of the umbilical. When completely formed it receives 
the blood from the greater part of the territory originally drained by the cardi- 
nals, the upper portions of these latter still continuing, however, to receive the 
blood from the intercostal spaces of the thorax. The lower part of the left car- 
dinal completely disappears, and it also loses its connection with the left ductus 
Cuvieri, forming instead a transverse connection with the right cardinal, and 
becoming the vena; hemiazygos (azygos minor) of adult anatomy, the upper part 
of the right cardinal becoming the vena azygos m,ajor. 
In the mean time, a slight change has taken place in the jugulars, a branch 
passing across from the left to the right, and forming the left brachio-cephaUc vein 
of the adult, which receives and passes over to the right jugular all, the blood 
returning by the left jugular. As the result of this the portion of the left jugular 
between the origin of the left brachio-cephalic vein and the left ductus Cuvieri be- 
comes greatly reduced, being represented in the adult only by the small oblique vein 
on the back of the left auricle ; but the left ductus Cuvieri, thus separated from both 
the jugular and the cardinal vein which originally opened into it, does not degen- 
erate, since it still receives a large proportion of the blood returning from the tissue 
of the heart itself through the coronary veins, but persists as the coronary sinus. 
The Diaphragm. 
Closely associated with the development of the venous trunks is the formation 
of the diaphragm. At first the body-cavity or coelom is a continuous cavity extend- 
ing the entire length of the trunk, and even into the head region ; but during 
development the portions in the head and neck disappear, the thoracic and 
abdominal portions persisting, and being at first continuous. After the heart 
has formed, however, a thick transverse partition, the septum transversum, begins 
to grow from the ventral and lateral walls of the body toward the sinus venosus, 98 
EMBRYOLOGY. 
enclosing the venous trunks which open into the sinus. By its formation the 
thoracic and abdominal portions of the coelom are almost completely separated, 
the only communication between them being by a pair of small canal-like open- 
ings, one on each side of the dorsal mesentery; and, as the lungs develop, they 
push the walls of five canals in front of them, these walls thus forming the pleurae. 
At a comparatively early stage of development the pericardial portion of the 
thoracic cavity becomes separated from the pleural portions ; and considerably 
later the latter become cut otf from the abdominal cavity, then known as the 
peritoneal cavity, by the growth forward from the dorsal wall of the body of a 
partition which unites with the free edge of the septum transversum. 
The Lymphatic Vessels, the Spleen, and the Suprarenal Capsules. 
Of the development of the lymphatic vessels comparatively little is known with 
certainty, though they seem to be formed similarly to the blood-vessels by a hol- 
lowing out of strands of mesenchymatous cells. The mode of development of 
the spleen is also but imperfectly known : it arises as a collection of mesenchyma- 
tous cells situated between the layers of the dorsal mesentery of the stomach, and 
early receives a rich supply of blood-vessels. 
The suprarenal bodies arise as two distinct portions, one of which is derived 
from a collection of mesenchymatous cells in the vicinity of the inferior vena 
cava, and gives rise to the cortical portion of the organ ; while the other originates 
from the anlagen of the abdominal sympathetic ganglia and forms the medullary 
portion. The significance of these organs is, however, not yet understood. 
The Muscular System. 
From the mesothelial portions of the mesoderm the voluntary muscles and 
the urino-genital system develop. The voluntary muscles are derived from the 
mesodermal somites, the greater portions of which become transformed into mus- 
cle-tissue, and, consequently, the voluntary musculature has primarily a segmental 
arrangement, consisting of a series of muscle-plates placed one behind the other 
on each side of the body, and extending forward even into the head-region of the 
embryo. Each plate is supplied by a cranial or a spinal nerve, and has the fibres 
of which it is composed directed longitudinally, and arising from and inserted 
into the connective-tissue membranes which separate each pair of plates. This 
primitive arrangement, however, is not long retained, the various muscle-plates 
fusing together to a greater or less extent, and dividing longitudinally and into 
various layers, and so producing the complicated muscular system ot the adult. 
The involuntary muscle-tissue which occurs distributed through the walls of 
the various viscera seems to arise by the differentiation of mesenchymatous cells, 
and to have nothing to do with the mesodermal somites. 
The Excretory and Reproductive Organs. 
The excretory and reproductive systems arise from certain of the mesodermal 
somites just where they join the splanchnic and somatic layers, and the first por- 
tion of the excretory system to appear arises from certain somites in the vicinity 
of the heart, a solid cord of cells growing out from each somite toward the ecto- 
derm. Each cord later becomes converted into a canal, which opens at one end 
into the coelom, and is connected at the other end with the ectoderm. This col- 
lection of tubules is termed the pronephros (Fig. 112), and as it develops there is 
formed from the ectoderm, along the line where the tubules are in contact with it, 
a longitudinal canal, which later separates from the ectoderm and comes to lie 
close to the mesoderm (Fig. 104). This is the pronephric or Wolffian duct, with 
which the tubules of the pronephros unite, and which opens posteriorly into the 
urogenital sinus, to be described later. THE EXCRETORY AND REPRODUCTIVE ORGANS. 
99 
The pronephros, however, is but a transitory organ, and it soon degenerates ; a 
second excretory organ, the mesonephros or Wolffian body, makes its appearance, its 
development being similar to that of the pronephros. Its tubules, which open at 
one end into the coelom and at the other into the Wolffian duct, reach a consider- 
AORTA. 
GLOMERULUS OF PRONEPHROS. 
>PRON EPHROS. 
■genitaiJ 
GLA N D. | 
/MESONEPHROS. 
GLOMERULUS. 
URETER. 
TUBULE CF 
>KIDNEY. 
BLADDER. 
WOLFFIAN, 
CANAL. 
Pig. 112.—Diagram of the various excretory organs successively developed in the formation of the urinary 
system. (Testut.) 
able length, and become much contorted, and a knot of capillary blood-vessels, 
developing in contact with each tubule, pushes its wall in front of it to form a 
glomerulus projecting into the tubule. The tubules early lose their connection 
with the coelom, and, though at first they present a strictly segmental arrange- 
ment, this is not adhered to, as secondary and tertiary tubules arise from each 
mesodermal somite, develop glomeruli, and unite with the primary tubules to 
open into the Wolffian duct. The Wolffian body thus becomes an exceedingly 
complicated organ, which, on account of its size, forms a strong projection into 
the coelom from the dorsal wall of the body. 
But even this second kidney does not persist into adnlt life as a functional 
excretory organ, but portions of it degenerate, while other parts are adapted to 
new functions, its excretory functions being assumed by a new kidney, the meta- 
nephros. This appears as a tubular outgrowth from the dorsal surface of the 
lower part of each Wolffian duct, and from the anterior end of this a number of 
tubules grow out and push their way into a mass of mesodermal tissue which has 
concentrated around them. The original outgrowths become the ureters, and the 
tubules, which become very numerous, develop into the urinary tubules, in connec- 
tion with which glomeruli (Malpighian corpuscles), derived from the mesodermal 
mass, develop. The compact organ thus formed becomes the functional kidney of 
the adult. 
When the Wolffian bodies are fully developed a cord of cells appears on the 
lateral surface of each of them, and becomes converted into a canal opening 
behind into the cloaca and in front into the coelom. This is the Mullerian duct, 
and by the time it is established a thickening of the peritoneal cells covering the 
mesial surfaces of each Wolffian body appears, forming the germinal ridges, from 
which the ovaries or testes develop. In the case of the ovaries the mesenchyma- 100 
EMBRYOLOGY. 
tons tissue immediately beneath the thickenings develop into the stroma, into 
which cords of cells (Fig. 113) grow from the thickening. Certain of the cells 
GERMINAL 
EPITHELIUM 
GERMINAL 
CORD OF CELLS 
PRIMITIVE OVULES 
IN EPITHELIUM 
---'TV 
FOLLICLE 
-VESSEL 
VESSEL- 
FOLLICLE 
ISOLATED 
■OVULES ABOUT 
TO SEPARATE 
IN FOLLICLES 
FOLLICLE CELL. 
Fig. 113.—Section of the ovary of a new-born child. (After Waldeyer.) 
of the cords enlarge greatly and become ova, the remaining cells multiplying rap- 
idly by division and becoming the follicle-cells. Division of the cells which are to 
form ova appears to cease at about the second year after birth, by which time, 
therefore, all the ova are differentiated. The testes are at first very similar to the 
ovaries, and have a similar development, the spermatic cells being derived from 
the cells of the germinal ridge, and the stroma of the ovary being represented by 
the tunica albuginea and the trabeculae of the testis. 
When mature the ova are extruded from the ovary practically into the peri- 
toneal cavity, though, as a matter of fact, they are usually received at once into 
funnel-like openings by which the Mullerian ducts communicate with the peri- 
toneal cavity, these ducts becoming the Fallopian tubes of the adult, and their 
lower portions fusing to form the uterus and vagina. In the embryo, however, 
the Mullerian ducts extend much farther forward than the position of the ovary, 
the ostium of the Fallopian tubes being a new formation and not the original 
terminal opening, the more anterior portion of each duct being probably repre- 
sented in the adult by the hydatid of Morgagni (Fig. 114), a small vesicular 
structure attached to one of the fimbriae of the secondary opening. While the 
ovary and the metanephros have been developing the mesonephros has been 
degenerating, and all those portions of the W olffian ducts which lie anterior to 
the points of outgrowth of the metanephric ducts disappear, except small portions 
at each end. The upper end, through mesonephric tubules which communicate 
with it, comes into intimate relation with the ovary, forming with its tubules the 
parovarium, which in the adult lies close to the ovary in the substance of the 
broad ligament. The lower ends of the Wolffian ducts persist as the canals of 
Gartner, situated on each side of the upper end of the vagina, while the meso- 
nephros almost completely disappears, its uppermost tubules just mentioned and 
a small portion of its lower end alone persisting, the latter forming a cyst-like struc- 
ture lying between the layers of the broad ligament, and termed the paroophoron. 
It has been seen that the ovaries appear at the level of the mesonephros— 
that is to say, well forward in the abdominal wall. This position, however, is 
not retained, but they descend as development proceeds, and finally lie in the 
pelvic cavity. This descent is partly produced by the contraction of a band of 
connective tissue which descends from the lower end of the mesonephros to be 
attached to the skin in the region where the labia majora will later appear, and 
which is represented by the round ligament of the adult. THE EXCRETORY AND REPRODUCTIVE ORGANS. 
101 
The testes and the parts in their neighborhood undergo changes comparable 
to those just described for the ovaries, the principal difference being that the 
Mullerian ducts degenerate except at their two extremities, the anterior ends per- 
sisting as a small vesicle attached to each epididymis, and known as the hydatid 
of the epididymis, while the lower ends unite together to form a small sac, which 
opens into the prostatic portion of the urethra, and is termed the sinus pocularis. 
This latter structure from its mode of formation is evidently homologous with 
the uterus of the female, and has consequently been termed the uterus masculinus. 
On the other hand, the Wolffian ducts persist, forming the vasa deferentia, and, as 
in the female, the tubules of the upper portions of each Wolffian body grow 
inward toward the testes, with which they unite, their testicular ends forming the 
tubuli recti and rete testis, while the ends connected with the Wolffian ducts form 
the epididymis. The remainder of the Wolffian bodies undergoes almost complete 
degeneration, portions, however, as in the female, persisting, and forming the 
structures known as the vasa aberrantia of die epididymis and the paradidymis 
or organ of Giraldes. 
PAROVARIUM 
.EPIDIDYMIS 
OVARY- 
HYDATID OF 
MORGAGNI 
TESTICLE- 
-HYDATID OF 
EPIDIDYMIS 
paroophoron- 
GENITAL GLANCM 
W»AN BODTI 
VASA ABERRANTIA- 
MULLERIAN DUCT 
kidney- 
-FALLOPIAN 
TUBE 
KIDNEY- 
- WOLFFIAN 
DUCT 
KIDNEY- 
-VAS DEFERENS 
URETER 
URETER 
URETER- 
BLADDER 
-CANAL OF 
GARTNER 
BLADDER, 
BLADDER 
-VESICULA 
SEMINALIS 
URETHRA- 
UROGENITAL- 
SINUS 
URETHRA- 
JUTE HUS 
MASCULINUS 
CLITORIS- 
-RECTUM 
-RECTUM ( 
PROSTATE- 
-RECTUM 
CLOACA- 
PENIS 
VAGINA 
FEMALE 
INDIFFERENT 
MALE 
Fig. 114.—Diagram of the development of the genitourinary apparatus. (Modified from Huxley.) 
The round ligament, whose contraction occasions the descent of the ovary 
mt° the pelvic cavity, since it is primarily in connection with the mesonephros, 
has naturally a representative in the male, passing from the lower end of the 
mesonephros to that region of the skin where the scrotum will develop. By its 
contraction the descent of the testis is brought about, this organ being drawn first 
into the cavity of the false pelvis, and then into the inguinal region. Here, in 
the mean time, on each side, a downgrowth of a finger-like process of peritoneum 
into the scrotum by the side of the round ligament has occurred, the downgrowth 
being preceded by prolongations of various muscular layers of the abdominal 
wall. The testes, continuing their descent, follow these peritoneal downgrowths, 
and thus come to lie within the scrotum, the peritoneal processes wrapping them- 
selves around them and forming the tunica, vaginales, the neck by which the process 
communicates with the general peritoneal cavity subsequently closing by the fusion 
ol its walls, while the remaining coverings of the testes are produced by the 102 
EMBRYOLOGY. 
muscle- and fascia-layers of the abdominal walls which preceded the peritoneal 
process. The cord, which represents the round ligament, is to be found in the 
adult in a small cord which passes from the epididymis to the wall of the scrotum, 
and is termed the gubernaculum. 
It has already been stated that the allantois does not entirely degenerate at 
birth, the middle part of its intra-embryonic portion persisting as the urinary 
bladder, and the part between this and the umbilicus becoming converted into a 
solid cord, known as the urachus. The part between the bladder and the intes- 
tine forms what is termed the urogenital sinus, and into it the Mullerian and 
Wolffian ducts open. In the development of the ureters the portions of the 
Wolffian ducts between their point of origin and the sinus are, in the male, 
gradually taken up into the sinus, so that the ureters and the vasa deferentia 
have separate openings, the former uniting with the base of the bladder, while 
the latter open into the sinus. Since the allantois is connected with the intes- 
tine, that portion of the digestive tract receives the urinary and genital products 
as well as the faeces, and thus receives the name of the cloaca (Fig. 115). At an 
early period this cloaca becomes di- 
vided by a partition into a dorsal and 
a ventral portion; this partition becom- 
“GLANS PENIS 
-GENITAL RIDGE 
-GENITAL FOLD 
-GENITAL FURROW 
LOWER LIMB 
■CLOACA 
Fig. 115. External view of the cloaca. (Hertwig.) Fig. 116.—Anlage of the penis or clitoris. (Hertwig.) 
ing gradually thicker, the dorsal portion, representing the lowermost part of the 
rectum, becomes separated from the ventral portion, the region intervening 
between the two being the 'perineum (Fig. 117). 
In the mean time, however, on each side of the urogenital opening a ridge of 
skin, the anlage of the scrotum in the male and the labia majora of the female, 
lias appeared, and between the anterior (ventral) ends ot the ridges a tubercle 
develops, along whose posterior surface a groove is formed which opens proxi- 
mally into the urogenital sinus. This tubercle is the anlage of the penis or 
clitoris (Fig. 116), and at this stage there is practically no difference between the 
male and female genitalia. In the male the lips of the penial groove now meet 
together and fuse, the groove being thereby converted into a canal continuous 
with the urogenital sinus, the canal and sinus together constituting what is 
-GLANS PENIS 
-PREPUCE 
-GENITAL FOLD 
-GENITAL FURROW 
CLANS PENIS 
-GENITAL RIDGE 
GENITAL FURROW 
-SCROTUM 
-GENITAL FOLD 
PERINEUM 
-ANUS 
RAPHE OF 
'scrotum 
-ANUS 
Fig. 117.—Formation of the perineum, separating 
the alimentary and the genito-urinary passages. 
(Hertwig.) 
Fig. 118.—Development of urethra and scrotum. 
(Hertwig.) 
termed the urethra of the adult. As a result of this closure of the groove 
the scrotal ridges of either side are brought into contact, and fuse together 
below the penis to form the adult scrotum (Fig. 118). In the female the lips ORGANS DERIVED FROM THE ECTODERM. 
103 
of the groove on the clitoris do not fuse, but become greatly enlarged and 
form the labia minora, and the labia major a remain separated by a depression 
into which the urethra, developed in this case from the urogenital sinus alone, 
and the vagina open (Fig. 119). The final arrangement of the female external 
PREPUCE 
-CLITORIS 
-LABIUM MAJUS 
■CLITORIS 
■GENITAL RIDGE 
-LABIUM MINUS 
-VESTIBULE 
OF VAGINA 
-GENITAL FOLD 
VESTI BULE 
OF VAGINA 
PERINEUM 
.ANUS 
-PERINEUM 
-ANUS 
Fig. 119.—Development of vagina. (Hertwig.) 
Fig. 120.—Development of the female external geni 
tals. (Hertwig.) 
genitalia may thus be readily compared with an early stage of development of the 
male organs, the latter undergoing a greater amount of differentiation than those 
of the female. 
ORGANS DERIVED FROM THE ECTODERM. 
Of the ectoderm the derivatives are the outer layers of the skin and its 
appendages—hairs, nails, sudoriparous, sebaceous, and mammary glands—and 
the nervous system and sense-organs. Of the former a detailed account is 
unnecessary here, but the nervous system requires due consideration. 
The Nervous System. 
As has been seen, the central nervous system makes its appearance as the 
medullary groove. As development proceeds the lips of the groove gradually 
come together, and eventually fuse, transforming the groove into the medullary 
canal, broader in front than 
behind, and running the entire 
length of the body. The cavity 
of the canal becomes the central 
canal of the spinal cord and the 
ventricles of the brain, while its 
walls become converted into the 
various parts of the central 
nervous system. 
At first the cells composing 
the walls of the canal are prac- 
tically similar, but later certain 
°t them, the neurohlasts, lying 
nearer the central canal, begin 
to proliferate rapidly, forming 
nerve-cells (Fig. 121), while the 
remainder, the spongioblasts, 
scatter themselves among the 
nerve-cells and become the 
neuroglia, some of them eventually coming to line the central canal and forming 
the ependyma (endyma). The walls of the canal also become of unequal thick- 
ness, the portions in the dorsal and ventral mid-lines becoming thin and forming 
SPONGIOBLAST 
GERMINAL^ 
CELLS 
YOUNG 
N EUROBLAST— 
SPONGIOBLAST* 
N EU RO B LAST 
AXIS 
CYLINDER 
Fig. 121.—Development of nerve-cells and neuroglia-cells in 
wall of the medullary canal. (Testut and His.) 104 
EMBRYOLOGY. 
respectively the roof-plate and the floor-plate, while each of the lateral thicker por- 
tions becomes divided by a longitudinal groove into a dorsal and a ventral zone. 
The spinal cord develops from the narrower posterior portion of the medullary 
canal, and is formed mainly by the growth of the cells of the ventral zones, the 
dorsal zones being represented only by the dorsal horns of the gray matter, 
while the parts contributed by the roof- and floor-plates are comparatively insig- 
nificant. At an early period a series of constrictions, separated from one another 
by definite intervals, appear throughout its entire length, and give it the appear- 
ance of being composed of a series of segments, which are termed neuromeres, and 
to each of which a pair of nerves corresponds. The existence of the constrictions 
is, however, transitory, and it is probable that their appearance is related to the 
occurrence of the mesodermal somites. 
Up to the end of the third month the cord is practically as long as the 
spinal canal, but later the canal grows in length more rapidly than the cord, so 
that the latter becomes relatively shorter, though actually it elongates. As a 
result of this unequal growth, the nerves which pass out between the lower 
vertebrae must lengthen, and so the bunch of nerves termed the cauda equina is 
formed. The motor nerves arise from cells situated in the ventral horn of the 
cord, and grow out toward the muscles for which they are destined; the sensory 
nerves, however, arise from a series of thickenings situated just external to the 
lips of the medullary groove, which, on the closure of the groove, separate from 
the ectoderm and sink down into the mesoderm. From each cell of these thick- 
enings, which are the dorsal root-ganglia, two processes are sent off, one of 
which penetrates the substance of the cord, while the other extends peripherally. 
There is thus a fundamental distinction between the motor and the sensory nerve- 
fibres, the former always growing out from the central system, while the latter 
arise externally to the cord and brain, and grow inward toward them. 
In the anterior portion of the medullary canal, from which the brain develops, 
neuromeres are present as in the cord ; but, 
in addition, two more distinctly marked con- 
strictions appear and divide the brain into 
three primary vesicles. The roof-plate of 
the most posterior vesicle forms a thin roof 
to the cavity of the vesicle (Fig. 122), which 
broadens out to form the fourth ventricle, a 
transverse thickening, however, developing 
in the more anterior part of the roof, and 
later enlarging to form the cerebellum. In 
the posterior part of the vesicle the dorsal 
and ventral zones become well developed, 
forming the medulla oblongata, while ante- 
riorly fibres grow downward on each side 
from the cerebellum toward the ventral 
mid-line, forming the jpons. In consequence, 
it is customary to regard the third vesicle as 
being secondarily divided into two vesicles, 
the posterior of which is termed the after- 
brain, or metencephalon (myelencephalon), 
while the anterior, which includes the cere- 
bellum and pons, is known as the hind- 
brain, or epencephalon. 
The cavity of the middle vesicle does 
not increase in size as rapidly as the others, 
but assumes the form of a canal, and is 
termed the iter or aqueduct. The roof-plate 
retains its primitive slight development, the 
dorsal zones, however, giving rise to four well-marked thickenings, the corpora 
Fig. 122.—Diagram of the brain at an early 
stage of development: I, cavity of primary pros- 
encephalon ; 11, cavity of mesencephalon; 111, 
cavity of epencephalon ; AU, auditory pit; CO, 
central canal of spinal cord; CE, cerebellum; 
CR, crura cerebri and quadrigemina; CV, cere- 
bral vesicle; FO, foramen of Monro; MO, me- 
dulla oblongata; OL, olfactory lobe; OPT. V., 
optic vesicle; SP, spinal cord; Til, thalamus 
opticus. (Martin.) THE NERVOUS SYSTEM. 
105 
quadrigemina, while the ventral zones become modified to form the crura cerebri. 
To this differentiated middle vesicle is given the name of the mid-brain, or mesen- 
cephalon (Fig. 123). 
The anterior vesicle under- 
goes greater changes than either 
of the others. First, from the 
lower part of its lateral walls 
two pouches grow out, finally 
come into contact with the ecto- 
derm of the sides of the head, 
and form the optic vesicle (Fig. 
122), and later a constriction of 
the original wall of the vesicle 
appears, the vesicle thus becom- 
ing divided into two portions, the 
anterior of which, growing most rapidly on each side of the median line, eventu- 
ally gives rise to the cerebral hemispheres, which are together termed the fore- 
brain, or prosencephalon, while the median portion, together with the entire 
posterior portion of the original vesicle, forms the ’tween-brain, or thalamen- 
cephalon, which contains the third ventricle. 
The anterior wall of the third ventricle is evidently, since the hemispheres are 
lateral outgrowths, the front wall of the primitive brain, and it constitutes the 
lamina terminalis of the adult. The greater portion of the roof of the third 
ventricle becomes reduced to a thin layer of cells, which, together with the pia, 
which lies immediately above it, forms the velum interpositum, while more poste- 
riorly an evagination of the roof produces a stalk surmounted by a solid oval 
body, the epiphysis, or pineal body, which comparative anatomy shows to be the 
rudiment of an unpaired, median eye. In the floor of the ventricle there is to 
be found, in addition to the optic stalks, a hollow, funnel-like downgrowth, the 
infundibulum, which ends in a solid body, the hypophysis, or pituitary body, 
formed partly by a dilatation of the extremity of the infundibulum, and partly 
by a mass of tissue which arises as an upgrowth from the roof of the mouth, from 
which it becomes separated; and lastly, in each of the lateral walls of the ven- 
tricle there is to be found an oval thickening, the optic thalamus (Fig. 122), 
developed from the dorsal zone, the subthalamic tissues being the product of 
the ventral zones. 
mesencephalon 
CHOROID 
PLEXUS- 
FORAMEN 
OF MONRO- 
CAUDATE- 
NUCLEUS 
■CEREBELLUM 
FOURTH 
VENTRICLE 
-OBLONGATA 
Fig. 123.—Brain of embryo, side view. (Mihalcovics.) 
Since the cerebral hemispheres develop as lateral enlargements of the anterior 
of the two secondary portions of the vesicle, and since this portion contains a 
cavity (a part of the third ventricle), it is clear that each hemisphere will contain 
a lateral prolongation of this cavity, a lateral ventricle, and that each lateral ven- 
tricle will communicate with the sides of the anterior end of the third ventricle, 
this communication being the foramen of Monro. The hemispheres are, strictly 
speaking, excessive developments of the dorsal zones of the anterior vesicle, and 
there occurs in the wall of each of them a thickening, termed the corpus striatum, 
which is continuous behind with the optic thalamus. As the hemispheres continue 
to develop they project in front of the lamina terminalis and overlap behind the 
roof and sides of the ’tween- and mid-brains ; and the lateral ventricles, increas- 
ing in size pari passu with the growth of the hemispheres, become prolonged into 
anterior, posterior, and lateral horns. Into the outer layers of the hemispheres 
an immigration of cells occurs, the cerebral cortex being thus formed, and during 
the earlier months of development division of these cells occurs with considerable 
rapidity, gradually becoming rarer, however, until some time before birth, when 
it completely ceases, there being, in all probability, no normal increase in the 
number of cells forming the cerebral cortex after birth. 
At about the fourth week of development a finger-like dilatation forms on 
the anterior part of the under surface of each cerebral hemisphere, a prolongation 
trom the lateral ventricle of the same side passing into it. Anteriorly, the dila- 106 
EMBRYOLOGY. 
tations fuse with the olfactory ganglia, to which the olfactory nerves pass from 
the mucous membrane of the nasal cavity, and they form the olfactory lobes, or 
rhinencephalon, the cavities which they contain becoming obliterated before adult 
life is attained. 
Up to the fifth month of development the surface of the hemispheres is 
smooth, but at this time a depression appears at the side of each hemisphere 
(Fig. 124) involving that portion of the cortex which lies immediately external 
to the corpus striatum ; this is the 
Sylvian depression. Later the lips 
of the depression grow toward each 
other, the upper one growing more 
rapidly and forming a distinct fold, 
the operculum, which covers in the 
floor of the depression. This covered 
portion of the cortex is the insula of 
descriptive anatomy, the fissure be- 
tween the edge of the operculum and 
the lower lip of the depression being 
the Sylvian fissure. In the subse- 
quent months of development addi- 
tional fissures appear, some of which 
are of sufficient depth to form eleva- 
tions projecting into the cavities of 
the lateral ventricles, the hippocampus of the middle horn and the calcar of the 
posterior horn being formed in this manner. 
The lamina terminalis, as has been seen, forms the front wall of the third 
ventricle, and accordingly connects the two cerebral hemispheres in front. Its 
lower part remains relatively thin, but above it becomes much thickened from 
before backward, the thickening having a triangular shape. In the thickening a 
slit-like cavity appears, and through that portion of the thickening which forms 
the roof of the cavity nerve-fibres pass across from the cortex of each cerebral 
hemisphere to that of the other, forming the corpus callosum, while in the floor 
of the cavity longitudinal fibres develop, forming the pillars of the fornix. The 
cavity itself is the so-called fifth ventricle, its lateral walls being the septum luci- 
dum, and it is evident from its mode of development that it cannot be considered 
homologous with the other ventricles of the brain. 
One other set of structures require notice here, though they are not actual 
constituents of the central nervous system. These are the choroid plexuses, 
which consist of collections of blood-vessels developed in the pia over certain 
portions of the brain where the walls are exceedingly thin—as, for instance, over 
the roof of the third and fourth ventricles and along the floor of the lateral ven- 
tricles. The vessels push these thin membranes in front of them into the interior 
of the brain, and thus come to lie apparently in the interior of the ventricles, 
though in reality they are separated from them by the prolongation of the roof 
or floor which they carry in front of them. 
The Sympathetic System.—The sympathetic ganglia have usually been regarded 
as formed by a proliferation of cells from the anlagen of the dorsal root-ganglia, 
and as being, therefore, of ectodermal origin. More recent observations tend to 
assign them to the mesenchyme, their first indication being found in a cord of 
cells in the mesenchyme just external to the dorsal aorta. The history of the 
system needs further study, however, before definite statements can be made 
concerning it. 
CEREBELLUM 
OLFACTORY 
LOBE. 
Nons. 
Fig. 124.—Brain of six-months’ human embryo, natural 
size. (Kolliker.) 
The Olfactory, Gustatory, and Tactile Organs.—Of the organs of special sense 
the tactile and gustatory are not as yet thoroughly understood embryologically. 
The olfactory organ appears as two circular thickenings of the ectoderm, one on 
each side of the fronto-nasal process, just in front of the mouth, and these, sinking 
beneath the surface, come to form the floor of a pair of depressions (Fig. 99) THE EYE. 
107 
whose lips, gradually approaching, finally fuse, except below, to form a pair of cavi- 
ties, the openings into which are the anterior naves. These at first communicate 
with the mouth, but become separated from it by the union of the two maxillary 
processes, a separation further perfected by the formation of the hard palate. 
The Eye.—The first indications of the eye are a pair of hollow outgrowths 
from the anterior vesicle of the brain (Fig. 122), and these take the form of 
vesicles in contact with the ectoderm externally and united to the Tween-brain 
by narrow optic stalks. That portion of the wall of each vesicle which is in 
contact with the ectoderm becomes invaginated, and the vesicle thus becomes 
converted into a double-walled cup, from whose walls the retina is formed. The 
invagination proceeds more rapidly on the under side of the vesicle, and is con- 
tinued backward some distance on the optic stalk, which thus becomes grooved on 
its under surface, the optic cup being imperfect along a narrow line on its under 
surface, this opening being the choroidal fissure (Fig. 125). When the retina is estab- 
Fig. 125.—Diagrams of the formation of the optic cup and choroidal fissure. 
lished nerve-fibres grow from its cells toward the brain, choosing the optic stalk 
as the path of least resistance, and thus converting it into the solid optic nerve. 
That portion of the surface ectoderm with which the optic vesicle came in 
contact early begins to thicken, and later becomes invag- 
inated, pressing upon the wall of the vesicle. This ecto- 
derm gradually separates from the surface and forms a 
spherical, hollow structure, lying in the mouth of the optic 
cup; it is the anlage of the lens (Fig. 126). Later, the cells 
of its anterior wall flatten down to form the epithelium 
of the lens (Fig. 127), while those of the posterior wall 
become much elongated, and are converted into fibres 
running in various directions and completely filling the 
original cavity. At first the lens is in close contact 
with the surface ectoderm; but later mesenchymal 
tissue pushes in between it and the ectoderm, forming 
a layer which becomes converted into the cornea (Fig. 
127), the ectoderm external to it forming the conjunc- 
tiva. At the same time a concentration of mesenchyme 
takes place all around the optic cup to form the sclerotic 
and choroid coats of the eyeball, and between the outer 
surface of the lens and the cornea fluid collects, forming 
the aqueous humor. The vitreous body is formed by the 
migration of mesenchyme into the interior of the optic 
cup through the choroid fissure, and is at first richly 
supplied with blood, the artery bringing it running 
along the groove on the under surface of the optic 
stalk, and so entering the choroid fissure. In the later 
Fig. 126.— Semi-diagram of 
the secondary optic vesicle and 
the developing lens : AB, layer 
which becomes pigmentary reti- 
nal layer; C, posterior chamber, 
to be occupied by vitreous; B, 
remnant of cavity of primary 
optic vesicle; 18, layer which 
becomes greater part of retina; 
L, lens, as a cup open on exte- 
rior ; M, M, M, mesoderm; M , 
M'. points from which meso- 
derm grows in to form ins and 
body of cornea; -f, place at 
which the primary optic vesicle 
has been doubled back on itseli ; 
*, point of invagination of ecto- 
derm to form lens. (Wieder- 
sheim.) 108 
EMBRYOLOGY. 
development the choroid fissure closes completely, and the lips of the groove on 
the stalk also meet and close, the artery thus becoming enclosed by the stalk, and 
forming the arteria centralis retinae of the adult. Later on, the mesenchyme in 
CONNECTIVE-TISSUE ENVE 
LOPE OF OPTIC CUP 
SMALL WING 
OF SPHENOID- 
RECTUS SUPERIOR- 
CENTRAL ARTERY 
OF RETINA ” 
-UPPER LID 
OPTIC NERV 
-LENS 
RETINAL PART_ 
OF OPTIC CUP 
CRYSTALLINE 
EPITHELIUM 
VITREOUS 
BODY 
-CORNEA 
PUPILLARY 
MEMBRANE 
RECTUS 
INFERIOR” 
PIGMENT LAYER 
OF RETINA 
LOWER LID 
Rudiment of iris 
iRSGM ENT OF IRIS 
Fig. 127.—Horizontal section of the developing eye. (After Kolliker.) 
CILIARY PART 
OF OPTIC CUP 
the interior of the optic cup becomes converted into the peculiar gelatinous 
tissue of which the vitreous is composed, and its blood-supply becomes cut off, 
the only trace of the existence of the artery in front of the retina being the space 
originally occupied by the artery, persisting as a canal traversing the centre of 
the vitreous, and known as the hyaloid canal. When the blood-supply of the 
vitreous is at its highest development it extends as far forward as the lens, which 
it surrounds with a vascular capsule, which later normally disappears completely. 
Of the structures accessory to the eye, the eyelids develop as folds of skin, 
which grow together over the eye, and remain fused together until shortly before 
birth. The lachrymal (/lands are formed as solid ingrowths (later becoming hol- 
low) from the conjunctiva, just at the point where the upper-eyelid folds arise, 
while the lachrymal duct is developed as a thickening of the ectoderm, which 
forms the floor of the groove found at an early stage between the fronto-nasal 
and the maxillary processes. This thickening later becomes hollowed out, and 
the lips of the groove meet over the canal so formed, completely enclosing it, 
and, as the nasal cavity differentiates, the lower end of the duct comes to commu- 
nicate with it. 
The Auditory Organ.—The membranous labyrinth or inner ear is the first por- 
tion of the auditory organ to develop, appearing as a circular depression of the 
ectoderm over the first visceral cleft (Fig. 122). This auditory pit deepens, 
sinking down into the subjacent mesenchyme, its floor at the same time thicken- 
ing, and it eventually becomes constricted off from the ectoderm as a completely 
closed sac, a small process from one side of this representing the remains of its 
connection with the surface, and forming the ductus endolymphaticus. From the 
ventral wall of the sac a tubular outgrowth forms, which is the anlage of the 
cochlea, and in the angle between this and the sac proper is to be found the 
auditory ganglion, which had previously formed as a thickening of the ectoderm THE AUDITORY ORGAN. 
109 
near the auditory pit, and had migrated into the subjacent mesenchyme. A con- 
striction now begins to form in the inner wall of the sac (Fig, 129), dividing it into an 
upper and a lower portion ; and from 
the upper portion two flat hollow disc- 
like outgrowths develop, one of which 
lies in a horizontal plane, while the 
other is directed vertically, but is bent 
so that the anterior half of it lies al- 
most at right angles with the posterior. 
These are the anlagen of the semicir- 
cular canals (Fig. 130), which are finally 
formed from the edges of the discs, the 
central portion of the horizontal disc and 
of each half of the vertical one disap- 
pearing, so that three canals are formed, 
each opening at both extremities into 
the upper portion of the auditory sac. 
At one end of each canal a widening 
occurs, and, from the mode of devel- 
opment just outlined, it will be seen that the two vertical canals will be united 
together at one end to form a common canal before opening into the sac (Fig. 131). 
The constriction of the wall of the sac deepens gradually, until finally the upper 
portion, or utriculus, communicates with the lower portion, or sacculus, only by a 
slender canal, which represents that portion of the original sac with which the 
ductus endolymphaticus communicates. While these processes have been going 
on, a second constriction has formed between the cochlear anlage and the sacculus, 
whereby the connection of these two parts is also reduced to a slender canal, the 
canalis reuniens. In correspondence with this division of the original sac a 
division of the auditory ganglion also occurs, one portion of it, the vestibular 
WALL OF 
AFTER-BRAIN 
RECESSUS 
■labyrinthi 
.VESICLE OF 
LABYRINTH 
GANGLION 
'COCHLEARE 
-COCHLEAR PORTION 
OF LABYRINTH 
Fig. 128.—Section through the auditory vesicle of 
a sheep embryo. (Hertwig, after Boettcher.) 
■AFTER-BRAIN 
auditory NERVE 
VERTICAL SEMI- 
CIRCULAR CANAL 
RECESSUS 
•LABYRINTHI 
vertical semi- 
■CIRCULAR CANAL 
FURROW BETWEEN 
GANGLION 
cochleare' 
UTRICULAR AND 
SACCULAR PORTIONS 
OF LABYRINTH 
GANGLION 
COCHLEA 
COCHLEARE 
COCHLEA 
Fig. 129.—Section through the auditory vesicle of sheep embryo, somewhat older than that in Fig. 
(Hertwig, after Boettcher.) 
ganglion, being in relation to the sensory epithelium of the utriculus, sacculus, 
and semicircular canals, while the other is drawn out into an elongated band, the 
spiral or cochlear ganglion, which follows the coils into which the cochlea becomes 
thrown, and stands in relation to the organ of Corti, which develops from the 
cochlear epithelium. 
In the mean time, a condensation of the mesenchyme surrounding each audi- 110 
EMBRYOLOGY. 
Tory sac has been taking place, and the portions of the tissue immediately in 
contact with the walls of the sac become converted into fibrous connective tissue, 
and so strengthen the walls of the mem- 
branous ear, while the outermost portions 
become converted into cartilage, and later 
into bone-, forming the periotic capsule, 
in whose walls, however, three membra- 
nous areas are left, one of these being 
where a canal, the ductus perilymphati- 
cus, leads from the perilymphatic space 
to the surface of the bone. Between the 
inner wall of the capsule (which is com- 
posed of dense bone, and forms what is 
termed the osseous labyrinth) and the 
connective tissue a layer of the mesen- 
chyme is left in the form of a loose 
connective tissue, which subsequently 
degenerates, leaving a space, which be- 
comes filled with fluid, around the mem- 
branous ear. This is the perilymphatic 
space, which, in the cochlea, is separated into two parts by the membranous 
cochlea, being attached on either side to its wall, so that a section of any coil 
of the cochlea will show the membranous cochlea, known in anatomy as the scala 
media, with a perilymphatic space above it, the scala vestibuli, and another below 
it, the scala tympani, these two spaces communicating, however, at the apex of 
the cochlea. 
DUCTUS 
ENDOLYM- 
PHATICUS, 
ANT, VERTICAL 
SEMICIR. CANAL. 
POST. VERTICAL 
'SEMICIR. CANAL. 
HORIZONTAL 
SEMICIR. CANAL. 
UTRICULUS. 
SACCULUS. 
COCHLEA. 
Fig. 130.—Model of internal ear of human em- 
bryo of about five weeks. (C. S. Minot, after W. 
His, Jr.) 
The middle ear is the remains of the first visceral cleft, the groove on the 
wall of the pharynx which represents the cleft becoming converted into a canal 
ANT. VERTICAL 
''■'s.SEMICIR. CANAL. 
DUCTUS 
ENDOLYM-. 
PHATICUS. 
SEMICIR. CANAL. 
UTRICULUS, 
I POST. VERTICAL 
jSEMICIR. CANAL. 
SACCULUS. 
COCH LEA. 
CANALIS REUNIENS. 
Fig. 131.—Model of internal ear of human embryo of about two months. (C. S. Minot, after W. His, Jr.) 
by the fusion of its lips, the upper end of this canal being enlarged to form a 
cavity, the tympanic cavity, while the rest of it forms the Eustachian caned, which 
opens below into the pharynx. The tympanic cavity is, however, up to birth 
exceedingly narrow, practically merely a slit, its walls, beneath the mucous mem- 
brane lining it, being largely composed of a loose gelatinous tissue, in which lie 
imbedded three small bones, the malleus, stapes, and incus. The upper end of 
MeckeFs cartilage, which develops, as has been seen, in the first branchial arch, 
separates from the lower portion, and forms two small bones, which are imbedded 
in the front wall of the tympanum, and are the malleus and incus ; while the 
stapes seems to be produced by the fusion of two distinct parts. Its flat portion, THE AUDITOBY ORGAN. 
which rests in one of the three nnossified spots of the osseous capsule of the inter- 
nal ear, the foramen ovale, seems to be really the portion of the wall of the cap- 
sule which should till this foramen, the mesenchyme immediately around it having 
remained membranous, while its arch is the ossified upper end of the cartilage 
of the second branchial arch. These bones are at first imbedded in the gelatinous 
tissue of the wall of the tympanic cavity. After birth, air is taken into this cavity 
through the Eustachian tube, and the cavity enlarges, pressing aside the gelati- 
nous tissue and surrounding bones, which thus form a chain extending from the 
tympanic membrane to the foramen ovale, and apparently passing through the 
middle of the tympanic cavity, though in reality they are enclosed by the mucous 
membrane which lines the cavity. 
Two of the three unossified spaces in the wall of the osseous capsule of the 
inner ear have been accounted for in the ductus perilymphaticus and the foramen 
ovale ; the third opening is the foramen rotundum, which is closed by a membrane 
on which the scala tympani abuts. The outer wall of the tympanic cavity is 
formed by the tympanic membrane, and is at first thick with the gelatinous tissue 
which encloses the auditory ossicles, it being only after birth that it is reduced to 
the thin membrane found in the adult. It is formed partly by the partition 
between the external and internal grooves of the first branchial cleft, and partly 
by the upper ends of the first and second branchial arches. 
Just as the inner groove of the first branchial cleft forms the Eustachian tube 
and tympanum, so the upper end of the outer groove of the same cleft forms the 
outer ear, the pinna developing from elevations appearing on the first and second 
visceral arches in the vicinity of the persistent part of the groove. THE BONES. 
GEORGE WOOLSEY. 
THE adult human skeleton consists of a number1 of hones, with a small amount 
of cartilage in some parts, where they are joined or articulated with one 
another. The bones, as they are generally studied after maceration and drying, 
are composed of mineral or earthy salts, principally phosphate and carbonate of 
lime.2 The soft organic parts, of which a prepared bone is deprived, consist 
partly of the fibrous and vascular periosteum, which covers 
the surface and is continuous with the connecting liga- 
ments, and the medulla or marrow, which fills the internal 
cavities. 
The main functions of bones are to afford a solid frame- 
work, to support softer parts, to protect delicate organs 
and to serve for the attachment and leverage of muscles 
which produce the different movements. To serve these 
different purposes bones must differ in their outward form 
according to which we distinguish—(3) Long bones, con- 
sisting of a shaft or diaphysis and two expanded extremi- 
ties or epiphyses, as in the limbs. They afford support 
and leverage for motion, and are usually somewhat curved 
in one or two directions, thus securing greater strength 
and elasticity ; (2) Flat hones, as in the pelvis, scapula, 
and the roof of the skull, affording protection and support 
to the contained parts, and also muscular attachment; (3) 
Short hones, as in the wrist and ankle, where strength com- 
bined with free motion is required; (4) Irregular or 
mixed, hones, like the vertebrae and many of the bones 
of the skull. 
Internal Arrangement.—On longitudinal section of a 
long bone (Fig. 132) notice that there is an outer layer of 
hard, compact substance, varying in thickness and enclosing 
a central or medullary cavity, in the shaft of the bone, and 
porous, spongy or cancellous bony tissue at the extremities. 
In the recent state the medullary cavity is filled with yel- 
low or fatty marrow, and the cavities of the cancellous 
tissue with red marrow. Short, flat, and irregular bones 
have an outer layer of compact substance, enclosing can- 
cellous tissue containing red marrow. The cancellous 
tissue at the ends of long bones and in other bones bearing 
pressure is so arranged that its bony lamella; are principally 
directed in the lines of pressure or of muscular tension. 
The porosity or hollowness of bones serves to combine 
requisite size and strength with lightness. 
Development of Bones.—In the early embryo the bones are preformed either 
Fig. 132.-—The longitudi- 
nal section of a long bone. 
1 Exclusive of the ossicles of the ears, the teeth, and the Wormian bones, there are 200 bones, of 
which 64 are in the upper extremity, 62 in the lower, and 74 in the trunk, distributed as follows: the 
vertebral column 26, the skull 22, the ribs and sternum 25, and the hyoid bone 1. 
2 Respectively 51 per cent, and 11 per cent, of the solids of fresh bone. 114 
THE BONES. 
in membrane or, in the majority of cases, in cartilage covered by membrane, so 
that all are possessed of membranes, and ossification beneath membrane is found 
in all, and exclusively in some.1 One or more original or 'primary centres appear 
for each bone, from which ossification proceeds, forming the diaphysis (“ between- 
growth ”) or body. After a varying time one or several secondary or tertiary 
centres may appear, which form the epiphyses (“ upon-growth ”), united to the dia- 
physis for some time by cartilage. Some of these form the extremities of long 
bones, others projecting processes like the acromion of the scapula or the tro- 
chanters of the femur.2 
Bone formed in cartilage is not adapted to be permanent, for the cartilage 
is non-vascular, and, further, it is not true bone, but a mere calcification. It is 
therefore resorbed and replaced by vascular bone from an ossific centre beneath 
the membrane. 
In the long bones the first or primary centre in the shaft appears before birth.3 
Later, one or more secondary centres appear at either end, all but three4 after 
birth. The bone-centres in the shaft and extremities of long bones are separated 
from one another by a layer of cartilage (epiphyseal cartilage), which continues to 
grow at the same time that the bone-centres on either side grow into it. By this 
means the bone is enabled to grow in length until first one, and, when growth is 
completed, finally both, cartilages cease to grow, and the shaft and extremities 
unite by ossification of the intervening layer of cartilage. Such bones grow 
in diameter by the deposit of bone beneath the periosteum. Bones in which 
ossification is begun and completed in membrane, as in the vault of the 
skull, are enabled to increase in size by the growth of the membrane in the 
sutures separating them, until they have attained their full size, when this 
growth stops. 
Until the epiphyseal cartilage has ossified separation without bony fracture 
may occur here. The date of this ossification is therefore of importance in some 
cases. The bony union of shaft and extremities takes place according to the fol- 
lowing rules : 
1. The extremity whose ossific centre is the first to appear is the last to unite 
with the shaft. Exception : the lower end of the fibula, but the upper end is 
vestigial. 
2. The extremity toward which runs the nutrient artery is the first to 
unite. 
3. The nutrient arteries run toward the elbow and away from the knee— 
i. e., down hill—if elbow and knee both be flexed. 
4. Union of the epiphyses and diaphyses of long bones occurs from the six- 
teenth to the twenty-second year (occasionally twenty-fifth year, tibia), and 
earlier in the upper than in the lower extremity. 
5. When two or more centres of ossification occur in an epiphysis, these unite 
together before the epiphysis unites with the diaphysis or shaft. 
Many bones of the skull are composite, or made up of two or more elements, 
separate in their embryonic development, in young bones, and in the skulls of 
other vertebrates. 
The study of these details and the comparison of the human anatomy with 
that of other vertebrates, on the basis of their development, constitute the study 
of morphology, in which the most recent and interesting advances in anatomy 
have been made. 
Descriptions of Bones.—The student of osteology should always have the actual 
bones in his hand as he follows their descriptions, remembering that the latter 
represent the average of bones, and that it is very rare to meet with a bone in 
which every detail corresponds to the description. 
1 Ossification commencing in membrane may invade and replace cartilage, as in the clavicle. 
2 Prominent projections not developed from independent centres are called apophyses. 
3 Many primary centres of ossification appear after birth, as in the carpal bones. 
4 The adjoining ends of the femur and tibia, and sometimes the head of the humerus. THE SPIN E. 
115 
The surface of young bones is comparatively smooth. The rough lines and 
ridges on adult bones are due to ossification at the attachment of muscles. Any 
marked bony prominence may be called a process or apophysis (“ out-growth ”); 
if blunt, a tuberosity when large, a tubercle when small; if sharp, a spine or 
spinous process; if long, a line or ridge, when narrow, a crest, when broader; if 
articular, a condyle (“ knuckle ”), or a head when supported on a constricted part 
or neck. A depression or hollow space in or upon a bone or between several 
bones is sometimes called a fossa (“ ditch ”). A glenoid (“ cavity-like ”) fossa 
refers to a shallow articular depression, a cotyloid (“ cup-like ”) fossa to a deeper one. 
Sinus and antrum are terms applied to cavities within certain bones. A fissure is 
a narrow slit; a foramen a short opening ; a canal or meatus, a longer, tube-like 
passage-way. Other terms used require no explanation. 
In describing the different aspects of a bone or other anatomical part the 
body is supposed to be in the erect position. A surface, extremity, or other part 
directed toward the head is called superior; toward the feet, inferior ; toward the 
front, ventral or anterior; toward the back, dorsal or posterior. That aspect 
directed toward the median, vertical, antero-posterior plane of the body is called 
internal or mesial; that away from the same plane, external or lateral. 
THE SPINE. 
The spine, or vertebral column, is composed of 26 superimposed bones called 
vertebrae (“ capable of turning ”). The name spine is derived from the series of 
spines or spinous processes which are the most obvious portions of the column of 
bones in the undissected body. Of these the upper 24 are true or movable vertebrae, 
and are divided from above downward into 7 cervical, 12 thoracic, and 5 lumbar. 
Of the two lower composite bones comprising the false vertebrae, the upper one, or 
sacrum, is formed by the fusion of 5 vertebrae, and the lower one, or coccyx, of 4 
ankylosed, vestigial, terminal vertebrae, all separate in early life. 
A typical vertebra consists of a body or centrum in front, with a neural arch 
behind, which completes the vertebral foramen, in the series of which the spinal 
cord and its membranes are lodged and protected. 
The disc-like body supports and bears the weight of the head and trunk. Its 
superior and inferior surfaces are flattened or slightly concave, and rough for the 
connecting intervertebral discs. The circumference is concave vertically, convex 
horizontally, but behind it is concave in both directions, where it bounds the 
foramen and presents large foramina for veins.^ 
The neural arch is formed of two symmetrical halves, and consists of two 
pedicles and two laminae, supporting seven processes—four articular, two trans- 
verse, and one spinous. 
The pedicles (“little feet”), or ventral parts of the arch, consist of two nar- 
row, thick piers of bone, projecting horizontally back from the upper part of the 
dorsal and external aspect of the body. Above and below the pedicles are the 
vertebral notches, which, with notches of adjacent vertebrae, form the intervertebral 
foramina for the passage of the spinal nerves and vessels. 
The laminae, broad and flat, complete the arch by fusing together in the median 
line behind. Their upper borders and lower anterior parts are rough for the 
attachment of the ligamenta subflava. 
The spinous process projects backward in the median line from the junction 
of the laminae, and serves for the attachment of muscles and ligaments. 
The transverse processes project outward from the junction of the pedicles and 
laminae on each side. 
The articular processes present an upper and a lower pair, extending upward 
and downward from the roots of the transverse processes, for articulation with 
the pairs above and below. The articular surfaces of the upper and lower pairs 
look in the opposite direction. 116 
THE BONES. 
THE CERVICAL GROUP. 
The typical cervical vertebrae (from the third to the sixth, inclusive) (Fig. 133) 
are especially characterized by the foramina in the transverse processes. The 
centrum, or body, is small, oval, and 
transversely elongated. Its upper sur- 
face is concave transversely, due to the 
elevation of its lateral margins into 
lips which articulate with the rounded 
lateral margins of the lower surface of 
the vertebra above. The lower ventral 
margin projects downward, so as to 
overlap the rounded ventral margin of 
the upper surface of the vertebra below. 
The depth of the body is equal in front 
and behind. The pedicles are directed 
obliquely outward and backward from 
about midway between the upper and lower borders of the body. The laminae 
are long, narrow, and more or less flattened from above downward. The spinous 
process is short, bifid at the extremity, and nearly horizontal. The transverse 
processes, directed outward and forward, are seen to be rather short, and their 
bifid extremities present ventral and dorsal tubercles. Its base is perforated by 
the costo-transverse foramen, which transmits the vertebral artery and vein in 
the upper six vertebra, and which divides the base into two roots. The dorsal 
root springs from the junction of the pedicles and lamina, like the thoracic trans- 
verse processes; the ventral root springs from the side of the body, correspond- 
ing in position to the vertebral end of a rib. It is a vestigial rib (costa), and is 
called the costal process. The superior articular processes look upward and some- 
what backward, the inferior downward and somewhat forward. The foramen is 
triangular, and larger than in the other regions. 
COSTO-TRANS- 
VERSE FORAMEN. 
-COSTAL PROCESS. 
TRANSVERSE 
PROCESS. 
iipii 
SPINAL 
FORAMEN. 
Fig. 133.—Cervical vertebra, viewed from above 
(Testut.) 
Peculiar Cervical Vertebrae.— 
These are the first, second, and 
seventh. The peculiarities of the 
first and second are such as to 
allow the freest movement of the 
head on the spinal column which 
is consistent with the safety of 
the spinal cord. 
The atlas or first cervical 
vertebra (Fig. 134) lacks a body 
and spinous process, and forms 
a ring consisting of two arches, 
ventral and dorsal, connecting 
two lateral masses. The body has become separated from the atlas and ankylosed 
to the axis as the odontoid process. The ventral arch, one-fifth of the ring, pre- 
sents in the median line in front a small tubercle for muscular and ligamentous 
attachment, and behind a round facet for articulation with the odontoid process. 
The dorsal arch, two-fifths of the ring, has a median tubercle behind, the rudi- 
ment of a spinous process, which, if present, would interfere with the rotation 
between the atlas and axis. On its upper surface, at the junction with the lateral 
mass, is a deep groove, sometimes a foramen, for the passage of the vertebral 
artery and the first spinal nerve. The groove or notch on the under surface, for 
the second spinal nerve, is also behind the articular process, while the lower nerves 
pass out in front of the articular processes. The lateral masses present above two 
oval, elongated, articular surfaces looking upward and inward, and diverging 
behind. These articulate with the condyles of the occipital bone and permit the 
nodding movements of the head. Transverse grooves may divide these surfaces 
COSTO-TRANS- 
VERSE FORAMEN. 
VENTRAL 
ARCH. 
TRANSVERSE/ 
PROCESS. ' 
SPINAL 
FORAM EN. 
Fig. 134.—The atlas, viewed from above. (Testut.) THE THORACIC GROUP. 
117 
in two or give them a kidney-shaped outline. The inferior articular processes, 
or the facets on the under surface of the lateral masses, are nearly flat and circular, 
looking downward and slightly inward. Their articulation with the axis permits 
the rotatory movements of the head. On the inner surface of each lateral mass, 
between the two articular processes, is a tubercle for the transverse ligament, 
which divides the interior of the ring into a smaller ventral segment for the 
odontoid process and a larger dorsal segment, the spinal foramen, for the spinal 
cord. The transverse processes are long, serve for the leverage of the rotator 
muscles of the head, and are to be felt below the mastoid process of the temporal 
bone. The foramen in them is large, their costal processes are slender, and their 
extremities broad and not bifid. 
The axis or second vertebra (vertebra dentata, “ toothed vertebra”) (Figs. 135, 
136) has a large, strong body, surmounted by the odontoid (“tooth-like”) process, 
-ODONTOID PROCESS. 
ARTICULAR SURFACE 
FOR VENTRAL 
ARCH OF ATLAS. 
ODONTOID PROCESS. 
ARTICULAR FACET 
- FOR VENTRAL 
ARCH OF ATLAS. 
TRANSVERSE 
“ PROCESS. 
INFERIOR ARTICU- 
LAR PROCESS. 
SPINOUS PROCESS. 
TRANSVERSE 
PROCESS. 
Fig. 135.—The axis, front view. (Testut.) 
Fig. 136.—The axis, its right side. (Testut.) 
on which as a pivot the atlas rotates, carrying with it the head. This process has 
in front a smooth surface for articulation with the atlas, and behind, at a slightly 
lower level, a smooth groove, which forms a constriction, the neck, and receives 
the transverse ligament. The lower surface of the body is like that of the typical 
cervical vertebra, except that the overlapping lip is more prominent. In front 
the body presents a vertical median ridge and two lateral depressions. The 
pedicles are stout, and partly on them, partly on the body, rest the oval superior 
articular surfaces, close to the base of the odontoid process, and directed upward 
and slightly outward. The weight of the head is transmitted to these surfaces 
through the lateral masses of the atlas, and from them it passes largely to the 
body and less to the inferior articular processes of the axis through a strong arch, 
the piers of which are the body and inferior articular processes. From this 
point down the weight is borne mostly by the bodies. The inferior articular 
processes resemble those below in form, position, and direction. The spinous 
process is strong, deeply bifid, and grooved below. It attaches muscles which 
rotate the head. The transverse processes are short. The costal processes are 
thick at their bases, and the anterior tubercles are very rudimentary. The 
foramina for the vertebral arteries are directed obliquely upward and outward 
toward those in the atlas. 
The seventh cervical vertebra is called the vertebra, prominens, from the length 
of its spinous process, which is a landmark readily felt beneath the skin. This is 
not bifid, and it attaches the ligamentum nuchse. The costal processes and their 
anterior tubercles are small, but sometimes are larger and segmented off as cervical 
ribs. The costo-transverse foramen is small. The transverse processes are large. 
The spinous process of the sixth cervical vertebra is occasionally so long as to 
be mistaken for that of the seventh, and the anterior tubercle of its transverse 
process is called the carotid tubercle, as against it the carotid artery may be 
compressed. 
THE THORACIC GROUP. 
The thoracic vertebrae (Figs. 137—139) are typically characterized by the pres- 
ence of articular facets on the bodies and transverse processes, for articulation 
with the ribs which they support. The disc-like body, or centrum, is oval oi 118 
THE BONES. 
heart-shaped, only slightly wider transversely than from before backward, and 
deeper behind than in front. Where the body joins the arch two demi-facets are 
found on either side, one at the upper and one at the lower border. Each facet 
with the contiguous one on the adjacent vertebra completes a cavity for the head 
of a rib. The lower vertebral notches are deeper than the upper. Each broad, 
flat pair of the laminae is imbricated, or sloped, over the pair below, like the tiles 
BODY.' 
DEMIFACET FOR 
f SPINAL 
FORAMEN. 
HEAD OF RIB. 
PEDICLE. 
FACET FOR 
TUBERCLE OF RIB 
LAM INA. 
Fig. 137.—A thoracic vertebra, upper surface. (Testut.) 
of a roof. The spinous process is long and three-sided, and projects considerably 
downward, especially in the middle of the series. The transverse processes project 
outward and slightly backward. The oval facets on the front of their tips are for 
articulation with the tubercles of the ribs. The rib in situ forms with this process 
a costo-transverse foramen. Of the two pairs of articular processes, the articular 
UPPER INTERVER- SUPERIOR ARTICU 
FACET FOR 
TUBERCLE OF RIB. 
Fig. 138.—Thoracic vertebra, seen from the left side 
(Testut.) 
Fig. 139.—Thoracic vertebra, viewed from 
behind. (Testut.) 
surfaces of the upper pair look backward and slightly outward and upward, 
those of the lower pair forward and slightly inward and downward. The foramen 
is round, and not as large as in the cervical or lumbar region. 
Peculiar Thoracic Vertebrae.—These are the first, ninth, tenth, eleventh, and 
twelfth. 
The first is a transitional vertebra, resembling the lower cervical vertebrae, 
especially on its upper surface. The body is elongated transversely, and lipped 
laterally above. There are entire facets above for the first pair of ribs, and demi- 
facets below for the second pair. The superior articular processes have largely an 
upward direction. The spinous process is long, nearly horizontal, and even more 
prominent than that of the vertebra prominens. 
The ninth has demi-facets above, but frequently none below. If the lower 
ones are present, it is a typical vertebra. THE LUMBAR GROUP. 
119 
The tenth articulates with but one pair of ribs. It has no demi-facets below, 
and the upper facets are usually complete, and mainly on the pedicle. 
The eleventh has a complete facet on the base of each pedicle, and none on 
the short transverse processes. The large body is elongated transversely, and the 
spinous process is short, stout, and horizontal, thus approaching the lumbar type. 
The twelfth resembles the lumbar still more in its body, spinous and transverse 
processes. The latter are short, and present external, superior, and inferior 
tubercles, corresponding to the transverse, mammillary, and accessory processes of 
the lumbar vertebrae. The inferior articular processes look outward, as in the 
lumbar. As to facets, it resembles the eleventh. 
All the thoracic vertebrae are thus seen to have either entire or demi-facets 
above, and only the first eight or nine have demi-facets below. 
Variety.—The tenth vertebra occasionally has no facets on the transverse 
processes. 
THE LUMBAR GROUP. 
The five lumbar vertebrae (Fig. 140) are characterized by their large size and 
the absence of costal articular facets. The bodies are elongated transversely, and 
are slightly deeper in front than behind from the third down. The laminae are 
strong, short, and deep. The 
spinous processes are thick, hori- 
zontal, and broad from above 
downward. The slender so-called 
transverse processes project out- 
ward from the pedicles in serial 
line with the lower ribs. They 
are in reality costal processes, and 
sometimes are developed into lum- 
bar ribs, especially in the first 
lumbar vertebra. At their bases, 
dorsally, a small process is seen to 
project downward—the accessory 
tubercle or rudimentary transverse 
process. The facets of the superior 
articular processes are slightly con- 
cave, and look inward and some- 
what backward. From their outer 
edges a tubercle projects backward, 
the mammillary process, which corresponds to the superior tubercle of the lower 
thoracic vertebrae. The facets of the inferior articular processes look outward and 
slightly forward. They are nearer together, and are embraced by the superior 
processes, but not so closely as to prevent slight lateral and rotatory movements 
between the vertebrae. The foramen is triangular and larger than in the thoracic 
vertebrae. 
PEDICLE. 
MAM M I LLARY, 
TUBERCLE. 
ACCESSORY 
TUBERCLE. 
INFERIOR ARTICU 
LAR PROCESS. 
SUPERIOR ARTICU- 
LAR PROCESS 
SPINOUS PROCESS. 
Fig. 140.—Lumbar vertebra, viewed from above. (Testut.) 
The fifth lumbar vertebra is transitional, approximating the sacral. Its body 
is large, wedge-shaped, and much deeper in front than behind. To articulate 
with the first sacral vertebra its inferior articular processes are as wide apart as 
the superior. The transverse processes are large, broad, and conical, sometimes 
articulating with the sacral aim. The spinous process is short. 
Varieties.—ln a small percentage (estimated at 5 per cent.) of cases the fifth 
lumbar vertebra is so separated into two parts through the arch that the dorsal 
segment consists of laminse, spinous and inferior articular processes. 
Varieties as to the Number of Movable Vertebrce.—The cervical vertebrae are 
remarkably free from variation in number, not only in man, but in all mammals, 
with two or three exceptions. Variation in the number of thoracic and lumbar 
vertebrae raav be reciprocal when it depends upon an increase or decrease in the 
number of pairs of lower ribs, causing an increase in the thoracic and a decrease 120 
THE BONES. 
in the lumbar, or the reverse. Whether the extra vertebra be thoracic or lumbar, 
the characters of this vertebra are more those of the lumbar type. Or, again, 
the number of movable vertebrae may be increased or decreased by one, causing 
an increase or decrease of one in the thoracic or lumbar group. This increase is 
usually in the lumbar series, the lower one of which may be partly united to the 
sacrum. 
Cervical. 
Thoracic. 
Lumhar. 
Bodies: 
Small, transversely elon- 
gated. Sloped downward 
and forward. Lipped lat- 
erally. No costal facets. 
Heart-shaped. Deeper be- 
hind. Nearly equal 
transversely and antero- 
posteriorly. Costal facets. 
Large, elongated trans- 
versely. No costal facets. 
Pedicles: 
Pass outward and back- 
ward. Notches above 
and below nearly equal. 
Pass backward. Inferior 
notches deeper than supe- 
rior. 
Pass backward and slightly 
outward. Inferior notches 
deep. 
Laminae: 
Long, slender, flattened. 
Broad, short, imbricated. 
Short, deep, and thick. 
Spinous pro- 
Short, strong, bifid, and 
Long, projecting downward 
Quadrate, horizontal; of 
cesses: 
nearly horizontal. 
and overlapping. 
medium length. 
Transverse pro- 
Short, slender, directed 
Long, strong. Project out- 
Rudimentary, as ‘ ‘ acces- 
cesses; 
outward and forward. 
ward and backward. Ar- 
ticulate with tubercles of 
ribs. 
sory process.” 
Costal process: 
Slender, flat, ossified to the 
vertebra and transverse 
process. 
A separate bone (i. e. a 
rib). 
Ossified to vertebra. Flat, 
thin, “transverse pro- 
cess.’ ’ 
Superior articu- 
Flat. Directed upward and 
Mat. Directed backward 
Slightly concave. Directed 
lar processes: 
slightly backward. 
and slightly outward. 
inward and slightly back- 
ward. 
Slightly convex. Directed 
Inferior articu- 
Flat. Directed downward 
Flat, Directed forward and 
lar processes: 
and slightly forward. 
slightly inward. 
outward and slightly for- 
ward. 
Spinal foramen: 
Large, triangular, wide. 
Smaller, circular. 
Larger than in the thoracic. 
Triangular, wide. 
Table showing the Characters of the Typical Vertebrce of Each Group. 
The one distinguishing feature of a cervical vertebra is the costo-transverse 
foramen ; of a thoracic vertebra, the articular facet or demi-facet on the body; 
and of a lumbar, the absence of both of these peculiarities. 
THE SACRAL VERTEBRA!!. 
These in early life present the elements of five distinct vertebrae, but in the 
adult they are united into a curved triangular bone, the os sacrum, so called from 
its use in sacrifice (Figs. 141-143). It articulates laterally with the two hip- 
bones of the pelvic girdle, and, with the coccyx, completes the pelvis behind and 
above. In the erect position the sacrum lies obliquely, its upper surface or base 
inclined well forward. 
The sacral vertebrae decrease in size from above downward, thus giving a 
triangular shape, with a base, apex, ventral, dorsal, and lateral surfaces. Its 
separate elements present most, if not all, of the component parts of the movable 
vertebrae ; and the different parts of the sacrum are best understood Avhen studied 
with reference to these parts. 
The base of the sacrum, or the upper surface of the first sacral vertebra, 
resembles that of a lumbar vertebra. The large, transversely oval upper surface 
of the body extends forward to meet the ventral surface at the promontory of 
the sacrum which forms the dorsal boundary of the pelvic brim. Its superior 
articular processes, widely separated, look backward and inward like the lumbar, 
and have well-marked mammillary processes. The foramen is triangular. On 
the sides of the body we see the smooth alee, or wings, on the upper surface of 
the lateral masses, which are formed by the fusion of the transverse and costal 
processes on either side. The alse are continuous with the iliac fossae on each 
side. THE SACRAL VERTEBRA. 
121 
The apex of the sacrum, directed downward and a little forward, is formed by 
the transversely oval inferior surface of the body of the fifth sacral vertebra. 
This articulates with the coccyx by means of an intervertebral disc which in 
advanced life often ossifies. 
The ventral surface looks downward as well as forward. It is concave verti- 
cally, less so transversely. In the female it is broader, less curved vertically, 
Fig. I4l.—The sacrum, ventral view. (Testut.) 
and the apex is directed more obliquely backward. The five bodies form the 
middle of this surface. The upper two are large, the lower three smaller. 
They are separated by four transverse ridges, the ossified intervertebral discs, 
which are bounded laterally by the four pairs of ventral sacral foramina, the 
ventral openings of the intervertebral foramina. The ventral foramina transmit 
the ventral divisions of the first four pairs of sacral nerves, and lead externally 
into grooves in the lateral masses, which in front consist of fused costal processes. 
The dorsal surface is convex, rough, and narrower. It presents in the median 
line the spinous processes of the three or four upper vertebrae, united into one or 
two ridges by ossification of the connecting ligaments. The fifth spine always, 
the fourth usually, and all rarely, are wanting. On either side is the sacral 
groove, continuous with the vertebral groove above, and formed by the ankylosed 
laminae. The laminae of the fifth vertebra always, and those of the fourth often, 
are incomplete, leaving a triangular gap in the lower dorsal wall of the spinal 
canal. The lower margins of this gap are prolonged down as two tubercles, the 
sacral cornua (“ horns ”), which represent the inferior articular processes of the 
fifth sacral vertebra, and are connected by ligaments with the coccygeal cornua. 
On each side of the sacral groove is a series of small prominences, the artic- 
ular and mammillary processes, separated from a more external series of larger 
eminences, the transverse processes, by the four dorsal sacral foramina. The latter 
are opposite to, but smaller than the ventral sacral foramina. The four sacral 
intervertebral grooves on each side pass outward as canals as far as the lateral 
mass, where they bifurcate and pass forward and backward to the ventral and 
dorsal foramina. 
That part of the bone external to the foramina represents the lateral mass, 
whose lateral surfaces are broad and thick above, narrow below. The upper 
broad part of each lateral surface presents in front an uneven articular surface, 
called the auricular surface, from its ear-like shape, which articulates wit tie 
ilium, and behind a rough surface for the attachment of the posterior sacro-iliac 122 
THE BONES. 
ligaments. Below this the narrower rough margin attaches the sacro-sciatic liga 
THIRD DORSAL 
SACRAL FORAMEN 
INFERIOR LATERA 
ANGLE 
CORNU- 
Fig. 142.—The sacrum, dorsal view. (Testut.) 
merits, and ends in a projection, the inferior lateral angle, below which there is a 
notch, converted into a foramen by ligaments 
from the coccyx. Through this foramen passes 
the anterior division of the fifth sacral nerve. 
The sacral spinal canal curves and narrows 
with the bone. It is triangular above on trans- 
verse section, flattened or semilunar below, and 
lodges the lower end of the cauda equina and 
filum terminale with the spinal dura. 
Peculiarities and Varieties.—The second and 
third sacral vertebrae represent the sacrum of 
mammals—the fourth and fifth the first two 
caudal vertebrae, while the first represents the 
sixth lumbar of most quadrupeds. This explains 
the occasional partial or complete separation, and 
the transitional and partly lumbar character of 
the first sacral, not rarely present. The large 
number of sacral vertebrae in man is associated 
with his upright position. The sacrum some- 
times consists of six segments, more rarely of 
only four. In the former instance the first 
coccygeal is usually included. The breadth of 
the sacrum as compared with its length is re- 
markably great in man as compared with mammals, and especially so in the 
European specimens. 
CORNU. 
Fig. 143.—The sacrum, its right side. 
(Testut.) 
THE COCCYX. 
The coccyx1 (Fig. 144) consists of four, but sometimes of five and rarely of 
three, rudimentary vertebrae. These consist of little else than bodies tapering 
in size from above downward, so as to give the bone a triangular outline. They 
are ankylosed together, and oftentimes with the sacrum, in advanced life; but in 
middle life, especially in the female, the first is movable on the succeeding three 
and on the fifth sacral, with Avhich it is united by fibro-cartilage. 
1 Named from its resemblance to a cuckoo’s beak. THE SPINE AS A WHOLE. 
123 
The first coccygeal vertebra presents vestiges of a neural arch in two upward 
projecting cornua and two laterally projecting transverse 
or costal processes. The cornua, representing pedicles 
and superior articular processes, complete the last inter- 
vertebral foramina for the fifth sacral nerves by their 
connection with the sacral cornua. The transverse 
processes complete the notches below the lateral sacral 
angles, which are converted by ligamentous tissue into 
the fifth anterior sacral foramina. 
The second coccygeal vertebra presents two knobs 
dorsally and two laterally, vestiges of the neural arch 
and costal processes respectively. Three grooves sep- 
arate the four bodies. The ventral surface is concave, 
is closely related to the rectum, and attaches interiorly 
the levator ani muscle. To the thin lateral borders are attached parts of the 
coccygeus muscle and great sacro-sciatic ligaments, to the tip the external 
sphincter ani, and to the posterior surface some fibres of the gluteus maximus. 
Fig. 144,—The coccyx, ventral 
surface. (Testut.) 
THE SPINE AS A WHOLE. 
The vertebral or spinal column (Fig. 145) is the central axis of the skeleton, 
and occupies the median line of the trunk dorsally. It supports the head supe- 
riorly, the ribs laterally, and through them the weight of the upper extremities. 
It transmits the weight of these parts to the lower limbs through the hip-bones, 
with which the sacrum articulates. It also encloses and protects the spinal cord 
in the bony spinal canal, which is provided with a series of thirty intervertebral 
foramina for the exit of the spinal nerves. The average length of the spine 
from the atlas to the tip of the coccyx, following the curves, is twenty-eight 
inches in the male and twenty-seven inches in the female. About one-quarter 
of its length is made up of the intervertebral discs. 
The profile view presents four curves, convex forward in the cervical and 
lumbar regions, backward in the thoracic and sacral. The thoracic and sacral 
curves are primary, and occur in the early embryo, accommodating the thoracic 
and pelvic viscera. They are due to the shape of the bodies, while the secondary 
cervical and lumbar curves are due largely (if not entirely in the cervical) to the 
shape of the intervertebral discs. The latter two curves are compensatory to allow 
the erect position, and are developed after birth. Notice that the upper three 
curves pass imperceptibly into one another, while the junction of the lumbar and 
sacral curves makes an angle, the lumbosacral (or sacro-vertebral) angle, which 
forms the overhanging promontory of the pelvis. Weight is transmitted by the 
upper three curves and the first one or two pieces of the sacrum to the hip-bones 
and lower extremities. In the erect position the chords of these three curves 
are in the same vertical line, the line of gravity of the head, which passes through 
the odontoid process, the middle of the bodies of the second and twelfth thoracic, 
and the ventro-inferior edge of the last lumbar vertebra. The curves add greatly 
to the elasticity and strength of the column, and thus break shocks and increase 
its resistance to injury. In addition to these, a slight lateral curve, usually con- 
vex to the right, exists in the upper thoracic region, due probably to the greater 
muscular use of the right side of the body. Pathological exaggerations of all 
these curves may exist. Such a curvature is called scoliosis (“ curved ”) if lateral, 
kyphosis (“humpback”) if dorsal, and lordosis (“bend”) if ventral, the latter 
being usually compensatory to an ankylosed hip. 
The front view presents the bodies of the vertebrae becoming broader from the 
axis to the first thoracic, and from the fourth thoracic to the sacrum ; and becoming 
narrower from the first to the fourth thoracic, and from the first sacral to the tip 
of the coccyx. Thus, four pyramids are formed ; but the total surface area of the 124 
THE BONES. 
bodies steadily increases from above downward to the sacrum. The bodies are 
widest in the cervical and lumbar regions, where motion is most free. 
The rear view presents in the middle line the series of spines, nearly hori- 
zontal and about opposite the corre- 
sponding bodies in the cervical and 
lumbar regions, thus allowing free 
motion. The spines of the upper cer- 
vical vertebrae are not readily felt in 
the living body until we reach the 
seventh, or sometimes the sixth, spine. 
The upper thoracic spines are easily 
felt as subcutaneous, the lower thoracic 
and lumbar less so, for they lie in the 
deep spinal furrow bounded by the 
masses of muscles which occupy the 
vertebral grooves. 
At the sides of the spines are the 
vertebral grooves, bounded externally 
by a row of transverse processes. The 
floor of these grooves is formed by the 
laminae, connected by the ligamenta 
subflava, and by the articular pro- 
cesses with the mammillary processes 
in the lower part of the spine. The 
spinal canal is large and triangular 
in the cervical and lumbar regions, 
smaller and round in the thoracic 
region, and still smaller and flattened 
in the sacral region. 
The weakest point in the spine is 
found between the second and third 
cervical vertebrae, but the union of the 
thoracic and lumbar curves, or the 
twelfth thoracic vertebra and those on 
either side of it, is most liable to in- 
jury, for here a fixed part joins the 
most movable, there is a long leverage 
on both sides, and the transverse width 
is least. Notice that the plane be- 
tween any two vertebrae is interrupted 
by the upward and downward projection of the articular processes and other 
parts connected with the neural arch. Simple dislocation between two ver- 
tebrae is, therefore, almost impossible, unless perhaps in the cervical region, 
where the surfaces of the articular processes are more nearly horizontal. This is 
borne out in practice, where we find fracture-dislocation the common injury, the 
processes or neural arch being commonly fractured, if not the body itself. 
CERVICAL 
VERTEBRAE 
THORACIC 
VERTEBRAE 
LUMBAR 
VERTEBR/E 
SACRUM 
COCCYX 
Fig. 145.—The spinal column, right lateral view and 
dorsal view. (Testut.) 
Ossification of the Vertebrae. 
The vertebrae are preformed in cartilage (Fig. 146) around the notochord and 
enclosing the spinal cord. In most cases three primary centres of ossification 
occur—one on either side in the neural arch, and one in the body. The former 
unite together in the median line dorsally to form the arch. But sometimes this 
union fails for a distance, especially in the lumbar and sacral regions, leaving 
a gap through which a spina bifida may occur. The part formed by the 
ossific centres of the neural arch constitutes a varying amount of the lateral 
and dorsal aspects of the bodies (including the rib facets), separated for a time OSSIFICATION OF THE VEBTEBBJE. 
125 
from the rest of the body by the cartilaginous neuro-central suture. At birth 
a vertebra consists of three ossified parts—a body and the two lateral halves of 
the neural arch—connected by cartilage. Later five epiphyseal centres appear— 
three of which form tips for the spinous and transverse processes, and two form 
thin plates on the upper and lower sur- 
faces of the bodies. The mammillary 
processes of the lumbar vertebrae have 
each a small centre. The costal pro- 
UPPER EPIPHYSEAL 
DISC 
EPIPHYSIS ON 
TRANSVERSE PROCESS 
SRI NOUS 
BODY- 
"-LATERAL PART 
LOWER EPIPHYSEAL 
DISC 
EPIPHYSIS ON 
SPINOUS PROCESS 
Fig. 146.-Beginning of ossification in the carti- 
lagmous vertebra of a foetus. (Testut.) 
BODY 
Fig. 147.-Ossification of a thoracic vertebra. (After 
Testut.) 
cesses of the sixth and seventh cervical usually, of the first lumbar sometimes, and 
occasionally of other cervical vertebrae, are formed from separate centres. These 
may remain separate and become cervical or lumbar ribs. The various centres 
are not wholly united until about the twenty-fifth year. 
The atlas has regularly three centres—one for either half of the neural arch, 
formed by the lateral masses and the dorsal arch, and the third for the ventral 
arch. The axis (Fig. 148) ossifies much like other vertebra?, but its odontoid 
process has two laterally placed centres, which unite together and later with the 
body of the axis, though the centre of the intervening cartilage persists through 
HALF OF ODONTOID 
PROCESS \ 
EPIPHYSIS ON ODONTOID 
I PROCESS 
HALF OF ODONTOID 
/ PROCESS 
LATERAL 
PART 
/SPINOUS PROCESS 
LATERAL PART 
LATERAL PART 
LATERAL PART 
BODY 
LOWER EPIPHYSEAL' 
DISC 
BODY 
AURICULAR EPIPHYSIS 
COSTAL PART 
COSTAL PART 
AURICULAR EPIPHYSIS 
Fig. 148.—Ossification of the axis. (After Tes 
tut.) 
Fig. 149.—Ossification of the sacrnm—horizontal sec- 
tion through first piece. (After Testut.) 
life. An epiphyseal centre also occurs for the apex of the odontoid process. 
The sacrum (Fig. 149) also ossifies essentially like other vertebrae, except that 
there are separate centres for the costal processes of the upper three vertebrae, 
and the auricular articular surfaces have two secondary centres each. The inter- 
vertebral discs ossify on the surface, but not in the centre, from the eighteenth 
to the twenty-fifth year, from below upward. The coccyx is cartilaginous at birth, 
and each segment has commonly but one centre. The lower three ankylose before 
middle life, and these with the first still later, while bony union with the sacrum 
belongs to advanced life. 
Variations.—Two or a single lateral centre may exist in a vertebral body, 
forming a divided or a half vertebra. In the fifth lumbar vertebra the neural 
arch often has four centres. The pairs on either side may fail to unite with each 
other, causing a separation of the laminae and inferior articular processes from the 
pedicles, etc. 
Serial Morphology of the Vertebrae.—The similarity of construction of the 
vertebrae in each region of the column is evident from the study of their develop- 
ment and ossification. Centra or bodies are present for all the vertebrae in man, 126 
THE BONES. 
but that of the atlas is dissociated from its neural arch and joined to the body of 
the axis as the odontoid process. The anterior arch of the atlas probably belongs 
to a series of hypophyses or subvertebral wedge-bones (found in lizards, etc.). 
Nothing need be said of the neural arches and spines, except that they are incom- 
plete or wanting in the lower sacral and coccygeal regions. The articular processes 
are not morphologically important; but the upper three are not homologous with 
other articular processes, but rather with the lateral parts of the bodies formed by 
the neural arches. The transverse processes, so called, present more difficulty 
as well as interest. We find two transversely directed processes—a ventral or 
costal process and a dorsal or transverse process proper. They present themselves 
in the simplest form in the thoracic region, where the ventral or costal process is 
a separate rib, which by articulation with the transverse process encloses an arte- 
rial foramen, the costo-transverse. This foramen is seen also in the cervical 
region, where, however, the costal processes are ankylosed with the transverse 
processes and bodies, except when, in the lower cervical vertebra?, they form 
separate cervical ribs. In the lumbar region the costo-transverse foramen is only 
indicated by a group of holes at the base of and between the transverse process 
and the accessory tubercle. The latter represents the tip of the suppressed dor- 
sally situated transverse process, while the former represents a costal process, and 
in the first lumbar sometimes exists as a separate lumbar rib. In the upper three 
or true sacral vertebrae the large ventral costal processes and the dorsal trans- 
verse processes unite to form the lateral masses which articulate with the hip- 
bones by means of their costal parts. The mammillary processes (best seen in 
the lumbar and lower thoracic regions) are rudiments of the much-elongated 
articular processes in some animals, as the dog, etc. 
THE THORAX. 
Besides the thoracic vertebrae already described, the skeleton of the thorax 
(“ breast-plate ”) consists of the sternum, ribs, and costal cartilages. 
THE STERNUM. 
cutaneously in the middle of the ventral wall ot 
the thorax. It is connected with the thoracic part 
of the vertebral axis by the cartilages of the first 
seven ribs on each side, and, through the attach- 
ment of the clavicle, it connects the shoulder- 
girdle and the upper extremity to the vertebral 
axis. It lies obliquely, so that its lower end is 
farther forward than the upper. The upper end 
corresponds to the lower border ot the second, the 
lower end to the middle of the ninth, thoracic 
vertebra. 
It consists of three parts, derived from six 
original segments. The first segment, or upper 
part, remains separate through life as the manu- 
brium {“ handle”) or pre-sternum, united by 
fibro-cartilage to the succeeding four segments 
which form the gladiolus (“ little sword ”) or 
body (meso-sternum). The sixth or lower seg- 
ment, forming the xiphoid or ensiform {“ sword- 
like ”) process (meta-sternum), remains cartilagin- 
ous and distinct to advanced age, when it may 
ossify in whole or in part, and ankylose with the body. It is usually bent, and 
The sternum or hreast-bone (Fig. 150) is a long, thin, flat bone, situated sub- 
Fig. 150.—The sternum, ventral 
aspect. (Testut.) THE BIBS. 
127 
often perforated, notched, or bifid. It lies in a plane behind that of the body 
of the sternum and the cartilages of the seventh ribs. The sternum is longitu- 
dinally convex in front, concave behind, and presents transverse ridges where the 
segments unite. It consists of loose cancellous tissue with a thin shell of com- 
pact bone. 
The manubrium forms the upper border of the sternum, which is deeply 
notched in the middle (interclavicular notch), and presents at its lateral angles two 
depressed surfaces looking upward, outward, and backward, where the clavicles 
articulate. On each side of the manubrium, at the widest part of the sternum, is 
a rough, triangular surface for union with the cartilage of the first rib. Below 
this the sternum rapidly narrows to the junction of the manubrium and the body, 
indicated by a prominent transverse ridge, easily felt through the skin and import- 
ant as a landmark. Here the second costal cartilage articulates with a surface 
formed of two demi-facets, one on the manubrium and one on the body. The 
third, fourth, and fifth costal cartilages articulate with the sides of the body at 
the ends of the transverse ridges between the segments.1 The sixth and seventh 
costal cartilages articulate with the sloping and narrow sides of the lower segment 
of the body, the facet for the seventh cartilage being completed by a demi-facet on 
the ensiform process. The spaces between the articular facets correspond to the 
intercostal spaces, and narrow from above downward. 
Muscles Attached.—ln front: laterally, to the manubrium and body, the pec- 
toralis major ; below the notch for the clavicle, the sterno-cleido-mastoid ; to the 
base of the ensiform process, the rectus abdominis; to the sides and tip of the 
ensiform process, the aponeurosis of the oblique and transverse abdominal mus- 
cles. Behind : near the superior angles, the sterno-hyoid and sterno-thyroid ; 
laterally, in the lower four segments, the triangularis sterni; to the ensiform pro- 
cess, the diaphragm. On the sides: between the facets, the internal intercostals. 
The sternum articulates with seven, and occasionally eight, costal cartilages 
and the clavicle on each side. 
The sternum is subcutaneous at the bottom of the sternal groove, which is due 
to the lateral prominences of the pectoral muscles, and is limited above by the 
interclavicular notch and below by the infrasternal depression, due to the promi- 
nence of the seventh costal cartilages above the level of the ensiform process. 
The proportionate length of the body is greater in the male than in the female. 
Its average length is six inches in the adult male, somewhat less in the female. 
Development.—The sternum is formed by the fusion of the ventral cartilag- 
inous ends of the upper ribs into two lateral bars, which later fuse together 
mesially, except in rare cases where a cleft sternum exists. 
Ossification is irregular, but usually the first two segments present a single 
primary centre, while two laterally placed centres commonly occur in the succeed- 
ing segments. By the failure of the latter to unite across the median line a 
median foramen or a vertical fissure may be left. 
THE RIBS. 
The ribs (cost®) extend in twelve pairs from the thoracic vertebrae in an out- 
ward and forward curve toward the median line in front. They form the lateral 
walls of the thoracic cage, and are prolonged in front by the costal cartilages. 
As the upper seven pairs of the latter pass to the sternum, the corresponding 
seven pairs of ribs are called true or sternal ribs, while the lower five pairs are 
called false or asternal ribs. Of the latter, the lower two pairs are called floating 
ribs, as their forward ends are free, white those of the three pairs above them are 
connected together. The length of the ribs increases from the first to the eighth, 
and thence it decreases to the twelfth. The greatest breadth is found at the sternal 
end. The ribs are highly elastic, owing to their slenderness and curvature. 
1 The second, third, fourth, fifth, and seventh costo-sternal articulations correspond to the articu- 
lations of the heads of their ribs with two vertebrae. 128 
THE BONES. 
The general characters of typical ribs are best marked in ribs like the seventh, 
near the centre of the series. A typical rib (Fig. 151) consists of an enlarged 
HEAD 
•TUBERCLE 
ARTICULAR SURFACE FOR 
COSTAL CARTILAGE 7i 
ANGLE 
SHAFT 
ANGLE 
•TUBERCLE 
Fig. 151.—A typical rib of the right side. The upper picture shows the inner surface, the lower one the 
outer surface. (Testut.) 
HEAD 
NECK 
vertebral end, or head, joined by a constricted neck to a shaft, presenting a 
tubercle, an angle, and a sternal end. The head shows two articular facets, sepa- 
rated by a slight horizontal ridge, to which the interarticular ligament from the 
intervertebral disc is attached. The facets articulate with the two demi-facets 
on the sides of the bodies of two contiguous vertebrae. The lower facet is the 
primary and larger one, and articulates with the vertebra which corresponds to 
the rib in number, and it is the only facet where there is but one. The neck 
is that part between the head and the tubercle. It is rough behind and along the 
upper and lower borders for the costo-transverse ligaments, and forms the ventral 
boundary of the costo-transverse foramen. The tubercle is divided by an oblique 
groove into an inner and lower smooth portion for articulation with the front of 
the tip of the transverse process of the vertebra of the same number as the rib, 
and an outer and upper rough part for the posterior costo-transverse ligament. 
The body, or shaft, beginning with the tubercle, extends to the cupped sternal end, 
which receives the costal cartilage. It is laterally compressed, so as to present 
inner and outer surfaces and upper and lower borders. On the inner aspect of the 
inferior border is the subcostal groove, which lodges the intercostal vessels and 
nerves. It is best marked near the angle, and is limited above by a ridge which 
is continuous with the inferior border of the neck and attaches the internal inter- 
costal muscle. The inferior border, which begins near the angle, attaches the 
external intercostal muscle ; the superior border attaches both intercostal muscles ; 
the convex external surface affords attachment for muscles. 
The shaft is curved around a vertical axis, or rather two axes. The dorsal 
and sharper curve is in line with the neck, and extends outward to the angle, 
where the rib takes a sudden bend, in front of which the curve is more gradual. 
The curvature of the ribs decreases from the first, the most curved, to the twelfth, 
the least curved. The back of the angle is rough,for the attachment of the ilio- 
costalis muscle and its upward continuation. At the angle the ribs from the 
third to the twelfth are also bent on a horizontal axis, so that if they be rested 
on their lower borders the head end of the ribs curves upward from the angles. 
This curve increases from the third to the seventh, and thence decreases to the 
twelfth. The head end of the first and twelfth bend slightly downward; that of 
the second is in line with the shaft. This curve is sometimes spoken of as a 
twisting of the rib on itself. It increases the obliquity of the ribs as far as the 
seventh or eighth. 
Peculiar Ribs.—The first rib (Fig. 152) is the least oblique, and is so placed 
that its surfaces present upward and downward. If laid on its lower surface, the THE COSTAL CARTILAGES. 
129 
head end does not bend up, but slightly down. The small head has but a 
single facet, the neck is long and narrow, and the tubercle and angle coincide. 
On the broad superior surface and 
close to the centre of the internal 
border is a rough mark, the scalene 
tubercle, the origin of the scalenus 
anterior muscle. It separates a groove 
in front for the subclavian vein from 
one behind for the subclavian artery. 
Behind the latter groove are attached 
the first digitation of the serratus 
raagnus externally and the scalenus 
medius internally. The subcostal 
groove is wanting. The second rib 
(Fig. 152) has no upward curve of 
the head end, but it lies almost per- 
fectly flat. The upper surface looks 
obliquely outward, and has a promi- 
nent roughness for the serratus mag- 
nus. The angle is but slightly marked. 
The tenth rib has usually a single facet 
on the head, sometimes two facets. The 
TUBERCLE 
NECK 
TUBERCLE 
•HEAD 
'HEAD 
SECOND. 
RIB 
GROOVE 
►FOR SUBCLA- 
VIAN ARTERY 
SCALEN E 
TUBERCLE 
S GROOVE FOR 
JSUBCLAVIAN VEIN 
Fig. 152.—The first and second ribs of the right side 
viewed from above. (Testut.) 
eleventh rib has but one facet, no neck or tubercle, a feeble angle, and a shallow 
subcostal groove. The twelfth rib resembles the eleventh, but has no angle and 
no subcostal groove. It is shorter, and may be rudimentary, measuring less than 
1 inch in length—an important point in lumbar incisions. It either lies flat 
on its lower border, or its head end may bend slightly downward. Its outer 
surface may incline somewhat downward. 
Variations— Thirteen ribs may occur on one or both sides, from the presence 
of a cervical or lumbar rib. The additional ribs are developed from the costal 
processes, and are usually short and imperfect, especially when lumbar. Very 
rarely a thirteenth thoracic rib occurs. The tenth rib may have no articular facet 
on the tubercle. 
Ossification.—The ribs are preformed in cartilage, and have a single primary 
centre near the angle. Much later two epiphyseal centres appear—one for the 
head and one for the tubercle—which become united to the rest of the bone by 
the twenty-fifth year. 
The costal cartilages are bars of hyaline cartilage prolonging the ribs toward 
the sternum. In direction the first passes slightly downward as well as inward, 
the second is horizontal, and the rest, down to the eleventh, are directed suc- 
cessively more and more upward in passing inward. Their breadth diminishes 
from the first to the twelfth, and is greater at the costal than at the sternal end 
of each cartilage. Their length increases to the seventh, and thence becomes 
gradually less. In shape they resemble the sternal ends of the ribs. The inner 
extremities of the upper seven arc connected with the sternum, the first being 
fused with it, the others articulated. The cartilages of the upper three false ribs 
are attached at their upturned, narrow, inner ends to the lower border of the 
cartilages next above. The cartilages of the floating ribs are short, and have a 
pointed free end. The borders and surfaces afford attachment to muscles—inter- 
nally to the triangularis sterni, from the second to the sixth, and to the diaphragm 
and transversalis in the lower six. The costal cartilages represent unossified 
epiphyses of the rib-shafts. The costal cartilages are covered by a thick peri- 
chondrium, beneath which superficial ossification may occur in advanced life. 
This change occurs quite regularly in the first cartilage, but in the others less 
THE COSTAL CARTILAGES 130 
THE BONES. 
commonly, at a later period, more particularly in front, and more often in the 
male than in the female. 
THE THORAX AS A WHOLE. 
The bony thorax (Figs. 153, 154) forms an irregular, truncated cone, com- 
pressed from before backward. It is longer behind than in front, so that its 
upper small reniform aperture, or inlet, looks slightly forward as well as upward, 
and the plane of the lower opening, or base, also looks forward and downward. 
Fig. 153.—The skeleton of the thorax, front view. (Testut.) 
The margin of the irregular base is formed by the two curved lines of the edges 
of the lower six pairs of ribs and cartilages, converging to the xiphi-sternal 
junction, and bounding the subcostal angle, in the centre of which projects the 
ensiform process. The dorsal ivall, formed by the thoracic vertebrae and the ribs 
as far as the angles, is convex from above downward. The backward curve of 
the ribs forms a broad furrow, the vertebral groove, between the angles of the ribs 
and the vertebral spines, which lodges tire erector-spinse muscle group. This 
backward position of the angles of the ribs, about on a level with the thoracic 
spines, causes the flatness of the back which allows the supine position character- 
istic of man. The ventral wall, formed by the sternum and costal cartilages, is 
inclined downward and forward at an angle of 20° or 25° with the vertical plane, 
and is only slightly convex. The sides, formed by the ribs, from the angles to 
the cartilages are convex from above downward; much more so from before back- 
ward. From about the ninth rib down they slant inward. The interior corre- 
sponds in shape to the exterior, except for the median projection of the vertebral 
bodies, which makes the median diameter less than that on either side, and only 
little more than one-half of the external median diameter. The lateral grooves 
formed by the forward projection of the vertebral bodies and the backward 
curvature of the ribs lodge about as much of the lungs as lies in front of a 
transverse plane tangent to the bodies. This circumstance, together with the THE CLAVICLE. 
131 
wide transverse diameter characteristic of man, throws the weight farther back, 
and makes easier the balance around the spinal axis in the erect position. 
The ribs are more and more oblique from above downward as far as the 
seventh or lower—a fact due in part to the increasing downward curvature from 
the head to the angle, and in part to the increasingly lower position of the trans- 
verse processes of the lower thoracic vertebrae. This increasing obliquity of the 
Fig. 154.—The skeleton of the thorax, dorsal view (Testut.) 
ribs makes the eleven intercostal spaces wider at the sides than behind. These 
spaces contract again somewhat in front from the third to the eighth. They are 
widest in the upper three spaces, and wider in inspiration than in expiration. It 
should be remembered that the circumference of the right half of the thorax is 
usually about half an inch larger than that of the left. Note that the lower pal- 
pable end of the gladiolus is on a level with the lowest part of the fifth rib. At 
birth the thorax may measure even more from before backward than transversely, 
as is the case with quadrupeds. This is due to the absence of the angles and to 
the less curvature of the ribs at this period. In the female the thorax is rela- 
tively shorter, and deeper from before backward, though the latter diameter is 
actually less than in the male. 
THE BONES OF THE UPPER LIMB. 
The skeleton of the upper limb comprises the clavicle and scapula, forming 
the pectoral arch or shoulder-girdle, the humerus in the arm, the radius and ulna 
in the forearm, and the carpal, metacarpal, and phalangeal bones in the hand. 
The clavicle (“little key”) or collar-hone (Figs. 155, 156) passes outward and 
backward from the top of the sternum to the acromion process of the scapula, 
and forms the connecting link between the trunk and the upper limb, affording a 
THE CLAVICLE. 132 
THE BONES. 
fulcrum in the movements of the latter. It is curved like an italic /. Its inner 
two-thirds, prismatic or cylindrical, is convex forward like the thorax below it; 
ARTICU- 
LAR SURFACE 
STERNAL 
END 
ACROMIAL 
END 
Fig. 155.—The right clavicle, upper surface and sternal end. (Testut.) 
its outer third, flattened from above downward, is concave forward, corresponding 
to the hollow between the thorax and the shoulder. 
The superior surface is flat and broad in its outer third, where it is overlapped 
by the attachment of the trapezius behind and the deltoid in front, with a subcu- 
taneous area between. In the inner two-thirds it is rounded and subcutaneous 
externally, and marked by the attachment of the sterno-cleido-mastoid internally. 
The ventral surface in its outer third is merely a rough border for the origin of 
the deltoid, near the inner limit of which is the deltoid tubercle, when present. 
In its inner two-thirds it is broader, and rough for the origin of the pectoralis 
major muscle. The inferior surface presents the rough trapezoid line, running 
inward and backward from near the front of the outer end to the conoid tubercle, 
near the dorsal border at the junction of the outer fourth and the inner three- 
fourths. These attach respectively the trapezoid and conoid portions of the coraco- 
clavicular ligament. Internal to the conoid tubercle is a shallow'groove for the 
insertion of the subclavius muscle. ISiear the sternal end is a rough impression 
for the rhomboid ligament which binds the clavicle to the first rib. Internal to 
this impression is a facet where the clavicle plays on the first costal cartilage. This 
ACROMIAL, 
END A 
STERNAL 
\ END 
TRAPEZOID^ 
LINE 
CONOID 
TUBERCLE 
RHOMB. IMPR. 
Fig. 156.-—The right clavicle, under surface. (Testut.) 
facet is continuous with the sternal facet, and close beside it the sterno-hyoid mus- 
cle is attached. The dorsal surface, like the ventral, is merely a rough border 
in its outer third, where the trapezius muscle is inserted. In its inner two-thirds 
it is broader and smooth, and arches over the subclavian vessels and the brachial 
plexus. The nutrient foramen is usually seen passing outward near the middle 
of this surface, but sometimes it is on the inferior surface. Part of the clavicular 
attachment of the sterno-cleido-mastoid is found at the sternal end of this surface. 
The border1 separating the dorsal and inferior surfaces passes from the conoid 
tubercle to the rhomboid impression. 
The sternal end is expanded into a triangular or oval articular surface, which 
plays upon the interarticular fibro-cartilage between it and the sternal facet. Its 
rough borders attach the sterno-clavicular and interclavicular ligaments. The 
acromial end presents an oval articular surface, elongated from before backward, 
INo other border needs description. The clavicle is often described as having three surfaces 
and three borders in its inner two-thirds, and two in its outer third. In this less common or less 
accurately described condition the ventral border is expanded in its centre for the attachment of the 
pectoralis major muscle. THE SCAPULA. 
133 
and bevelled inferiorly, which articulates with the acromion process of the scapula. 
Its upper surface is on a little higher level than that of the acromion. 
The clavicle has no medullary cavity, but is composed of cancellous tissue with a 
shell of compact bone. It is more or less subcutaneous throughout, but especially so 
in the intermuscular interval near its centre. Fracture is very common, especially 
at the junction of its two curvatures (inner two-thirds and outer one-third). The 
clavicle is longer, stronger, rougher, and more curved in the male than in the 
female, and on the right side than on the left. In the male it also inclines 
slightly upward as it passes outward. 
Ossification.—The clavicle is the first bone to ossify. It begins in membrane, 
but quickly extends into the underlying cartilage of the precoracoid bar. An 
epiphysis, appearing at the sternal end between the eighteenth and twentieth 
years, is united to the shaft about the twenty-fifth year. 
THE SCAPULA 
The scapula (Figs. 157, 158) is a large, flat, triangular bone, forming the 
dorsal part of the shoulder-girdle. It rests upon the upper and back part of the 
thorax, and from it is suspended the 
humerus. Its surfaces are ventral and 
dorsal; its borders superior, internal, 
and external; and from its external 
angle or head, which bears an articular 
surface, projects the eoracoid process. 
The spine, prolonged into the acromion 
process, projects from its dorsal surface. 
The ventral surface, or venter, pre- 
sents the subscapular fossa, a deep con- 
cavity most marked above. From the 
inner two-thirds of this, which is 
marked by three or four oblique ridges, 
the subscapularis muscle arises. This 
fossa is separated from the internal 
border by a linear area, which, with its 
two triangular expansions opposite the 
upper and lower angles, attaches the 
serratus magnus muscle. Externally, 
the fossa is limited by a smooth, promi- 
nent ridge descending from the head 
of the bone. From the narrow groove 
between this ridge and the external 
border arise some fibres of the sub- 
scapularis. The convex dorsal surface 
or dorsum is unequally divided by a 
prominent ridge, the spine, into an 
upper smaller supraspinous fossa, and 
a lower larger infraspinous fossa, giving origin to the supraspinatus and infra- 
spinatus muscles, respectively. The two fossee communicate around the outer 
border of the spine by means of the great scapular notch, which corresponds to the 
neck of the bone, and transmits the suprascapular nerve and vessels from one fossa 
to the other. An oblique ridge running from below the glenoid fossa to the verte- 
bral border just above the inferior angle separates the infraspinous fossa from the 
external border by a narrow space, which attaches the teres minor muscle above 
and the teres major on the broader portion below. 
The massive triangular spine of the scapula commences about the upper fourth 
of the vertebral border as a smooth, expanded, triangular surface, covered by a 
bursa over which the lower part of the trapezius glides to be inserted into a 
ARTICULAR FACET 
FOR CLAVICLE 
SU PRASCAPULAR 
NOTCH 
SUPERIOR ANGLE 
Fig. 157.—The right scapula, ventral view. (Testut.) 134 
THE BONES. 
tubercle beyond. From this point, projecting backward and upward, and 
becoming more and more elevated, it extends outward and a little upward to 
the middle of the neck of the scapula. Thence it is continued forward and out- 
ward as the flat, quadrate acromion (“ summit of the shoulder ”) process, over- 
hanging the shoulder-joint. The upper and lower smooth, concave surfaces of 
the spine form part of the supra- and infraspinous fossae respectively. Of the two 
SUPERIOR ANGLE 
I 
FOSSA 
Fig. 158.—The right scapula, dorsal view. (Testut.) 
unattached borders the short, smooth, and concave external border arises at the 
neck of the scapula, where it bounds the great scapular notch, and is continuous 
with the under surface of the acromion. The more prominent subcutaneous dorsal 
border, or crest, is rough, broad, and serpentine. Commencing at the above-men- 
tioned triangular surface, it passes outward to become continuous with the rough, 
subcutaneous upper surface of the acromion. The upper lip of the crest is con- 
tinuous with the inner border of the acromion, and to them is attached the trape- 
zius muscle as far as the oval facet for the outer end of the clavicle, on the inner 
border of the acromion near its tip. The lower lip of the crest is continuous 
with the outer border of the acromion, with which it forms an angle, the acromicd 
angle, and from them the deltoid takes origin. The apex of the acromion attaches 
the coraco-acromial ligament, and its under surface, continuous with the upper 
surface and outer border of the spine, is smooth and covered by a bursa. 
The internal or vertebral border (or base) is long and irregularly convex. 
Opposite the commencement of the spine it bends more sharply, and here 
attaches the rhomboideus minor muscle, while below this area the rhomboideus 
major is attached by a fibrous arch, and above it the levator scapulae is inserted. 
The superior border, short, sharp, and concave, extends from the superior angle 
to the base of the coracoid process, where it presents the suprascapular notch, 
converted into a foramen by the transverse ligament (sometimes by a spicula of 
bone). The foramen transmits the suprascapular nerve, and from the ligament 
and the adjacent border the omo-hyoid muscle arises. The external or axillary 
border is quite thin, and just below the glenoid fossa presents a rough impression, 
from which the long head of the triceps arises. A little below this is a groove for 
the dorsal artery of the scapula. 
The long, rounded, thick inferior angle is often called the angle of the scapula. THE HUMERUS. 
135 
To its dorsal aspect some fibres of the latissimus dorsi muscle are frequently 
attached. The external angle presents the head, supported on a slightly constricted 
neck, and bearing the articular glenoid cavity for the humerus. The glenoid cavity 
is shallow and pear-shaped, with the narrow end above, and indented on its ven- 
tral lip above its centre. It looks outward, upward, and forward. To its rim is 
attached the glenoid ligament, which deepens the shallow cavity, and outside of 
this the capsular ligament is attached. The long head of the biceps arises from 
its upper extremity. From the upper border of the neck the thick, strong cora- 
coid (“like a crow’s beak”) process rises nearly vertically for a short distance, 
and then bends sharply forward and outward in front of, and more or less parallel 
with, the acromion. From the tip of the process arise the short head of the 
biceps, the coraco-brachialis, and the costo-coracoid ligament. To its inner border 
the pectoralis minor muscle is attached, and to its outer border the coraco-acromial 
ligament. Its superior surface is rough, and affords attachment, near the base, to 
the coraco-clavicnlar ligament (conoid and trapezoid portions). 
When the arm hangs by the side the scapula rests upon the ribs, from the 
second to the seventh inclusive, and the inner end of its spine corresponds to the 
third thoracic spine1 or the space below it. The distance between the spines of the 
vertebrse and the vertebral border averages two inches. The tip of the coracoid 
process is palpable below the clavicle and internal to the humeral head, except in 
tat subjects. The dorsal border of the spine, the upper surface of the acromion, 
and the lower part of the vertebral border are also subcutaneous. 
Ossification occurs in cartilage from two primary and five secondary centres, 
from the former of which the body and coracoid process are formed. The coracoid 
joins the body about the fifteenth year, when two centres appear in the acromion, 
which soon unite together and join the spine about the twentieth year, though 
sometimes this union fails, and the acromion is movable on the spine. Two other 
centres appear in the cartilage along the vertebral border, and another between 
the glenoid cavity and the coracoid process. 
Morphology.—The coracoid process represents the coracoid bone, or ventral 
bar of the shoulder-girdle of other animals. Its ventral end has degenerated 
into the costo-coracoid ligament. The glenoid fossa is the meeting-point of the 
coracoid and the dorsal segment or scapula. The precoracoid bar of the shoulder- 
girdle is replaced by the clavicle in man. 
THE HUMERUS. 
The humerus (Figs. 159, 160) constitutes the skeleton of the arm, and extends 
downward and slightly inward from the shoulder to the elbow. It presents, like 
all long bones of the limbs, an upper and a lower extremity and a shaft. 
The large upper extremity includes the head, neck, and two tuberosities. The 
large cartilage-clad head represents about one-third of a sphere, whose vertical 
diameter is slightly longer than the transverse. It is directed inward, upward, 
and backward, at an angle of 130° with the axis of the shaft, to articulate with 
the glenoid cavity of the scapula. The anatomical neck is the slight constriction 
below and external to the head, to which the capsular ligament is attached. 
Superiorly, it is a mere groove between the head and the tuberosities. The latter 
are separated from one another by the commencement of the bicipital groove. 
The great tuberosity, the higher and more dorsally placed, is continued up from 
the outer surface of the shaft nearly to the level of the head. Of the three facets 
on its upper and dorsal aspect, the upper attaches the supraspinatus, the middle 
the infraspinatus, and the lower the teres minor muscle. The prominent small 
tuberosity looks forward and attaches the subscapularis muscle. The surgical neck, 
so called from the frequency of fracture here, is where the shaft joins the upper 
extremity. 
The shaft, cylindrical above, transversely expanded and triangular below, is 
1 And also to the fissure between the upper and lower lobes of the lung. 136 
THE BONES. 
twisted inward in descending. It presents external, internal, and dorsal surfaces 
separated by external, internal, and ventral borders. The external and internal 
borders, slightly marked above, become prominent below as the external and 
internal supracondylar ridges, which descend to the condyles. From each of 
SMALL 
TUBEROSITY 
HEAD 
'SURGICAL 
NECK 
MUSCULO- . 
SPIRAL GROOVE 
EXTERNAL. 
CONDYLE 
" CONDYLE 
INTERNAL 
CONDYLE" 
EXTERNAL 
CONDYLE 
Fig. 159.—The right humerus, front view. (Testut.) 
Fig. 160.—The right humerus, rear view. (Testut.) 
these an intermuscular septum arises, and from the upper two-thirds of the 
external ridge arises the brachio-radialis muscle, and from its lower third the 
extensor carpi radialis longus. The external border extends down from the back 
of the great tuberosity, and is interrupted near the middle of the shaft by the 
musculo-spiral groove. The internal border commences above just below the 
head,1 and near its centre presents a rough impression, extending on to the adja- 
cent inner surface, for the ooraco-brachialis muscle. The ventral border starts 
above from the front of the great tuberosity as the outer lip of the bicipital 
groove, and ends below in the ridge separating the trochlea and capitellum. The 
internal surface in its upper third presents the vertical bicipital groove, which 
lodges the long tendon of the biceps. Its two rough lips give insertion, the outer 
to the pectoralis major, the inner to the teres major below, and to the latissimus 
dorsi above, which is also attached to the floor of the groove. A little below the 
centre is seen the nutrient foramen, directed downward. The external surface pre- 
1 It is usually described as continuing the inner lip of the bicipital groove. THE ULNA. 
137 
sents just above the centre a rough V-shaped impression for the deltoid insertion, 
immediately below which the musculo-spiral groove is seen winding downward 
and forward after grooving the outer border. The hind or lower portion of this 
groove is traversed by the musculo-spiral nerve and the superior profunda ves- 
sels, while its upper part, together with the lower half of the external and internal 
surfaces and of the ventral border, gives origin to the brachialis muscle. The 
dorsal surface, unequally divided by the musculo-spiral groove, attaches above 
the latter the external head of the triceps, and below it the internal head. 
The lower extremity is transversely elongated, flattened from before backward, 
and curved forward. From within outward notice the following parts : The 
prominent internal condyle is flattened and inclined slightly backward, forming 
a shallow groove behind, traversed by the ulnar nerve. From the front of its 
extremity arise the pronator radii teres and the common tendon of the superficial 
flexor muscles in the forearm, below which the internal lateral ligament is 
attached. The articular surface is divided by a ridge (which corresponds to the 
interval between the radius and ulna) into a large internal and a smaller external 
part. The internal part, or trochlea. (“ pulley ”), is a pulley-like surface, grooved 
in the middle, which articulates with the great sigmoid cavity of the ulna. It is 
obliquely placed, so that it ascends upward and outward behind, and its inner 
margin descends much lower than its outer. It is broader behind than in front, 
and its surface forms three-fourths or more of a circle. Above it notice the large 
olecranon fossa behind and the smaller coronoid, fossa, in front, receiving, respect- 
ively, the olecranon process in extension and the coronoid process in flexion of 
the forearm. The external part, the capitellum (“ little head ”), or radial head, is 
a small rounded surface, which, with the groove internal to it, articulates with the 
head of the radius. It looks forward, and is confined to the ventral and a part 
of the inferior surface. Above it in front is a slight depression for the edge of 
the head of the radius in complete flexion of the elbow. The external condyle, on 
the same horizontal plane with, but less prominent than, the internal, attaches 
interiorly the common tendon of the forearm extensor muscles, the external lateral 
ligament, and, more dorsally and internally, the anconeus muscle. 
In its natural position the humerus is rotated inward so much that the internal 
condyle, which is in line with the head above, looks more backward than inward. 
The principal or longest axes of the upper and lower extremities make an angle of 
torsion of 30° with one another, which represents the amount of twisting of the 
bone. The humerus averages 13 inches in length in the male and 12 inches in 
the female. The condyles alone are subcutaneous, and are important as land- 
marks. 
Varieties.—The thin plate of bone between the olecranon and coronoid fossae 
is sometimes perforated, forming the supratrochlear foramen. A small hook-like 
supracondylar process, connected by a fibrous band with the internal condyle 
about 2 inches below, is occasionally found. It represents a similar bony fora- 
men in many animals, and, like it, transmits through the arch the median nerve 
and often the brachial artery or a large branch of it. 
Ossification occurs from a primary centre in the shaft and six or seven second- 
ary centres in the extremities. In the upper extremity centres appear in the 
head, great tuberosity, and sometimes in the small tuberosity, which, after fusing 
together, join the shaft about the twentieth year. In the lower extremity centres 
appear in the trochlea, capitellum, and outer and inner condyles, the three former 
of which, after coalescing, unite with the shaft in the seventeenth year, the inner 
condyle somewhat later. 
The ulna (“elbow-bone”) (Figs. 161, 162), the inner bone of the forearm, is 
parallel with, but longer than, the radius by nearly the length of the olecranon. 
It is inclined downward and outward from the humerus, so that the great tuber- 
THE ULNA. 138 
THE BONES. 
osity and capitellum of the humerus and the lower end of the ulna are in a 
straight line. 
The irregular upper extremity is the thickest part, and presents for articulation 
with the trochlea of the humerus the great sigmoid (“ sigma-like ”) cavity. This 
looks forward and upward, is concave from above downward, and presents a 
longitudinal ridge which fits into the groove of 
the trochlea. At the middle of the cavity is a 
constriction (sometimes a groove) which repre- 
sents the limit between the upper and hind part 
formed by the olecranon, and the lower and fore 
part formed by the coronoid process. 
The thick olecranon (“ elbow-head ”) process 
forms the highest part of the ulna. On its broad 
upper surface the triceps is inserted dorsally, 
while the front of this surface projects in a beak 
which overhangs the great sigmoid cavity, and fits 
into the olecranon fossa of the humerus in exten- 
sion of the elbow. The dorsal surface is triangular 
and subcutaneous, except for a bursa covering it. 
The margins of the ventral or articular surface 
attach the internal and posterior ligaments of the 
elbow. From a tubercle on its inner side part 
of the flexor carpi ulnaris arises. The coronoid 
(“ crown-like ”) process projects forward from the 
upper end of the shaft. Its sharp ventral edge, 
or apex, is received into the coronoid fossa of the 
humerus in flexion. The ventral and internal 
edges of its upper or articular surface attach the 
anterior and internal ligaments of the elbow. 
The inferior or ventral surface is rough, and, 
together with the tuberosity at its lower end, 
gives insertion to the brachialis. The oblique 
ligament is attached to the outer part of the 
tuberosity. On the inner edge of the ventral 
surface is a tubercle from which part of the 
flexor sublimis digitorum arises, and from the 
ridge below this parts of the pronator radii teres 
and flexor longus pollicis arise. On the outer 
side of the upper end of the coronoid process, 
ANTERIOR 
BORDER 
STYLOID 
'PROCESS 
STYLOID _ 
process" 
Fig. 161—The bones of the right fore- 
arm, rear view. (Testut.) 
and continuous with the great sigmoid cavity, is the concave, oval, small sigmoid 
cavity for articulation with the side of the head of the radius. 
The shaft tapers from above downward. It is curved inward above, outward 
below, as well as slightly backward. Triangular in the upper three-fourths, more 
rounded below, it presents the following parts : The anterior or ventral border 
runs from the inner margin of the coronoid process to the front of the styloid 
process, becoming continuous with the oblique pronator ridge in its lower fifth. 
The posterior or dorsal border begins at the apex of the subcutaneous triangle 
behind the olecranon, and runs sinuously to the back of the styloid process, 
becoming less distinct below. The external or interosseous border, faintly 
marked below, is sharply marked in the middle, and attaches the interosseous 
membrane. It bifurcates above into two lines which pass to the two ends of the 
small sigmoid cavity, and enclose a triangular space which, with its prominent 
dorsal border, called the supinator ridge, gives origin to the supinator muscle. The 
ventral surface gives origin in the concave upper three-fourths to the flexor pro- 
fundus digitorum, and in the lower fourth, below the oblique pronator ridge, to 
the pronator quadratus. In the middle third is the nutrient foramen, directed 
upward. The internal surface gives origin to the flexor profundus digitorum in THE RADIUS. 
139 
its upper three-fourths, below which it is subcutaneous. The dorsal surface is 
inclined slightly outward. To a triangle on its upper fourth, marked off by an 
oblique line from the supinator ridge to the dorsal border, the anconeus is inserted 
behind and internal to the supinator triangle. 
Below this a vertical ridge separates an inter- 
nal area, covered by the extensor carpi ulnaris, 
from an external area, for the origin of the ex- 
tensors of the thumb and index linger. 
The lower extremity is small, and presents 
(1) a rounded head with a flattened, semi- 
lunar articular facet interiorly, which plays 
upon the triangular fibro-cartilage, and a con- 
vex facet externally received into the sigmoid 
cavity of the radius; (2) the cylindrical styloid 
(“ pillar-like ”) process, which descends from 
the inner and back part of the head. To its 
extremity is attached the internal lateral liga- 
ment, and to the depression at its base, exter- 
nally, the triangular fibro-cartilage. In the 
groove behind and between it and the head 
glides the tendon of the extensor carpi ulnaris. 
The subcutaneous parts are the triangular 
surface back of the olecranon, the dorsal border, 
the lower fourth of the inner surface, the sty- 
loid, and, in pronation, the outer and fore part 
of the head. Notice that the ulna does not 
articulate directly with the carpus. 
Ossification occurs in cartilage from one 
primary centre for the shaft. The upper end 
of the olecranon, ossified from a secondary cen- 
tre, joins the shaft in the sixteenth or seven- 
teenth year. The lower extremity, ossifying 
from an earlier formed centre, joins the shaft 
from about the eighteenth to the twentieth year. 
POSTERIOR^ 
BORDER 
POSTERIOR 
BORDER 
STYLOIDi 
PROCESS^ 
|STY LOID 
(PROCESS 
THE RADIUS. 
Fig. 162.—-The bones of the right fore- 
arm, front view. (Testut.) 
The radius (“ spoke ”), the outer bone of the forearm, takes little part in the 
elbow-, but the principal part in the wrist-joint, articulating with the scaphoid, 
semilunar, and ulna below, the humerus and ulna above. 
The disc-shaped upper extremity, or head, presents, superiorly, a shallow articu- 
lar depression with an encircling rim, which articulate respectively with the capi- 
tellum of the humerus and the groove internal to it, especially in flexion of the 
elbow. Its smooth, short, vertical margin is deeper internally, where it articu- 
lates with the small sigmoid cavity of the ulna, than externally, where it is 
embraced by the orbicular ligament. Below the head is a constricted neck, which 
joins the shaft opposite the bicipital tuberosity. The latter, situated ventro- 
internally, has a rough dorsal portion for insertion of the biceps tendon and a 
smoother ventral part covered by a bursa. 
The shaft is triangular, curved outward and slightly backward, and becomes 
larger below. The internal or interosseous border, commencing below the tuber- 
osity, is prominent in the middle three-fifths, and in the lower fifth it divides into 
two lines, which pass to the two ends of the sigmoid cavity. The interosseous 
membrane is attached to it. The ventral and dorsal borders, commencing at the 
tuberosity, pass obliquely downward and outward as the ventral and dorsal oblique 
lines to the junction of the upper and middle thirds, and thence descend to the 
front and back of the styloid process, becoming less marked below. To the ventral 140 
THE BONES, 
oblique line the flexor sublimis digitorum is attached. The area between the two 
oblique lines, externally, gives insertion to the supinator as far down as the rough 
impression for the pronator radii teres, situated about the middle and at the most 
prominent part of the external surface. Below this the external surface is covered 
by the extensor tendons. The ventral surface gives origin in its upper two-thirds 
to the flexor longus pollicis, and its lower fourth gives insertion to the pronator 
quadratus. The nutrient foramen, directed upward, is seen above the middle of 
this surface. The dorsal surface in the middle third gives origin to the extensor 
ossis metacarpi pollicis above and to the extensor brevis pollicis below. Its 
lower third is covered by extensor tendons. 
The lower extremity is broad, thick, and quadrilateral. The large inferior or 
carped surface, concave and triangular, is divided by a ridge into an outer tri- 
angular surface, which articulates with the scaphoid, and an inner quadrilateral 
surface, which articulates with the semilunar. At the lower end of the inner 
surface is the narrow sigmoid cavity, concave from before backward, which articu- 
lates with the head of the ulna. It is at right angles to the carpal surface, and to 
the smooth margin between them is attached the base of the triangular fibro- 
cartilage. A transverse ridge at the lower end of the ventral surface limits the 
attachment of the pronator quadratus, and to it and the narrow space below it 
the anterior ligament of the wrist is attached. The outer or dorso-external sur- 
face is prolonged downward as the stout, pyramidal, subcutaneous styloid process. 
It is lower than the styloid process of the ulna, and is an important landmark in 
diagnosticating fractures. To its tip is attached the external lateral ligament, 
and to its base the brachio-radialis. . Two grooves, separated by a ridge, are seen 
on this surface; the ventral one gives passage to the tendons of the extensor 
ossis metacarpi pollicis and the extensor brevis pollicis ; the dorsal and inner one, 
sometimes subdivided by a low ridge, gives passage to the tendons of the 
extensores carpi radiales longus and brevis. The dorsal surface extends lower 
than the ventral, and of its two grooves the external narrow one for the extensor 
longus pollicis is separated from the last-mentioned groove by a prominent sub- 
cutaneous tubercle. The inner groove transmits the extensor communis digi- 
torum and the extensor indicis tendons. The posterior annular ligament converts 
these grooves into canals by its attachment to the dividing ridges, the styloid pro- 
cess, and the inner margin. 
The radius is more deeply placed than the ulna. In supination the two bones 
are parallel; in pronation the radius crosses the ulna. 
Ossification proceeds from one primary centre in the shaft, a secondary centre 
in the head, which joins the shaft in the seventeenth year, and a secondary centre 
in the lower extremity, which appears first, but does not ankylose with the shaft 
until the twentieth year. 
THE BONES OF THE HAND. 
The skeleton of the hand is composed of the bones of the carpus, of the meta- 
carpus, and the phalanges, forming the skeleton of the wrist, the palm, and the 
digits respectively. 
THE CARPAL BONES. 
The eight carpal bones (Figs. 163-165) are arranged in two rows of four each. 
The carpus is transversely convex dorsally, and concave on the palmar surface, 
on which, at the inner and outer extremities of each row, there is a prominence, 
attaching the anterior annular ligament, which completes a canal for the flexor 
tendons and the median nerve. The upper surface of the upper row is convex, 
articulating with the concavity of the radius and the triangular fibro-cartilage. 
The convexity extends on to the dorsal more than on to the palmar surface. In THE CARPAL BONES. 
141 
the line of articulation between the two rows the convexity of the os magnum and 
unciform is received into the concavity of the bones of the first row, and the 
convexity of the scaphoid is received into the slight concavity of the trapezium 
and trapezoid. The lower surface of the lower row is irregularly transverse 
and articulates with the metacarpus. In general the carpal bones are short 
Fig. 163.—The hones of the right carpus, the distal ends of the forearm hones, and the proximal ends of the 
metacarpal hones, ventral aspect. (Testut.) 
and irregularly cuboidal. The dorsal surfaces, usually the larger, and the pal- 
mar surfaces, more irregular, are rough for ligamentous attachments. As a rule, 
the upper and lower, outer and inner surfaces of these bones are articular to 
articulate with the bones above and below and on either side ; but a lateral sur- 
face of the terminal bones of each row is non-articular. Enumerated from the 
radial to the ulnar side, the upper row consists of the scaphoid, semilunar, cunei- 
form, and pisiform, and the lower row of the trapezium, trapezoid, os magnum, 
and unciform. The principal individual points of the separate bones are as 
follows : 
The Scaphoid. 
The scaphoid (“ boat-like ”), the largest bone of the upper row, is elongated 
downward and outward. Of the three articular surfaces, the upper is convex 
and triangular, articulating with the radius ; the lower is convex for the trapezium 
externally and the trapezoid internally ; and the internal is concave below for the 
os magnum, flat and crescentic above "for the semilunar. The outer end or surface 
is prolonged forward into a strong conical tuberosity, which attaches the annular 
ligament. The dorsal surface is a mere groove attaching the posterior ligaments 
of the wrist. 
The Semilunar. 
The semilunar (u half moon ”) presents four articular surfaces, of which the 
upper is convex for the radius; the lower is concave for the os magnum, and, 
near its inner margin, for the unciform ; the external is crescentic and narrow for 
the scaphoid ; and the internal is quadrilateral and larger for the cuneiform. 
The Cuneiform. 
The cuneiform (“wedge-shaped”) or 'pyramidal hone is placed with its blunted 
apex directed downward and inward. This bone also presents four articular 142 
THE BONES. 
RADIUS 
ulna! 
THIRD PHALANX^ 
Fig. 164.—The bones of the right hand, palmar aspect. (Modified from Testut.) THE CARPAL BONES. 
143 
facets. The base articulates with the semilunar. The upper surface is convex 
and smooth externally for the triangular fibro-cartilage, rough internally for liga- 
ments. The lower surface is concavo-convex for the unciform. On the palmar 
surface near the apex is a circular facet for the pisiform bone. The internal 
lateral ligament of the wrist is attached to the apex. 
The pisiform (“ pea-shaped ”) bone is vertically spheroidal, and has a single 
oval articular facet behind for the cuneiform. The rest of the bone projects for- 
ward as one of the internal eminences for the anterior annular ligament, and 
gives insertion to the flexor carpi ulnaris. The outer side is slightly concave. 
The Pisiform. 
The Trapezium. 
The trapezium (“ table ”), rhombic in form, is the most external bone of the 
lower row, and therefore has but three articular surfaces—a superior, slightly con- 
cave, for the scaphoid; an inferior, saddle-shaped, for the base of the first meta- 
carpal bone ; and an internal, divided by a ridge into an upper and larger for the 
trapezoid and a lower and smaller for the base of the second metacarpal bone. On 
the palmar surface there is a vertical groove for the passage of the flexor carpi 
radialis tendon, and external to this a ridge or tuberosity forming the second external 
prominence for the attachment of the anterior annular ligament. 
The Trapezoid. 
The trapezoid (“table-like”), the smallest bone of the lower row, has its 
longest diameter from before backward. Its dorsal surface is much larger than 
the palmar; its four articular surfaces are nearly continuous, and present supe- 
riorly a small, concave, triangular facet for the scaphoid; inferiorly, a long 
saddle-shaped facet for the second metacarpal bone; externally, a convex facet 
for the trapezium; and internally, a facet for the os magnum. 
The Os Magnum. 
The os magnum (“ great bone ”), the largest carpal bone, is elongated verti- 
cally, and occupies the centre of the wrist. It presents above a rounded head 
joined by a slightly constricted neck to a quadrilateral body below. It articulates 
above by its rounded head with the socket formed by the scaphoid and semilunar ; 
below, by three facets, of which the middle is the largest, with the second, third, 
and fourth metacarpal bones; externally, with the trapezoid by a small facet 
below that for the scaphoid; and internally, by an elongated facet, sometimes 
two facets, with the unciform. Its broad dorsal surface is larger than the palmar, 
and is prolonged downward and inward. 
The Unciform. 
The unciform (“ hook-shaped ”) is named from a large flattened hook-like pro- 
cess, concave externally, which projects forward from its palmar surface to attach 
at its apex the anterior annular ligament. Triangular in form, it articulates above 
by a narrow facet on its apex with the semilunar, below by two facets with the 
fourth and fifth metacarpal bones ; externally with the os magnum, and internally 
by a concavo-convex facet inclined upward, with the cuneiform, having but a 
narrow non-articular surface on the inner side. 
The carpal bones afford origin by their palmar surfaces to most of the short 
muscles of the thumb and little finger. 
Ossification occurs for each bone .from a single centre, which appears after 
birth. The cartilaginous os centrale, situated dorsally between the scaphoid, 144 
THE BONES. 
Os magnum, and trapezoid in the foetus, is occasionally ossified, but usually 
suppressed. 
THE METACARPAL BONES. 
The metacarpus (“beyond the carpus”) (Figs. 164, 165) contains five long 
bones, which support the fingers and form the skeleton of the palm. They 
diverge slightly from each other below, and, besides continuing the transverse 
arch of the carpus, they are slightly curved longitudinally, forming the hollow 
of the palm. They are numbered from without inward. The first is the broadest 
and shortest, the second the longest, and the rest decrease in length from the third 
to the fifth. 
General Characteristics.—The upjper end or base is irregularly cuboidal, and 
presents two non-articular, rough surfaces for ligamentous and muscular attach- 
ments, a broader dorsal and a narrower palmar surface ; and three articular 
surfaces, an upper for the carpus, and an inner and outer for articulation and 
ligamentous union with each other. The shaft is triangular and slightly curved, 
with its concavity in front. On the dorsal surface a ridge starts at the carpal 
end, and divides into two lines, each of which ends in a dorsal tubercle on the side 
of the head, the two enclosing a triangular surface covered by the extensor ten- 
dons. The dorsal surface on the sides of the ridge attaches the dorsal interossei 
muscles. The two lateral surfaces separated by a palmar ridge alford attachment 
to the palmar interossei muscles. The carpal end of the shaft is the most slender 
part. The shaft of the first metacarpal is broad and flattened, its dorsal surface 
is smooth, and its palmar aspect looks inward. The head presents for articulation 
with the first phalanx a rounded articular surface, broader and extending farthest 
on the palmar aspect, where it projects into two lateral cornua, or palmar tubercles, 
separated by a groove for the flexor tendons. The sides of the head are flattened, 
and marked by a depression for the lateral ligaments. The articular surface of 
the head of the first metacarpal bone is flatter than that of the others, and its two 
palmar tubercles are prominent for the two sesamoid bones in the flexor brevis 
pollicis tendons. 
Special Characteristics.—Besides those above given, these concern mainly the 
bases or carpal extremities. That of the first metacarpal has a saddle-shaped facet 
for the trapezium and no lateral facet, but a tubercle externally for the extensor 
ossis metacarpi pollicis. That of the second metacarpal has no external lateral 
facet, and three superior facets—a large, concave, central one for the trapezoid, 
and marginal ones for the os magnum and trapezium. Dorsally, near the external 
angle it has a tubercle for the extensor carpi radialis longus. That of the third 
has a prominent projection, the styloid process, at the outer and upper angle of 
the dorsum, below which the extensor carpi radialis brevis is inserted. That of 
the fourth has two facets externally, corresponding to two internally on the thirdr 
and, besides the main facet for the unciform above, there is a small facet for the 
os magnum on the outer angle dorsally. The base of the fifth has no facet inter- 
nally, but a tuberosity for the extensor carpi ulnaris. Its upper end is saddle- 
shaped and directed slightly outward. 
Ossification of the metacarpal bones and phalanges proceeds from one primary 
centre in the shaft, and a secondary centre in the base of the first metacarpal bone 
and of the phalanges and in the head of the other metacarpals. The secondary 
centre joins the shaft by the twentieth year. In the terminal phalanges the 
shaft centre begins in the distal end. 
THE PHALANGES. 
Of the fourteen phalanges (“ranks”) (Figs. 164, 165), each finger contains 
three and the thumb two. Like all long bones, they have two extremities and a 
shaft. The shafts, semi-cylindrical, are convex dorsally, and the rough margins 
of the flat palmar surfaces give attachment to the sheaths of the flexor tendons. THE BONES OF THE HAND. 
145 
RADI US 
U LNA 
IJthird phalanx 
Fig. 165.—The bones of the right hand, dorsal aspect. (After Testut.) 146 
THE BONES. 
The five of the first row are the longest, and are slightly curved longitudinally. 
The thicker upper end, or base, has a transversely elongated, concave articular 
facet (glenoid cavity), and the distal end, flattened from before backward, has a 
facet prolonged onto the palmar aspect, and divided into two condyles by a 
groove. The four of the second row, that of the thumb being wanting, are 
smaller, but similar, except that the proximal articular facet has a slight median 
ridge and two lateral depressions to fit the condyles of the first row. The five 
terminal or ungual (from unguis, “ a nail ”) phalanges have proximal extremities 
like those of the second row, with the addition of a palmar depression for the 
long flexor tendons. The shaft tapers to the flattened, expanded, horseshoe- 
shaped distal extremity, of which the smooth dorsal surface supports the nail, 
and the rough palmar surface the pulp of the finger. 
Taken together, the phalanges of the middle finger are the longest, and next 
those of the ring, index, little finger, and thumb, in the order named. 
THE BONES OF THE LOWER LIMB. 
The bony pelvis includes, besides the sacrum and coccyx, already described, 
the two hip-bones or the pelvic girdle. The skeleton of the lower limb comprises, 
besides the hip-bones, the femur in the thigh, the tibia and fibula in the leg, and 
the tarsal, metatarsal, and phalangeal bones in the foot. A large sesamoid bone, 
the patella, is found at the knee. 
THE HIP-BONE. 
The hip-bone, or os innominatum (“ unnamed bone”) (Figs. 166, 167), is 
irregular in form and shaped somewhat like the blade of a screw-propeller. It is 
narrowed in the middle, where the acetabulum, or socket for the femur, is seen ex- 
ternally, and expanded above and below. The large upper portion forms the false 
pelvis (“basin”), a part of the abdominal wall; the lower portion, perforated by 
the large thyroid (“shield-like”) or obturator (“ stopper ”) foramen, forms the 
lateral and front parts of the true pelvis, curving inward to meet its fellow. The 
hip-bone transmits the weight of the body to the femur. The three parts, ilium, 
ischium, and os pubis, separate in early life, ankylosed in the adult at the 
acetabulum, where they meet, are conveniently recognized as distinct in the 
description of the bone. In following the description hold the back of the coty- 
loid notch downward, in the natural position of the bone. 
The Ilium. 
The ilium (“ twisted ”) is the large, upper expanded portion, whose lower 
limit forms the upper two-fifths of the acetabulum, and whose upper border, the 
crest, presents three lips for attachment of the flat muscles of the abdomen. The 
crest is sinuous, irregularly thickened, and subcutaneous. 
To the outer lip are attached the tensor vagi me femoris in front, the obliquus 
externus in the ventral half, the latissimus in the dorsal half, and the gluteal 
portion of the fascia lata in the entire length; to the middle ridge, the obliquus 
internus in the ventral two-thirds ; to the inner lip, the transversalis in the ven- 
tral three-fourths, the quadratus lumborum and erector spinse behind, and the 
iliac fascia in the entire length. 
The crest ends in front in the prominent anterior superior spine, to which the 
inguinal (Poupart’s) ligament, the tensor vaginae femoris, and the sartorius are 
attached. The latter extends on to the notch below, which transmits the external 
cutaneous nerve, and separates the superior from the anterior inferior spine. From 
the latter, situated above the acetabulum, the straight tendon of the rectus femoris 
and the ilio-tibial band take origin. Below this spine and between it and the ilio- THE HIP-BONE. 
147 
pectineal eminence, where the ilium and os pubis meet, is seen the inferior iliac 
notch. This is situated in front of, and above, the acetabulum, and is traversed 
by the ilio-psoas muscle. 
The crest ends behind in the posterior superior spine, affording ligamentous 
attachment, separated by a slight notch from the posterior inferior spine, at the 
POSTERIOR SURE-. 
RIOR SPINE 
.ANTERIOR SUPE- 
RIOR SPINE 
POSTERIOR IN-, 
FERIOR SPINE 
jl ANTERIOR ,N" 
f FERIOR SPINE 
0. 
SPINE OF—r“ 
ISCHIUM V. 
SMALL SCIATIC" 
NOTCH / 
Fig. 166.—The right hip-bone, outer surface. (Testut.) 
lowest and hindermost point of the auricular articular surface. Below the spines 
is the great sacro-sciatic (“ sacro-ischiatic ”) notch, bounded above by the ilium, 
below and in front by the dorsal border of the ischium. 
The external surface, or dorsum, flat or convex in front and behind, concave in 
the middle, is marked by the superior, middle, and inferior gluteal lines, which 
form the lower limit of the origin of the glutei maximus, medius, and minimus 
respectively. The superior gluteal line begins at the crest about 2 inches in front 
of its dorsal end, and curves downward to the hind part of the great sciatic notch. 
To the lower part of the space behind it the pyriformis is often attached. The 
middle gluteal line curves backward and downward from the crest, 1 inch behind 
its anterior end, to the upper border of the great sciatic notch. The inferior 
gluteal line passes backward from just above the anterior inferior spine to the front 
of the great sciatic notch. Between the inferior gluteal line and the margin of 
the acetabulum, and a little behind the anterior inferior spine, is a rough surface 
for the reflected tendon of the rectus femoris. 
On the internal surface of the ilium is seen in front a smooth, concave, triangu- 
lar area, the iliac fossa, giving origin to the iliacus muscle, and behind a smaller, 
uneven surface. The latter is divided into an inferior auricular (ear-shaped) 
cartilage-covered surface for articulation with the sacrum, and a superior rough 
surface for the attachment of the posterior sacro-iliac ligaments below and the 
erector spinae above. The iliac fossa is limited below by the ilio-pectineal (“ilio- 
pubal ”) line, which forms the brim of the true pelvis, and extends between the 
auricular surface and the spine of the os pubis. Below the auricular surface and 
the dorsal end of the ilio-pectineal line is a small, smooth area of the ilium, which 
forms a small part of the wall of the true pelvis. 148 
THE BONES. 
The Ischium. 
The ischium (“ hip ”), situated dorso-inferiorly, forms superiorly the dorsal and 
lower two-fifths of the acetabulum and nearly all of its non-articular base; and 
below it terminates in the tuberosity. This is the thickest part of the bone, upon 
which the body rests in sitting, and from which the ramus (“branch”) ascends to 
join that of the os pubis to assist in bounding the obturator foramen. The trian- 
gular upper part, or body, presents externally, between the acetabular rim and the 
tuberosity, a groove for the upper border of the obturator externus. Internally it 
and the tuberosity form a flattened surface, which bounds the true pelvis laterally, 
and from which the obturator internus arises. Its dorso-internal border completes 
the great sacro-sciatic notch, which is limited below by the prominent spine of the 
ischium. To the spine the small sciatic ligament is attached behind, the coccygeus 
and levator ani internally, and the gemellus superior dorso-externally, where the 
spine is crossed by the internal pudic vessels and nerve. The cartilage-clad small 
sciatic notch, over which the obturator interims glides, separates the spine from the 
tuberosity below. The tuberosity presents behind a rough quadrate surface, from 
ILIAC 
FOSSA 
ANTERIOR SUPE- 
RIOR SPINE 
ANTERIOR IN-_ 
FERIOR SPINE 
-POSTERIOR SUPE- 
RIOR SPINE 
.POSTERIOR IN- 
FERIOR SPINE 
I LIO -P E CTI NEA L_ 
EMINENCE 
PUBIC, 
spine” 
CREST- 
-SPINE OF ISCHIUM 
ANGLE 
Fig. 167.—The right hip-bone, inner surface. (Testut.) 
the upper and outer portion of which the serai-membranosns arises, and from the 
lower and inner part the semi-tendinosus and biceps. This area is separated by a 
transverse ridge from a pyriform, rough surface in front of it, which is con- 
tinuous with the lower border of the ramus and attaches the adductor magnus. 
The sharp inner lip of the tuberosity attaches the falciform prolongation of the 
great sacro-sciatic ligament, and from the outer lip the quadratus femoris arises. 
The ramus, flattened like the descending ramus of the os pubis, with which it is 
continuous, presents a thin upper margin bounding the obturator foramen, and a 
thicker, everted, lower margin for ligamentous and muscular attachment. From 
its outer surface the obturator externus and adductor magnus arise, and from its 
inner surface arise the obturator internus, crus penis, erector penis, and, dorsally, 
the transversus perinei. THE OS PUBIS. 
149 
The Os Pubis. 
The ossa pubis (“bones of the pubic”) form the front wall of the pelvis. 
Each consists of a flat, quadrate body, situated internally and joined with the ilium 
and ischium, respectively, by two rami, the horizontal and descending. The ven- 
tral surface of the body and of the descending ramus, continuous with it, is rough 
for the origin of muscles. The corresponding dorsal or pelvic surface is smooth. 
From the ventral surface arise the obturator externus, the gracilis, and the three 
adductors ; from the dorsal surface, the obturator interims, levator ani, compressor 
urethrae, erector penis, and the crus penis. The inner border of the combined pubic 
and. ischiatic rami of the two sides, forming the pubic arch, is rough and more or 
less everted, especially in the female. The outer border of the body and descending 
ramus is narrow, and bounds the obturator foramen. The inner border of the pubic 
body presents an elongated, oval surface which is joined by cartilage to the oppo- 
site bone, forming the symphysis pubis. The broad, rough upper border or pubic 
crest stretches from the upper end of the symphysis, the angle, outward to the 
prominent spine of the os pubis. To the crest are attached the rectus abdominis 
and pyramidalis and the conjoined tendon; to the spine, the inguinal (Poupart’s) 
ligament. The horizontal ramus extends from the body to the ilium at the ilio- 
pectineal eminence, and expands at its outer end to form the ventral fifth of the 
acetabulum. More or less triangular on section, its upper border is the pubic 
portion of the ilio-pectineal line, to which Gimbernat’s ligament and a part of the 
conjoined tendon are attached internally. The triangular surface in front of this 
line gives origin to the pectineus, and is bounded below by the prominent obturator 
crest, which extends from the pubic spine to the cotyloid notch. The under sur- 
face bounds the obturator foramen superiorly, 
and presents externally the deep oblique obturator 
groove for the obturator vessels and nerve. 
The acetabulum (“ small cup ”), or cotyloid 
cavity, is a nearly hemispherical cavity which 
looks outward, downward, and forward. It 
consists of a horseshoe-shaped marginal artic- 
ular portion, which lodges the femoral head, 
and a central and inferior depressed, non-artic- 
ular portion, which lodges a mass of fat. The 
upper part of the margin is the stoutest and 
most prominent; the lower part is deficient 
close to the obturator foramen, forming the 
cotyloid notch, which is bridged across by the 
transverse ligament, forming the cotyloid fora- 
men for the passage of a nerve and vessels into 
the joint and to the head of the femur. To 
the margin of the articular portion the cotyloid 
ligament is attached, deepening the cavity so as 
to be more than a hemisphere, and outside of this the capsular ligament arises. 
The obturator or thyroid, foramen, below and internal to the acetabulum, is 
formed by and situated between the ischium and os pubis. It is closed by the 
fibrous obturator membrane, which is attached to its margins except near the 
groove for the obturator vessels and fierce, in its upper margin. In the female it 
is broad and triangular, in the male oval and elongated downward and backward. 
The iliac crest, pubic spine, tuberosity of the ischium, and combined rami 
of the os pubis and ischium (bounding the perineum) can be felt subcutaneously. 
The anterior superior iliac spine and the pubic spine are of great importance as 
landmarks. The hip-bone is much thickened along the lines of greatest pressure 
—i. e., between the auricular surface and the upper part of the acetabulum and 
tuberosity of the ischium. There is a thick ridge running from the acetabulum 
to the crest, but the centres of the iliac fossa and of the acetabulum are both thin. 
Fig. 168.—Development of the hip-bone, 
showing the union of the three portions in 
the acetabulum. (Testut.) 150 
THE BONES. 
Ossification (Fig. 168) takes place in cartilage from a centre for each of the 
three parts, ilium, ischium, and os pubis. A secondary centre appears later in 
the Y-shaped cartilage, where they meet in the acetabulum. This fuses with and 
joins together the three parts from the sixteenth to the twentieth year. Secondary 
nuclei appear for the iliac crest, the anterior inferior spine, the ischial tuberosity, 
and the pubic crest from the fifteenth year on, and unite with the main bone 
about the twentieth year. 
The pelvis (Figs. 169, 170), whose constituent parts, the two hip-bones, con- 
nected behind by the sacrum and coccyx, have already been described, is divided 
into two parts by a plane passing through the sacral promontory behind, the ilio- 
pectineal lines laterally, and the pubic crests in front. The part above this 
plane, composed of the ilia, belongs to the abdominal cavity, but is called the 
false pelvis. The limiting line is called the brim, and the included heart-shaped 
space the inlet of the lower part, or true pelvis. The outlet, or lower circum- 
THE PELVIS. 
Fig. 169.—The planes of the pelvis. (Testut.) 
ference of the pelvic cavity, presents three prominences—the ischial tuberosities 
laterally and the coccyx behind—separated by three notches, the pubic arch in 
front and the two sciatic notches behind. The pubic arch is the angular space 
in front beneath the symphysis and bounded by the combined rami of the ischia 
and ossa pubis. The sciatic notches are bridged across and converted into fora- 
mina by the sacro-sciatic ligaments, which bound the outlet of the pelvis as well 
as the perineum dorso-laterally. 
The cavity of the pelvis is shallow (1-|—2 inches) in front, where it is bounded 
by the os pubis, and deepest (5-5-1- inches) behind, where the curved sacrum and 
coccyx form its bony wall. The ischia form the lateral walls. The axis of the 
pelvis, or the line drawn through the centres of the planes of the inlet, cavity, 
and outlet of the pelvis, is curved with its concavity forward. 
The position of the pelvis in the erect attitude of the body is so tilted or 
inclined that the plane of the inlet forms an angle of 50° to 60° with the hori- 
zon, so that a line drawn at right angles to the centre of the plane of the 
inlet, if prolonged upward, would about meet the umbilicus. Furthermore, the 
base of the sacrum is raised about inches above the upper margin of the 
symphysis pubis, and the tip of the coccyx is \-l inch above the lower end of 
the symphysis. The plane of the outlet is more nearly horizontal, forming an THE FEMUR. 
151 
angle of about 15° with the horizon. This tilting of the pelvis brings the sacrum 
more or less on top, where, however, it does not form the keystone of the arch, 
for its widest aspect looks downward into the pelvis; and the bone is held in 
place mainly by the strong posterior sacro-iliac ligaments, and only slightly by 
the projection of the lower and ventral margins of the ilio-auricular surfaces. The 
weight of the body is transmitted from the sacro-iliac joint in an arch along the 
massive ilio-pectineal line to the acetabulum in the standing position, and to the 
ischial tuberosities in the sitting posture. The horizontal rami of the ossa pubis 
Fig. 170.—The female pelvis, rear view. (Testut.) 
form the counter-arches or ties to the former arch, the combined ischial and 
pubic rami to the latter arch. The pressure along the arches and counter-arches 
when the bones are softened by rickets or osteomalacia causes various deformities 
of the pelvis. 
Sex differences relate to both size and form. In the female the bones are 
lighter and smoother. The cavity is broader, more capacious, and less deep. 
The symphysis is not so deep, the pubic arch wider, the ischial tuberosities more 
expanded, and the sacrum flatter and broader. - The sacral promontory is less 
projecting, giving the pelvic inlet a more oval shape. The thyroid foramina aie 
more triangular. The differences of sex are noticeable in early life ; but in gen- 
eral all pelves are more or less of the male type until about puberty, when the 
female characteristics become marked. # . 
The following table represents the average measurements of the pelvis m 
inches : 
Diameters. 
Male. 
Female. 
Brim. 
Cavity. 
Outlet. 
Brim. 
Cavity. 
Outlet. 
5 
4f 
5 
4f 
4 
4y 
H 
4i 
5 
4? 
Oblique (from the sacro-iliac joint to the ilio-pectmeal 
4f 
H 
4 
5 
THE FEMUR. 
The femur (Figs. 171, 172), the largest and longest bone in the body, is 
inclined inward and slightly backward, so as to approach its fellow infenorly. it 
extends between and articulates with the hip-bone above and the tibia below. 
The upper extremity includes the head, the neck, and the two trochanters, 152 
THE BONES. 
which attach the rotator muscles. The neck extends inward, upward, and slightly 
forward from the shaft to the head. It is compressed from before backward, but 
vertically expanded, especially where it joins the shaft. Its length is greater 
behind and below, and it is concave behind. Its axis forms an angle of 125° 
with that of the shaft. At birth this angle averages 160°. During growth, 
owing to the weight of the body, it decreases to from 140° to 110° ; but after 
growth is completed it remains fixed. It is less in females and short subjects. 
SMALL TRO- 
CHANTER 
SMALL TRO- 
CHANTER 
Fig. 171.—The right femur, front view. (Testut.) 
Fig. 172.—The right femur, rear view. (Testut.) 
The head is received into the acetabulum of the hip-bone. It forms more than 
half a sphere, and is covered with cartilage, except at a small pit behind and 
below the centre, to the upper half of which the ligamentum teres is attached. At 
the junction of the neck and shaft the two trochanters project. The great tro- 
chanter is a stout, quadrilateral plate, continuous with the outer surface of the 
shaft, which reaches nearly to the highest level of the neck. On its outer surface 
the gluteus medius is attached to an oblique line extending downward and forward THE FEMUR. 
153 
from its dorso-superior angle. The lower limit of this surface and the upper 
extent of the vastus externus are marked by a horizontal line, which, in front of 
the trochanter, ascends to an eminence, the tubercle, at the junction of the tro- 
chanter with the neck. Internal to the trochanter and between it and the neck is 
the deep digital or trochanteric fossa, which receives the tendon of the obturator 
externus. Above and in front of this fossa the obturator internus and the gemelli 
are attached. Behind the latter the pyriformis is attached to the narrow free 
upper border. The gluteus minimus is inserted upon the anterior border, while 
the thick, rounded posterior border is continuous with the posterior intertrochanteric 
line, which runs downward and inward to the small trochanter and limits the neck 
behind. The small trochanter, receiving the insertion of the ilio-psoas, projects as 
a pyramidal eminence from the dorso-internal aspect, where the lower end of 
the neck joins the shaft. The anterior intertrochanteric line limits the neck in 
front, and attaches the thickened front part of the capsular ligament. It is the 
upper part of the spiral line, which runs from the tubercle of the femur down- 
ward and inward to the linea aspera, passing a little in front of the small tro- 
chanter. 
The shaft, arched convexly forward, is nearly cylindrical, except for a flattening 
in front and a prominent buttress-ridge, the linea aspera (“ rough line”) behind; 
so that three rather indistinct surfaces, a ventral and two lateral, may be dis- 
tinguished, which are covered by the three vasti muscles. The shaft expands as 
it approaches the lower extremity. The linea aspera, presents in the central third 
two lips and a rough, narrow interval often called the middle lip. In the upper 
third the external lip extends up to the great trochanter as the prominent gluteal 
ridge for the gluteus maximus. _ The internal lip is continuous with the spiral 
line, while a third line, giving insertion to the pectineus, ascends to the small 
trochanter from the intermediate space. Inferiorly the two lips diverge, and 
extend to the condyles as the external and internal condylar ridges, enclosing a fiat 
triangular area, the floor of the upper part of the popliteal space. The inner 
ridge is interrupted by the crossing of the femoral vessels in the upper part, and 
ends below in the sharp adductor tubercle, to which the lowest fibres of the 
adductor magnus are attached. The canal of the nutrient artery is directed upward 
in the linea aspera a little above its centre. The following muscles, besides those 
already mentioned, are attached to the linea aspera and its prolongations ; To the 
inner lip is attached the vastus internus, and to its lower two-thirds the adduc- 
tor longus ; to the outer lip the vastus externus ; and to its lower two-thirds and 
the external condylar ridge the short head of the biceps. The adductor magnus 
is inserted below into the inner condylar ridge and the adductor tubercle, above, 
just internal to the gluteal ridge, as far as the quadratus femoris, and in the mid- 
dle third to the intermediate space. The adductor brevis is attached to the upper 
third of the intermediate space below and external to the pectineus. A faint line, 
the linea quadrati, for insertion of the quadratus femoris, is sometimes visible, and 
passes upward from the outer side of the small trochanter to the middle of the 
posterior intertrochanteric line, where the tubercle of the quadratus is sometimes 
seen. Part of the iliacus is attached to an area below the small trochanter, inter- 
nal to the pectineus. 
The lower extremity presents two condyles, external and internal, most promi- 
nent behind, where they are separated by the deep intercondylar notch, while in 
front they are united by the trochlear (articular) surface for the patella. The pait 
of the trochlea external to its vertical groove is the larger, and isvery prominent 
along its outer edge, serving to resist the tendency to outward dislocation of tic 
patella. Continuous with the trochlea are the ‘ cartilage-clad lower and dor- 
sal surfaces of the condyles, which, though of different curvatures in different 
parts, articulate with the tibia. The external condyle is the broader, the internal 
the narrower and the more prominent laterally and behind, while in front it en s 
outward to the patellar surface. In the natural or oblique position of the bone 
the lower surfaces of the two condyles are in the same plane; but if held verti- 154 
THE BONES. 
cally the inner is the lower. On the lateral surface of each condyle the cor- 
responding lateral ligament of the knee-joint is attached to a rough tuberosity. 
Below the outer tuberosity the popliteus arises from a depression, from which a 
groove passing backward and upward is occupied by the tendon of the muscle in 
flexion of the knee. To the mesial surfaces bounding the intercondylar notch the 
crucial ligaments are attached, the anterior to the external condyle behind, the 
posterior to the internal condyle in front. Immediately above and behind con- 
dyles the two heads of the gastrocnemius muscle arise, and above its outer head 
is the origin of the plantaris. 
The great trochanter, the two condyles, and, during flexion, the trochlear 
surface for the patella, are the only subcutaneous parts of the bone. The great 
trochanter is an important landmark. 
The femur averages 18 inches in length in the European male, and 17 inches in 
the female. It is inclined inward at an angle of about 9° with the sagittal plane 
in the male, and at a greater angle in the female. The femur presents an angle 
of torsion between the upper and lower extremities, but in the opposite direction 
to that of the humerus, and ranging between 5° and 20°. The lamellae of the 
cancellous tissue at the upper extremity are arranged in arches, which cross one 
another and strengthen the neck of the bone, through which the weight of the 
body is transmitted from the head to the shaft. A nearly vertical plane of com- 
pact bone (calcar femorale, “ femoral spur ”) projects into the interior, toward the 
great trochanter, from a little in front of the small trochanter, and strengthens 
the concave side of the neck. It is liable to absorption in old age. The de- 
pression for the ligamentum teres is wanting in a small proportion of cases, and 
in a still smaller number is replaced by a tubercle. The gluteal ridge is some- 
times so prominent as to be called the third trochanter. 
Ossification occurs in the shaft from one centre, which appears very early. 
The lower epiphysis appears as a single centre. One after another centre appears 
for the head, great and small trochanters. These join the shaft as follows ; small 
trochanter, seventeenth year; great trochanter, eighteenth year ; head, nineteenth 
year; condyles, twentieth to twenty-first year. The neck is an outgrowth from 
the shaft. The line of fusion of the condylar epiphysis with the shaft is below 
the adductor tubercle and the origins of the gastrocnemius muscle. 
THE PATELLA. 
The patella (“ little dish ”), or knee-pan (Figs. 173, 174), is a flattened, triangu- 
lar sesamoid bone in the quadriceps extensor tendon at the front of the knee-joint. 
BASE 
BASE 
OUTER 1 
BORDER ' 
INNER 
BORDER 
INNER ... 
BORDER 
OUTER 
“"border 
APEX 
APEX 
Fig. 173.—The right patella, ventral surface. 
(Testut.) 
Fig. 174.—The right patella, dorsal surface. 
(Testut.) 
Its slightly convex ventral surface is longitudinally striated for the fibrous expan- 
sion of the tendon. Its dorsal surface is mostly cartilage-clad to articulate with 
the trochlear surface of the femur, and is divided by a vertical ridge into a larger 
outer, concave portion and a smaller inner, convex one, to articulate with the THE {TIBIA. 
155 
outer and inner sides respectively of the trochlear surface. The upper border, or 
base, is bevelled in front, and attaches the tendons of the muscles composing the 
quadriceps extensor. The apex, directed 
downward, and the border on either side of 
it attach the ligamentum patellae, while the 
rough area of the dorsal surface above the 
apex is in relation to a mass of fat. In 
front of the patella is a bursa separating it 
from the skin. The entire articular surface 
is not in contact with the femur at any time, 
but one part after another as the knee is 
moved. 
The patella is liable to transverse frac- 
ture from muscular action, and, as its blood- 
supply conies largely from above, care should 
be taken in dealing with the upper fragment not to strangulate it. 
Fig. 175.—The upper surface of the right 
tibia. (Testut.) 
THE TIBIA 
The tibia (“ shin ”) (Figs. 175—177) 
is the inner, larger, and more forward 
of the bones of the leg, and conveys the 
weight of the body from the femur to 
the astragalus. 
The upper extremity, or head, is thick 
and inclined slightly backward. It is 
expanded on each side into a massive 
tuberosity, whose upper aspect presents a 
slightly concave articular surface, which 
receives the condyles of the femur. Of 
these articular surfaces, the inner is 
longer from before backward and more 
concave ; the outer is smaller, flatter, and 
more circular. Both are flattened per- 
ipherally, where the semilunar fibro- 
cartilages rest upon them and deepen 
the socket for the femoral condyles. 
Projecting upward, between these sur- 
faces, is the spine of the tibia, which is 
laterally bifid. To rough depressions 
between the articular surfaces are at- 
tached in front of the spine the anterior 
crucial ligament, with the forward ex- 
tremities of the semilunar cartilages, 
and behind the spine the posterior cru- 
cial ligament with the hind extremities 
of the semilunar cartilages. The de- 
pression behind the spine is continued 
backward into a notch, the popliteal 
notch, which separates the tuberosities 
posteriorly. In front the tuberosities 
are continuous, and form on the anterior 
surface of the head a triangle whose 
apex points downward and ends at the 
tubercle, the lower end of which attaches 
the ligamentum patellae, its upper smooth 
SPINE 
OUTER 
BEROSITY i 
STYLOID. /H 
PROCESSTjX 
||NNER TU- 
f BEROSITY 
-ANTERIOR 
BORDER 
ANTERO-EXTEH- 
NAL BORDER 
ANTERO-INTER- 
NAL BORDER 
OUTER 
MALLEOLUS 
INNER 
MALLEOLUS 
Fig. 176.—The right tibia and fibula in their nor- 
nal relations, front view. (Modified from Testut.) 
part being separated from the ligament by a bursa. Upon it the body rests in 156 
THE BONES. 
kneeling. At the outer angle of this triangular surface is a prominence to 
which the ilio-tibial band of the fascia lata is attached. The larger, internal 
tuberosity is marked behind by a horizontal groove for the insertion of the semi- 
membranosus tendon, and the external tuberosity presents postero-externally a 
rounded articular facet for the head of the fibula. 
The three-sided shaft of the tibia is very thick above and tapers toward the 
lower end, where it again expands slightly. The internal surface is convex and 
subcutaneous, except at the upper end, where, internal to the tubercle, the sar- 
torius, gracilis, and semi-tendinosus tendons are attached. The external surface 
is concave in its upper two-thirds, where 
it gives origin to the tibialis anterior, 
convex below, where it looks more for- 
ward and is covered by the extensor 
tendons. On the posterior surface the 
popliteus is inserted on a triangular area 
at the upper end, limited below by the 
oblique line, which passes from the fibular 
facet downward and inward to the in- 
ternal border, and attaches the soleus 
muscle. Below the oblique line this 
surface is divided by a longitudinal 
ridge into an inner portion giving origin 
to the flexor longns digitorum, and an 
outer for the tibialis posterior. At the 
upper part of this surface and below the 
oblique line is found the large foramen 
for the nutrient artery, directed down- 
ward. The anterior border, or shin, 
commencing above, just below the 
tubercle, is subcutaneous, sinuous, and 
sharp in its upper two-thirds, rounded in 
its lower third, where it passes to the 
front of the internal malleolus. The 
external or interosseus border attaches the 
interosseous membrane and bifurcates 
near the lower end, thus enclosing a 
triangular area for the inferior interos- 
seous ligament. The internal border 
extends from the back of the internal 
tuberosity above to the back of the in- 
ternal malleolus below. The internal 
lateral ligament is attached to its upper 
3 inches, the soleus muscle to its middle 
third. 
SPINE 
OUTER 
TUBEROSITY 
INNER TUV 
BEROSITY " 
STYLOID 
PROCESS 
_POSTERO-EX- 
JTERNAL BORDER 
INNER 
MALLEOLUS*" 
I OUTER 
SfMALLEOLUS 
GROOVE FOR 
? PERONEI 
The lower extremity is somewhat quad- 
rilateral, and is expanded transversely. 
It is prolonged downward, internally, as 
a flattish, subcutaneous process, the in- 
ternal malleolus, from the tip and mar- 
gins of which the internal lateral liga- 
ment of the ankle arises. The fore part 
GROOVE FOR FLEX. LONG. DIGIT. 
GROOVE FOR FLEX. 
LONG, HALL. 
Fig. 177.—The right tibia and fibula in their nor- 
mal relations, rear view. (Testut.) 
GROOVE FOR TIBIALIS POST. 
of its external surface is articular, for the inner lateral facet of the astragalus, 
and is continuous with the inferior quadrilateral articular surface of the extremity, 
which articulates with the upper surface of the astragalus. This inferior facet is 
concave from before backward, and is narrower, and descends lower behind than 
in front. Behind the malleolus is a groove for the tibialis posterior and the flexor 
longus digitorum, while farther externally the flexor longus pollicis slightly THE FIBULA. 
157 
grooves the posterior border. The external surface of the lower extremity of the 
bone, except for a narrow articular border below, is rough for ligaments which 
attach it to the fibula. 
The tibia is twisted, so that when the axis of the upper end is transverse that 
of the lower end is inclined from without inward and forward at an angle aver- 
aging s°—2o°, but sometimes varying between 0° and 48°. 
Ossification.—Each epiphysis ossifies from a single centre. That in the upper 
end includes the tubercle and appears first. The lower end unites with the shaft 
at the eighteenth or nineteenth year, the upper end in the twenty-first or twenty- 
second year. 
THE FIBULA. 
The fibula (“ clasp” or “brace”) (Figs. 176, 177) is the slender outer bone 
of the leg. It reaches lower than, but not as high as, the tibia. Its upper end 
is behind the plane of the lower end, and its shaft is slightly curved and very 
variable in its contour. (The Greek name of this bone is perone, the adjective 
from which (“ peroneal ”) is synonymous with “ fibular.”) 
The upper extremity or head is irregularly expanded, and presents above and 
internally a small obliquely placed articular facet, looking upward, inward, and 
forward, articulating with the facet on the outer tuberosity of the tibia. Behind 
and slightly external to the facet rises a conical eminence, the styloid process, to 
which the short external lateral ligament of the knee is attached, while to a slight 
depression in front of and external to it are attached the external lateral ligament 
and the tendon of the biceps. 
The lower extremity is a thick pyramidal process which forms the external mal- 
leolus (“ little hammer ”). The latter is lower, more posterior, and more promi- 
nent than the internal malleolus. Its inner surfia.ee presents in front a triangular 
facet for articulation with the outer facet on the astragalus, above which is a rough 
triangular surface for the inferior interosseous ligament. Behind the facet is a 
rough depression for the attachment and reception of the hind fasciculus of the 
external lateral ligament of the ankle. The posterior surface is grooved for the 
peronei longus and brevis. The external surface is subcutaneous and continuous 
with a subcutaneous triangular surface tapering upward for two or three inches 
upon the shaft. 
The shaft has four variable surfaces, each giving origin to a muscle or a group 
of muscles which produce a particular motion of the foot. The four borders 
limiting these surfaces attach fibrous septa separating the muscles or muscle- 
groups. The lower fourth of the shaft is twisted outward. The well-marked 
antero-external border begins in front ot the head, and bifurcates in the lower 
-ANTERIOR BORDER 
INTERNAL BORDER- 
EXTERNAL BORDER 
TIBIA 
-ANT.-EXT. BORDER 
ANT.-INT. BORDER- 
POST.* 1 NT, BORDER— 
-POST.-EXT. BORDER 
FIBULA 
Ftp 178 -Horizontal section of the bones of the leg at the junction of the upper and middle thirds, show- 
ing their bordersand s JrfecS and the relations of the interosseous membrane. (Testut.) 
fourth to include the triangular subcutaneous surface above mentioned. To it is 
attached the anterior tibial fascia which separates the peronei longus and brevis, 
which pronate the foot and occupy the external or pronator surface tromi me 
extensores longus digitorum and propnus hallucis and the peroneus tertius, wlncn 158 
THE BONES. 
arise from the narrow anterior or flexor surface, and flex the ankle on continuing 
their primary action. The external surface turns dorsally in the lower fourth to 
become continuous with the posterior surface of the malleolus. The antero-inter- 
nal or interosseous border (Fig. 178) is close to the antero-external border above 
but diverges from it below, where, an inch or more above the malleolus, it ends 
at the apex of a rough triangular area which attaches the inferior interosseous 
ligament. This border attaches the interosseous membrane which separates the 
muscles arising from the anterior surface from the tibialis posterior, which supi- 
nates the ankle and arises from the fusiform internal or supinator surface. The 
latter surface occupies the upper two-thirds only of the shaft. It is separated 
from the posterior surface by the postero-internal border, which joins the interos- 
seous border in the lower third, and attaches a fibrous septum separating the 
muscles which arise from the surfaces on either side. The posterior or extensor 
surface, becoming more internal below, attaches the solcus above and the flexor 
longus hallucis below. The latter muscles are separated from the peronei by a 
septum attached to the prominent postero-external border, which passes from the 
styloid process to the back of the malleolus. The nutrient foramen, directed 
downward, is seen in the middle third of the posterior surface. 
The head, the outer surface of the malleolus, and the triangular area above it 
are subcutaneous; Otherwise the shaft is covered by muscles. Fracture occurs 
very commonly an inch or two above the malleolus. 
Ossification.—The lower epiphysis, although it ossifies first, joins the shaft 
about the twentieth or twenty-first year, while the upper or more vestigial 
epiphysis remains separate until the twenty-second to the twenty-fourth year. 
THE BONES OF THE FOOT. 
The skeleton of the foot is composed of three groups of bones—those of the 
tarsus (“the flat of the foot”), metatarsus (“beyond the tarsus”), and digits. The 
bones of the foot, although resembling those of the hand, are modified in the direc- 
tion of greater firmness, and are in a position of permanent pronation and dorsal 
flexion. 
THE TARSAL BONES. 
The tarsus contains seven bones—the astragalus, calcaneum, cuboid, navicular, 
and the three cuneiform bones. 
The Astragalus. 
The astragalus (“a die”), or talus (Figs. 179, 181, 183, 184), occupies the 
upper part of the arch of the foot, where it articu- 
lates with the tibia above and internally, and with 
the fibula externally. It receives the weight of the 
body from the tibia, and transmits it by articulation 
to the calcaneum below and the navicular in front. 
Its long axis is directed forward and inward to the 
convex anterior extremity, or head, which is joined 
by a slightly constricted nech to the main part, or body, 
behind. The upper surf ace is occupied by the trochlear 
articular surface for the tibia. This is convex from 
before backward, and slightly concave transversely. 
It is broader in front than behind, and continuous 
with the lateral facets for the malleoli. The facet 
on the outer surface, for the external malleolus, is 
triangular and vertically concave ; that on the inner 
surface, for the internal malleolus, is smaller, nar- 
row, and pyriform ; and to the rough surface below 
GROOVE FOR FLEX* 
LONG. HALU /M 
Fig. 179.—Eight astragalus, under 
surface. (Testut.) 
is attached the deep portion of the deltoid ligament. The under surface presents 
a deep groove for the interosseous ligament, which passes from within obliquely THE CUBOID. 
159 
outward and forward to the neck, and separates the two facets which articulate 
with the calcaneum. The posterior facet is concave from behind forward; the 
anterior is convex and rests upon the facet on the sustentaculum tali of the os 
calcis. The anterior facet is continuous in front with the oval facet on the head, 
for the navicular, though there intervenes between them internally a small facet 
which rests upon the inferior calcaneo-scaphoid ligament. The posterior surface 
is a mere narrow border, grooved internally for the flexor longus hallucis. The 
tubercle bounding this groove externally attaches the posterior band of the exter- 
nal lateral ligament of the ankle, and sometimes is found as a separate bone, the 
os trigonum (“ triangular bone ”). 
The calcaneum (“heel”) or os colds (Figs. 180-183), the largest bone of the 
foot, projects backward and downward to form the heel, which acts as a fulcrum 
for the calf-muscles, and transmits 
most of the weight of the body to the 
ground. Its long axis is directed for- 
ward and a little outward from its en- 
larged posterior extremity. 
The upper surface presents in its 
fore part two facets for articulation 
with the astragalus. The larger, 
hinder, and external facet is convex 
from before backward; the forward 
one is long, concave, often subdivided, 
and is located on the upper surface of 
the sustentaculum tali (a support of the 
astragalus ”), a flat, shelf-like process projecting inward on a level with the upper 
surface. Between these two facets is a groove for the interosseous ligament, 
passing obliquely forward and outward to a rough surface where the extensor 
brevis digitorum arises. The under surface is narrow, rough, and transversely 
convex. It ends behind in two tubercles, which attach plantar muscles and the 
plantar fascia. The inner tubercle is the larger, the outer the more prominent. 
In front of these the long plantar ligament is attached while the short plantar 
ligament is attached to the anterior tubercle at the fore end of this surface and to 
the shallow groove in front of it. The inner surface presents a concavity between 
the inner tubercle behind and the sustentaculum tali in front. The under sur- 
face of the latter presents a groove continuous with that at the back of the 
astragalus for the flexor longus hallucis. The outer surface, rough, flat, and 
subcutaneous, presents at its fore part two slight grooves, the upper*for the 
peroneus brevis, the lower for the peroneus longus, separated by a ridge or 
tubercle, the peroneal spine. The posterior surface is smooth above, and separated 
by a bursa from the tendo-calcaneus (Achillis), which is attached below. On the 
anterior surface is a saddle-shaped articular facet for the cuboid. 
The calcaneum and astragalus are both very vascular. The veins of the 
former emerge mostly on the inner side, where they are less exposed to pressure. 
The Calcaneum. 
Tig. 180. Right calcaneum, internal surface. (Testut.) 
The Cuboid. 
The cuboid (“cube-like”) (Figs. 181-183) lies on the outer side of the foot, 
between the calcaneum behind and the fourth and fifth metatarsals in front. 
Although cuboidal, the four surfaces adjoining the external converge to it, 
giving the bone a pyramidal shape. Posteriorly, it articulates with the calca- 
neum by a saddle-shaped facet prolonged backward at the lower and inter- 
nal angle, beneath the calcaneum. Anteriorly, a smaller facet is divided into 
an outer triangular and an inner quadrilateral portion for the fifth and fourt 160 
THE BONES. 
metatarsal bones respectively. The upper surface, directed somewhat out- 
ward, is hat and non-articular. The loioer surface presents a prominent ridge 
or tuberosity, directed obliquely inward 
and forward, in front of which is a 
deep groove for the peroneus longus. 
To the ridge and the triangular surface 
behind it are attached the plantar liga- 
ments. On the narrow external surface 
or border the outer end of the ridge is 
usually facetted for the bend in the 
peroneus longus tendon. The internal 
surface presents near its middle and 
upper part a facet for the external cunei- 
form, and oftentimes behind this a second 
facet for the navicular, while the rest of 
the surface is rough for interosseous 
ligaments. 
The Navicular. 
The navicular (“boat-shaped”) or 
scaphoid hone (Figs. 181-184), situated on 
the inner side of the foot between the as- 
tragalus and the cuneiform bones, is com- 
pressed from before backward. Proxi- 
mally its concavity articulates with the 
head of the astragalus. Its convex dis- 
tal surface is subdivided into three tri- 
angular facets for the cuneiform bones. 
Above it is rough and convex, below 
more narrow and uneven, externally 
rough for ligaments, with an inconstant 
facet for the cuboid. Internally it is 
prolonged downward and inward into 
the prominent navicular tuberosity, which 
attaches part of the tibialis posterior, 
and, being subcutaneous, is an important 
landmark in finding the medio-tarsal 
(Chopart’s) joint. 
The Cuneiform. 
The three cuneiform hones, named re- 
spectively from their position from with- 
in outward, interned, middle, and external, 
are wedge-shaped, and lie between the 
navicular and the three inner metatarsal 
bones. Their proximal surfaces, articu- 
lating with the navicular, are concave 
and in the same transverse line ; their 
distal surfaces, articulating with the 
three inner metatarsals, are convex or 
flat, and the middle cuneiform being the 
Fig. 181.—The hones of the right foot, viewed 
from above. (Testut.) 
shortest, a deep recess is formed, into which the base of the second matatarsal is 
received. 
The Internal Cuneiform. 
The internal cuneiform (Figs. 181,182,184), the largest of the three, has the base 
of the wedge directed downward on the inner border of the foot. The distal. THE METATARSAL BONES. 
161 
kidney-shaped facet for the base of the first metatarsal is much larger than the 
proximal pyriform facet for the navicular. On the internal surface is an oblique 
shallow groove for the tibialis anterior tendon, leading to an oval facet antero- 
inferiorly where the tendon is in part attached. On the rough, concave exter- 
nal surface there is an L-shaped facet along the upper and hind borders, which 
articulates with the middle cuneiform, except in front, where a distinct facet is 
marked off for the inner side of the base of the second metatarsal bone. 
The Middle Cuneiform. 
The middle cuneiform (Figs. 181-183), the smallest of the three, has its base 
directed upward. The facets in front and behind are wedge-shaped, that in front 
for the second metatarsal being slightly smaller. On the inner surface is an L- 
shaped facet along its upper and hind borders corresponding with that on the 
internal cuneiform. On the outer surface a facet along its hind border articu- 
lates with the external cuneiform. 
The External Cuneiform. 
The external cuneiform (Figs. 181-183) also has its base directed upward. 
Continuous with the triangular facet for the base of the third metatarsal, at 
the fore part of each lateral surface, are small facets, internally for the second 
metatarsal and externally for the fourth metatarsal. The internal surface has in 
addition a facet along its hind border for the middle cuneiform, and the external 
surface has a larger facet behind and above for the cuboid. 
The Metatarsal Bones. 
The five metatarsal bones (Figs. 181-184) are numbered from within outward. 
They closely resemble the metacarpal bones in having irregular cuboidal bases, 
articulating with the same number of bones as do the metacarpal; in having 
tapering triangular shafts, slightly concave from end to end on the plantar aspect; 
and in having laterally compressed heads with articular facets extending onto the 
plantar surfaces, where they are for the flexor tendons, and with lateral 
tubercles and depressions for the lateral ligaments. The line of their bases slopes 
from within outward and backward, and is interrupted by the mortising of the 
second between the internal and external Cuneiform bones. 
The first metatarsal, the stoutest and shortest, has on its base a large, slightly 
concave, kidney-shaped facet for the internal cuneiform, and an inconstant facet 
externally for the second metatarsal. The lower part of the base projects down- 
ward and slightly outward as the tuberosity, which attaches part of the peroneus 
longus externally and of the tibialis anterior internally. On the plantar surface 
of the large head are two deep grooves for the sesamoid bones. 
The second metatarsal is the longest; the others diminish in length to the fifth. 
Its base articulates in the mortise with the thiee cuneiform bones, and extern nib 
by two facets with the third metatarsal, and occasionally internally with the first 
metatarsal. . . 
The base of the third metatarsal articulates proximally with the external cunei- 
form, internally by two facets with the second metatarsal, and externally by a 
single facet with the fourth metatarsal. 
The base of the fourth metatarsal articulates proximally with the cuboid, 
internally with the third metatarsal by a single facet, and usually with the exter- 
nal cuneiform. Externally there is a single facet for the fifth metatarsal, bordered 
by a deep groove for ligaments. < 
The base of the fifth metatarsal articulates proximally with the cuboid, inter- 
nally with the fourth metatarsal. On its outer aspect it projects as a large rough 
tuberosity upon which the tendon of the peroneus brevis is inserted. Being sub- 
cutaneous, it is an important landmark on the outer border of the foot. 162 
THE BONES. 
THE PHALANGES. 
The 'phalanges (Figs. 181-184) resemble so closely those of the fingers that 
only the differences need be noticed. Those of the great toe are larger than those 
of the thumb, while those of the other toes are much smaller than those of the 
SESAMOID- 
I,1/ FIRST 
II PH A LANGES 
( SECOND 
FIRST I. 
PHALANGES* 
Fig. 182.—The bones of the right foot, viewed from below. (Testut.) 
DISTAL PHALANGES 
'corresponding fingers. The shafts of the phalanges of the first row, in the four 
smaller toes, are narrowed in the middle, being compressed laterally. In the 
same toes the phalanges of the second row are very short and stunted, especially THE FOOT AS A WHOLE. 
163 
those of the fourth and fifth toes, which are not infrequently ankylosed with the 
terminal phalanges. 
The two sesamoid hones in the tendon of the flexor brevis hallucis glide in 
the two grooves on the plantar aspect of the head of the first metatarsal bone. 
Sesamoid bones occasionally occur elsewhere in the foot. 
Ossification.—The metatarsal and phalangeal bones ossify exactly like the 
corresponding bones in the hand. 
THE FOOT AS A WHOLE (Figs. 181-184). 
The foot is narrowest at the heel and widens to the heads of the metatarsal 
bones. The bones of the foot form a longitudinal arch with a single pier, the 
calcaneum, behind, while the forward pier is formed by the heads of the meta- 
tarsal bones. It may be divided longitudinally into two parts in front, with a 
common support behind. The inner division consists of the hind two-thirds of 
Fig. 183.—The bones of the right foot, viewed from the outer side. (Testut.) 
the calcaneum, the astragalus, navicular, cuneiforms, and the three inner metatar- 
sals. It bears the greater part of the weight, and is the most raised from the 
ground. The outer division is formed by the calcaneum, bearing the cuboid and 
the two outer metatarsals, and acts mainly as a buttress to the inner arch. The 
longitudinal arch is supported largely by the plantar ligaments, while a trans- 
verse arch, having its two internal piers at the internal cuneiform and the first 
metatarsal, and its external piers at the cuboid and the fifth metatarsal, is formed 
by the wedge-shape of the cuneiform bones and of the bases of the metatarsals. 
Fig. 184.—The hones of the right foot, viewed from the inner side. (Testut.) 
The longitudinal arch is weakest between the astragalus and navicular, where 
it is liable to yield, giving rise to flat-foot. In this condition it is well seen that 
the arch is not quite straight from the heel to the toes, but is slightly convex 
internally and concave on the outer border. The astragalus inclining inward 164 
THE BONES. 
and the calcaneum outward in front, the upper and outer border of the former 
is found over the middle of the latter, making the internal malleolus appear more 
prominent. In infancy the head of the astragalus is inclined inward more than 
in the adult, so that the foot is then naturally inverted. 
The tuberosity of the navicular on the inner border of the foot and that of the 
base of the fifth metatarsal on the outer border, both readily felt through the soft 
parts, are the best guides to the medio-tarsal and tarso-metatarsal joints. The 
tuberosity of the fifth metatarsal is a finger’s breadth in front of the medio-tarsal, 
and directly in front of the tarso-metatarsal joint; that of the navicular is two 
fingers’ breadth behind the tarso-metatarsal and directly in front of the medio- 
tarsal joint. 
Homologies of the Bones of the Two Extremities. 
The following conclusions are generally admitted : The thoracic and pelvic 
limbs are constructed on the same type in their attaching girdles and their several 
segments. In the pelvic and shoulder girdles the ilium corresponds to the scapula, 
the ischium to the coracoid process, and the os pubis to the precoracoid, and per- 
haps to the clavicle. 
At an early stage of embryonic life the limbs are folded ventrally upon the 
body, and present pre- and post-axial borders and dorsal or extensor and ventral 
or flexor surfaces. Later, the upper limb rotates outward 45°, and the lower limb 
rotates inward 90°. This brings the flexor surface in the upper limb forward and 
inward, and in the lower limb backward. The small trochanter and internal 
condyle of the femur, the tibia, and the great toe in the lower limb are pre-axial, 
and correspond respectively to the great tuberosity and outer condyle of the 
humerus, the radius, and the thumb in the upper limb, etc. The patella in the 
lower limb and the olecranon in the upper have no corresponding parts in the 
other limb. 
The adult human skeleton is adapted in every part to maintain with ease the 
erect attitude by being nearly balanced around the line of the centre of gravity 
in the standing posture, and in this respect it differs from that of other mammals. 
Stability and strength are provided in the lower limbs, mobility and lightness in 
the upper. 
THE SKULL. 
The bones of the head, composing the skull, contain and protect the brain and 
sense-organs, as well as the commencement of the alimentary and respiratory 
tracts. With the exception of the lower jaw, the bones are immovably joined 
together by sutures, forming a bilaterally symmetrical, spheroidal figure, some- 
what compressed laterally. It is supported upon the vertebral column, with the 
upper segment of which it articulates. For description, the twenty-two bones of 
the skull are divided into two sets. The cranium, or brain-case, is the part above 
and behind, and comprises eight bones—viz. : 
f Occipital. 
Basilar bones, 1 ®Phe“oid- , . Roof bones, ( £wo ffieta,s- 
-i iwo temporals. _r rental. 
Ethmoid. 
The face is the lower and fore part, composed of six pairs and two single 
bones, or fourteen in all—viz. : in pairs, the maxillae, palate, inferior turbinate, 
nasal, lachrymal, and malar ; single bones, the vomer and mandible. The hyoid 
bone may also be classed here, as appendicular to the bones of the head. The 
base of the skull is preformed in cartilage, the roof and sides in membrane. THE OCCIPITAL BONE. 
165 
THE BONES OF THE CRANIUM. 
THE OCCIPITAL BONE. 
This lozenge-shaped bone (Figs. 185 and 186) forms the back and a part of 
the base of the skull. Its long diameter is directed from behind downward and 
forward. It consists of four parts, which meet around the foramen magnum. 
These parts are distinct at birth, and are represented by separate bones in lower 
vertebrates. Of these parts, the broad, flat, curved portion behind the foramen 
magnum, called the squamo-occipital, consists of two parts. The upper triangu- 
lar segment lying above the highest curved line represents the interparietal bone 
of lower vertebrates, and is sometimes separate in man. The two exoccipitals or 
condylar portions lie one on either side of the foramen magnum, and include the 
JLATERAL 
ANGLE 
FORAM £N 
MAGNUM 
-JUGULAR PROCESS 
ARROW IN ANTERIOR 
‘CONDYLAR FORAMEN 
basilar^ 
process* 
Fig. 185.—The occipital bone, viewed from below. (Spalteholz.) 
condyles and jugular processes. They join the squamo-occipital behind and the 
basi-occipital or basilar process in front. The latter extends forward from the 
foramen to the sphenoid line. The entire bone is flattened and much curved, and 
presents a concave cerebral surface and a convex external surface. 
The external surface is convex, and looks downward and backward behind, 
downward and forward in front. It presents behind, about the centre of the 
squamous portion, a well-marked prominence, the external occipital protuberance— 
an important landmark to be felt through the scalp. From this a median ridge, 
the external occipital crest, leads to the back of the foramen magnum. The pro- 
tuberance and crest give attachment to the ligamentum nuchse. A transverse 
ridge extends laterally on each side from the external occipital protuberance called 
the superior curved line (or middle nuchal line). It arches outward toward the 
lateral angle, and attaches the trapezius internally, and parts of the occipitalis, 
sterno-cleido-mastoid, and splenius capitis externally. Above this line is some- 
times to be seen a fainter ridge, the highest curved line (linea suprema or superior 
nuchal line). This is more curved, most marked mesially, and extends laterally 
toward the lateral angle, enclosing with the superior curved line a smooth, dense, 
semilunar area. It is often absent, but when present attaches the epicranial 
aponeurosis and a few fibres of the occipitalis. The surface above this line is 
evenly convex. The rough surface between the superior curved line and the 
foramen magnum is divided into two rough areas on each side by the inferior 
curved (or nuchal) line, which curves outward and then downward from near the 
middle of the crest to the jugular process. The space above the inferior line 
receives the complexus mesially. The lower space is occupied by the recti capitis 166 
THE BONES. 
posteriores major and minor and the obliquus superior. On the external or under 
surface of the condylar portions we see the condyles, which lie at the sides of the 
anterior half of the foramen magnum. Through them the head rests upon and 
articulates with the atlas. Their smooth, elliptical, convex surfaces, cartilage- 
clad in the recent state, converge in front and look downward and outward. On 
the median side of each is a rough impression or tubercle for the lateral odontoid 
or check-ligaments. Behind each condyle is a depression, the posterior condylar 
fossa, which receives the hind edge of the articular facet of the atlas in extension 
of the head. At the bottom of the depression is sometimes seen the external 
opening of the posterior condylar foramen, for the passage of a vein from the 
lateral sinus. It is frequently absent on one or both sides. The base of the 
condyle is traversed by the anterior condylar foramen, which passes outward and 
forward from the cranium above the foramen magnum, and transmits the hypo- 
glossal nerve. External to each condyle the jugular.(from jugulum, 11 throat”) 
process presents an inferior rough surface, which lies above the transverse process 
of the atlas, and gives insertion to the rectus capitis lateralis. The inferior sur- 
face of the basilar portion is inclined forward, is narrower in front than behind, 
and is transversely convex. It presents a small median pharyngeal tubercle, 
attaching a process from the fibrous aponeurosis of the pharynx. On either side 
of this it is rough for the recti capitis anteriores, major and minor. A part of 
this surface can be palpated, though not easily, through the mouth. 
On the internal or cerebral surface the squamous (“ scaly ”) portion presents a 
concave surface divided by a transverse and a longitudinal ridge into four fossse, the 
two superior for the occipital cerebral lobes and the two inferior for the cere- 
bellar hemispheres. The intersection of these ridges is marked by the internal 
occipital protuberance. The longitudinal ridge above the protuberance extends to 
the superior angle, and is grooved for the superior longitudinal sinus, the edges of 
which attach the falx cerebri. The transverse ridges extend to the lateral angles, 
are similarly grooved for the lateral sinuses, and to the edges of the groove is 
attached the tentorium cerebelli. The groove for the longitudinal sinus passes to 
one side, usually the right, of the internal occipital protuberance, where the 
groove is deeper and lodges the torcular HerophUi (“ wine-press of Herophilus ”'). 
The sharp vertical ridge below the protuberance, called the interned occipital crest, 
attaches the falx cerebelli. It passes to the foramen magnum and spreads out 
into its margin. On the upper surface of the jugular process is seen a deep 
groove leading to a notch, the jugular notch, on the anterior border of the jugular 
process. This notch is joined by a notch on the petrous portion of the tem- 
poral bone, and thus forms the jugular foramen (foramen lacerum posterius). The 
groove lodges part of the sigmoid or terminal portion of the lateral sinus. Sepa- 
rating this groove from the foramen magnum is the jugular eminence, with the 
intracranial opening of the anterior condylar foramen internally, and that of the 
posterior condylar foramen externally (on the side of the groove). The upper 
surface of the basilar process presents a central groove, the basilar groove, slant- 
ing upward and forward for the medulla. On either margin of this surface is 
half of the groove for the inferior petrosal sinus. 
Angles.—The superior angle, as well as the two lateral, belong to the squamous 
portion. It fits into the angle formed by the meeting of the posterior superior 
angles of the parietal bones, and corresponds to the posterior fontanelle in the 
foetus. The lateral angles at the outer ends of the superior curved lines occupy 
the angles between the parietal bone and the mastoid portion of the temporal on 
either side. The anterior or inferior angle is represented by the oblong, anterior 
surface of the basilar portion, united to the body of the sphenoid by cartilage 
until the age of twenty years, afterward by bone. 
Borders.—The two superior borders extend between the superior and lateral 
angles, and are convex and deeply serrated. They articulate with the posterior 
borders of the parietals, and form the lambdoid (“ lambda-like ”) or parieto-occi- 
pital suture. The two inferior borders extend between the lateral and antero- THE OCCIPITAL BONE. 
167 
inferior angles, and are uneven and less deeply serrated. Between the lateral 
angles and the jugular processes they articulate with the mastoid portions of the 
temporals in the occipito-mastoid suture. The small rough extremity of each 
jugular process articulates with the jugular facet of the petrous portion of the 
temporal bone by synchondrosis until about the twenty-fifth year, when the union 
becomes osseous. In front of the jugular process is the smooth jugular notch (see 
above). Between this notch and the antero-inferior angle the borders are rough 
for articulation with the petrous portion of the temporal bone. A somewhat 
octagonal form is not infrequently presented by this bone, due to the projection 
of the jugular processes and the middle of the superior borders. 
The foramen magnum is oval in shape, with the long axis directed from before 
backward. It is encroached upon laterally in its fore part by the condyles, and 
transmits the upper end of the spinal cord with its membranes and accompany- 
ing structures. From the condyles, thick ridges of bone, which strengthen the 
skull and transmit its weight to the condyles, pass in four directions—viz., for- 
FO R A M E N 
MAGNUM 
process 
ugular notch 
Harrow in anterior 
CONDYLAR FORAMEN 
Fig. 186.—The occipital bone, viewed from above. (Spalteholz.) 
ward into the basilar process, laterally into the jugular processes, backward 
around the foramen, and thence upward as the occipital crest, etc. 
Development.—The basilar and condylar portions ossify each from a single 
centre. The squamous portion has four centres in two laterally disposed pairs— 
a pair above in the interparietal portion, and a pair below in the supraoccipital 
portion. These two pairs usually unite, but may remain separate through life, 
forming ah interparietal bone, as in lower vertebrates ; or, more commonly, two 
lateral fissures remain, a condition usually found at birth. The condylar portions 
join the squamous in lines extending outward from the posterior margin of the 
foramen magnum, and they join the basilar portion in lines passing through the 
anterior extremities of the condyles. The centres for the interparietal portion 
are deposited in membranes, those for the rest of the bone in cartilage. 
Varieties. There is sometimes seen a groove for the occipital sinus along the 
internal occipital crest. The jugular notch is often found partly subdivided by a 
small intrajugular process, and it is frequently separated from the groove tor the 
sinus by a thin transverse ridge. A projection sometimes found beneath the 
jugular process, the paramastoid process of many mammals, may rarely be so 
long as to meet the transverse process of the atlas. Frequently the anterior con- 168 
THE BONES. 
dylar foramen is subdivided by a thin bony spicule. Rarely the basilar process 
at the margin of the foramen articulates with the odontoid process, A median 
membranous space from the foramen magnum backward to the middle of the 
supraoccipital is of interest, because in rare cases, when not ossified, it may allow 
hernia of the brain and its membranes. 
Articulations.—By sutures the occipital bone is connected with the two parie- 
tals, the two temporals, and the sphenoid, and by the condyles it articulates with 
the atlas. 
THE PARIETAL BONE. 
The parietal (“wall”) bones (Figs. 187, 188) are two symmetrical, quadri- 
lateral plates which form a large part of the vault and sides of the skull, and are 
interposed between the frontal and the occipital bones. 
The external surface is convex, the 
convexity being greatest near the centre, 
at the parietal eminence, most marked in 
young bones. Arching across the bone 
just below this are the superior and 
inferior temporal ridges, the bone between 
which is smoother than elsewhere. The 
lower ridge, better marked and more 
constant, limits the temporal fossa and 
the attachment of the temporal muscle. 
The upper ridge, when present, gives 
attachment to the temporal fascia. The 
surface above it is covered by fascia and 
the scalp. Not far from the hind end 
of the upper border is the small parietal 
foramen when present. 
The internal surface is concave, and 
marked by shallow depressions and 
Fig. 187—The right parietal bone, outer surfaci 
(Henle.) 
ndges tor the cerebral convolutions, and by narrow grooves for branches of the 
middle meningeal artery, which run upward and backward from below. The 
largest of these runs from the 
projecting anterior inferior angle, 
often as a canal, for a short dis- 
tance, and is useful in determin- 
ing the side to which the bone 
belongs. Along the superior bor- 
der is a half-groove, completed 
by the one on the opposite bone, 
and lodging the superior longitu- 
dinal sinus. Near this groove, 
in bones of adults, and especially 
of the aged, small irregular de- 
pressions for the Pacchionian 
bodies are seen. A small part of 
the groove for the lateral sinus 
often crosses the inner aspect of 
the posterior inferior angle. 
Borders.—The superior, ante- 
rior, and posterior borders are 
deeply serrated, and the latter 
two, and to a less extent the first, 
are alternatelv bevelled at the ex- 
ANTERIOR ANGLE 
Fig. 188.—The right parietal bone, inner surface. (Testut.) 
pense of the outer and inner surfaces, thus alternately overlapping and being 
overlapped by the adjacent bones. The bone is thus so" strongly wedged in as to THE FRONTAL BONE. 
169 
prevent dislocation and to strengthen the cranial vault. The superior border 
forms with that of the opposite bone the sagittal (“ arrow-like ”) suture. The 
anterior borders of the pair articulate with the frontal bone in the fronto- 
parietal or coronal (“ crown ”) suture, and meet one another at nearly a right 
angle in European skulls, while the posterior borders, which form the lambdoid 
suture by articulation with the occipital, meet at an obtuse angle. The inferior 
border has three divisions. Behind, it is serrated for a short distance to articulate 
with the mastoid portion of the temporal bone in the parieto-mastoid .suture. In 
front of this the border is thin, concave, and externally bevelled and fluted, 
where it is overlapped by the squamous portion of the temporal in the squamous 
suture. The great wing of the sphenoid overlaps the front inch or so, forming 
the spheno-parietal suture. 
Angles.—Of the superior angles the anterior is at the bregma (“ sinciput ”), 
the posterior at the lambda (Greek letter A). The projecting anterior inferior angle 
is at the pterion (“wing”), and is sometimes excluded from articulation with 
the sphenoid by the contact of the squamosal and frontal. 
Ossification occurs in membrane from a single centre and commences at the 
site of the parietal eminence. 
Varieties.—Rarely a horizontal suture divides the bone into two parts. A 
large opening is very rarely seen at the site of the parietal foramen. 
THE FRONTAL BONE. 
The frontal (“ forehead”) bone (Figs. 189-191) forms the skeleton of the fore- 
head, and receives the frontal lobes of the brain in the concavity between the 
FRONTAL 
EMINENCE 
.TEMPORAL CREST 
JreuPRAORBITAI’I 
» FORAMEN ' 
-EXTERNAL ANGULAR 
PROCESS 
supraorbital! 
RIDGE 
NASAL SPINE 
INTERNAL ANGULAR 
PROCESS 
Fjg. 189.—The frontal bone, seen from in front. (Testut.) 
main or vertical portion, which arches upward and backward from the orbital 
margin, and the two thin horizontal or orbital plates, which extend backward from 
the same point, separated by a median gap, the ethmoidal notch. 
The anterior or external surface is convex, and most strongly so at the fronted 
eminences, a little below the centre of each lateral half. Below and separated from 
these by shallow grooves are the arched superciliary (“ above the lashes ) ridges, 
converging: in the median line to the nasal eminence, below which is the smooth 
glabella (“"little smooth place ”)• Traces of the metopic (“ frontal ”) suture which 
originally separated the two halves of the frontal, usually persist in the glabella. 
Behind the superciliary ridges lie the frontal onuses which cause the prominence 
of the ridges in the male. The arched supraorbital (“ above the orbit ) ridges, 
more sharply marked externally, limit this surface below and torm the anterior 170 
THE BONES. 
margin of the orbital roofs. At about the junction of their inner and middle 
thirds is the supraorbital notch, sometimes a foramen, for the supraorbital nerve 
and artery. The supraorbital arch ends in two downward projections, the external 
and internal angular processes, of which the external is a strongly projecting land- 
mark, which articulates with the malar bone, while the internal is slightly marked 
and articulates with the lachrymal bone. From the external angular process the 
temporal crest arches upward and backward, continuous with the ridges on the 
parietal bone. It separates the frontal part from the temporal area, below and 
behind it, which forms part of the temporal fossa and attaches the temporal 
muscle. 
The inferior surface consists of the orbital surfaces of the triangular orbital 
plates, which form the greater part of the roof of the orbits. Their inner margins 
are parallel; the outer pass backward and inward. Close behind the outer part 
INTERNAL ANGULAR 
PROCESS 
'EXTERNAL 
ANGULAR 
PROCESS 
NASAL SPINE 
Fig. 190—The frontal bone, seen from behind. (Spalteholz.) 
of the supraorbital ridge this surface presents the lachrymal fossa lodging the 
lachrymal gland; and behind the inner end of the ridge there is a depression, the 
trochlear fossa (more rarely a tubercle), for the pulley of the superior oblique 
muscle of the orbit. Between and in front of the internal angular processes is 
the nasal notch. This is bounded above by a semilunar, serrated surface, which 
articulates with the upper ends of the nasal bones mesially and the nasal processes 
of the superior maxillae laterally. It is bounded behind by a rough, nearly 
vertical surface, the nasal process (Henle), which projects behind, supports and 
articulates with the upper ends of the nasal and maxillary bones, which form the 
bridge of the nose. From the centre of this surface the nasal spine projects 
downward and forward as a sharp process, which forms a part of the septum of 
the nose, between the crests of the nasal bones and the vertical plate of the 
ethmoid. The spine commences behind the nasal process as a median ridge, on 
either side of which is a narrow groove forming a small part of the roof of the 
nasal fossae. Between the back of these grooves and the internal angular process 
notice the openings of the two frontal sinuses, which are placed between the outer 
and inner tables of the bone. The sinuses lie behind the superciliary ridges, extend 
a variable distance over the orbits, and are separated by a thin vertical partition, 
usually displaced to the left. Behind these openings, and between the ethmoidal 
notch and the inner margins of the orbital surfaces, are a series of depressions 
forming the roofs of cells, and two transverse grooves. These are completed by 
articulation with the lateral masses of the ethmoid to form respectively the THE TEMPORAL BONE. 
171 
ethmoidal cells and the anterior and 'posterior ethmoidal canals. The anterior canals 
transmit the nasal nerve and anterior ethmoidal vessels; the posterior canal, the 
posterior ethmoidal vessels. 
The cerebral surface forms a deep concavity, encroached upon but slightly by 
the convexity of the upper surfaces of the orbital plates, which form the greater 
part of the floor of the anterior cranial fossa. The orbital plates and the adjoin- 
ing bone present marked depressions and ridges for the frontal convolutions. 
TROCHLEAR 
FOSSA 
NASAL SPIN El 
ISUPRAORBITAL NOTCH 
C H RYM A L FOSSA 
SUPRAORBITAL 
Ridge 
JEXTERNAL ANGU- 
LAR PROCESS 
FiG.l9l.~The frontal bone, seen from below. (Testut.) 
Elsewhere the bone is smoother, except for a median furrow, the frontal sulcus. 
This starts from the upper border, with pits for Pacchionian bodies on both sides, 
and narrows down below to the thin prominent frontal crest. The superior longi- 
tudinal sinus is lodged in the sulcus, and the falx cerebri is attached to the crest 
and the ridges of the sulcus. The termination of the crest, by articulation with 
the crista galli of the ethmoid, completes the foramen caecum (“ blind hole ”). 
When not closed below, this foramen transmits a small vein from the nose. 
Borders and Articulations.—The posterior border articulates with the parietal 
bone in the coronal suture, nearly as far outward as a rough triangular surface. 
This triangular surface articulates with the great wing of the sphenoid, forming 
the posterior half of the outer margin of the orbital plate. It is continuous behind 
with the thin posterior margin of the orbital plate, which articulates with the 
small wing of the sphenoid. The malar bone articulates with the fore part of 
the outer margin of the orbital plate. The parallel inner borders of the orbital 
surface articulate with the os planum of the ethmoid behind and the lachrymal in 
front. The margins of the ethmoidal notch articulate with the cribriform plate 
of the ethmoid laterally, and the crista galli in front. (The articulations of the 
nasal notch and spine have been described above.) 
Ossification proceeds from two centres in the membrane at the site of the frontal 
eminences. At birth there are two separate lateral halves, soon united by the 
median frontal or metopic suture, which is usually obliterated by ossification, ex- 
cept for a trace at the glabella, but sometimes persists throughout life. The 
frontal sinuses appear about the seventh year as forward growths from the ante- 
rior ethmoidal cells, and increase up to old age. They may invade the roof of 
the orbit quite extensively. 
THE TEMPORAL BONE. 
The temporal (“temple”) hone (Figs. 192-195) forms part of the side and 
base of the skull, contains the organ of hearing, and articulates with the lower 
jaw. Although it is usually described in three parts—viz. squamous, mastoid, 
and petrous—the three parts separable at birth are the squamous, petro-mastoid, 
and tympanic. „ 
The Squamous Portion.—This is a thin plate, extending upward and forward 
at right angles to the petrous, and forms part of the side-wall of the middle fossa 
of the skull. The outer surface, but slightly convex, is smooth, except tor a ver- 
tical groove above the external auditory meatus for the middle temporal artery. 172 
THE BONES. 
It forms part of the temporal fossa, and is delimited from the mastoid surface 
behind by the curved supramastoid crest. This crest is continued forward, just 
above the external auditory meatus, to the zygoma (“ yoke ”), a process of bone 
which projects, shelf-like, from the lower part of this surface outward, and then, 
twisted on itself, continues forward. In its forward projection the smooth inner 
DIGASTRI 
FOSSA 
-GLASERIAN FISSURE 
Fig. 192.—-The right temporal bone, outer surface. (Testut.) 
surface and lower border give origin to the masseter, the sharp upper border 
attaches the temporal fascia, and the serrated and bevelled anterior extremity 
articulates with the malar. Two ridges, or roots, extend from its base, the pos- 
terior backward and the anterior inward, enclosing between them a transversely 
oval, smooth depression, the glenoid fossa, divided into two parts by the nearly 
ZYGOMATIC 
PROCESS 
EUSTACH lAN TUBE- 
CAROTID CANAL- 
INTERNAL 
MEATUS. 
IMASTOID FORAMEN 
'aqueductus 
VESTIBULI 
Fig. 193.—The right temporal hone, viewed from the mesial plane. (Testut.) 
transverse fissure of Glaser. For articulation with the lower jaw the front half 
of the fossa is coated with cartilage, together with the convex nearly transverse 
ridge, the eminentia articularis, which limits it in front and forms the anterior 
root of the zygoma. At the outer end of the latter root is a tubercle (preglenoid) THE TEMPORAL BONE. 
173 
for attachment of the external lateral ligament of the lower jaw. The posterior 
root divides into two branches, of which the upper is the supramastoid crest, and 
the lower descends in front of the external auditory meatus to the tympanic bone 
at the Glaserian fissure as the postglenoid process, very prominent in young bones. 
In front of the articular eminence is a small, smooth triangular surface belonging 
to the zygomatic fossa, and separated from the temporal surface by a slight ridge. 
The external pterygoid muscle glides over it. 
The internal surface is marked by impressions for the cerebral convolutions 
and by grooves for the middle meningeal arteries. Where it joins the petrous 
portion there is seen in young, and often in old, bones the remains of the petro- 
squamous suture passing from the angle between these two portions in front to the 
parietal notch between tire squamous and mastoid portions behind. The arched 
border between these two angles or notches describes about two-thirds of a circle, 
and is thin, bevelled, and fluted on its inner surface above, overlapping the 
parietal, and in front is serrated and bevelled on its inner surface above and on 
its outer surface below, articulating with the great wing of the sphenoid. 
The Petro-mastoid Portion.—This segment of the temporal is an irregular, 
four-sided pyramid of very dense bone, whose rough truncated apex is directed 
forward and inward to the foramen lacerum medium, and whose base, directed 
outward and backward, is formed by the less dense mastoid portion. It is usu- 
ally described as three-sided, the fourth or outer surface being mostly covered by 
the tympanic bone. 
The mastoid portion of the petrosal presents a triangular rough external sur- 
face, prolonged downward and forward into the nipple-shaped mastoid process, 
which affords attachment to the sterno-mastoid, splenius capitis, trachelo-mastoid, 
and occipitalis. Internal to the mastoid process is the deep digastric groove for 
the digastric muscle, internal to which is the shallow groove for the occipital 
artery. Its internal or cerebral surface forms a small part of the posterior cranial 
fossa, and is separated from the petrosaj pyramid 
by the deep groove for the sigmoid portion ot the 
lateral sinus. The mastoid foramen, transmitting 
a vein, opens internally on or near the rear wall 
of this groove, and externally near the posterior 
border of the mastoid portion. Ihe upper border 
of this portion articulates with the parietal, the 
posterior border with the occipital. The suture- 
line between the squamous and mastoid portions 
lies a little below the crest, and 
runs from the parietal notch to the middle of the 
external meatus. The mastoid process about 
puberty enlarges and becomes filled with a num- 
ber of air- cells (mastoid cells), connected with a 
larger cavity, the mastoid antrum (“ cave ), which 
is present and comparatively large at and 
communicates with the upper part of the middle 
ear or tympanum. The antrum is bounded ex- 
ternally by that part of the squamous portion 
below the supra mastoid crest, which is exceed- 
ingly thin in children, while superiorly the back 
of the roof of the tympanum (legmen tympani, 
“ cover of the drum”) separates it from the 
middle cranial fossa. 
MASTOID CELLS 
Pig. 194.—Section through the mas- 
toid cells, showing their communication 
with the middle ear. (W. W. Keen.) 
The Petrous Portion.—Of the two intracranial surfaces ot tins portion, me 
posterior surface looks backward, inward, and slightly upward into the posterior 
fossa of the base of the skull. From near its centre the internal auditory meatus, 
which transmits the facial and auditory nerves, passes outward for about two- 
fifths of an inch to a plate of bone, the lamina cribrosa (“ sieve-like layer ). 174 
THE BONES. 
This is so called from the number of larger and smaller apertures for the sub- 
divisions of the eighth or auditory nerve on either side of a transverse falciform 
(•‘sickle-shaped”) crest, above which, in front, is the internal orifice of the aque- 
duct of Fallopius for the seventh or facial nerve. The aqueduct of Fallopius 
passes outward to the genu, where it bends backward to pass along above and in- 
ternal to the tympanum, behind which it bends sharply downward to the stylo- 
mastoid foramen. Behind the meatus is the small, slit-like opening of the aque- 
ductus vestibuli (“water-pipe of the vestibule”), occupied in the adult by vessels 
and a process of dura, and above and in front of the latter is a small opening, 
the remains of the Jioccular fossa, very large in young bones. 
The anterior surface looks forward, outward, and upward into the middle 
cranial fossa. A depression is seen near the apex for the Gasserian ganglion, 
external and inferior to which is the end of the bony carotid canal. Behind this 
are two small grooves leading backward and outward to foramina—the larger 
and internal to the hiatus (“gaping”) Fallopii, which leads to the geniculate 
ganglion in the aqueduct of Fallopius, and transmits the great superficial petrosal 
nerve, while the smaller and external is for the small petrosal nerve. Behind 
these, and between the petro-squamous suture externally and an eminence formed 
by the superior semicircular canal internally, the bone is thin and forms the roof 
of the tympanum. 
The inferior or basilar surface presents posteriorly, between the mastoid and 
styloid processes, the stylo-mastoid foramen, the exit of the facial nerve from the 
aqueduct of Fallopius. The styloid, process itself projects downward and for- 
ward, for possibly 2 inches, from its base, which is imbedded between the vaginal 
process of the tympanic and the petrosal bone. It attaches two ligaments and three 
Iglaserian 
FISSURE 
[CAROTID CANAL 
•VAGINAL PROCESS 
■STYLOID PROCESS 
.STYLOMASTOID 
FORAMEN 
Fig. 195.—The right temporal bone, viewed from below. (Testut.) 
muscles. Internal to this foramen and process is the small quadrilateral jugular 
facet, with which the jugular process of the occipital unites by cartilage until 
ossification at the twentieth year. In front of and internal to this facet is the 
smooth, deep jugular fossa, which with the jugular notch of the occipital com- 
pletes the jugular foramen. In front of the fossa is the carotid foramen, the lower 
end of the carotid carnal, for the internal carotid artery, which ascends vertically, THE TEMPORAL BONE. 
175 
and then passes horizontally forward and inward to the outer side of the apex of 
the bone at the foramen lacerum medium (“ middle torn hole ”). Internal to the 
carotid foramen and reaching to the apex is a quadrilateral surface for the origin 
of the tensor tympani and levator palati muscles. Small Foramina on this Sur- 
face.—1. Between the jugular fossa and the carotid foramen is the tympanic 
canaliculus for Jacobson’s nerve (the tympanic branch of the glosso-pharyngeal). 
2. In the jugular fossa is the foramen for the auricular branch of the vagus 
nerve. 3. Small tympanic branches of the carotid plexus pierce the walls of the 
carotid canal. 4. The aqueduct of the cochlea begins in a triangular depression 
of the posterior inferior margin, just below the internal meatus. 
The narrow external or tympanic surface looks slightly forward, and is hidden 
by the tympanic plate, except for a variable extent of the outer wall of the carotid 
canal in front. On removal of the tympanic bone this surface is seen to form the 
inner wall of the tympanum (“ drum ”). In the angle between it and the tympanic 
roof is seen the projection of the Fallopian canal, which bends downward in the 
angle between the inner and posterior tympanic surfaces, and lodges the facial nerve. 
Below this is the fenestra ovalis (“ oval window ”), opening into the vestibule and 
situated above the promontory, which is grooved for the tympanic plexus of 
nerves. Below and behind the promontory is the fenestra rotunda (“ round win- 
dow ”), opening into the cochlea. The surface narrows in front to the bony 
canals for the tensor tympani muscle above and the Eustachian tube below, which 
are completed externally by the tympanic plate. The two canals are separated 
by the delicate processus cochlear if or mis (“ conchshell-shape ”), which projects out- 
ward and upward. 
The superior border, grooved for the superior petrosal sinus, attaches the ten- 
torium cerebelli, a process of which bridges over a notch (trigeminal notch) near the 
apex of the bone for the passage of the trigeminal or fifth nerve. A spicule of 
bone near the front end of this border is often continued by a fibrous band, rarely 
by bone (petro-sphenoidal ligament or process), to the side of the dorsum sellse of 
the sphenoid, completing a foramen for the sixth nerve and the inferior petrosal 
sinus. The posterior inferior border completes the groove for the inferior petrosal 
sinus by its articulation with the occipital bone internal to the jugular foramen. 
The anterior superior and anterior inferior borders are shortened by articulation 
with the squamosal and tympanic bones respectively. The angle between the 
squamous and petrous portions receives the spine of the sphenoid and presents 
the front orifice of the bony Eustachian canal, to which the cartilaginous part is 
attached. 
The Tympanic Bone.—In the adult this part of the temporal forms the tym- 
panic plate. This constitutes the hind, non-articular portion of the glenoid fossa, 
which lodges part of the parotid gland, and is separated from the squamous por- 
tion in front by the Glaserian fissure._ Interiorly it forms the sharp, projecting 
vaginal (“ sheath-like ”) process ; superiorly it coalesces with the squamous portion, 
and forms the front, lower, and part of the icar walls of the bony external audi- 
tory meatus. The latter outward in the curved, rough, free margin of 
the external auditory process, which attaches the cartilage of the ear. Internally 
it fuses with the petrosal, and forms the outer wall of the tympanum. Behind it 
joins the mastoid portion in the auricular fissure. 
The bony external auditory meatus is elliptical, slightly in the 
middle and directed inward and a little forward to the tympanum. Its internal 
orifice is smooth and grooved for the tympanic membrane; the external orifice is 
bounded by the external auditory process except above, where the posterior root 
of the zygoma bounds it. Externally the Glaserian fissure is closed; internally 
it is double, and is occupied by a descending process of the tegmen tympani of 
the petrous portion, which separates the tympanic and squamosal bones, and forms 
most of the outer wall of the Eustachian and tensor tympani canals. Between 
this process and the tympanic plate the fissure transmits to the tympanum the 
tympanic branch of the internal maxillary artery, and lodges the slender process 176 
THE BONES. 
of the malleus. More internally it presents the canal of Huguier, by which the 
chorda tympani nerve issues. 
Articulations.—The temporal bone articulates above with the parietal, in 
front with the sphenoid and malar, below with the mandible, behind and inter- 
nally with the occipital. 
Ossification.—The squamosal and tympanic bones ossify in membrane, each 
from a single centre ; the petrous portion and styloid process in cartilage, the former 
from four centres, the latter from two. The foetal tympanic bone forms an incom- 
plete ring, which encloses the tympanic membrane. It is open above with its 
free ends united to the squamosal. Two tubercles growing from the front and 
back of this ring meet in the floor of the meatus, enclosing a foramen, which is 
gradually (though not always) closed, and thus the tympanic plate is formed. At 
birth the mastoid process, articular eminence, and tympanic ring are flat, the 
glenoid fossa is shallow, and the hiatus Fallopii opens at the genu of the 
canal. 
THE SPHENOID BONE. 
The sphenoid or wedge-hone (Figs. 196-198) forms a part of all three fossae 
of the base of the skull and of the orbits and nasal fossae. It is very irregular 
MIDDLE CLINOID 
PROCESS. 
ETHMOID SPINEj 
OPTIC FORAMEN. 
"ANTERIOR CLINOID 
PROCESS. 
-FORAMEN RO- 
TUNDUM. 
.LI NGU LA. POSTERIOR CLI- 
NOID PROCESS. 
-SPINOUS PROCESS. 
VIDIAN 
CANAL. 
FORAMEN 
OVALE. 
Iforamen 
SRI NOSUM. 
Fig. 196.—The sphenoid bone, viewed from above. (Testut.) 
in shape, and consists of a body, two pairs of wings, and a pair of pterygoid 
processes. 
Body.—The central cuboidal part or body presents a superior surface, which 
in its hind part, in the posterior cranial fossa, continues the basilar groove of the 
occipital and slants upward and forward to a quadrilateral projecting plate, the 
dorsum settee (“back of the saddle”). The upper angles of the latter project out- 
ward as the posterior clinoid (“ bed-like”) processes, attaching the tentorium cere- 
belli. It overhangs a deep depression, the pituitary fossa or sellaturcica (“ Turk- 
ish saddle ”), which lodges the pituitary body and forms the isthmus or narrow 
median portion of the middle cranial fossa. This depression is bounded in front 
by a transverse elevation, the olivary eminence, behind which on each side projects 
a small tubercle, the middle clinoid, process. In front of the eminence the slight 
optic groove supports the optic commissure, and leads laterally to the optic foramina. 
The surface in front of this is on a slightly higher level, and forms part of the 
floor of the anterior cranial fossa. It ends in front in a projection, the ethmoidal 
spine, for articulation with the cribriform plate of the ethmoid, and laterally it is 
continuous with the superior surfaces of the small wings. Each lateral margin of 
this surface is bevelled by the winding cavernous groove, which lodges the inter- 
nal carotid artery in its forward passage and the cavernous sinus. The hind end THE SPHENOID BONE. 
177 
of this groove is bounded on either side by a bony projection, internally by the 
petrosal process, which springs from the side of the base of the dorsum sc Ike and 
fits against the apex of the petrous portion of the temporal bone, and externally 
by the lingula (“ little tongue ”), a thin lamella projecting backward between the 
body and the great wing. The posterior surface is united to the basilar process 
of the occipital by cartilage in early life, and by bony union in the adult. On 
ETHMOID 
SPI NE. 
OPTIC FORAMEN. 
f FORAMEN 
-rotundum. 
FORAM EN 
-SPINOSUM. 
CREST. 
VI DIA Nl 
CAN AL.| 
INTERNAL- 
PLATE. 
PTERYGOID NOTCH. 
HAMULAR 
PROCESS. 
Fig. 197—The sphenoid bone, viewed from in front. (Testut.) 
the anterior surface the vertical sphenoidal crest projects in the middle line, below 
the ethmoidal spine, and articulates with the vertical plate of the ethmoid. On 
either side, superiorly, are the rounded orifices of the two sphenoidal sinuses, which 
occupy much of the body of the bone. They are unequally divided by a vertical 
lamina, the sphenoidal septum, continued back from the crest. These openings 
and the surfaces beneath them are on the roof of the nasal fossse, and the rough 
surfaces on either side articulate with the lateral masses of the ethmoid above and 
with the orbital processes of the palate bones below. Much of this surface on 
either side, between the articular areas and the crest and below the orifices, is 
formed by the sphenoidal turbinate (“ top-shaped ”) bones. These are triangular 
POST. CLIN. PR. 
SMALL WING 
Fy. CAN ALTO 
SPINOUS PROCESS 
■FORAMEN OVALE 
'artic. with 
I OCCIPITAL 
FORAMEN SPINOSUM 
HAMULAR PROC. 
Fig 198 —The sphenoid bone, viewed from behind. (Testut.) 
or conical in shape, with the apex directed downward and backward. They _ are 
formed separately, often come away with the ethmoid or palate bones in disarticu- 
lating, and sometimes appear in the orbit. The inferior surface presents in front 
a median ridge, the rostrum (“ beak ”), continuous with the crest and received 
between the ate and the vomer. The surface on either side forms part of the 
roof of the pharynx, and is partly covered by the vaginal processes of the intei- 178 
THE BONES. 
nal pterygoid plate. Each lateral surface attaches the two wings, and between 
the latter forms the inner boundary of the sphenoidal fissure and the back of the 
inner orbital wall. 
The small or orbital wings are thin, triangular, horizontal plates, extending out- 
ward from the fore part of the lateral surfaces on a level with the corresponding 
part of the superior surface. Their smooth superior surfaces form the hind part 
of the floor of the anterior cranial fossa; the inferior surfaces form the back of 
the roof of the orbits and the upper margin of the sphenoidal fissures. The ser- 
rated anterior border articulates with the orbital plate of the frontal bone, by 
which it and the pointed outer extremity are separated from the great wing, exter- 
nal to the sphenoidal fissure. The free posterior border is received into the 
Sylvian fissure of the brain. It is the boundary between the anterior and middle 
cranial fossae, and ends postero-internally in a knob, the anterior clinoid process, 
which attaches the tentorium cerebelli. The base of the wing is divided into two 
roots by the outward and forward passage of the optic foramen, which transmits 
the optic nerve and the ophthalmic artery. 
The great or temporal wings project outward and upward from the lower part 
of the sides of the body, and present three surfaces—cerebral, orbital, and tem- 
poro-zygomatic. The concave cerebral surface forms part of the middle cranial 
fossa, and presents at the fore part of its junction with the body, and below the 
sphenoidal fissure the forward-directed foramen rotundum for the superior max- 
illary nerve. Behind and a little external to this is the large foramen ovale, 
directed downward, for the inferior maxillary nerve. This part of the bone pro- 
jects horizontally backward into the sharp cdar (“ wing-like ”) spine of the sphe- 
noid, which occupies the angle between the squamous and petrous portions of the 
temporal bone. From its under surface the sharp spinous process projects down- 
ward, attaching the spheno-mandibulary ligament. The small foramen spinosum 
perforates the spine and transmits the middle meningeal artery, grooves for 
which cross this surface. The external or temporo-zygomatic surface forms part of 
the temporal fossa above and of the zygomatic fossa below the transverse ptery- 
goid (“ wing-like”) ridge which crosses it. The zygomatic surface looks down- 
ward, is continuous with the outer surface of the external pterygoid plate, and 
presents the lower orifices of the foramina ovale and spinosum. The anterior or 
orbital surface looks forward and inward. Its upper quadrilateral part forms the 
greater part of the outer wall of the orbit, which is separated by a ridge, forming 
the outer lip of the spheno-maxillary fissure, from a small area below, which looks 
into the spheno-maxillary fossa and presents the anterior orifice of the foramen 
rotundum. The posterior border in its inner third bounds the foramen lacerum 
medium in front, and presents the posterior opening of the Vidian canal. This 
canal tunnels the base of the internal pterygoid plate sagittally and transmits the 
Vidian nerve and artery. In its outer two-thirds this border articulates with the 
petrosal, completing inferiorly a groove for the cartilage of the Eustachian tube. 
The external border is bevelled internally below and externally above, and articu- 
lates with the squamosal. The .superior border overlaps the anterior inferior 
angle of the parietal bone. Internal to and in front of this articulation is a rough 
triangular surface which articulates with a similar rough triangular surface on the 
frontal, and is formed between the upper margins of the three surfaces. The 
cranial and orbital surfaces converge and meet in a sharp free border which 
bounds the sphenoidal fissure inferiorly. The anterior margin or malar crest 
separates the orbital and temporal surfaces, and articulates with the malar bone 
and sometimes with the superior maxilla at its lower angle. The obliquely 
elongated sphenoidal fissure between the body and the two wings is closed exter- 
nally by the frontal bone, and transmits to the orbit the third, fourth, sixth, and 
ophthalmic divisions of the fifth nerves, and the ophthalmic vein. 
The two pterygoid processes consist each of two plates, joined in front, but 
diverging behind, which project downward and slightly forward from the lower 
aspect of the base of the great wing. THE ETHMOID BONE. 
179 
The external pterygoid plate, broad and thin, lies in a plane directed back- 
ward. The internal surface affords origin to the internal pterygoid muscle, the 
external surface to the external pterygoid muscle. This plate forms the inner 
boundary of the zygomatic fossa, and the outer boundary of the pterygoid fossa, 
which lies between and behind the two plates. The interned pterygoid plate, 
longer and narrower than the external, forms the outer boundary of the posterior 
naris, where it is partly covered by the sphenoidal process of the palate-bone. 
From the upper end of the internal surface on each side a thin plate, the vaginal 
process, projects inward to articulate with the ala of the vomer, and in front with 
the sphenoidal process of the palate, the latter converting a groove beneath the 
base of the vaginal process into the pterygo-palatine canal. Posteriorly at the 
base of the internal plate is the small pterygoid tubercle, between which and 
the lingula is the Vidian canal, and below which is the shallow scaphoid fossa, 
in which the tensor palati muscle arises. The posterior border is prolonged below 
into the slender, hamular (“ hook-like ”) process, grooved externally above for the 
passage of the tendon of the tensor palati muscle. It is often to be felt behind and 
within the last upper molar tooth. In front the two plates are joined above, and 
form a smooth triangular surface, which makes the back Avail of the spheno-maxil- 
lary fossa, and presents superiorly the anterior orifice of the Vidian canal. Below, 
the two plates are separated in front by the pterygoid, notch, which is occupied by 
the pyramidal process of the palate-bone. The cartilage of the Eustachian tube is 
attached and supported along the hind, inner, and upper part of the internal plate. 
Articulations.—The sphenoid articulates with all the other bones of the cra- 
nium, which it binds firmly together, and with five of the facial bones—viz., two 
malar, two palate, and the vomer, and sometimes one or both superior maxillae. 
T arieties. The ligaments normally connecting the clinoid processes may 
become ossified. The foramen of Vesalius, for an emissary vein, is sometimes 
present internal to the foramen ovale. 
Ossification occurs in cartilage from tAvelve centres in tAvo divisions, a pre- 
and a post-sphenoid, which join at the olivary eminence, and are distinct in 
many animals. The sphenoidal sinuses begin to hollow out the body in the 
sixth year, before which they are confined to the sphenoidal turbinate bones, 
which develop separately in cartilage. 
THE ETHMOID BONE. 
The ethmoid or sieve-hone (Figs. 199-201) is roughly cuboidal, and projects 
downward from the ethmoidal notch of the frontal bone between the orbits to form 
part ot the orbits, nasal fossae, and base ot the cra- 
nium. It is very light, being largely composed of 
cavities bounded by thin walls. It consists of a ver- 
tical and a horizontal plate, and of two lateral masses, 
the last suspended from the margins of the horizontal 
plate. 
The vertical plate forms the upper third of the 
median (though often deflected) septum of the nose, 
and is grooved for the olfactory nerves. It projects 
into the cranial cavity above the horizontal plate as 
the median triangular crista galli (“ crest of the cock ”). 
This is most prominent in front, and along its thin 
posterior border it attaches the falx cerebri. In front 
it divides into two lateral ahc, which articulate with 
the frontal, and usually complete the foramen caecum. 
The vortical plate articulates in front with the nasal 
CRIBRIFORM 
PLATE 
Pig. 199—Diagram of the eth- 
moid bone in transverse, vertical 
section. (Testut.) 
spine of the frontal and the crest of the nasal bones, below and in front with the 
triangular septal cartilage, below and behind with the vomer, and behind with 
the crest of the sphenoid. 180 
THE BONES. 
The horizontal or cribriform plate is so named from a number of perforations 
arranged in three rows, of which those in the inner and outer rows are the larger 
and transmit the olfactory nerves to the inner and outer walls of the nasal fossae. 
This plate forms the depressed olfactory groove of the anterior cranial fossa, which 
lodges the olfactory bulbs on either side of the crista galli. On each side of the 
fore part of the latter is a longitudinal slit for the nasal branch of the fifth nerve. 
The lateral masses or labyrinths contain a number of irregular, thin-walled 
ethmoidal cells between their two lateral walls. The thin, smooth, oblong outer 
wall forms most of the inner wall of the orbit, and is called the os planum 
(“ smooth bone ”) or orbital plate. The borders of this plate and of the lateral 
mass articulate in front with the lachrymal, below with the superior maxilla and 
palate-bones, behind with the sphenoid and sphenoidal turbinate bones, and above 
with the orbital plate of the frontal. The latter articulation completes the two 
horizontal, transverse grooves in each bone into the anterior and posterior eth- 
moidal canals. These articulations (together with that of the nasal process of the 
maxilla with the fore part of the lateral mass internally) close the exposed half- 
cells of the ethmoid. The ethmoidal cells are lined by a continuation of the nasal 
VERTICAL PLATE 
DART SHOWS COURSE 
OF INFUNDIBULUM. 
ETH MOI DAL 
CANALS 
-INFUNDI- 
BULUM, 
ORBITAL 
PLATE 
ETHMOIDAL 
CANALS 
UNCINATE 
PROCESS 
Fig. 200.—The ethmoid bone, seen from above. (Testnt.) 
CRIBRIFORM PLATE. 
Fig. 201.—The ethmoid bone, its left 
side. (Testut.) 
mucous membrane, and are divided by a transverse septum into an anterior and a 
posterior set. The anterior set opens into a sinuous canal, the infundibulum, 
which leads from the frontal sinuses to the middle meatus of the nose; the 
posterior cells open into the superior meatus. The cells are sometimes divided 
into posterior, middle, and anterior sets, the two latter opening together. The 
inner wall forms the upper part of the outer wall of the nasal fossa, and is grooved 
for olfactory nerves and blood-vessels. It consists of the superior and middle 
turbinate bones, which have attached upper borders, but are free and somewhat 
rolled outward inferiorly. They are continuous in front, but separated in the 
posterior half by a channel, the superior 'meatus of the nose, directed forward 
from the posterior border. The middle turbinate extends the length of the bone, 
and overhangs and bounds superiorly the middle meatus of the nose. From beneath 
the fore part of the os planum a long, thin lamina of bone, the uncinate (“ hook- 
like ”) process projects backward and downward in the outer wall of the middle 
meatus, where it articulates with the ethmoidal process of the inferior turbinate 
bone, and helps to close the inner wall of the antrum of the maxilla. 
Articulation occurs with thirteen bones—viz., the frontal and sphenoid of the 
cranium, and the vomer, two nasal, two lachrymal, two maxillae, two palate, 
and two inferior turbinate bones of the face. 
Ossification proceeds in cartilage from three centres—one in the perpendicular 
plate and one in each lateral mass. True bony ethmoidal cells do not appear 
until the third year. THE SUPERIOR MAXILLARY BONE. 
181 
THE BONES OF THE FACE 
THE MAXILLA, OR SUPERIOR MAXILLARY BONE. 
The maxilla or upper jaw-bone (Figs. 202-204) forms the largest part of the 
facial skeleton, including part of the floor and outer wall of the nasal fossa, the 
roof of the mouth, and the floor of the orbits, and in it are lodged the upper teeth, 
it comprises a central hollow body and four processes. Its shape is characteristic 
of man and of his food and the mode of employing it. Surgically, it is important 
from its many diseases. 
The Body.—The facial surface looks forward and outward, and presents a 
prominent ridge, due to the fang of the canine tooth, which separates two shallow 
depressions, the incisive fossa in front and the canine fossa behind. Above the 
NASAL 
/1 N FRAORBITAL 
—’ FORAMEN 
POSTERIOR DEN 
TAL CANALS 
NASAL NOTCH 
NASAL 
SPINE 
Fig. 202.—The right maxilla, outer surface. (Testut.) 
latter and just below the orbital margin is the infraorbital foramen, where the 
infraorbital nerve and artery emerge. The inner margin presents the deep nasal 
notch, attaching the soft parts of the nose. The lower edge of the notch is pro- 
longed forward internally into the anterior nasal spine. The convex posterior or 
/LACH RYMAL GROOVE 
ANTERIOR NASAL 
SPINE 
.POSTERIOR PALA- 
TINE GROOVE 
ANTERIOR PALA- 
TINE GROOVE / 
PALATINE 
PROCESS 
zygomatic surface is separated from the facial surface by a ridge ascending from 
the socket of the first molar tooth to the malar process. This surface forms the 
anterior boundary of the zygomatic fossa, and above and internally it bounds the 
spheno-maxillary fossa in front. Near its centre are the apertures of the two or 
more posterior dental canals for nerves and vessels of that name. The prominent 
Fig. 203.—The right maxilla, inner surface. (Testut.) 182 
THE BONES. 
posterior inferior angle is the tuberosity, which attaches a few fibres of the internal 
pterygoid, and articulates along its rough internal border with the tuberosity of 
the palate-bone. The nasal or internal surface forms the outer wall of the nasal 
fossa in the lower and middle meatuses, and presents in front a ridge, the inferior 
turbinate crest, which articulates with the inferior turbinate bone. Above and 
behind the surface is deficient, presenting the large irregular opening into the 
antrum. Above this opening there are one or two half cells, which complete as 
many ethmoidal cells. Behind it the surface is rough for articulation with the ver- 
tical plate of the palate-bone, except for a smooth groove directed downward and 
forward from the posterior border, which is completed by the palate-bone into the 
posterior palatine canal. The posterior border is separated from the pterygoid 
process of the sphenoid by the tuberosity of the palate-bone. Behind the nasal 
process and between it and this surface notice the lachrymal groove, which descends 
with a backward and a slight outward inclination. This is completed into a 
canal for the nasal duct by the lachrymal and inferior turbinate bones, and opens 
below into the inferior meatus. The smooth, triangular orbital or upper surface 
forms the floor of the orbit and the inner part of its lower margin. Internally 
it articulates from before backward with the lachrymal, ethmoid, and palate 
bones. At the anterior end of this border is the outer part of the upper orifice 
of the lachrymal groove. The free, smooth, postero-external margin bounds the 
spheno-maxillary fissure in front and internally, and presents about its middle 
the commencement of the infraorbital groove, which passes forward in the orbital 
surface to the canal and foramen of the same name. From the canal the middle 
and anterior dental canals, for nerves and vessels of the same name, run down- 
ward in the facial portion of the bone. The antero-external margin of this sur- 
face bounds the rough upper surface of the thick triangular malar process, which 
articulates with the malar bone. This process is continuous in front with the 
facial surface and behind with the zygomatic surface of the body. 
The nasal process is a triangular plate of bone which projects upward and 
slightly inward. It presents externally a smooth surface continuous with the 
facial surface of the body. The internal surface is crossed by the superior turbinate 
crest, which articulates with the middle turbinate bone. Above the crest it articu- 
lates with the ethmoid (closing its foremost cells), and below it this surface forms 
part of the outer nasal wall in the middle meatus. The serrated summit articulates 
with the frontal, the anterior border with the nasal, and the posterior border is 
marked by the lachrymal groove, which lodges the lachrymal sac. The sharp inter- 
nal border of this groove articulates with the lachrymal bone, while the smooth 
external border forms the inner margin of the orbit, the point of whose junction 
with the lower margin is marked by the lachrymal tubercle. The alveolar process 
is the thick, arched lower border of the bone, which contains the alveoli (“ little 
hollows”) or tooth-sockets, corresponding in shape and number to the roots of the 
eight teeth which occupy them. The palate process, projecting horizontally 
inward from the junction of the body and the alveolar process, articulates with 
its fellow of the opposite side to form the forward three-fourths of the hard 
palate, the upper surface of which belongs to the floor of the nose, the lower to 
the roof of the mouth. The upper transversely concave surface is smooth, while 
the lower vaulted surface is rough and marked at its lateral margin with a groove 
for the vessels and nerves passing forward from the posterior palatine canal. The 
posterior border articulates with the horizontal plate of the palate-bone, which 
completes the hard palate, while the median border joins with its fellow to form, 
superiorly, the vertical grooved nasal crest, which receives the vomer. In front 
of the vomer this crest, suddenly becoming much higher, is called the incisor 
crest, which supports the septal cartilage of the nose, and ends in front in the 
nasal spine. On each side of this crest, where it joins the upper surface, is seen 
the incisor or Stenson’s foramen, for the terminal branches of the posterior pal- 
atine arteries. These two foramina converge downward and forward, and open 
on the roof of the mouth into a single canal, the anterior palatine fossa, common THE PALATE-BONE. 
183 
to them and the two foramina of Scarpa, which are placed in front of and behind 
the former in the median suture, and transmit the naso-palatine nerves. In young 
bones the premaxillary suture extends from this fossa on each side to, but not 
through, the outer alveolar border, internal to the canine socket. The part in 
front of this suture represents the premaxillary hone of the lower animals, and 
includes the incisor teeth. It is separately formed, and sometimes remains sep- 
arate on one or both sides in cases of cleft-palate. 
The antrum of Highmore, or maxillary sinus, is a pyramidal air-chamber occu- 
pying the body of the bone. Its thin walls correspond to the surfaces of the 
body. The apex corresponds to the malar 
process, and the base to the nasal surface, 
the large opening in which is partly closed 
by the palate-bone behind, the inferior tur- 
binate bone inferiorly, and the uncinate pro- 
cess of the ethmoid and the lachrymal above 
and in front. It is made still smaller by 
the mucous membrane, and opens into the 
middle meatus of the nose by one or some- 
times two apertures. Along the lower angle 
the roots of the first two molars often project 
into the cavity. The antrum may some- 
times be partly, rarely completely, sub- 
divided. 
SPHENOPALA- 
TINE FORAMEN 
Articulations.—The maxilla articulates 
with its fellow and with the nasal, frontal, 
lachrymal, ethmoid, palate, vomer, inferior 
turbinate, and malar bones, and sometimes 
with the sphenoid. 
Ossification occurs early in membrane 
from four centres, and some of the lines 
Fig. 204.—The maxillary sinus and the inner 
wall of the orhit. The apex of the sinus and 
the outer wall of the orbit have been removed. 
(Testut.) 
between the parts are often to be seen in the young adult bone, especially in the 
floor of the orbit. The antrum appears in foetal life. 
THE PALATE-BONE. 
The palate-hone (Figs. 205, 206) is L-shaped, and is wedged in between the 
maxilla and the pterygoid process of the sphenoid, forming the back part of the 
hard palate, of the lateral wall of the nose, and of the floor of the orbit. It has 
a horizontal and a vertical plate, united at a right angle. The tuberosity projects 
backward and outward from the rear of this angle, and the vertical plate is 
surmounted by two processes, the orbital and sphenoidal. 
The horizontal plate completes the hard palate, and presents a smooth, concave 
upper surface and a rough lower surface. The latter presents behind a transverse 
ridge which attaches the aponeurosis of the soft palate, connected with the tensor 
palati muscle. The anterior border articulates with the palate process of the 
maxilla ; the internal border articulates with its fellow, forming the continuation 
of the nasal crest which supports the vomer, and ends at the posterior border 
in the posterior nasal spine. The free and sharp posterior border bounds the 
posterior nares inferiorly, and attaches the soft palate. 
The vertical plate is thin and presents a rough outer surface, which, applied 
against the maxilla, completes the groove near its hind border into the posterior 
palatine canal. Behind the groove is a smooth surface superiorly, forming part 
of the inner wall of the spheno-maxillary fossa, below which the surface is rough 
for articulation with the pterygoid process and the maxilla successively. In h’ont 
this surface overlaps the opening of the antrum by a thin projection, the maxil- 
lary process. The inner or nasal surface presents the hind part of the inferior 
and middle meatuses of the nose, each limited above by a transverse ridge or crest, 184 
THE BONES. 
articulating with the inferior and middle turbinate bones respectively. Above the 
upper ridge the two processes ascend, separated by the deep spheno-palatine notch, 
which is converted into a foramen of the same name by articulation with the 
sphenoid bone. This foramen connects the spheno-maxillary and nasal fossae, 
SPHEN. 
PROCESS 
/S PH E NO - PA LA- 
TIN E NOTCH 
PROCESS 
INF. TURB. 
CREST i 
NASAL 
CREST 
TUBER- 
OSITY 
PTERYGOID FOSSA 
Fig. 205.—The two palate-hones in their natural posi- 
tion, dorsal view. (Testut.) 
Fig. 206.—The right palate-bone, 
inner surface. (Testut.) 
and transmits the spheno-palatine artery and nerve. At the lower end of each 
process internally is a grooved surface entering into the superior meatus. 
The five-sided orbital process surmounts the anterior border of the vertical 
plate, and articulates with the maxilla in front, the sphenoid behind, and the 
ethmoid internally. The ethmoidal cells or the sphenoidal sinus may extend into 
its hollow body. Of the two free surfaces the superior forms the rear angle of 
the orbital floor, and the external looks into the spheno-maxillary fossa, while the 
border between them bounds the spheno-maxillary fissure internally at its hind 
end. The sphenoidal process curves upward and inward, and articulates exter- 
nally and superiorly with the base of the internal pterygoid plate and of the 
sphenoidal body, completing with the former the pterygo-palatine canal. At its 
lower part, in front, a small surface looks outward into the spheno-maxillary 
fossa. The inner surface looks into the nasal fossa, and above, where it touches 
the ala of the vomer, forms a part of its roof. The tuberosity or pyramidal process 
is wedged in between the tuberosity of the maxilla and the pterygoid process. 
It presents externally a small free surface in the zygomatic fossa. Posteriorly it 
fills the pterygoid notch, and completes the pterygoid fossa by a smooth triangular 
surface lying between two rough grooves, which articulate with the anterior bor- 
ders of the two pterygoid plates. Inferiorly, near its junction with the horizontal 
plate, with which it is continuous, are seen the lower orifices of the accessory, 
posterior, and external palatine canals. 
Articulation.—The palate articulates with its fellow, the vomer, maxilla, infe- 
rior turbinate, sphenoid, and ethmoid. 
Ossification proceeds from a single centre in the membrane of the nasal capsule. 
THE VOMER. 
The vomer (“ ploughshare ”) (Fig. 207) is a thin, irregular quadrilateral plate 
forming the lower and back part of the nasal septum. It is usually deviated 
from the vertical plane, most often to the left. Each lateral surface is covered 
with muco-periosteum, and presents a faint groove running downward and for- 
ward to conduct the naso-palatine nerve to Scarpa’s canal. The thick superior' 
border splits into two alee (“ wings ”), which embrace the rostrum of the sphenoid, 
while their margins meet the vaginal processes of the sphenoid and the sphenoidal THE NASAL BONE. 
185 
processes of the palate-bones. The oblique anterior border joins the vertical plate 
of the ethmoid above, and below it is grooved for the septal cartilage. The infe- 
rior border is received into the groove of the nasal crest of the maxillae and palate- 
ANTERIOR PALA- 
TINE GROOVE 
HARD PALATE 
Fig. 207.—Sagittal section of face, a little to the left of the middle line, showing the vomer and its relations. 
(Testut.) 
bones. The truncated anterior angle fits in behind the incisor crest of the maxillae. 
The thin, free posterior border separates the two posterior nares. 
Ossification proceeds from a single centre in membrane, and forms two lamellae, 
which cause the absorption of the intervening cartilage. 
THE INFERIOR TURBINATE BONE. 
Each inferior turbinate hone (Figs. 208, 223) is a scroll-like lamella which 
separates the middle from the inferior meatus of the nasal fossa, and is attached 
above to the outer wall of the nose, but is free below. Its convex inner surface, 
marked by pits and longitudinal grooves for vessels, ends below in the convex, 
thickened free border, which is rolled upon itself. The attached upper margin 
articulates in front with the inferior turbinate 
crest of the maxilla, behind which it rises ab- 
ruptly into the lachrymal process, which articu- 
lates with the lachrymal bone and helps to close 
the lachrymal canal. Behind this is the max- 
illary process, bent downward and closing the 
lower part of the opening of the antrum. Above 
LACHRYMAL 
PROCESS 
ETHMOID 
PROCESS 
CFRONT 
END 
and behind the latter process the ethmoidal pro- 
cess rises to join the uncinate process of the 
Fig. 208—Right inferior turbinate bone, 
external surface. (Testut.) 
ethmoid. The posterior part of this margin is attached to the inferior turbinate 
crest of the palate-bone. The posterior angle is sharp, the anterior more blunt. 
The outer surface is concave and grooved. 
Ossification.—This bone ossifies from a single centre in cartilage, and may be 
regarded as a detached portion of the ethmoid. 
The two oblong nasal bones (Fig. 209) form the bridge of the nose. The 
facial surface of each is vertically concave above and convex below, and trans- 
versely convex. The posterior or nasal surface, transversely concave, is rough 
THE NASAL BONE. 186 
THE BONES. 
above, where it rests upon the nasal process of the frontal. Below it forms part 
of the roof of the nose, and presents a longitudinal groove for the nasal nerve. 
This groove ends in a small notch near the inner end of the 
thin lower border, which attaches the lateral nasal cartilage. 
The short, thick upper border articulates with the nasal notch 
of the frontal. The long outer border articulates with the nasal 
process of the maxilla. The inner border, thicker above, meets 
that of its fellow, with which it is prolonged backward into a 
median crest, which from above downward rests upon the nasal 
spine of the frontal, the vertical plate of the ethmoid, and the 
septal cartilage of the nose. 
Ossification proceeds from a single centre in membrane 
overlying cartilage, which is absorbed. At birth the bone is 
relatively broad. The shape of the nose depends largely 
Fig. 209. Nasal 
bones, viewed from 
before. (Testut.) 
upon that of these bones 
The lachrymal hone (os unguis), u nail-bone” (Figs. 210, 211), is a thin quadri- 
lateral scale of bone forming the front of the inner wall of the orbit. Its external 
or orbital surface presents a larger, flat hind or orbital part, and a smaller grooved 
fore part, forming the lachrymal sulcus or groove for the lachrymal sac. These por- 
tions are separated by a sharp vertical ridge, the lachrymal crest, which is prolonged 
forward at its lower end into the hamulus, which often articulates with the lachrymal 
tubercle of the maxilla, and bounds the orifice of the lachrymal canal externally. 
THE LACHRYMAL BONE. 
HAMULUS 
TURBINAL 
PROCESS 
Fig. 210.—Right lachrymal 
bone, outer surface. (Testut.) 
Fig. 211.—Right lachrymal 
bone, inner surface. (Testut.) 
The internal surface closes some of the front ethmoidal cells above, and below 
looks into the middle meatus of the nose. The anterior border articulates with the 
nasal process of the maxilla, the superior with the internal angular process of the 
frontal, and the posterior with the orbital plate of the ethmoid. The inferior 
border behind the crest joins the orbital plate of the maxilla, and in front it is 
prolonged downward as the descending or turbinal process, which joins the lachry- 
mal process of the inferior turbinate bone to complete the lachrymal canal. 
The lachrymal ossifies from a single centre in membrane, and is a diminishing 
element. 
THE MALAR BONE. 
The quadrangular malar bone (Figs. 212, 213) forms the prominence of the 
cheek and helps to separate the orbit from the temporal fossa. The outer surface 
is convex, and presents near its centre the orifice of the malar canal. The concave 
inner surface looks into the temporal fossa above, the zygomatic fossa below, and 
articulates in front by a rough triangular surface with the malar process of the 
maxilla. The four angles are directed vertically and horizontally. The prominent, 
serrated upper angle or frontal process articulates with the external angular process 
of the frontal, and the posterior angle or zygomatic process is bevelled above, and 
articulates with the end of the zygoma. The sinuous temporal border between these 
two angles is continuous with the upper edge of the zygoma below and the tern- THE MANDIBLE, OR INFERIOR MAXILLARY BONE. 
187 
poral ridge above, and attaches the temporal fascia. The posterior inferior or mas- 
seteric border completes the lower edge of the zygomatic arch and attaches some 
fibres of the masseter. The antero-inferior or maxillary border, the inferior angle, 
FRONTAL PROCESS 
FRONTAL 
PROCESS 
ZYGOMATIC ( 
PROCESS'^ 
PROCESS 
ZYGOMATIC 
ZYGOMATIC 
PROCESS 
Fig. 213.—Right malar bone, inner surface. (Testut.) 
Fig. 212.—Right malar bone, outer surface. (Testut.) 
and the anterior angle or maxillary process articulate with the maxilla. The 
antero-superior or orbital border is curved to form the outer margin and the outer 
half of the lower margin of the orbit. From this border the curved, triangular 
orbital process projects backward and inward, and forms the anterior boundary 
of the temporal fossa and the fore part of the outer wall and floor of the orbit. 
It articulates above with the frontal, and behind with the great wing of the 
sphenoid and the orbital plate of the maxilla. Between the articulations with 
the latter two bones there is usually a free margin bounding the spheno-maxillary 
fissure in front. The temporal and malar canals, for the temporo-malar branches 
of the fifth nerve, are seen on the orbital surface. 
Ossification proceeds in membrane from two or sometimes three centres, and 
the adult bone is occasionally divided by a horizontal suture into two unequal 
parts. 
THE MANDIBLE, OR INFERIOR MAXILLARY BONE. 
The lower jaw-bone (Figs. 214, 215) is a large, strong, horseshoe-shaped bone, 
forming the lower third of the facial skeleton, and articulating by means of a 
pair of condyles with the glenoid fossse of the temporal bones. It consists of a 
nearly horizontal body in front and two posterior vertical portions or rami. 
Fig. 214.—The mandible, viewed from the right and a little in front. (Testut.) 
Cental 
PROTUBERANCE 
The body consists of two symmetrical, lateral halves, whose symphysis 
(“ together-growth ”) or union in the middle line is marked on the external sur- 
face by a faint vertical ridge which expands below into the triangular mental 
protuberance or chin. The centre of the base of the protuberance may be 188 
THE BONES. 
slightly depressed, and from its prominent lateral angles, or mental (“ chin ”) 
tubercles, the rather faint external oblique line extends backward and upward to 
become continuous with the anterior border of the coronoid process. Below the 
incisor teeth on each side is the incisor fossa. Midway between the upper and 
lower borders and in line with the second bicuspid tooth, or the interval between 
the two bicuspids, is the mental foramen, transmitting the mental nerve and vessels 
from the dental canal. The internal surface presents at the symphysis, superiorly, 
a linear groove, ending below in a small foramen, below which are two pairs of 
genial (“ chin ”) tubercles, sometimes fused into a single median ridge. The upper 
pair attaches the geuio-hyoglossi muscles, and a small median ridge, attaching 
the genio-hyoid muscles, usually takes the place of the lower pair. Below and 
on each side of this, and close to the lower border, is a rough depression for the 
anterior belly of the digastric muscle. Beginning above the latter and at the 
CON DYLE 
CORO. PROC. 
INFERIOR DEN- 
TAL FORAMEN 
GENIAL 
TUBERCLES/ 
Fig. 215.—The right half of the mandible, inner surface. (Testut.) 
side of the lower genial tubercle on each half of the bone, the internal oblique line 
or mylo-hyoid ridge passes backward and upward to the ramus. This attaches the 
mylo-hyoid muscle, and, at the posterior end, the superior constrictor muscle and 
the pterygo-maxillary ligament. Above the line, on each side of the symphysis, 
is the shallow sublingual fossa for the sublingual gland ; and below it, at the 
side, is the submaxillary fossa for the submaxillary gland. The superior or alveolar 
border on each side presents the sockets for the roots of eight teeth, and exter- 
nally attaches the buccinator as far forward as the first molar. The inferior 
border, thick, smooth, and rounded, projects beyond the upper, and is grooved 
for the facial artery near its junction with the ramus. 
The ramus is quadrilateral and thinner than the body. The masseter mus- 
cle is inserted on its external surface. On the internal surface, about its mid- 
dle, is the inferior dental foramen, leading to the inferior dental canal for the 
inferior dental vessels and nerves. This canal is nearer the inner surface behind 
and the outer in front where it connects with the mental foramen. It commu- 
nicates by a series of fine channels with the bottom of each tooth-socket. The 
front and inner edge of the foramen is sharp and prominent, forming the lingula, 
which attaches the spheno-mandibular or long internal lateral ligament of the 
jaw. Behind the lingula and below the foramen the mylo-hyoid groove (some- 
times a canal at first) starts in its downward and forward course beneath the 
mylo-hyoid ridge, and lodges the mylo-hyoid nerve and vessels. Between this 
groove and the angle the internal pterygoid muscle is inserted on a rough trian- 
gular space. The lower border, continuous with that of the body, meets the 
posterior border at the angle of the jaw. This is usually slightly everted, and 
attaches behind the stylo-mandibular fold of fascia. The sharp, concave upper 
border, known as the sigmoid notch, separates the two processes, and is crossed by 
the masseteric nerve and artery. The hind process, or condyle, surmounts the 
posterior border on a constricted portion, or neck, in front of which, internally, THE HYOID BONE. 
189 
is a depression for the insertion of the external pterygoid muscle. The condyle 
is convex and transversely elongated on an axis which, prolonged, would meet 
that of its fellow near the front of the foramen magnum. Its prominent outer 
end, beyond the articular surface, forms a tubercle, to which the external lateral 
ligament is attached. The thin coronoid 'process tapers upward and outward from 
the anterior border, and to its tip, borders, and internal surface the temporal 
muscle is attached. The inner surface presents a ridge, continuous below with 
the internal oblique line and the inner alveolar edge. Between this ridge and the 
anterior border is a groove for the insertion of the temporal muscle above, and, 
for a short distance, for the buccinator below. 
The changes according to age (Figs. 216, 217) are so ordered that the upper 
and lower gums, or teeth, as the case may be, meet in biting. Thus, at birth the 
angle is about 175°, the body is shallow and consists mostly of alveolar process, and 
the mental foramen is near the 
lower border. At about four 
years of age, after the first 
dentition, the angle is reduced 
to 140°, as the body plus the 
teeth is much deeper. In adult 
life the depth of the body has 
Fig. 216.—The mandible in infancy. (Tes 
tut.) 
Fig. 217.—The mandible in old age. (Testut.) 
so increased below, in the basal part, that the foramen is midwav between the 
borders, and the angle is 120° to 110°, or even less. In old age the alveoli are 
absorbed, the foramen is near the upper border, the body is basilar, and the 
angle is increased to 140° or so, thus allowing the gums to meet. This throws 
the chin forward, and the pressure of the tightened lips presses back the upper 
border of the bone in front. 
Ossification proceeds at a very early period from four to six centres on each 
side. The part from the symphysis to the mental foramen is ossified in the ante- 
rior end of Meckel's cartilage, the condyle and angle from separate centres in 
cartilage, and the rest in membrane. At birth the two halves are united by 
fibrous tissue. 
The hyoid (“like Greek letter upsilon”) or lingual hone (Fig. 218) is a small 
U-shaped bone which maybe felt at the base of the tongue, between the chin and 
the thyroid cartilage. It has a body and two pairs of cornua. 
THE HYOID BONE. 
The oblong body has a smooth, con- 
cave posterior surface, looking backward 
and downward toward the epiglottis. Its 
convex anterior surface, looking upward 
and forward, is divided by a transverse 
and sometimes a median vertical ridge 
into depressions for muscular attachment. 
The superior border attaches the thyro- 
hyoid membrane. 
The great cornua taper backward and 
SMALL CORNU 
Fig. 218.—The hyoid bone. (F. H. G.) 
upward from the sides of the body, ending in rounded tubercles to which the 
thyro-hyoid ligaments are attached. The cornua are flattened above and afford 190 
THE BONES. 
attachment to muscles. The small cornua are small conical pieces of bone, often 
partly, and sometimes wholly, cartilaginous, which project upward and backward 
from the junction of the great cornua and the body. Their extremities attach 
the stylo-hyoid ligaments, which suspend the hyoid from the styloid processes of 
the temporal bones. 
Ossification occurs in the cartilage of the second visceral arch, continuous with 
the styloid process. There is a centre for each cornu, and for each half of the 
body. The synchondrosis of the great cornu usually ossifies after middle life. 
The synovial articulation of the small cornu seldom ankyloses. 
THE SKULL AS A WHOLE. 
The Sutures. 
The sutures are the closely-fitted articulations of the uneven edges of the bones 
of the skull, in which the bones are separated only by a fibrous suture membrane, 
continuous with the periosteum and dura, except in the two synchondroses of the 
jugular and basilar portions of the occipital bone, at the base of the skull, where 
cartilage intervenes until it is ossified in adult life. The sutures allow the rapid 
growth of the skull in early life, diminish shocks, and, by being alternately 
bevelled on each side, bind the bones so firmly together that dislocation is 
next to impossible. Many of them are often, but not always, obliterated by 
ossification in adult life. The time when this commences is very variable, but it 
usually begins where they last came together—i. e., near the posterior, anterior, or 
antero-lateral fontanelles. 
Though the sutures arc best named from the bones which form them, those 
around the parietal bones have received special names from their shape, direction, 
etc., as the sagittal (interparietal), the coronal (fronto-parietal), the lambdoidal 
(occipito-parietal), and the squamous (squamo-parietal). 
The fontanelles (“ little springs ”) are unossified, membranous spaces which 
exist before, at, and for a time after birth at the angles of the parietal bone. 
Their existence and position are due to the fact that, while the bones are quadri- 
lateral, ossification proceeds radially or circularly, so that the angles are the last 
to ossify. The larger, diamond-shaped anterior fontanelle is an important land- 
mark at parturition. It serves for a safety-valve for the rapidly varying intra- 
cranial pressure of early infancy, and closes during the second year. The anterior 
and posterior lateral fontanelles are closed in foetal life. The posterior fontanelle 
is often filled up before birth, but the bones are then movable upon each other, 
and the triangle of their converging margins may be felt as a landmark during 
parturition. Wormian bones often assist in the closure of the lateral and 
posterior fontanelles. 
Wormian bones are small, irregular ossicles from supernumerary ossific centres 
whicli are found in varying numbers in the sutures, especially in those about the 
parietal bones, and chiefly near the fontanelles. They are most numerous and 
largest in the lambdoid suture, but must be distinguished from the interparietal 
portion of the occipital bone when it exists as a separate bone. A small ossicle, 
the epipteric (“upon the wing”) bone, is found in most skulls in each anterior 
lateral fontanelle up to the fifteenth year, after which it usually joins the great 
wing of the sphenoid. 
The skull is bilaterally symmetrical. The superior region includes the smooth 
convex surface. It is covered by the occipito-frontalis muscle and aponeurosis and 
the scalp, which extends from the supraorbital margins in front to the superior 
curved lines of the occipital bone behind and between the superior temporal lines 
laterally. The skull, viewed from above, is broader behind than in front, and is oval 
The Exterior of the Skull THE EXTERIOR OF THE SKULL. 
191 
in outline, with slight projections at the frontal and parietal eminences and at the 
occipital protuberance. At the meeting of the sagittal and coronal sutures is the 
bregma, at the site of the anterior fontanelle ; and the lambda is where the sagittal 
and lambdoid sutures meet, at the site of the posterior fontanelle. The occipital 
protuberance is known as the inion (“occiput ”). Except in very broad skulls the 
zygomatic arches are visible from above. 
The lateral or temporal region (Figs. 219, 220) presents the temporal fossa, 
formed by the temporal, parietal, sphenoid, frontal, and malar bones, and occu- 
.BREGMA 
GLABELLA, 
n asionJ 
•OBELI ON 
LAMBDA 
ANTERIOR NASA 
SPINE 
PROSTHION 
Pinion 
gnathionl 
* GOIMION 
Fig. 219.—Skull, viewed from the left side, showing the principal craniometric points. 
pied by the temporal muscle. It is limited below by the zygomatic arch exter- 
nally and the pterygoid ridge of the sphenoid internally. Above it is bounded 
by the temporal ridge, which, starting at the external angular process of the frontal 
bone, arches upward and backward, and then downward. Near the coronal suture 
it usually divides into a superior and an inferior ridge. The latter limits the origin 
of the temporal muscle, and is continuous behind with the supramastoid crest and 
the posterior root of the zygoma. The former, less constant and not as marked, 
attaches the temporal fascia and arches down to the mastoid process near the 
asterion (“ starry ”) at the site of the posterior lateral fontanelle. The pterion 
(“wing”), at the site of the anterior lateral fontanelle, is where the parietal, 
frontal, sphenoid, and temporal bones come together. The temporal fossa com- 
municates with the zygomatic fossa through the opening bounded externally by 
the zygomatic arch. 
The zygomatic fossa is bounded in front by the zygomatic surface of the max- 
illa, internally by the external pterygoid plate, externally by the zygomatic arch 
and ramus of the jaw, and superiorly by a small triangular surface on the 
squamosal and by the great wing of the sphenoid internal to the pterygoid ridge. 
Posteriorly it is limited by a line drawn from the sphenoidal spine to the zygo- 
matic tubercle. It is occupied by the pterygoid and temporal muscles and the 
coronoid process of the lower jaw. Internally, between its anterior and internal 
boundaries, is the vertical pterygo-maxillary fissure, between the maxilla and the 
anterior border of the external pterygoid plate. This connects the zygomatic with 
the spheno-maxillary fossa. Above and at right angles to the pterygo-maxillary 192 
THE BONES. 
fissure is the spheno-maxillary fissure, which connects the upper part of the zygo- 
matic and of the spheno-maxillary fossae with the orbit. This fissure lies nearly 
horizontally between the free margins of the orbital surfaces of the maxilla and 
the palate-bone internally and the sphenoid externally. In front it is usually 
ARROW IN OPTIC 
/ FORAMEN 
INFUNDIBULUM 
LACHRYMAL CAN AL 
EXTERNAL AUDI- 
TORY CANAL 
SPHENO-PALA- 
TINE FORAMEN 
MASTOID 
CELLS A 
VIDIAN CANAL- 
limited by the malar bone, though the maxilla and sphenoid may articulate and 
Fig. 220—The bony sinuses of the head. (Testut.) 
exclude it 
The spheno-maxillary fossa, shaped like an inverted pyramid, is a small space 
between the maxilla and the root of the pterygoid process. It is bounded in 
front by the upper and inner part of the zygomatic surface of the maxilla, 
internally by the vertical plate and the orbital and sphenoidal processes of 
the palate-bone, behind by the roots of the pterygoid process and the lower 
part of the anterior surface of the great wing of the sphenoid. The apex 
leads into the posterior palatine canal, the base into the back of the orbit 
through the hind part of the spheno-maxillary fissure. Internally the spheno- 
palatine foramen connects it with the nasal fossa, and behind are seen the foramen 
rotundum, Vidian canal, and pterygo-palatine canal (in the order named, from 
above and without, downward and inward.) The fossa contains Meckel’s gan- 
glion, with its roots and branches, and the terminal branches of the internal 
maxillary artery enclosed in a mass of fat. 
The lateral region presents postero-inferiorly the external auditory meatus, 
nearly in the same vertical transverse plane with the bregma, and behind this 
the mastoid process, with the variable mastoid foramen behind and above it. 
The base of the skull externally (Fig. 221) from the incisor teeth to the exter- 
nal occipital protuberance is very irregular, and may be studied in three divisions. 
The anterior or palate division includes the hard, palate, formed by the palate 
processes of the maxillse and the palate-bones, and bounded laterally and in front 
by the alveolar arch. Medially in front notice the anterior palatine fossa, into 
which four foramina open, and from which, in young skulls, the suture separating 
the premaxillary bone runs to the outer side of each lateral incisor tooth. At the 
posterior angles are the lower openings of the posterior palatine canals, from each 
of which a groove runs forward in the angle between the palate and the alveolar 
arch for the anterior palatine nerve and the posterior palatine vessels. The 
hamular processes are seen at the postero-lateral limits of the hard palate, behind 
and internal to the last molar teeth. Between these and the posterior palatine 
canal are the openings of the accessory and external palatine canals. 
The middle or suheranial division extends back to a line joining the tips of the 
mastoid processes. It slopes upward and forward from behind, and is at a higher 
level than the anterior division. Between these two divisions are the following THE EXTERIOR OF THE SKULL. 
193 
vertically-placed structures : Mesially are the 'posterior nares, separated by the 
vomer, and bounded below by the horizontal plates of the palate-bones, laterally 
by the internal pterygoid plates, and above by the body of the sphenoid and the 
TEETH 
ANTERIOR PALA- 
TINE FORAMEN ' 
[IP A LATE DIVISION 
JSUBCRANIAL 
1 DIVISION 
STYLO-MASTOID] 
FORAMEN f 
‘SUBOCCIPITAL 
DIVISION 
Fig. 221.—Base of the skull, viewed from below. (Testut.) 
alee of the vomer. On each side is seen the pterygoid fossa, completed by the 
tuberosity of the palate-bone below, and lodging the internal pterygoid and tensor 
palati muscles. The latter muscle arises from the scaphoid fossa, a subdivision 
at the upper part of the pterygoid fossa. External to the pterygoid fossa is the 
zygomatic fossa, whose roof forms part of the base of the skull. 
The basilar process of the occipital bone and a small part of the body of the 
sphenoid occupy the median portion of the middle division, while laterally are 
the petrosals and a small portion of the great wings of the sphenoid, of the 
squamosals, and of the occipital bone. In the median line we notice the pharyn- 
geal tubercle and the front margin of the foramen magnum, termed the hasion. 
Laterally, in a nearly sagittal line, we notice from before backward the foramen 
ovale, the foramen spinosum, the opening of the bony and the groove for the 
cartilaginous Eustachian canal, the entrance of the carotid canal, and the jugular 
fossa and foramen. Internal to the latter is the anterior condylar foramen, and 
externally the stylo-mastoid, foramen. Between the extremities of the petrous 
portion of the temporal bone and of the basilar process of the occipital and 
the sphenoid we notice the foramen lacerum medium, filled by fibro-cartdage in 194 
THE BONES. 
the recent state. In an oblique line from the mastoid process to the external 
pterygoid plate we find projecting the styloid process, the vaginal process of the 
tympanic bone, and the spine of the sphenoid, the latter at the inner end of the 
Glaserian fissure. On this surface is seen laterally the eminentia articularis in 
front of the articular part of the glenoid fossa, which is separated by the Glaserian 
fissure from the non-articular portion on the outer surface of the tympanic plate, 
which lodges the parotid gland. The line limiting this region behind passes 
through the jugular processes of the occipital bone, and cuts the condyles a little 
behind their centre. 
The posterior or suboccipital division extends back to the superior curved lines 
of the occipital bone, divided into two lateral halves by the external occipital 
crest. It includes, mainly, rough lines and intervening spaces for muscular 
attachment. Behind the condyles are the posterior condylar fossce and foramina 
when the latter are present. Internal to and slightly behind the mastoid processes 
are the digastric and occipital grooves, for the digastric muscles and the occipital 
arteries respectively. 
FRONTAL 
SPHENO-MAXILLARY 
FISSURE 
INFRAORBITAL, 
FORAMEN 
Fig. 222.—Front view of the skull, the mandible having been removed. (Testut.) 
The anterior or facial region (Fig. 222) presents the nasion, in the centre of 
the naso-frontal suture, below the glabella. Below the nasion is the prominent 
bridge of the nose, formed by the nasal bones and the nasal processes of the 
maxillae. Below this is the anterior nasal aperture, which is shaped like an 
inverted heart and is often unsymmetrical. Its thin margins attach the nasal 
cartilages, and its lower border, projects forward as the anterior nasal spine. In the 
recent state it is bisected by the septal cartilages. Below this, on either side, are 
the incisor fossae. On either side of the bridge of the nose are the orbits, below 
which are the canine fossce, and external to the latter the prominences of the 
cheeks, formed by the malar bones. The teeth are a prominent feature of this 
region, and below them the body of the lower jaw completes the anterior surface. 
The three large foramina, supraorbital, infraorbital, and mental, each for a branch 
of one of the three divisions of the fifth nerve, lie in a nearly vertical line drawn 
through the second lower bicuspid tooth or the interval between the two lower 
bicuspids. The small malar canal is situated more laterally on the malar bone. 
The orbits are two irregularly quadrilateral, pyramidal fossae which lodge the 
eyeballs and their muscles, nerves, and vessels. The base of each, directed for- THE EXTEBIOR OF THE SKULL. 
195 
ward and slightly outward, is formed by the orbital margin, which is quadrilateral 
m shape with rounded angles. It is bounded above by the frontal, with the 
supraorbital notch or foramen at the junction of its inner and middle thirds ; 
internally by the nasal process of the maxilla; below by the infraorbital margins 
of the maxilla and malar, and externally by the malar bone. The concave roof 
of each orbit is formed by the orbital plate of the frontal and the small wing of 
the sphenoid. The outer walls of the orbits diverge so as to be almost at right 
angles with each other, and are formed by the orbital surfaces of the great wings 
of the sphenoid and the malar bones, the latter containing the temporal and 
malar canals. The floor, sloping from within downward and outward, is formed 
by the maxilla, with the orbital process of the palate-bone behind and a small 
part of the malar bone in front. The inner walls of the two cavities are nearly 
parallel, and are so continuous with the floors as to give a triangular shape to the 
orbit in some specimens, which is especially marked at birth. Each is formed, 
from before backward, by the nasal process of the maxilla, the lachrymal bone, 
the os planum of the ethmoid, and the body of the sphenoid. The apex of the 
orbit is at the inner extremity of the sphenoidal fissure, whose outer end separates 
the back part of the root and outer wall. The optic foramen lies at the back of 
the orbital roof, above and internal to the apex. In the angle between the roof 
and the inner wall lie the anterior and posterior ethmoidal foramina in the eth- 
moidal section of the transverse suture. The latter extends horizontally from 
one to the opposite external angular process of the frontal bone, along the margins 
of the orbital plates of the frontal and the nasal notch between. In the angle 
between the roof and the outer wall, in front, is the fossa for the lachrymal gland. 
Nt le angle between the outer wall and the floor in its posterior two-thirds is the 
spheno-maxillary fissure, communicating behind with the spheno-maxillary fossa, 
and in front with the zygomatic fossa. From its inner border the infraorbital 
gi oo ve passes forward in the floor of the orbit to the infraorbital canal. In the 
angle between the floor and the inner wall, and just behind the orbital margin, 
the lachrymal groove passes down into the lachrymal canal. A depression, some- 
times a tubercle, for the pulley of the superior oblique muscle is seen a little 
behind the supero-internal angle of the orbital margin. The orbits communicate 
with the cranial cavity and the nasal, spheno-maxillary, and zygomatic fossse. 
The nasal fossae (Fig. 223) are two irregular, oblong cavities of a truncated 
pyramidal shape. They are narrow transversely, especially above, but have a 
considerable diameter vertically and from before backward. They extend from 
the base of the skull to the upper surface of the hard palate, and open in front 
by the anterior nasal aperture, and behind into the pharynx by the posterior 
nares. They are situated one on each side of a median, vertical septum nasi or 
internal wall, formed by the vertical plate of the ethmoid, the vomer, the rostrum 
of the sphenoid, the nasal spine of the frontal, and the crests of the nasal, raax- 
illary, and palate bones. The angular interval between the vomer and the 
ethmoid plate in front is filled by the septal cartilage, which with the bony sep- 
tum is usually deflected to one side, most commonly to the left. The narrow 
roof of each fossa has a middle horizontal part formed by the cribriform plate of 
the ethmoid, with its many small apertures leading from the anterior cranial fossa, 
and an anterior and a posterior part sloping downward. The anterior slope is 
formed by the nasal bones and the nasal spine of the frontal. The posterior 
slope is formed by the body of the sphenoid, the sphenoidal turbinate bones, the 
alse of the vomer, and the sphenoidal processes of the palate-bones, and it contains 
the openings of the sphenoidal sinuses. The floor of each fossa, wider than the roof, 
is smooth and concave transversely, with a slight backward slope. It is formed by 
the palate processes of the maxilla and palate-bone, and presents in front, close to 
the septum, the incisor foramen (or canal), leading to the oral cavity. The exten- 
sive outer wall, sloped downward and outward, is formed by the nasal, maxillaiy, 
lachrymal, ethmoid, inferior turbinate, and palate bones, and the inner surface of 
the internal pterygoid plate. It presents three horizontal recesses or meatuses, 196 
THE BONES. 
overhung by three turbinate plates, of which the upper two belong to the ethmoid, 
and the lower is the inferior turbinate bone. 
The superior meatus, between the superior and inferior turbinate plates of the 
ethmoid, is very short, being limited to the posterior half of the fossa. It opens 
behind only, and into it open the posterior ethmoidal cells and the spheno-palatine 
OPENING OF SPHE- 
NOIDAL SINUS 
OPENING OF POS. 
ETHM. CELLS , 
OPENING OF MAX 
ILLARY SINUS 
SPHENO- 
PALATINE 
FORAMEN 
Fig 223.—The nasal fossae, viewed from the middle line. (Testut.) 
foramen, which connects it with the spheno-maxillary fossa. The middle meatus, 
between the inferior turbinate plate of the ethmoid and the inferior turbinate 
bonej is longer than the former. It opens both in front and behind, and into it 
open the maxillary sinus or antrum, and, by means of the infundibulum, the 
frontal sinus and the anterior ethmoidal cells. The inferior meatus, the longest 
and widest, also opens both in front and behind, and lies between the inferior 
turbinate bone and the floor of the nasal fossa. The nasal duct opens into it 
superiorly in front and connects it with the orbit. The nasal fossae thus com- 
municate by narrow passages with all the neighboring fossae and air-sinuses. The 
latter are hollow spaces within the maxilla, sphenoid, ethmoid, and frontal, 
already described in connection with those bones. With the exception of the 
antrum, which exists during foetal life, they originate during childhood, and all 
increase in size rapidly at puberty, and more slowly throughout adult life. 
The Interior of the Cranium. 
In a skull bisected horizontally or vertically notice the great proportionate 
size of the brain-cavity and the thickness and composition of its walls (Fig. 224). 
The latter consist of an outer and an inner table of compact bone and the inter- 
vening cancellous diploe (“fold”). The inner table, called the vitreous table from 
its hardness and brittleness, has a smooth, shining surface, marked with impres- 
sions for the convolutions of the brain and with grooves for blood-vessels. The 
skull-cap or calvaria averages one-fifth of an inch in thickness, but along certain 
ridges, and especially at the base, the thickness is much greater. Thinner areas 
exist in the cribriform plate of the ethmoid and the orbital plates of the frontal 
bone, where there is no diploe, and also in the lower occipital fossae, the squamous 
portions and glenoid fossae of the temporal bones. 
The calvaria or skull-cap consists of a vaulted dome, formed by the frontal 
and parietal bones and the interparietal portion of the occipital bone. Its inner 
surface presents in the median line the groove for the superior longitudinal sinus, 
ending in front in the frontal crest, and behind at the internal occipital protuber- 
ance. On either side of the groove are varying numbers of depresses for Pac- THE INTERIOR OF THE CRANIUM. 
197 
chionian bodies. Tins surface is marked by shallow cerebral impressions and 
grooves for meningeal vessels. The parietal foramen, for an emissary vein, is 
found, when present, at the side of the longitudinal sulcus near the postero- 
superior angle of the parietal bone. 
(Testut a®^ section of skull, a little to the left of the middle line, the inner surface of the right half. 
The base or floor of the cranial cavity (Fig. 225) presents three irregular fossae, 
termed anterior, middle, and posterior. 
The anterior fossa, on a higher level than the rest of the cranial floor, sup- 
ports the frontal lobes of the cerebrum, and is formed by the orbital plates of the 
frontal bone, the cribriform plate of the ethmoid, and the small wings and part 
of the body of the sphenoid. Over the orbits it is convex, but mesially it is 
depressed into the olfactory grooves for the olfactory bulbs on either side of the 
crista galli. In front of the crista is the foramen caecum. The floor of the 
olfactory grooves presents the numerous apertures of the cribriform plate for the 
olfactory nerves, mesially the slit-like foramen through which the nasal nerve 
passes into the nose, and laterally the internal openings of the anterior and poste- 
rior ethmoidal canals. 
The middle fossa, on a lower level than the anterior, presents a central isthmus 
and two lateral depressed parts. The small median part, formed by the sella 
turcica and the olivary eminence, is limited behind by the dorsum sellse, and in 
front by the anterior margin of the optic groove. It lodges the pituitary body 
and the optic commissure, and presents laterally the grooves for the carotid arteries 
from the foramina lacera media forward to the optic foramina. The lateral part 
on each side, limited behind by the superior border of the petrous portion of the 
temporal bone and in front by the free margin of the small wing of the sphenoid, 
is formed by the great wing of the sphenoid, the squamous portion, and the ante- 
rior surface of the petrous portion of the temporal. It lodges the temporal lobe 
of the cerebrum, and presents the following foramina from before backward : the 
sphenoidal fissure leading into the orbit; the foramen rotundum, leading into the 
spheno-maxillary fossa; the foramen ovale and the foramen spinosum, leading 
into the zygomatic fossa; the foramen lacerum medium, through which the carotid 
artery and plexus enter the cranial cavity ; and the hiatus Fallopii. Grooves for 
the middle meningeal artery pass from the foramen spinosum outward, upward, 198 
THE BONES. 
and backward on the great wing of the sphenoid, the squamous portion of the 
temporal, and the parietal bone. 
The posterior fossa, the deepest and largest, lodges the cerebellum, medulla 
oblongata, and pons, and is formed by the occipital bone, the petrous and mastoid 
portions of the temporal, the postero-inferior angle of the parietal, and the body 
of the sphenoid. Its anterior limits are the posterior limits of the middle fossa, 
and its posterior limits the grooves for the lateral sinuses, whose limiting ridges 
Fig. 225.—Base of the cranium, inner surface. (Testut.) 
attach the tentorium cerebelli. The foramen magnum occupies the centre, and 
external to it from within outward are seen the anterior condylar foramen, the 
jugular foramen, and the internal auditory meatus. Behind the jugular foramen 
is the opening of the posterior condylar foramen when present, and more exter- 
nally, in the sigmoid sulcus, is the more constant mastoid foramen. The grooves 
for the lateral sinuses pass outward from the internal occipital protuberance, 
usually cross the posterior inferior angle of the parietal bone, and thence bend 
sinuously down and in on the mastoid portion of the temporal bone, and onto the 
occipital bone, where they curve forward and end at the posterior division of the 
jugular foramina. The grooves for the inferior petrosal sinuses lie along the suture 
between the petrous portion of the temporal bone and the occipital, and end in 
the anterior division of the jugular foramina. The jugular foramen (foramen 
lacerum posterius) is usually unsyrnmetrical and of a somewhat pyriform shape. 
It is often divided into three compartments by two more or less marked con- GENERAL MORPHOLOG Y OF THE SKULL. 
199 
strictions. Through the largest and most posterior of these the lateral sinus 
passes into the internal jugular vein, and a small meningeal branch of the ascend- 
ing pharyngeal artery ascends ; the middle compartment transmits the glosso- 
pharyngeal, vagus, and spinal accessory nerves, and the anterior (sometimes 
completely separated) transmits the inferior petrosal sinus. 
General Morphology of the Skull. 
The cranial nerves pass through the skull in foramina occupying sutures or 
indicating points of union of two or more ossific centres. The foramen rotnn- 
dum is the only exception to this rule in the skull, and this is probably a separated 
segment of the sphenoidal fissure. The division into primary foramina, or those 
where the nerves pass through the dura (or original brain-case), and second- 
ary foramina, which are bony tunnels or canals not found in simpler skulls, 
though interesting, is not of sufficient importance for further description here. 
The remarkable constancy of the relation of the nerve foramina to the osseous 
elements has, with other facts, led to the conception of the vertebrate theory of 
the skull, which supposes that the skull is made up of a series of altered vertebrae, 
the neural arches of which have become greatly expanded to enclose the brain. 
Among the facts leading to this theory is the apparent construction of the skull in 
three parts: 1, the central or basilar, prolonging forward the vertebral axis 
around and beyond the end of the notochord in the craniofacial axis1; 2, the 
superior arches, three 2 in number, enclosing the brain ; 3, an equal number of 
inferior arches3 surrounding the visceral cavity, as represented by the nose, 
mouth, and pharynx. But, although from analogy we may imagine that the 
primitive human skull was segmented like the vertebral axis, there is no evidence 
of this, and for a number of other reasons the division of the head into vertebral 
segments is untrustworthy and fanciful. 
In the development of the skull three stages may be recognized : 1, the mem- 
branous stage, in which the brain is enclosed in a membrane representing the 
dura of the adult; 2, the chondral stage, in which the base and lower parts of 
the sides of the brain-case become cartilaginous, leaving the sides and roof mem- 
branous ; 3, the osseous stage, in which both cartilage and membrane become 
ossified from a large number of ossific centres, which first appear in the mem- 
brane. Along the sides and in front sense-capsules become invaginated, and 
indent the skull-wall in the ears, eyes, and nose. Some of the bones of the skull 
are developed wholly, others partly, in the basal cartilage and its forward pro- 
longation, the cartilaginous nasal capsule, or in the cartilaginous visceral arches ; 
while some are developed wholly, others partly, in the membrane of the cranial 
vault, in that around the nasal capsule (forming the greater part of the upper 
face), and in that connected with the visceral arches. 
The human skull, as compared with the skulls of lower vertebrates, is charac- 
terized by—l, its enormous brain-space and the corresponding expansion of the 
bones of the cranial vault; 2, the proportionally smaller development of the face, 
and especially of the jaws (bringing the face under the front of the cranium); 
3, its being balanced and supported on the vertebral column (adapting it to the 
erect position) by a sudden bend in the vertebro-cranial axis, and a great posterior 
development of the cranium, bringing the oecipito-vertebral articulation at the 
centre of gravity of the skull; 4, the downward opening of the nostrils and 
the diminished size of the nasal fossse, bringing the orbits nearer together, so as 
1 This is drawn from the basion to the anterior extremity of the sphenoid, and thence to the end 
of the anterior nasal spine (subnasal point), forming an angle, the cranio-facial angle. 
2 These consist of—l, the squamosal part of the occipital bone ;2, the great wings of the sphe- 
noid, the squamosals of the temporal bones, and the parietals; 3, the small wings of the sphenoid 
and the frontal bone. . , 
3 These include in the first arch the pterygoids, the palate, and the maxillary bones; in ie 
second, the mandible, the spheno-mandibular ligament, and the malleus of the ear; in the t ir , 
the styloid process, the hyoid bone, and the stylo-hyoid ligaments, plus the incus, and perhaps par 
of the malleus of the ear. 200 
THE BONES. 
to be nearly parallel internally and to look forward. The bones of the human 
skull are more completely consolidated, so that the total number is less than in 
the lower vertebrates. Thus the pro- and post-sphenoids, the interparietals, the 
squamosals, the styloids, the pterygoids, and the premaxillse are often separate 
bones, and the frontal bone and mandible are frequently divided into two halves 
in vertebrate skulls. 
The Various Forms of the Skull. 
The skull at birth is characterized by the small size of the face and the very 
large size of the cranium, the smallness of the base, the prominence of the 
parietal and frontal eminences, the absence of the mastoid processes, the diploe, 
the suture serrations, the impressions, grooves, and ridges, and by the existence 
of the fontanelles. The temporal squama and the great wings of the sphenoid 
do not extend far upward, and the glenoid fossae are quite flat and small. 
Variations with Age.—The skull grows very rapidly during the first seven 
years. During the first dentition the fontanelles close, the face enlarges, the jaws 
lengthen, and the zygoma projects. By the seventh year some parts, such as the 
circumference of the foramen magnum, the petrous portion of the temporal bones, 
the body of the sphenoid, and the cribiform plate, have attained their definitive 
size, while other parts are quite immature. Near the approach of puberty a 
second period of active growth begins, and results in the elongation of the face, 
due to the increased height of the nasal fossae, the expansion of the air-sinuses, 
the enlarged teeth of the second dentition, and the augmented height of the 
alveolar arches of the jaws. Ossification becomes completed, and the adult shape 
and size are attained. The capacity increases but little after thirteen years of 
age. In later years the muscular crests develop, the frontal region elongates, and 
the air-passages and cells expand, the latter process continuing in old age. In old 
age the skull undergoes atrophy, becoming thinner, lighter, and, often a little 
smaller by absorption on the outer surface. The air-cells expand as the capacity 
diminishes, and the face becomes smaller by absorption of the alveolar processes 
and the loss of the teeth, causing the upper jaw to retreat and the lower to project 
at the chin. 
Sexual Variations.—The male skull is larger, heavier, and of greater capacity 
(11 :10), especially in the frontal and occipital regions, than the female, and the 
ridges, occipital protuberance, mastoid processes, zygomatic arches, and frontal 
sinuses are more developed. The female skull preserves a look of immaturity in 
the smaller proportion of the face, the narrower and less prominent jaws, the 
prominence of the parietal eminences, and the smoothness of the surface. 
Race differences, except among three or more large general classes, are often 
so slight, taking averages, as to require accurate and uniform cranial measure- 
ment or craniometry for their determination. Of the measurements the most 
important are the following, with the data of the average European skulls for 
each : (1) The capacity, 1450 c.c., affording a convenient indication of the devel- 
opment of the brain. (2) The circumference, 52 cm., taken in a plane passing 
behind through the occipital point (or the point of the occipital bone in the 
median plane farthest removed from the glabella), and in front through the 
ophryon (or the middle of the line drawn across the narrowest part of the fore- 
head). (3) The length, 17 cm., from the ophryon to the occipital point. This 
is above the frontal sinus, and gives the length of the brain-case only, while the 
maximum length is between the glabella and the occipital point. (4) The maxi- 
mum breadth is the greatest breadth between the parietals; the breadth at the 
level of the zygomata is 12.5 cm. (5) The height from the basion to the bregma 
is nearly the same as the breadth. The craniofacial angle is about 96°. For 
the ready comparison of race-measurements the breadth and height are reduced 
. , , . -ti, , „ „ 100 X breadth or height 
to indexes by comjianson with the length as follows ; length * THE VARIOUS FORMS OF THE SKULL. 
201 
Furthermore, the shape of the transverse arch of the cranium, the fusion or 
complexity of the sutures, the degree of projection of the jaws (indicating an 
approach to, or a removal from, the animal type), the relation between the height 
and the width of the anterior nasal aperture (or nasal index), and of the base 
of the orbits (or orbital index), are subject to variation among different races. 
The facial angle (of Cloquet), which helps to determine the relative development 
of the face and the frontal part of the cranium, is that formed by two lines 
meeting in the median line at the alveolar border of the maxilla, and drawn, one 
from the most prominent median frontal point and the other from the middle of 
the external auditory meatus. Several other measurements for more accurate 
determination of the form of the cranium are in use, for which Broca’s or other 
works on craniology should be consulted. 
Fhe situation and direction of the foramen magnum differ greatly in man and 
the lower animals, and to some extent among the different races of man. In 
quadrupeds it is placed dorsally and looks backward, in man at or near the 
centre of the base, and looks downward and slightly forward in the European, 
downward and slightly backward in the negro; while in the anthropoid apes it 
is intermediate in position and direction as compared with that in man and the 
quadrupeds. 
The most frequent irregularity of farm is want of symmetry, which is usually 
pi esent to a slight degree. Asymmetry usually depends upon premature synos- 
osis or closure of one or more sutures, preventing growth in a direction at right 
ang es to the line of that suture, and tending to increase the growth in other 
irections. Artificial pressure applied in early life may also cause irregularity 
o 01 m, as seen in the case of the Flat-headed Indians. THE ARTICULATIONS 
GEORGE WOOLSEY. 
THE articulations, or joints, are the connections existing between contiguous 
parts of the recent human skeleton. Softer substances intervene between the 
ends of the bones, and a fibrous capsule, with or without accessory ligaments, 
binds them together. 
The articular surfaces, or ends of the bones, which are expanded in the case 
of long bones, are coated by a layer of connective tissue, or hyaline, or white 
fibro-cartilage. When hyaline cartilage is present as articular cartilage, its 
free surfaces are very smooth, and thus minimize friction, and it serves to dimin- 
ish jars by its elasticity. It is thickest where the pressure is the greatest. 
The white fibro-cartilage occurs as connecting jibro-cartilage in the discs between 
the vertebrae and in the symphysis pubis; as inter articular jibro-cartilage in the 
plates in the temporo-raandibular and sterno-clavicular joints, and in the menisci 
in the knee-joint; and as marginal jibro-cartilage in the shoulder and hip-joints, 
where it deepens the sockets. The interarticular fibro-cartilages partly or com- 
pletely divide the joint into two halves; they adjust dissimilar bony surfaces* 
increase the motion and security, and act as buffers to break shocks. Connectives, 
tissue exists between contiguous bones of the skull as suture membrane. 
The ligaments, which are the principal_ objects of study in this section, are- 
strong, inextensible, but pliant bands of white fibrous tissue” continuous with the 
periosteum of the bones they unite. They occur in the shape of a more or less; 
perfect capsule, usually reinforced where there is the most strain by external! 
accessory bands or ligaments derived from intermuscular septa, modified tendons, 
or regressed muscles. 
In joints moving on many axes the entire capsule and surrounding muscles 
are nearly uniformly strong; in those moving on one axis the lateral parts of the 
capsule are strengthened and designated as lateral ligaments. In some cases 
ligaments are formed of yellow elastic tissue, as the ligamenta subflava, where 
the parts united are not in contact. 
The deep surface of the capsule is lined by the synovial membrane, which 
extends to, but not over, the articular cartilage. In the shape of folds or fringes 
it frequently projects into the joint-cavity, especially near the margin of the car- 
tilage, where, often padded with fat, it fills up the interstices between the bones. 
This part of the membrane is highly vascular and liable to become villous and 
pedunculated, in which case it may cause pain by being pinched between the 
joint-surfaces. It secretes a thick, glairy fluid called synovia, which lubricates 
the joint. The synovial cavity sometimes communicates with bursae and vaginal 
synovial membranes in the neighborhood of a joint. 
Embryologically, a joint is formed from the tissue between the adjacent parts 
of the skeleton. This embryonic tissue may become the fibrous tissue of the 
suture membrane where the bones are developed in membrane, as in most of 
the bones of the skull; or it may become the thicker fibro-cartilage of the inter- 
vertebral discs, symphysis pubis, etc., where the bones are developed in cartilage. 
A partial synovial membrane may occur in this intervening cartilage. In more 
movable ioints the svnovial sac is more extensive, and the fibro-cartilage is inter- 204 
THE ARTICULATIONS. 
articular, separating two synovial sacs, as in the sterno-clavicnlar joint, etc. 
These plates of fibro-cartilage may be perforated, or form merely a meniscus, 
attached to the inner surface of the capsule, as in the knee, or they may be 
wanting altogether, as in most of the more movable joints. 
In accordance with these various differences, articulations are more or less 
movable. The classification of joints now employed is largely physiological, 
depending upon the degree and kind of motion, as follows : 
Kinds of Joints. 
A. Synarthrosis is the primary form of articulation, and includes those immov- 
able joints (1) in which the contact of the adjacent surfaces is prevented only by 
a thin layer of fibrous tissue, continuous with the periosteum, as in many of 
the bones of the head ; and (2) those where bone and cartilage are directly united, 
as in the case of the first rib and sternum, etc. Nearly all of this class are liable 
to bony union at different periods in advanced life, and in early life permit inter- 
stitial growth. In the skull these articulations are called sutures, of which we 
distinguish three varieties. 
. True sutures include serrated and dentated sutures, where the margins are inter- 
locked, as in the sagittal and lambdoid sutures, respectively. 
False sutures include harmonic sutures, where there is simple apposition, as 
between the two halves of the palate, and squamous sutures, where bevelled edges 
overlap one another, as in the squamo-parietal suture. 
Grooved suture, or schindylesis, is where an edge of one bone fits into a groove 
in another, as in the case of the rostrum of the sphenoid and the vomer. 
Synchondrosis is generally a temporary form of joint, where the thin layer of 
cartilage between the bones usually ossifies before adult life, as in the union 
between the epiphysis and shaft of long bones, and between the sphenoid and 
•occipital bones. 
B. Amphiarthrosis applies to joints which permit of slight movement, and 
include symphysis, where the opposed surfaces are united by a disc or plate of 
white fibro-cartilage, as between the bodies of the vertebrae or the pubic bones; 
and syndesmosis, where an interosseous ligament unites the surfaces, as in the 
lower tibio-fibular articulation. 
C. Diarthrosis applies to the more perfect and movable joints containing 
synovial cavities. Except for the smooth cartilage-clad ends of the bones, these 
are lined by synovial membrane, secreting synovia, which serves for the lubrica- 
tion of the joint. The bones are bound together by fibrous ligaments, forming 
more or less perfect capsules, which, tightened in some positions of the bones, 
relaxed in others, are often chiefly controllers of movement, while the surround- 
ing muscles, aided by atmospheric pressure, hold the bones together. The fol- 
lowing varieties are distinguished : 
Arthrodia, or gliding joints, admit of but a limited amount of gliding motion, in 
one or more directions, between two nearly flat articular surfaces, as in the carpus 
and tarsus, and between the articular processes of the vertebrae. 
Ginglymus, or hinge-joints, allow only movements of flexion and extension on 
one axis, between the cylindrical or trochlear convex and concave surfaces, as in 
the elbow and ankle. 
Condyloid joints present spheroidal articular surfaces, which allow abduction, 
adduction, and circumduction, besides flexion and extension, as in the metacarpo- 
and metatarso-phalangeal articulations. 
Saddle joints allow the same motions as condyloid. The surfaces are recipro- 
cally saddle-shaped ; hence they are sometimes called joints by reciprocal recep- 
tion. The carpo-metacarpal joint of the thumb is an example. 
Ball-and-socket joints (enarthrosis) permit movement in every direction be- 
tween the spherical head and socket, as in the shoulder and hip. They are the 
most movable of joints. THE ARTICULATIONS OF THE TRUNK AND HEAD. 
205 
Trochoides, diarthrosis rotatoria, lateral ginglymus, or pivot joint is a joint 
between a pivot and a ring, as in the radio-ulnar and atlanto-axial articulations, 
which allows only of rotation. 
The various kinds of movement depend on the shape of the articulating sur- 
faces, and are limited by the connecting ligaments and to a less extent by the 
surrounding soft parts. The different kinds of movement are often combined 
and merged into one another in one joint. 
Rotation is the movement of a bone about some longitudinal axis, often its 
own axis, without much change of position. 
Angular movement increases or decreases the angle between two bones. When 
this movement takes place around a transverse axis, it is called flexion and exten- 
sion, according as the angle is increased or diminished. When it takes place 
toward or from the median plane of the body, the middle finger of the hand, or 
the second toe of the foot, it is called adduction and abduction respectively. 
Circumduction is a combination of the four angular movements, so that the 
moving bone describes a cone-like figure, with the apex at the joint, the base at 
its distal end. 
Gliding is the simplest form of movement, and consists of a simple sliding or 
displacement without marked angular or rotatory motion. It is common to all 
diarthrodial joints, and is the only movement between the plane surfaces of 
arthrodial joints. 
Morphologically, many ligaments are formed by the metamorphosis or regres- 
sion of muscles, due to loss of function, or by the migration of muscles, or by the 
degeneration of osseous and cartilaginous tissue. This is shown by a comparative 
study of vertebrate ligaments, muscles, and bones; and atavistic examples are 
occasionally met with in the human subject. 
The ligaments are never strained by muscles tending to pull the bones apart, 
for, on the contrary, the action of the muscles braces the bones firmly together. 
Many long muscles passing over two or more joints co-ordinate their movements, 
and so economize power. Some long muscles act as elastic ligaments, often 
diffusing the movement produced by the short muscles over more than one joint. 
Two or more joints are sometimes combined, and thus acquire strength, security, 
and a variety of motions, as in the wrist and ankle. 
Kinds of Movement. 
THE ARTICULATIONS OF THE TRUNK AND HEAD. 
1. The Articulations of the Vertebral Column. 
There are two sets of articulations between the movable vertebrae—those 
between the bodies and those between the articular processes. These parts are 
connected together by ligaments ; but intermediate ligaments, not connecting parts 
in contact, help to limit the movements of the spine and to complete the spinal 
The articulations between the bodies of the vertebrae (Figs. 226, 230) are 
amphiarthrodied. The following bind them together: 
The intervertebral discs are tough, elastic, but compressible plates, which are 
placed between and firmly unite the vertebral bodies from the axis to the coccyx; 
but in the sacrum and ' coccyx they are ossified on the surface or throughout. 
They are firmly attached to the opposed surfaces of the bodies, these surfaces 
being covered by a thin layer of cartilage, except near their margins. 1 heir 
shape and size are the same as those of the surfaces of the bodies they connect. 
They are thinnest between the second and third cervical (the weakest spot in the 
cervical column), and thickest and largest in the lumbar region. In the cervical 
and lumbar regions they are thicker in front than behind, and thus cause me 206 
THE ARTICULATIONS. 
convexity forward in the former, and increase that in the latter, region. Those 
in the thoracic region are thicker behind, if anywhere, and so increase its curve. 
They form in the aggregate one-quarter of the length of the movable part of 
the vertebral column, which assumes a single curve, concave in front, the curve 
of old age, if the discs are removed or dried up. In structure the discs are made 
up of two parts. The external or laminar portion forms more than half the 
POST. COM- 
MON LIGAMENT 
CARTILAGE 
SUPRASPINOUS 
LIGAMENT 
BODY OF VERTEBRA 
SPINOUS 
PROCESS 
Fig. 226.—Tw0 lumbar vertebrae in sagittal section. (Testut.) 
mass, and consists of concentric layers of fibrous tissue with more and more 
cartilage-cells toward the centre. The fibres pass obliquely between the vertebrae 
and in the reversed direction in adjoining layers. Some layers are found only in 
front, making this part of the disc thicker, so that the central or pulpy portion is 
situated a little behind the centre. The latter is a yellowish elastic, ball-like 
mass, composed of a fine fibrous matrix, imbedded in which is a net-work of 
angular, branching cells, more numerous toward the centre. It is a remnant 
of the notochord. On section of the disc through the pulpy portion the latter 
bulges out above the rest, showing that it is compressed by the laminar portion, 
so that it forms, as it were, a ball or pivot upon which the vertebral bodies move. 
A synovial cavity is described by Luschka in each central pulpy portion. The 
intervertebral discs are surrounded on all sides by a sheath of fibrous ligaments, 
incomplete laterally where the thin and more or less scattered fibres reach from one 
bone to the next, and are sometimes called the lateral or short vertebral ligaments. 
The anterior common ligament is the strong band on the front of the bodies of the 
vertebrae. It extends from the under surface of the occipital bone, in the median 
line in front of the foramen magnum, to the front of the sacrum, reappearing 
below as the anterior sacro-coccygeal ligament. Above it is narrow and cord-like, 
and forms the thickened central portion of the anterior occipito-atlantal and of the 
anterior atlanto-axial ligaments. Below this it becomes broader as it descends. Of 
its fibres, which are dense, well-marked, and longitudinal, the superficial pass over 
several, the deep only between adjacent vertebrae. The fibres are attached to the 
intervertebral discs and to the edges of the vertebral bodies, and bridge over the 
median depressions of their ventral surface, thus rendering this surface more 
even. It limits extension. 
The posterior common ligament extends along the dorsal surface of the bodies 
of the vertebrae within the spinal canal from the basilar groove of the occipital 
bone to the coccyx. Its upper end, often bilaminar, forms the posterior occipito- 
axial ligament between the axis and occipital bone. It is broad and even in the 
neck, extending completely across the vertebral bodies, narrower and dentated 
below. The broad dentations are at its attachment to the discs and margins of 
the vertebrae, and between them are the narrowed portions, separated from the 
backs of the bodies by venous plexuses. The superficial fibres extend over several THE ARTICULATIONS OF THE VERTEBRAL COLUMN. 
207 
vertebrae, the deep over one or two. Its smooth, shining, dorsal surface is sep- 
arated from the dura by loose connective tissue except at the foramen magnum. 
It limits flexion. 
The joints between the articular processes are arthrodial or gliding joints. 
They are provided with synovial cavities, enclosed by capsular ligaments, which 
are loosest in the neck, strongest and tighter in the lumbar region, and tightest in 
the thoracic region. In the neck the inner part of the capsule is formed by the 
elastic tissue of the ligaraenta subflava, which form more and more of the capsule 
in the thoracic and lumbar regions. 
Intermediate Ligaments Uniting the Neural Arches.—The ligamenta subflava, 
composed of yellow fibrous tissue, connect the laminae of adjacent vertebrae from 
the axis to the sacrum. In the upper two spaces they are continued, with less, 
or no, elastic tissue, under special names. Superiorly they are attached to the 
ventral surface of the laminae, above their lower borders, and inferiorly to 
the upper borders and the adjacent parts of the dorsal surfaces. They become 
thicker and stronger below, and are best seen from in front. Laterally they 
are continuous with, and form part of, the 
capsular ligaments, reaching as far as the 
intervertebral foramina; mesially the lateral 
halves unite beneath the roots of the spines, 
from which point the interspinous ligaments ex- 
tend back as membranous bands between the 
adjacent borders of the spines. These are 
best marked in the lumbar region, where the 
fibres extend from the root of one spine to 
the tip of the next above. In the cervical 
region they are replaced by the interspinales 
muscles. They extend dorsally to the supra- 
spinous ligaments, which form a continuous 
cord along the tips of the spines from the 
spine of the seventh cervical vertebra to 
the coccyx, covering the lower end of the 
sacral canal. They consist of longitudinal 
fibres, of which the deep fibres connect the 
tips of adjacent spines, and the superficial 
pass over several. Above it is continued to 
the external occipital protuberance as the 
Ugamentum nuchce (Fig. 227), from which a 
thin median septum passes forward to be at- 
tached to the occipital crest and the cervical 
spines. In the lower animals the nape fo- 
ment is strong and elastic, and supports the 
head • iu man it is of mixed white and yellow fibrous tissue in structure, and 
forms a median intermuscular septum of no great importance. 
The intertransverse ligaments are unimportant and indistinct bands between 
the transverse processes. They are rounded and small in the thoracic region; 
they correspond to the ventral part of the superior costo-transverse ligaments in 
the lumbar region, and are wanting or replaced by the mtertransversales muscles 
in the cervical region. 
Movements— The spinal column must combine strength with mobility, for, as 
the axis of the skeleton, it has to bear great weight and resist shocks. For this 
reason, and to avoid injury to the contained spinal cord it is necessary that the 
movement between any two vertebrae should be slight while that of the column, 
as a whole is very considerable. Motion occurs in all directions around the pulpy 
portion of’the discs as a centre, and is limited in part by the ligaments, m part 
by the articular processes, which thus steady the column. Motion is most free 
where the bodies are smallest or the intervertebral discs thickest. The former 
OCCIPITAL BONE _ 
Fig. 227.—The ligamentum nuchse, seen 
Tom the right side. (Henle.) 208 
THE ARTICULATIONS. 
condition is found in the cervical, the latter in the lumbar region, and these are 
the two most movable parts. The direction of motion in any region is regulated 
by the shape of the articular processes. 
In the neck all movements are permitted by the obliquity of the articular 
processes. Extension is more free than elsewhere, and flexion is free, but less 
than in the lumbar region. Lateral flexion is more extensive than in any other 
region, but it is a combination with rotation, neither motion occurring freely 
by itself, except in the lower cervical region, where rotation is free. But little 
motion is allowed between the axis and the third cervical vertebra, owing to the 
thinness of the disc and the overlapping of the axis in front. 
In the thoracic region extension is checked by the overlapping of the laminae 
and spines, as well as by the shape of the articular processes. The latter also 
prevent flexion. As the articular processes lie in the arc of a circle of which the 
centre is in front between the bodies, rotation is permitted and is most free in the 
upper part. Lateral flexion, otherwise possible, is prevented by the ribs. 
In the lumbar region, owing to the thickness of the discs (especially between 
the lower three vertebrae), flexion is very free, extension moderately so. The 
centre of the circle in which the articular processes lie is situated behind ; but, 
owing to the fact that these processes do not fit closely together, a slight amount 
of rotation and some lateral flexion are permitted, the lateral motion being also 
limited by the great transverse diameter of the bodies. 
Motion is therefore most free in regions whose curve is convex forward, 
whose spinal canal and the contained spinal cord are largest, and where there 
are no bony cavities containing viscera. The ligamenta subflava complete the 
spinal canal, prevent the capsular ligaments from being nipped between the 
articular surfaces during motion, and restore these surfaces to their normal 
position after movement. They have but little, if any, effect in limiting flexion 
or restoring the column to the erect position after flexion. 
2. The Articulations and Ligaments Between the Atlas, Axis, and Occipital 
Bone. 
The essential difference between these and the intervertebral articulations 
in general lies in the absence or modification of the intervertebral discs. The 
specialization of motion between these three bones results in some differences in 
the ligaments, though most of them are the continuation of the series found 
below. 
A. The Articulations between the Axis and the Atlas (Figs. 228, 229).—There 
are here two sets of synovial joints or articulations : 
1. The joints between the superior articular processes of the axis and the 
lateral masses of the atlas are arthrodial. Each is surrounded by a capsular 
ligament, strengthened at the inner and dorsal aspect by an accessory ligament, 
which passes from the back of the body of the axis upward and outward, along 
the outer edge of the occipito-axial ligament, to the lateral mass of the atlas 
behind the transverse ligament. 
2. The articulations of the odontoid process in the ring between the ventral 
arch of the atlas in front and the transverse ligament behind are of the trochoides 
class. There are two synovial sacs—one in front, between the odontoid process 
and the atlas ; the other and more extensive one behind, between the odontoid 
process and the transverse ligament. These two sacs are separated by transverse 
fibres, which pass from the sides of the odontoid process to the atlas, in front of 
the tubercles for the transverse ligament. The transverse ligament is a thick, 
dense, and very strong band, which passes across the ring of the atlas between 
the tubercles on the inner side of its lateral masses. It is arched slightly 
backward, flattened from before backward, and cartilage-clad in front as it passes 
behind the narrowed and faceted neck of the odontoid, which it holds in place, 
and by doing this preserves our lives. From and across the centre of its dorsal THE ARTICULATIONS BETWEEN THE ATLAS, AXIS, ETC. 
209 
aspect thin bundles of fibres pass upward and downward to the cranial aspect of 
the anterior border of the foramen magnum and to the dorsum of the body of 
the axis respectively. These with the transverse portion form a cross, hence the 
name crucial ligament, sometimes applied to the group. Two other ligaments 
unite the axis and atlas. The anterior atlanto-axial ligament is a thin membrane 
between the ventral arch of the atlas and the front of the body of the axis, rep- 
BASILAR PROCESS 
ANTERIOR LIGAMENT- 
ANTERIOR OCCIPITO- 
ATLANTAL LIGAMENT 
POSTERIOR OCCIPITO- 
AXIAL LIGAMENT 
MIDDLE ODONTOID- 
LIGAMENT 
MIDDLE OCCIPITO-AXIAL 
TRANSVERSE 
■ LIGAMENT 
LIGAMENT 
ATLAS' 
.AXIS 
THIRD CERVICAL, 1 
VERTEBRA 
POSTERIOR 
■■“ LIGAMENT 
Fig. 22S.—Sagittal section of the joints between the occipital bone and the atlas and axis. (Testut.) 
resenting the anterior common ligament, whose direct upward continuation is 
seen as "a median cord-like thickening of the ligament attached to the ventral 
tubprclp of the atlas. The 'posterior atlanto-axial ligament represents the liga- 
menta snbflava, but has little elastic tissue. It loosely connects the dorsal arch 
of the atlas and the laminae of the axis, and is perforated on each side by the 
second cervical nerves. oons 
B Ligaments between the Axis and the Occipital Bone (Figs. 228, 229). 
The occinito-axkdor oeeipito-cervieal ligamentis the upper end of the posterior 
common ligament extending from the third and second cervical vertebral to 
the basilar groove of the occipital bone. Some of its fibres pass over the axis 
without attachment, giving rise to two layers of which the hind one may be 
designated the posterior, and the forward one th 
The lateral odontoid,alar, or check ligament are two strong fibrous cords, w 1 eh 
extend from the sides of the summit of the odontoid process transversely out- 
ward to the rough impression on the inner side of each occipital condyle. They 
lie „t „ u+t]e higher level than the transverse ligament. Each is made tense by 
i , , .i ounosite side. The middle odontoid or suspensory hga- 
turning he is a slender, median, fibrous tend connect- 
ing (anterior P -d™oid and the fore part ’of the margin of the foramen 
m^nnmaPeit is tightened by extension. 
14 210 
THE ABTICULA TIONS. 
The suspensory ligament is derived from the sheath of the notochord, between 
the first vertebral centrum and the basi-occipital, and is homologous with an inter- 
vertebral disc. The transverse and check ligaments are each derived from the 
conjugal ligaments (ligamentum conjugale costarum). These, in the embryo, con- 
nect the heads of each pair of ribs or costal processes around the back of the inter- 
vertebral discs, and persist as the interarticular ligaments of the heads of the ribs. 
Fig. 229.—Articulations of the occipital bone with the upper cervical vertebrae. The arches have been 
removed, and the spinal canal is thus exposed. (Testut.) 
Movements.—ln the atlanto-axial articulation rotation of the head together with 
the atlas takes place around the odontoid process as a pivot for about 30° to either 
side in a nearly horizontal plane. It is limited by the check and atlanto-axoidean 
ligaments. As both facets in each lateral atlanto-axoidean articulation are con- 
vex, with the convexities in contact when the head looks forward, rotation causes 
the convexities of the atlantal facets to descend from those of the axis. This 
decreases the space and relaxes the ligaments between the bones, thus allowing 
further rotation, with security in all positions. Slight flexion and extension and 
some lateral flexion are also allowed between the atlas and the axis. 
C. The Articulations of the Atlas with the Occipital Bone.—This consists of 
a symmetrical pair of condylar joints between the occipital condyles and the 
upper facets of the lateral masses of the atlas. Each joint is provided with a 
rather lax capsular ligament. In front and behind these the ventral and dorsal 
arches of the atlas are connected with the margins of the foramen magnum by 
the anterior and posterior occipito-atlantal ligaments respectively. The anterior 
occipito-atlantal ligament is thin and membranous, strengthened in front in the 
median line by a round accessory ligament, which is the upper end of the anterior 
common ligament. The posterior occipito-atlantal ligament represents the liga- 
mentum subflavum, but is without elastic fibres, and is also thin and membranous. THE ARTICULATIONS OF THE THORAX. 
211 
This ligament does not limit motion between the bones. The dura is adherent 
to its ventral surface, and the dorsal surface lies in the floor of the suboccipital 
triangle. A band of fibres at the lateral margins of the ligament arches over the 
back of the vertebral groove on each side to the superior articular process, com- 
pleting a foramen for the vertebral artery and the suboccipital nerve. The lateral 
occipito-atlantal ligaments are strong fibrous bands between the transverse processes 
of the atlas and the jugular processes of the occipital on each side, which 
strengthen the capsular ligaments externally, and lie behind the rectus capitis 
lateralis muscles. 
Movements of flexion and extension are freely allowed. Extension is checked 
by the anterior occipito-atlantal, flexion by the occipito-axial and hind part of the 
capsular ligaments. Some lateral gliding is also allowed, by which the outer 
edge of the condyle on the one side is depressed, and on the other is elevated in 
relation to its socket. Or the movement may be obliquely lateral, one condyle 
advancing slightly at the same time that it is depressed toward the median line, 
while the opposite condyle takes the reverse position. This is the position of 
greatest stability, and is assumed in the most easy and natural attitudes. Lateral 
movements are restrained by the check ligaments and the lateral parts of the cap- 
sules. No true rotation is allowed. 
The symmetrical and bilateral arrangement of these joints, combined with 
the median odontoid pivot, provides the strength and security which are necessary 
to life, and which are greater than are obtained in a ball-and-socket joint, with 
equal freedom of motion. A passageway for the cord is also provided, subject 
to less motion than in case the joint were of the ball-and-socket variety. 
The ligaments passing over and between the odontoid process and the occiput 
by being lax in the erect position allow of flexion, which tightens them. The 
head balances upon the fore part of the condyles when the orbits look a little 
upward. By this arrangement, characteristic of the human figure, the head is 
held erect without undue muscular effort or a strong ligamentum nuchas. If the 
muscles relax, the head will nod either forward or backward according as the 
centre of gravity is in front or behind the balance line. 
3. The Articulations of the Thorax. (Figs. 230, 231.) 
A. The Costo-vertebral Articulations, or those between the ribs and the ver- 
tebrae, are subdivided into eosto-central and costo-transverse articulations. 
(a) In the eosto-central articulation the head of the rib is united to the body 
of a single vertebra in the case of the first, tenth, eleventh, and twelfth ribs, 
elsewhere to the bodies of two vertebrae and the intervening intervertebral 
disc. When the rib-head articulates with a single vertebra, there is a single 
synovial sac, otherwise two separate sacs, surrounded by a capsular ligament, 
which is composed of short fibres and is reinforced in front by the anterior 
eosto-central or stellate ligament. This consists of pearly-white fibres, radiating 
from the front of the head of the rib upward to the body of the vertebra above, 
forward to the intervertebral disc, and downward to the body of its proper ver- 
tebra. In the case of the first, tenth, eleventh, and twelfth ribs the stellate 
arrangement of fibres is not quite as distinct. The inter articular ligament is a 
thin, transverse band of short, strong fibres between the intervertebral discs and 
the ridge separating the two facets on the head of the rib, excepting the first, 
tenth, eleventh, and twefth, where it is wanting. It separates the two synovial 
sacs, and is loose enough to allow of moderate rotation. 
(b) The costo-transverse articulation is between the tubercle of each rib of the 
upper ten pairs and the front of the tip of the transverse process of the vertebra 
bearing the same number as the rib. Each joint has a thin, loose capsular lig- 
ament, enclosing a synovial sac, and strengthened on three sides by the costo- 
transverse ligaments. The middle costo-transverse or interosseous ligament consists 
of short horizontal fibres between the back of the neck of the rib and the front 212 
THE ARTICULATIONS. 
of the corresponding transverse process, and extending from the capsule of the 
costo-central to that of the costo-transverse articulation. It is best seen in a 
transverse section, and is rudimentary in the case of the eleventh and twelfth 
ribs. The 'posterior costo-transverse ligament is a short strong band extending 
from the outer end of the transverse process outward and upward to the rough 
non-articular part of the tubercle of the corresponding rib. It is wanting to the 
eleventh and twelfth ribs. The superior costo-transverse ligament consists of a 
broad, flat, fibrous band between the upper border of the neck of each rib below 
the first, and the lower border of the transverse process next above it. Two layers 
are often distinguishable—the ventral, passing upward and outward, the dorsal 
and more scattered fibres passing upward and inward. Externally this ligament 
is continuous with the fascia lining the external intercostals; internally it is free 
and thickened; in front it is in relation with the intercostal vessels and nerves. 
TRANSVERSE process 
ANTERIOR COM- 
MON LIGAMENT 
SUPERIOR 
TRANSVERSE LI GA MENT M 
V ANTERIOR COSTO- 
ST'CENTRAL LIGAMENT 
MIDDLE COSTO-TRANS 
VERSE LIGAMENT 
» i 
POSTERIOR COSTO- 
TRANSVERSE LIGAMENT 
Fig. 231.—Costovertebral articulations in horizon- 
tal section : upper surface of lower segment, right 
side. (Testut.) 
Fig. 230—Articulation of the vertebral bodies with 
each other, and of the ribs with the spine. (Testut.) 
B. The Costo-chondral Synarthroses.—The costal cartilages are joined to the 
cup-shaped ends of the ribs by the continuity of the investing perichondrium and 
periosteum. 
C. The Chondro-sternal Articulations are between the fossse on the lateral 
borders of the sternum and the inner ends of the cartilages ot the upper seven 
(the sternal) ribs. The first rib is joined by synarthrosis to the sternum. The 
others have synovial joints, generally single, but in the case of the second rib 
usually double on one or both sides. When the synovial sac is double, an inter- 
articular ligament connects the ridge on the facet of the cartilage with the fibro- 
cartilage between the manubrium and body of the sternum. A similar ligament 
sometimes exists in the other joints. The synovial sac is frequently obliterated 
in the joints of the sixth and seventh cartilages. The chondro-sternal joints are 
surrounded by short capsular ligaments, most developed in front, above, and below, 
where they are called, respectively, anterior, superior, and inferior chondro-sternal 
ligaments. In the anterior ligament the fibres radiate from the front of the inner 
end of the cartilage to the front of the sternum, where they decussate with the oppo- 
site ligament and adjoin those above and below. The so-called posterior chondro- 
sternal ligament is little more than the continuity of periosteum and perichondrium STERNAL AItTICULA TIONS. 
213 
with a few accessory capsular fibres. The chondro-xiphoid ligament is a flat band 
connecting the front of the xiphoid cartilage with that of the seventh, and often 
of the sixth, costal cartilage. 
D, The Interchondral Articulations are arthrodial joints between the cartilages 
from the sixth to the ninth (inclusive), situated a little in front of their upward 
bend, where blunt processes on the lower edges come in contact with the upper 
margins of the cartilages below. They have a complete capsule enclosing a 
synovial sac, and reinforced by oblique fibres from the anterior intercostal fascia. 
E. Sternal Articulations.—The union of the manubrium and body of the 
sternum forms a symphysis in which the connecting fibro-cartilage may contain 
a partial synovial cavity with a layer of cartilage above and below. The fibres 
of the radiating chondro-sternal ligaments and the periosteum, reinforced by 
longitudinal fibres in front and behind, but especially behind, strengthen the 
union of these two parts. The xiphoid cartilage is similarly united synar- 
throdially to the lower end of the body of the sternum, at a level somewhat behind 
that of the ventral surface of the sternum. The chondro-xiphoid ligament is an 
accessory ligament of this joint. The connecting cartilage may ossify in old age. 
Movements of the Ribs and of the Thorax as a Whole (Fig. 232).—In inspira- 
tion the thorax is enlarged in its three diameters, transverse, antero-posterior, and 
vertical. The increase in the vertical 
diameter is caused partly by the eleva- 
tion of the upper ribs, and the result- 
ing widening of the intercostal spaces, 
but is mainly due to the action of the 
diaphragm. The increase in the other 
two directions is due to the move- 
ments of the ribs, which are greatest 
where the ribs are longest, most ob- 
lique, and most curved at their angles 
(i. e., at the sixth, seventh, and eighth 
ribs opposite the bulkiest part of the 
lungs), and least in the short flat first 
and second ribs. 
As the ribs articulate with the 
vertebrae by two series of closely ap- 
proximated joints, the axis of rotation, 
which is the chief movement here, 
must pass through both joints—i. e., 
obliquely outward, backward, and 
somewhat downward. When the up- 
ward rotation of inspiration occurs, the 
ventral ends of the ribs, which are 
inclined obliquely downward, are elevated. By thus decreasing the obliquity of 
the ribs the front wall of the thorax is carried upward and forward, and its cavity 
is enlarged sagittally. The ventral ends of the ribs cannot be elevated without 
straightening out the angles with the costal cartilage, which throws this end of the 
ribs outward, transverse diameter in front. The return of the cos- 
tal cartilages to the natural angle after inspiration is a principal factor in the 
resiliency of the thorax, to which quiet expiration is due. As the axis of rotation 
is oblique, upward rotation also elevates the lateral part of the ribs and everts 
their lower borders, thus increasing the transverse diameter behind. In the 
first ribs the axis is more nearly transverse; hence their motion is mostly a 
slight elevation and depression of their fore parts. But as the obliquity of the 
axis increases from above downward, the outward movement becomes more exten- 
sive in the lower ribs. Owing to the plane and sloping articular surfaces on the 
transverse processes of the vertebrae, from the seventh to the tenth only, there 
is besides rotation, a slight backward and upward motion in inspiration and 
Fig. 232.—Diagram of the displacement of the ribs 
and sternum in inspiration; a indicates the degree of 
upward movement; b, that of forward movement. (Tes- 
tut.) 214 
THE ARTICULA TIONS. 
the opposite in expiration, which is still more marked in the eleventh and twelfth 
ribs, where there are no costo-transverse articulations. In the upper six ribs, 
where the facets on the transverse processes are situated lower and are more con- 
cave as we ascend, there is rotation only. In the case of the eleventh and twelfth 
ribs there is little elevation, and the twelfth rib may even be drawn downward in 
inspiration by the quadratus lumborum. The widening of the lower part of the 
thorax in inspiration increases the power of the diaphragm and counteracts the 
compression of the abdominal viscera. The costo-vertebral articulations with 
their ceaseless movement are remarkable for their freedom from disease. 
At the chondro-sternal articulations, except the first, there is a slight hinge- 
motion on two axes, sagittal and obliquely vertical. Owing to these two move- 
ments the sternum is carried neither so far forward nor upward as the anterior 
ends of the ribs and cartilages. Otherwise its motion would be detrimental to 
the heart, etc. behind. In the interchondral joints only a limited gliding is 
allowed, and the sternal articulations merely increase the elasticity and strength 
of the sternum. 
The hinge-motion, often wrongly ascribed to the ribs at the costo-central 
joints, can only occur with a sliding motion at the costo-transverse articu- 
lation. Although this may occur in the lower ribs, it cannot in the upper, owing 
to the rounded concavities in the transverse processes. Slight rotation on a single 
axis, as above indicated, accounts for all the motions ascribed to the ribs. 
4. The Temporo-mandibular Articulation (Figs. 233-235). 
This articulation consists of a pair of symmetrically placed ginglymo-arthro- 
dial joints. Their dissimilar articular surfaces, the ventral halves of the glenoid 
fossae, and the articular eminences of the squamous portions of the temporal bones 
MASTOID 
PROCESS' 
PTERYGOIDEUS 
—EXTERNUS 
Fig. 233.—Temporo-mandibular articulation in sagittal section. (Testut.) 
above and the condyles of the mandible below, are adjusted together by the inter- 
posed interarticular cartilages. It is best seen when the jaw is divided in front of 
the ramus, and the latter is freed of its attachments. 
The bones are united by a thin loose capsular ligament attached outside of the 
articular surfaces on the two bones. The external lateral ligament consists of 
those accessory fibres, strengthening the capsule, which pass from the lower border 
and tubercle of the zygoma downward and backward to the outer side and back of 
the neck of the condyle. This ligament on one side serves as the internal liga- 
ment of the opposite side. The inner part of the capsule, sometimes called the 
short internal lateral ligament, does not deserve the name. 
The interarticular cartilage is a thin, oval plate of fibro-cartilage, concavo- 
convex from before backward on its upper aspect to fit the temporal surface, and 
concave below to receive the condyle of the lower jaw. It is thickest behind, 
and thinnest at the centre, where it is sometimes perforated. By the close attach- 
ment of its circumference to the capsule the joint is divided into two synovial 
cavities, of which the upper is the larger and looser, and the lower extends lower THE TEMPORO-MANDIBULAR ARTICULATION. 
215 
clown behind than in front. The two sacs communicate when the cartilage is 
perforated. Some fibres of the external pterygoid muscle are inserted into the 
cartilage in front. 
The accessory ligaments are—(1) the spheno-mandibular or long internal lateral 
ligament, a thin band some little distance from the joint, extending from the 
Fig. 234.—Temporo-mandibular articulation, external view. (Testut.) 
spine of the sphenoid downward and a little forward to the lingula of the man- 
dible. Separating it from the joint and the ramus are the external pterygoid 
muscle, the internal maxillary vessels, the inferior dental nerve and vessels, the 
auriculo-temporal nerve, and the middle meningeal artery. It represents the 
fibrous remains of a part of Meckel's cartilage. (2) The stylo-mandibular liga- 
ment is a specialized band of the deep cervical fascia extending from near the tip 
of the styloid process to the angle and the hind border of the ramus of the jaw, 
between the masseter and internal pterygoid 
muscles. It separates the suomaxillary liom 
the parotid gland. 
The movements in this joint are -(I) the 
hinge-motions of elevation and depression, and 
(2) the gliding motions of protrusion and i c- 
traction, both (a) simple and (b) oblique or 
grinding. The movements in the two synovial 
compartments are of different kinds. In the 
upper there is a protrusion and a retraction, or 
a forward and backward gliding, of the carti- 
lage together with the condyle on the temporal 
bone, due to the closer connection ot the carti- 
lage with the condyle than with the temporal 
bone, and to the insertion of the external ptci y- 
goid or protrusor muscle into both caiti age 
and condyle. In the lower part there is a 
hinge-motion, on a transverse axis, be ween 
the condyle and the cartilage. +-00,-0 nmn 
In opening the month the (1) hinge and (&) s.mpk ghdmg motions a e com- 
bined, When the mouth is opened hut slightly (as m talking) there is simply a 
Fig. 235.—Temporo-mandibular articula- 
tion, mesial view. (Testut.) 216 
THE ARTICULATIONS. 
hinge-motion in the lower compartment. When, however, the mouth is opened 
more and more widely, besides an increased hinge-motion, the cartilage and con- 
dyle glide forward onto the articular eminence. The condyle does not normally 
reach the summit of the eminence, but when, as in a convulsive yawn, it glides 
over the summit, it slips into the zygomatic fossa, and there is a dislocation with 
rupture of the back of the capsule. As the cartilage and condyle glide forward 
the external lateral ligament remains always tense on account (1) of the down- 
ward movement onto the eminence, and (2) of the increased hinge-motion which 
the ligament allows when its obliquity is straightened by the forward movement 
of the condyle. The point of least motion, or the axis of motion, in the com- 
bined movement is approximately at the inferior dental foramen, and thus stretch- 
ing of the nerve is avoided. The combination of hinge and gliding motion gives 
a tearing as well as a cutting action to the incisors. 
(2a) There may be a simple protrusion and retraction of the lower jaw by a 
gliding motion in the upper compartment. A slight lowering of the rami occurs 
as the cartilages and condyles pass downward and forward onto the eminences. 
(26) An obliquely horizontal or rotary grinding motion is caused by the alternate 
gliding forward and inward on one side, and backward and inward on the other. 
The nerves supplying the joint are branches of the masseteric and auriculo- 
temporal. 
THE ARTICULATIONS OF THE UPPER EXTREMITY. 
1. The Sterno-clavicular Articulation. (Fig. 236.) 
The arthrodial joint between the inner end of the clavicle and the superior 
angle of the manubrium sterni, together with the cartilage of the first rib, is the 
only point of attachment of the skeleton of the shoulder-girdle and upper limb 
to that of the trunk. The dissimilar articular surfaces are harmonized by the 
intervening fibro-cartilage, and are connected together by a fairly tight capsular 
ligament, whose fibres pass obliquely upward and outward from the circumference 
of the sternal to that of the clavicular facet. This capsule is strongest behind 
and in front, where it is called respectively the posterior and anterior sterno-clavic- 
ular ligaments. Above it is supplemented and strengthened by the dense inter- 
FIBRO-CARTILfIGE 
Fig. 236.—Sterno-costo-clavicular articulation, front view. The right half is seen in coronal section. (Testut.) 
clavicular ligament which passes between the upper and back parts of the sternal 
ends of the two clavicles and their capsular ligaments, and dips down in the 
middle to be attached to the hind border of the interclavicular notch of the ster- 
num. Below, where the capsule is thinnest, is the strong, dense, accessory band, THE SC A. PULO- CL A VICULA B AB TICE LA TION. 
217 
the costo-davieular or rhomboid ligament. This is directed obliquely upward, 
outward, and backward from the front and upper aspect of the first costal 
cartilage to the rhomboid impression on the under surface of the inner end of the 
clavicle. 
The inter articular fibro-cartilage is a flattened disc of about the same shape 
and size as the inner articular surface of the clavicle. It is thinnest at the centre 
and below, thickest above. It is attached above to the upper and dorsal border 
of the articular surface of the clavicle and below to the inner end of the cartilage 
of the first rib. By the attachment of its circumference to the inner surface of 
the capsule the joint is divided into two synovial cavities, of which the outer is 
the looser, and is continued a short distance beneath the clavicle on the first costal 
cartilage. The two occasionally communicate through a perforation in the centre 
of the fibro-cartilage. 
The fibro-cartilages and interclavicular ligament together represent the epi- 
sternal bone of lizards. 
Movements.—The clavicle carrying the scapula, to which the coraco-clavicular 
ligaments closely bind it, may move on its inner end as a centre in an upward 
and downward direction on a sagittal axis ; in a forward and backward direction 
on a vertical axis; or, by a combination of these, a circuraductory motion may 
be obtained, in which the clavicle describes a cone of which the base is at its outer 
end. A slight rotation of the clavicle on its long axis is also permitted by which 
its ventral surface is turned upward as the arm is raised, and vice versa. 
The fibro-cartilage serves as an elastic buffer to break shocks and resist pressure 
from the shoulder, as well as to connect the bones and prevent inward displace- 
ment. The interclavicular and rhomboid ligaments are safeguards against 
upward displacement of the inner end of the clavicle in depression and elevation 
of the arm, and the rhomboid ligament also resists backward displacement. 
When one clavicle is much depressed the interclavicular ligament draws the 
other one up—a fact to be remembered in fracture of the bone. In forced 
depression of the clavicle it presses on the first rib, which acts as a fulcrum, so 
that the inner end is raised and its ligaments are put on the stretch. 
2. The Scapulo-clavicular Articulation. 
The acromio-clavicular joint is an arthrodial articulation between the bevelled 
outer end of the clavicle and the inner margin of the acromion process, in 
which the bones are held together by a somewhat lax capsule, which allows 
some play between the surfaces. The capsule, whose fibres pass from the acro- 
mion inward and backward, is especially stiong abo'se, forming the superieyi 
acromio-cla;vicular ligament, and is here also strengthened by the fascia of the 
trapezius and deltoid. The inferior part, m/mor ligament, is weak, as is also the 
posterior. The synovial cavity is sometimes < partially, rarely completely, divided 
into two" by a small wedge-shaped inter articular fibro-cartilage, attached by its 
base to the superior ligament, and usually occupying the upper part of the joint 
only. . 
The coraco-clavicular ligament, which binds the clavicle to the coracoid process 
of the scapula is the strongest connection between the clavicle and scapula, and 
consists of two parts • (1) The conoid ligament, the dorsal and internal fasciculus, 
is a strong triangular band attached by its apex to the inner and hind part of the 
root of the coracoid process, from which its fibres spread upward, backward, 
and outward to and about the conoid tubercle of the clavicle. (2) The trapezoid 
ligament is the flat, quadrilateral, outer and fore part, whose fibres slope upward, 
backward, and outward from the upper surface of the dorsal half of the coracoid 
process to the trapezoid ridge on the under surface of the clavicle. A small 
bursa often exists between these two igaments. . , 
Movements in the aoromio-clavuyutar jomt may take place on, avertical mm by 
which the glenoid cavity is turned farther backward or forward, thus enabling it 218 
THE ARTICULATIONS. 
to keep its relative position in forward or backward movement, respectively, of 
the shoulder-girdle. Or movement may take place on a horizontal axis, by which 
the glenoid cavity is turned farther upward or downward, as when the arm is 
raised or lowered. This motion, combined with elevation and depression of the 
clavicle, is spoken of as rotation of the scapula, on a dorso-ventral axis passing 
through its centre or its upper angle. The movements at the acromio-clavicular 
joint, modifying the relation of the scapula to the clavicle, rarely take place by 
themselves, but only in connection with the movements of the sterno-clavicular 
joint. In the combined movements of the clavicle and scapula the movements of 
the scapula are restricted by the shape of the chest-wall on which it lies, so that 
its principal movements are upward and forward, and downward and backward. 
In the above movements the vertebral border and the lower angle of the scapula 
are generally kept in contact with the thorax by the muscles attached—a condition 
allowed only by the acromio-clavicular joint. The conoid ligament suspends the 
scapula from the clavicle; the trapezoid is tightened when the shoulder is pressed 
inward. 
The Ligaments of the Scapula (Fig. 237).—The coraco-acromial ligament is a 
flat, triangular band attached by its broad base to the outer border of the coracoid 
process and by its blunt apex to the tip of the 
acromion. Binding together the acromion and 
coracoid processes, it forms an arch over the 
shoulder-joint which holds off the deltoid, and 
supports and protects the joint. Its ventral 
and dorsal margins are thick aad strong, 
leaving a thin membranous part between, 
with often a gap near the coracoid process. 
The deltoid covers its upper surface, which 
also looks a little forward ; its lower surface is 
separated by a bursa from the capsule of the 
shoulder-joint. From its outer edge, which 
projects over the centre of the head of the 
humerus, a thin, tough fascia is continued 
under the deltoid and over the subacromial 
bursa and the shoulder-joint. The transverse, 
coraco-scapular or suprascapular ligament, con- 
tinuing the upper border of the scapula, 
bridges across the suprascapular notch, converting it into a foramen, through 
which the suprascapular nerve passes, while the corresponding artery commonly 
passes above it. It is thin and flat, and is sometimes replaced by bone. The 
spino-glenoid ligament comprises a few lax fibres which, by passing between the 
outer border of the spine and the margin of the glenoid cavity, bridge over the 
suprascapular vessels and nerves in passing between the supra- and infraspinous 
fossse. 
CONOID LIGAMENT 
I_TRAPEZOID 
1 LIGAMENT 
!/ CORACOID 
PROCESS 
Fig. 237.—Glenoid fossa of right side. 
(Testut.) 
This ball-and-socket joint, between the large humeral head and the smaller, 
shallow glenoid cavity of the scapula, is one of the most perfect and most movable 
of joints. The surrounding muscles give strength and security to the joint, and, 
together with atmospheric pressure, hold the bones in position much more than 
do the ligaments. The glenoid fossa is deepened by the glenoid ligament, tri- 
angular on section with the base attached around the margin of the fossa. It is 
composed of fibro-cartilage with scattered cartilage-cells. To its upper end is 
attached the long tendon of the biceps, which, dividing, is continued into both 
sides. Outside of this ligament the capsular ligament is attached to the scapula 
around the glenoid margin, sometimes reaching as far as half an inch from it in 
front. From this attachment it passes to the anatomical neck of the humerus. 
At the lower and inner part of the latter it is attached some distance from the 
3. The Shoulder-joint. (Figs. 238-240.) THE SHOULDER-JOINT. 
219 
articular surface, and in front, between the tuberosities, it covers over and is 
attached to the transverse ligament, thus giving passage to the long tendon of the 
biceps. The capsule is composed of longitudinal fibres, with some oblique and 
circular fibres interwoven, and is strongest on its superior aspect. It is so lax 
SUPERIOR GLENO- 
HUMERAL LIGAMENT 
Fig. 238.—Shoulder-joint, rear view. The hind part of the capsular ligament and most of the head of th< 
humerus have been removed. (Testut.) 
that alone it does not keep the bones in contact. Above and behind the tendons 
of the supraspinatus, infraspinatus, and teres minor, in front that of the sub- 
scapularis and below the long head of the triceps aie intimately connected with 
and strengthen the capsule. Between the subscapularis and triceps tendons is an 
Fig. 239.—Shoulder-joint, front view. (Testut.) 
unprotected and weak part of the capsule, usually torn by the passage of the head 
in dislocations, to which the shoulder is very liable, owing in part to the looseness 
of its capsule. Besides the overlying tendons the capsule has two sets of acces- 
sory folds. 
*(1) The eoraco-humeral ligament extends as a strong, broad band from the 
outer border and root of the coracoid process, beneath the coraco-acromial liga- 
ment obliquely over the joint to the anatomical neck of the humerus above the 
areat tuberosity, being intimately connected with the capsule. Seen from in front, 
ft appears as a fan-shaped process lying over and above the capsule, with which it 220 
THE A RTIGULA TIONS. 
appears continuous as viewed from behind. This ligament represents a detached 
part of the pectoralis minor tendon. (2) The gleno-humeral bands, three in num- 
ber, extend between the ventral margin of the glenoid fossa and the neck of the 
humerus. They are seen projecting on the interior of the inner and fore part of 
the capsule when the joint is opened from behind. The superior gleno-humeral 
hand extends between the upper end of the ventral margin of the glenoid cavity 
and the upper end of the small tuberosity of the humerus, forming a slight 
groove, directed backward, for the inner edge of the biceps tendon. It may 
occasionally be quite free from the capsule, and it lies above the opening by which 
the bursa beneath the scubscapularis tendon communicates with the synovial 
Fig. 240.—Shoulder-joint in coronal section, front view. The synovial sac is distended. (Testut.) 
cavity of the joint. The middle gleno-humeral band lies below this opening, 
along the lower border of the subscapularis, arises from the glenoid margin with 
the superior band, and is attached to the inner side of the small tuberosity of 
the humerus. The inferior gleno-humeral band is the strongest, and passes 
between the middle part of the ventral border of the glenoid rim and the lower 
part of the neck of the humerus. The superior gleno-humeral band represents 
the divorced tendon of the subclavius muscle as seen in birds, and corresponds to 
the ligamentum teres in the hip. 
The transverse ligament, by its fibres passing transversely between the tuber- 
osities, forms a canal of that part of the bicipital groove which belongs to the 
epiphysis. The capsular ligament is attached to it superficially. 
The synovial membrane lines both free surfaces of the glenoid ligament, and 
is thence reflected over the inner surface of the capsule to the humeral neck, 
where in front it passes down the bicipital canal for a distance, and there is 
reflected onto the biceps tendon, which it sheathes, as it passes through the joint, 
as far its attachment to the glenoid ligament. Between the superior and middle 
gleno-humeral bands there is usually an opening where the synovial membrane 
is continuous with that lining the bursa beneath the subscapularis tendon. It 
occasionally communicates with a bursa beneath the infraspinatus muscle. 
The articular cartilage is thicker near the centre of the head on the humerus 
and at the margins of the glenoid fossa, thus deepening it. 
Nerves from the suprascapular, circumflex, and subscapular supply the joint. 
Movements.—Flexion and extension, abduction and adduction, circumduction 
and rotation are allowed to a degree determined by the extent of the humeral 
articular surface, the length of the capsule, and the resistance of the overlying 
parts. Flexion and extension, or the movements forward and slightly inward, 
and backward and slightly outward, take place on an axis corresponding to that 
of the head and neck of the humerus, which is nearly perpendicular to the centre 
of the glenoid cavity. Flexion is much more free than extension, and between THE ELBOW-JOINT. 
221 
the extremes of both there is about 90° of motion. In abduction and adduction 
the arm moves away from or toward the body, respectively, on a horizontal axis 
at right angles with that last named, and parallel to the surface of the glenoid 
fossa. Rotation occurs in an outward (or backward) and in an inward (or for- 
ward) direction on an axis drawn from the centre of the head to the inner con- 
dyle of the humerus, and over a range of between 90° and 100°. In extreme 
abduction ( i. e., to about 90°) or extension the great tuberosity strikes against the 
coraco-acromial ligament and the acromion process, arid further motion is thus 
limited. In extreme abduction the lower part of the capsule is tense. In out- 
ward rotation the coraco-humeral ligament is made tense, and in both inward 
and outward rotation the upper part of the capsule is tightened by twisting. 
Otherwise, the muscles rather than the ligaments restrain the movements. The 
great freedom of motion at the shoulder, by which the arm can be raised so as to 
be nearly vertical, is in part due to the movement of the scapula, which always 
accompanies movements at the shoulder-joint. Both abduction and flexion over 
90° are due to rotation of the scapula, by which the glenoid cavity is turned out- 
ward and upward, or forward and upward. In dislocation the coraco-humeral 
ligament is thought to be important in determining the position of the dislocated 
limb and the manipulation for its reduction. 
The subacromial bursa lies between the joint-capsule, with its attached ten- 
dons, and the arch formed by the coracoid and acromion processes and the coraco- 
acromial ligament, and it also extends beneath the deltoid muscle. It facilitates 
the movements of the upper end of the humerus. The coraco-acromial arch 
forms a sort of secondary socket, against which the head and tuberosities of the 
humerus are pressed when the weight of the body is supported by the arms. 
The biceps tendon acts as a ligament of the joint, preventing the humerus 
from being pulled up forcibly against the acromion, and keeping the head in the 
glenoid socket, especially when the arm is away from the side of the body and 
is pulled down by the pectoralis major and latissimus dorsi muscles. 
4. The Elbow-joint (Figs. 241-243). 
This is a true hinge-joint between the trochlear surface of the humerus and 
the great sigmoid cavity of the ulna. It is broadened, and thereby secured against 
INTERNAL 
CONDYLE 
INTEROSSEOUS, 
LIGAMENT 
lateral motion or displacement, by the articulation of the upper end of the radius 
with the capitellum of the humerus. To the shape of the bones is due the 
strength and security of the joint. Beneath the surrounding muscles and ten- 
Fig. 241.—Elbow-joint, mesial view. (Poirier.) 222 
THE ARTICULATIONS. 
dons, which further strengthen the joint, lies the fibrous capsule, reinforced inter- 
nally and externally, and therefore described in four parts. 
The triangular internal lateral ligament is attached by its apex to the lower 
aspect of the internal condyle, and by its base to the inner margin of the coronoid 
and olecranon processes. It is divided into two smaller triangles, ventral and 
dorsal, by an intermediate thinner part attached to the meeting-point of these two 
processes. This ligament is the strongest part of the capsule. 
The external lateral ligament, shorter and narrower than the internal, radiates 
from its upper attachment on the lower part of the external condyle to the 
outer side of the orbicular ligament. A few fibres reach the neck of the radius. 
The anterior ligament is the thin, fore part of the capsule between the lateral 
ligaments. Superiorly it is attached above the coronoid and radial depressions, 
and includes them within the joint; inferiorly it is attached, just beyond the 
articular margin, to the front of the 
coronoid process and to the orbicular 
ligament, some fibres passing to the 
neck of the radius. It is reinforced 
by the adhesion of some of the fibres 
of the brachialis, which draws it up 
in flexion and prevents it from being 
nipped between the bony margins. 
The posterior ligament is thin and 
weak, like the anterior. By its at- 
tachment above and at the sides of 
the olecranon fossa it includes the 
latter within the joint. Its upper 
fibres pass transversely across the 
fossa. Inferiorly it is attached to 
the olecranon process, near the upper 
and outer margins of the great sig- 
moid cavity, to the orbicular liga- 
ment, and to the ulna behind the 
small sigmoid cavity. It is strengthened by the adhesion of the triceps, which 
draws it up during extension. 
The synovial membrane lines the inner surface of the capsule, and thence 
passes onto the humerus, where it lines the olecranon, coronoid, and radial fossae, 
and extends to the articular cartilage. Projecting into the above fossae are 
masses of fat placed between the capsule and the synovial membrane. Inferiorly 
the membrane extends into the superior radio-ulnar joint, where it lines the 
orbicular ligament, thence passing onto and around the neck of the radius, and 
so up to its articular cartilage. A fold of synovial membrane, projecting into 
the joint from in front opposite the outer lip of the trochlea, suggests the division 
of the joint into two parts. 
The nerve-supply is mainly from the musculo-cutaneous, with a few filaments 
from the musculo-spiral, median, and ulna. 
Movements are confined to flexion and extension on an axis obliquely placed 
at an angle of about 84° with the shaft of the humerus, so that in extension the 
forearm is inclined outward and in flexion inward. Flexion occurs through 140°, 
and is limited by the contact of the soft parts ; extension is limited, when the ulna 
and humerus are nearly in line, by the tension of the soft parts and ligaments in 
front, and of the ventral portions of the lateral ligaments. The olecranon and 
coronoid processes do not arrest normal but only forced motion, by contact with 
the bottoms of their respective fossae. The head of the radius moves on the 
capitellum, and is in most complete contact with it in semiflexion, in which posi- 
tion it rotates best on the humerus in pronation and supination. Except pos- 
sibly to a very limited extent, owing to the slight incongruence of the surfaces, 
lateral motion is prevented by the lateral ligaments and the shape of the bones. 
Fig. 242.—E1b0w-joint, outer side. (Testnt.) RADIO-ULNAR ARTICULATIONS AND LIGAMENTS. 
223 
When the elbow is extended the tip of the olecranon lies on or just below a 
line connecting the two condyles: when flexed to a right angle it lies a little more 
than one inch below, and midway between these two points. 
5. Radio-ulnar Articulations and Ligaments. 
Two joints and an intermediate fibrous union connect the ulna and radius 
firmly together. 
(A) The Superior Radio-ulnar Articulation.—The rim of the head of the radius 
is held in contact with the small sigmoid cavity 
of the ulna by the strong encircling orbicular lig- 
ament. This forms four-fifths of a circle and is 
attached to the ventral and dorsal lips of the 
small sigmoid cavity, which completes the ring. 
It forms part of the capsule of the elbow-joint, 
and inserted into it are the external and parts 
of the ventral and dorsal portions of this capsule. 
Its lower border tightly girdles the neck of the 
radius. From this border membranous fibres 
pass to the neck of the radius loosely enough 
to allow of rotation of the radius on its long axis. 
It is lined by synovial membrane continuous with 
that of the elbow-joint. 
(B) The middle radio-ulnar union is accom- 
plished by two ligaments. (1) The oblique lig- 
ament is a flattened band, which passes obliquely 
downward and outward from the lower and outer 
part of the tuberosity of the ulna, at the base of 
the coronoid process, to the radius, directly below 
and behind the bicipital tuberosity. Below this 
ligament is a space through which the posterior 
interosseous vessels pass, and which is bounded 
below by the strong (2) interosseous membrane. 
The fibres of the latter pass mostly obliquely 
downward and inward from the interosseous 
border of the radius, commencing about one inch 
below the tuberosity, to the whole length of the 
interosseous border of the ulna. A few fibres on 
its dorsal surface are parallel with the oblique 
ligament, decussating with the other fibres. The 
interosseous space is widest in the middle third, 
and is wider in supination than in pronation, 
(C) The inferior radio-ulnar articulation, between the sigmoid cavity of the 
radius and the lower end of the ulna, is separated from the wrist-joint by the 
triangular fibro-cartilage. Phis thick plate is the most important structure in 
this joint, not only as the strongest bond of union between the two bones, but 
also in limiting their movements. It is attached by its base to the margin of the 
radius, which separates the sigmoid cavity from the carpal facet, and by its apex 
to the fossa at the base of the styloid process of the ulna externally. This liga- 
ment separates the lower end of the ulna, which rests on its upper smooth, concave 
surface, from the cuneiform bone of the carpus. Some scattered fibres from the 
two ends of the sigmoid cavity of the radius pass to the ventral and dorsal sur- 
faces of the lower end of the ulna above its articular surface. They are called 
anterior and posterior radio-ulnar ligaments, and are connected with the borders 
of the fibro-cartilage interiorly, and with the interosseous membrane superiorly, 
thus completing the capsule. Lining the capsule is the synovial membrane, which 
annular 
LIGAMENT 
Fig. 248.—Elbow-joint in sagittal sec- 
tion, showing the articular synovial sac 
and the bursae of the olecranon and the 
biceps. (Testut.) 224 
THE ARTICULATIONS. 
is remarkably loose. Besides extending upward between the radius and ulna, it 
lines the upper surface of the fibro-cartilage beneath the latter. 
The nerve-supply comes from the anterior and posterior 
interosseous nerves. 
Movements.—The upper end of the radius rotates on a 
longitudinal axis passing through its head and neck, while the 
lower end rotates around the head of the ulna, having the 
attachment of the apex of the fibro-cartilage as its centre 
(Fig. 244). The entire bone thus describes rather less than 
180° of a cone, with its apex above and its base below, its 
axis extending from the centre of the radial head to the outer 
side of the styloid process of the ulna. In these movements 
the radius carries the hand. The forearm is said to be supin- 
ated when its two bones lie nearly parallel and the dorsum of 
the hand looks backward, and pronated when the radius lies 
obliquely across the ulna, and the palm of the hand looks 
backward. 
The power of supination is much greater than that of 
pronation. In the above movements the ulna is thought by 
many to undergo slight circumduction. This implies a little 
lateral movement at the elbow, which, if it occurs at all, 
must be very trifling and due to a slight incongruence of the 
surfaces. Supination and pronation with a straight arm are 
apparently much increased by the rotation of the humerus at 
the shoulder. The interosseous membrane, from the direc- 
tion of its fibres, transmits the weight of the body from 
the ulna to the radius or the shock of a fall on the hands 
from the radius to the ulna. 
6. The Wrist-joint or Radio-carpal Articulation (Figs. 
245, 246). 
Fig. 244. —Mechan- 
ism of pronation and 
supination. (Testut.) 
The lower end of the radius and of the triangular fibro- 
cartilage presents a surface slightly concave transversely, as 
well as from before backward, which receives the correspondingly convex upper 
articular surfaces of the scaphoid, semilunar, and cuneiform bones. The latter 
surfaces are prolonged farther upon the dorsal than upon the palmar aspect. The 
ulna is excluded from the joint by the triangular cartilage ; and the pisiform bone 
of the first row does not enter into the articulation. The joint is condyloid in 
action. 
The rather loose capsule is described as four ligaments, which are, however, 
continuous. The internal lateral ligament is attached above as a rounded cord to 
the styloid process of the ulna, and spreads out below onto the cuneiform and 
pisiform bones. The external lateral ligament radiates from the summit of the 
radial styloid process onto the outer, back, and front surfaces of the scaphoid, some 
fibres being continued to the trapezium and os magnum. It is in relation with 
the radial artery and the extensor tendons of the thumb. The anterior ligament 
is broad, strong, and membranous. Its fibres pass for the most part obliquely 
from the anterior border of the lower end of the radius downward and inward to 
the palmar aspect of the scaphoid, semilunar, and cuneiform bones, especially the 
latter. Some fibres pass over to the os magnum. Another group of fibres passes 
more vertically from the ulnar styloid process to the semilunar and cuneiform bones. 
The posterior ligament, thinner and less strong than the anterior, is strengthened 
by the extensor tendons in relation with it. Its fibres also pass for the most part 
obliquely downward and inward from the dorsal border of the lower end of the 
radius to the first row of carpal bones, especially to the cuneiform bone. 
The synovial membrane lines the capsule between the articular surfaces. THE CARPAL ARTICULATIONS. 
225 
7. The Carpal Articulations. 
The bones of each of the two rows of the carpus, exclusive of the pisiform, 
are connected together by dorsal, palmar, and interosseous ligaments, passing 
nearly transversely between adjacent bones. The palmar are stronger than the 
dorsal ligaments. 
The joint between the pisiform and cuneiform bones is arthrodial, and has a thin, 
Fig. 245.—The articulations of the carpus. The synovial sacs are represented as distended. (Testut.) 
loose capsule lined by synovial membrane and strengthened by a fibrous band 
passing to the hook of the unciform, by another passing to the base of the fifth 
metacarpal, and by the insertion of the tendon of the flexor carpi ulnaris 
from above. 
The Medio-carpal or Transverse Carpal Articulation.—This joint is between 
the lower aspect of the first carpal row, which is concave except for the convex 
outer part of the scaphoid, and the upper surface of the second carpal row, con- 
cavo-convex from without inward. It is united by dorsal and palmar, internal 
and external lateral ligaments. The lateral ligaments, prolonged from the lateral 
ligaments of the wrist-joint, connect the lateral surfaces of the outer and inner 
bones of the two rows. The dorsal ligaments extend obliquely between the dorsal 
surfaces of the bones of the two rows. The stronger palmar ligaments are com- 
posed of fibres which for the most part radiate from the os magnum to the bones 
of the upper row. 
The synovial membrane is extensive. From the medio-carpal joint it sends 
two processes upward between the three bones of the upper row (exclusive of the 
pisiform); and between the four bones of the lower row 7 it sends three processes 
downward, which are continued into the four inner carpo-metacarpal and the 
three intermetacarpal articulations. It is nearly always separated from that of 
the wrist by the interosseous ligaments between the bones of the upper row, 
which make their convex upper surfaces uniformly even. 
J- -L _ -j v - 
Ine nerve-supply of the radio-carpal and carpal joints is from the ulna and 
median in front and the posterior interosseous behind. 226 
THE ARTICULATIONS. 
8. The Carpo-metacarpal and Intermetacarpal Articulations. 
The proximal ends of the inner four metacarpal bones are united to the inner 
three bones of the lower row of the carpus by dorsal and palmar ligaments. Of 
the dorsal ligaments the second and third metacarpals receive two or three each, 
the fourth two, and the fifth one. The latter is continuous internally with the 
palmar ligament, forming a partial capsule between the unciform and the fifth 
metacarpal, open externally. The palmar ligaments are weaker and less defined ; 
EXTERNAL LATERAL 
LIGAMENT 
-INTERNAL LATERAL 
LIGAMENT 
the third metacarpal receives three, the others one each. An interosseous liga- 
ment also connects the contiguous lower angles of the os magnum and the unciform 
with the adjacent surfaces of the third and fourth metacarpals, occasionally shut- 
ting off the synovial sac between the inner two metacarpals and the unciform 
from the common synovial sac, which is continuous with that of the carpal joints. 
A strong band from the trapezium to the outer aspect of the base of the second 
metacarpal helps to close the radial side of the joint of the latter. 
The bases of the inner four metacarpal bones are bound together by transverse, 
palmar, dorsal and interosseous ligaments. Their distal ends are united by trans- 
verse fibres passing between the margins of the palmar or glenoid ligaments of the 
metacarpo-phalangeal joints, and forming the transverse metacarpal ligament, 
which limits the separation of the metacarpal bones. The first metacarpal bone 
is free from the others at both ends. In the car'po-metacarpal joint of the thumb 
there is a thick, loose capsule, strongest dorsally and externally, which connects 
the margins of the articular surfaces of the trapezium and the first metacarpal. It 
is lined by a separate synovial membrane. 
Movements of a similar nature occur in the radio-carpal and medio-carpal 
joints. These movements are flexion and extension, abduction and adduction, and 
circumduction. Extension is more free than flexion in the radio-carpal joint, owing 
to the greater extent of the carpal articular surfaces dorsally than ventrally; but 
flexion is more free than extension at the medio-carpal and carpo-metacarpal joints, 
and it is the more free of the two motions in the wrist as a whole. Abduction and 
adduction, on an antero-posterior axis, occur principally at the radio-carpal joint. 
Adduction is much the more free, for the ulna does not extend as low as the 
radius, and does not help the external lateral ligament to check adduction as the 
radius does the internal lateral ligament to check abduction. The lack of rota- 
tion in the wrist is compensated for by the pronation and supination of the fore- 
Fig. 246.—Ligaments of the carpus, front view. (Testut.) THE ARTICULATIONS OF THE PELVIS. 
227 
arm, in which the hand rotates with the radius. In the medio-carpal joint, 
besides very free flexion, moderately free extension, and slight lateral motion, 
there is very limited rotation of the head of the os magnum and the unciform in 
the socket formed by the upper row, while the trapezium and trapezoid glide 
back and forth on the scaphoid. In the central carpo-metacarpal joints flexion 
and extension are slight. The fifth metacarpal is capable of more flexion than 
are the second, third, and fourth, and this flexion is directed outward as well as 
forward, producing opposition, or narrowing and hollowing of the hand, as in the 
closed fist. The movements of the first metacarpal are regulated principally by 
the saddle-shape of the surfaces, and consist of flexion and extension, abduction 
and adduction, and circumduction. Flexion is most free, and occurs obliquely 
forward and inward, thus allowing the opposing of the thumb to any of the 
fingers. Abduction is also very free, adduction less so. Movements between 
bones of the same row in the carpus are limited to slight gliding, which gives 
elasticity to the carpus, breaks jars and shocks, and thus strengthens the wrist. 
The cup-shaped bases of the proximal phalanges receive the rounded heads 
of the metacarpal bones to form a condyloid joint whose capsule is very weak 
behind, where the joint is covered by the expansion of the extensor tendons, but 
is reinforced laterally in front. The strong lateral ligaments are attached to the 
lateral tubercles and the depressions in front of them on the heads of the meta- 
carpal bones, and pass downward and forward to the lateral margins of the bases 
of the phalanges and to the palmar or glenoid ligaments. The anterior, palmar, 
or glenoid ligament is a thick fibro-cartilaginous plate, attached closely to the 
phalanx, loosely to the metacarpal. It is continuous laterally with the lateral 
ligaments and the transverse metacarpal ligament. Its palmar surface is slightly 
grooved for the flexor tendons, the sheaths of which are attached to its margins. 
Its dorsal surface helps to support the head of the metacarpal bone. In the 
thumb (and occasionally elsewhere) the fibro-cartilage ossifies into two sesamoid 
bones, receiving the insertion of the short muscles and forming a groove for the 
long flexor muscle. 
The inter phalangeal articulations are in every way similar, except for slight 
differences in the shape of the articular surfaces, which influence the action. A 
synovial membrane lines the inner surface of the connecting ligaments of each joint. 
Movements.—ln the metacarpo-phalangeal joint of the thumb motion is 
limited to flexion and extension, owing to the width of the surfaces. In the four 
other fingers abduction and adduction, in relation to the middle finger as the 
axis, are also quite free in the extended position. Flexion is the freest movement, 
owing to the greater extent of the articular facet in front and to the forward 
obliquity of the lateral ligaments. Flexion to a right angle and extension to a 
little beyond a straight line are permitted. Although abduction and adduction 
may occur separately, flexion and adduction and extension and abduction are 
associated together. The movements in the interphalangeal joints are limited to 
flexion and extension. Flexion is the more free for the same reason as above 
given, and in the proximal joint it exceeds a right angle; in the distal joint it 
may be rather less. The greater freedom of the thumb is due to the motion 
m the carpo-metacarpal rather than in the lower joints. 
9. Metacarpo-phalangeal and Interphalangeal Articulations. 
THE ARTICULATIONS OF THE PELVIS (Figs. 247, 248) 
The fifth lumbar is united to the first sacral vertebra by such joints and 
ligaments as are found between the vertebrae above, with the addition of two 
special accessory ligaments on each side, as follows : The lumbosacral ligament is 
The Articulations of the Pelvis with the Last Lumbar Vertebra 228 
THE ARTICULATIONS. 
a strong, triangular band, with its apex above and internally, where it is attached 
to the lower and front part of the transverse process of the last lumbar vertebra, 
from which it radiates downward and outward to the lateral surface of the base 
of the sacrum, blending with the anterior sacro-iliac ligament. The ilio-lum- 
bar ligament also is a strong triangular band, which passes from the apex of the 
transverse process of the fifth lumbar vertebra outward and somewhat backward, 
expanding to its attachment along the dorsal two inches of the inner lip of the 
iliac crest. It represents the thickened lower edge of the ventral layer of the 
lumbar fascia covering the quadratus lumborum, and gives origin to that muscle. 
It also helps to complete the dorsal boundary of the false pelvis. 
The Sacro-coccygeal and Intercoccygeal Articulations. 
The sacrum is united to the coccyx by an oval intervertebral disc, by an 
anterior and a stronger posterior sacro-coccygeal ligament, the continuations of the 
anterior and posterior common ligaments of the vertebrae; and by lateral liga- 
ments passing between the cornua of the two bones, and between the transverse 
processes of the first coccygeal vertebra and the lateral angles of the sacrum. 
The ligaments connecting the cornua of the two bones are sometimes called inter- 
articular, as the cornua represent articular processes ; but the ligament is prob- 
ably the continuation of the supraspinous ligament, which roofs over the lower 
end of the spinal canal. 
The several pieces of the coccyx are held together by the continuation of the 
anterior and posterior ligaments described above. Small discs of fibro-cartilage 
also connect them as long as they remain separate bones. 
The Sacro-iliac Joint. 
This is a synchondrosis in which the cartilage-clad auricular surfaces of the 
sacrum and ilium are bound together by a thin stratum of softer fibro-cartilage, 
which may contain a synovial-like cavity. 
In some cases also interosseous fibrous tissue 
partly binds the surfaces together, especially 
near the dorsal superior border, behind and 
above which the short transverse fibres of 
the deep part of the posterior sacro-iliac 
ligament sometimes receive the name of 
interosseous ligament. 
The anterior sacro-iliac ligament consists 
of a thin layer of fibres covering the front 
or pelvic surface of the joint, between the 
pelvic brim and the great sacro-sciatic notch. 
The posterior sacro-iliac ligament is very 
strong. The deeper bundles of fibres pass 
inward and slightly downward from the 
rough area above and behind the auricular 
surface of the ilium to the back of the lateral 
mass of the sacrum. A more dorsal or superficial band, sometimes called the long 
or oblique sacro-iliac ligament, passes from the back of the posterior superior iliac 
spine downward and slightly inward to the back of the third sacral vertebra. 
The cartilage connecting the auricular surfaces of this joint tears away, as one 
mass, from one or the other surface when the bones are forcibly separated. The 
sacro-sciatic ligaments also help to support this joint. 
The great or posterior sacro-sciatic ligament is thin and flat at its attached 
ends, narrower and thicker in the centre, which thus divides it into two triangles, 
of which the broader is attached to the posterior inferior iliac spine and the sides 
of the sacrum and coccyx, and the narrower to the inner margin of the ischial 
Fig. 247.—Sacro-iliac joint, cut in a plane 
parallel to that of the superior strait through 
the second sacral vertebra. (Testut.) THE SYMPHYSIS PUBIS. 
229 
tuberosity, sending its falciform process along the inner margin of the ischial 
ramus. The free, sharp edge of the falciform process is continuous with the poste- 
rior border of the ligament and with the obturator fascia. Some fibres pass over 
the tuberosity into the tendon of the biceps, of which this ligament represents the 
proximal continuation. The direction of this ligament is from above downward, 
outward, and slightly forward. It assists in bounding the pelvic outlet and the 
perineum laterally, and between it and the hip-bone is a large space subdivided 
by the small or anterior sacro-sciatic ligament into the great sacro-sciatic foramen 
POSTERIOR SACRO 
ILIAC LIGAMENT 
ILIO-LUMBAR LIGAMENT 
I SMALL SACRO-SCIATIC 
LIGAMENT 
Fig. 248.—Articulations of the pelvis, rear view. (Testut.) 
above and the small sacro-sciatic foramen below. This ligament lies in front of 
the preceding, and is triangular in form, its wide base attached to the side of the 
sacrum and coccyx, its apex to the ischial spine. Its deep surface is closely con- 
nected with the coccygeus muscle, of which it represents the thickened sheath. 
Through the great sacro-sciatic foramen pass the pyriformis muscle, and above the 
muscle the gluteal vessels and superior gluteal nerve, below- the muscle the sciatic 
and interna] pudic vessels and nerves, the inferior gluteal nerve, and the nerves 
to the obturator internus and quadratus femoris muscles. The small sacro-sciatic 
foramen is the smaller space below the small sciatic ligament. It is bounded 
behind by the great sacro-sciatic ligament and in front by the smooth cartilage- 
clad surface between the ischial spine and tuberosity, over which passes the obtu- 
rator internus muscle. The internal pudic vessels and nerve and the nerve to 
the obturator internus pass in through this foramen. 
The Symphysis Pubis. 
The opposed median surfaces of the pubic bones are each covered with a thin 
layer of hyaline cartilage, united into a single interpuhic disc by an interposed 
layer of fibro-carlilage. The latter is broader in front and below, and bulges 
especially behind. It is attached to the surrounding ligaments on all sides, and 
often contains a cleft. This cleft or cavity is usually nearer the upper and back 
part, does not reach the surface, is not lined by synovial membrane, and is larger 
in the female, though not greatly affected by pregnancy. A fibrous capsule sur- 
rounds the joint, which is further strengthened by tendinous attachments. The 
superior and posterior ligaments are but slightly marked transverse fibres strength- 230 
THE ARTICULATIONS. 
ening the periosteum. The anterior ligament is stronger, and consists of deep 
transverse fibres and superficial oblique, decussating fibres connected with the 
tendons of the muscles arising from the body of the os pubis. The inferior or sub- 
pubic ligament is a thick triangular mass of transverse and curved fibres, round- 
ing off the subpubic angle of the pubic rami, which forms the ventral angle of 
the pelvic outlet. 
Movements, Mechanism, etc.—Owing to the thickness of the disc between the 
fifth lumbar vertebra and the sacrum, movements are more free here than between 
any two lumbar vertebrae, and especially flexion and extension, which occur 
in sitting or in rising from the sitting posture. The inclination of the pelvis 
depends partly upon the sacro-vertebral angle between the sacrum and the spine, 
but also, and in great part, on the obliquity of the hip-bones to the sacrum at the 
sacro-iliac joint. At the sacro-iliac joint there is no movement: it merely serves 
to break shocks. In the erect position the base of the sacral wedge is directed so 
largely forward, and the ventral or broader surface of the sacrum is directed so 
largely downward, that the sacrum is not held in place by virtue of its wedge 
shape, but is suspended from the ilia by the very strong posterior sacro-iliac liga- 
ments in such a way that the greater the pressure the tighter is the union. The 
tendency to rotation of the sacrum, due to the weight of the spine transmitted to 
its forward projecting base, is resisted above by the ilio-lumbar and below by the 
sacro-sciatic ligaments (the former directed backward, the latter forward from the 
sacrum). At the pubic symphysis there is only a slight yielding of the cartilage, 
which may occur at childbirth, when the cartilage is softer and more vascular ; 
but the decussating tendinous fibres of the abdominal muscles, which cross it in 
front, would tend to brace the bones more tightly together by their contraction 
during labor. The sacro-coccygeal joint allows of flexion and extension. In 
defecation and parturition the coccyx is pushed backward. This joint may be 
ankylosed in adult life, but less often in females than in males, and its mobility 
seems to increase during pregnancy. 
THE ARTICULATIONS OF THE LOWER LIMB 
1. The Hip-joint (Figs. 249-251). 
In this typical ball-and-socket joint the round head of the femur is received 
into the acetabulum of the hip-bone. The cartilage-clad surface of the acetabulum 
is horseshoe-shaped, broader above and behind, and deficient below at the coty- 
loid notch and in the depression at the bottom of the acetabulum, which is occu- 
pied by a mass of fat covered by synovial membrane—the so-called synovial 
(Haversian) gland. The articular cartilage of the head of the femur is thicker 
above, where it bears the weight of the body, and is only wanting a little behind 
and below the centre at the depression for the ligamentum teres. The acetabular 
rim is completed below by the transverse and decussating fibres of the transverse 
ligament, which bridges over the cotyloid notch, and converts it into a foramen 
through which articular vessels pass. This ligament blends with and helps to 
support the cotyloid ligament, a thick fibro-cartilage, triangular on section, firmly 
attached by a broad base to the rim of the acetabulum, which it deepens to more 
than a hemisphere. Its concave inner surface and thin free margin tightly em- 
brace the head of the femur a little beyond its greatest circumference and, aided 
by atmospheric pressure, hold it in place when its ligaments are divided. Its 
fibres pass obliquely from without inward, and its outer convex surface is in con- 
tact with the capsular ligament. It is covered on both sides by synovial mem- 
brane. 
The capsular ligament is one of the strongest in the body. Surrounding the 
joint, it is attached to the pelvis at or near the rim of the acetabulum, outside 
of the cotyloid ligament, and to the transverse ligament. On the femur it is 
attached in front to the anterior intertrochanteric line, from the tubercle above to THE HIP-JOINT. 
231 
the level of the lower part of the small trochanter below ; behind and below, 
to the neck, one-half to two-thirds of an inch internal to the posterior intertro- 
chanteric line; and above, at the base of the great trochanter, internal to the 
digital fossa. The innermost capsular fibres are reflected upon the neck of the 
femur toward the articular margin, blending with the periosteum and forming 
three flat bands or retinacula, one behind and one at either end of the anterior 
intertrochanteric line. The capsule is somewhat loose, and its fibres run longitu- 
dinally with some circular fibres interwoven. The circular fibres are found most 
abundantly behind and below, where they form a band arching around the neck 
of the femur. The longitudinal fibres are much thickened in parts by accessory 
bands, inseparable from the capsule, which greatly strengthen the joint. Many 
of these bands are derived from the fascial sheaths of the surrounding muscles, 
which are—in front, the ilio-psoas, partly separated from the capsule by a bursa; 
internally, the pectineus; below and behind, the obturator externus; behind, the 
CARTILAGE- 
COTYLOID LIGAMENT- 
CAPSULAR LIGAMENT- 
SYNOVIAL MEMBRANE- 
CARTILAGE 
rATTY CUSHION 
ARTERY AND VEIN 
ENTERING AND LEAVING 
LIGAMENTUM TERES 
Fig. 249.—Hip-joint in coronal section. (Testut.) 
obturator interims with the two gemelli and the pyriformis ; above or externally, 
the rectus femoris and the gluteus minimus. The obturator interims acts like a 
powerful strap at the back of the joint. 
Of the three principal accessory bands, the ilio-femorcd band is the strongest and 
most important. Superiorly attached to the ilium, below and behind the anterior 
inferior spine, it spreads out triangularly to the anterior intertrochanteric line 
°t the femur. Its inner and outer borders form two very strong bands, between 
which the capsule is thinner, so as sometimes to suggest the name of the inverted 
'-ligament given it by Bigelow. This ligament is rarely torn, and forms the 
fulcrum for the manipulation in reducing dislocations of the thigh. The outer 
oi’ upper part of this band, passing to the upper end of the anterior border of 
the great trochanter, is sometimes described as the ilio-trochanteric ligament. 
_ fhe pubo-femoral band is the weakest, and passes from between the pectineal 
eminence and the cotyloid notch to the neck of the femur, above and behind the 232 
THE A B TIC ULA TIONS. 
inner band of the ilio-femoral ligament. It is derived from the fascia between 
the pectineus and the obturator externus. The capsule is thinnest between 
this and the ilio-femoral band, where it is perforated by an opening between the 
synovial cavity and the bursa beneath the psoas. The ischio-femoral band con- 
sists of strong fibres from the ischium just below the acetabulum, which curve 
upward and outward to the base of the great trochanter internal to the digital 
fossa. In flexion of the thigh they pass almost straight to their femoral attach- 
ment. The capsule is weak dorsally below this band, where it usually tears in 
dislocation. Between this and the ilio-femoral band superiorly the capsule is 
strong, and is further strengthened by bands from the gluteus minimus and from 
the reflected tendon of the rectus. From the latter the tendino-trochanteric band 
passes to the upper end of the vastus externus muscle. 
Fig. 250.—Hip-joint, front view. The cavity is distended artificially. (Testut.) 
The ligamentum teres (round ligament) is not round, but a triangular, flat 
interarticular band attached by its apex to the upper half of the depression on 
the head of the femur, and by its base to the transverse ligament and the margins 
of the cotyloid notch, the ischial portion being the stronger. It is surrounded 
by synovial membrane, and represents a migrated portion of the pectineus muscle. 
It conveys a small branch of the obturator artery to the head of the femur. It 
is torn in dislocation of the femur. 
The synovial membrane lines the inner surface of the capsule, from which it 
is reflected onto the neck of the femur as far as the articular margin, and onto 
the two free surfaces of the cotyloid ligament, thence being continued to the pad 
of fat at the bottom of the acetabulum, and as a tubular covering of the liga- 
mentum teres. 
Nerves.—The obturator, accessory obturator, anterior crural, and great sciatic, 
or the sacral plexus, supply the joint. 
Movements.—All the movements of a ball-and-socket joint are permitted. 
The obliquity of the neck of the femur allows flexion and extension to take 
place by a rotation of the head without its cartilage-clad surface leaving the THE KNEE-JOINT. 
233 
socket, thus securing strength for these, the most important movements. Exten- 
sion is limited by the strong ilio-femoral band, which helps to maintain the erect 
position without muscular exertion by preventing over-extension in standing, 
in which position the centre of gravity descends behind the centre of the joint. 
Flexion takes place through about 140°, until checked by the contact of the thigh 
and abdomen if the knee is flexed; otherwise, it is checked at about 90° by 
Fig. 251.—Hip-joint, front view. The capsular ligament has been largely removed. (Testut.) 
the hamstring muscles. In all the other movements the articular portion of the 
head projects beyond the cotyloid rim on the side opposite to that toward which 
the movement takes place. Abduction is limited by the pubo-femoral band, 
adduction by the outer part of the ilio-femoral band and the upper part of the 
capsule. Rotation takes place on a vertical axis passing from the head above to 
the lower extremity of the femur below. (This axis is not coincident with that 
of the shaft.) Inward rotation is limited by the ischio-femoral band, outward 
rotation by the ilio-femoral band (its inner part during extension, its outer during 
flexion). The ligamentum teres is put on the stretch in flexion with abduction 
or outward rotation, or both, but it is too weak to be of use in resisting these 
movements or in strengthening the joint. 
2. The Knee-joint (Figs. 252-255). 
This, the largest joint in the body, is a modified hinge-joint, whose bony articu- 
lar surfaces (the condyles and trochlear surface of the femur, the tuberosities of the 
tibia and the patella) are not adapted to one another except by means of soft parts 
and the interposed fibro-cartilages. The knee is very superficial, and is strong 
only by reason of the number and strength of the ligaments and surrounding 
tendons and muscles, which, as well as the width of the bony surfaces, resist 
dislocation in spite of the leverage of the longest two bones in the body. It 
represents two morphologically distinct joints, the patello-femoral and the tibio- 
femoral, the latter also composed of two laterally placed joints, the median division 
between which is represented by the crucial and mucous ligaments. The synovial THE ARTICULATIONS. 
membrane of these joints has blended into one. The fibrous capsule of the knee is 
strengthened in places by strong bands derived from the surrounding tendons, 
closely adherent to its outer surface, and known as the external (superficial) set of 
ligaments. 
1. The internal lateral ligament is a long, flat, strong band which extends from 
the internal tuberosity of the femur 
(close to the adductor magnus ten- 
don, of which it was originally a con- 
tinuation) to the inner surface and 
border of the tibia, descending below 
the level of the tubercle. Blended 
above and internally with the fibro- 
cartilage and capsule, it is separated 
from the latter below, and bridges 
over part of the semimembranosus 
tendon and the inferior internal ar- 
ticular vessels. Superficially, it is 
separated by a bursa from the ten- 
dons of the sartorius, gracilis, and 
semitendinosus. 
2. The external lateral ligament 
extends downward and slightly back- 
ward as a rounded cord from the ex- 
ternal tuberosity of the femur to the 
middle of the outer surface of the 
head of the fibula. It crosses super- 
ficially over the popliteus tendon and 
the external inferior articular vessels, 
and is separated by a bursa from the 
biceps tendon, which splits to em- 
brace it. It is continuous below 
with the origin of the peroneus lon- 
gus, of which it represents the detached femoral origin. A little behind this 
ligament is the broader but less constant and defined short or posterior external 
lateral ligament, which extends from the external condyle of the femur, in con- 
nection with the external gastrocnemius tendon, to the styloid process of the 
fibula. It blends with, and is really a portion of, the posterior ligament. Both 
internal and external lateral ligaments are situated behind the centre of the joint. 
3. The posterior ligament proper is a strong flat band which ascends obliquely 
upward and outward as an expansion from the semimembranosus tendon, from 
the back of the inner tuberosity of the tibia, to the external condyle of the femur, 
joining the outer head of the gastrocnemius. The rest of the so-called posterior 
ligament underlies this oblique portion, and is a part of the capsule which occupies 
the interval between the lateral ligaments behind. It is a broad membrane com- 
posed of nearly vertical bundles of fibres, which pass from the upper margins of 
the intercondylar notch and of the articular surfaces of the femur to the dorsal 
margin of the head of the tibia. 
4. The ligamentum patella is the strong, flat infrapatellar tendon of the quadri- 
ceps extensor, extending from the apex and lower border of the patella to the 
lower part of the tubercle of the tibia (where it descends lower on the outer side). 
A synovial bursa separates the ligament from the upper part of the tubercle, above 
which a mass of fat separates it from the synovial membrane. 
5. The capsular ligament is seen only in the intervals between the above liga- 
ments. Behind it is thickened to form most of the posterior ligament, in front it 
is wanting beneath the patella and its tendons, between which and the lateral 
ligaments it is strengthened by the fascia lata and the lateral fibrous expansions 
of the quadriceps extensor tendon. These expansions, passing down from the vasti 
\ ANTERIOR CRU- 
■T CIAL LIGAMENT 
..POSTERIOR CRU- 
CIAL LIGAMENT 
Fig. 252.—Knee-joint in sagittal section. (Testut.) THE KNEE-JOINT. 
235 
muscles, are attached to the sides of the patella1 and the ligamentum patellae, and 
to the tibia along the oblique lines extending from the tubercle to the inner and 
outer tuberosities. They reach as far as the lateral ligaments. Externally, the 
ilio-tibial band of the fascia lata, attached to the external one of the above oblique 
lines, adds largely to the strength of the capsule. The capsule is therefore made 
up of two or three layers, and between the deeper layer, or the capsular mem- 
POPLITEUS > 
EXTERNAL LATERAL 
LIGAMENT 
CARTILAGE 
EXTERNAL LATERA 
LIGAMENT 
.INTERNAL LATERAL 
INNER HAMSTRING 
Fig. 253.—Knee-joint, front view. Part of the ligaments have been removed on the right side. (Testut.) 
brane proper, and the outer layers there often exists a thin layer of fatty tissue. 
The capsular membrane is attached to the femur and tibia not far from their 
articular margins, and is adherent to the semilunar cartilages. 
Of the so-called internal (deep) set of ligaments, most may be well seen by 
dividing the quadriceps tendon above the patella, continuing the section laterally 
mid downward to the lower ends of both lateral ligaments, and turning down 
the flap thus made. 
6. Synovial Ligaments.—From the synovial membrane lining the pad of fat 
behind the ligamentum patellae two thin lateral folds of membrane extend upward, 
one on each side of the patella, known as the alar ligaments. From the middle 
°f the surface of the pad a flattish fold, the ligamentum mucosum, extends back- 
ward and upward to the front of the intercondylar notch. It represents the 
remains of the synovial partition between the two halves of the tibio-femoral joint 
and between the patello-femoral and tibio-femoral joints. 
On dividing the ligamentum mucosum we see 
7. The anterior crucial ligament, which extends upward, backward, and outward 
trom its lower attachment to the inner half of the depression in front of the spine 
of the tibia, and between the fore ends of the semilunar cartilages, to the hind 
part of the inner surface of the outer condyle of the femur. 
8. The posterior crucial ligament is stronger, shorter, and more vertical than 
the anterior. From behind the tibial spine, from the popliteal notch, and 
receiving fibres from the posterior cornu of the external semilunar cartilage, its 
1 Forming what has been called the lateral patellar ligaments. 236 
THE ARTICULATIONS. 
fibres ascend slightly forward and inward to the front of the outer side of the 
internal condyle of the femur. Behind and below it is adherent to the posterior 
ligament. It crosses the anterior crucial ligament on its inner side, and is blended 
with it below, but separated from it above by a V-shaped space. The synovial 
membrane is prolonged over them both. 
The external and internal semilunar fibro-cartilages are two crescentic plates, 
of a dense, compact structure, attached by 
their thick, convex, outer margins to the 
inside of the capsule. They rest upon the 
circumferential portions of the upper arti- 
cular facets of the tibia, covering a little 
less than two-thirds of these surfaces. They 
increase the concavity for articulation with 
the femur by a gradual thinning to their 
concave, free inner borders. Their upper, 
concave, femoral, and lower flattened tibial 
surfaces are free and covered by synovial 
membrane. They taper to their attached 
ends or cornua, which are purely fibrous, 
and are fastened in front of and behind the 
tibial spine, the cornua of the external car- 
tilage being within those of the internal. 
The external semilunar cartilage is therefore 
more circular, the internal is more oval and 
longer from before backward. The external 
is also more movable, from the close approximation of its cornua and from the 
greater laxity of the part of the capsule to which it is attached. Its outer margin 
is grooved behind, and separated from the capsule by the popliteus tendon, the 
bursa surrounding which connects with the joint above and below the cartilage. 
The transverse ligament is a variable transverse band which connects the outer 
borders of the two semilunar cartilages in front. 
Coronary ligament is a name applied to that part of the capsule between its 
attachment to the semilunar cartilages above and the head of the tibia below, 
which holds the cartilages in apposition with the tibia. 
The synovial membrane, the largest in the body, lines the capsule of the joint. 
Above the patella, in front of the femur and beneath the extensor tendon, it 
forms a large pouch, communicating in most cases with a bursa above it, which 
lies between the extensor tendon and the front surface of the femur, above the 
attachment of the capsular membrane. Traced downward, it is found to line the 
capsule until it meets the semilunar cartilages, where it is reflected onto their 
upper surfaces, around their free margins, onto their lower surfaces, and so back 
to the portion of the capsule called the coronary ligament, which it lines down to 
its tibial attachment. From the capsule behind and the semilunar cartilages 
below this membrane is reflected onto the crucial ligaments, which it invests, 
except behind and below, and thus shuts them out of the synovial cavity. It also 
forms the alar and mucous ligaments. Synovial bursce beneath and between the 
gastrocnemius and semimembranosus internally, and beneath the popliteus tendon 
externally, may connect with the synovial cavity. 
The nerve-supply comes from the internal and external popliteal, the anterior 
crural, and the obturator nerves. 
Movements.—The principal movements are those of flexion and extension, 
which result from a combination of gliding and hinge rotation, not on a fixed 
axis, but on one which shifts with the points of contact from behind forward in 
extension, and vice versa in flexion. The points of contact of the articular surfaces 
are constantly changing from the flattish lower surface of the femoral condyles in 
extension to their more sharply curved hind surfaces in flexion, and from the fore 
part of the tibial surfaces in extension to their hind part in flexion. The looseness 
Fig. 254—The semilunar cartilages of the 
right knee-joint. (Testut.) THE TIBIO-FIB ULAR UNION. 
237 
of attachment of the semilunar cartilages allows them to adapt themselves to the 
differently curved surfaces of the femur. 
As the knee is moved from the flexed to the extended position the crucial 
ligaments become tense, and keep pulling back 
the articular surface of the tibia, so that the 
points of contact of both tibia and femur are 
shifted forward. This relaxes the ligaments 
and allows the motion to continue. The ante- 
rior crucial ligament also resists the tendency 
of the extensor muscle to displace the tibia 
forward in extension. In flexion the crucial 
ligaments cause a shifting of the points of con- 
tact in the opposite direction, and the posterior 
crucial ligament prevents the tibia from being 
pulled backward by the flexor muscles. 
At the end of extension there is a slight 
outward rotation of the tibia and foot on a ver- 
tical axis, and at the commencement of flexion 
a similar rotation in the opposite direction. 
This is due in part to the greater length of the 
inner condyle, onto the outwardly directed fore 
part of whose articular surface the inner facet 
of the tibia glides forward in outward rotation 
at the end of extension, and backward in in- 
ward rotation at the beginning of flexion. Ex- 
tension is checked by the lateral and posterior 
ligaments and the anterior crucial ligament. 
Flexion is checked by contact of the soft parts 
at about 135°. In extreme flexion the liga- 
mentum patellae, the fore part of the capsule, 
and the posterior crucial ligaments are tight- 
ened. The relaxation of the ligaments in the 
partly flexed position allows an inward and out- 
ward rotation, on a vertical axis, in which the 
semilunar cartilages slide back and forth on the tibia. This rotation is impossible 
in the extended position owing to the tension of the ligaments. Rotation inward 
is checked by the anterior crucial ligament, rotation outward by the lateral liga- 
ments. The erect position, in which the line of gravity descends in front of the 
knee, is maintained, in great measure, without muscular effort by the resistance 
offered to over-extension by most of the ligaments. 
The movements between the patella and the femur are a combination of sliding 
and coaptation. In moving from the extended to the flexed position the lower, 
middle, and upper parts of the patellar facets are successively in contact with the 
upper, middle, and lower parts of the trochlear surface of the femur. In extreme 
flexion a narrow vertical surface on the inner side of the patellar facet is in con- 
tact with the fore part of the outer border of the inner condyle of the femur, the 
patella being turned more outward by the external condyle, against which its 
upper and outer part rests. 
Pig. 255.—Knee-joint, outer side. The 
synovial sacs are artificially distended. 
(After Poirier.) 
3. The Tibio-fibular Union 
The tibia and fibula are united at their upper and lower ends by joints, and 
between them by an interosseous membrane. 
A. The Superior Tibio-fibular Articulation.—In this joint the oval, flattened, 
oblique articular surface on the head of the fibula is connected with that on the 
external tuberosity of the tibia by a capsular ligament, strengthened in front and 
behind by fibres which pass downward and outward from the tibia to the fibula— 238 
THE ARTICULATIONS. 
the anterior and posterior superior tibio-fibular ligaments. The capsule is not 
infrequently imperfect above and behind, where the synovial cavity of this joint 
may communicate with that of the knee through the medium of the bursa beneath 
the popliteus tendon. 
B. The Interosseous Membrane extends between the outer border of the tibia 
and the interosseous border of the fibula as a firm aponeurotic membrane, whose 
fibres descend for the most part from the tibia to the fibula, wTith a few in the 
opposite direction. It is separated from the superior tibio-fibular joint by an 
oval opening through which the anterior tibial vessels pass, and below it is con- 
tinuous with the inferior interosseous ligament, being perforated by the anterior 
peroneal vessels. It serves mainly for muscular attachment. 
C. The Inferior Tibio-fibular Articulation (Fig. 256).—The rough triangular 
surfaces on both bones, formed by the bifurcation of their interosseous borders, 
are firmly united by the short, strong, obliquely transverse fibres of the inferior 
interosseous ligament, to within one-fourth an inch of the facets for the astragalus, 
where two narrow articular facets, continuous with those for the astragalus, are 
in contact. The union is strengthened in front and behind by the anterior and 
posterior inferior tibio-fibular ligaments, flat bands which extend across the joint 
from the lower end of the tibia obliquely outward and downward to the lower 
end of the fibula. 
The transverse ligament is a thick, strong band, below the posterior liga- 
ment, which extends from the posterior border of the lower articular surface 
F'ASCICULUS 
INTEROSSEOUS) 
LIGAMENT 
Fig. 256.—Tibio-tarsal and calcaneo-astragaloid articulations, in coronal section. The synovial sacs are 
distended. (Testut.) 
of the tibia outward, downward, and a little forward to the inner surface of the 
external malleolus, in and above the fossa. The synovial membrane, continuous 
with that of the ankle, extends up between the bones as far as the inferior inter- 
osseous ligament. 
The movements in these joints consist in a slight yielding or vertical sliding, 
which is allowed by the obliquity of the ligaments. The upward sliding of the 
fibula is accompanied by a slight widening of the tibio-fibular mortice, which 
occurs in flexion of the ankle. The inferior interosseous ligament is put to a 
great strain in the injuries producing “ Pott’s fracture.” THE ANKLE-JOINT. 
239 
4. The Ankle-joint (Figs. 256, 257). 
The ankle is a hinge-joint, in which the articular surfaces of the lower end 
and internal malleolus of the tibia and of the external malleolus of the fibula 
form a mortice, into which the upper and lateral facets of the astragalus fit as a 
tenon. The transverse ligament helps to complete the tibio-fibular socket behind. 
The capsule, strengthened and protected by the strong tendons passing over it, is 
divided, for description, into the following ligaments : 
The internal lateral or deltoid ligament is a strong, flat, triangular band which 
radiates from the lower and ventral borders of the internal malleolus downward and 
backward to the rough inner surface of the astragalus, downward to the sustentacu- 
lum tali of the os calcis, and downward and forward to the navicular and the 
margin of the inferior calcaneo-scaphoid ligament. A so-called deep portion 
descends from the notch on the lower border of the malleolus to the depression on 
the inner surface of the astragalus. 
The external lateral ligament presents three separate diverging bands : 1. The 
POST. INF. TIB. 
W FIB. LIG. 7 
POSTERIOR 
FASCICULUS 
middle cuneiform 
PERONEUS LONGUS 
'PERONEUS BREVIS 
-PERONEUS BREVIS 
Fig. 257.—Tibio-tarsal articulation, outer side. The cavity is artificially distended. (Testut.) 
anterior fasciculus, short and ribbon-like, passes from the ventral border of the 
external malleolus obliquely forward and upward to the astragalus, in front of its 
external lateral facet. 2. The middle fasciculus, strong and round, descends slightly 
backward from the tip and the fore part of the outer surface of the external mal- 
leolus to the middle of the outer surface of the os calcis. 3. The posterior fasci- 240 
THE ARTICULATIONS. 
cuius is the strongest, and passes from the hind border and the fossa on the inner 
side of the external malleolus almost horizontally inward to the outer surface of 
the astragalus, behind the facet, and to its external tubercle. 
The anterior ligament is a thin, loose membrane between the lateral ligaments 
in front. It is attached above to the ventral margin of the lower end of the 
tibia, above a slight transverse groove, and below to the rough upper aspect of 
the head of the astragalus. A mass of fat beneath it rests in the groove of the 
neck of the astragalus. 
The posterior ligament is very thin and weak, and consists of scattered oblique 
fibres between the dorsal margins of the articular surfaces of the tibia and the 
astragalus. The flexor longus hallucis tendon serves largely as a posterior 
ligament. 
The synovial membrane is very loose on the anterior and posterior ligaments, 
forming folds between the tibia and the astragalus. It forms a short cul-de-sac 
between the tibia and fibula, in addition to lining the ligaments of the ankle. 
Nerves.—Branches from the anterior and posterior tibial and the internal 
saphenous supply the joint. 
The movements of the ankle are flexion and extension through a range of less 
than 90°. Flexion or dorsal flexion, in which the dorsum of the foot and toes 
approaches the leg, is limited by the posterior ligament, the posterior parts of the 
lateral ligaments, and by the contact of the ventral margin of the lower end of 
the tibia with the neck of the astragalus. In extreme flexion the fibula is slightly 
raised and spread somewhat from the tibia, accommodating the wide fore part of 
the upper articular surface of the astragalus. Extension or plantar flexion, where 
the toes are brought nearly into line with the leg, is limited by bony contact 
behind and by the tension of the anterior ligament and the anterior parts of the 
lateral ligaments. Extreme extension is accompanied by some adduction and 
slight supination of the foot, which probably occurs in the tarsal joints ; for, 
although in this position the narrow dorsal part of the astragalus facet is less 
tightly held in the wide fore part of the tibio-fibular mortice, yet probably no 
lateral motion normally occurs except from external force. In the erect posture 
the line of gravity falls a little in front of the axis of the ankle, which is directed 
from within outward and backward. This obliquity of the axis helps to secure 
stability in the erect attitude, which is otherwise dependent on muscular action. 
The lateral ligaments are often partly ruptured in sprains of the ankle and in 
“ Pott’s fracture.” 
The articulations of the astragalus consist of (1) a posterior and external astra- 
galo-calcaneal joint, and (2) an anterior and internal caleaneo-astragalo-scaphoid 
joint, the fore part of which, or the astragalo-scaphoid portion, is partly sup- 
ported and encapsulated by the two calcaneo-scaphoid ligaments uniting the os 
calcis and scaphoid bone. 
(1) In the posterior astragalo-calcaneal joint the dorsal pair of facets between 
these two bones are held together by a capsule, split up into several distinct slips 
as follows : An internal astragalo-calcaneal hand, passes from the internal tubercle 
of the astragalus, on the inner side of the groove for the flexor longus hallucis 
tendon downward and forward to the back of the sustentaculum tali. The posterior 
astragalo-calcaneal ligament, attached above to the external tubercle of the astra- 
galus, spreads out onto the adjacent upper and inner surfaces of the os calcis. 
An external ligament connects the two bones beneath and in front of the middle 
slip of the external lateral ligament of the ankle, with which its fibres are 
parallel. The interosseous ligament is a strong band of fibres passing vertically 
between the grooves of the astragalus and os calcis, which together form the 
sinus pedis. It separates the two articulations between the astragalus and the os 
calcis, and consists of imperfectly separate layers, one of which serves as the 
anterior ligament of the posterior joint, and the other as the posterior ligament 
5. The Tarsal Joints (Figs. 256-259). THE TARSAL JOINTS. 
241 
of the anterior joint. Furthermore, those parts of the lateral ligaments of the 
ankle which reach the os calcis help to unite it with the astragalus. 
(2) The calcaneo-astragalo-scaphoid joint is between the anterior facet on the 
upper surface of the os calcis and the facets on the lower surface of the head and 
neck of the astragalus, and between the head of the astragalus and the navicular. 
The bones are held together by the following ligaments, in addition to the interos- 
seous ligament, which limits the joint postero-externally. 
Calcaneo-scaphoid Ligaments.—The inferior or internal ligament is broad, thick, 
and partly fibro-cartilaginous. It firmly unites the front and inner edges of the 
sustentaculum tali with the inferior surface of the navicular and its inner surface 
behind the tubercle. Its upper surface is smooth and articular, and completes the 
socket for the head of the astragalus below and internally. The upper part of its 
under surface presents a smooth facet for the tendon of the tibialis posterior, which 
aids in supporting the head of the astragalus. It is blended internally with the 
internal lateral ligament of the ankle, and externally and below with the external 
or superior calcaneo-scaphoid ligament. The strong fibres of the latter ligament 
pass obliquely forward and inward from the fore part of the upper surface of the 
os calcis, external to its front upper facet, to the outer surface of the scaphoid. 
It limits botli the anterior astragalo-calcaneal and the astragalo-scaphoid joints 
externally. The capsule is completed superiorly by the astragalo-scaphoid liga- 
ment, a broad, thin, membranous band, which converges from the upper surface 
of the head of the astragalus to the upper surface of the navicular. 
The synovial membrane of the posterior astragalo-calcaneal and that of the 
calcaneo-astragalo-navicular joints are distinct, and separated from one another by 
the interosseous ligament. 
The calcaneo-cuboid articulation, between the contiguous facets of the os calcis 
and the cuboid, forms, with that between the astragalus and scaphoid, the medio- 
tarsal, transverse tarsal, or Chopart’s joint. The surfaces are held together by the 
following ligaments : The inferior calcaneo-cuboid ligaments consist of two por- 
INTEROSSEOUS ASTRAGALO 
CALCANEAL LIGAMENT 
' INFERIOR CALCANEO- 
SCAPHOID LIGAMENT 
SUPERIOR CALCANEO- 
SCAPHOID LIGAMENT 
SUPERIOR CALCANEO- 
CUBOID LIGAMENT 
Fig. 258.—Medio-tarsal joint, viewed from above, the astragalus having been removed. (Testut.) 
tions, known as plantar ligaments. The superficial part, or long plantar ligament, 
arises from the under surface of the os calcis between the tubercles, and extends 
forward to the oblique ridge on the under surface of the cuboid. From this ridge 
some fibres continue forward, bridging over and converting into a canal the groove 
for the peroneus longus tendon, and are attached to the bases of the outer four meta- 
tarsal bones. The deep portion, or short plantar ligament, attached to the under 
surface of the os calcis, to and in front of the anterior tubercle, extends forward 
and inward to the depression on the under surface of the cuboid behind the 242 
THE ARTICULATIONS. 
oblique ridge. The superior calcaneo-cuboid ligament connects the adjacent parts 
of the upper surfaces of the two bones, blending externally with the outer part of 
the short plantar ligament, and internally with the internal or interosseous calcaneo- 
cuboid ligament. This strong band connects the inner surfaces of the two bones 
near their articular margins, lying deeply in the hollow between the os calcis and 
astragalus, where it is closely connected with the external calcaneo-scaphoid 
ligament. 
The synovial membrane is separate from that of the other tarsal joints. 
Movements.—The movements of the fore part of the foot on the hind part 
take place at the medio-tarsal joint. The movements at the calcaneo-astragaloid 
joints are inversion and eversion (turning of the sole inward and outward 
respectively), and adduction and abduction (the movement of the front of the 
foot to and from the median line respectively). Both of these forms of move- 
ment occur also in the medio-tarsal joint, and besides them there is here quite 
free flexion and extension around an oblique axis, extending from within outward 
and somewhat backward and downward. Flexion is simultaneous with extension 
at the ankle, and extension, which is more limited, is simultaneous with flexion 
at the ankle. Thus, the variety and range of motion of the foot are increased 
beyond the limited flexion and extension allowed in the ankle. The astragalo- 
scaphoid joint is of the ball-and-socket variety, but, owing to the connection of 
the scaphoid and cuboid bones, its motions are so restricted by the concavo-convex 
calcaneo-cuboid joint that adduction and inversion are combined with flexion and 
abduction, and eversion with extension, the latter being limited by the plantar 
ligaments. The calcaneo-scaphoid ligaments also limit motion here. At the 
medio-tarsal and astragalo-calcaneal joints increase of the arch, combined with 
adduction and inversion, or decrease of the arch with abduction and eversion, may 
occur, leading respectively to club- or flat-foot, when for any reason these posi- 
tions are exaggerated and permanent. 
In the Cubo-scaphoid joint the cuboid and navicular are united by—(l) a dor- 
sal ligament, passing obliquely forward and outward from the scaphoid to the 
cuboid ; (2) a plantar ligament, similarly disposed on the plantar surface ; and (3) 
a strong interosseous ligament, connecting their contiguous surfaces, which, when 
they touch, present small articular facets, whose connecting ligaments are lined 
by an extension of the scapho-cuneiform synovial membrane. 
The Scapho-cuneiform Articulation.—The navicular is united in one continuous 
joint to the three cuneiform bones in front of it by (1) strong dorsal ligaments 
from the upper surface of the scaphoid to that of each of the three cuneiform 
bones; and (2) by plantar ligaments similarly disposed beneath and continuous 
with the fibres of the tibialis posterior tendon, which, by passing outward as well 
as forward, strengthens the transverse arch of the foot. The dorsal and plantar 
ligaments are continuous on the inner aspect of the internal cuneiform bone. 
The Cubo-cuneiform Articulation.—Transverse fibres unite the dorsal, plantar, 
and contiguous surfaces of the cuboid and external cuneiform bones, forming the 
dorsal, plantar and interosseous ligaments. 
Intercuneiform Articulations.—The three cuneiform bones are similarly con- 
nected by transverse dorsal and strong interosseous ligaments. On the plantar 
surface there is a strong band passing outward and forward from the inner to the 
middle cuneiform bone, but the tibialis posterior tendon serves for the plantar 
ligaments. 
Synovial Membrane.—A single synovial cavity is common to the scapho- 
cuneiform and the intercuneiform joints, and usually to the cubo-cuneiform joint, 
though the latter may have a separate synovial cavity. The synovial cavity 
between the cuneiform bones usually extends between the internal and middle 
cuneiform, to become continuous with that of the tarso-metatarsal joints between 
the middle and external cuneiforms behind and the second and third metatarsals 
in front. 
The movements in the above arthrodial joints, between the tarsal bones in THE TARSAL JOINTS. 
243 
front of the medio-tarsal joint, are limited to a slight gliding, due to the weight 
of the body rather than to muscular action, whereby the transverse arch of the 
foot is either flattened or deepened, thus increasing the elasticity and pliancy of 
the tarsus. 
6. Tarso-metatarsal and Intermetatarsal Articulations. 
The front surfaces of the three cuneiform bones and of the cuboid articulate 
with the proximal facets of the five metatarsals along a line (Hey’s line) made 
irregular by the forward projection of the internal and external cuneiform bones. 
The first, second, and third metatarsals articulate with the internal middle and 
external cuneiform bones respectively, the fourth and fifth with the cuboid. The 
second metatarsal is wedged in between the internal and external cuneiforms, and 
the fourth usually articulates with the external cuneiform laterally. The surfaces 
are held together by dorsal, plantar, and interosseous ligaments. The dorsal 
ligaments are flat, thin bands which pass forward from the tarsal to the metatarsal 
bones. The first metatarsal bone receives one from the internal cuneiform ; the 
ASTRAGALUS 
FLEXOR 
CHANNELS 
TIBIALIS . 
POSTERIOR 
ERONEUS 
LONGUS 
SCAPHO-CUNEI- 
- LIGAMENT 
•ERONEUS 
BREVIS 
Tl BIA LI S 
ANTERIOR 
Fig. 259.—The plantar ligaments. (Testut.) 
second, one from each cuneiform; the third, one from the external cuneiform ; 
the fourth, one from the external cuneiform and one from the cuboid; 
the fifth, one from the cuboid. The 'plantar ligaments are more irregular, and are 
strengthened by the expansions of the tibialis posterior and peroneus longus ten- 
dons and the long plantar ligament, A strong plantar band connects the internal 
cuneiform with the first metatarsal, and another with the second and third meta- 
tarsal bones. Other slender plantar bands connect the metatarsal with their 
corresponding tarsal bones. 
The interosseous ligaments, three in number, divide the synovial cavities of the 
tarso-metatarsal and intermetatarsal joints into three distinct parts, and offer 
resistance to disarticulation at this joint: (1) A strong interosseous ligament 
passes from the outer surface of the internal cuneiform to the contiguous non- 
articular portion of the inner surface of the second metatarsal, and shuts off the 
synovial cavity of the first tarso-metatarsal joint from that of the second and 244 
THE ARTICULATIONS. 
third, which also extends between the bases of the second and third and between 
the third and fourth metatarsal bones, and is continuous with that of the naviculo- 
cuneiform joints, etc. (2) Another interosseous ligament separates the last- 
described synovial cavity from that between the fourth and fifth metatarsals and 
between them and the cuboid, by passing from the antero-external edge of the 
external cuneiform to the inner surface of the fourth and the opposed non- 
articular surfaces of the third and fourth metatarsal bones. (3) A slender inter- 
osseous ligament often passes from the inner and front edge of the external cunei- 
form to the outer side of the second metatarsal bone. 
Intermetatarsal Articulations.—Proximal.—The four outer bones articulate with 
one another laterally, and are firmly bound together by short transverse dorsal, 
plantar, and interosseous ligaments. The interosseous ligaments connect the rough 
parts of the lateral surfaces in front of the articular facets, and are very strong. 
The dorsal ligament between the internal cuneiform and the second metatarsal 
takes the place of one between the first and second metatarsal bones, between 
which there is often a bursa with a facet on the first metatarsal only. Distal.— 
The digital extremities are loosely connected on their plantar aspect by four 
transverse bands blending with the plantar sesamoid plates. These form the 
transverse metatarsal ligament, which differs from the similar structure in the hand 
in having a band between the first and second metatarsal bones. 
Movements.—In the tarso-ra eta tarsal joints there are slight flexion and exten- 
sion, combined in the first, fourth, and fifth joints with ab- and adduction, which 
are most free in the fifth joint. In the tarso-metatarsal and intermetatarsal 
joints there are also gliding movements, whereby the arch is altered and the foot 
adapted to the ground and made more elastic and flexible. 
7. Metatarso-phalangeal and Interphalangeal Articulations. 
The rounded heads of the metatarsal bones and the concave bases of the first 
phalanges form articulations similar to the corresponding joints of the hand. 
They are connected by lateral ligaments and a thick fibrous plantar sesamoid plate, 
ossified laterally in the great toe-joint into two sesamoid hones, which attach the 
flexor brevis tendons and bound a groove for the long flexor tendon. 
The phalanges articulate with one another in the same manner as in the hand, 
and Avith the same ligaments {i. e., lateral and an inferior or glenoid ligament), 
except that the second and third phalanges are often ossified together in the foot. 
The dorsal ligaments of the above joints are principally formed by the extensor 
tendons. Each joint has a separate synovial membrane. 
The movements also are similar to those in the hand, except that at the meta- 
tarso-phalangeal joints extension is more free than in the hand; lateral motions 
(adduction and abduction) are less free, and take place to and from the second toe 
as a centre; and the movements of the great toe are much more limited than 
those of the thumb. 
Mechanism.—In walking the heel is the first part of the foot to touch the 
ground, and the weight of the body is transmitted to it through the posterior 
calcaneo-astragaloid joint, the foot being slightly adducted. As the other foot 
swings forward the outer border of the supporting foot is raised from the ground 
and the weight is transmitted to the inner toes; the foot becomes abducted, and 
leaves the ground by means of flexion of the great toe. In standing, the longi- 
tudinal arch is supported and the weight of the body borne by the plantar and 
calcaneo-navicular ligaments. The oblique direction of the expansion of the 
tibialis posterior and peroneus longus tendons, forward and outward and forward 
and inward respectively, help to support the longitudinal as well as the transverse 
arch of the foot. The latter is also supported by the transverse plantar and 
interosseous ligaments. The heads of the metatarsal bones, on which, and not on 
the toes, the foot rests in front, are somewhat spread out by the weight of the 
body, when the foot is raised on the toes. THE MUSCLES. 
F. H. GERRISH. 
A muscle is an organ whose essential part is a mass of striated muscular tissue, 
prolonged at its opposite ends or margins by cords, bands, or sheets of white 
fibrous tissue, which are fastened to other structures, usually bones. The mus- 
cular tissue is contractile, and is the active portion of the organ; the fibrous is 
strong and flexible, but is only passive. The contractile portion is called the 
muscle proper, the belly, or the body of the muscle; the fibrous extensions are 
called tendons (sinews), and sometimes, when greatly expanded, aponeuroses. The 
muscle proper may be compared to an engine, in which force is generated ; its 
tendons to the ropes by which the power is applied to distant objects. 
The relation of the tendons to the body of the muscle varies greatly in differ- 
ent muscles, both as regards their proportion and their arrangement. The belly 
may have tendinous structure only at its extremities, or one or both of the ten- 
dons may start far back upon the surface of the contractile mass, or a tendon 
may be in large part concealed in the midst of the muscular tissue. Several 
plates of tendon may be thus embedded, all connected with the terminal cord. 
When the tendons are found only at the ends of a muscle, the fibres of the two 
kinds of tissue are substantially in the same axis; but, when one of the other 
arrangements obtains, the muscular fibres are placed at an angle to the tendinous, 
as the barbs of a feather are related to the quill. 
In a few muscles there is a third tendon midway of its contractile mass, which 
is thus divided into two, becoming double-bellied—in technical phrase, digastric 
or biventral. One or more narrow, fibrous interruptions, partial or complete, 
may occur in some long muscles, constituting tendinous inscriptions. 
Bones in Tendons.—Small osseous masses, called sesamoid (“ like sesame ”) 
bones, are sometimes developed in tendons at points where they play over joints 
and are exposed to great pressure. Some of these are constant, as the patella, 
which is a sesamoid bone in the great muscle which straightens the leg on the 
thigh. 
Synovial Sheaths of Tendons.—Synovial membrane of the vaginal form is 
developed around many tendons which run in canals, as in the case of various 
digital muscles. Bursal synovial membranes are found at very many spots where 
tendons press upon one another or upon other organs, especially where they pass 
over prominences of bone. An articular synovial membrane may be prolonged 
beyond its joint, and furnish a lubricating sheath to the tendon of a neighboring 
muscle. 
Attachments of Tendons.—A tendon may be long or short; it may resemble 
a cord, a ribbon, or a sheet. In the last case it is commonly called an aponeurosis 
an undesirable, because etymologically misleading, name, but now firmly fixed 
by eminent sanction. Tendons are usually fastened to bones and cartilages, but 
may be attached to ligaments, skin, and other soft parts. The fibrous tissue of 
the tendon intermingles, and becomes continuous, with the periosteum of the bone, 
the perichondrium of the cartilage, or the deep layer of the skin, thus blending 
with a structure which is histologically identical with itself. When one con- 
245 246 
THE MUSCLES. 
siders the intimacy of relation between periosteum and bone, he is not sur- 
prised at the infrequency of the separation of a tendon from its osseous 
attachment. 
Proportionate Increase of Tendons with Age.—The tendinous portion of a 
muscle increases with years, and on this account the muscles of an adult are stitfer 
than those of a child, and the range of joint-movement is diminished. A child’s 
extended lower limb may be kept at a right angle with his trunk for a long time 
without causing him any discomfort; but the same procedure cannot be prac- 
tised upon an adult without producing great suffering and perhaps injury. 
The difference is due to the normal muscular extensibility in the infant on 
the one hand, and the equally normal tendinous inextensibility in the adult 
on the other. 
Origin and Insertion of Muscles.—A muscle is attached to two objects, and by 
its contraction lessens the distance between them. The part which is fastened to 
the more fixed of these objects is called the origin, the other the insertion. The 
origin is generally, especially in the limbs, proximal, the insertion distal. But 
the terms are entirely physiological and largely conventional, for in case of many 
muscles there is room for difference of opinion as to which portion is the more 
entitled to be called origin—the action being as frequently from one end as from 
the other. 
Fasciae.—The muscles in a region are maintained in close relations with each 
other by strong sheets of white fibrous tissue, which are wrapped firmly around 
them and often send shelves between them. These fibrous expansions are called 
fasciae (“bandages ”), and also aponeuroses of investment. They will be described 
in detail after the muscles have been considered. It will suffice here to remark 
that it is common for muscles to have extensive attachments, either of origin or 
insertion, to the fasciae which enwrap them. 
Ligamentous Action of Muscles.—The muscles perform a valuable service in 
keeping the cartilaginous surfaces of the movable joints in contact. The liga- 
ments proper are in many cases utterly inadequate for this work, as witness the 
joint between the shoulder and arm : remove the muscles and the humerus drops 
away from the glenoid fossa. But the muscles, which normally are never fully 
relaxed, keep up a tireless pressure, and, excepting violent accidents, never allow 
a separation to occur. This unvarying normal tension of muscular tissue is an 
obstacle to the reduction of fractures and dislocations ; for as soon as a bone is 
thrown out of its position, or a breach in the continuity of its substance occurs, 
the neighboring muscles, in demonstration of their being constantly somewhat 
tense, pull the luxated bone still further out of place, or cause the fragments to 
overlap each other. The muscular force is often so great as to require much 
strength, or anaesthesia, or both, to overcome it. 
The Mechanics of Muscular Attachments.—The points of attachment of most 
muscles are such as to place these organs at a great mechanical disadvantage. 
This is very evident in a large part of the muscles of the limbs. Take, for 
example, a muscle which bends the forearm upon the arm. It is attached to the 
lower half of the front of the humerus, crosses the elbow-joint, and just below 
this is attached to the ulna (Fig. 260). The loss of power involved here is illus- 
trated in a homely way by comparing the effort required to close a door by pulling 
it toward one, when it is grasped at a point near the hinges, with that which 
suffices when it is seized near its free edge, where the knob is usually placed. 
Manifestly the latter method is vastly easier. If the same plan were adopted in 
the flexion of the forearm, the muscle would be attached high on the humerus 
and low on the ulna (Fig. 261). But, although this would be advantageous as 
regards the expenditure of force, it would be strikingly otherwise in directions of 
quite as much importance. In the first place, the contraction of muscular tissue 
shortens it to one-half its length and no more, on which account the forearm 
could be bent upon the arm only to B, instead of to a much higher point, C, 
which is normally reached. In the second place, there would be a loss of rapidity PRIMARY.; SECONDARY, DIRECT, AND REVERSED ACTIONS. 
247 
Of movement of the lower end of the limb about proportionate to the gain of 
power; for the nearer to the hinge the force is applied, the more rapid will be the 
movement of the long arm of the lever. Then, the occupation by the muscle of 
each successive portion of the great triangular space included by it and the two 
bones when in flexion would be an intolerable interference with the usefulness of 
the limb, practically reducing the carrying power of the front of the forearm to 
Fig. 260.--Diagram showing the mechanical 
disadvantage of the points of attachment of 
many muscles. (F. H. G.) 
Fig. 261.—Diagram showing the effect of attaching a 
limb-muscle at points of the greatest mechanical advan- 
tage. (P. H. G.) 
nothing. There would also be a loss of a great deal of the important liga- 
mentous work of the muscles by their removal from close contact with the joints 
during their most pronounced activity. Thus it will be seen that the condition 
which exists, while extremely costly in the matter of muscular expenditure, is 
attended with advantages which are more than compensatory. 
Change in Direction of Muscular Force.—Tendons are often made to pass 
around prominences and through loops, the force originating in the muscle, thus 
experiencing a change of direction, as in the case of a rope which runs from an 
engine through a pulley to an object which is to be hoisted. The contractile force 
of such a muscle is applied in line with the portion of its tendon lying between 
the last angle which it makes and the point of its attachment to the object to be 
moved. On account of the lubrication of the tendon by synovia, which is always 
present in such cases, no appreciable loss of power is experienced by the change 
of direction. 
Primary, Secondary, Direct, and Reversed Actions.—A muscle which crosses 248 
THE MUSCLES. 
only one joint has but two possibilities of action: one, which may be called its 
direct action, is from a fixed origin to a movable insertion ; the other, its reversed 
action, is from a fixed insertion to a movable origin. 
But many muscles cross two or more joints, and by 
so much is the number of their movements aug- 
mented. For instance, the superficial flexor of the 
fingers primarily and directly flexes the second phal- 
anges upon the first phalanges (Fig. 262, A) ; but, 
when this movement is completed or is prevented, 
continuance of the contraction causes flexion of the 
first phalanges upon the metacarpal bones, and this 
may be called the direct secondary action (Fig. 262 
B). When this movement is accomplished or ar- 
rested, still further contraction produces flexion of 
the whole hand upon the forearm—the direct tertiary 
action (Fig. 262, C); and, finally, by persistence in 
the performance, the forearm is flexed slightly upon 
the arm—the direct quaternary action (Fig. 262, D). 
The reversed actions in these various stages are too 
obvious to require description. 
The segment of a limb on which a muscle acts 
carries with it, of course, all of the parts distal to it; 
and the movement effected by the contraction of the 
muscles is more manifest upon those parts than upon 
the segment bearing them, since they describe larger 
arcs. This is particularly noticeable in the prona- 
tion and supination of the radius. The change in the 
relation of the lateral parts of the forearm is far 
less apparent than the alteration in the attitude of 
the hand, which passively accompanies the radius. 
The Blending of Muscles.—Muscles are often asso- 
ciated in groups so intimately that, either at origin 
or insertion, there is an actual blending of substance. 
Myologists have not agreed upon an absolute rule 
for the settlement of the question of division or uni- 
fication in these cases, some describing as two or three distinct muscles what 
others regard as a compound one. There is much in this connection which is 
conventional and arbitrary, and, consequently, perplexing. 
The Muscles in Pairs.—Almost all of the skeletal muscles are arranged in 
pairs, and thus a description of one on either side will answer for its mate on the 
opposite side. A few are single and located about the median line, and in these 
there is generally a bilateral symmetry. 
The Size of Muscles varies from a fraction of an inch to many inches. In 
form they are extremely diverse,’and only in a small proportion is their resem- 
blance to familiar objects sufficiently striking to justify the application of names 
intended to be descriptive of their shape. 
Fig. 262.—Diagram showing the 
primary, secondary, tertiary, etc. 
actions of a muscle. (F. H. G.) 
The Nomenclature of Muscles. 
Latinity of Names.—The muscles are almost always called by their Latin 
names. A few have become Anglicized, commonly by the omission of the ter- 
mination (as deltoid, instead of deltoideus); but the attempts which have been 
made to displace the Latin appellations by substituting English translations of 
them have always failed. The student, however, should learn the exact meaning 
of every name, as this knowledge cannot fail to be of great assistance to him. 
For example, almost one-half of the names of the muscles moving the several NAMES OF MOVEMENTS PRODUCED. 
249 
segments of the upper limb, are descriptive of the action of these muscles, and 
nearly two-thirds of these convey some additional information—of form, situa- 
tion, or size. The majority of the names of the other half of this group indicate 
position, and the residue call attention to some characteristic of shape or resem- 
blance. From this it will be seen that the names are not arbitrary, but are 
designed to be descriptive, and, consequently, are helpful in the first learning and 
m the permanent retention of the facts. 
The Latin word musculus (“muscle”) is always implied in the name of a 
muscle, and the part which is expressed is either an adjective or a noun in appo- 
sition, with or without limiting words. 
Reasons for the Names of Muscles.—Muscles are named from various con- 
siderations, and occasionally more than one of these is appealed to in the 
selection of a name. It is noticeable that the names of individuals are not 
used in the nomenclature of muscles, as they are in almost every other branch 
of anatomy. 
The following are the principal derivations of the names of muscles : 1, action 
or supposed action, as levator scapulae, “ the lifter of the shoulder-blade,” supi- 
nator, “ the muscle producing supination ”—turning the part onto its back ; 2, 
form, as gracilis, “ the slender muscle,” serratus, “ the saw-toothed muscle ; ” 3, 
the form of two muscles symmetrically located on opposite sides of the body, as 
trapezius, “ the table-like muscle,” though each trapezius is not trapezoid but 
triangular ; 4, resemblance to a natural object, as lumbricalis, “ the earthworm 
muscle,” solens, “ the sole-fish muscle ; ” 5, situation, as frontalis, “ the forehead 
muscle,” subclavins, “ the muscle under the collar-bone ;” 6, attachments, as coraco- 
brachialis, “ the muscle connecting the coracoid process and the arm,” brachio- 
radialis, “ the muscle connecting the arm and the radius ; ” 7, size, either absolute, 
a§ vastus, “ the great muscle,” or comparative, as latissimus, “ the broadest mus- 
cle;” 8, division, as quadriceps, “the four-headed muscle,” multifidus, “the 
muscle of many clefts;” 9, paired condition, as gemellus, “the twin muscle;” 
10, supposed singleness, as azygos uvulae, “ the uvula muscle not yoked to a mate ; ” 
11, involvement of structure, as complexus, “ the complicated muscle ; ” 12, direction 
°f fibres, as rectus, “ the straight muscle,” transversal is, “ the transverse muscle ; ” 
13, relative proportion of contractile and non-contractile tissues, as semimembranosus, 
“the half-membrane muscle,” semitendinosus, “the half-tendon muscle;” 14, 
existence of a tendon midway between two contractile portions, as digastric and 
biventer, “the muscles with two bellies;” 15, occupation in which the muscle 
18 thought to be useful, as sartorius, “ the tailor’s muscle,” buccinator, “ the 
trumpeter’s muscle;” 16, expression produced, as risorius, “the laughing mus- 
cle ;” 17, the subordinate character of the ivorlc done, as accessorius, “the assistant 
muscle.” 
Names of Movements Produced.—Most of the movements of the parts upon 
which muscles act have received specific names, some of which are applied also to 
the attitudes resulting from these movements. When one part is bent upon 
another, the movement is called flexion (“ a bending ”) ; when the part is 
straightened out, the action is extension (“ a stretching ”); and thus flexion and 
extension are antagonistic actions and attitudes. The moving of a part further 
away from the middle line (the median plane of the whole body being meant, 
unless otherwise specified) is abduction (“ a drawing from ”); the opposite move- 
ment, by which the part is restored to its former position, is adduction (“ a draw- 
ing to ”). The slight difference between these antipodal words should be noted 
~the one begins with ah, the Latin for “ from,” the other with ad, the Latin for 
to. When a part is made to revolve upon its long axis, the movement is rota- 
tion, (“a revolving”); and when its lower extremity is caused to describe a 
circle, and the part itself thus traverses the periphery of a cone, the action is cir- 
cumduction (“ a drawing around ”). The movement which turns a part onto its 
lace is pronation (“ a bending forward ”), and the reverse is supination (“ lying on 
the back”). 250 
THE MUSCLES. 
The Order of Study.—The muscles will be considered in the following order: 
The muscles of the upper limb. 
The muscles of the lower limb. 
The muscles of the trunk. 
(a) those of the back, including the dorsum of the neck. 
(if) those of the abdomen. 
(c) those of the thorax. 
The muscles of the neck, at the front and sides. 
The muscles of the head. 
The muscles of the tongue, pharynx, and soft palate will be presented in con- 
nection with the organs of digestion; those of the larynx with the respiratory 
system ; those of the eye and ear with special sense organs; and those of the 
perineum with the genitals. 
Illustrative Pictures are provided so liberally in this chapter, and show certain 
details so clearly, that it is practicable to omit from the verbal descriptions many 
things which are usually given in them, and this, too, not only without diminu- 
tion of clearness, but often with distinct advantage in this regard, since facts can 
usually be more quickly apprehended and more firmly held when presented by 
pictorial means, than when introduced into the mind through the medium of 
words. Thus, the form of a muscle, the most important relations of its contractile 
and tendinous portions, and its principal relations to neighboring muscles are 
generally shown so plainly in the drawings of dissections, that their description 
can safely and profitably be omitted from the text. 
The Outline Drawings of individual muscles show in each instance the location 
and proportionate size of the areas of osseous origin and insertion, and also the 
margins of the entire muscle from the selected point of view, thus suggesting its 
action. In cases where a surface of attachment or a part of the outline is not visible 
from the chosen point, the concealed portion is drawn in dots or broken line, and is 
represented as if the intervening skeletal structure were transparent. 
Minuteness of verbal description of muscular attachments, while morphologi- 
cally interesting, is of little or no practical value to the physician and surgeon, 
and, consequently, is not attempted. The essential facts are presented in the 
text, and in most cases are abundantly illustrated in the outline drawings. 
Connection with Neighboring Soft Parts.—The attachments to superjacent fas- 
ciae, intermuscular septa, and other soft parts will often be omitted from the text 
for the sake of brevity, especially when these are of insignificant extent, or have 
already been mentioned in connection with the group of muscles concerned. It 
may usually be assumed that a muscle has some attachment to the fibrous struct- 
ures—investing sheets, partitions between it and its immediate neighbors, liga- 
ments, etc.—with which it is in close contact. 
The Action assigned to a muscle is that effected by its contraction from a fixed 
origin to a movable insertion—the direct primary action—unless otherwise speci- 
fied. The direct secondary and all reversed actions can be worked out correctly 
and easily by one who has learned the direct primary action and the anatomical 
reasons for it. 
Classification of the Limb Muscles.—The classification of the muscles of the 
limbs which is here given is physiological, being based upon their primary and 
most characteristic action. Although this grouping is very different from that 
which is generally followed, it is believed to be more useful as an aid in learning 
the facts of greatest importance in myology, and in applying the knowledge thus 
gained in medical and surgical practice. Of course, it is not claimed that this 
classification is perfect—none which rests upon a physiological basis can be ; but 
long employment of it has demonstrated its utility in attracting and holding 
the interest of the student, and this mainly because there is kept constantly 
in view the application of the facts which he is learning. After the muscles 
of a limb have been described, their classification on a regional basis will be 
presented. THE MUSCLES OF THE UPPER LIMB. 
251 
THE MUSCLES OF THE UPPER LIMB. 
Each of the four primary segments of the upper limb is capable of a wide 
range of action. 
Movements of the Shoulder,—ln the chapter on the joints the scapula is shown 
to be somewhat movable upon the clavicle ; but, in studying the principal action 
of the muscles, the movements of the claviculo-acromial joint may be ignored with- 
out serious departure from the fact, and the skeleton of the shoulder may be 
regarded as practically a single bone. This framework is pivoted upon the trunk 
at the sterno-clavicular articulation, and is proximally attached at other points by 
muscles only. The movements of the shoulder, therefore, centre on the upper 
end of the sternum, and are made upward, downward, forward, and backward, the 
terms used to designate them—elevation, depression, etc.—requiring no explanation. 
Movements of the Arm.—The arm, being united to the shoulder by means of 
a ball-and-socket joint, can be moved in every direction which is consistent with 
the integrity of the articular structures and with the retention of the humeral 
head in the glenoid fossa. Its movement forward is flexion, backward is exten- 
sion, outward is abduction, inward is adduction. When it is rolled on its own 
axis so that its front turns toward the trunk, the movement is inward rotation ; 
when it revolves so as to turn its front away from the trunk, the action is external 
rotation. Its circumduction is inward when the front semicircle described by the 
lower end of the arm is made from the outside toward the mid-line, and the oppo- 
site movement is outward, circumduction. 
Movements of the Forearm.—The elbow-joint proper is a hinge, allowing 
motion between the forearm and arm only forward, which is flexion, and backward, 
which is extension. Between the two forearm bones, however, are movements which 
consist in the overlapping of the ulna by the radius, pronation, and the opposite 
action by which the parts are restored to their anatomical attitude, supination. 
Movements of the Hand.—The articulation between the forearm and carpus 
permits motion of the hand forward, which is flexion, backward which is exten- 
sion, sidewise toward the mid-line, adduction, and from this line, abduction. Cir- 
cumduction, which is accomplished by a combination of these movements, is 
inward or outward, according to the rule given above. In these various move- 
ments of the whole hand some motion takes place in the joints between the car- 
pal bones ; but these are so slight as to be practically inappreciable, and require 
no further mention. 
Movements of the Metacarpal Bones.—The second, third, and fourth metacarpal 
bones are so firmly joined to the carpus that but little motion is possible, even 
when their respective digits are most forcibly acted upon. The fifth metacarpal 
bone has an appreciable forward movement, which is flexion, a backward, which 
is extension, and slight lateral motions, abduction and adduction. The first meta- 
carpal is so articulated at the wrist that its range is very great, and this freedom 
of action is more than a compensation for the deficiency of a phalanx in its digit. 
Movements of the Common Digits.—Forward movement of the fingers and of 
each of their phalanges is flexion, and backward movement is extension. The lateral 
movements of the fingers are called abduction and adduction ; but the median line 
ol the body is not here taken as the plane from and to which the action is reckoned, 
a line drawn through the middle of the middle finger when it is in repose being 
substituted. There is practically no lateral motion at the interphalangeal joints. 
Movements of the Thumb.—It is to be particularly noticed that the first 
metacarpal is so placed that the thumb is in advance of the plane of the other 
digits and its palmar aspect is about at a right angle with theirs. Consequently, 
a bending at the joints of the thumb toward its palmar aspect, which is flexion, 
as in the case of the other digits, causes it to cross the palm of the hand toward 
the hypothenar eminence. The restoring movement is extension. Abduction of 
Movements of the Upper Limb. 252 
THE MUSCLES. 
the thumb is in the direction of flexion of the fingers, and its adduction is in the 
direction of their extension. Its circumduction requires no especial description. 
It will be observed that, from the shoulder-joint down, the forward movements 
are flexions, and the backward movements are extensions—the thumb offering the 
only exceptions. In the lower limb this rule does not apply. 
Classification of the Muscles of the Upper Limb on the Basis of 
their Principal Action. 
Upward and backward. 
Moving the Shoulder. 
Downward and forward. 
Trapezius. 
Levator scapulae. 
Bhomboideus minor. 
Rhomboideus major. 
Serratus magnus. 
Pectoralis minor. 
Subclavius. 
Moving the Arm. 
Abductors. 
Pectoralis major. 
Coraco-brachialis. 
Adductors. 
Deltoideus. 
Supraspinatus. 
also flexors. 
Latissimus. 
Teres major. 
also extensors. 
Outward Rotators. 
Inward Rotator. 
Infraspinatus. 
Teres minor. 
Subscapularis. 
Moving the Whole Forearm. 
Biceps flexor cubiti. 
Brachialis. 
Brachio-radialis. 
Flexors. 
Triceps extensor cubiti. 
Anconeus. 
Extensors. 
Moving the Outer Part of the Forearm. 
Pronator teres. 
Pronators. 
Supinator. 
Supinator. 
Pronator qnadratus. 
Flexors. 
Moving the Whole Hand 
Extensors. 
Flexor carpi radialis. 
[Flexor] palmaris longus, 
Flexor carpi ulnaris. 
Extensor carpi radialis longus. 
Extensor carpi radialis brevis. 
Extensor carpi ulnaris. 
Moving the Fingers 
Flexors. 
and the Fifth Metacarpal Bone. 
Extensors. 
Flexor sublimis digitorum. 
Flexor profundus digitorum. 
*Flexor ossis metacarpi minimi digiti. 
*Flexor brevis minimi digiti. 
*Lumbricales. 
Extensor communis digitorum. 
Extensor minimi digit!. 
Extensor indicis. 
*lnterossei dorsales. 
Abductors. 
*lnterossei palmares. 
Adductors. 
*Abductor minimi digiti. 
Moving the Thumb 
and its Metacarpal Bone. 
* Flexor ossis metacarpi pollicis. 
* Flexor brevis pollicis. 
Flexor longus pollicis. 
Flexors. 
Extensor ossis metacarpi pollicis. 
Extensor brevis pollicis. 
Extensor longus pollicis. 
Extensors. MUSCLES MOVING THE SHOULDER. 
253 
Abductor. 
Adductor. 
* Abductor pollicis. 
* Situated entirely in the hand. 
* Adductor pollicis. 
MUSCLES MOVING THE SHOULDER. 
Trapezius. 
Levator scapulae, 
Rhomboideus minor. 
Rhomboideus major. 
Upward and backward. 
Downward and foncard. 
Serratus magnus. 
Pectoralis minor. 
Subclavius. 
All of these muscles arise from the trunk, excepting one, which has its origin 
in the neck. All are inserted into the skeleton of the shoulder. 
Trapezius (Figs. 263, 264).—So called from the resemblance which it with its 
mate bears to a four-sided table (Greek trapeza, “ a table ”). Synonym, cucullaris, 
LAST CERVI- . 
CAL VERTEBRA 
LAST THORA- 
CIC VERTEBRA" 
LAST LUM- 
BAR VERTEBRA 
Fig. 263.—Muscles in the superficial layer of the hack. (Testut.) 
from the likeness of the pair to a monk’s hood (Latin cucullus). Situation, super- 
ficial, on the dorsal aspect from the occiput to the base of the thorax, and lat- 254 
THE MUSCLES. 
erally to the peak of the shoulder; also, at the side of the neck, and the top 
and front of the shoulder. Origin, the inner third of the superior curved line 
and the protuberance of the occipital bone, the ligamentum nuchse, the spines 
of the last cervical and all of the thoracic vertebrae, and their supraspinous 
ligament. Direction of fibres, convergent: the upper, down-, out-, and forward ; 
the middle, outward ; the lower, up- and outward. Insertion, the outer third of 
the hind border of the clavicle, the inner border of the acromion, the upper bor- 
der of the scapular spine, the tubercle near its inner end. Action : the upper 
Fig. 264.—Trapezius of right side : outline and 
attachment-areas. (F. H. G.) 
Fig. 265.—Muscles in the second layer of the hack 
and on the dorsum of the shoulder. (Testut.) 
part raises the shoulder, the middle draws the shoulder toward the spine, the 
lower pulls the scapula down- and inward, and tilts the acromion upward. All 
together lift the shoulder and rotate the lower angle of the scapula outward. 
Nerves, the spinal accessory, and the third and fourth cervical. 
Levator Scapulae (Figs. 265, 266).—“ The lifter of the scapula.” Synonym, 
levator anguli scapulae, “ the lifter of the angle of the scapula,” Situation, on the 
side of the neck from the vertebrae to the upper scapular angle. Origin, the hind RHOMB OIDE US MAJOR. 
255 
tubercles of the transverse processes of the upper four or five cervical vertebrae. 
Direction, down-, out-, and backward. Insertion, the vertebral border of the 
scapula from the upper angle to the root of the spine. Action : it lifts the upper 
angle of the scapula and depresses the tip of the shoulder. Nerves, the third, 
fourth, and fifth cervical. 
Shomboideus Minor (Figs. 265, 267).—“ The smaller rhomb-shaped muscle.” 
Situation, in the back, between the spinal column and the scapula. Origin, the 
ontl wS'n26?' levator scapulae of right side, rear view 
outline and attachment-areas. (F. H. G.) 
Fig. 267.—Rhomboideus minor and rhomboideus 
major of right side: outline and attachment-areas. 
(F. 11. G.) 
ower part of the nape ligament, the spines of the seventh cervical and first 
loracic vertebrae. Direction, down- and outward. Insertion, the vertebral bor- 
*ei the scapula at the root of its spine. Action :it draws the scapula up- 
and inward, and depresses the tip of the shoulder by rotating the scapula. Nerve, 
10 hfth cervical. This muscle is often united with the following : 
Rhomboideus Major (Figs. 265, 267).—u The larger rhomb-shaped muscle.” 
nation, in the back, between the spinal column and the scapula. Origin, the 
T-puious processes of the upper four or five thoracic vertebrae and the correspond- 
Jug supraspinous ligament. Direction, down- and outward. Insertion, the ver- 256 
THE MUSCLES. 
tebral border of the scapula, between the root of the spine and the lower angle. 
Action : it draws the scapula up- and inward. Nerve, the fifth cervical. 
Serratus Magnus (Fig. 268).—“ The great saw-toothed muscle.” Synonym, 
serratus anterior. Situation, on the upper two-thirds of the side of the chest. 
Origin, by digitations from the outer surface of the upper eight or nine ribs, 
Fig. 268.—Serratus magnus of right side. The scapula has been turned backward and drawn outward, 
(Modified from Testut.) 
several inches from their front ends. Direction, up- and backward. Insertion, 
the front of the vertebral border of the scapula, and the surfaces at the upper 
and lower angles. The first digitation, which comes from the second, as well as 
from the first rib, runs to the surface at the upper angle; the second and third 
digitations connect the corresponding ribs with the vertebral border from near 
the upper to near the lower angle ; the rest of the slips converge to the surface 
at the lower angle. Action : it draws the shoulder forward, as in pushing; the 
lower segment rotates the apex of the scapula upward. Nerve, the posterior 
thoracic. The lower five points of origin interlock with similar slips of the 
obliquus externus abdominis. 
Pectoralis Minor (Fig. 269, 270).—“ The smaller breast-muscle.” Situation, 
in the front of the chest. Origin, the outer surfaces of the third, fourth, and fifth 
ribs, near their cartilages. Direction, up- and outward. Insertion, the coracoid 
process of the scapula. Action: it draws the shoulder down- and forward. 
Nerve, the internal anterior thoracic. SUB CL A VIUS. 
257 
Subclavius (Fig. 269).—“ The under-the-clavicle muscle.” Situation, indi- 
Fig. 269.—Pectoralis minor of right side. (Testut.) 
cated by its name. Origin, the first rib and its cartilage, at their junction. Direc- 
tion, out- and upward. Insertion, the groove in the under surface of the clavicle. 
Fig. 270.—Pectoralis minor of right side ; outline and attachment-areas. (F. H. G.) 
Action: it draws the shoulder down- and forward. Nerve, from the fifth and 
sixth cervical. 258 
THE MUSCLES. 
MUSCLES MOVING THE ARM. 
Deltoideus. 
Abductors. 
Pectoralis maior. 1 , n 
i i• 1 • )■ also flexors. 
Coraco-bracnialis. J 
Latissimus. 1 , , 
rp . > also extensors. 
ieres major, j 
Adductors. 
Supraspinatus 
Outward Rotators. 
Inward Rotator. 
Infraspinatus. 
Teres minor. 
Subscapularis. 
The largest two of these muscles arise mostly from the trunk, and in some 
part from the shoulder ; but the majority arise wholly from the shoulder. All 
of them are inserted into the humerus in its upper half. 
Deltoideus (Figs. 271,272, 289),—“The delta-like muscle”—“delta” being 
the name of a Greek letter of triangular shape. It is commonly Anglicized into 
“ deltoid.” Situation, between the most prominent parts of the shoulder and the 
Fig. 271.—Front of chest and shoulder of right side, superficial muscles. (Testut.) 
middle of the outside of the arm. Origin, the front of the outer third of the 
clavicle, the outer border of the acromion, and the lower border of the spine of DEL TO IDE US. 
259 
the scapula—corresponding closely with the insertion of the trapezius. Direction, 
trom the clavicle and the scapular spine down- and outward, from the acromion 
Fig. 272.—Deltoideus of right side, viewed from above ; outline and attachment-areas. (F. H. G.) 
downward—all parts converging. Insertion, the deltoid eminence (or impression) 
of the humerus. Action : it abducts the arm, lifting it to the horizontal. The 
Fig. 273.—Supaspinatus of right side, viewed from above; outline and attachment-areas. (F. H. G.) 
clavicular portion acting alone draws the arm forward; that from the scapular 
spine by itself carries the arm backward. The arm, being raised as far as the 
deltoid can affect it, is elevated to the perpendicular by the trapezius, the two 
muscles being almost continuous in structure—practically one muscle with an 
osseous inscription. Nerve, the circumflex. 
Pig. 274.—Pectoralis major of right side: outline and attachment-areas. (F. H. G.) 260 
THE MUSCLES. 
Supraspinatus (Figs. 273, 278).—“The muscle above the spine” of the 
scapula. Situation, in the supraspinous fossa and above the head of the humerus. 
Origin, inner two-thirds of supraspinous fossa. Direction, outward beneath acro- 
mion. Insertion, uppermost facet of great tuberosity of humerus. Action, abduc- 
tion of the arm. Nerve, the suprascapular. 
Pectoralis Major (Figs. 271, 274).—“ The greater breast-muscle.” Situation, 
in the upper, anterior part of the chest, and in front of the axilla. Origin, the 
sternal half of the anterior surface of the clavicle, the anterior surface of the 
sternum (except the appendix), the cartilages of the upper six ribs. Direction : of 
LAST CERVI- _ 
CAL VERTEBRA 
LAST THORA- 
CIC VERTEBRA’ 
LAST LUM- _ 
BAR VERTEBRA 
Fig. 275. Coraco-brachialis of 
right side: outline and attachment- 
areas. (F. H. G.) 
Fig. 27G.—Muscles in the superficial layer of the back. (Testut.) 
the clavicular portion (which is separate at its origin) down- and outward ; of the 
central, outward; of the lower, out- and upward—all parts converging to one 
broad tendon, which twists on itself, the lower fibres passing behind and becoming 
uppermost. Insertion, the external bicipital ridge of the humerus. Action : it 
draws the arm inward and forward, and rotates it inward. Nerves, the internal 
and external anterior thoracic. 
Coraco-bracMalis (Figs. 275, 283, 285).—“ The coracoid (process)-arm mus- 
cle ”—the name being derived from the parts connected. Situation, in the inner TERES MINOR. 
261 
side of the upper half of the arm. Origin, the coracoid process of the scapula. 
Direction, downward and slightly outward. Insertion, the inner border of the 
humerus at the middle of the shaft. 
Action, adduction and flexion of 
the arm. Nerve, the musculo- 
cutaneous. 
Latissimus (Figs. 276, 277). 
“ The broadest muscle ”—from 
the Latin lotus, “ broad.” Syno- 
nym, latissimus dorsi, “ the broad- 
est of the back.” Situation, in 
the back, from the lower half of 
the spine to the upper part of the 
arm. Origin, the spines of six 
or seven lower thoracic vertebrae, 
and, through the lumbar fascia, 
the spines of the lumbar and sac- 
ral, and the back of the outer lip 
°f the iliac crest, the last three or 
four ribs, and often the lower 
angle of the scapula. Direction, 
upward, outward, and forward, 
converging to the insertion, the 
tendon twisting from above down- 
ward and backward, so that its 
front is continuous with the back 
of the muscle. Insertion, the 
floor of the bicipital groove. Ac- 
tion, adduction, extension, and 
rotation inward. Nerve, the long 
subscapular. The costal points 
of origin interlock with those of 
the obliquus externus abdominis. 
Teres Major (Figs. 278, 279).— 
“The greater round muscle.” 
Situation, between scapula and 
upper end of arm, in hind wall 
of armpit. Origin, the oval sur- 
face on the back of the scapula at 
its lower angle. Direction, up-, out-, 
and forward. Insertion, the inner 
bicipital ridge. Action, adduction, 
extension, and inward rotation of 
arm. Nerve, the lower subscapular. 
Infraspinatus (Figs. 278, 280). 
The muscle below the spine ” 
of the scapula. Situation, in the 
infraspinous fossa and behind the 
lead of the humerus. Origin, 
the inner two-thirds of the infra- 
spinous fossa. Direction, outward. 
Insertion, the middle facet of the 
great tuberosity of the humerus. 
Action, external rotation of the 
arm. Nerve, the suprascapular. 
Teres Minor (Figs. 278-281).—“ The smaller round muscle.” Situation, 
between the scapula and the upper end of the arm, in the hind wall of the arm- 
Fig. 277.—Latissimus of right side: outline and attach- 
ment-areas. (F. H. G.) 262 
THE M USCLES. 
Fig. 278.—Muscles of the dorsum of the scapula, right side. (Testut.) 
Fig. 279.—Teres major of right side; outline 
and attachment-areas. (F. H. G.) 
Fig. 280.—Infraspinatus of right side; outline and 
attachment-areas. (F. H. G.) 
Fig. 281.—Teres minor of right side: outline and 
attachment-areas. (F. H. G.) 
Figv 282.—Subscapularis of right side : outline and 
attachment-areas. (F. H. G.) MUSCLES MOVING THE WHOLE FOREARM. 
263 
pit. Origin, the dorsum of the scapula, along its axillary border. Direction, 
upward and outward. Insertion, the lowest facet on the great tuberosity of the 
humerus. Action, external rotation of the humerus. Nerve, the circumflex. 
Subscapularis (Figs. 282, 283).—“The muscle under the scapula”—though it 
is beneath the bone only when the body is prone. Situation, in front of the scapula 
and the head of the humerus. Origin, the greater part of the venter of the scapula. 
Direction, outward and forward. Insertion, the small tuberosity of the humerus. 
Action, inward rotation of the humerus. Nerves, the upper and lower subscapular. 
MUSCLES MOVING THE WHOLE FOREARM. 
Flexors. 
Extensors. 
Biceps flexor cubiti. 
Brachialis. 
Triceps extensor cubiti. 
Anconeus. 
Brachio-radialis. 
One of these muscles arises from the scapula, one from the scapula and 
humerus, and three from the humerus alone. All are inserted into the skeleton 
°f the forearm. 
Fig. 283.—Muscles of the front of the right shoulder 
and arm. (Testut.) 
Fig. 284.—Biceps flexor cubiti of right side 
outline and attachment-areas. (F. H. G.) 
Biceps Flexor Cubiti (Figs. 283, 284).—“ The two-headed flexor of the fore 264 
THE MUSCLES. 
arm.” Situation, in the front of the arm. Origin, the scapula—the long head: 
the upper border of the glenoid fossa; the short head : the coracoid process. 
Direction, the long head : over the caput humeri, through the shoulder-joint, in 
the bicipital groove, and down to the forearm ; the short head unites with the 
long about one-fourth way down the arm. Insertion, the main tendon to the 
hind part of the radial tuberosity; a secondary tendon (called also the semi- 
lunar or bicipital fascia) passes obliquely inward, and ends in the deep fascia of 
the forearm over the pronator teres. Action, flexion of forearm. If the hand 
is pronated, the biceps supinates it. The second tendon of insertion tightens 
the forearm fascia. Nerve, the musculo-cutaneous. The synovial membrane of 
the shoulder-joint is prolonged downward, and invests the tendon of the long 
head. 
Brachialis (Figs. 285, 286).—“The muscle of the arm.” Synonyms, brachi- 
alis anterior, brachialis anticus, “the front muscle of the arm.” Situation, in the 
Fig. 285.—Muscles of the right arm, front 
view, the biceps having been removed. (Testut.) 
Fig. 286.—Brachialis of right 
side: outline and attachment- 
areas. (F. H. G.) 
front of the arm. Origin, the lower half of the front of the humerus. Direc- 
tion, downward to the forearm. Insertion, the inner part of the coronoid proo TRICEPS EXTENSOR CUBITI. 
265 
ess of the ulna. Action, flexion of the forearm. Nerves, the musculo-cutane- 
ous and (slightly) the musculo-spiral. 
Brachio-radialis (Figs. 287, 288, 303).—“ The arm-radius muscle/’ from its 
attachments. Synonym, supinator longus, “ the long supinator.” Situation, the 
outer and front part of the lower fourth of the arm and of the whole forearm. 
Fig. 288.—Brachio-radialis 
of right side, outside view: 
outline and attachment-areas. 
(P. H. G.) 
Fig. 287.—Superficial muscles of front of right 
forearm. (Testut.) 
Origin, the upper two-thirds of the external condylar ridge of the humerus. 
Direction, downward. Insertion, the base of the styloid process of the radius. 
Action, mostly flexion of the forearm; but, when the hand is prone, this muscle is 
capable of nearly half-supinating it; after strong supination, the muscle will par- 
tially effect pronation. Nerve, the musculo-spiral. 
Triceps Extensor Cubiti (Figs. 289-291).—“ The three-headed extensor of the 
forearm.” Situation, in the back of the arm. Origin, the long (middle) head : 
below the glenoid fossa of the scapula on the neck and upper part of the axillary 
border; the external head : the hind surface of the humerus above the musculo- 
spiral groove; the internal (deep) head : the hind surface of the humerus below 266 
THE MUSCLES. 
the musculo-spiral groove. Direction, downward, all the heads uniting in a 
common tendon. Insertion, the tuberosity of the olecranon process of the ulna. 
Action, extension of forearm. Nerve, the musculo-spiral. 
Anconeus (Figs. 289, 292, 310).—“The elbow muscle.” Situation, at the 
back and outer side of the elbow-joint, mostly in the forearm. Origin, the hind 
SUPERIOR PROFUNDA 
MUSCULO-SPIRAL NERVEH 
Fig. 289.—Muscles on the dorsum of the right shoulder and arm 
(Testut.) 
Fig. 290.—Triceps extensor cuhiti of 
right side: part of the scapular head has 
been removed and shows in outline. 
(Testut.) 
part of the external condyle of the humerus. Direction, obliquely downward. 
Insertion, the outer side of the olecranon process, and the upper fourth of the 
back of the shaft of the ulna. Action, extension of forearm. Nerve, the musculo- 
spiral. The anconeus is a continuation of the triceps, and is sometimes described 
as the fourth head of the latter, thus converting it into a quadriceps, or four- 
headed muscle. 
MUSCLES MOVING THE OUTER PART OF THE FOREARM. 
Pronators. 
Supinator. 
Pronator teres. 
Pronator quadratus. 
Supinator. 
Of the pronators one arises from the humerus and ulna, the other from the 
ulna only. The supinator arises from the humerus and ulna. All are inserted PR ON A TOR QUA BRA TUS. 
267 
into the radius, which alone of the forearm bones is moved in pronation and 
supination. 
Pronator Teres (Figs. 287, 293).—“ The round pronator/’ Situation, in the 
front of the forearm. Origin, the superficial head : the inner condyle of the 
humerus and a small part of the ridge above it; the deep-head : the inner 
border of the coronoid process of the ulna. Direction, out- and downward. 
Insertion, the middle of the outer surface of the radius. Action, pronation 
Fig. 291.—Triceps extensor cubiti of right side: out- 
line and attachment-areas. (F. H. G.) 
Fig. 292.—Anconeus of right side: outline 
and attachment-areas. (F. H. G.) 
of the hand by moving the radius to which the hand is articulated ; also slight 
flexion of the forearm. Nerve, the median. 
Pronator Quadratus (Figs. 294, 318).—“ The square pronator.” Situation, in 
the lower quarter of the front of the forearm, close to the bones. Origin, the 268 
THE MUSCLES. 
inner part of the lower fourth of the front surface of the shaft of the ulna. 
Direction, outward. Insertion, the lower fourth of the front of the radius. Action, 
pronation of radius, and, consequently, of the hand. Nerve, anterior interosseous 
branch of the median. 
Fig. 293.—Pronator teres, right side: outline 
and attachment-areas. (F. H. G.) 
Fig. 294.—Pronator quadratus of right side 
outline and attachment-areas. (F. H. G.) 
Supinator (Fig. 295).—“ The supinator.” Synonym, supinator brevis, “ the 
short supinator.” Situation, deeply in the upper third of the outer part of the 
forearm. Origin, the external condyle of the humerus, the external lateral and 
orbicular ligaments, the triangular area below the small sigmoid cavity. Direc- 
tion, out- and downward, wrapping the upper part of the radius in a sling. Inser- 
tion, the back of the neck, and the hind and outer surfaces of the shaft of the 
radius above the oblique line. Action, supination. Nerve, the posterior inter- 
osseous division of the musculo-spiral. MUSCLES MOVING THE WHOLE HAND. 
269 
MUSCLES MOVING 
THE WHOLE HAND. 
Flexor carpi radialis. 
[Flexor] palmaris longus. 
Flexor carpi ulnaris. 
Flexors. 
Extensor carpi radialis longus. 
Extensor carpi radialis brevis. 
Extensor carpi ulnaris. 
Extensors. 
All arise from the humerus, and the flexor and extensor on the ulnar side 
come from the ulna also. The palmaris longus is inserted into the palmar fascia. 
All which have u carpi ” in their names are in- 
serted into metocarpal bones, and only one of them 
into any part of the carpus also. Their action, 
however, is correctly indicated by their names, 
the wrist, carrying the rest of the hand, being 
alternately flexed and extended. The second, 
third, and fourth metacarpal bones have prac- 
tically no motion on the carpus, and the first and 
fifth are moved by special muscles. The pal- 
maris longus, though primarily a tensor of the 
palmar fascia, secondarily is a flexor of the hand 
—-just as the tensor vaginae feraoris is first a 
tightener of the fascia lata, and then an abduc- 
tor of the thigh—and, therefore, a bracketed 
word implying this, and aiding the grouping by 
making a uniformity of name which corresponds 
with the practical identity of action, has been 
prefixed. The adduction of the hand is accom- 
plished by the simultaneous action of the flexor 
EXTERNAL 
CONDYLE 
OLECRA-... 
NON 
HEAD OF 
RADIUS 
ULNA 
Rflbius 
Fig. 295.—Supinator of right side. 
(Testut.) 
carpi ulnaris and the extensor carpi ulnans ; its abduction by the simnitaneons 
action of the flexor carpi radialis and the extensor carpi radialis longus. Observe 
that the external part of the lower end of the humerus gives origin to the exten- 
sors, the internal to the flexors. At their origin from the internal condyle and 
its neighborhood the flexors of the hand are so blended with the pronator teres 
and the flexor sublimis digitornra as to constitute one mass. On and about the 
external condyie is a similar association of extensors and supinator. 
Flexor Carpi Radialis (Figs. 296, 297).—'“ The flexor of the wrist on the 
radial side.” Situation, in the front of the forearm. Origin, the inner condyle 
of the humerus. Direction, downward and a little outward. Insertion, the base 
of the second metacarpal bone on its palmar aspect. Action, flexion and slight 
pronation of the hand. In conjunction with the extensor carpi radialis longus it 
abducts the hand. Nerve, the median. „ 
[Flexor! Palmaris Longus (Fig. 296).—' The long palmar [flexor] muscle. 
Situation, in the front of the forearm. Origin, the inner condyle of the humerus 
Direction downward and slightly outward. Insertion, the palmar fascia and 
anterior annular ligament. Action : it tightens the fascia of the palm, and then 
flexes the hand. Nerve, the median. . 
Flexor Carpi Ulnaris (Figs. 296, 298, 310).—' The flexor of the wrist on the 
ulnar side.” Situation, in the front and inner border of the forearm. Origin, 
one head • the inner condyle of the humerus; the other head : the inner side 
of the olecranon and the 'upper two-thirds of the hind border of the ulna 
Direction downward. Insertion, the pisiform, unciform, and fifth metacarpal 
bones. Action, flexion of the hand. In conjunction with the extensor carpi 
ulnaris it adducts the hand. Nerve, the ulnar f 
Extensor Carpi Radialis Longus (Figs. 299, 300).—' The long extensor of 
the wrist on the radial side.” Situation, in the outer border of the lorearm. 
Origin, the lower third of the external condylar ridge of the humerus, in- 270 
THE MUSCLES. 
tion, downward and a little backward. Insertion, the base of the second 
metacarpal, behind and on the radial side. Action, extension of the hand. 
In conjunction with the flexor carpi radialis it abducts the hand. Nerve, the 
rausculo-spiral. 
Fig. 296.—Superficial muscles 
of front of right forearm. 
(Testut.) 
Fig. 297.—Flexor carpi radialis 
of right side: outline and attach- 
ment-areas. (F. H. G.) 
Fig. 298.—Flexor carpi ulnaris 
of right side: outline and attach- 
ment-areas. (F. H. G.) 
Extensor Carpi Radialis Brevis (Figs. 299-301).—“The short extensor of the 
wrist on the radial side.” Situation, the outer border of the forearm. Origin, 
the outer condyle of the humerus. Direction, downward and a little backward. 
Insertion, the base of the third metacarpal bone, behind and on the radial side. 
Action, extension of the hand. Nerve, the posterior interosseus branch of the 
musculo-spiral. 
Extensor Carpi Ulnaris (Figs. 302, 310).—“The extensor of the wrist on the 
ulnar side.” Situation, the back of the forearm on the ulnar side. Origin, the EXTENSOR CARPI ULNA RIS. 
271 
Fig. 820.—Muscles in radial region of right forearm, and deep muscles in its dorsum. (Testut.) 272 
THE MUSCLES. 
external condyle of the humerus and the middle third of the posterior border of 
the idna. Direction, downward and inward. Insertion, the base of the fifth 
Fig. 300.—Extensor carpi radialis 
longus of right side: outline and at- 
tachment-areas. (F. H. G.) 
Fig. 301.—Extensor carpi radi- 
alis brevis of right side ; outline 
and attachment-areas. (F. H. G.) 
Fig. 302.—Extensor carpi ulnaris 
of right side; outline and attach- 
ment-areas. (F. EL G.) 
metacarpal bone on its dorsal aspect and ulnar border. Action, extension of 
the hand. In conjunction with the flexor carpi ulnaris it adducts the hand. 
Nerve, the posterior interosseous branch of the musculo-spiral. 
MUSCLES MOVING THE FINGERS 
and the Fifth Metacarpal Bone. 
(Those which are situated entirely in the hand are indicated by a star.) 
Flexors. 
Extensors. 
Flexor sublimis digitorum. 
Flexor profundus digitorum. 
*Flexor ossis metacarpi minimi digiti. 
* Flexor brevis minimi digiti. 
*Lumbricales. 
Extensor communis digitorum. 
Extensor minimi digiti. 
Extensor indicis. FLEXOR SUBLIMIS DIGITOR UM. 
273 
Abductors. 
Adductors. 
*lnterossei dorsales. 
* Abductor minimi digiti. 
*lnterossei palmares. 
Of the five of these muscles located mainly in the forearm two arise from the 
humerus, one from the humerus, radius, and ulna, and two from the ulna only, 
hvery one in the group is inserted into one or more of the fingers, excepting the 
flexor of the fifth metacarpal bone, which is admitted to this company of finger 
flexors on account of the similarity of its action. 
Flexor Sublimis Digi- 
torum (Figs. 303-305). 
u The superficial flexor of 
the digits”—meaning the 
four fingers as distinguish- 
ed from the thumb. Syno- 
nym, flexor perforatus, 
“the perforated flexor” 
Fig. 805.—Tendon of flexor 
sublimis perforated by tendon 
of flexor profundus. (Testut.) 
—from the openings 
through which the ten- 
dons of the deep flexor 
pass. Situation, in the 
front of the forearm 
and hand, deeper than 
the flexors of the whole 
hand, but superficial 
to the other flexors. 
Origin, first head : the 
inner condyle of the 
humerus ; second head : 
the inner border of the 
coronoid process of the 
ulna ; third head: the 
oblique line and part of 
the anterior border of 
the radius. Direction, 
downward to all of the 
Fig. 303.—Flexor sublimis digi- 
torum of right side. (Testut.) 
Fig. 304.—Flexor sublimis digitorum 
of ria-ht side; outline and attachment- 
areas. (F. H. G.) 
digits but the thumbs Insertion, by four tendons, each to the sides of a second 
phalanx As the tendons pass through the annular ligament, those for the middle 
and ring-fingers are side bv side in front, the others behind them. Each tendon 274 
THE MUSCLES. 
is accompanied by a tendon of the flexor profundus, and permits the passage of 
the latter through a split which occurs opposite the first phalanx. The separated 
halves become united behind the tendon of the deep flexor, opposite the base of the 
second phalanx, but almost immediately separate again, and are inserted into the 
sides of the second phalanx. The tendons are bound down to the phalanges by a 
ligamentous sheath. Action, primary, flexion of the second phalanges ; secondary, 
flexion of first phalanges. Nerve, the median. 
Flexor Profundus Digitorum (Figs. 306-308).—u The deep flexor of the digits ” 
—meaning the fingers as 
distinguished from the 
thumb. Synonym, flexor 
perforans, “ the perforat- 
ing flexor ”—from the 
fact that its four tendons 
perforate the correspond- 
Fig. 308.—Tendon of flexor pro- 
fundus perforating tendon of flexor 
sublimis. (Testut.) 
ing tendons of the flexor 
sublimis. Situation, deeply 
in the front of the fore- 
arm and hand. Origin, 
three-fourths of the inner 
and anterior surfaces of 
the ulna, the adjacent half 
of the interosseous mem- 
brane, and the common 
tendon of it and the flexor 
and extensor carpi ulnaris 
on the hind border of the 
ulna. Direction, down- 
ward. Insertion, each of 
the four tendons into the 
front of the base of a last 
phalanx. Each tendon 
perforates a tendon of the 
superficial flexor opposite 
Pig. 806.—Muscles in the 
right forearm, the deepest 
layer. (Testut.) 
Fig. 307—Flexor profundus digitorum 
of right side: outline and attachment- 
areas. (F. H. G.) 
the first phalanx ; each is bound to the first and second phalanges by ligaments 
which form a sheath common to this and the sublimis tendon. Action, flexion of 
third phalanges primarily, and, after this, flexion of the second, and, slightly, of 
the first. Nerves, the ulnar and the anterior interosseous branch of the median. FLEXOR BREVIS MINIMI DIGITI. 
275 
Flexor Ossis Metacarpi Minimi Digiti (Fig. 309).—“ The flexor of the meta- 
carpal bone of the least digit”—i. e., of the little finger. Synonyms, oppo- 
nens minimi digiti, and opponens digiti quinti, “ the opposing muscle of the least 
(or fifth) digit,” so called from its drawing the hypothenar eminence toward the 
thenar, thus narrowing and deepening the palm. Situation, deep in the hypo- 
Fig. 309.—Muscles of the right palm. The abductors of the thumb and little finger have been removed 
(Testut.) 
thenar eminence. Origin, the unciform process and the annular ligament. 
Direction, downward and toward ulnar margin of the hand. Insertion, the whole 
of the ulnar side of the fifth metacarpal. Action, flexion of the fifth metacarpal 
and slight adduction toward the mid-line of the hand. Nerve, the deep branch 
c> 
of the ulnar 
Flexor Brevis Minimi Digiti (Fig. 309).—“ The short flexor of the least digit ” 
—i. e., of the little finger. Synonym, flexor digiti quinti brevis, “ the short flexor 276 
THE MUSCLES. 
of tho fifth digit.” Situation, subcutaneously in the centre of the hypothenar 
eminence. Origin, the unciform process and the annular ligament. Direction, 
downward and inward. Insertion, the 
base of the first phalanx of the little finger 
on the ulnar border. Action, flexion of 
the first phalanx of the little finger. 
Nerve, the deep branch of the ulnar. 
Lumbricales (Fig. 309).—“ The earth- 
worm muscles,” from fancied resem- 
blance to angle-worms ((umhrici). Num- 
ber, four. Each is a lumbricalis. Situa- 
tion, in the palm on the plane of the 
flexor profundus digitorum. Origin of 
the first and second : the palmar aspect 
and radial border of the corresponding 
deep flexor tendon ; of the third and 
fourth : the two tendons between which 
Fig. 310.—Muscles in the dorsum of the right fore 
arm and hand. (Testut.) 
Fig. 311.—Extensor communis digitorum of 
right side : outline and attachment-areas. (F. H. G.) EXTENSOR COMMUNIS DIG IT OB UM. 
277 
each respectively lies. Direction, downward and then backward, on the radial side 
of the digits. Insertion, each to extensor communis tendon of corresponding finger 
on the radial side of the first phalanx. Action, flexion of the first phalanges, and 
extension of the second and third phalanges. The first and second slightly abduct 
the index and middle fingers from the middle line of the hand, the third and 
fourth slightly adduct the ring and little fingers to that line. Nerves, the median 
for the outer two, the ulnar for the inner two. 
Extensor Communis Digitorum (Figs. 310-312).—“ The common extensor of 
the digits”—i. e., of the fingers, as distinguished from the thumb. Situation, 
superficially on the back of the forearm and hand. Origin, the outer condyle of 
the humerus. Direction, 
downward. Insertion: each 
of the four tendons finally 
divides into three slips op- 
posite the first phalanx, and 
the middle one is attached 
to the back of the base of the 
second phalanx ; the others, 
after uniting, are attached 
to the back of the base of 
the third phalanx. The first 
tendon receives the inser- 
tion of the extensor indicis 
at the base of the finger ; the 
fourth tendon unites with 
Fig. 312.—Relations of the inter- 
osseous and lumbrical muscles to the 
extensor tendons. (Testut.) 
Fig. 313.—Extensor minimi digit! 
of right side: outline and attach- 
ment-areas. (Testut.) 
Fig. 314.—Extensor indicis of 
right side: outline and attach- 
ment-areas. (F. H. G.) 
that of the extensor minimi digiti at a similar point. The fourth divides : one 
part unites with the tendon of the medius, the other with that of the extensor minimi 
digiti. A stroma band connects the tendons of the ring and middle fingers. Action, 
extension of the fingers. The oblique branches at the sides of the third tendon 
greatly limit the extension of the ring finger, when its immediate neighbors are 278 
THE MUSCLES. 
flexed, and this fact explains the difficulty experienced by pianists in lifting the 
annularis separately from the keys. Nerve, the posterior interosseous branch of 
the musculo-spiral. 
Extensor Minimi Digiti (Figs. 310-313).—“The extensor of the smallest 
digit ”—i. e., of the little finger. Synonym., extensor digiti quinti proprius, “ the 
proper extensor of the fifth digit ”—“ proper ”to distinguish it from the part of 
the extensor communis which acts upon this finger. Situation, in the back of the 
forearm and hand. Origin, the external condyle of the humerus. Insertion : its 
tendon, which is commonly split, blends with the fourth tendon of the extensor 
communis above the metacarpo-phalangeal joint, and the resulting tendon goes 
to the second and third phalanges of the little finger (see extensor communis 
digitorum). Action, extension of the second and third phalanges of the little 
finger. Nerve, posterior interosseous branch of the musculo-spiral. 
Extensor Indicis (Figs. 299, 314).—“ The extensor of the index finger.” Syno- 
nyms, extensor indicis proprius, “the proper extensor of the index finger”— 
“ proper ” to distinguish it from the part of the extensor communis which acts 
upon this digit; the indicator muscle. Situation, the back of the lower part of 
the forearm and hand. Origin, the back of the ulna below the extensor longus 
pollicis, and a little of the interosseous membrane. Direction, downward and 
outward. Insertion, the first tendon of the extensor communis digitorum, near 
the metacarpo-phalangeal joint (see extensor communis digitorum). Action, exten- 
sion and slight adduction of the index. Nerve, the posterior interosseous branch 
of the musculo-spiral. 
Interossei Dorsales (Fig. 315).—“ The muscles between the bones on the back ” 
THIRD DORSAL 
interosseous" 
FOURTH DORSAL 
INTEROSSEOUS j 
SECOND DORSAL 
INTEROSSEOUS 
FIRST DORSAL 
INTEROSSEOUS 
Fig. 315.—Interossei dorsales of right hand. The line xx is that from which abduction is made. (Testut.) 
of the hand. Number, four. The first and largest is called abductor indicis, 
“ the abductor of the index finger.” The abductor minimi digiti belongs func- 
tionally in this group; but it is not interosseous. Situation, one in each meta- 
carpal interspace near the dorsal aspect. Origin, each from the two bones ABDUCTOR MINIMI DIGITI. 
279 
between which it lies. Direction, downward. Insertion, each into the base of a 
first phalanx, and also into the extensor tendon of the same finger, the first on 
the radial side of the index, the second on the radial side of the medius, the 
third on the ulnar side of the medius, the fourth on the ulnar side of the annularis. 
Action: each abducts from a line coinciding with the long axis of the middle 
finger. This digit, having two interossei inserted into it, is abducted toward the 
radial side by one, and toward the ulnar side by the other; thus, each in turn 
becomes an adductor, for the finger being abducted by one is then restored to the 
mid-line (i. e., adducted) by the other. They also flex the first phalanges and 
extend the second and third. Nerve, the deep branch of the ulnar. 
Fig. 316.- Muscles of the right palm. The palmaris brevis is reflected to the ulnar side. (Testut.) 
Abductor Minimi Digit! (Fig. 316).-“The abductor of the least digit’’-*, c., 
of the little finger. Synonym, abductor digiti qumti, the abductor of the htth 280 
THE MUSCLES. 
digit.” Situation, the ulnar border of the hand. Origin, the pisiform. Direc- 
tion, downward. Insertion, the ulnar border of the base of the first phalanx of 
the little finger and the tendon of the extensor minimi digit!. Action, abduction 
of little finger. Nerve, the ulnar. Its function puts it in the group with the 
interossei dorsales, as it draws its digit from the mid-line of the hand. 
FIRST PALMARE- 
INTEROSSEOUS 
THIRD PALMAR 
INTEROSSEOUS 
SECOND PALMAR 
INTEROSSEOUS 
Fig. 317.~Tnterossei palmares of right hand. The line xx is that to which adduction is made. (Testut.) 
Interossei Palmares (Fig. 317).—“The muscles between the bones in the 
palm.” Synonym, interossei volares. Number, three. Situation, in the second, 
third, and fourth metacarpal interspaces, near the palmar surfaces of the bones. 
Origin, the first: ulnar side of second metacarpal; the second : radial side of 
fourth metacarpal; the third : the radial side of the fifth metacarpal. Direction, 
downward. Insertion, each into the side of the base of the first phalanx of the 
digit from whose metacarpal bone it arises, and also into the corresponding ex- 
tensor tendon. Action, each adducts its digit toward the middle finger; also, it 
flexes the first phalanx of its digit, and extends the second and third phalanges. 
Nerve, the deep branch of the ulnar. 
MUSCLES MOVING THE THUMB 
and its Metacarpal Bone. 
(Those entirely in the hand are indicated with a star.) 
Extensors. 
*Flexor ossis metacarpi pollicis. 
*Flexor brevis pollicis. 
Flexor longus pollicis. 
Flexors. 
Extensor ossis metacarpi pollicis. 
Extensor brevis pollicis. 
Extensor longus pollicis. 
Abductor. 
Adductor. 
* Abductor pollicis. 
* Adductor pollicis. MUSCLES MO VING THE THUMB. 
281 
The movements of the first metacarpal bone are so closely associated with 
those of the phalanges which it carries, that it is profitable to consider its special 
muscles in the group with those of the thumb. The longer name of the meta- 
carpal flexor is preferred as indicating its action as well as “ opponens pollicis,” 
and at the same time expressing much more clearly the antagonism between it 
and the metacarpal extensor. 
Flexor Ossis Metacarpi Pollicis (Figs. 318, 309).—“The flexor of the meta- 
carpal bone of the thumb.” Synonym, opponens pollicis, “ the opponent muscle 
of the thumb ”—referring to its action in opposing the thenar eminence to the 
hypothenar, so that the palmar hollow is deepened and narrowed, and a body 
Fig. 318—Adductor pollicis, flexor ossis metacarpi pollicis, and pronator quadratus. (Testut.) 
between these muscular mounds can be grasped by them. Situation, deep in the 
thenar eminence. Origin, the palmar aspect of the trapezium and annular liga- 282 
THE MUSCLES. 
ment. Direction, downward and outward. Insertion, the whole shaft of the 
metacarpal bone of the thumb on its radial side and anterior aspect. Action, flex- 
ion and. inward rotation of the first metacarpal bone. Nerve, the median. 
Flexor Brevis Pollicis (Fig. 309).—“ The short flexor of the thumb.” Situation, 
deep in thenar eminence. Origin, outer (superficial) head : the trapezium and the 
outer two-thirds of the annular ligament; inner (deep) head : the proximal part 
of the first metacarpal on the ulnar side. Direction, downward and outward. 
Insertion, outer head : the outer side of the base of the first phalanx of the 
thumb ; inner head : the inner side of the same. In each tendon of insertion is 
a sesamoid bone. Action, flexion of the first 
phalanx of the thumb. Nerves, outer head : the 
median ; inner head : the ulnar. 
Flexor Longus Pollicis (Figs. 306, 319).— 
“ The long flexor of the thumb.” Situation, deep 
in the front part of the forearm, and on the pal- 
mar aspect of the thumb. Origin, the anterior 
surface of the radius from the oblique line to the 
upper line of the pronator quadratus, the adjacent 
part of the interosseous membrane, and sometimes 
the base of the coronoid process of the ulna. 
Direction, downward to the wrist, then downward 
and outward. Insertion, the front of the base of 
the last phalanx of the thumb. Action, flexion of 
the last phalanx of the thumb. Nerve, the ante- 
rior interosseous branch of the median. 
Extensor Ossis Metacarpi Pollicis (Figs. 320, 
321).—“The extensor of the metacarpal bone 
of the thumb.” Synonym, abductor longus pol- 
licis, “ the long abductor of the thumb.” Situa- 
tion, deep in the lower two-thirds of the back of 
the forearm and in the radial side of the wrist. 
Origin, small areas below attachments of supi- 
nator on botli radius and ulna, and the inter- 
osseous membrane between these surfaces. Di- 
rection, downward and outward. Insertion, the 
base of the metacarpal bone of the thumb. Ac- 
tion, extension and abduction of the metacarpal 
bone of the thumb. Nerve, posterior interosseous 
branch of the musculo-spiral. 
Extensor Brevis Pollicis (Figs. 320, 322).— 
“ The short extensor of the thumb.” Synonym, 
extensor primi internodii pollicis, “ the extensor 
of the first phalanx of the thumb.” Situation, 
deep in the lower half of the back of the fore- 
arm on the outer side, and in the metacarpus. 
Origin, a small area of the radius, just below the 
extensor ossis metacarpi pollicis, and the ad- 
jacent portion of the interosseous membrane. 
Direction, downward and outward. Insertion, 
the back of the base of the first phalanx of the 
thumb. Action, extension of the thumb. Nerve, 
the posterior interosseous branch of the musculo- 
spiral. 
Extensor Longus Pollicis (Figs. 320, 323).— 
Fig. 319—Flexor longus pollicis of 
right side; outline and attachment-areas. 
(F. H. G.) 
“ The long extensor of the thumb.” Synonym, extensor secnndi internodii pol- 
licis, “ the extensor of the second phalanx of the thumb.” Situation, deep in the 
lower half of the back of forearm and in the thumb. Origin, the middle third of EXTENSOR LONG US POLLIGTB. 
283 
Fig. 320.—Muscles in radial region of right forearm, and deep muscles in its dorsum. (Testut.) 284 
THE MUSCLES. 
the hind surface of the ulna, below the extensor ossis metacarpi pollicis, and 
the neighboring part of the interosseous membrane. Direction, downward and 
outward. Insertion, the back of the base of the last phalanx of the thumb. 
Action, extension of the last phalanx of the thumb. Nerve, the posterior inter- 
osseous branch of the musculo-spiral. 
Abductor Pollicis (Fig. 316).—“The abductor of the thumb.” Synonym, 
abductor pollicis brevis, “the short abductor of the thumb.” Situation, super- 
ficial, on radial side of metacarpal bone of the thumb. Origin, the front of the 
annular ligament, and, to a slight extent, the trapezium and scaphoid. Direction, 
downward and outward. Insertion, the base of the first phalanx of the thumb 
on the outer side. Action, abduction of thumb. Nerve, the median. 
Fig. 321.—Extensor ossis meta- 
carpi pollicis of right side : outline 
and attachment-areas. (F. H. G.) 
Fig. 322.—Extensor brevis pol- 
licis of right side: outline and at- 
tachment-areas. (F. H. G.) 
Fig. 323.—Extensor longus pol- 
licis of right side: outline and at- 
tachment-areas. (F. H. G.) 
Adductor Pollicis (Fig. 318).—“ The adductor of the thumb.” Situation, deep 
in the outer half the palm. Origin, one head : the os magnum, the bases of the 
second and third metacarpals, and the annular ligament; the other head ; the 
lower two-thirds of the third metacarpal. Direction, the upper part: downward 
and outward ; the lower part: outward. Insertion, the inner side of the base of PALMA BIS BREVIS. 
285 
the first phalanx of the thumb. Action, adduction and flexion of thumb. Nerve, 
the ulnar.—The upper portion of this muscle is often described as adductor 
ohliquus pollicis, and the lower as adductor transversus pollicis. 
The interossei, the abductor and adductor pollicis, and the abductor minimi 
digit! may well be considered together as constituting a distinct physiological 
group, the members of which are concerned either in abduction or adduction, or 
both (Fig. 324). Each of the five digits has attached to the base of its first 
Fig 324 -Diagram showing the arrangement of the adductors and abductors of the digits of the hand 
(F. H. G.) 
phalanx two of these ten muscles, one upon the radial, the other upon the ulnar 
side The thumb has the abductor and adductor pollicis; the forefinger has the 
' first dorsal interosseous (abductor indicis) and the first palmar interosseous (the 
adductor of the index): the ring finger has the second palmar interosseous (the 
adductor of the annularis) and the fourth dorsal interosseous (the abductor of 
Ikp nnnnlnrki • the little finger has the third palmar interosseous (the adductor of 
the least digit)'and the abductor minimi digiti. The lateral opponent muscles of 
the middle fino-er are the second and third dorsal interosseous—the one drawing 
the dio-it fromgthe middle line toward the radial side, the other drawing it from 
Ihe SHine toward the ulnar side-that is both are abductors But, 
the finger being displaced laterally by one of these muscles is restored to 
the middle line by the action of the other; and thus it is seen that the second 
and third dorsal interosseous are, on occasion, adductors as well as abductors. 
One other muscle must he described, although it is so diminutive and nearly powerless that 
it doesnot deserve a place in any of the specified groups. 
_ , . . ,-&• oii: v vThe short palmar muscle.” Situation, subcutaneous at 
Palmans Brevis ( „. • pie irlller border of the palmar fascia and the middle 
the proximal part ot the palm, on iym, 286 
THE MUSCLES. 
of the annular ligament. Direction, inward. Insertion, the skin at the inner border of the 
palm. Action, wrinkling the skin of the hypothenar eminence and slightly deepening the hol- 
low of the palm. Nerve, the ulnar. 
Although the classification of the muscles of the upper limb which has been 
given is regarded as the most helpful to the learner and to the practitioner, it is 
desirable that they should be studied from other points of view also; and, there- 
fore, a regional classification is herewith presented, based upon the situation of 
the main portion of each of these structures. 
Muscles which Move the Upper Limb, Grouped according to their 
Location. 
In the Superficial Layer of the Bach of the Trunk. 
Trapezius. 
Latissimus. 
In the Second Layer of the Back of the Trunk. 
Levator scapulae. 
Rhomboideus minor. 
Rhomboideus major. 
On the Front of the Chest. 
Pectoralis major. 
Subclavius. 
Pectoralis minor. 
On the Side of the Chest. 
Serratus magnus. 
In the Back Part of the Shoulder 
Supraspinatus. 
Teres major. 
Infraspinatus. 
Teres minor. 
Subscapularis. 
In the Older Part of the Shoulder. 
Deltoideus. 
In the Inner Side of the Arm. 
Coraco-brachialis. 
Biceps flexor cubiti. 
In the Front Part of the Arm. 
Brachialis. 
In the Back Part of the Arm. 
Triceps extensor cubiti. 
Pronator teres 
In the Front Part of the Forearm. 
Flexor carpi ulnaris. 
Flexor sublimis digitorum. 
Flexor profundus digitorum. 
Flexor carpi radialis. 
[Flexor] palmaris longus. 
Pronator quadratus. 
In the Outer Part of the Forearm. 
B rach i o-radialis. 
Extensor carpi radialis longus. 
Extensor carpi radialis brevis. THE MUSCLES OF THE LOWER LIMB. 
287 
In the Back Part of the Forearm. 
Anconeus. 
Extensor communis digitorum. 
Extensor minimi digiti. 
Extensor carpi ulnaris. 
Extensor ossis metacarpi pollicis. 
Extensor brevis pollicis. 
Extensor longus pollicis. 
Extensor iudicis. 
Supinator. 
In the Thenar Eminence. 
Abductor pollicis. Flexor brevis pollicis. 
Flexor ossis metacarpi pollicis. Adductor pollicis. 
In the Hypothenar Eminence. 
Abductor minimi digiti. Flexor brevis minimi digiti. 
Flexor ossis metacarpi minimi Palmaris brevis, 
digiti. 
In the Palm of the Hand between the Eminences. 
Lumbricales. Interossei palmares. 
Interossei dorsal es. 
The student is advised to make other classifications of the muscles moving 
the limbs, in order to obtain as complete a practical knowledge of them as pos- 
sible. For example, let him group the muscles according to the parts which they 
connect, under some such headings as the following : 
Connecting the head, neck, and (or) trunk with the shoulder. 
Connecting the trunk with the aim. 
Connecting the shoulder with the arm. 
Connecting the shoulder with the forearm. 
Connecting the arm with the foieaim. 
Connecting the bones of the forearm. 
Connecting the arm with the hand. 
Connecting the forearm with the hand. 
Connecting the parts of the hand with each other. 
Again, let him enumerate the muscles which would be cut by plane sections 
made transversely through the limb at diffeient levels, as, tor example, at the mid- 
dle of the arm, in the lower third of the arm, in the upper quarter of the fore- 
arm and so on. The more ways he adopts for considering the subject, the more 
exact, permanent, and usable will be his knowledge. 
THE MUSCLES OF THE LOWER LIMB. 
In makiim a physiological classification of the muscles of the lower limb, 
we notice at the outset that there is a great difference between the mobility of the 
first segment of the upper limb and that ot its homologue in the lower: the 
shouldex is freely movable, the hip is almost immovably fixed. There is no 
group of muscles devoted to moving the pelvic girdle at all comparable with 
those concerned in the movements of the shoulder. The great muscles of the 
abdominal wall lift the front of the pelvis; but this is accompanied to no appre- 
ciable extent by movement of the hip-bones at their articulations with the sac- 
rum but by the curving of the vertebral column. The very inconstant psoas 
parvus is sometimes asserted to flex the pelvis; but this may well be questioned, 288 
THE MUSCLES. 
and the muscle, which is frequently absent, probably has no effect except in tight- 
ening the iliac fascia. No group of muscles, therefore, will be presented as 
acting upon the hip. 
Movements of the Thigh.—The ball-and-socket joint at the hip permits move- 
ment of the thigh in every direction. That forward is called flexion, backward 
is extension, outward is abduction, inward is adduction. Rotation and circumduc- 
tion are like the same movements in the upper extremity. 
Movements of the Leg.—At the knee the joint is a hinge, and the movements 
of the leg are forward, which is extension, and backward, which is flexion. 
Between the two long bones of. the leg there is no movement comparable with the 
pronation and supination of the radius. 
Movements of the Foot.—At the ankle is another hinge with movement of the 
foot forward (upward), Avhich is flexion, and backward (downward), which is 
extension. The lateral movements of the foot are chiefly at the astragalo-calcanean 
and the medio-tarsal articulations. 
Movements of the Digits.—The metatarso-phalangeal and interphalangeal 
articulations are almost identical with their homologues in the hand, the main 
difference being that the first metatarsal is like all of its fellows in its practical 
immobility, and thus the hallux has nothing like the capacity of the pollex— 
there is no power of grasping in the sole as there is in the palm. Motion of the 
toes forward (upward) is extension, in the opposite direction is flexion. Thus, we 
see that the series of forward movements presents alternately flexion and extension 
—of the thigh flexion, of the leg extension, of the foot flexion, of the toes exten- 
sion ; and the backward movements are alternately, beginning with the thigh, 
extension and flexion. In the upper extremity the forward movements, it will 
be remembered, are all flexion. The movements of the toes sidewise are abduc- 
tion and adduction with reference to a line running through the normal long axis 
of the second digit of the foot, and not the third, as it is in the hand. 
Classification of the Muscles of the Lower Limb on the Basis 
of their Principal Action. 
Flexors. Extensor. 
Psoas magnus. Gluteus maximus. 
Iliacus. 
Moving the Thigh 
Abductors. Adductors. 
Tensor vaginae femoris. Adductor magnus. 
Gluteus medius. Adductor longus. 
Gluteus minimus. Adductor brevis. 
Adductor gracilis. 
Pectineus. 
Internal Rotators. External Rotators. 
(The same as the abductors.) Obturator externus. 
Quadratus femoris. 
Pyriformis. 
Gemellus superior. 
Obturator internus. 
Gemellus inferior. MUSCLES MOVING THE THIGH. 
289 
Moving 
the Leg-. 
Flexors. 
Extensor. 
Sartorius. Quadriceps extensor cruris, comprising : 
Biceps flexor cruris. Rectus femoris. 
Semitendinosus. Vastus externus. 
Semimembranosus. Vastus internus. 
Popliteus. Vastus intermedins. 
Moving- the Foot. 
Flexors. Extensors. 
Tibialis anterior. Tibialis posterior. 
Gastrocnemius. 
Soleus. 
Plantaris. 
Peroneus longus. 
Peroneus tertius. Peroneus brevis. 
Moving the Digits of the Foot. 
(Those situated entirely in the foot are indicated by a star.) 
Flexors. Extensors. 
Flexor longus hallucis. Fxtensor proprius hallucis. 
*Flexor brevis hallucis. 
Flexor longus digitorum. Extensor longus digitorum, 
*Flexor accessorius. 
*Flexor brevis digitorum. brevis digitorum. 
* Flexor brevis minimi digiti. 
*Lumbricales. 
Abductors. 
Adductors. 
* Abductor hallucis. * Adductor obliquus hallucis. 
* Abductor minimi digiti. * Adductor transversus hallucis. 
*lnterossei dorsales. *lnterossei plantares. 
MUSCLES MOVING THE THIGH. 
Flexors. Extensor. 
Psoas magnus. Gluteus maximus. 
Iliacus. 
Abductors and Internal Rotators. 
Tensor vaginae femoris. 
Gluteus medius. 
Gluteus minimus. 
Adductors. 
Adductor magnus. 
Adductor longus. 
Adductor brevis. 
Adductor gracilis. 
Pectineus. 
Obturator externus. Gemellus superior. 
Quadratus femoris. Obturator interims. 
Pvriformis. Gemellus inferior. 
19 
External Rotators. 290 
THE MUSCLES. 
The flexors of the thigh arise partly from the lumbar vertebrae, partly from the 
inner surface of the false pelvis, and are inserted upon the small trochanter. 
The great extensor arises from the back part of the hip-bone, sacrum, and 
coccyx, and is inserted into the small trochanter and the fascia lata. 
The abductors, which are also internal rotators, arise from the outer aspect of 
the hip-bone, and are inserted into the great trochanter and the neighboring fascia 
lata. 
The adductors arise from the hip-bone near the middle line of the body, and 
four of the five pass outward and downward with varying degrees of obliquity to 
their insertion into the back part of the shaft of the femur, the fifth one going 
below the knee-joint to the upper part of the tibial shaft. They are to a con- 
siderable extent external rotators. 
The external rotators arise partly from the inside and partly from the outside 
of the bony pelvis, and are all inserted about the upper end of the femur. 
Psoas Magnus (Figs. 325, 326).—“ The great loin muscle.” Synonym, psoas 
major. Situation, in the hind wall of the abdomen and upper part of the thigh. 
Origin, the front of the transverse processes and side of bodies of lumbar vertebrae 
Fig. 325.—Psoas, iliacus, and obturator externus muscles. (Testut.) 
and side of body of the last thoracic, with included intervertebral cartilages. 
Direction, down- and forward, and finally down- and backward. Insertion, the GLUTEUS MAXIMUS. 
291 
small trochanter of the femur. Action, flexion of the thigh. Nerves, the second 
and third lumbar. 
Iliacus (Figs. 325, 327).—“The iliac muscle.” Synonym, iliacus interims, 
“ the internal iliac muscle.” Situation, in iliac fossa and upper part of thigh. 
Origin, the upper two-thirds of the iliac fossa and the ala of the sacrum. Direc- 
Fig. 326.—Psoas magnus of right side; outline and 
attachment-areas. (P. H. G.) 
Fig. 327.—Iliaeus of right side: outline and attach- 
ment-areas. (F. H. G.) 
tion, down- and inward. Insertion, the tendon of the psoas magnus, the front of 
the small trochanter and the small surface below it. Action, flexion of the thigh. 
Nerve, the anterior crural. 
The two preceding muscles—psoas and iliaeus—are sometimes treated as 
one muscle, called ilio-psoas. 
Gluteus Maximus (Figs. 328, 329).—“ Tim largest muscle of the buttock.” 
Situation, subcutaneous in the back of the hip and upper part of the thigh. 
Origin, the hind fourth of the iliac crest, the outer surface of the ilium between 
the crest and the superior gluteal line, the hind surface of the lower two seg- 
ments of the sacrum and upper three of the coccyx, the great sacro-sciatic 
ligament, and the aponeurosis of the erector spinse. Direction, down- and outward. 
Insertion, the lower half to the gluteal ridge of the femur, the upper to the fascia 
lata Action extension and external rotation of the thigh. the inferior 
gluteal. 292 
THE MUSCLES. 
Fig. 328.—Gluteus maximus of right side. (Testut.) 
Fig. 329.—Gluteus maximus of right side; 
outline and attachment-areas. (F. H. G.) 
Tensor Vaginae Femoris (Figs. 330, 348).—“ The tightener of the sheath of the 
thigh.” Synonym, tensor fasciae latse, 
“ the tightener of the broad fascia.” 
Situation, in the front part of the outer 
aspect of the hip and thigh. Origin, 
the outer surface of the front part of 
the crest of the ilium. Direction, down- 
ward and slightly backward. Inser- 
tion, the fascia lata several inches below 
the great trochanter. Action, tighten- 
ing of the fascia lata, abduction and 
inward rotation of thigh. Nerve, the 
superior gluteal. 
Gluteus Medius (Figs. 331, 332).— 
“The middle buttock-muscle.” Situa- 
tion, in the outer part of the hip from 
the iliac crest to the trochanter major. 
Origin, the external surface of the 
ilium between the crest and the supe- 
rior and middle gluteal lines. Direc- 
tion, downward. Insertion, the outer 
surface of the trochanter major. Ac- 
tion, abduction of the thigh, and, when 
the thigh is flexed, inward rotation. 
Nerve, the superior gluteal. 
Gluteus Minimus (Figs. 333, 334). 
“ The smallest buttock-muscle.” Situa- 
tion, in the outer part of the hip, from 
the front part of the crest to the great 
Fig. 330.—Tensor vaginae femoris of right side 
outline and attachment-areas. (F. H. G.) 
trochanter. Origin, the external surface of the ilium, between the middle and GLUTEUS MINIMUS. 
293 
Fig. 331.—Muscles of right hip, viewed from be- 
hind, the gluteus maximus having been cut away. 
(Testut.) 
• —Gluteus medius of 
right side; outline and attachment- 
areas. (P. H. G.) 
Fig. 333.—Gluteus minimus of right side. (Testut.) 
Fig. 334.—Gluteus minimus of 
right side : outline and attachment- 
areas. (F. H. G.) 
inferior gluteal lines. Direction, down- and outward. Insertion, the front of 
the great trochanter. Action, abduction of the thigh, when it is extended ; 
inward rotation, when it is flexed. Nerve, the superior gluteal. 294 
THE MUSCLES. 
Fig. 335.—Adductores magnus and brevis of right side. (Testut.) 
Adductor Magnus (Figs. 335,336, 353).—“ The 
great adductor.” Situation, in the inner side of 
the thigh. Origin, the ramus of the os pubis, 
the ramus and tuberosity of the ischium. Direc- 
tion, from the ischial tuberosity downward ; from 
the pubic body outward, from the intermediate 
parts obliquely downward and outward. Inser- 
tion, the gluteal ridge, the inner lip of the linea 
aspera, the internal supracondylar ridge and the 
adductor tubercle. The femoral attachment is 
broken by several arches. Action, adduction and 
external rotation of thigh. The part from the 
ischial tuberosity is extensor. Nerves, the obtu- 
rator and the great sciatic. 
Adductor Longus (Figs. 337, 338).—“The 
long adductor,” Situation, in the inner side of 
the thigh. Origin, the body of the os pubis 
near the angle. Direction, down-, out-, and 
Fig. 336.-—Adductor magnus of right 
side: outline and attachment-areas. 
(F. H. G.) 
backward. Insertion, the inner lip of the linea aspera about the middle third ADDUCTOR LONG US. 
295 
Fig. 837.—Muscles in the right thigh, viewed from 
in front, after removal of the rectus and sartonus. 
(Testut.) 
Fig. 338.—Adductor longus of right side: outline 
and attachment-areas. (P. H. G.) 296 
THE MUSCLES. 
Fig, 339.—Adductor brevis of right side; outline 
and attachment-areas. (F. H. G.) 
Fig. 340.—Adductor gracilis of right side; outline 
and attachment-areas. (F. H. G.) PECTINEUS. 
297 
of the thigh. Action, adduction, flexion, and external rotation of thigh. Nerve, 
the obturator. 
Adductor Brevis (Figs. 335, 339).—“ The short adductor.” Situation, in the 
inner and upper part of the thigh. Origin, the outer surface of the body and 
descending ramus of the os pubis. Direction, down-, out-, and backward. Inser- 
tion, the line from the small trochanter to the linea aspera and the upper part of 
the linea aspera. Action, adduction, flexion, and external rotation of the thigh. 
Nerve, the obturator. 
Adductor Gracilis (Figs. 337, 340, 352).—“ The slender adductor.” Situation, 
in the inner side of the thigh near the surface. Origin, the inner margin of the 
os pubis, the lower half of the symphysis, and the whole length of the inferior 
ramus. Direction, downward, behind the inner condyle of the femur, and, below 
the knee, forward. Insertion, the upper part of the inner surface of the tibia. 
Action, adduction of thigh ; also, flexion and inward rotation of leg. Nerve, the 
obturator. 
Pectineus (Figs. 337, 341).—“ The pubic muscle.” Situation, between the 
pubic bone and the upper, back part of the thigh. Origin, the ilio-pectineal line 
Fig. 341.—Pectineus of right side; outline and 
attachment-areas. (F. H. G.) 
Fig. 342.—Obturator externus of right side: outline 
and attachment-areas. (F. H. G.) 
and the surface in front of it. Direction, down-, out-, and backward. Insertion, 
the rough line from the small trochanter to the linea aspera. Action, adduction, 298 
THE MUSCLES. 
flexion, and outward rotation of thigh. Nerves, the anterior crural and the obtu- 
rator. 
Obturator Externus (Figs. 335, 342).—“ The outer obturator muscle,” so called 
from its origin. Situation, between the obturator region on the outer surface of 
the pelvis and the digital fossa of the femur, behind and beneath the hip-joint. 
Origin, the inner half of the outer surface of the obturator membrane, the adjoin- 
ing surfaces of the pubic body, and the pubic and ischial rami. Direction, outward, 
then backward and upward, close to the under and hind surfaces of the cervix 
femoris. Insertion, the bottom of the digital fossa. Action, outward rotation, 
adduction, and flexion of thigh. Nerve, the obturator. 
Quadratus Femoris (Figs. 331, 333, 343).—“The square muscle of the thigh.” 
Situation, between the tuber ischii and the upper part of the shaft of the femur. 
Fig. 343.—Quadratus femoris of right side: outline and attachment-areas. (F. H. G.) 
Origin, the outer border of the tuberosity of the ischium. Direction, outward. 
Insertion, the quadrate tubercle and the surface just below it. Action, external 
rotation and adduction of thigh. Nerve, from the sacral plexus. 
Pyriformis (Figs. 344, 345).—“ The pear-shaped muscle.” Situation, between 
the front of the hind wall of the true pelvis and the upper end of the thigh. 
Origin, the ventral surface of the second, third, and fourth pieces of the sacrum, 
between and outside of the anterior foramina and the hind border of the ilium 
below the inferior spine. Direction, nearly horizontally outward by the great 
sacro-sciatic foramen. Insertion, the front of the upper border of the great tro- 
chanter. Action, when the femur is extended, external rotation; when it is 
flexed, abduction. Nerve, from the sacral plexus. 
The obturator internus and the two gemelli are so intimately related that it 
would be rational to consider them as a single muscle; but, as they are always 
treated as separate organs, the conventional rule is here observed. 
Gemellus Superior (Fig. 344).—“ The upper little twin muscle.” Situation, 
above the tendon of the obturator internus. Origin, the spine of the ischium. 
Direction, outward. Insertion, the front of the inner surface of the great tro- OBTURATOR INTERN US. 
299 
chanter. Action, assistant to the obturator interims. Nerve, from the sacral 
plexus. 
Obturator Interims (Fig. 346).—“ The internal obturator muscle,” referring to 
Fig. 344.—Muscles of right hip viewed from behind, the 
gluteus maximus having been cut away. (Testut.) 
Fig. 345.—Pyriformis of right side : outline 
and attachment-areas. (F. H. G.) 
its origin. Situation, largely within the pelvis on its lateral wall, and partly in 
the upper end of the thigh. Origin, the inner surface of the obturator mem- 
Fig. 346. Obturator interims of right side. The gemellus superior is shown, but the inferior is mostly 
removed. (Testut.) 
brane, except a little of its lower part; a large area between the obturator fora- 
men, ilio-pectineal line, and the great sacro-sciatic foramen; the front and lower 300 
THE MUSCLES. 
Fig. 347.—Sartorius of right side: outline and 
attachment-areas. (F. H. G.) 
Fig. 348.—Superficial muscles in front part of the 
right thigh. (Testut.) MUSCLES MOVING THE LEG. 
301 
margins of the latter foramen. Direction, backward to the small sacro-sciatic 
foramen, around the ischium, and thence outward. Insertion, the front part of 
the inner surface of the great trochanter. Action, in extension of the thigh, exter- 
nal rotation; in flexion of the thigh, abduction. 
Gemellus Inferior (Fig. 344).—“ The lower little twin muscle.” Situation, 
below the tendon of the obturator interims. Origin, the upper part of the 
tuberosity of the ischium. Direction, outward. Insertion, the front of the inner 
surface of the great trochanter. Action, assistant to the obturator interims. 
Nerve, from the sacral plexus. 
MUSCLES MOVING THE LEG. 
Flexors. 
Sartorius. 
Biceps flexor cruris. 
Semitendinosus. 
Semimembranosus. 
Popliteus. 
Extensor. 
Quadriceps extensor cruris, comprising : 
Rectus femoris. 
Vastus externus. 
Vastus internus. 
Vastus intermedins. 
Of the five flexors three arise from the pelvis alone, one from the pelvis and 
femur, and one from the femur alone. Thus, four of them cross both the hip- 
and the knee-joints, and become extensors of the thigh, whenever flexion of the 
leg is prevented or fully accomplished. 
One head of the multiple extensor arises from the pelvis, the others from the 
femur. The part which crosses the hip-joint as well as the knee-joint acts as a 
flexor of the thigh, when extension is completed or the knee is fixed. 
Sartorius (Figs. 347, 348, 352).—“The tailor’s muscle,” so called from its 
action, which assists in producing the cross-legged position assumed by tailors in 
sitting on the bench. Situation, in the front and inner side of the thigh, between 
the ilium and tibia. Origin, the anterior superior iliac spine and part of the 
notch below. Direction, downward and inward across the front of the thigh, 
then behind the inner condyle of the femur, and finally forward. Insertion, the 
inner surface of the tibia, near the tubercle. Action, flexion of the leg and thigh, 
and synchronous abduction of the thigh; then outward rotation. Nerve, the 
anterior crural. 
Biceps Flexor Cruris (Figs. 349, 350, 352).—“The two-headed flexor of 
the leg.” Situation, in the back of the thigh, between the ischium and fibula. 
Origin, the long head : the inner impression on the ischial tuberosity, in com- 
mon with the semitendinosus; the short head: the outer lip of the linea 
aspera and the upper two-thirds of the outer supracondylar ridge. Direction, 
downward and a little outward. Insertion, the head of the fibula and (slightly) 
the outer tuberosity of the tibia. Its tendon forms the outer hamstring. Action, 
flexion of the leg, and then external rotation; also, from its pelvic origin, exten- 
sion of the thigh. Nerve ot the long head, the internal popliteal; of the short 
head, the external popliteal. 
Semitendinosus (Figs. 349, 351, 352).—“ The half-tendon muscle.” Situation, 
in the back of the thigh toward the inner side, between the ischium and tibia. 
Origin, the inner impression of the ischial tuberosity, in common with the 
biceps. Direction, downward and a little inward. Insertion, the upper part of 
the inner surface of the tibia. Action, flexion of the leg, and then inward rota- 
tion ; also, from its pelvic origin, extension of the thigh. Nerve, the internal 
popliteal. 
Semimembranosus (Figs. 353, 354, 349).—“ The half-membrane muscle,” so 
called from the peculiar disposition of its tendons. Situation, in the hind and 
inner part of the thigh, from the ischium to the tibia. Origin, the upper and 
outer facet of the ischial tuberosity. Direction, downward and a little inward. 302 
THE MUSCLES. 
Insertion, mainly the groove on the back of the inner tuberosity of the tibia; 
also, a reflection upward and outward to the posterior ligament of the knee, 
and one downward and outward to the fascia covering the popJiteus. Action, 
flexion of leg, and then inward rotation; 
also, extension of thigh. Nerve, the in- 
ternal popliteal. The tendons of this 
muscle, the semitendinosus, and the 
gracilis from the inner hamstring. 
Popliteus (Figs. 353,355).—“ The ham 
muscle.” Situation, behind the knee- 
joint and in the upper part of the leg. 
Origin, the outer side of the external 
Fig. 349.—Muscles in the dorsum of the right 
thigh. (Testut.) 
Fig. 350.—Biceps flexor cruris of right side; outline 
and attachment-areas. (P. H. G.) 
condyle of the femur, within the capsule of the joint. Direction, down- and 
inward. Insertion, the triangular surface above the oblique line of the MUSCLES MOVING THE LEG. 
303 
tibia. Action, flexion and inward rotation of the leg. Nerve, the internal 
popliteal. 
Quadriceps Extensor Cruris.—“ The four-headed extensor of the leg/’ Syno- 
nym, quadriceps extensor femoris, “ the 
four-headed extensor of the thigh ”—a 
misleading name considered from the phys- 
iological point of view, because this muscle 
does not extend the thigh. 
General Description.—Three of the four 
heads arise from the femur, one from the 
ilium. Each segment is described as a 
separate muscle, but all unite in a common 
tendon of insertion, which is attached to 
the tubercle of the tibia. The lowest part 
of this tendon is usually called the liga- 
mentum patellae • but, philosophically con- 
sidered, it is tendon rather than ligament, 
and the patella is only a sesamoid bone 
developed in it, exactly as such osseous 
formations appear in the short flexor ten- 
dons of the great toe. The iliac part of 
the quadriceps is distinct from the rest 
nearly to the patella; but the others are 
more or less blended, and enclose the shaft 
Fig. 351.—Semitendinosus of right side: outline 
and attachment-areas. (F. H. G.) 
Fig. 352.—The inner hamstring muscles at their 
insertion. (Testut.) 
of the femur to such an extent as to leave hardly anything of it uncovered 
excepting the linea aspera. The four component parts are the rectus femoris, 304 
THE MUSCLES. 
vastus externus, vastus interims, and vastus intermedins, and they will be 
described separately. 
Rectus Femoris (Figs. 348, 356).—“The straight muscle of the thigh.” Situa- 
Situa 
lion, subcutaneous, in the 
front of the thigh. Origin, 
one head : the anterior infe- 
rior iliac spine; the other 
head : the surface just above 
the acetabulum. Direction, 
downward and slightly in- 
ward. Insertion, the upper 
Fig. 353.—Muscles in deep portion 
of dorsum of right thigh, the semi- 
tendinosus and most of the biceps 
having been removed. (Testut.) 
Fig. 354.—Semimembranosus of right 
side: outline and attachment-areas. (F. 
H. G.) 
Fig. 855. -- Popliteus 
of right side: outline and 
attachment-areas. (F. H. 
G.) 
border of the patella. Action, extension of the leg; also, from its iliac origin, 
slight flexion of the thigh. Nerve, the anterior crural. MUSCLES MO VING THE LEG. 
305 
Fig. 356.—Rectus femoris of right side; outline 
and attachment-areas. (F. H. G.) 
Fig. 357.—Muscles in the right thigh, viewed from 
in front, after removal of the rectus and sartonus. 
(Testut.) 306 
THE MUSCLES. 
Fig. 358.—Vastus externus of right side : outline 
and attachment-areas. (F. H. G.) 
Fig, 359.—Vastus interims of right side; outline 
and attachment-areas. (F. H. G.) MUSCLES MO VINO THE LEG. 
307 
Vastus Externus (Figs. 357, 358, 348).—“ The outer immense muscle.” Syno 
nym, vastus lateralis, “ the lateral immense muscle.” 
Situation, the outer part of the thigh, mostly sub- 
cutaneous. Origin, the anterior intertrochanteric 
line, the base of the great trochanter, the gluteal 
ridge, and the outer lip of the linea aspera. Direc- 
tion, down- and forward, then downward and 
inward. Insertion, the upper and outer borders 
of the patella. Action, extension of the leg. Nerve, 
the anterior crural. 
Vastus Internus (Figs. 357, 359, 348).—“ The 
internal immense muscle.” Synonym, vastus medi- 
alis, “ the immense muscle toward the median 
line.” Situation, in the inner part of the thigh, 
mostly subcutaneous. Origin, the spiral line of 
the femur, the inner lip of the linea aspera, and 
the internal supracondylar ridge ; also, the tendons 
of the adductor longus and adductor magnus. 
Direction, down- and forward, then down- and 
outward. Insertion, the inner and upper borders 
of the patella. Action, extension of the leg. Nerve, 
the anterior crural. 
Vastus Intermedius (Figs. 360, 361).—“ The 
Fig. 360.—Vastus intermedius of right side. 
Fig. 361.—Vastus intermedius of 
right side: outline and attachment- 
areas. (F. H. G.) 
(Testut.) 308 
THE MUSCLES. 
intermediate immense muscle/’ Synonym, crureus, “the leg muscle”—the com- 
mon name, but very faulty, because it implies location in the leg, whereas this 
is a muscle altogether in the thigh. Situation, close to the shaft of the femur. 
Origin, the upper two-thirds of the anterior surface of the femur, the outer 
surface in front of and below the origin of the vastus externus, and the lower 
half of the external intermuscular septum. Direction, mainly downward. Inser- 
tion, the upper border of the patella. Action, extension of the leg. Nerve, the 
anterior crural. A narrow interval, extending downward from near the small 
trochanter, separates the vastus intermedius from the internus. Close to the 
bone the intermedius and externus are blended, but are distinct from each other 
elsewhere. 
Slightly distal to the lowest part of the origin of the vastus intermedius a few small 
fasciculi arise from the ventral surface of the femur and pass downward to the proximal 
part of the synovial membrane of the knee-joint. They are usually spoken of as the sub- 
crureus, but would better be called musculus articularis genu, “the knee-joint muscle.” 
MUSCLES MOVING THE WHOLE FOOT. 
Flexors. 
Extensors. 
Tibialis anterior, 
(On the 
inner side.) 
Tibialis posterior. 
{Gastrocnemius. 
Soleus. 
Plantaris. 
/ Peroneus longus. 
\ Peroneus brevis. 
(Central 
group.) 
Peroneus tertius, 
(On the 
outer side.) 
All of these muscles find insertion in the foot, and all arise entirely in the 
leg, excepting one, which has its origin upon the thigh, and, since it crosses both 
knee- and ankle-joints, is a flexor of the leg, when the foot is fixed or fully 
extended. 
The extensors are more numerous and powerful than the flexors, the group 
which occupies the central position in the leg acting upon the foot purely as 
extensors. The inner and outer muscles respectively turn the foot inward and 
outward in addition to their work of flexion and extension. 
Tibialis Anterior (Figs. 362, 363).—“ The anterior tibial muscle.” Synonym 
and commoner name, tibialis anticus. Situation, in the front part of the leg and 
inner side of the foot. Origin, the external tuberosity and upper two-thirds of 
the outer surface of the tibia, and the front of the corresponding and adjacent 
portion of the interosseous membrane. Direction, downward and inward. Inser- 
tion, the inner surface of the internal cuneiform and the hind end of the first 
metatarsal. Action, flexion of foot and elevation of its inner border ; also adduc- 
tion of front of foot. Nerve, the anterior tibial. 
Peroneus Tertius (Figs. 362, 364).—“ The third fibular muscle.” Situation, 
in the front of the leg and dorsum of the foot. Origin, the lower fourth of the 
anterior surface of the fibula, and the corresponding and adjacent portion of the 
interosseous membrane. Direction, downward, then forward and outward. Inser- 
tion, the upper surface of the base of the fifth metatarsal. Action, flexion of the 
foot, elevation of its outer border, and abduction of its front end. It is insepar- 
able at its origin from the extensor longus digitorum. 
Tibialis Posterior (Figs. 365, 366,374, 378).—“The hind tibial muscle.” 
Synonym and commoner name, tibialis posticus. Situation, deep in the back part 
of the leg and inner part of the foot. Origin, the hind surface of the interosseous 
membrane, the upper half of the contiguous portion of the tibia, and the inner sur- 
face of fibula. Direction, downward and inward to the back of the inner mal- 
leolus, then forward. Insertion, the tuberosity of the navicular, with offshoots to MUSCLES MOVING THE WHOLE FOOT. 
309 
the three cuneiform, the cuboid, the bases of the second, third, and fourth meta- 
tarsal, and the sustentaculum tali. Action, extension of the foot, elevation of its 
inner border, and adduction of its front end. Nerve, 
the posterior tibial. 
Gastrocnemius (Figs. 367, 368, 371).—“ The belly- 
of-the-leg (or calf) muscle.” Situation, superficial in 
the back of the leg. Origin, the outer head : the 
outer side of the external condyle of the femur, and 
the surface just above ; the inner head : the upper part 
of the inner condyle, and the lower end of the ridge 
above. Direction, downward. Insertion, the hind part 
of the tuberosity of the calcaneum, in common with the 
Fig. 363.—Tibialis anterior of right 
side • outline and attachment-areas, 
(F. H. G.) 
Fig. 364.—Peroneus tertius of right 
side : outline and attachment-areas. 
(F. H. G.) 
Fig. 362.—Muscles in the right 
leg, viewed from in front. (Testut.) 
soleus. Action, extension of the foot; also, when the ankle-joint is fixed, flexion 
of the leg. Nerve, the internal popliteal. 310 
THE MUSCLES. 
Fig. 3Gs.—Tibialis posterior of right side. (Testut.) 
Pig. 366.—Tibialis posterior of right side: 
outline and attachment-areas. The most of the 
muscle is represented as if seen through the 
bones. (P. H. G.) MUSCLES MOVING THE WHOLE FOOT. 
311 
Fig. 367.—Gastrocnemius of right side. (Testut.) 
Fig. 368.—Gastrocnemius of right side: out- 
line and attachment-areas. (F. H. G.) 312 
THE MUSCLES. 
Fig. 369.—-Soleus and plantaris of right side. 
(Testut.) 
Fig. 370.—Soleus of right side : outline and 
attachment-areas. (F. H. G.) MUSCLES MOVING THE WHOLE FOOT. 
313 
Soleus (Figs. 369—371).—“ The sole-fish muscle,” so called from its shape. 
Synonym, gastrocnemius interims,” the internal belly-of-the-leg muscle.” Situa- 
tion, in the back part of the leg, in front of the gastrocnemius. Origin, the head 
Fig. 371.—Muscles in the outer side of right leg and dorsum of foot. (Testut.) 
and upper third of the hind surface of the fibula, and the oblique line and inter- 
nal border of the tibia to the middle of its shaft. Direction, downward and a 314 
THE MUSCLES. 
little backward. Insertion, the hind part of the tuberosity of the calcaneura, in 
common with the gastrocnemius. Action, extension of the foot. Nerves, the 
internal popliteal and posterior tibial. 
The gastrocnemius and solens are sometimes and not fancifully considered as 
a single muscle under the name of triceps surer, “ the three-headed muscle of the 
calf”—the former furnishing two heads, and the latter, one. The common tendon 
is called tendo calcaneus, “ the heel tendon,” and also more commonly, tendo 
Achillis, “ the tendon of Achilles,” in allusion to the legendary hero, whose only 
vulnerable part was his heel. This tendon is the largest in the body, is about six 
Fig. 372.—Peroneus longus of right side: outline 
and attachment-areas. (F. H. G.) 
Fig. 373.—Peroneus brevis of right side : outline and 
attachment-areas. (F. H. G.) 
inches long, narrowest at the level of the ankle-joint, and receives muscular 
fibres almost to its insertion. 
Plantaris (Fig. 369).—“ The sole-of-the-foot muscle,” referring to its occasional 
insertion into the plantar fascia. Situation, in the back of the leg between the 
gastrocnemius and soleus. Origin, the ridge above the external condyle of the MUSCLES MOVING THE WHOLE FOOT. 
315 
Fig. 374.—Muscles in the deep layer of the dorsum of the 
right leg. (Testut.) 
. Fig. 375.—Flexor longus hallueis of right 
side: outline and attachment areas. The 
muscle is represented as seen from the front 
through the bones. (F, H. G.) 316 
THE MUSCLES. 
femur. Direction, downward and inward. Insertion, the calcaneum at the inner 
side of the tendo Achillis. Action, extension of foot and flexion of leg. Nerve, 
the internal popliteal. 
Peroneus Longus (Figs. 371, 372, 374, 378).—“ The long fibular muscle,” 
Situation, in the outer side of the leg and the sole of the foot. Origin, the outer 
tuberosity of the tibia, the head and upper two-thirds of the outer surface of the 
fibula. Direction, downward to the back of the outer malleolus, forward on the 
outer side of the calcaneum, through the groove of the cuboid, inward and 
forward across the sole. Insertion, the base of the first metatarsal and the inter- 
nal cuneiform. Action, extension of the foot, elevation of its outer edge, and 
abduction of its front end. Nerve, the musculo-cutaneous of the external 
popliteal. 
Peroneus Brevis (Figs. 371,373, 365, 378).—“The short fibular muscle.” 
Situation, in the outer side of the leg and foot. Origin, the lower two-thirds of 
the outer surface of the fibula. Direction, downward to behind the external 
malleolus, then forward and a little downward. Insertion, the outer side of the 
tuberosity of the fifth metatarsal. Action, extension of the foot, elevation of its 
outer edge, and abduction of its front end. Nerve, the musculo-cutaneous of the 
external popliteal. 
MUSCLES MOVING THE DIGITS OF THE FOOT. 
(Those situated entirely in the foot are indicated by a star.) 
Flexor longus hallucis, 
* Flexor brevis hallucis. 
Flexor longus digitorum. 
* Flexor accessorius. 
* Flexor brevis digitorum. 
*Flexor brevis minimi digiti. 
*Lumbricales. 
Flexors. 
Extensors. 
Extensor proprius hallucis. 
Extensor longus digitorum. 
*Extensor brevis digitorum. 
Abductors. 
Adductors. 
* Abductor hallucis. 
* Abductor minimi digiti. 
*lnterossei dorsales. 
* Adductor obliquus hallucis. 
* Adductor transversus hallucis. 
*lnterossei plantares. 
In studying the muscles moving the digits of the foot it is unnecessary to 
place in a group by themselves those which act upon the great toe, as was done in 
the case of those of the thumb, for the reason that the first metatarsal bone is as 
fixed as its four fellows, and does not permit the degree and kind of movement 
which are so marked a feature of digital action in the hand. 
All but four of the twenty-four members of this group are situated entirely 
in the foot. 
Flexor Longus Hallucis (Figs. 374, 375, 378).—“ The long flexor of the great 
toe.” Synonym, flexor longus pollicis pedis, “ the long flexor of the thumb of 
the foot.” Situation, deep in the back of the leg on the outer side and in the 
sole. Origin, the lower two-thirds of the hind surface of the fibula, and a little of 
the interosseous membrane below. Direction, downward and inward, behind the 
inner malleolus, beneath the sustentaculum tali, then forward and inward in the 
sole. Insertion, the under surface of the base of the last phalanx of the first 
digit. Action, flexion of the last phalanx of the great toe. Nerve, the posterior 
tibia!. MUSCLES MOVING THE DIGITS OF THE FOOT. 
317 
Flexor Brevis Hallucis (Figs. 376, 379).—“The short flexor of the great toe.” 
Synonym, flexor brevis pollicis pedis, “ the short flexor of the thumb of the foot.” 
Situation, in the third layer of the muscles 
of the sole on the inner side.1 Origin, the 
inner border and under surface of the cuboid, 
and the cuneiform tendon of the tibialis pos- 
terior. Direction, forward and inward. Inser- 
tion, one (the inner) tendon : the inner side of 
the base of the first phalanx of the great toe 
on the plantar aspect, fused with the abductor; 
the other tendon : the outer side of the same 
bone, symmetrical with the inner tendon, and 
conjoined with the adductor. Action, flexion 
of the whole of the great toe. Nerve, the internal 
plantar. 
Flexor Longus Digitorum (Figs. 374, 377, 
378).—“The long flexor of the digits” of the 
foot, meaning the four small toes. Synonym, 
flexor perforans digitorum pedis, “ the perforat- 
ing flexor of the digits of the foot,” referring 
to the passage of its tendons of insertion through 
the corresponding tendons of the flexor brevis 
digitorum. Situation, deep in the back of the 
leg on the inner side, and in the sole. Origin, 
the middle two-fourths of the inner part of the 
hind surface of the tibia. Direction, downward 
behind the inner malleolus, then forward and out- 
ward into the sole. Insertion, by four tendons, 
each into the base of a third phalanx on the 
plantar surface. The undivided tendon is super- 
ficial to that of the flexor longus hallucis. Each 
digital tendon perforates the corresponding ten- 
don of the flexor brevis, just as the flexor pro- 
fundus perforates the flexor sublimis in the hand. 
„ 876.—Muscles in the third layer 
of the right sole. (Testut.) 
Action, flexion of the last phalanges of the four small toes. Nerve, the posterior 
tibial. 
Flexor Accessorius (Fig. 379).—“The adjunct flexor,” this being assistant to 
the flexor longus digitorum. Synonyms, flexor accessorius digitorum pedis, and 
quadratus plan he, “ the square muscle of the sole.” Situation, in the hind part 
of the second muscular layer of the sole. Origin, the calcaneum—one head 
being attached to the inner surface, the other the outer surface in front of the 
external tubercle. Direction, forward. Insertion, the outer (hind) border and 
upper surface of the flexor longus digitorum. Action, flexion of the four small 
toes. It also brings the line of action of the flexor longus digitorum into the long 
axis of the foot. Nerve, the external plantar. 
Flexor Brevis Digitorum (Fig. 380),—“ The short flexor of the digits,” mean- 
ing the four small toes. Synonym, flexor perforatus digitorum pedis, “ the per- 
forated flexor of the digits of the foot.” Situation, in the first muscular layer 
or the sole, midway between its sides. Origin, the front of the inner tubercle 
of the calcaneum. Direction, forward. Insertion, by four tendons into the sides 
of the second phalanges of the four small toes on their plantar aspect. Each 
tendon is perforated opposite the first phalanx by the corresponding tendon of 
the long flexor. Action, flexion of the second phalanges of the four small toes. 
Nerve, the internal plantar. 
Flexor Brevis Minimi Digiti Pedis (Fig. 379).—“The short flexor of the least 
1 The layers of plantar muscles are numbered from the surface of the sole upward, as they occur 
in dissection. 318 
THE MUSCLES. 
digit of the foot”—i.e., of the little toe. Synonym, flexor digit! quinti brevis, 
“ the short flexor of the fifth digit.” Situation, in the third muscular layer of the 
sole on its outer border. Origin, the under surface 
of the base of the fifth metatarsal. Direction, 
forward. Insertion, the outer side of the base of 
the first phalanx of the fifth toe on its plantar 
aspect. Action, flexion of the fifth toe. Nerve, 
the external plantar. 
Lumbricales (Fig. 379).—“The earth-worm 
muscles,” from their fancied resemblance to com- 
mon angle-worms (lumhrici). Each is a lumbri- 
calis. Number, four. Situation, in the fore part 
of the second muscular layer of the sole. Origin, 
from the digital tendons of the flexor longus cligi- 
torum. Direction, forward to the inner side of the 
four small toes. Insertion, the extensor tendon 
on the dorsum of the first phalanx. Action, first, 
flexion of the first phalanges; second, extension 
Fig. 377.—Flexor longus digitorum of 
right side: outline and attachment-areas. 
The muscle is represented as seen from in 
front through the bones. (F. H. G ) 
Fig. 378.—Tendons in the right sole. (Testut.) 
of second and third phalanges. Nerves, for the inner two, the internal plantar ; 
for the others, the external plantar. MUSCLES MOVING THE DIGITS OF THE FOOT 
319 
Extensor Proprius Hallucis (Figs. 381, 382, 362).—“ The proper extensor of 
the great toe.” Synonyms, extensor longus hallucis, extensor proprius pollicis, 
extensor longus pollicis pedis. “ Proprius ”is preferable to “ longus ”in naming 
this muscle, because extension of the great toe is partly effected through the 
inner tendon of the extensor brevis digitorum, a muscle not special (proprius) to 
Fig. B79—Flexor accessorius and lumbricales 
of right foot. (Testut.) 
. , If1®- 880.-—Muscles of the superficial layer of the 
right foot. (Testut.) 
this digit, but also concerned in extending three other toes. Situation, in the front 
of the leg and dorsum of the foot. Origin, the middle two-fourths of the anterior 
surface of the fibula and adjacent part of the interosseous membrane. Direction, 
downward, through the annular ligament, then forward, inward, and a little 
downward. Insertion, the dorsum of the base of the last phalanx of the hallux. 
Action, extension of great toe. Nerve, the anterior tibia!. 
Extensor Longus Digitorum (Figs. 362, 383).—“ The long extensor of the 
digits,” meaning the four small toes. Situation, in the front of the leg and dor- 
sum of the foot. Origin, the external tuberosity of the tibia, the head and two- 
thirds of the anterior surface of the fibula, and a little of the upper part of the 
interosseous membrane. Direction, downward through the annular ligament, 
then forward and a little downward. Insertion, by a tendon for each of the 
small toes. Each tendon divides into three parts, of which the middle is attached 
at the base of the second phalanx on its dorsal aspect, the lateral parts uniting 
and finding attachment at the base of the last phalanx. Action, extension of 
the four small toes. Nerve, the anterior tibial. 
Extensor Brevis Digitorum (Figs. 384, 381).—a The short extensor of the 320 
THE MUSCLES. 
digits” of the foot. Situation, in the dorsum of the foot. Origin, the front of 
the upper and outer surface of the calcaneum. Direction, forward, and a little 
inward and downward. Insertion, by four tendons : the first at the base of the 
Fig. 381.—Muscles in the outer side of right leg and dorsum of foot. (Testut.) 
first phalanx of the great toe on its dorsal aspect; the others on the outer borders 
of the long extensor tendons of the second, third, and fourth toes respectively. MUSCLES MOVING THE DIGITS OF THE FOOT. 
321 
Action, of first tendon : extension of first phalanx of the great toe, and slight adduc- 
tion ; of the others : assistance to the long extensor. Nerve, the anterior tibiah 
It should be observed that this muscle does not act upon just the same digits 
as does the long extensor. The extensor brevis is inserted into the great toe, but 
not into the little; the extensor longus into the little toe, but not into the great. 
Fig. 382.—Extensor proprius hallucisof right side: 
outline and attachment-areas. (F. H. G.) 
Fig. 883.—Extensor longus digitorum of right side 
outline and attachment-areas. (F. H. G.) 
Abductor Hallucis (Figs. 380, 381).—“ The abductor of the great toe.” 
Synonym, abductor pollicis pedis, “ the abductor of the thumb of the foot,” 
Situation, in the first muscular layer of the sole on the inner side. Origin, the 
inner tubercle of the calcaneum. Direction, forward and a little inward. Inser- 
tion, the inner side of the base of the first phalanx of the great toe, conjoined 
with the inner head of the flexor brevis hallucis. Action, abduction and flexion 
of the great toe. Nerve, the internal plantar. 
Abductor Minimi Digiti Pedis (Figs. 380, 384),—“ The abductor of the smallest 
digit of the foot.” Synonym, abductor digiti quinti, “the abductor of the fifth 
digit.” Situation, in the first muscular layer of the sole on the outer side. 322 
THE MUSCLES. 
Origin, both tubercles of the calcaneum. Direction, forward and a little outward. 
Insertion, the outer side of the base of the first phalanx of the little toe. Action, 
abduction of the fifth digit. Nerve, the external plantar. 
Interossei Dorsales Pedis (Fig. 385).—“ The dorsal interosseous muscles of the 
foot.” Number, four. Situation, one in each of the four spaces between the 
metatarsal bones. Origin, each from the adjacent sides of two metatarsal bones. 
Direction, forward. Insertion, the bases of the first 
phalanges, as follows : the first to the inner side of 
the second toe, the second to the outer side of the 
second toe, the third to the outer side of the third 
toe, the fourth to the outer side of the fourth toe; 
FOURTH DORSAL. 
INTEROSSEOUS 
THIRD DORSAL- 
INTEROSSEOUS 
SECOND DORSAL 
INTEROSSEOUS 
, FIRST DORSAL 
INTEROSSEOUS 
Fig. 384.—Extensor brevis digi- 
torum of right foot. (Testut.) 
Fig. 385.—Interossei dorsales of right foot. The line xx is 
that from which abduction is made. (Testut.) 
also, each to the extensor tendon of the corresponding toe. Action: each 
abducts from a line, drawn through the long axis of the second toe. Those 
acting on the second toe are alternately abductors and adductors: when one of 
them has abducted the toe, the other restores it to its attitude of rest by adduction. 
The dorsal interossei also flex the first phalanges, and afterward extend the second 
and third. Nerve, the external plantar. 
Adductor Obliquus Hallucis (Fig. 386).—“ The oblique adductor of the great 
toe.” Synonym, adductor pollicis pedis, “ the adductor of the thumb of the foot.” 
Situation, in the fore and middle part of the third muscular layer of the sole. 
Origin, the proximal ends of the second, third, and fourth metatarsals. Direc- 
tion, forward and inward. Insertion, the outer side of the base of the first 
phalanx of the great toe, in common with the adductor transversus and the 
outer head of the flexor brevis hallucis. Action, adduction and flexion of the 
great toe. Nerve, the external plantar. 
Adductor Transversus Hallucis (Fig. 386).—“ The transverse adductor of the 
great toe.” Synonym, transversus pedis, “ the transverse muscle of the foot.” 
Situation, in the third muscular layer of the sole, across the distal end of the 
metatarsus. Origin, the lower metatarso-phalangeal ligaments of the outer three 
toes and the transverse metatarsal ligament. Direction, transversely inward. MUSCLES MOVING THE DIGITS OF THE FOOT. 
323 
Insertion, the base of the first phalanx of the great toe, conjointly with the 
adductor obliquus and the outer head of the flexor brevis. Action, adduction 
of great toe. Nerve, the external plantar. 
Interossei Plantares (Fig. 387).—“ The plantar interosseous muscles.” Number, 
three. Situation, the second, third, and fourth spaces between the metatarsal bones, 
on the plantar aspect. Origin, the inner and 
under surfaces of metatarsal bones, as follows : 
the first on the third bone, the second on the 
fourth, the third on the fifth. Direction, forward. 
Insertion, each on the inner side of the base of 
the first phalanx of the corresponding toe and 
•THIRD PLANTAR 
INTEROSSEOUS 
SECOND PLANTAR 
'' INTEROSSEOUS 
FIRST PLANTAR 
INTEROSSEOUS ~ 
Fig. 386.—Muscles in the third layer of 
the right sole. (Testut.) 
Fig. 387.—Interossei plantares of right foot. The line xx is 
that to which adduction is made. (Testut.) 
its extensor tendon. Action, adduction toward the second toe; also, flexion of 
the first phalanges, and afterward extension of the second and third phalanges. 
Nerve, the external plantar. 
The interosseous muscles, the abductor and the two adductors of the hallux, 
and the abductor minimi digit! are physiologically upon the same plane, forming 
a group whose members produce the lateral movements of the toes. The great 
toe has one muscle (abductor hallucis) inserted on the inner side of the base of 
the first phalanx, and two adductors on the opposite side of the same bone; each 
of the other toes has two muscles similarly attached. They are arranged as fol- 
lows, the inner muscle in each case being named first: the second toe has the first 
dorsal interosseous and the second dorsal interosseous; the third toe has the first 
plantar interosseous and the third dorsal; the fourth toe has the second plantar 
interosseous and the fourth dorsal; the fifth toe has the third plantar interosseous 
and the abductor minimi digit!. The interossei inserted upon the second toe are 
alternately abductors and adductors; the other dorsal interossei are always 
abductors, and all of the plantar interossei are adductors, the middle line of the 
second toe when at rest being the line from and to which movements are reckoned. 
Compare the arrangement with that of the homologous parts in the upper limb. 
Psoas Parvus (Fig. 325).—“ The little loin-muscle ”is small, flat, inconstant, of irregu- 
lar origin, situated in front of the psoas magnus. Most frequently it arises from the bodies of 324 
THE MUSCLES. 
the lowest thoracic and the highest lumbar vertebrae and the disc between them. Its body is 
short, and its long tendon, blended with the iliac fascia, is inserted into the ilio-pectineal emi- 
nence. It is a tensor of the iliac fascia. 
Muscles which Move the Lower Limb, Grouped According to Their 
Location. 
In the Pelvis and Upper Part of the Thigh. 
Psoas magnus. Iliacus. 
In the Region of the Buttock 
Obturator externus. 
Gemellus superior. 
Obturator interims. 
Gemellus inferior. 
Gluteus maximus. 
Gluteus rneclius. 
Gluteus minimus. 
Pyriformis. 
Quadratics fern oris. 
Tensor vagi me femoris. Vastus exteruus. 
Sartorius. Vastus interims. 
Rectus femoris. Vastus intermedius. 
In the Front of the Thigh 
In the Bach of the Thigh 
Semimembranosus. Semitendinosus. 
Biceps flexor cruris. 
In the Mesial Part of the Thigh. 
Adductor maguus. Adductor brevis. 
Adductor longus. Adductor gracilis. 
Pectineus. 
In the Front of the Leg 
Tibialis anterior. Extensor proprins hallucis. 
Extensor longus digitorum. Peroneus tertins. 
In the Outer Part of the Leg. 
Peroneus longus 
Peroneus brevis. 
In the Bach of the Leg. 
Gastrocnemius, d 
Soleus. > Superficial group. 
Plantaris. j 
Popliteus. 
Flexor longus hallucis. I 
Flexor longus digitorum. ( 1 a 1 
Tibialis posterior. J 
In the Dorsum of the Foot. 
Extensor brevis digitorura. 
In the Sole of the Foot. 
Abductor hallucis. d 
Flexor brevis digitorum. V First (superficial) layer. 
Abductor minimi digit!. } 
Flexor accessorius. 1 &c(wd 
Lumbncales. j u 
Flexor brevis hallucis. 
Adductor obliquus hallucis. I TUrd k 
Adductor transversus hallucis. 
Flexor brevis minimi digit!. J 
Interossei plantares. I Fourth layer. 
Interossei dorsales pedis. J 17 THE MUSCLES OF THE BA CK. 
325 
THE MUSCLES OF THE TRUNK. 
These will be considered in three groups, as follows : 
A. The muscles of the hack, including those in the dorsum of the neck. 
B. The muscles of the abdomen. 
C. The muscles of the thorax. 
THE MUSCLES OF THE BACK, 
including the Dorsum of the Neck. 
The muscles situated in the back of the trunk and neck are arranged in a 
number of groups, which are usually described as layers, although the lamination 
of those most deeply located is not distinct. 
The first, or superficial layer, comprising the trapezius and latissimus, and the 
second, layer, made up of the levator scapulae and the two rhomboidei, have already 
been described in connection with the muscles of the upper limb, as they func- 
tionally belong in that class. 
Muscles in the Third Layer of the Back. 
Serratus posterior superior. Splenius capitis. 
Serratus posterior inferior. Splenius cervicis, 
Fig. 388.—Muscles in the third layer of the back. (Testut.) 
Serratus Posterior Superior (Fig. 388).—“ The upper, hind, saw-toothed muscle.” 
Synonym, serratus posticus superior. Situation, at the base of the neck and upper 
part of the thorax, nearly covered by the levator scapulae and rhomboidei. Ori- 326 
THE MUSCLES. 
gin, the lower part of the nape ligament, and the spines of the last cervical and 
two or three upper thoracic vertebra1. Direction, 
down- and outward. Insertion, the second, third, 
fourth, and fifth ribs beyond their angles. Action, 
elevation of the ribs of its insertion. Nerves, the 
second and third intercostals. 
Serratus Posterior Inferior (Fig. 389).—“ The 
lower, hind, saw-toothed muscle.” Synonym, ser- 
ratus posticus inferior. Situation, the upper loin 
and lower thoracic regions. Origin, the spines 
of the lower two thoracic and upper two or three 
lumbar vertebrae. Direction, outward and upward. 
Insertion, the lower borders of the lower four or 
five ribs, beyond the line of the costal angles. 
Action : it draws the lower ribs backward and 
downward. Nerves, the intercostal. 
Splenius Capitis (Fig. 388).—“ The strap- 
shaped muscle of the head.” Situation, in the 
back of the neck, in front of the trapezius. 
Fig. 389—Muscles in the second layer of 
the back and on the dorsum of the shoulder. 
(Testut.) 
Fig. 390.—Erector spime, superficial 
view. (Testut.) THE MUSCLES OF THE BACK. 
327 
Origin, the lower two-thirds of the nape ligament, and the spines of the seventh 
cervical and first and second thoracic vertebrae. Direction, upward and outward. 
Insertion, the mastoid process of the temporal, and the superior curved line of 
the occipital. Action, extension of head, and its rotation to the side on which 
the muscle lies. Nerve, the posterior primary branches of the middle cervical. 
Splenius Cervicis (Fig. 388).—“ The strap-shaped muscle of the neck.” 
Synonym, splenius colli. Situation, in the back of the neck, in front of the trape- 
zius. Origin, the spines of the third, fourth, and fifth thoracic vertebrae. Direc- 
tion, upward, outward, and forward. Insertion, the hind tubercles of the trans- 
verse processes of the upper two, three, or four cervical vertebrae. Action, 
extension of the neck, and its rotation to the side on which the muscle lies. 
Nerves, the posterior branches of the lower cervical. 
The fourth layer is formed by the erector spinse (the erector of the spine— 
that is, the muscle which extends it). It constitutes the greater part of the long, 
rounded mass, which runs parallel to the series of vertebral spinous processes, 
and projects so far backward that, when a view is taken of the entire back, the 
bones seem to be sunk in a valley between two mounds, instead of protruding 
conspicuously, as in the skeleton. 
The Erector Spinse (Fig. 390) is a compound muscle, beginning below in a 
single mass, but soon dividing into three portions, which pass upward and end at 
different heights, that nearest the middle line going no further than the upper 
part of the thorax, the outermost passing well into the neck, and the middle 
reaching to the base of the skull. The second and third of these do not proceed 
to their respective destinations uninterruptedly, but by a series of steps, each 
making three. The arrangement suggests the simile of scaling a cliff; as the 
muscle climbs up the back, it does not relinquish one foothold until it has estab- 
lished a new one—it takes a fresh grip before it lets go the old; and, as a result, 
there is not merely continuity of structure, but overlapping, one segment begin- 
ning back (sometimes far back) of the ending of the segment below it. The 
various portions are described as separate muscles. The name erector spinse 
properly includes them all; but it is often used in a restricted sense to designate 
the undivided mass from which these prolongations arise. 
Muscles in the Fourth Layer of the Back. 
Scheme of the Erector Spince. 
Outer division : 
Ilio-costalis. 
Accessorius ad ilio-costalem. 
Cervicalis asceudens. 
Erector spinse 
Middle division : 
Longissiraus dorsi. 
Transversalis cervicis. 
Trachelo-mastoideus. 
Inner division: 
Spinalis dorsi. 
The Erector Spinae arises from the lowest two or three thoracic and all of the 
lumbar and sacral spines, the transverse processes of several lower thoracic ver- 
tebrae, the lower and back part of the sacrum, and the hind fifth of the iliac 
crest. From this beginning come the three divisions—the outer, the middle, 
and the inner. 
Tiie outer division starts off just below the last rib as the ilio-costalis (Fig. 
390), so called from its connecting the ilium with certain ribs. It is also known 328 
THE MUSCLES. 
Fig. 391.—Erector spinse. The outer series is pulled 
outward. (Testut.) 
Fig. 392.—Erector spinse. The middle series is 
pulled outward. (Testut.) THE MUSCLES OF THE BACK. 
329 
as the sacro-lumbalis, as it begins in the sacral region and runs to the lumbar. It 
is inserted into the lower six or seven ribs at their angles, or in the line of the cos- 
tal angles. From the same ribs, a trifle toward the middle line from these 
points of insertion, springs the accessorius ad ilio-costalem (Fig. 391), “ the adjunct 
to the ilio-costalis,” which passes up and is inserted into the upper six ribs (at the 
angles of those below the first, and on that one near the tubercle), and the trans- 
verse process of the vertebra prominens. On the four or five ribs above those 
from which the accessorius arises, a little mesially from its line of costal insertion, 
are the points of origin of the cervicalis ascendens (Fig. 391), “the ascending neck 
muscle/’ which thus sustains a relation to the accessorius like that of the latter to 
the ilio-costalis. It is inserted into the transverse processes of the fourth, fifth, 
and sixth cervical vertebrae. These three muscles—the ilio-costalis, accessorius, 
and cervicalis ascendens—are in appearance and in effect practically one. 
The middle and largest division of the erector spina begins as the longissimus 
dorsi (Figs. 390-392), “ the longest muscle of the back.” It is inserted into the 
transverse processes of all the thoracic and the accessory processes of the lumbar 
vertebrae, and into most of the ribs between the tubercles and angles. Its upward 
prolongation is called transversalis cervicis (Figs. 390, 392), a name which refers 
to the attachments of the muscle to transverse processes. It arises from the 
transverse processes of from four to six upper thoracic vertebrae, internally to the 
insertions of the longissimus, and is inserted into the transverse processes of cer- 
vical vertebrae from the second to the sixth. The last segment of this division is 
the trachelo-mastoideus (Figs. 391, 393), “ the neck-mastoid muscle,” so called from 
its situation and insertion. It arises from the transverse processes of from four 
to six upper thoracic vertebrae with the transversalis cervicis, and also from the 
articular processes of the lower three or four cervical ; and it is inserted into the 
mastoid process of the temporal. 
The third and smallest division is nearest the median line, and is given off 
from the main mass of the erector above the middle of the thorax. It is called the 
spinalis dorsi (Fig. 390), “ the spinal muscle of the back,” with reference to its 
bony attachments. It is a continuation of that portion of the common mass 
which arises from the lumbar and thoracic spines, and is inserted into the spines 
of a variable number of vertebrae in the upper thoracic region. 
The effect of this arrangement is such that the erection of the vertebral 
column is accomplished, not as it would be by a muscle which had no attach- 
ments between the sacrum and cranium, but by a continuous succession of con- 
tractions from one small division of the column to another only a short distance 
awav. Thus, a variety of actions is effected, and strength and steadiness of move- 
ment insured. 
The nervous supply of the entire series comes through the dorsal primary 
branches of the spinal nerves. 
Muscles in the Fifth Group of the Back. 
The fifth series of muscles lies in front of the erector spina?. They are all 
characterized by the direction of their fibres, which is from below upward and 
inward. Nearly all of the points of origin are on transverse processes of ver- 
tebra?, and most of the insertions are on spinous processes, the fibres passing from 
a transverse process to the spinous process of the fourth, fifth, or sixth vertebra 
above. They are the following : 
Complexes. Multifidus. 
Semispinalis cervicis; liotatores. 
Semispinalis dorsi, _ < 
Complexus (Figs. 393, 391), “the intricate muscle,” sometimes is called semi- 
spinalis capitis, but without good reason ; for the term “semispinalis” in con- 
nection with other muscles is used to signify that one attachment is upon spinous 
processes of vertebrae. It arises from the transverse processes of the upper six 330 
THE MUSCLES. 
or seven thoracic vertebra and the last cervical, and from the articular processes 
of cervical vertebrae from the third to the sixth. It is inserted into the 
occipital bone, on the mesial part of the surface 
between the curved lines. The portion nearest 
the middle line is somewhat detached, and has 
a tendinous inscription about half way of its 
length, on account of which it is often reckoned 
as a separate muscle, the biventer cervicis. It 
extends the head, drawing it to one side. Its 
nerve-supply is from several upper cervical 
nerves. 
Semispinalis cervicis (Fig. 392), the name 
meaning “ the muscle of the neck, one extremity 
of which is attached to spinous processes,” arises 
from the transverse processes of the upper five 
or six thoracic vertebra, and is inserted into 
the spinous processes of cervical from the second 
to the fifth. It extends the neck, and rotates it 
to the opposite side. Its nerves are branches 
from the lower cervical and upper thoracic. 
Semispinalis dorsi (Fig. 392), “ the muscle of 
the back, one end of which is attached to 
spinous processes,” arises from the transverse 
processes of thoracic vertebra from the sixth 
to the tenth, and is inserted into the spinous 
processes of the last two cervical and of the 
upper four, five, or six thoracic vertebra. Its 
principal action is extension of the lower cervi- 
cal and upper thoracic regions. It is supplied 
by thoracic spinal nerves. 
Fig. 393—Trachelo-mastoid and com- 
plexus. (Testut.) 
Multifidus (Fig. 392), “ the many-cleft muscle,” occupies the greater part of the 
gutter beside the vertebral spines from the sacrum to the axis. Its fibres pass 
from some part (usually a process) of one vertebra to the spinous processes of 
several vertebra above it, generally the second, third, and fourth. It arises from 
the groove on the back of the sacrum, the mammillary processes in the lumbar 
region, the transverse in the thoracic region, and the articular of the lower four 
cervical vertebra, and is inserted into all the spinous processes of the true ver- 
tebra. It extends, bends sidewise, and rotates to the opposite side the spinal 
column. The posterior branches of the spinal nerves supply it. 
Rotatores, rotators of the spine, lie covered in by the multifidus, and are by 
some regarded as part of it. They are constant only in the thoracic region, are 
eleven in number, and each passes between the transverse process of one vertebra 
and the lamina of the next above. They produce rotation of the spine to the 
opposite side, and also bend it backward and sidewise. Their nerves are the 
thoracic. 
In the cervical and lumbar regions are found a series of small muscles, called 
interspinales, which pass from one spinous process to the next above ; and another 
series, the intertransversales (intertransversarii), which connect one transverse pro- 
cess with the next above. The former assists in extension of the spine, the latter 
in its lateral flexion. 
Suboccipital Muscles. 
Rectus capitis posterior major. 
Rectus capitis posterior minor. 
Obliquus capitis inferior. 
Obliqnus capitis superior. 
Rectus Capitis Posterior Major (Fig. 392).—The name means literally “ the 
greater straight hind muscle of the head.” It arises from the spine of the axis, THE MUSCLES OF THE ABDOMEN. 
331 
passes upward and outward, and is inserted into the outer part of the inferior 
curved line of the occipital, and the surface in front of it. It extends the head, 
and rotates it to the same side. The suboccipital nerve supplies it and all the 
others of this group. 
Rectus Capitis Posterior Minor (Fig. 392), “ the smaller straight hind muscle 
of the head,” arises on the tubercle of the posterior arch of the atlas, runs 
upward and outward, and is inserted into the inner part of the inferior curved 
line of the occipital and the area in front of it. It extends the head. 
Obliquus Capitis Inferior (Fig. 392), “ the lower oblique muscle of the head,” 
arises from the spine of the axis, goes upward and outward, and is inserted into 
the transverse process of the atlas. Its principal action is to rotate the atlas to 
the same side. 
Obliquus Capitis Superior (Fig. 392), “ the upper oblique muscle of the head,” 
arises from the transverse process of the atlas, passes upward, backward, and 
inward, and is inserted into the surface behind the inferior curved line of the 
occipital. It extends the head. 
THE MUSCLES OF THE ABDOMEN. 
Rectus abdominis. 
Pyramidalis. 
Obliquus externus abdominis. 
Obliquus interims abdominis. 
Transversalis. 
Quadratus lumborum. 
Of these muscles the rectus and pyramidalis are in front, the quadratus is 
behind, and the contractile portion of the obliquus externus, obliquus interims, 
and transversalis are at the side, their fibrous part ex- 
tending forward and inward to the median line of the 
belly. 
Rectus Abdominis (Fig. 394).—■“ The straight mus- 
cle of the abdomen.” Situation, in the front wall of 
the belly. Origin, the pubic crest and symphysis, the 
tendon from the latter point coming from the opposite 
side and crossing its fellow. Direction, upward, curv- 
ing with convexity forward, corresponding with the 
contour of the belly. Insertion, the fifth, sixth, and 
seventh costal cartilages. Several tendinous intersec- 
tions (inscriptiones tendinece), usually not occupying the 
whole thickness of the muscle, cross it, generally one 
at the level of the ensiform appendix, one at that of the 
navel, one between these, and often one below. The 
sheath of the muscle is formed by the tendons of the 
lateral muscles. (See below.) Action, depression of 
the thorax, and compression of the abdominal vis- 
cera. Nerves, the lower intercostal and the ilio-hypo- 
gastric. 
The three lateral muscles constitute three nearly 
co-extensive layers, and their broad tendons of inser- 
tion (called “ aponeuroses ”), separate at first, become 
blended along a slightly curved, nearly vertical line 
(called linen semilunaris, “the half-moon line”) just at 
the outer edge of the rectus. This combined tendon 
then splits vertically into laminae of equal thickness, 
which separate and embrace the rectus, one going in 
front, the other behind, and finally meet again at the 
median line, where they fuse with each other and with 
the corresponding structures of the opposite side, mak- 
Fig. 394.—Rectus abdominis 
and obliquus internus of right 
side. (Testut.) 
ing a strong, perpendicular, fibrous band called tinea alba, “ the white line,” 
which runs from ensiform appendix above to symphysis pubis below. The 332 
THE MUSCLES. 
inclusion of the rectus by these tendons obtains, however, only in the upper three- 
fourths of its extent: the tendons all pass in front of the muscle in the lower 
quarter, leaving the corresponding hind surface free. 
Pyramidalis (Fig. 394).—“ The pyramidal muscle.” It arises from the front 
of the os pubis, runs up in the sheath of the rectus a short distance, and is inserted 
in the linea alba. It is very inconstant in presence, size, and shape. It is 
adjunct to the rectus. 
Obliquus Externus Abdominis (Fig. 395).—“ The external oblique muscle of 
the abdomen.” Situation, superficial, in the side and front walls of the belly. 
Origin, the outer surface of the lower eight ribs. 
Direction, downward in the hind part; downward, 
forward, and inward elsewhere. Insertion, the front 
half of the outer lip of the iliac crest, the pubic spine 
and crest, the ilio-pectineal line, and the linea alba. 
The points of origin make a saw-toothed line, the 
upper digitations interlocking with similar points of 
the serratus magnus, the lower with those of the latis- 
simus. The tendon of insertion is a broad sheet, 
which passes to the mid-line, and there fuses with its 
fellow opposite and with the tendons of the external 
oblique and transversalis. The part of the tendon 
extending from the anterior superior iliac spine to the 
pubic spine is thicker than the rest, and its edge is 
curled backward, forming a narrow shelf. This thick 
part is the inguinal ligament, commonly called Pou- 
part’s ligament. From its pubic end extends back- 
ward to the neighboring extremity of the ilio- 
pectineal line a flat, triangular process, having a free, 
concave outer border, and known as Girnbernat’s 
ligament, or the lacunar ligament. Just above the 
pubic body the tendon presents an opening, the exter- 
nal abdominal ring (Fig. 396), which results from a 
separation of the fibres. The aperture slopes upward 
and outward, and would be triangular were it not for 
certain fibres, which cross all but the lowest and widest 
inch of it, and are called intercolumnar, because they 
are between the pillars, as the inner (upper) and 
outer (lower) edges of the tendon, which margin the 
sides of the hole, are called. The inner pillar runs to 
Fig. 395.—Obliquus externus 
abdominis of right side. (Testut.) 
the symphysis, the outer to the spine of the pubic bone, ihus, the ring is 
bounded below by the pubic crest, above by the inner pillar, outside by the inter- 
columnar fibres, and elsewhere by the outer pillar. The ring is occupied by the 
spermatic cord in the male, by the round ligament of the womb in the female. 
Action, compression of abdominal viscera, rotation of the pelvis to the same side, 
flexion of pelvis on chest. Nerves, the lower intercostal, ilio-inguinal, and ilio- 
hypogastric. 
Obliquus Internus Abdominis (Fig. 394).—“The internal oblique muscle of the 
abdomen.” Situation, in the side and front of the belly-wall, next deeper than 
the external oblique. Origin, the outer half of the inguinal ligament, two-thirds 
of the middle lip of the iliac crest, and, slightly, the lumbar fascia. Direction, 
in general, forward, inward and upward ; also, directly upward behind, and down- 
ward in front. Insertion, the lower borders of the costal cartilages from the 
twelfth to the seventh, the ensiform appendix, the linea alba, the front of the os 
pubis, and the ilio-pectineal line. The portion inserted into the pubic bone and 
ilio-pectineal line enters into the formation of the conjoined tendon of the internal 
oblique and transversalis. The lower portions of the internal oblique give off a 
series of muscular slips, which are arranged in loops in front of and embracing THE MUSCLES OF THE ABDOMEN. 
333 
the spermatic cord. They constitute the cremaster muscle (“ the supporting mus- 
cle ”), and the fascia in the spaces between them is the cremasteric fascia. The 
Fig. 396.—External abdominal ring of right side. (Testut.) 
cremaster lifts the testicle. Action, the internal oblique compresses the abdominal 
viscera, depresses the ribs, flexes the chest upon the pelvis, and rotates it to the 
side on which the muscle acts. Nerves, the ilio-hypo- 
gastric, ilio-inguinal, and lower intercostals. 
Transversalis Abdominis (Fig. 397).—“ The trans- 
verse muscle of the abdomen.” Synonym, transversus 
abdominis. Situation, deep in the side and front 
walls of the belly. Origin, the inner surfaces of the 
lower six costal cartilages, the transverse processes of 
the lumbar vertebrae, the anterior two-thirds of the 
inner lip of the iliac crest, and the outer third of the 
inguinal ligament. Direction, forward and inward, and 
in lowest part downward. Insertion, the linea alba 
and (by the conjoined tendon of this muscle and the 
internal oblique) the front of the os pubis and the 
neighboring part of the ilio-pectineal line. The trans- 
versalis at its upper origin interdigitates with the 
diaphragm. Between its costal and iliac regions its 
origin is tendinous, and lies between the erector spin* 
and quadratus lumborum. This tendon is otherwise 
known as the middle layer of the lumbar fascia, and 
extends from the last rib to the ilio-lumbar ligament. 
Action, compression of the abdominal viscera. Nerves, 
the lower intercostal, ilio-hypogastric, and ilio-in- 
guinal. The muscular fibres at the upper third of the 
transversalis extend toward the middle line so far as 
to lie behind the rectus. 
It is well to note that the three muscles in the side 
of the abdomen are attached to ribs or costal cartilages 
above and to iliac crest below, respectively, as follows : 
the outer muscle to the outer surface and outer lip, the 
inner muscle to the inner surface and inner lip, the mid- 
Fig. 397.—Transversalis ab- 
dominis of right side. (Testut.) 
dle muscle to the middle surface (the border) and the middle lip. The obliquity 334 
THE MUSCLES. 
of the fibres of these muscles to each other contributes greatly to the strength of 
the abdominal wall, and is a safeguard against hernia. 
Quadratus Lumborum (Fig. 325).—“ The square muscle of the Joins.” Situa- 
tion, in the hind wall of the abdomen. Origin, the back part of the inner lip of 
the iliac crest, the ilio-lumbar ligament, and the transverse processes of several 
lower lumbar vertebrae. Direction, upward. Insertion, the last rib and the trans- 
verse processes of several upper lumbar vertebrae. Action, depression of last rib, 
and lateral flexion of spine. Nerves, the last thoracic and the upper lumbar. 
THE MUSCLES OF THE THORAX. 
Diaphragma. 
Intercostales extend. 
Intercostales intend. 
Leva tores costarum. 
Triangularis sterni. 
Subcostales. 
Diaphragma (Figs. 398, 399).—“ The diaphragm,” meaning etymologically 
“ a partition.” Synonym, the midriff. The diaphragm is the septum between 
Fig. 898.—Diaphragm, viewed from in front. (Testut.) 
the two great cavities of the trunk, forming the convex floor of the thorax and 
the vaulted roof of the abdomen. Its tendon is centrally located, and is, conse- 
quently, its highest part; and to this the muscular portion, which is peripheral, 
rises from its extensive origin at the lower boundaries of the thoracic framework 
—the sternum, some costal cartilages, several vertebra;, and certain fibrous bands 
between these vertebrae and the last rib. 
From the front of the bodies of the upper two lumbar vertebrae (on the right 
side one or two more) and the related cartilages rise two processes, called crura, 
which unite and arch over the aorta just below the last thoracic vertebra, the 
mesial fibres crossing to the opposite side. From the body of the first lumbar 
vertebra springs a fibrous band, which arches over to the tip of the transverse 
process, and from this point to the last rib a second band is stretched. The first THE MUSCLES OF THE THORAX. 
335 
is called ligamentum arcuatum internum (“ the inner arched ligament ”), and the 
other, ligamentum arcuatum externum (“ the outer arched ligament ”). Both give 
origin to muscular fasciculi. The largest part of the diaphragm arises from the 
inner surface of the last six costal cartilages, interdigitating with the transver- 
salis abdominis. Finally, the ensiform cartilage gives attachment to a small 
Fig. 399.—Diaphragm, viewed from below. (Testut.) 
INTERNAL INTERCOSTAL SEE N\ 
THROUGH ARTIFICIAL GAP IN 
EXTERNAL 
Fig. 400.—Intercostal muscles in right wall of thorax, (Testut.) 
band. The central tendon looks something like a trefoil, is very large, and to it 
the muscular bundles converge from the entire margin of the muscle. 
The aortic opening, already described, gives passage to the aorta, thoracic duct, 336 
THE MUSCLES. 
and large azygos vein. In front of this and higher up is an opening which trans- 
mits the oesophagus and pneumogastric nerves. Still higher and to the right is a 
third large aperture, devoted to the vena cava. Besides these great perforations 
are a number of small holes, which transmit nerves and vessels. 
The diaphragm is higher on the right side over the liver, and its upper surface 
is somewhat indented at the front central part, beneath the heart. Its nerve-sup- 
ply is mainly from the phrenics. 
When the diaphragm contracts, its arch is flattened, and thus the vertical 
capacity of the chest is increased. 
Intercostales Extern! (Fig. 400).—“ The external between-the-ribs muscles,” 
the muscles in the outer layer between the ribs. Their number corresponds to that 
of the intercostal spaces. They generally extend from the tuberosities of the 
ribs to the junction of the cartilages; the remainder of each space is occupied by 
a fibrous membrane. A similar membrane lines the muscles from the angles of 
the ribs backward. Each muscle arises from the lower border of a rib, runs 
downward and forward, and is inserted into the upper border of the rib next 
below. Their action lifts the ribs. Their nerves are the intercostal. 
Intercostales Intern! (Fig. 400).—“The internal between-the-ribs muscles.” 
Their number is that of the intercostal spaces. They occupy these spaces from 
the sternum to the angles of the ribs, and beyond these points fibrous membranes 
fill the spaces. Each muscle arises on the inner surface of a rib and its cartilage, 
just above its lower border, runs down- and backward, and is inserted into the 
inner surface of the rib just beneath. Their action is not agreed upon. The 
intercostal nerves supply them. 
Levatores Costarum (Fig. 391, L. C.).—“ The lifters of the ribs.” They are 
twelve in number. Each is inserted into the outer surface of a rib, between its 
tuberosity and angle, and arises from the tip of the transverse process of the ver- 
tebra immediately above. A few of those which are lowest in the series have 
each an insertion also into a rib beyond that proper to itself. The name of these 
muscles indicates their supposed action—elevation of the ribs ; but it is probable 
that, instead of this, they contribute to the extension and lateral flexion of the 
thoracic part of the vertebral column. They are supplied by the intercostal 
nerves. 
Triangularis Stern!.—“ The triangular muscle of the sternum.” Synonym, 
transversus thoracis anterior, u the front transverse muscle of the chest.” Situa- 
tion, on the inner side of the thoracic cage in front. Origin, the ensiform appen- 
dix, the lower part of the gladiolus, and the cartilages of the lower two or three 
true ribs. Direction, partly horizontal, partly oblique, partly nearly vertical. 
Insertion, the outer extremities of the costal cartilages from the second to the 
sixth. Action, depression of the ribs, to whose cartilages it is attached. Nerves, 
the intercostal. 
Subcostales,—“ The under-the-ribs muscles.” Synonym, infracostales, “ the 
beneath-the-ribs muscles.” These are small, inconstant muscles, found usually 
near the angles of the ribs, on the inner surface of these bones, and extending 
over two intercostal spaces. Their direction is down- and backward, and their 
nerves, the intercostal. Their action, which must be very insignificant, is not yet 
determined. 
THE MUSCLES OF THE NECK. 
A number of the muscles in the neck have already been considered in connec- 
tion with those of the back, the continuity of tissue or the close functional rela- 
tion between the former and the latter making this arrangement most convenient 
in all cases, and inevitable in others. 
There remain for study those muscles which are located in the ventral and 
lateral portions of the neck. MUSCLES OF THE FRONT AND SIDE OF THE NECK. 
337 
MUSCLES OF THE FRONT AND SIDE OF THE NECK. 
Superficial. 
Platysma. Sterno-cleido-mastoideus. 
Infrahyoid. 
Sterno-hyoideus. Sterno-thyroideus. 
Omo-hyoideus. Thyro-hyoideus. 
Suprahyoid. 
Digastricus. Mylo-hyoideus. 
Stylo-hyoideus. Genio-hyoideus. 
Deep Lateral. 
Scalenus anterior. Scalenus posterior. 
Scalenus medius. Rectus capitis lateralis. 
Prevertebral. 
Rectus capitis anterior major. Rectus capitis anterior minor. 
Longus colli. 
Platysma (Fig. 401).—“ The broad sheet muscle.” Synonym, platysma 
myoides, “ the muscle-like sheet.” Situation, in the front and side of the neck, 
and the lower part of the side of the face. Origin, the skin and areolar tissue 
covering the upper part of the pectoralis major, deltoideus, and trapezius, and, 
sometimes, the scapula and clavicle. Direction, upward and inward. Insertion, 
the outer surface of the mandible as far back as the masseter, and the muscular 
structures about the angle of the mouth and lower lip. Some fibres cross to the 
opposite side. Action : it draws the angle of the mouth and the lower lip down- 
and outward, and contracts the skin of the neck. Nerve, the facial. 
Sterno-cleido-mastoideus (Fig. 402).—“ The sternum-clavicle-mastoid-process 
muscle.” Synonym, sterno-mastoideus. Situation, in the side of the neck. 
Origin, the front of the manubrium and inner third of the clavicle. Direction, 
upward and backward. Insertion, the mastoid process of the temporal, and the 
outer half of the superior curved line of the occipital. An interval exists 
between the sternal and clavicular origins. The muscle divides the lateral area 
of the neck into two triangles. Action: it draws the head toward the shoulder, 
and rotates the face toward the opposite side. When the two muscles act, the 
head is extended. 
Sterno-hyoideus (Fig. 403).—“ The sternum-hyoid-bone muscle.” Situation, 
in the front of the neck. Origin, the back of the manubrium, and inner end of 
the clavicle. Direction, upward. Insertion, the body of the hyoid. Action, depres- 
sion of the hyoid. Nerve, the hypoglossal. 
Omo-hyoideus (Figs. 402, 403).—“ The shoulder-hyoid-bone muscle.” Situa- 
tion, the upper part of the shoulder and the front of the neck. Origin, the 
scapula, near the suprascapular notch. Direction, forward and inward to behind 
the sterno-cleido-mastoid, and then upward and a little inward. Insertion, the 
body of the hyoid. This is a slender, double-bellied muscle. The middle ten- 
don is held down by a loop of deep fascia, which is attached below to the sternum 
and cartilage of the first rib. Action, depression of the hyoid. Nerve, the 
hypoglossal. 
Sterno-thyroideus (Fig. 403).—“ The sternum-thyroid-cartilage muscle.” 
Situation, the front of the neck, behind the sterno-hyoid. Origin, the back of 
the manubrium, and cartilage of the first rib. Direction, upward. Insertion, the 
oblique line on the ala of the thyroid cartilage. Action, depression of thyroid 
cartilage. Nerve, the hypoglossal. THE MUSCLES. 
Thyro-hyoideus (Fig. 403).—“The thyroid-cartilage-hyoid-bone muscle,” 
Situation, in the front of the neck. Origin, the oblique line on the ala of the 
thyroid cartilage. Direction, upward. Insertion, the body and great cornu of 
the hyoid. Action, depression of the hyoid; by reversed action, elevation of the 
thyroid cartilage. Nerve, the hypoglossal. 
Digastricus (Figs. 402, 403).—“ The two-bellied muscle.” Situation, the 
uppermost part of the side of the neck. Origin, the digastric fossa of the tem- 
poral. Direction, forward, inward, and downward, then forward, downward, and 
slightly inward. Insertion, the mandible, at its lower border near the symphysis. 
The tendon between the bellies is held down to the hyoid bone by a fibrous loop 
and the stylo-hyoid muscle, and the change in direction is effected at this point. 
Fig. 401.—Superficial muscles of side of neck. (Testut.) 
Action, elevation of the hyoid, if the mandible is fixed; depression of the mandi- 
ble, if the hyoid is fixed. Nerves, the facial for the hind belly, the inferior maxil- 
lary division of the trifacial for the front belly. 
Stylo-hyoideus (Fig. 402).—“ The styloid-process-hyoid-bone muscle.” Situa- 
tion, in the uppermost part of the side of the neck, along the upper border of the 
hind belly of the digastricus. Origin, the root of the styloid process of the tem- 
poral. Direction, down- and forward. Insertion, the hyoid. Near its insertion 
it is perforated by the digastricus. Action : it lifts the hyoid, and pulls it back- 
ward and sidewise. Nerve, the facial. 
Mylo-hyoideus (Fig. 402).—“ The molar-teeth-hyoid-bone muscle,” so-called MUSCLES OF THE FBONT AND SIDE OF THE NECK. 
339 
from its attachments near the molars of the lower jaw and to the hyoid bone. 
Situation, in the floor of the month. Origin, the mylo-hyoid ridge of the 
mandible. Direction, down-, back-, and inward. Insertion, behind to the hyoid, 
in the middle line to its fellow opposite. Action: it lifts and advances the 
hyoid and the floor of the month. Nerve, the inferior maxillary division of the 
trifacial. 
Genio-hyoideus (Fig. 403).—“ The chin-hyoid-bone muscle.” Situation, in the 
floor of the month, above the mylo-hyoideus. Origin, the lower genial tubercle. 
Fig. 402.—Muscles in front and side of neck. (Testut.) 
Direction, backward and a little downward. Insertion, the body of the hyoid. 
Action : it lifts and advances the hyoid. Nerve, the hypoglossal. 
Scalenus Anterior (Fig. 404).—“The front scalene muscle”—i. e., triangular 
with unequal sides. Situation, deep in the side of the neck. Origin, the anterior 
tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical 
vertebras. Direction, down-, out-, and forward. Insertion, the tubercle on the 
upper surface of the first rib. Action, elevation of the first rib. Nerves, the 
neighboring cervical. 
Scalenus Medius (Fig. 404).—“ The middle scalene muscle.” Situation, deep 
in the side of the neck. Origin, the posterior tubercles of the transverse pro- 
cesses of all of the cervical vertebrae. Direction, down-, out-, and forward. 
Insertion, the upper surface of the first rib. Action, elevation of the first rib. 
Nerves, the neighboring cervical. 340 
THE MUSCLES. 
Scalenus Posterior (Fig. 404).—“ The hind scalene muscle.” Situation, deep 
in the side of the neck. Origin, the posterior tubercles of the transverse pro- 
cesses of the lower two or three cervical vertebrae. Direction, down-, out-, and 
forward. Insertion, the outer surface of the second rib. Action, elevation of the 
second rib. Nerves, the neighboring cervical. 
Rectus Capitis Lateralis (Fig. 404).—“ The side straight muscle of the head.” 
Situation, the side of the highest part of the neck. Origin, the transverse pro- 
cess of the atlas. Direction, upward. Insertion, the jugular process of the 
occipital. Action, tilting the head sidewise. Nerve, the first cervical. 
Rectus Capitis Anterior Major (Fig. 404).—“ The greater front straight mus- 
cle of the head.” Synonym, rectus capitis anticus major. Situation, in front 
of the upper cervical vertebrae. Origin, the anterior tubercles of the transverse 
processes of the third, fourth, fifth, and sixth cervical vertebrae. Direction, up- 
Fig. 403.—Infrahyoid and suprahyoid groups of muscles. (Testut.) 
and inward. Insertion, the basilar process of the occipital. Action, flexion of the 
head on the spine. Nerves, the neighboring cervical. 
Rectus Capitis Anterior Minor (Fig. 404).—u The smaller front straight mus- 
cle of the head.” Synonym, rectus capitis anticus minor. Situation, between 
the atlas and occipital bone in front. Origin, the front of the transverse process 
of the atlas. Direction, up- and inward. Insertion, the basilar process of the 
occipital. Action, flexion of the head. Nerve, the first cervical. THE MUSCLES OF THE HEAD. 
341 
Longus Colli (Fig. 404).—“ The long muscle of the neck.” Situation, in front 
of the cervical and upper thoracic vertebrae. Division, into three parts : the 
vertical or middle, the lower oblique, and the upper oblique. The vertical part 
arises from the bodies of the last two cervical and two or three thoracic vertebrae, 
and the transverse processes of the last three or four cervical, and is inserted 
into the bodies of the second, third, and fourth cervical. The lower oblique part 
arises from the bodies of the upper two or three thoracic vertebrae, and is inserted 
JNTERTRANS- 
VERSALIS 
Fig. 404—Deep lateral and prevertebral muscles of the neck. (Testut.) 
into the anterior tubercles of the transverse processes of the fifth and sixth 
cervical. The upper oblique part arises from the anterior tubercles of the trans- 
verse processes of the third, fourth, and fifth cervical vertebrae, and is inserted 
into the anterior tubercle of the atlas. Action, mostly, flexion of the neck ; also, 
rotation. Nerves, the neighboring cervical. 
THE MUSCLES OF THE HEAD. 
In the head are many muscles which are most conveniently treated of in con- 
nection with certain special organs, as the tongue, palate, pharynx, eye, and ear. 
In this place, therefore, there will be considered only the superficial muscles. 342 
THE MUSCLES. 
SUPERFICIAL MUSCLES OF THE HEAD. 
Muscles of Mastication 
Masseter. 
Pterygoideus interims. 
Pterygoideus externus. 
Temporalis. 
Muscles of Expression. 
Orbicularis oris. Levator anguli oris. 
Levator labii superioris alseque Risorius. 
nasi. Buccinator. 
1. Muscles Affecting the Orifice of the Mouth. 
Levator labii superioris proprius. 
Zygomaticus minor. 
Zygomaticus major. 
Depressor anguli oris. 
Depressor labii inferioris. 
Levator labii inferioris. 
2. Muscles of the Nose. 
Pyramidalis nasi. Levator labii superioris aleeque 
Compressor naris. nasi. 
Depressor alse nasi. 
3. Muscles of the Lids. 
Orbicularis palpebrarum. Tensor tarsi. 
Levator palpebrse. 
4. Muscles of the Forehead. 
Corrugator supercilii. Frontalis, 
5. Muscle of the Occiput. 
Occipitalis. 
The Muscles of Mastication. 
Masseter (Figs. 407, 402).—“ The chewing-muscle.” Situation, in the back 
part of the side of the face. It consists of two portions, the superficial and the 
deep, which blend at their insertion. The superficial portion arises from the 
lower margin of the anterior two-thirds of the zygoma, passes down- and back- 
ward, and is inserted on the outside of the lower half of the ramus of the man- 
dible. The deep portion arises from the entire inner surface and the hind third 
of the lower border of the zygoma, passes downward, and is inserted into the 
upper half of the ramus of the mandible. Action, elevation of the lower jaw. 
Nerve, the inferior maxillary division of the trifacial. 
Temporalis (Fig. 405).—“ The temple muscle.” Situation, in the temporal 
fossa. Origin, the entire temporal fossa, except the anterior wall. Direction, down- 
ward. Insertion, the coronoid process of the mandible. Action, elevation of 
the lower jaw, and, when this has been drawn forward, its retraction. Nerve, 
the inferior maxillary division of the trifacial. 
Pterygoideus Internus (Fig. 406).—“ The internal pterygoid muscle,” so-called 
from its position and origin. Synonym, the internal masseter. Situation, the 
inner side of the ramus of the mandible. Origin, the inner surface of the exter- 
nal pterygoid plate of the sphenoid, and the tuberosities of the palate and superior 
maxillary bones. Direction, down-, back-, and outward. Insertion, the inner 
side of the ramus of the mandible, between the angle and the dental foramen. 
Action, elevation of the lower jaw. When the jaw is closed, the muscle draws 
it forward. Nerve, the inferior maxillary division of the trifacial. 
Pterygoideus Externus (Fig. 406).—“ The external pterygoid muscle,” named 
from its position and origin. Situation, in the zygomatic fossa. Origin, by two SUPERFICIAL MUSCLES OF THE HEAD. 
343 
heads : the upper head, the zygomatic surface of the great wing of the sphenoid ; 
the lower head, the outer surface of the external pterygoid plate. Direction, out- 
and backward. Insertion, the neck of the mandible, and the interarticular fibro- 
Fig. 405.—Temporal and deep muscles about the mouth. (Testut.) 
cartilage of the temporo-mandibular joint. Action : it draws the condyle of the 
mandible and the interarticular cartilage forward and inward. Nerve, the infe- 
rior division of the trifacial. 
The Muscles of Expression. 
The muscles of expression are sometimes called “the mind muscles,” from the 
indications which they may afford of the mental state of the individual. The 
majority of them are small, often poorly defined, and so blended with each other 
and the skin that their dissection is frequently difficult and unsatisfactory. They 344 
THE MUSCLES. 
are all supplied by the facial nerve. It is helpful to group them according to 
their situation into those related to the orifice of the mouth, those of the nose, 
those of the eyelids, those of the forehead, and that of the occiput. Besides these 
are others, which, in a secondary though important way, contribute to expression. 
The muscles which move the eyes are very effective in betraying emotion, and 
the muscular tongue, usually concealed in the oral cavity, may, either with or 
without partial protrusion from its retreat, be made to convey as distinct an idea 
as can be given by articulate speech. Even the muscles of the pinna might, 
without unwarrantable stretch of terms, be included in this group, since they are 
Fig. 406.—Pterygoid muscles, viewed from behind, the back portion of the skull having been removed. 
(Testut.) 
the rudimentary hornologues of organs, which, in many lower animals, are strik- 
ingly useful in expressing various feelings. But the muscles of the orbit and of 
the external ear are treated more appropriately in connection with the organs of 
the special senses; and those of the tongue are best presented, in company with 
the palatal and pharyngeal, as parts of the alimentary system, just as the laryn- 
geal are discussed most conveniently with the respiratory system, and the peri- 
neal with the generative system. 
Muscles affecting the Orifice of the Mouth. 
Orbicularis oris. 
Levator labii superioris alseque 
nasi. 
Levator labii superioris proprius. 
Zygomaticus minor. 
Zygomaticus major. 
Levator anguli oris. 
Risorius. 
Buccinator. 
Depressor anguli oris. 
Depressor labii inferioris. 
Levator labii inferioris. SUPERFICIAL MUSCLES OF THE HEAD. 
345 
Orbicularis Oris (Fig, 407).—“ The orbicular muscle of the mouth ”—that is, 
encircling the oral orifice. Surrounding the opening of the mouth, and extending 
from the nose above to the chin below, is an elliptical muscle, which forms a great 
part of the bulk of the lips, and constitutes a sphincter to the aperture. It does 
not, however, consist of concentric bundles of fibres, but is made up very largely 
of prolongations from various muscles of the face, which converge to its margin. 
It is attached above to the partition between the nostrils and to the incisor fossse 
Fig. 407.—Superficial muscles of head and neck. (Testut.) 
of the upper jaw-bones, and below to the incisor fossse of the mandible. It is 
covered in front by skin, behind and on its free border by raucous membrane. 
The action of this muscle is to close the lips and press them against the teeth. It 
antagonizes all of the remaining members of this group, except the levator labii 
inferioris. 346 
THE MUSCLES. 
The nine following muscles arise from structures, principally osseous, in the 
face, converge to the margin of the orbicularis, and are either inserted into it or the 
skin covering it. Six are close to the surface, and three are more deeply situated. 
All of them by their action oppose that of the orbicularis, and in various direc- 
tions enlarge the opening of the mouth. 
Levator labii superioris alseque nasi (Fig. 407), “ the lifter of the upper lip and 
of the wing of the nose,” arises from the nasal process of the superior maxillary 
bone, passes downward and outward, and is inserted partly into the wing of the 
nose, partly into the orbicularis. Its name describes its action. 
Levator labii superioris proprius (Fig. 407), “ the proper lifter of the upper 
lip,” the last word of the name being used to emphasize the distinction between 
this and the preceding muscle, which does other than the special work of this. 
It arises just above the infra-orbital foramen and the neighboring part of the 
malar bone, runs downward and inward, and is inserted into the margin of the 
orbicularis and the skin of the lip. It raises the part of the lip near the median 
line. 
Zygomaticus minor (Fig. 407), “ the smaller zygomatic muscle.” The name 
implies attachment to the zygoma, but was unwisely given on account of its near- 
ness to a muscle which somewhat merits the title zygomatic. It arises from the 
front and lower part of the malar bone, and is inserted into the orbicularis and 
the skin, just outside of the levator labii superioris proprius. It raises and draws 
outward the upper lip. 
Zygomaticus major-(Fig. 407), “the larger zygomatic muscle,” arises from the 
malar near its zygomatic suture, passes downward and inward, and is inserted 
into the skin at the angle of the mouth. It draws the angle upward and outward. 
Levator anguli oris (Fig. 405), “ the lifter of the angle of the mouth,” arises 
below the infra-orbital foramen, passes downward, and is inserted into the 
orbicularis and the skin near the corner of the mouth. Its name implies its 
action. 
Kisorius (Figs. 401, 407).—The name means “the laughing muscle,” but it is 
not descriptive. The muscle extends from the fascia over the masseter to the 
skin and orbicularis at the angle of the mouth. It is regarded as a specialized 
part of the platysma. It draws the mouth outward horizontally, widening the 
cleft. 
Buccinator (Fig. 405), “ the trumpeter’s muscle,” arises from the back part of 
the outer surface of the alveolar processes of both jaw-bones, and from the 
ptery go-max illary ligament. Its different parts converge to the angle of the mouth, 
and there blend with the orbicularis. It pulls the angle outward, and compresses 
the contents of the vestibule of the mouth. If the cheek bulges with air, the 
buccinator presses it out, measurably regulating its expulsion, as in blowing a 
horn (hence the name) ; and it keeps the mass of food during mastication from 
escaping outward from the grasp of the molar teeth. 
Depressor Anguli Oris (Fig. 407).—“ The depressor of the angle of the mouth.” 
Synonym, triangularis menti, “ the triangular muscle of the chin.” It arises from 
the external oblique line of the mandible, passes upward, converging to the angle 
of the mouth, where it blends with the orbicularis. It pulls down the corner of 
the mouth. 
Depressor Labii Inferioris (Figs. 405, 407).—“The depressor of the lower lip.” 
Synonym, quadratus menti, “the square muscle of the chin.” It arises from the 
mandible, from near the symphysis to beyond the mental foramen, passes upward 
and inward, and merges with the orbicularis. It draws the lower lip downward 
and slightly outward. 
Levator Labii Inferioris.—“ The lifter of the lower lip.” Synonym, levator 
menti, “ the lifter of the chin.” It arises from the incisor fossa of the mandible, 
passes downward, and is inserted into the skin of the chin. It differs from the 
other muscles which act upon the oral aperture in not participating in the struct- 
ure of the lips or cheeks, and in not antagonizing the orbicularis; but, while its SUPERFICIAL MUSCLES OF THE HEAD. 
347 
force is primarily directed to the chin, which it elevates, its practical effect is to 
lift the lower lip, which is carried upward by the movement of the chin, and 
made to protrude. Thus, it assists the lower half of the orbicularis, helping' to 
close the opening and hold it tightly. 
In the play of the features which the muscles about the mouth produce they 
almost always act in pairs, and one pair rarely acts alone. This is illustrated in 
the display of the opposite emotions of mirth and grief. In the former the 
lifters of the angles and the zygomatics draw the corners upward and outward, 
the risorii widen the aperture still more, and the lifters of the upper lip pull it 
upward. In the latter the depressors of the angles drag downward the corners 
of the mouth, the risorii widen the slit, and the lifters of the upper lip draw it 
upward. In both of these cases it will be observed that the transverse crevice 
of the mouth is widened, the upper lips are elevated, uncovering the front upper 
teeth, and the angles of the mouth are drawn outward. By this last procedure 
the cheeks are pulled upward, and a bulging forward of the structures under the 
orbits and a partial closure of the lower lids arc thus produced. The main differ- 
ence, then, between the facial manifestation of joy and that of sorrow consists in 
the up-and-down movements of the angles of the mouth. Ihe risorius does not 
deserve the name of the laughing muscle as well as does the zygomaticus major. 
Pyramidalis nasi. Levator labii superioris alseque 
Compressor naris. . nasi. 
Depressor alee nasi. 
Muscles of the Nose, 
Pyramidalis nasi (Fig. 407), “ the pyramidal muscle of the nose,” arises at the 
lower border of the nasal bone, passes upward, is inserted into the skin between 
the brows, and by its action draws this skin downward, producing a horizontal 
wrinkle. The fibres often seem to be continuous with the median portion of the 
frontalis. 
Compressor Naris (Figs. 405, 407). uI he compressor of the nostril.” Syno- 
nyms, compressor narium, “the compressor of the nostrils;” compressor nasi, 
“ the compressor of the nose.” It arises from the nasal bone and adjacent carti- 
lage near the mid-line, passes downward and backward, and is inserted partly 
into the superior maxillary near the nasal opening, and partly into the levator 
labii superioris alseque nasi. It pulls inward the muscle to which it is attached, 
thus wrinkling the nose vertically; and it slightly compresses the nose. 
Levator labii superioris alaeque nasi has been described on page 346. 
Depressor alae nasi (Fig. 405), “ the depressor of the wing of the nose,” arises 
from the incisor fossa of the superior maxillary bone, passes upward and outward, 
and is inserted into the cartilage of the wing of the nose and into the septum. 
It draws the wing of the nose downward and inward. 
Besides these muscles there £irc sometimes found two minute <md indistinct 
bundles, which descend to the margin of the ala from the cartilages just above, 
and have been dignified by names which are descriptive of the slight action of 
these structures. 'They are levator proprius alee nasi anterior, “ the front proper 
lifter of the wing of the nose,” otherwise called dilatator naris anterior, “ the front 
widener of the nostril; ” and levator proprius alee nasi posterior, “ the hind proper 
lifter of the wing of the nose,” sometimes known as dilatator naris posterior, “ the 
hind widener of the nostril.” Finally, running from the cartilage of the wing 
to the skin at the tip of the nose is the inconstant and insignificant compressor 
narium minor, “the smaller compressor of the nostrils. 
Muscles of the Forehead. 
Corrngator supercilii. Frontalis. 
Corrugator supercilii, “ the wrinkler of the brow/’ arises from the superciliary 348 
THE MUSCLES. 
ridge, passes outward and upward, and is inserted into the skin above the middle 
of the upper margin of the orbit. It draws the skin toward the middle line, 
causing vertical wrinkles in the central lower part of the forehead. 
From the brows to the superior curved lines of the occipital bone the vault 
of the skull is covered by a musculo-membranous structure, which is by some 
anatomists regarded as a digastric muscle, the ocdpito-frontalis; but the contrac- 
tile portions will here be described as separate organs, one as a muscle of the fore- 
head, the other as a muscle of the occiput; and the intervening membrane as the 
epicranial aponeurosis. It will be well to consider the last before the others. 
The epicranial aponeurosis is a wide, firm, fibrous sheet, running antero-pos- 
teriorly over the summit of the cranium, attached before to the frontalis muscle, 
behind to the occipitalis and the occipital protuberance. It is thickest near the 
middle, and very thin at the sides. It is closely adherent to the skin which covers 
it, but only loosely to the pericranium over which it lies. 
Frontalis (Fig. 407), “ the forehead muscle,” arises from the anterior end of 
the epicranial aponeurosis, passes downward, and is inserted into the skin and 
muscles from the root of the nose to the outer end of the eyebrow. It elevates 
the brows, causing transverse wrinkling of the forehead. 
Muscle of the Occiput. 
Occipitalis (Fig. 407), “the occipital muscle,” is situated at the back of the 
head. It arises from the outer two-thirds of the superior curved line of the 
occipital bone and the mastoid portion of the temporal, passes upward, and is 
inserted into the epicranial aponeurosis. It acts in direct line with the frontalis, 
and emphasizes its action—that is, the transverse wrinkles of the forehead caused 
by the frontalis are made more conspicuous when the occipitalis acts at the same 
time. Alternate contraction of these two muscles in some persons produces a 
fore-and-aft movement of the scalp. The occipitalis is a weak muscle, but what 
force it has is exerted in the direction of expression. THE FASCIiE. 
F. H. GERBISH. 
THE word fascia, meaning literally a “ band ” or “ bandage,” is applied to 
fibrous, membranous expansions of greater or less density, which are wrapped 
around various organs, most conspicuously muscles, and serve to keep them in 
definite and intimate relation with one another. The term is also used to desig- 
nate certain strong, fibrous sheets which are stretched between bony parts. 
Fasciae are conventionally divided into two groups or varieties—the superficial 
and the deep. These terms, however, convey very little useful information about 
the organs to which they are applied. Some members of each group are struct- 
urally indistinguishable from typical specimens of the other. The ground of 
distinction upon which the names are based is their situation ; but one variety 
will frequently be found to shade olf by almost imperceptible gradations into the 
other, even on the same plane. In their typical forms, however, the superficial 
fascia is a loose, extensible structure; the deep fascia is firm, strong, and 
inextensible. 
THE SUPERFICIAL FASCIA. 
Immediately beneath the skin in almost every part of the body is a continuous 
layer of areolar tissue, which is called the superficial fascia. In most cases it 
differs in no essential respect from the areolar tissue in other localities : it contains 
fat-cells, it furnishes a suitable medium for the lodgement of vessels and nerves 
on their way to and from various organs, and it both connects and separates 
structures between which it is interposed always the skin on one surface, and 
usually the deep fascia on the other. It varies greatly in thickness, in some 
places being extremely thin and delicate, and in others very thick and large- 
meshed, the belly and buttock furnishing striking illustrations of the latter con- 
dition. Though it usually permits free movement of the skin on the subjacent 
parts, there are notable exceptions to the rule, as in the palm and sole, where it 
contains strong bands which lash down the skin tightly, and almost deprive it of 
mobility. 
The superficial fascia is in some parts peculiarly modified; in the scrotum it 
contains no fat-cells, has mingled with its fibrous tissues a quantity of unstriped 
muscle, and is known as the dartos; in certain places it becomes condensed into 
a fibrous film, as in the cribriform fascia, which is stretched across the saphenous 
opening. Sometimes it is directly continuous with the other (deep) fascia, the 
latter thinning out and gradually losing itself in the areolar tissue. Occasionally 
the superficial adheres to the deep along a line of considerable length, as on the 
thigh near the inguinal ligament, and thus a subcutaneous accumulation of fluid is 
steered off in a special direction, as would not be the case but for this peculiarity. 
Two distinct layers are found in certain situations, as on the front of the abdo- 
men, and they may differ considerably in structure, the more superficial generally 
containing more fat-cells, the deeper being more condensed. The veins which 
349 350 
THE FASCEE. 
course through this tissue are in some situations large and conspicuous, as on the 
dorsum of the hand and foot. Other organs are located in it, of which the most 
notable is the mammary gland. 
The occasions for calling this structure other than subcutaneous areolar tissue 
are very infrequent; and, as the name “ fascia,” unless limited by an adjective, is 
usually employed in surgical parlance to designate the deep fascia, it wall be thus 
used in the remainder of this chapter, unless specific exception is made. 
THE DEEP FASCIAE. 
The typical deep fasciae are close sheets of fibrous tissue, in which the white 
variety exists in an almost unadulterated form. On account of this histological 
composition these fasciae are pearly white, flexible, strong, and inelastic. Their 
structure and physical qualities immediately bring to mind the characteristics of 
ligaments and tendons, which have identical structure; and the suggestion is 
especially apt for the reason that some fasciae are really interosseous ligaments, 
and a number are properly to be regarded as tendons. Moreover, the employ- 
ment of the word “ fascia” is ofttimes arbitrary, as, for example, in the case of 
the transversalis abdominis muscle, whose tendon of origin is almost always 
described as a layer of the lumbar fascia, and whose tendon of insertion is con- 
ventionally dubbed an aponeurosis, although in both situations the tendons are 
sheet-like expansions, which serve for the ensheathing of muscles. 
In this connection it is interesting and useful for the student to observe anew 
the continuity of the fibrous membranes—ligaments, tendons, and fasciae blending 
with periosteum, tendons and fasciae serving as ligaments, tendons losing them- 
selves in fasciae, tendons of some muscles acting as fasciae for other muscles, and 
so on. 
THE FASCDE OF THE HEAD. 
A structure which may fairly be included in this group is the epicranial apo- 
neurosis, which has already been described in connection with the muscles of the 
region (page 348). 
The Temporal Fascia. 
The temporal fascia has its superior attachment on the upper temporal ridge, 
its inferior on both borders of the zygoma, splitting into two layers just before 
reaching this arch. It encloses the temporal muscle, and is partially covered by 
the epicranial aponeurosis, the orbicularis palpebrarum, attrahens aurem, and 
attolens aurem. 
The Masseteric Fascia. 
The masseteric fascia is directly continuous with the cervical fascia. It 
covers the masseter muscle, and ends above at the lower border of the zygoma. 
In front it is in part attached to the coronoid process and in part blends with the 
buccinator fascia. Traced backward it is found to cover the parotid gland, and 
this portion is often called the parotid fascia. From the hind part of the last 
named a fibrous band is given off, connecting the angle of the lower jaw-bone 
with the styloid process of the temporal, the stylo-mandibular ligament. (See 
outer cervical fascia.) 
The Buccinator Fascia. 
The buccinator fascia covers the buccinator muscle. Above and below it is 
attached to the alveolar processes of the jaw-bones, behind is continuous with the 
masseteric fascia, and in front gradually thins out into areolar tissue. THE CERVICAL FASCIA. 
351 
THE CERVICAL FASCIA 
The deep fascia of the neck is conveniently divided for description into three 
portions : the outer or superficial, the middle, and the inner or deep, all of which, 
however, are continuous (1 ig* 408). 
The Outer Cervical Fascia, 
The outer 'portion forms a firm investment for the organs of the neck, its 
shape being suggestive of a hollow cylinder. Its upper limit extends from the 
-MIDDLE CERVICAL 
FASCIA 
-OUTER CERVICAL 
FASCIA 
INNER CERVICAL FASCIA- 
CESOPHAGUS- 
. , , . a horizontal section of the neck at the level of the sixth cervical 
Pig. 408.—The cervical fascia, as seen m a mu 
vertebra. (Testut.) 
external occipital protuberance to the lower part of the symphysis of the mandible 
attaching itself to the series of skeletal prominences most nearly coinciding with 
a line drawn around the head ant 111 
seating these points. Below it is fiih cnec o 
the sternum, clavicle, acromion, am scapu ar 
spine, beyond the last named losing isc in 
the fascia of the back. Thus ,t includes 
especially in its lower parts, somew ia mor 
than the strict anatomical neck, it is at- 
tached behind to the ligamentnm nuchse, and 
in front it is continuous across the mid 
line. In its course around the side o 
neck it splits twice, first embracing ie 
trapezius, and then the sterno-mastoidform- 
ing strong sheaths for these muscles. lc 
from below upward in the region m ion c> 
the sterno-mastoid, it is found to be a ac 
to the hyoid, from which it runs to its upper 
: i A** fhc mandible 
MYLO-HYOID 
PFCHAMBER OFV 
SUBMAX. SALI- 
VARY GLAND 
'MANDIBLE 
HYOID 
Fig. 109.—The outer cervical fascia between 
the hyoid and mandible. (Testut.) 
limit on the lower noraei ux my “ . 
lends to9the 352 
THE FASCIAE. 
under surface of the mylo-hyoid muscle. Thus it may be said that the fascia 
splits at the hyoid, and encloses between its two lamellae a space, which is triangu- 
lar in vertical section, and forms a chamber occupied by the submaxillary salivary 
gland. Below and in the middle line in front the fascia separates into two layers, 
one going to the anterior, the other to the posterior border of the top of the manu- 
brium (Fig. 410). From the front of the portion of the fascia which forms a 
sheath for the sterno-mastoid, and where it is continuous with the masseteric 
fascia, a prolongation is given off forward and inward, is attached to the angle 
of the lower jaw, passes behind the parotid gland, and ends by insertion into the 
styloid process of the temporal, forming thus the stylo-mandibular ligament. 
The Middle Cervical Fascia. 
The middle portion of the cervical fascia—that is, the portion between the 
superficial and deep layers—lies close behind the front part of the outer layer 
(Figs. 410, 411), arching between the omo-hyoids of the two sides, forming a 
sheath for each of them, and extends vertically from the hyoid to the sternum, 
and laterally from one scapula to the 
other, its side borders corresponding 
with the omo-hyoids. The part which 
ensheathes these muscles sends from each 
a band down to the sternum and the 
cartilage of the first rib. From the 
point where the fascia is attached to the 
middle line of the sternum a prolonga- 
LEFT BRACHIO- 
'CEPHALIC VEIN 
CLAVICLE— 
.TO VERTEBRAL 
COLUMN 
TO PERICARDIUM 
Fig. 410.—The cervical fascia between the hyoid 
and sternum. (Testut.) 
Fig. 411.—The cervical fascia in the clavicular 
region. (Testut.) 
tion of it encircles the left brachio-cephalic vein (Fig. 410), and then passes 
down into the thorax and blends with the pericardium. On each side it is 
fastened to the clavicle, gives off expansions which encase the subclavian vein, 
and then are attached to the first rib and become continuous with the neighboring 
fasciae (Fig. 411). A continuation of the middle layer enters into the formation 
of the sheath ,of the axillary vessels and nerves. Prolongations also are sent 
inward and furnish the neck muscles with sheaths ; for the most part, however, 
these processes have not the firmness of the main layer, but are areolar in 
character. 
The Inner Cervical Fascia. 
The inner or deep layer of the cervical fascia, known also as the prevertebral, 
is continuous with the middle portion at the sheaths of the carotid arteries and 
internal jugular veins. It is attached above to the basilar process of the occipital 
bone, at the sides to the transverse processes of the cervical vertebrae, and below THORACIC FASCIA. 
353 
gradually thins out and merges into the areolar tissue of the posterior medias- 
tinum. In front of it are the pharynx and oesophagus, behind it the prevertebral 
muscles. 
Peculiar interest attaches to these different portions of the cervical fascia on 
account of their influence upon the direction which accumulations of fluid will 
take when occurring in this region (Fig. 412). Fluid in front of the outer layer 
HYOID— 
OUTER CERVICAL FASCIA ' 
SKIN - 
“DEEP CERVICAL 
FASCIA 
MIDDLE CERVICAL FASCIA- 
STERNUM- 
Fig. 412.—The cervical fascia as seen in sagittal section. (Testut.) 
is confined to the subcutaneous region; between the outer and middle layers is 
kept from descending by the sternum; between the middle and inner or pre- 
vertebral is guided into the pharynx and oesophagus, or possibly into the larynx ; 
and behind the last layer may be steered into the mediastinum. 
THORACIC FASCIA. 
This name, though often limited to the fascia of the pectoralis major, is much 
more fittingly applied to the entire series of fasciae of the autero-lateral region of 
the chest, and is here employed in this sense. 
The Pectoral Fascia. 
The pectoral fascia (Fig. 413), thin and weak, covers the pectoralis major, 
and its attachments coincide with the margins of origin of this muscle. It turns 
around the lower border of the muscle and spreads upward over the hind surface. 
At the line where it makes the bend it is continuous with the true axillary fascia, 
a thick, strong membrane, which crosses the base of the armpit, describing an 
arch in its course, unites with the fascia which encases the latissimus, and through 354 
THE FASCIAE. 
this last becomes attached to the spines of the thoracic vertebrae. At its outer 
side the axillary fascia merges with the sheath of the vessels and is continuous 
with the fascia of the arm; it is 
also connected with the fascia of 
the shoulder. 
SUBCLAVIUS 
C LAV I - PE CTO 
The Clavi-coraco-axillary Fascia. 
) PECTORAL 
J FASCIA 
This is a quadrilateral sheet 
which runs vertically from the 
clavicle and coracoid process above 
to the fascia of the armpit below, and 
lies just behind the pectoralis ma- 
jor (Fig. 414). It has a double 
attachment to the clavicle, one 
layer being in front, the other 
behind, and between them is lodged 
the subclavius, to which they furnish 
a strong sheath. The hind layer 
is continuous with the sheath of 
the axillary vessels, which extends 
SHEATH OF PEC- 
TORALIS MINOR 
PECTORALIS MINOR 
LATISSI MUS 
FASCIA OF 
LATISSIMUS 
SUSPENSORY LIGA- 
' MENT OF AXILLA 
AXILLARY FASCIAi*^ 
Fig. 413.—The pectoral and axillary fasciae, seen in 
sagittal section. (Testut.) 
downward from the cervical fascia. In the middle of its course the clavi-coraco- 
axillary fascia splits and closely embraces the pectoralis minor between its layers. 
From the lower (outer) border of this muscle it is again single, and, extending 
outward, unites with the sheath of the coraco-brachialis. The portion of the 
fascia above the pectoralis minor, being 
fastened internally to the first rib, is 
named the costo-coracoid membrane 
and clavi-pectoral fascia. The upper- 
most part of it is the strongest, and is 
called the costo-coracoid. ligament. The 
portion of the fascia between the pecto- 
ralis minor and the coraco-brachialis is 
triangular, its apex being at the cora- 
coid process, its base at the lowest part 
of the axilla. It serves to preserve 
the hollow of the armpit, and has, con- 
sequently, been named the suspensory 
ligament of the axilla. 
The Intercostal Fascise. 
The external intercostal muscles 
are covered on their outer surfaces and 
the internal intercostal on their inner 
surfaces by the fibrous membranes, 
which are called respectively the ex- 
ternal and internal intercostcd fascice. 
They are most pronounced in the por- 
tions of the spaces between the ribs 
which are not occupied by both va- 
Fig. 414.—The clavi-coraco-axillary fascia of right 
side, front view. (Testut.) 
rieties of these muscles. A thinner fascia separates the muscles of each space 
THE FASCLE OF THE SHOULDER. 
In the region of the shoulder are the subscapular, supraspinous, infraspinous, 
and deltoid fascise (Fig. 415). THE FASCIA OF THE FOREARM. 
355 
The Subscapular Fascia. 
The subscapular fascia is attached to the margins of the fossa of the same 
DELTOID 
FASCIA 
infraspinous 
FASCIA 
DELTOID FASCIA— 
AXILLARY BORDER. 
OF SCAPULA 
VERTEBRAL BORDER 
OF SCAPULA 
name, and forms a covering for the suhsoapularis muscle. 
Fig 415 —The fascia; of the shoulder, seen in horizontal section. (Testut.) 
The Supraspinous Fascia. 
The supraspinous fascia, dense and strong, is attached to the borders of the 
fossa above the spine of the scapula, thus completing the osseo-fibrous chamber, 
which is filled by the supraspinatus muscle. 
The infraspinous fascia is like the last named in structure and similar in 
arrangement being attached at the edges of the lower fossa on the dorsum of the 
scanula thus forming with the bone a cavity, which is completely occupied by the 
infraspinatus Where this muscle is overlapped by the hind border of the deltoid 
the fascia splits, one layer passing upon the latter muscle and forming part of the 
deltoid fascia, the other going in front of the deltoid and ending by fusion with 
the fibrous structure of the shoulder-joint. 
The Infraspinous Fascia. 
The Deltoid Fascia 
The deltoid fascia covers in the deltoid muscle It is continuous behind with 
.r. if*•_ ;n front with the pectoral. It is fastened above to the 
boneT from'which muscle takes origin, and is continuous below with the fascia 
of the arm. 
the fascia of the arm. 
The brachial fama is continuous above with the pectoral and axillary fasche, 
as well as with that of the shoulder, and below with that of the forearm. It is 
, f, i +iip humerus and the olecranon process. It not only 
enwraps the the brachial region, but from its inner surface sends septa 
,‘p ~ ‘T, <m,,ter part of these partitions are merely areolar, but two 
between them The greater- par of then/;s attached t0 the 
are sti ong ant ngi , . .. . „roove the outer condylar ridge, and the intervening 
outer border situated on thelnner side-thns bein| 
formed thetrfaW and internal intermuscular septa,which divide the muscles into 
an anterior and a posterior set. 
The /_tllnCdnti Itt” Sd 
of the ulna. From its inner surface many septa are given 
THE FASCIA OF THE FOREARM. 356 
THE FASCIAE. 
off and extend between the muscles. For the most part these are areolar; but 
near the elbow, where groups of muscles arise from the condyles, the fibrous 
partitions are well marked. Between the first and second layers of the flexor 
muscles is stretched a thin layer of fascia, and a similar one is found between 
the superficial and deep groups of extensors. The fascia is much thicker behind 
than in front. At the lower end of the forearm the fascia terminates in the 
so-called annular ligaments, anterior and posterior. The name implies a ring-like 
structure ; but each extends only half-way round the limb, and, while the posterior 
is almost entirely within the limits of the forearm, the anterior is wholly within 
the boundaries of the hand. 
The Posterior Annular Ligament. 
The posterior annular ligament (Fig. 417) is chiefly composed of transverse 
bundles of fibres constituting a broad and strong band, which has bony attach- 
ments on the inner side to the styloid process of the ulna, the cuneiform and the 
pisiform, on the outer side to the lower end of the external border of the radius, 
and between these extremities to the vertical ridges on the back of the radius. 
In this way are formed six osseo-fibrous passages, lined with synovial membrane, 
and occupied by the tendons of the extensor muscles of the forearm which are 
inserted in the hand. 
THE FASCIAE OF THE HAND. 
In the hand are the anterior annular ligament, the palmar fascia, the inter- 
osseous fasciae, the superficial transverse ligament, the dorsal fascia, and the 
sheaths of the tendons of the digital muscles. 
The Anterior Annular Ligament. 
The anterior annular ligament runs transversely across the front of the carpus 
from the scaphoid and trapezium on the outer side to the pisiform and unciform 
on the inner, thus converting the groove of the carpus into a tubular passage, 
through which run the flexors of the digits. It is continuous above with the 
forearm fascia, and below with the palmar fascia. 
The Palmar Fascia. 
The palmar fascia is divided into three parts, a middle and two lateral. Of 
ihese the middle is the most important, and often no other part is intended when 
the term “ palmar fascia” is employed. 
The middle palmar fascia, is thick and strong, and seems to be in great part 
an expansion of the palmaris longus, though there appears to be no lack of the 
fascia in cases where the muscle is absent. Other portions originate from the 
anterior annular ligament. The fascia spreads out in fan-shape as it descends, is 
firmly adherent to the skin, and is inserted into the bases of the four fingers by a 
division for each. From these divisions slips are sent to the skin, the anterior 
metacarpo-phalangeal ligament, the sides of the neighboring metacarpal bones, and 
the digital sheaths, which will presently be described. From the lateral borders 
of the fascia a partition passes backward to the interosseous fascia, and in this 
way is formed a canal in which are lodged the tendons which traverse the palm. 
The lateral portions of the palmar fascia are thin, cover the thenar and hypoth- 
enar groups of muscles, and, extending around the borders of the hand, become 
continuous with the dorsal fascia. 
The anterior interosseous fascia is a thin layer which lies in front of the inter- 
osseous muscles, and is attached to the anterior ridges of the metacarpal bones. THE FASCIAE OF THE HAND. 
357 
In the interdigital commissures is a thin band, which extends from the index 
to the little linger, and forms the basis of the webs. It is called the superficial 
transverse ligament. 
The Dorsal Fascia of the Hand. 
This is a thin layer, continuous on each side with the lateral parts of the pal- 
mar fascia, above with the fascia of the forearm, and below with the sheaths 
of the extensor tendons. Between the metacarpal bones are stretched delicate 
fascise, which cover the dorsal interosseous muscles. 
On the palmar aspect of the digits each flexor tendon runs in a tubular canal, 
made by the concaved phalangeal surfaces and strong fibrous bands, which arch 
Fascial Sheaths of Tendons in the Hand. 
over these from the lateral margins 
of the bones. The bands are called 
vaginal ligaments, because they help to 
form the sheath {vagina) of the ten- 
don. They are very dense opposite 
the shaft of the phalanx, much thinner 
opposite the joints. Each of the 
canals is provided with a vaginal 
synovial membrane (Fig. 416), Those 
of the index, middle, and ring fingers 
are independent, cylindrical sheaths, 
covering the length of two phalanges ; 
that of the thumb, also, is separate, and 
extends from about two inches above 
the radiocarpal joints to the inter- 
phalangeal articulation ; and that of 
the little finger, starting a trifle higher 
in the forearm, reaches to the distal 
end of the second phalanx, and in- 
cludes also the flexor tendons of the 
other fingers as far as half-way down 
the palm. 
On the dorsal aspect of the hand 
a different arrangement obtains (Fig. 
417). The tendons of the digital ex- 
tensors spread out upon the back of 
the first and second phalanges and 
blend at the sides with the lateral 
MEDIAN NERVE 
I 
LONG FLEXOR OF / 
THE THUMB "j 
. LONG FLEXORS 
OF THE FINGERS 
Fig. 416.—Synovial membranes of tendons in the 
palm, artificially distended. (Testut.) 
ligaments of the joints from the meta- . 
carpo-phalangeal down, themselves acting as posterior ligaments. As has already 
been said, the posterior annular ligament forms with tne hind surface of the 
adjacent bones of the forearm a series of tubular canals, through which extensor 
tendons pass. These channels are provided with vaginal synovial membranes, 
which extend above and below the limits of the ligament. They contain tendons 
as follows : the first—that on the radial border—the extensor ossis metacarpi 
nolbVic; and the extensor brevis pollicis; the second, the extensores carpi radiales 
fongm?8 and brevisjthe third, the extensor longus pollicis ; the fourth, the exten- 
sor'communis digitorum and the extensor mdicis ; the fifth, the extensor minimi 
digit!; and the sixth—that on the ulnar border—the extensor carpi ulnaris. 358 
THE FASCIAE. 
THE FASCLE OF THE BACK. 
The vertebral fascia is an extension downward of the back part of the outer 
layer of the cervical fascia. It stretches from the spinous processes of the thoracic 
vertebrae to the angles of the ribs, covering in the deep vertical muscles of the 
The Vertebral Fascia. 
EXTENSOR COMMU- 
NIS DIGITORU M 
EXTENSOR MINIMI. 
EXTENSOR OSSIS 
METACARPI POLLICIS 
■EXTENSOR BREVIS POLLICIS 
■EXTENSOR LONGUS POLLICIS 
DIGITI 
EXTENSOR CARPI. 
ULNARIS 
EXTENSOR CARPI 
■RADIALIS BREVIS 
.EXTENSOR CARPI 
RADIALIS LONGUS 
ABDUCTOR 
INDICIS 
Fig. 417.—Synovial membranes of tendons in the dorsum of the forearm and hand, artificially distended. 
(Testut.) 
back, passing in front of the serratus posterior superior, and becoming continuous 
below with the lumbar fascia. 
The Lumbar Fascia. 
The lumbar fascia (Fig. 418) is, in reality, rather a combination of tendons 
than a true fascia of investment, although it serves also in the latter capacity. The 
latissimus, serratus posterior inferior, obliquus internus abdominis, and trans- 
versalis abdominis all participate in its formation. Regarded as a fascia, it springs 
from the vertebral column in three layers, the outer or posterior, the middle, and 
the inner or anterior. The outer layer begins at the tips of the spinous processes of 
the lumbar and sacral vertebrae, forming a direct downward continuation of the 
vertebral fascia. It is attached above to the last rib, and below to the hind third 
of the outer lip of the iliac crest and the ilio-lumbar ligament. The middle layer 
starts from the free ends of the transverse processes of the lumbar vertebrae; and 
the inner layer arises from the front of the bases of the same processes. The 
outer and middle unite at the outer edge of the erector spinae, which occupies the 
space between them ; and this double layer is joined by the inner a little farther 
away from the middle line, the enclosure thus bounded being filled by the quadratus 
lumborum. The fascia resulting from the combination of the three layers gives THE FASCIAE OF THE ABDOMINAL CA VITY. 
359 
origin to the transversalis abdominis ; the obliquus internus abdominis is inserted 
into a secondary lamella, which splits off' from the outer layer; and the latissimus 
and serratus posterior inferior arise from still another lamina, which separates 
from the main fascia nearer the median line. 
RECTUS 
■EXTERNAL OBLIQUE 
INTERNAL OBLIQUE 
TRANSVERSALIS 
-PERITONEUM 
PSOAS 
TRANSVERSA- 
LIS FASCIA— 
. QUADRATUS 
k LUM BO RU M 
LATISSI MUS 
ERECTOR SPIN^E 
F no _Qemi(iiaoTammatic horizontal section of trunk to show the lumbar fascia and the tendons of the 
lateral abdominal muscles. The upper figure shows the complete sheathing of the rectus in its superior por- 
tions; tire lower shows the arrangement in its inferior fourth. (Testut.) 
The front portions of the abdominal wall are largely made up of the tendons 
of insertion of the external oblique, internal oblique, and transversalis muscles, 
and these tendons are fasciae in the same sense that the different tendons are, which 
constitute the lumbar fascia; but they are rarely mentioned other than as apo- 
neuroses of insertion—a term which implies their tendinous character. 
THE FASCIiE OF THE ABDOMINAL CAVITY. 
The abdominal cavity is everywhere lined with a serous membrane, the peri- 
toneum 1 Between this, which furnishes the free surface of the cavity, and the 
muscular portion of the abdominal walls is interposed a delicate membrane, which, 
in the greater part of the abdomen proper, is known as the transversalis fascia, on 
account of its intimate connection with the great muscle against whose inner sur- 
pir>p p ii(S .11Ki in the back part of the abdomen proper and in the pelvis, is (jailed 
the iliac 'fascia, because the iliac,is is one of the great muscles with which it is in 
close relation, the other being the psoas. Each of these fascue is somewhat pro- 
longed beyond the abdominal cavity, as will presently be detailed. 
The Transversalis Fascia. 
The transversalis fascia is thickest at the groin, gradually becomes thinner as 
~ . , t 'a o'vtri ic nothing-but areolar tissue where it lines the under side 
it is traced upward, and is noumig y > 
p,, i-i „ jf attached to the inner border of the iliac crest, the outer 
hllf of Pomwt’s ligament, the spine of the pubic bone, and the ilio-pectineal line. 
Beneath Poupart’s ligament, a little to the inner side of its middle, the great ves- 
sels of the thigh, the femoral artery and vein, are found, the vein nearer the 
median line of the body. In front of these vessels tins fascia is prolonged 
' . ,i , • _ r,nrf nf their common sheath (the femoral or crural sheath), 
forming the ayVl°ue contributed by the iliac fascia. As the transversalis 
fiiscia°eseapes from the abdomen at tiiis point, it is strengthened by a band, which 360 
THE FASCIHJ. 
curves over the vessels, and is called the deep crural arch. The inner portion of 
this arch is the part of the fascia which is attached to the os pubis and ilio- 
pectineal line. Between the femoral vein and Gimbernat’s ligament is a little 
gap, the femoral ring, through which hernia is most liable to occur in females, 
this being the weakest spot in the inguinal region of the members of this sex. 
It is the abdominal opening of the femoral or crural canal, and is occupied by a 
lymph-node and some fat. About half-an-inch above the middle of the inguinal 
(Poupart’s) ligament is an oval opening in the transversalis fascia, called the inter- 
nal abdominal ring. It is the beginning of the inguinal canal, the other end of 
which is in the tendon of the external oblique muscle, just above the crest of the 
pubic bone. Through this canal passes the spermatic cord in the male and the 
round ligament of the uterus in the female. In each case the transversalis fascia 
is extended upon the structure contained in the canal, forming a covering which 
from its funnel-shape is called the infundibuliform fascia. 
The Iliac Fascia. 
The iliac fascia lies upon the iliacus and psoas muscles, which, as has been 
said, are intimately connected. The portion which covers the psoas is attached to 
the vertebral column coextensively with the front origin of the muscle, and also 
to the upper part of the sacrum. From this mesial origin it runs outward, its 
upper part joining the inner (anterior) layer of the lumbar fascia, its lower part 
blending with the fascia over the iliacus. Its upper end is attached to the liga- 
mentum arcuatum internum. The portion of the fascia which invests the iliacus 
stretches from the inner margin of the iliac crest to the iliac part of the ilio- 
pectineal line, and is also attached to the outer half of the inguinal (Poupart’s) 
ligament. It accompanies the united muscles out of the pelvis into the thigh, 
and, running behind the femoral artery and vein, furnishes the posterior part of 
the sheath of these vessels, the front part of which is derived from the trans- 
versalis fascia. It finally becomes continuous with the pubic portion of the fascia 
of the thigh, at the line of fusion of the two a partition being given otf between 
the psoas and pectineus to the ilio-pectineal eminence and the capsular ligament 
of the hip. 
THE PELVIC FASCIA. 
In direct downward continuation of the transversalis and iliac fascise, which 
belong to the abdomen proper, is the pelvic fascia, which, as the name implies, 
lines that portion of the belly-cavity which is known as the true pelvis. 
Besides the osseous and ligamentous structures presenting surfaces in the pel- 
vic cavity, there are the internal obturator muscles at the sides, the pyriformis 
muscles behind, and the levatores ani and coccygei below. The levators arise 
along a line from the body of the pubic bone to the ischial spine, pass downward 
toward the median line, and there blend, thus forming the greatest part of the 
sagging floor of the pelvic cavity. This floor is perforated by the rectum, and in 
the female by the vagina also, and it separates the pelvic cavity from the sub- 
jacent perineal or ischio-rectal space. All of these parietal structures are lined 
by the pelvic fascia, which also gives support to the viscera. 
Two principal portions of the pelvic fascia are recognized—the obturator 
fascia and the recto-vesical fascia. 
The Obturator Fascia. 
The obturator fascia, so named from its lying upon the surface of the obtu- 
rator interims muscle, is attached to the bone around the margin of the muscle, 
being continuous with the obturator membrane beneath the obturator vessels, and, 
extending back to the front of the sacrum, covers the pyriformis and the sacral 
nerves, in this region being much attenuated. This hind portion is sometimes THE FASCIAE OF THE PERINEUM. 
361 
called the pyriformis fascia. As the obturator interims leaves the pelvis it takes 
with it a reflection of its fascia, which thus becomes continuous with the fascia 
which invests the muscles in the hip and thigh. 
The Recto-vesical Fascia. 
Along the curved line which marks the upper border of the origin of the 
levator ani (i. e., from the symphysis pubis to the ischial spine) the fascia is 
somewhat thickened, and is called the white line (arcus tendineus, linea albuginea). 
From this line the recto-vesical fascia arises, and extends toward the median line 
in close contact with the upper surface of the levator ani. When it reaches the 
bladder, it splits into two layers, one of which spreads upward and disappears in 
the wall of this viscus, and the other passes downward upon the prostate gland, 
and thus forms its sheath. The portion around the prostate is continuous with 
the upper layer of the triangular ligament, which will presently be described. 
When the recto-vesical fascia reaches the rectum, its fibres intermingle with 
of this intestine. In the female the fascia forms a partial covering to the 
' ertain portions of the recto-vesical fascia are described as the true ligaments 
of the bladder; but the lateral and the posterior are generally so indistinct as to 
be demonstrable with difficulty, if at all, and only the anterior are constantly 
worthy of mention. 
A. little to each side of the median line a fold of the fascia runs forward from 
the bladder, and attaches itself to the body of the pubic bone. This fold encloses 
a small bundle of muscular tissue, which is called, from the parts which it con- 
nects the vesica-pubic muscle. Thus are formed the anterior ligaments of the 
bladder. Between these two ridges is a median depression, in which the fascia 
is thin. 
THE FASCL® OF THE PERINEUM. 
The deep fascia of the perineum forms a triangle with its apex forward. It 
extends nearly horizontally sidewise between the lateral walls of the pelvis, and 
ventro-dorsally from the pubic symphysis to the central point of the perineum, 
which is about an inch in front of the anus. At the base of the triangle the fascia 
is single, but immediately splits into two layers, the superficial and the deep, 
between which are situated the constrictor muscle of the urethra Cowper s (sub- 
urethral) elands, vessels and nerves, as well as a part of the urethra. From this 
last fact and its shape the fascia is most commonly known as the triangular hga- 
ment of the urethra. . . , . , . . . 
The superficial (inferior) layer stretches between the isch.o-pubic rami 
strengthened near the front by a fibrous baud, called the trarmerse ligament of 
the /('*'«• -a lmjer is fastened laterally to the obturator fascia, just 
above the latter's attachment to the pubic and ischial rami. 
In the female the vagina perforates us ascia. 
The superficial fascia requires more attention in the perineum than in most 
other localities. Its deep layer is rather firm and close, and is attached at the 
sides to the entire lower border of the isch.o-pubic ram. and the ischial tuberosi- 
ties Its hind margin is united to that of the triangular ligament, between which 
structure and it are the transversus pennei muscles Between this deep layer 
and the skin is the superficial layer, loose and areolar, its spaces occupied with fat- 
1 The name ischurreetalfossa is applied to the considerable space on each side 
between the saveing floor of the pelvis and the osseo-muscular pelvic wall. 
These fossie are commonly filled with adipose tissue, which is continuous with 
that subjacent to the skin of the buttocks. 362 
THE FASCIHJ. 
THE FASCL® OF THE HIP AND THIGH. 
These structures are not separated by a clearly defined boundary, and will 
be considered as one, which, on account of its great extent, is commonly called 
fascia lata (“ the broad band ”). It is cylindrical in shape, and extends from 
the highest margin of the hip to the lowest limit of the thigh. At its upper 
end it is attached along an irregular line, which lies successively upon the 
coccyx, sacrum, iliac crest, the inguinal (Poupart’s) ligament, the body and 
descending ramus of the os pubis, ascending ramus and tuberosity of the 
ischium, and the great sacro-sciatic ligament, thus completing the circuit. It 
also has an attachment to the ilio-pectineal line, which will be mentioned again 
presently. It is continuous below with the fascia of the leg, is attached by 
its deep surface to the bony prominences around the knee, and contributes to the 
formation of the capsular ligament of this joint. In most parts it is a single 
layer, but, in the region of the gluteus maximus, it has two lamellae, which 
ensheathe the muscle, and a similar arrangement obtains in the case of the 
tensor vaginae femoris, otherwise called the tensor fasciae latae. The portion of 
the fascia on the outer aspect of the thigh is the strongest, and is called the ilio- 
tibial band, from its attachments at the iliac crest and the outer tuberosity of the 
tibia. The fascia sends inward to the femur two intermuscular septa, which par- 
tition the thigh into an anterior compartment and a posterior, the former contain- 
ing the quadriceps and sartorius, the latter the other muscles. These septa, exter- 
nal and internal, have their osseous attachments respectively upon the outer and 
inner lips of the linea aspera and their upward and downward prolongations. 
Other and less important septa also occur. Just below the median end of the 
inguinal (Poupart’s) ligament is an oval hole, measuring about an inch in its long 
(vertical) diameter, and called the saphenous opening, from its transmission of the 
long saphenous vein. The part of the fascia at the outer side of this aperture is 
the iliac portion; the part at the inner side is the pubic portion. The saphe- 
nous opening may be regarded as a notch in the upper border of the fascia, the 
angles of the notch overlapping each other without contact, so that the opening 
has not a continuous margin. The part of the margin which comes in front is 
continuous with the inner end of the inguinal (Poupart’s) ligament; that which 
goes to the rear curves backward, and is attached to the ilio-pectineal line. The 
upper, outer, and under portions of the 
rim taken together are sickle-shaped, and 
bear the name of falciform process. It is 
attached to the front of the sheath of the 
femoral vessels. Behind the plane of the 
saphenous opening are the upper parts of 
the femoral vessels, enclosed in a funnel- 
shaped sheath, which lies close to the 
artery, but is separated from the vein by 
an interval. This space constitutes a 
passage, the femoral or crural canal (Fig. 
419), whose upper or abdominal end has 
already been described as the femoral or 
crural ring. It is through this canal that 
a femoral hernia descends. The saphe- 
nous opening is closed in by a thin layer 
FEMORAL 
ILIO-1 
PECT. 
J3 <V N D- 
: FEMORAL 
EI N 
GIMBERNAT’S LIGAMENT 
INGUINAL LIGAMENT 
PUBIC SPINE 
Fig. 419.—The femoral canal. (Testut.) 
of areolar tissue (superficial fascia), which, from its being perforated by many 
vessels, suggests a sieve, and hence is called the cribriform fascia. 
THE FASCL® OF THE LEG 
The principal fascia of the leg is directly continuous with that of the thigh 
above and that of the foot below. It is not, however, a complete enclosure for THE FASCIAE OF THE LEG. 
363 
the leg, being deficient at the places where the bony framework is subcutaneous. 
For example, at the inner surface of the tibia the fascia merges with the perios- 
teum at the borders of this area; and it is disposed in like manner at the heads 
of the tibia and fibula, and at the malleoli. It sends intermuscular partitions 
inward at several points, the most perfect of them being two on the outer side of 
the W which have bony attachments along the neighboring borders of the fibula, 
and separate the peronei longus and brevis from 
the front and back groups of muscles respectively. 
Between the muscles which are inserted into the 
calcaneum and the other posterior muscles is 
stretched the deep transverse fascia, attached to 
the tibia and fibula, and binding down the mus- 
cles in front of it. 
In the region of the ankle the fascia is 
strengthened and to some extent prolonged into 
the foot by a series of transverse bands, which 
nearly encircles the limb, each of its primary 
divisions being called an annular ligament. 
They are three in number—anterior, internal, 
and external. The anterior annular ligament 
(Fio1 420) consists of two parts, an upper 
and a lower. The upper band runs across the 
front of the leg between the anterior borders 
of the tibia and fibula, just above the malleoli, 
keeping the vertical tendons in place. Ihe 
lower band begins on the outer side of the calca- 
neum, and splits into two layers at the outer bor- 
der of the peroneus tertius, one going in front 
and the other behind; at the inner border of the 
extensor longus digitorum the layers unite, thus 
forming a channel through which these two mus- 
cles pass. The band then divides into two 
branches—a superior, which goes upward to the 
front of the inner malleolus, and is there attached , 
and a lower, which crosses to its insertion on the 
scaphoid and internal cuneiform bones and in the 
plantar fascia. These bands confine the tendons 
of the tibialis anterior and extensoi propnus 
hallucis closely to the subjacent structures. Each 
of the last-named has a synovial sheath, but the 
extensor longus digitorum and peroneus tertius 
have one in common. The internal annular liga- 
ment (Fig. 421) is stretched between the mtei|fJ 
malleolus and the postero-infenor par ■ 
inner surface of the os calcis. viom _ 1 
surface processes are given off to tie neig 
in a- ridcres of bone, thus forming compartments 
Fig. 420.—The anterior annular liga- 
ment of the ankle and the synovial mem- 
branes of the tendons beneath it arti- 
ficially distended. (Testut.) 
through which pass the tendons of muscles rom . 
the hack of the leg to the sole of the foot, as fo lows : next behind the malleolus 
~ ~ i. i• , iilon +|lP flexor longus digitorum, and, finally, after an inter- 
the tibialis posterior hen fl|xor lo’gus Uoc£ Each of the 
taid'ol.s synovial membrane. The external annular ligament (Fig. 
foo ZrfromX tip of the external malleolus to the outer side of the ealoa- 
neum, binding down the peroneus longus and peroneus brevis, which are enclosed 
together in a single synovial membrane. 364 
THE FASCIAE. 
THE FASCL® OF THE FOOT. 
The homology of the fasciae of the foot and hand is so marked that it is 
unnecessary to dwell minutely upon the former, the latter having been already 
described. That in the sole is called the plantar fascia, and is divided into 
three parts. The central portion starts from the inner tuberosity of the calca- 
neum, runs forward below the flexor brevis digitorum, and terminates in front in 
a process for each toe and in slips for the skin. At the sides it is continuous with 
Fig. 421.—The internal annular ligament of the ankle 
and the artificially distended synovial membranes of the 
tendons which it confines. (Testut.) 
Fig. 422.—The external annular ligament of the 
ankle and the artificially distended synovial mem- 
brane of the tendons which it confines. (Testut.) 
the lateral portions, which extend around the margins of the foot. Where the 
central portion joins each lateral a process passes upward, and thus are formed 
partitions between corresponding groups of muscles. The external lateral por- 
tion is attached behind to the calcaneum, the internal to the internal annular liga- 
ment. The interosseous fasciae, the dorsal fascia, and the superficial transverse 
ligament of the toes, all are similar to their homologues in the upper limb, but 
the last named connects five digits, instead of only four. The tendons of the toes 
are kept in place by fibrous bands, and are provided with synovial membranes, as 
are the corresponding organs in the hand. THE BLOOD-VASCULAR SYSTEM 
THE blood is the vehicle by which nourishing materials are carried to the tis- 
sues, and many effete substances conveyed away from them. It is contained 
in a continuous series of chambers and tubes, which constitute the blood-vascular 
system. The chambers are the compartments of the heart, and the tubes are the 
arteries, the capillaries, and the veins—including under the last term not only the 
veins proper, but also certain channels which are called venous sinuses. The 
arteries are the vessels which carry blood from the heart to the tissues ; the capil- 
laries are those through whose delicate walls the interchange of nutrient and 
waste matters takes place in the midst of the tissues; and the veins are the vessels 
which convey the blood from the tissues to the heart. The whole blood-vascular 
system is closed in the normal condition, and no blood escapes from it, with two 
exceptions, which are as follows : in the female, during the child-bearing portion 
of her life, there is a periodical discharge of blood through ruptured vessels; and 
in the spleen of all persons the blood leaves the minute vessels, and flows through 
wall-less tubes in the parenchyma of the organ. 
In the entire blood-vascular system one structural feature is constant—the 
serous membrane which lines it. Muscular and fibrous coats in most parts are 
found surrounding the serous, but they are not, like it, invariable. The import- 
ance of this smoothest of all membranes as a lining for the heart and vessels is 
appreciated, when we consider that any roughness of a surface over which blood 
flows causes clotting of the fluid, and this results in the plugging of vessels, and 
the consequent starvation of the parts which they should supply with blood. 
THE HEART. 
F. H. GEBRLSH. 
The heart (Latin cor, or cardia) is the central organ of the vascular system. 
It is the force-pump which propels the blood through the vessels. In some 
animals it has but one cavity, in others it has two, in still others three. In man 
there are really two hearts, each having two chambers. The two hearts in the 
adult may be compared to a block of two houses, which are independent of each 
other except for the fact that the partition wall between them is common to both. 
During intrauterine life there is a door of communication between the upper 
chamber of one and the corresponding cavity of the other; but this is closed at 
birth, and thenceforward the blood cannot get from one side to the other without 
leaving the heart and going by a roundabout path. 
These two hearts are called, on the basis of their independence, the right 
heart and the left heart respectively ; on the ground of their union, they are named 
the right side of the heart and the left side of the heart respectively. Both sets 
of designations are misleading as regards the relative situation of the two organs 
(or sides of the same organ), for they are not placed right and left, but one—the 
right—is in front of the other. One chamber of each is called auricle, because 
of the resemblance of an appendage of it to an animal's external ear; the other 
365 366 
THE BLOOD-VASCULAR SYSTEM. 
chamber is named ventricle, from its bulging like a prominent abdomen. The 
auricles are spoken of as if they were entirely on a higher level than the ventri- 
cles, whereas they are nearly on the same plane. 
Each auricle receives blood from veins, and delivers it to the corresponding 
ventricle, which then discharges it through an artery. 
The Circulation of the Blood. 
The course of the blood is as follows : (Fig, 423) Beginning in the auricle 
of the right side, the blood, which has just come from the tissues of the entire 
body, passes through the large aperture by which the auricle communicates with 
its ventricle, and which is called the right 
anriculo-ventricular opening; from the 
right ventricle it is driven through the 
pulmonary artery to the lungs, through the 
walls of whose capillaries it loses certain 
impurities and gains oxygen from the air, 
thus being changed from venous blood to 
arterial; from the lungs it flows through 
the pulmonary veins to the left auricle, 
thence through the left auriculo-ventricular 
opening to the left ventricle, whence it is 
forced into the aorta, the great trunk of the 
general arterial system, and by this and its 
branches it is distributed throughout the 
body. From the twigs of the arterial sys- 
tem the blood is poured into the capil- 
laries, and here parts with nourishing 
materials, synchronously receiving a load of 
etfete substances, in this way being altered 
from arterial to venous. From the capil- 
laries it courses into the veins, which con- 
duct it to the right auricle, the place from 
which the reckoning began. This descrip- 
tion of the track of the blood confirms the 
statement previously made that the com- 
munication between the right and left sides 
of the heart is not direct, through the par- 
tition wall, but is entirely indirect—it 
being necessary for the blood to go out of 
the heart and through the capillaries of 
some organ in order to get from either side 
to the other. 
The journey of the blood from the right 
Fig. 423.—Diagram to show the course of the 
blood in passing from a given point through the 
two sets of capillaries to the starting point. (F. 
H. G.) 
heart to the left through the capillaries of the lungs is the less or pulmonary cir- 
culation ; and the passage of the blood from the left heart to the right through the 
capillaries of the organs of the body is the great or systemic circulation. It is to 
be noted that, in going through the lung-capillaries, the blood is changed from 
venous to arterial; and that, in its course through the capillaries of the general 
system, the reverse occurs—it is altered from arterial to venous. The kind of 
blood contained in a vessel does not, however, make the latter either vein or 
artery, as the pulmonary artery bears foul or venous blood, and the pulmonary 
veins are full of purified or arterial blood. Arteries carry blood, red or blue, 
from the heart; veins carry blood, blue or red, to the heart. 
The Tissues of the Heart.—The lining of the heart, like that of all other parts 
of the vascular system, is serous membrane, and is called endocardium (“ within 
the heart”). The outer covering, too, is serous, and is called pericardium THE HEART. 
367 
(“around the heart”). It will be described in detail on a subsequent page. 
Between the endocardium and the pericardium is a middle coat, which is muscular 
and fibrous, and, on account of the enormous preponderance of the contractile 
tissue is named myocardium (“muscle of the heart”). The muscular tissue 
is of the cardiac variety. The arrangement of the bundles of fibres is extremely 
intricate, and not yet fully understood in all of its details. 
The Thickness of the Cardiac Walls.—The muscular walls of the right auricle 
are thin and so flabby that they fall together when the cavity is empty ; they 
have to drive the blood but a short distance—only into the ventricle—and through 
a very laro-e opening. The right ventricle has thick, firm walls, so powerful that 
by them the blood is sent through the 
pulmonary artery and its branches, into 
and through the numberless capillaries 
of the lungs, through the pulmonary 
veins, and into the left heart. The left 
auricle has walls but little thicker than 
those of the right, yet quite equal to the 
trifling labor placed upon them that 
of forcing the blood through the large 
auriculo-ventricular orifice into the left 
ventricle. The left ventricle by its con- 
traction must drive the blood through 
the vessels of the systemic circulation; 
and, as these are much more numerous 
than those of the pulmonary set, and 
Fig. 424.—Cross-section through both ventricles, 
showing the shape of their cavities and the relative 
thickness of their walls. (Testut.) 
present, on account of their situation, far greater frictional resistance to the pas- 
sage of the blood in proportion to their number, there is necessity for vastly 
greater power in the ventricular walls, which, in fact, are three times as thick as 
those of the right ventricle (Fig. 424). The bulging of the interventricular septum 
into the right ventricle is due to this greater thickness of the parietes of the left; 
indeed, this whole partition has the appearance of being formed by the latter. 
The auriculo-ventricular openings and those of the pulmonary artery and the 
aorta are guarded by valves, which do not interfere with the passage of the blood 
in the course already described, but do serve to prevent a return of blood to a 
cavity from which it has been discharged. 
The heart is situated in the lower and tront part ot the chest, extending much 
farther to the left side than to the right. It lies obliquely, the auricles being at 
the right of and a little higher than the ventricles. 
The Right Auricle (Fig. 425), when viewed from the inside, presents a main 
chamber the atrium (“ hall ”), and a little ante-chamber, the cavity of the 
appendix the latter being at the front and upper part of the auricle. A num- 
ber of openings are seen. At the back the two vence cavce enter, the superior 
above, the inferior below. The floor of the atrium is largely formed by a trap- 
door the tricuspid valve, which closes the oval auriculo-ventricular opening. 
Several cardiac veins of considerable size, returning blood from the substance of 
the heart itself open directly into the cavity, ihe largest of these is called the 
coronary sinus’ and enters between the inferior vena cava and the auriculo- 
ventricular orifice, its orifice being protected by a serous fold, the valve of 
Thebesius. There are also some very small veins, vence mvnimce cordis (“ the least 
veins of the heart”), whose apertures, together with others of similar appearance, 
which are said to be blind depressions, have been named foramina Thebesii 
(“ finlpq of Thebesius”'). On the hind wall, which is the partition between the 
two auricles, is a shallow depression, the fossa ovatis (“ oval pit”), bordered, 
except below by a ridge, the annulus ovahs ( oval ring ). The fossa marks the 
site of a hole (foramen ovale), which exists in the septum auricularum (“partition 
of the auricles'”) in intrauterine life, and at birth becomes permanently closed by 
a flap of membrane. Various projections from the surface are observed, some 368 
THE BLOOD-VASCULAR SYSTEM. 
being muscular, others merely folds of endocardium. A network of muscular 
ridges covers the wall of the appendix, and on the right wall of the atrium is a 
series of vertical bands of nearly equal size, not inaptly named musculi pectin ati 
(“comb-like muscles”). Connecting the margin of the inferior vena cava and 
the anterior edge of the annulus ovalis is a membranous fold, the Eustachian 
valve, which is prominent in proportion to the youth of the individual. In the 
foetus it serves to guide the blood from the inferior vena cava through the fora- 
men ovale of the septum into the left auricle. Between the openings of the 
vense cavse is an indistinct projection, the tubercle of Lower. 
ANNULUS 
OVALIS^ 
TUBERCLE. 
OF LOWER 
FOSSA 
OVALIS'7 
ANNULUS ..-X- 
-OVALIS / j 
RIGHT CORO- 
"NARY ARTERY 
EUSTACHIAN 
VALVE 
VALVE OF 
TH EBESIUS 
(TRICUSPID 
VALVE 
Fig. 425.—Right auricle and part of right ventricle, the front wall having been removed. (Testut.) 
OPENING OF'’ 
CORONARY SINUS 
The Right Ventricle has an irregular cavity, concave in front and convex behind, 
where the septum ventriculorum (“partition of the ventricles”) bulges into it. 
There are two large openings—the auriculo-ventricular orifice, and that of the 
pulmonary artery, the latter being at the apex of the infundibulum, a somewhat 
funnel-shaped portion of the chamber toward the left side. The auriculo-ven- 
tricular opening is closed by the tricuspid valve, so called from its three con- 
spicuous segments. These are of unequal size and irregular shape, having ragged 
and frayed free edges, and between their attached borders frequently small 
secondary segments. One flap is at the left, one at the right, and one behind. 
They are composed of white fibrous tissue, and their attached borders are united 
to a fibrous ring, which encircles the orifice. At the junction of the pulmonary 
artery with the heart is the pulmonary valve, made up of three fibrous festoons of 
semilunar shape (Fig. 429). The free edge of each is marked at its middle by a 
nodule, the corpus Arantii (“ body of Arantius ”). The attached margin is 
strengthened by a ring of fibrous tissue. Behind each flap is an enlargement of 
the arterial bore, making a little recess, the sinus of Valsalva. Many large mus- 
cular prominences, columnce carnece (“fleshy columns ”), are observed everywhere, 
except in the infundibulum (Fig. 426). Of these there are three kinds : those 
that are sculptured in high relief from the wall—attached at both ends and all of 
one side ; those that are fastened at both ends and nowhere else ; and those that 
have only one extremity secured to the wall. The last are known as papillary 
muscles, because they stand out like nipples, and they are arranged in two princi- THE HEART. 
369 
pal sets, anterior and posterior. From their summits project delicate tendons, 
chordce tendinece, which are inserted into the free edges and under sides of the 
flaps of the tricuspid valve. Running across the chamber obliquely is usually a 
prominent muscular beam, the moderator band. 
Action.—When the muscular wall of the ventricle contracts, the cavity is 
practically obliterated, and its contents are discharged. As soon as contraction 
begins, the tricuspid valve is closed, and, were it not for the special restraining 
apparatus, its flaps would be swept into the auricle, and the greater part of the 
blood in the ventricle would go with them. But the papillary muscles come into 
action simultaneously with all other parts of the wall, and pull the valve down- 
ward exactly to the extent that the blood tends to push it upward beyond the 
plane at which the free margins of its segments come in close contact. Thus 
ree’ure'itation is prevented, and the blood is 
forced through the only other avenue of 
escape, the pulmonary artery. The con- 
traction of the ventricle ceasing, the dis- 
tended artery has a tendency to return 
some of its contents to the ventricle; but, 
as soon as the column of fluid starts back- 
ward, the semilunar festoons, which have 
been flattened by the outrush of blood 
from the heart, are closed with a snap, the 
accumulation in the sinuses behind them 
giving the first impulse, and the pressure 
of the fluid in the artery completing the 
act. In this way not a drop is allowed to 
regurgitate. The columnse carnese of the 
second and third varieties are useful in 
regulating contraction and evenly dis- 
tributing pressure, the moderator band 
being of especial service in preventing too 
great distention and in causing approxima- 
FrG 426 _The three varieties of column£e 
came®, (f. h. g.) 
tion of the opposite walls. 
The Left Auricle presents fewer irregularities of internal surface than does the 
right (Fig. 427). The musculi pectinati are less numerous and less pronounced. 
Toward the rear on each side are the orifices of two pulmonary veins. The posi- 
tion of the foetal foramen ovale is indicated by a slight indentation on the septal 
wall. The auricula-ventricular opening is much like that in the right heart, but a 
little smaller. It is guarded by the bicuspid valve. 
The Left Ventricle has a capacity equal to that of the right, but its cavity has 
a different shape, being ovoidal. In general features it strongly resembles the 
other ventricle. The three varieties of columnce carnece. are present; but, while 
these muscular bundles are more numerous, they are of less size. The papillary 
muscles are disposed in two series. A band, similar to the moderator of the right 
ventricle, but much smaller, crosses the chamber. At the uppermost part of the 
septum the wall is fibrous and very thin, constituting a weak area, sometimes 
called the undefended space. The auriculo-ventricular orifice and that of the 
aorta are very close together, the former being toward the rear, the latter near the 
front. The auriculo-ventricular valve is called bicuspid, on account of its having 
two chief segments, and mitral, because these flaps, when open, are somewhat 
suggestive of a bishop’s mitre (Fig. 428). One segment lies close to the hind 
wall, the other and larger is between the two orifices. I requently small second- 
ary segments are found between the two great flaps. The valve is connected with 
papillary muscles by chordce tendinece., and in general features of structure is like 
the tricuspid, already described. The valve at the base ot the aorta (Fig. 429) is 
a repetition of that of the pulmonary artery, except that in almost every respect 
its characteristics are more pronounced. The semilunar segments are situated 370 
THE BLOOD-VASCULAR SYSTEM. 
respectively in front, at the left behind, and at the right behind. From the 
sinus of the first of these is given off the right (anterior) coronary artery, and from 
that of the second the left (posterior) coronary artery springs. These vessels are 
RIGHT PULMO - 
/ (NARY VEINS 
LEFT PULMON- 
ARY VEINS 
LEFT AURICULAR 
APPENDIX 
POSTERIOR CORO- 
NARY VESSELS 
ANTERIOR CORO- 
NARY VESSELS 
DART POINTING TO.. 
AORTIC OPENING 
f ANTERIOR COLUMNA 
I CARNEA CUT IN TWO 
j AND LIFTED UP AND 
I BACK 
■ EXTERNAL FLAP OF 
MITRAL VALVE 
CAVITY OF LEFT. 
VENTRICLE 
BASE OF ANTERIOR.. 
COLUMNA CARNEA 
called coronary because they encircle the heart like the band of a crown. They 
are the first branches of the aorta, and feed the heart. Between the auriculo- 
Fig. 427.—Left auricle and ventricle, the hind wall of each having been removed. (Testut.) 
Fig. 428.—Valves of the heart and great arteries, viewed from above, the auricles having been removed, 
(Testut.) 
ventricular and aortic orifices is a mass of mingled white fibrous tissue and white 
fibro-cartilage, from which are given off fibrous prolongations forming rings 
around the openings, and so stiffening their margins that stretching is prevented. THE HEART. 
371 
The bulk of the heart has been said to be approximately that of the fist of its 
owner; but to this rough-and-ready rule there are so many exceptions as to 
render it of little value. During life the diameters of the heart are constantly 
changing, and measurements made after death may be misleading. It increases 
in weight and volume with rather unsteady progression to the end of life. Its 
average weight in the male is about eleven ounces ; in the female it is somewhat 
less. Its blood-vessels are the coronary arteries and veins. It has numerous 
lymphatics. The nerve-supply is derived from the pneumogastric and from fibres 
of the cervical and thoracic ganglia of the sympathetic. 
OPENING OF RIGHT 
CORONARY ARTERY 
SINUS OF , 
VALSALVA / 
OPENING OF LEFT 
CORONARY ARTERY 
RIGHT: 
SEGMENT 
CORPUS* 
ARANTII 
FIBROUS THICKEN- 
ING OF EDGE 
*** LEFT 
SEGMENT 
POSTERIOR 
SEGMENT 
Fig. 429.—Aortic valves. The artery has been cut open between the right and left segments, and spread 
out. (Testut.) 
The External Configuration of the Heart. 
The Grooves of the Heart.—The surface of the heart is marked by a series of 
grooves, which indicate the superficial limits of the various cavities. 
Between the auricles and ventricles is the auricula-ventricular groove, which is 
incomplete in front, where the anterior surface of the pulmonary artery is con- 
tinuous with that of the right ventricle. This vessel occupies the broad ventral 
depression between the auricles—the anterior inter auricular groove. The posterior 
inter auricular groove lies between the right pulmonary veins and the portion of 
the right auricle which connects the superior and inferior vena? cavse. 
Between the ventricles are the interventricular grooves, which are continuous 
at the right of the apex of the heart. The anterior interventricular groove begins 
between the pulmonary artery arid the left auricular appendix, and runs down- 
ward upon the ventral surface of the heart. Ihe posterior interventricular 
groove starts at the left of the inferior vena cava, almost in continuation of the 
posterior interauricular groove, and courses forward upon the inferior surface of 
the organ. 
The Surfaces of the Heart.—\\ lien the heart has been hardened while main- 
taining its natural relations with contiguous organs, it presents six surfaces, sep- 
arated from one another by borders, which are defined with varying degrees of 
distinctness. 
The Ventral Surface (Fig. 430) is slightly convex, irregularly quadrilateral, 
and looks forward and a little upward. It presents the front of the right ven- 
tricle, a part of the right auricle, of both appendixes, and of the left ventricle. 
The right (anterior) coronary artery is seen in the right auriculo-ventricular 
groove, giving off branches, of which the principal are the preventricular above, 
and the right (anterior) marginal below, the latter running to the left near the 
lower border. The anterior interventricular groove lodges a branch of the left 
(posterior) coronary artery and the great coronary vein. The ventral surface is 
bounded by the ill-defined right border, which falls upon the convex surface of 372 
THE BLOOD-VASCULAR SYSTEM. 
the right auricle ; below by the antero-inferior harder, which separates it from the 
inferior surface, and is so sharp that it is called margo acutus; on the left by the 
Left border, on the marked convexity of the left ventricle; and above by the line 
of junction of the pulmonary artery with the heart, and by the upper margin of 
the appendixes. 
The Dorsal Surface (Fig. 431) is irregularly convex, looks backward, and pre- 
sents the greater part of the left auricle. Above are the horizontally directed 
primary divisions of the pulmonary artery, the right and left pulmonary arteries ; 
at the right the posterior interauricular groove; below, the auriculo-ventricular 
vena! 
IcavaJ 
SUP. I 
AORTA 
'PULMONARY 
ARTERY I 
/ RIGHT 
AURICLE 
L LEFT IMil| 
|vENTRI:^B 
RIGHT 
VENTRI CLE 
Fig. 430.—Front view of the heart. The auriculo-ventricular and anterior interventricular grooves and 
the vessels in them are not labelled, but cannot be mistaken. (From the His cast. F. H. G.) 
groove ; at the left a line leading downward from the left pulmonary veins, 
commonly marked by the oblique vein (of Marshall), which ends below in the 
coronary sinus. 
The Right Surface is convex, quadrilateral, and exhibits nearly all of the right 
auricle which is not included in the ventral surface. At the postero-inferior 
angle the vena cava inferior enters, and the vena cava superior is seen above. 
Behind is the posterior interauricular groove ; below, the auriculo-ventricular 
groove; and in front is the right border, already mentioned. 
The Left Surface is unevenly convex and somewhat triangular. It presents 
above and behind a part of the left auricle, and in front of this a portion of its 
appendix ; below, the left ventricle, tapering to the apex, and showing in the THE HEART. 
373 
midst of this space the marginal branch of the left coronary artery and the left 
marginal vein; and, between the auricle and ventricle, the great coronary vein. 
The Inferior Surface is nearly flat, and looks downward and backward, con- 
forming to the sloping upper surface of the anterior portion of the diaphragm. 
Here are seen parts of both ventricles, separated by the posterior interventricular 
groove, which lodges the interventricular branch of the right coronary artery and 
the middle cardiac vein; and at the back and right a small part of the right 
auricle and the aperture of entrance of the vena cava inferior. 
The Upper Surface is small and irregular, and is occupied by the great vessels 
which form the bulk of the stem of the heart—the pulmonary artery, the aorta, 
and the vena cava superior. 
LEFT 
AURICLE 
LEFT 
V E NTRI OLE 
Fig. 431.—Rear view of the heart, showing the dorsal and inferior surfaces. The latter is represented as 
convex, hut should be nearly flat. (Modified from the His cast. P. H. G.) 
The ventral, inferior, and left surfaces converge at the left anterior portion of 
the heart to a blunted point, called the apex. This is constituted entirely by the 
left ventricle, owing to the fact that the wall of this chamber is very much 
thicker than that of the right ventricle. The apex lies behind the space between 
the fifth and sixth costal cartilages, about three and a half inches from the middle 
line. 
THE PERICARDIUM. 
The pericardium (u around the heart ”) is the sac in which the heart is con- 
tained (Fig. 432). It consists of two parts : (1) an external, fibrous portion, and 
(2) an internal, serous portion. 
The fibrous hag, composed mostly of white fibrous tissue, somewhat loosely 
encloses the heart, and is attached to various structures in the immediate neigh- 
borhood. Inferiority it is firmly adherent to the diaphragm, with whose central 374 
THE BLOOD-VASCULAB SYSTEM. 
tendon its fibres are intermingled. It extends upward onto the great vessels for 
two inches or more, blending with their sheaths ; and in this region it is also con- 
tinuous with a downward prolongation of the cervical fascia. In front it is con- 
nected with the breast-bone by two fibrous bands, the superior and inferior sterno- 
pericardial ligaments ; and the parietal pleurae are adherent to its lateral surfaces. 
The serous membrane furnishes a lining to the fibrous bag, and is thence 
reflected onto the contained organs, giving them a closely attached covering. The 
lining of the fibrous pouch is the parietal portion of the serous membrane, and 
.UPPER ATTACHMENT 
j OF PERICARDIUM 
SUPERIOR * 
VENA CAVAj 
|1 BRANCHES OF 
JFULMONARYARTERY 
W /'PULMONARY 
ARTERY 
BRANCHES OF PUL 
MONARY ARTERY 
AORTA-* 
LEFT 
AURICLE 
RIGHT 
AURICLE*'* 
DIAPHRAGM PERICARDIUM 
RIGHT ATTACHMENT OF 
VENTRICLE PERICARDIUM DIAPHRAGM 
Fig. 432.—The heart in situ. The pericardium has been cut open in front, and reflected. (Testut.) 
TO DIAPHRAGM 
the clothing of the heart and vessels is the visceral portion, the latter sometimes 
being called the epicardium (“upon the heart”). Thus, the heart, which changes 
its position seventy times a minute all through life, is enabled to move with the 
least possible friction. 
The pericardium does not completely encase all of the vessels attached to the 
heart. The aorta and pulmonary artery are enclosed in one sheath, the others are 
only partially covered. Many pouches of pericardium are found between the 
vessels at the lines of reflection of the membrane. 
The arteries which supply the pericardium are the internal mammary, phrenic, 
pericardiac, oesophageal, and bronchial. Its nerve-supply comes from the pneu- 
mogastric, phrenic, and sympathetic. 
THE PHYSIOLOGICAL ANATOMY OF THE BLOOD-VESSELS. 
Before one studies the systematic anatomy of the blood-vessels, it is important 
that he should know their physiological anatomy. The few succeeding pages, 
therefore, will be devoted to a presentation of the principal features of the struct- 
ure of the different kinds of vessels, with especial reference to the relations 
between their histological composition and their functions. THE HEART. 
375 
The Arteries. 
The arteries (arterice) are the tubes by which blood is carried away from the 
heart. The name etymologically conveys the idea that these vessels are air- 
bearers, the ancients regarding them as performing the function of distributing 
air to the tissues, because they contain no blood or other liquid after death. But 
although this belief was long ago exploded, the name is not altogether inappro- 
priate, and may be considered a prophetic blunder; for physiology demon- 
strates that the blood in the arteries is laden with oxygen, which is the essential 
nourishing ingredient in the air, and the most important element in the income 
of the body. 
The Coats of Arteries.—An artery has three coats—an inner, a middle, and an 
outer. The points of especial practical value about these tunics are as follows : 
the inner coat (tunica intima) is serous, 
like the lining of every other portion 
of the vascular system ; the outer coat 
(tunica adventitia) is composed of 
white fibrous tissue, with its bundles 
arranged longitudinally ; and between 
these two is the middle coat (tunica 
media), made up of plain muscular 
and yellow fibrous tissues (Fig. 433). 
While this statement of the struct- 
ure of the arteries embraces the es- 
sential features of their physiological 
-OUTER COAT 
-ELASTIC LAYER ) MIDDLE 
CONTRACTILE LAVER \ COAT 
-INNER COAT 
Fig. 433.—Diagram of a cross-section of an artery, 
showing the composition ol its tunics. (F. H. G.) 
anatomy, a somewhat detailed description will not be out of place. The inner 
coat has three layers: an epithelial, consisting of flat, polygonal cells; a sub- 
epithelial, of white fibrous tissue, with sometimes yellow fibrous ; and an elastic, 
of yellow fibrous tissue, closely reticu- 
lated. The middle coat is composed of 
plain muscular fibres, arranged crosswise 
in layers (Fig. 434), between which there 
is more or less yellow fibrous tissue. 
The outer coat, mostly of white fibrous, 
contains yellow fibres. Thus it appears 
Fig. 434.—Diagram of the arrangement of mus- 
cle-cells in an arteriole. (F. H, G.) 
that each tunic has some elastic tissue, the bulk of which, however, is an ingre- 
dient, of the middle one. 
The Functions of the Arterial Coats.—The inner tunic by its smoothness reduces 
the friction of the blood-current to its lowest terms ; the outer by its strength and 
toughness is protective ; the middle by virtue of its elasticity enables the vessel to 
return passively to its average diameter after it has been distended, and on 
account of its contractility serves actively to reduce the bore of the tube to less 
than its average. The larger the artery the greater is the relative amount of yel- 
low fibrous tissue; and the smaller the artery the greater the relative amount of 
muscular tissue. The relativity of the quantity of these ingredients should be 
carefully noted; for, while the comparative contribution of muscle to a minute 
arterv is great, its absolute amount is very small. From these facts it may be 
inferred that the large arteries are very elastic and but slightly contractile ; the 
small are highly contractile, and only feebly elastic; and those of medium size 
possess both of these attributes to a considerable extent, the one or the other pre- 
dominating according to the degree of nearness to the distal or the proximal 
limits of the arterial system. 
Vessels and Nerves of Arteries.—Outside of the artery is an enclosing sheath 
of areolar tissue in which are situated the nerves and blood-vessels of the artery 
itself. These are called respectively nervi arteriarum and vasa arteriarum; but, 
as the veins are similarly provided, generic, instead of the above specific, names 
are more frequently used—nervi vasorum and vasa vasorum, respectively “ the 
nerves of the vessels ” and “ the vessels of the vessels.” In surgical operations 376 
THE BLOOD-VASCULAR SYSTEM. 
it is important to avoid unnecessary separation of the sheath from the artery, 
because the destruction of the feeding vessels of the latter deprives the part of its 
nourishment, and results in its death. The vasa vasorum are either branches of 
the artery which they supply, being given off a little distance above their areas 
of distribution, or else they are contributed by a neighboring artery. 
The Branching of Arteries.—The arterial system is aptly compared to a tree, 
from whose trunk many large branches spring, each of these giving origin to 
smaller branches, and so on until the most diminutive twigs are reached. Various 
methods of branching are observed in arteries (Fig. 435). Often an artery 
PLEXUS 
TERMINAL 
BRANCHES 
ANASTOMOSIS 
SIDE _ 
branch- 
AXls\ 
/YunionA 
/ BY \ 
vjonver/ 
\gence 
HRECURRENT 
/ BRANCH 
DICHOTOMOUS \ 
BRANCHING 
main TRUNK 
Fig. 435.—Diagram showing the branchings, anastomoses, and confluence of arteries. (F. H. G.) 
divides into two terminal branches of nearly equal size, this method being called 
dichotomous, because the end of the vessel is split in two. Rarely an artery 
terminates in three approximately equal branches that diverge from the parent 
stem, which hence is called an axis. Most branches spring from the sides of an 
artery, and are, consequently, said to be given off in its course. These lateral 
branches usually form acute angles with their trunk, but sometimes right angles, 
and occasionally obtuse. 
The sectional area of an artery is always less beyond the point at which a 
branch springs from it; but the combined sectional area of the immediate 
branches of an artery is always greater than that of the trunk from which they 
originate. Consequently, the capacity of the arterial system at any given distance 
from the heart exceeds that at any plane proximal to this, and thus there is vastly 
more blood in the smallest arteries (arterioles) than in the aorta and pulmonary 
artery, which receive the fluid directly from the heart. 
Arteries generally pursue a course which is substantially straight or describes 
a generous curve ; but some are serpentine, presenting a tortuous appearance, and 
this condition obtains in localities where the parts are liable to great changes of 
form, in some of which the vessel, if straight during quiescence, would be sub- 
jected to destructive stretching. 
The course of the blood in the arteries is, as a rule, from centre to periphery; 
but exceptions occur, as in the case of the so-called recurrent arteries, which run 
backward, carrying the blood toward the heart. These vessels are frequent about THE HEART. 
377 
movable joints, and insure a plentiful supply of blood, when extreme flexion 
interferes with the direct and usual provision. 
When the distal end of one artery is united to the end of another, so that the 
blood can flow in either direction, the arrangement constitutes an anastomosis, 
because the tubes are “ mouth to mouth,” and is also called an inosculation, which 
means “ a kissing by mouths.” Frequently a number of arteries form many and 
free inosculations within a limited area, thus making a network or plexus. Two 
arteries of equal size may unite, not by anastomosis, but to form a trunk, just as 
two venous radicles combine to constitute a larger vein. The vertebrals thus 
constitute the basilar artery. 
The Capillaries. 
At the periphery of the arterial system the vessels are microscopic, and con- 
sist of hardly more than the epithelium of the intima and a few scattered muscle- 
cells. When this imperfect contractile covering disappears, the vessel ceases to be 
an artery and becomes a capillary. The name capil- 
lary means hair-like; but these vessels are much 
finer than hairs, some of them having so narrow a 
lumen that a colored corpuscle of the blood cannot 
pass through it without being squeezed out of its 
normal shape. The length of a capillary is only a 
minute fraction of an inch. The wall of the tube is 
epithelial (Fig. 436), and is so thin that the materials 
of the blood pass through it into the spaces around 
the tissues, and the waste substances of the tissues 
traverse it in the opposite direction, and enter the 
blood. The capillaries are arranged in networks. 
The fineness of the vessels and the size and shape of 
the areas between them vary greatly. Thus, in the 
muscles the capillaries run between the fibres, and 
for the most part have a direction parallel with the 
fibres, the longitudinal being connected by obliquely 
Fig. 436.—Capillaries, showing 
the shape and arrangement of the 
cells which make their wall. (Car- 
penter.) 
crossing vessels, and enclosing long, narrow spaces, 
bounded by nearly straight lines; but in the air-vesicles of the lungs the capil- 
laries are tortuous, very large, irregular, and so closely placed that the distance 
between them in some places is less than their own diameter. Some capil- 
lary vessels come from veins instead of arteries. For example, the interlobular 
branches of the portal vein give off the capillary plexus within the lobule, and 
from this the blood is collected by the intralobular vein. 
The Veins. 
The veins are vessels which conduct the blood from the periphery toward the 
centre of the vascular system. They begin where the capillaries end. As the 
loss of the last semblance of a middle coat changes an arteriole into a capillary, 
so the addition of a tunic, however scanty, to a capillary converts it into a venule 
(“ little vein ”). The venous system is comparable to the portion of a tree which 
is in the ground. It begins in rootlets at the distal end of the capillaries (Fig. 
437). These minute veins are properly called radicles, and the same term is 
used to designate veins of any size, which by their confluence form a larger ves- 
sel. They are often called branches instead of radicles ; but the term “ branches ” 
should be restricted to vessels resulting from division rather than from union. 
The desirability of the distinction is perceived in cases where a vein divides into 
two or more veins. The last are clearly branches of a parent stem, but, at the 
same time, are radicles of one or more veins nearer the heart. 378 
THE BLOOD-VASCULAR SYSTEM. 
The veins are more numerous than the arteries, and the capacity of the venous 
system is considerably greater than that of the arterial. 
The veins have a structure, which in the main, is like that of the arteries ; but 
there are such variations of detail that, in some respects, the two sets of vessels 
behave very differently. The inner coot is essentially like the arterial intiraa, with 
the addition of numerous transverse folds, which, strengthened by plates of white 
fibrous tissue, form valves (Fig. 438). The middle tunic is thinner than that of 
the arteries of comparable size, contains less muscle, more white fibrous, and only 
a little yellow fibrous tissue. The external 
coat is very like that of the arteries. This 
combination results in vessels which are very 
strong, capable of sustaining more strain 
than arteries without giving way, but so 
flabby that they collapse when emptied of 
\bran-/ 
WHEs/ 
RADICLES 
Fig. 437.—Diagram, showing the formation of large 
veins by convergence of small, and the branching of 
veins. (F. H. G.) 
PLEXUS 
Fig. 438.—Valves of veins. A shows a vein cut 
open between the segments of two valves. B shows 
appearance of valves closed and open. (Testut.) 
blood ; whereas arteries, stiffened as they are with elastic and a large amount of 
muscular tissue, stand open in similar circumstances. 
The valves are not found in all veins. They generally have two flaps each, 
which are directed toward the heart, when open. At the base of each valve the 
vein bulges, forming a sinus, into which the blood enters as soon as any obstruc- 
tion to its flow occurs, and causes instant closure of the valve. 
A few exceptions are found to the rule that capillaries intervene between 
arterioles and venules. In the interior of erectile organs small arteries may 
open directly into venous cavities; and in the spleen the arteries discharge into 
the interstices of the organ. THE ARTERIES. 
A. D. BEVAN. 
THE arteries are the vessels which carry the blood from the right and left 
ventricles of the heart to all parts of the body. There are two sets of arte- 
ries, the pulmonary (“ lung ”), and the systemic. Each system begins as a single 
tube, continues as a single tube for a short distance, and then divides into 
branches. Each system resembles a tree with its trunk and branches. In 
studying each system the student should regard it as a whole, remem- 
bering that many of the divisions made are artificial, and that the whole 
system forms one continuous series of tubes. In the study of the arteries the 
student should follow some systematic plan, which will so fix in his memory a 
picture of the origin, and course, and relations of the arteries to surrounding 
structures, that this knowledge can be of service to him in his practical work. 
The pulmonary system is simple and easily mastered; the systemic requires 
much study. In studying the systemic system the student should make a sylla- 
bus of the entire system; then, beginning with the aorta, he should study each 
anatomical division separately, and should learn of each vessel the following 
facts : Its origin, course, termination, relations, branches, distribution, anasto- 
moses, variations, and surgical anatomy. In studying the vessels the drawing of 
longitudinal sketches and of sketches of transverse sections of the limbs and 
trunk at ditferent levels, showing the position of the vessels and the relation of 
the vessels to surrounding structures, will be found to be of great value. The 
vessels are best studied in the dissecting-room, but another valuable method of 
studying them is upon a living model. The external landmarks which guide the 
operator in the finding of, or in the avoiding of, a vessel in an operation are best 
fixed in the mind by the study of the living model. We shall follow therefore 
in this description of the systemic arteries the course outlined : 
I. A syllabus of the entire system. 
11. A detailed description of each vessel, giving its origin, course, termina- 
tion, branches, distribution, relations, anastomoses, variations, and surgical 
anatomy. 
We shall combine the study of the longitudinal course of the arteries with 
that of the vessels in transverse section, and shall study also the surgical anatomy 
involved in the ligation of the arteries. Before taking up the study of the 
systemic arteries, let us dispose of the pulmonary system, which can be briefly 
done. 
THE PULMONARY ARTERIAL SYSTEM. 
The Pulmonary Artery (Fig. 439) carries the venous blood from the right 
ventricle to the lungs. Its origin is from the right ventricle; its course is 
upward, backward, and to the left for the distance of two inches, the vessel being 
contained in the pericardial cavity. Its termination is at a point beneath the 
transverse portion of the aorta opposite the fifth dorsal vertebra. Here it divides 
into the right and left pulmonary. Its relations are as follows : 
379 380 
THE BLOOD-VASGULAB SYSTEM. 
• LEFT AURICU- 
LAR APPENDIX 
VENTRICLE 
RIGHT i 
VENTRICLE 
I 
BRONCHIAL 
TUBES 
RIGHT 
AURICLE 
Fig. 439.—The pulmonary artery. The front part of the right lung has been removed, and the pulmonary 
vessels and the bronchial tubes are thus exposed. (Testut.) 
Sternum and pericardium. 
In front. 
To the right. 
To the left 
Ascending aorta. 
Right auricle. 
Right coronary artery. 
Pulmonary 
Artery. 
Pericardium. 
Left pleura. 
Left auricle. 
Behind. 
Left coronary artery. 
Arch of aorta and left auricle. 
Its branches are the right and left pulmonary. The right pulmonary artery 
passes beneath the aortic arch to the right lung, breaks up into three sets of 
branches supplying the upper, the middle, and the inferior lobes. 
The left pulmonary artery passes in front of the descending aorta to the left 
lung, and breaks up into two sets of branches supplying the upper and lower 
lobes. 
It is to be remembered that the pulmonary arteries carry venous blood to the 
lobules of the lungs, in which it experiences the changes produced by the func- 
tion of respiration, the structure of the lungs being supplied with arterial blood 
by the bronchial arteries, branches of the descending aorta. The branches of the 
pulmonary arteries do not anastomose with each other : they are terminal arteries. 
Passing from the pulmonary artery to the arch of the aorta is a fibrous cord, 
the remains of the ductus arteriosus, a vessel, which in the foetal circulation 
carries the blood sent through the pulmonary artery into the aorta. After birth 
this soon disappears; but, as an abnormality, it may persist. THE ARTERIES. 
381 
A SYLLABUS OF THE SYSTEMIC ARTERIAL 
SYSTEM. 
The systemic arterial system begins as the aorta from the left ventricle at a 
point behind the left half of the sternum on a level with the lower border of the 
third costal cartilage. From this point it passes upward, forward, and to the 
right, to a point on a level with the upper border of the second costal cartilage. 
It then curves backward and to the left, to the lower border of the fourth thoracic 
vertebra ; and then passes downward on the bodies of the thoracic vertebrae, being 
placed in a position to the left of the median line at first, but gradually approach- 
ing the median line as it passes downward. The vessel then passes through the 
aortic opening in the diaphragm, passes downward on the bodies of the upper four 
lumbar vertebrae, and on the body of the fourth lumbar vertebra divides into the two 
common iliac arteries. The aorta is divided into three portions, an arch extend- 
ing from its origin to the lower body of the fifth thoracic vertebra, the thoracic 
aorta from the lower border of the fifth thoracic to the aortic opening in the dia- 
phragm, and the abdominal aorta from the aortic opening in the diaphragm to the 
body of the fourth lumbar, its point of division into the common iliacs. Imme- 
diately above the aortic valves the arch gives off two vessels, the right and left 
coronary arteries, which supply the heart. The transverse portion of the arch, as 
a rule, gives off thi-ee vessels, the brachio-cephalic (innominate), the left common 
carotid, and the left subclavian. The brachio-cephalic (“arm-head”) is a short 
vessel, an inch and a half in length, extending from the transverse portion of 
the arch to the right sterno-clavicular articulation, where it divides into the right 
common carotid and right subclavian. Thus the right subclavian and right carotid 
differ in their origin and length from the left subclavian and left carotid. The 
common carotid on both sides terminates at the superior border of the thyroid 
cartilage, by dividing into.the internal and external carotids, and, as a rule, the 
common carotids have no other branches. The external carotid terminates a lit- 
tle below the condyle of the jaw by dividing into the temporal and internal max- 
illary. The external gives off in addition to its two terminal branches mentioned, 
the superior thyroid, the lingual, the facial, the occipital, the posterior auricular, 
and the ascending pharyngeal. Speaking broadly, it supplies the structures of 
the neck and the face (with the exception of the contents of the orbit and the 
integument of the forehead), the scalp, and the greater portion of the dura mater. 
These branches of the external carotid again subdivide into branches which will be 
studied in detail later. The internal carotid which begins at the superior border 
of the thyroid cartilage passes up to and through the carotid canal in the petrous 
portion of the temporal bone, enters the cranial cavity, and breaks up into 
branches which supply the greater part of the brain and contents of the orbit; 
the vertebral, a branch of the subclavian, as we shall find, assists the carotid in 
supplying the brain. 
The subclavian artery begins on the right side from the brachio-cephalic, on 
the left from the arch of the aorta, and passes outward to the lower border of the 
first rib, where the vessel changes its name and becomes the axillary. The sub- 
clavian is divided into three portions according to its relation to the scalenus 
anterior. It gives off as branches the thyroid axis, the vertebral, the internal 
mammary, and the superior intercostal. The axillary begins at the lower border of 
the first rib and extends to the lower border of the axillary space, where the ves- 
sel changes its name and becomes the brachial. The axillary is divided into three 
parts according to its relation to the pectoralis minor muscle, which is in front of 
it. The axillary gives off the superior thoracic, the acromio-thoracic, the long 
thoracic, the alar thoracic, the subscapular, the anterior and posterior circumflex. 
The brachial extends from the lower border of the axillary space to a point a 
half inch below the elbow, where it divides into the radial and ulnar. It gives 
off in its course the superior profunda, muscular, nutrient, inferior prof unda, and 382 
THE BLOOD-VASCULAR SYSTEM, 
anastomotica magna. The radial extends from the point of bifurcation of the 
brachial to the palm of the hand, where it forms the deep palmar arch, anasto- 
mosing with the deej) branch from the ulnar. It gives off in the forearm the 
radial recurrent, the muscular, the anterior carpal, and the superjicialis voice ; in 
the wrist, the posterior carpal, the metacarpal, the dorsalis indicts, and dorsalis 
pollicis; in the hand, the princeps pollicis, the radialis indicis, the perforating, 
and interosseous. The ulnar begins a half inch below the elbow, and like the 
radial extends into the hand, terminating in the superficial palmar arch, anasto- 
mosing with the superficialis volse. In the forearm it gives otf the anterior ulnar 
recurrent, the posterior idnar recurrent, the interosseous, which divides into an 
anterior and posterior branch, and muscular. In the wrist it gives off anterior 
and posterior carpal branches, and in the hand the deep communicating branch and 
the digital. 
Returning to the aorta, we find that the thoracic portion, which begins at the 
lower border of the fifth thoracic vertebra and terminates at the aortic opening in 
the diaphragm, gives off branches as follows : pericardial, bronchial, cesophageal, 
posterior mediastinal, and intercostal—these branches supplying the walls and 
contents of the thorax, with the exception of the heart-substance, which is sup- 
plied by the coronary arteries. 
The abdominal aorta begins at its opening in the diaphragm, and terminates on 
the body of the fourth lumbar vertebra by dividing into the common iliacs. It 
gives otf as branches the phrenic, the coeliac axis, the superior mesenteric, the renal, 
the suprarenal, the spermatic, the inferior mesenteric, the lumbar, and the sacral 
arteries. These vessels as a group supply the walls of the abdominal cavity and 
the viscera contained within that cavity. The common iliac begins on the body 
of the fourth lumbar vertebra and extends to the intervertebral substance between 
the last lumbar vertebra and the sacrum. Here it divides into the internal and 
external iliac arteries. The common iliac gives off no branches of importance in 
its course. 
The internal iliac extends from the intervertebral substance between the last 
lumbar vertebra and sacrum to the upper margin of the great sacro-sciatic notch, 
where it divides into an anterior and posterior trunlc, the anterior giving off as 
branches the superior vesical, the middle vesical, the inferior vesical, the middle 
hemorrhoidal, the obturator, the internal pudic, and the sciatic; also, the uterine 
and vaginal in the female. The posterior trunk gives off the ilio-lumbar, the 
lateral sacral, and the gluteal. As a group, the branches of the internal iliacs supply 
the walls and viscera of the pelvis. In addition to this, the gluteal, sciatic, and 
obturator supply the buttock and back part and internal surface of the thigh, and 
the internal pudic supplies the perineum and external organs of generation. The 
external iliac extends from the termination of the common iliac to the inguinal 
(Poupart’s) ligament. Here it changes its name and becomes the femoral. In its 
course it gives off two vessels, the deep epigastric and circumflex iliac. 
The femoral begins at the inguinal (Poupart’s) ligament and extends to the 
femoral opening in the adductor magnus muscle. Here it passes into the popli- 
teal space and becomes the poplitecd.. In its course it gives off as branches the 
superficial epigastric, the superficial external pudic, the superficial circumflex iliac, 
the deep external pudic, the profunda, the muscular, and the anastomotica magna. 
The profunda, which is a large trunk, gives off as branches the external circumflex, 
the internal circumflex, and the three perforating arteries. The femoral with its 
branches supplies the thigh. The popliteal extends from the opening in the 
adductor magnus muscle to the lower border of the popliteus muscle, and here 
divides into the anterior and posterior tibial arteries. In its course it gives off 
muscular branches, superior and inferior cutaneous, superior external articidar, 
superior internal articular, azygos articidar, inferior external articular and inferior 
internal articular arteries, which as a group supply the tissues in the popliteal 
space and the knee-joint. 
The anterior tibial begins at the lower border of the popliteus muscle, per- THE ARTERIES. 
383 
forates the interosseous membrane, and passes to the anterior surface of the leg, 
and thence down to the bend of the ankle, where it changes its name to dorsalis 
pedis. In its course in the leg it gives off as branches the recurrent tihial, mus- 
cular, internal malleolar, and external malleolar arteries. The dorsalis pedis 
extends from the bend of the ankle to the back part of the first interosseous 
space, where it divides into the dorsalis hallucis and communicating. It gives off 
as branches the tarsal, the metatarsal, and the interosseous, which supply the dor- 
sum of the foot and toes, and the communicating, which anastomoses with the 
external plantar, thus completing the plantar arch. 
The posterior tihial passes down the back of the leg to the concavity between 
the heel and inner ankle, where it divides into the internal and external plantar 
arteries. In its course it gives off as branches the peroneal, anterior peroneal, 
muscular, nutrient, communicating, and internal calcanean arteries, which as a group 
supply the back of the leg and heel. The internal plantar begins at the point of 
division of the posterior tibial, and runs forward along the inner side of the great 
toe, .which it supplies. The external plantar passes forward in the sole of the 
foot, and forms by anastomosing with the communicating branch of the dorsalis 
pedis, the plantar arch, which gives off posterior perforating, digital, and anterior 
perforating branches, and supplies the sole of the foot and the toes. 
The student is strongly advised to draw a rough longitudinal sketch of the 
entire arterial system following the syllabus given above. This sketch should 
show the origin, course, termination, and branches of each vessel; as later the 
vessels are studied in detail, sketches of special portions of the arterial system, 
as the circle of Willis, the vessels in the triangles of the neck, the axillary space, 
Scarpa’s triangle, the popliteal space, etc., should be made ; also sketches of cross- 
sections of the trunk, neck, and upper and lower extremities at different levels, 
showing the position of the vessels, and their relation to surrounding structure. 
Such a method will materially aid the student in the study of the arteries in the 
dissecting-room and on the living model. 
THE AORTA. 
The aorta is the main trunk of the systemic system. It begins at the left ven- 
tricle and terminates on the body of the fourth lumbar vertebra by dividing into 
the common iliacs. It is divided anatomically into three portions, the arch, the 
thoracic aorta, and the abdominal aorta. The arch of the aorta extends from the 
left ventricle to the lower border of the body of the fifth thoracic vertebra; the 
thoracic aorta from this point to the aortic opening in the diaphragm ; the abdomi- 
nal aorta from the aortic opening in the diaphragm to the termination of the ves- 
sel on the body of the fourth lumbar vertebra. The aorta is divided by some 
anatomists into an ascending aorta, an arch, and a descending aorta, the ascend- 
ing aorta corresponding to the ascending portion of the arch in the description 
which will be followed here, the arch corresponding to the transverse portion of 
the arch, and the descending aorta beginning at the lower border of the fourth 
dorsal vertebra, and, therefore, including the descending portion of the arch of 
the division here adopted. 
THE ARCH OF THE AORTA 
The arch (Fig. 440) is divided into three portions : an ascending, a transverse, 
and a descending portion. 
The Ascending Portion of the Arch.— Origin : the left ventricle opposite the 
lower border of the third costal cartilage and behind the sternum. Course, upward 
and to the right to the upper border of second costal cartilage. Termination : here 
the ascending portion bends backward and to the left, and becomes the transverse 
portion of the arch. 384 
THE BLOOD-VASCULAR SYSTEM. 
LEFT AURICU- 
LAR APPENDIX 
S—-LEFT 
U VENTRICLE 
RIGHT W 
VENTRICLE^ 
BRONCHIAL 
TUBES 
RIGHT 
AURICLE 
Fig. 440. Arch of the aorta and its branches. (Testut.) 
Relations. 
Pulmonary artery. 
Appendix of right auricle 
Pericardium and sternum. 
In front. 
At the right. 
At the left 
Superior cava and right Ascending portion of Pulmonary artery, 
auricle. arch. 
Behind. 
Root of right lung. 
The Transverse Portion of the Arch.— Origin, on a level with the upper border 
of second costal cartilage, at which point the aortic arch turns backward and to 
the left. Termination, at the lower border of the fourth thoracic vertebra. 
Relations. 
Above. 
Left brachio-cephalic vein. 
Brachiocephalic artery. 
Left carotid. 
Left subclavian. 
In front. Behind. 
Trachea. 
Left lung and pleura. Transverse (Esophagus. 
Left pneumogastric nerve. portion Thoracic duct. 
Left phrenic nerve. of arch. Left recurrent laryngeal 
nerve. THE ARTERIES. 
385 
Below. 
Bifurcation of pulmonary artery. 
Left recurrent laryngeal nerve. 
Root of left lung. 
The Descending Portion of the Arch,—This is that portion of the aorta in front 
of the body of the fifth dorsal vertebra and the intervertebral disc above it. 
Relations, 
In front. 
Pleura. 
Root of left lung. 
Right side. 
Left side. 
Pleura. 
(Esophagus. 
Thoracic duct. 
Descending portion 
of arch. 
Behind. 
Body of fifth dorsal vertebra. 
The branches of the arch are the right and left coronary arteries, which arise 
from just above the anterior and left flaps of the aortic valve; the brachio- 
cephalic, the left common carotid, and the left subclavian from the transverse 
portion of the arch. 
Varieties.—The position of the vessel varies. It may reach as high as the top 
of the sternum, or its summit may be as low as the fifth dorsal vertebra; the 
failure of normal development of the aortic arches of the foetus may result in the 
persistence of the ductus arteriosus ; there may be persistence of a septum within 
the vessel, dividing it into two tubes; the presence of a right instead of a left 
aortic arch, this last being sometimes accompanied with a transposition of the 
viscera; the presence of a double aortic arch, one on the left, the other on the 
right, these passing backward, embracing the oesophagus, and uniting to form a 
single thoracic aorta. The number of branches given off from the transverse por- 
tion of the arch varies from one to six ; a single trunk may be given off which 
then divides into the great vessels of the neck and upper extremities. There may 
be two branches, a right and left brachio-cephalic, or two branches, a right sub- 
dividing into the right subclavian, right common carotid, and left common carotid, 
the other branch being the left subclavian. Four vessels may be given off—right 
subclavian, right carotid, left carotid, and left subclavian ; or four vessels may 
exist in which the usual brachio-cephalic, the left carotid, and left subclavian are 
present, but in which the left vertebral arises as a separate trunk from the arch. 
Five vessels may exist in a case like the above in which the brachio-cephalic is 
absent, and where we find a right subclavian, right common carotid, left common 
carotid, left vertebral, and left subclavian arising as separate branches of the 
arch. Cases of six branches are the same as the above, except that the right ver- 
tebral is added as a separate trunk. The surgical anatomy is of special interest 
in the study of aneurism, which occurs more frequently in the aorta than in any 
other artery. 
The relations of the arch of the aorta to surrounding structures should be 
studied with reference to the effects of the pressure produced by aneurism upon 
them, and the resulting symptoms. Aneurism of the ascending portion of the 
arch may by pressure produce absorption of the costal cartilages, sternum, and 
ribs, and present itself as a pulsating tumor to the right of the sternum, event- 
uallv rupturing and producing death. Aneurism of the transverse portion may 
produce pressure on the oesophagus, producing difficult deglutition, and simu- 
lating stricture of the oesophagus. Such an aneurism may also produce pressure 
on the trachea and bronchi, the thoracic duct, and the great veins within the 386 
THE BLOOD-VASCULAR SYSTEM. 
thorax, and interfere with the normal function of these structures. An interest- 
ing symptom is hoarseness and loss of voice, due to pressure on the recurrent 
laryngeal nerve. 
Branches of the Ascending Portion of the Arch.—The coronary arteries are two 
in number. The right coronary arises from the aorta above the right (anterior) 
flap of the aortic valve; it winds to the right in the groove between the right 
auricle and ventricle, until it reaches the septum between the right and left ven- 
tricles posteriorly. Here it divides into two branches, one continuing in the 
groove between the left auricle and ventricle ; the other passing downward in the 
groove between the ventricles to the apex of the heart. 
The left coronary arises from above the left segment of the aortic valve, 
passes forward and to the left behind the pulmonary artery, and divides opposite 
the septum between the right and left ventricles anteriorly into two branches, one 
descending in the groove between the ventricles to the apex of the heart, the 
other running to the left and backward in the groove between the left auricle and 
the left ventricle. The coronary arteries supply the heart-muscle, and send small 
branches to the contiguous portions of the aorta and pulmonary artery. 
The Branches of the Transverse Portion of the Arch.—These are the brachio- 
cephalic, the left common carotid, and the left subclavian. 
THE BRACHIO CEPHALIC ARTERY. 
The brachio-cephalic (innominate) artery is a short trunk of about an inch 
and a half in length, and is the first branch of the transverse portion of the arch. 
Origin, from the transverse portion of the arch opposite the upper border of the 
second costal cartilage. Course, upward and to the right. Termination, at the 
sterno-clavicular articulation by dividing into the right common carotid and right 
subclavian. 
Relations. 
Sternum 
In front. 
Sterno-hyoid and sterno-thyroid muscles. 
Left innominate and left inferior thyroid veins. 
Right side. 
Left side. 
Right brachio-cephalic vein. „ ~ , .. Left carotid. 
i , r, . Bracnio-cepnalic T n n n 
Right pneumogastnc nerve. . Lett interior thyroid vein. 
o i o o vt.PI'TT' , * 
Pleura. y‘ Trachea. 
Behind. 
Trachea. 
Variations.—The brachio-cephalic may be absent, the right common carotid 
and subclavian springing directly from the aorta. It may be longer or shorter 
than usual—less than an inch, or more than twro inches in length. 
Surgical Anatomy (Fig. 442).—The brachio-cephalic may be the site of 
aneurism, and from its deep position produce pressure-symptoms resembling 
aneurism of the arch of the aorta—i. e., pressure on the trachea, recurrent laryn- 
geal, oesophagus, roots of the lungs, and the great vessels. The brachio-cephalic has 
been ligated for aneurism of the carotid and subclavian, but the results have not 
been encouraging ; and although the operation is not a standard surgical procedure 
and one rarely performed, the description of the dissection necessary to expose the 
vessel for ligation will be of value in fixing in the student’s mind the relation of 
surrounding structures, and will therefore be given here. The subject is placed 
on the table with a block beneath the shoulder, so that the head and neck fall 
backward, and an assistant draws the right upper extremity downward so as to THE ARTERIES. 
387 
shaded; on sm/are thoracic vertebra. The upper surface of the lower segment is shown. On the left side the muscles are 
HEAD OF 
RIGHT 
HUMERUS 
CORACOBRACHIALIS 
I AND BICEPS 
RIGHT SUBCLAVIAN ARTERY 
CEPHALIC VEIN 
PNEUMOGASTRIC NERVE 
/RIGHT BRACHIOCEPHALIC VEIN 
/sternohyoid 
/PHRENIC NERVE 
/INTERNAL MAMMARY ARTERY 
/ SUBCLAVIUS 
INFERIOR THYROID VEIN 
STERNOTHYROID / 
BIVENTER AND 
COMPLEXUS 
SEMISPINALIS AND 
MULTIFIDUS 
BRACHIOCEPHALIC 
ARTERY! 
' THIRD ' 
THORACIC 
. VERTEBRA , 
*>■ V 
SPINE OF SECOND] 
THORACIC VERTEBRA 
LEFT CAROTID 
ARTERY \ 
PNEUMOGASTRIC NERVE 
> 
o 
X 
CL 
left subclavian artery 
LEFT SUBCLAVIAN ARTERY 
SUPRASCAPULAR ARTERY 388 
THE BLOOD-VASCULAR SYSTEM, 
draw the clavicle downward, and expose as much of the vessel as possible. An 
incision four inches in length is made on the inner border of the sterno-cleido- 
mastoid, extending to the sterno-clavicular articulation. A second incision of 
the same length is made over the clavicle parallel with it, meeting the first 
incision. These incisions divide the skin, superficial fascia, and platysma myoid 
HYPOGLOSSAL NERVE' 
EXTERNAL CAROTID 
ARTERY 
FACIAL ARTERY^ 
GREAT HORN OF HYOID^ 
v SU B M AXI LLAR Y GLAND 
EXTERNAL JUGULAR VEIN_ 
STERNO-CLEIDO- 
MASTOIDEUS “ 
STYLO-HYOIDEUS AND 
DIGASTRICUS 
STERNO-CLEIDO- 
MASTOIDEUS " 
THYROID GLAND J 
PNEU MO GASTRIC NERVE 
AND RECURRENT BRANCH 
INTERNAL JUGU LAR 
yHasSS^^B 
-DESCENDENS HYPO- 
GLOSSI NERVE 
OMOHYOIDEUS 
MEDIAN NEHVt 
RECTO R ALIS MAJOR 
"STERNO-THYROIDEUS 
STERNO-HYOIDEUS 
-TRANSVERSE JUGULAR 
VEIN 
'axillary VEIN 
« PI I 
PECTOHALIS MINOR 
DELTOIDEUS 
ANTERIOR THORACIC NERVES 
SUBCLAVIAN ARTERY 
I NTER COSTA LIS INTERNUS 
STERNUM 
INTERNAL MAMMARY ARTERY 
PLEURA 
PECTORALIS MAJOR 
Fig. 442.—Surgical relations of the lingual, external carotid, common carotid, brachio-cephalic, subclavian, 
and internal mammary arteries. (Kocher.) 
muscle, and expose to view the sterno-cleido-mastoid. This should be divided 
completely across at a point one and a half inches above the sternum, and the 
lower part turned downward and held out of the way. The sterno-thyroid and 
sterno-hyoid muscles come now into view, and are divided in the same way. 
This usually exposes the inferior thyroid veins, which are either carefully pushed 
out of the way, or are ligated at two points, and divided. The common carotid is 
now exposed, and followed downward until the brachio-cephalic is reached. The 
left brachio-cephalic vein crosses the artery in the lower half of its course, the THE A UTEBIES. 
389 
right brachio-cephalic vein and the pneumogastric nerve are to the right of the 
vessel, and the pleura and trachea are behind. In passing an aneurism-needle it 
is best passed from the right to the left behind the vessel, care being taken to avoid 
injury to the pneumogastric nerve, the brachio-cephalic veins, and the pleura. 
Branches.—ln addition to the terminal branches, the right common carotid 
and right subclavian, the brachio-cephalic occasionally gives off a branch, the 
thyroidea into,, which passes upward on the surface of the trachea to the isthmus 
of the thyroid gland, and the occasional presence of this branch should be 
remembered in the operations of removal of the thyroid gland, and in low 
tracheotomy. 
The common carotid, arteries (Fig. 443) differ upon the two sides. The right 
takes its origin from the brachio-cephalic, the left from the arch of the aorta; the 
left is, therefore, the longer of the two. In the neck the common carotids are so 
nearly alike that one description will answer for both. It will be necessary, how- 
ever, to describe that portion of the left carotid which extends from the arch 
to the sterno-clavicular articulation. 
The Left Carotid Artery in the Thorax. 
This portion resembles somewhat the brachio-cephalic artery in length and in 
its relation to surrounding structure. 
Relations. 
In front. 
Sternum. 
Sterno-hyoid and sterno-thyroid. 
Left brachiocephalic vein. 
Right side. Left side. 
Left carotid Left pneumogastric nerve. 
Brachio-cephalic artery. in Left subclavian. 
thorax. Artery. 
Behind. 
Trachea. 
(Esophagus. 
Thoracic duct. 
THE COMMON CAROTIDS IN THE NECK. 
Origin, opposite the sterno-clavicular articulation from the brachio-cephalic 
on the right side, and from the thoracic portion of the common carotid on the left. 
Course, upward and outward in a line drawn between the sterno-clavicular 
articulation and a point midway between the angle of the jaw and the mastoid 
The vessel is covered by the steino—cleido—mastoid muscle, the inner 
border of which is a good guide to its course. lermination :at the level of the 
upper border of the thvroid cartilage, the common carotid divides into the inter- 
nal and external carotids. 
Relations. 
Integument and superficial fascia. 
Platysraa and deep cervical fascia. 
Sterno-mastoid muscle. 
Sterno-hyoid, sterno-thyroid, omo-hyoid muscles. 
Lescendens noni nerve. 
Sterno-mastoid artery. 
Superior and middle thyroid veins. 
Anterior jugular vein. 
In front. 390 
THE BLOOD-VASCULAR SYSTEM. 
SUPRA- 
SCAPULAR/ 
Fig. 443.—Right subclavian and carotid arteries. The vertebral artery is seen threading the costo-trans 
verse processes of the vertebrae. (Testut.) 
External. 
Trachea. 
Thyroid gland. 
Recurrent laryngeal nerve. 
Inferior thyroid artery. 
Larynx and pharynx. 
Internal. 
Pneumogastric nerve. 
Internal jugular vein. 
Common 
carotid 
in neck. 
Behind. 
Longus colli. 
Rectus capitis anterior major. 
Sympathetic nerve. 
Recurrent laryngeal nerve. 
Inferior thyroid artery. 
Variations.—The right common carotid sometimes springs directly from the 
arch of the aorta; sometimes the left common carotid springs from a left brachio- 
cephalic artery ; the common carotid is sometimes absent, the internal and external 
carotids springing directly from the arch of the aorta or from a brachio-cephalic 
artery. In some cases it divides above or below the usual point, low down in the 
neck or as high as or higher than the hyoid bone. 
Surgical Anatomy (Fig. 442).—The common carotid can be ligated in any part 
of its course; the best point to select is about the level of the cricoid cartilage 
and above the omo-hyoid muscle, because here the vessel is more accessible than 
in the lower part of its course. To expose the vessel in the upper part of its 
course an incision three inches in length is made along the inner border of the 
sterno-cleido-mastoid muscle, the centre of the incision being opposite the cricoid 
cartilage. The incision divides the skin, superficial fascia, platysma myoid, and 
the anterior layer of the deep fascia ; the sterno-cleido-mastoid muscle is drawn to 
the outer side. The sterno-mastoid artery is usually divided, but this is of no THE All TERIES. 
391 
Fig. 444.—Horizontal section through the body ot the seventh cervical vertebra. rlhe upper surface of the lower segment is shown. The lack of bilateral symmetry is 
largely due to the difference in the level of the shoulders—a not unusual condition. (After Braune.) 
ANGLE OF SCAPULA 
/COMMON CAROTID ARTERY 
BRACHIAL PLEXUS 
°> 
£ z 
>< 
✓ INTERNAL JUGULAR VEIN 
,PNEUMOGASTRIC NERVE 
-PHRENIC NERVE 
'STERNOHYOIDEUS 
INF. ARTICULAR PROCESS OF 
SEVENTH CERVICAL VERTEBRA 
SEVENTH 
CERVICAL 
VERTEBRA 
trachea) 
SUPERIOR THYROID ARTERY^ 
INFERIOR THYROID ARTERY^ 
VERTEBRAL ARTERY^ 
BRACHIAL PLEXUS- 
/ 
TRANSVERSALIS COLLI ARTERY 392 
THE BLOOD-VASCULAR SYSTEM. 
importance ; the sheath is exposed and opened, care being taken not to injure the 
descendens hypoglossi, which is usually in front of the sheath. The internal 
jugular vein is external, sometimes overlaps the vessel; the pneumogastric nerve 
is external and behind the vessel. In passing an aneurism-needle care should be 
taken to avoid these structures, which is best done by passing the needle from 
without behind and inward. The vessel lies deeply situated in the lower part of 
its course, and the operation to expose it is more difficult; an incision four inches 
in length is made from the sterno-clavicular articulation upward along the inner 
border of the sterno-cleido-mastoid muscle. This incision divides the skin, super- 
ficial fascia, platysma, and deep fascia. The sterno-cleido-mastoid is turned to 
the outer side ; this exposes the sterno-hyoid and sterno-thyroid muscles; these 
are drawn to the inner side, and the sheath of the vessel is exposed. The inter- 
nal jugular overlaps and is external to the vessel; the pneumogastric nerve is 
external and behind. These structures are to be avoided in passing the aneurism- 
needle. After ligation of a common carotid, collateral circulation is soon estab- 
lished through the free anastomoses which exist between the branches of the 
internal and external carotids of the opposite side, and the anastomoses which 
exist between the branches of the external carotid of the side operated upon and 
the branches of the subclavian. 
Branches.—The common carotid, as a rule, does not give off any branches in 
its course; in rare cases it gives off a superior or an inferior thyroid or the ver- 
tebral artery. The terminal branches are the internal carotid and the external 
carotid. 
The External Carotid Artery (Figs. 443, 445). 
Origin: the external carotid begins as one of the terminal branches of the 
common carotid opposite the superior border of the thyroid cartilage. Course :it 
passes upward and outward to a point between the condyle of the jaw and the 
external auditory meatus. Termination: it terminates in the substance of the 
parotid gland by dividing into the temporal and the internal maxillary arteries. 
Relations. 
In front 
Integument, superficial fascia, platysma and deep fascia. 
Hypoglossal nerve. 
Lingual and facial veins. 
Digastric and stylo-hyoid muscles. 
Parotid gland. 
Facial nerve. 
External 
Hyoid bone. 
Pharynx. 
Inferior laryngeal nerve. 
Internally. 
carotid 
artery. 
Superior laryngeal nerve. 
Stylo-glossus and stylo-pharyngeus muscles. 
Glosso-pharyngeal nerve. 
Parotid gland. 
Behind. 
Variations.—The external carotid may arise above or below its usual point— 
i. e., opposite the superior border of the thyroid cartilage. Sometimes the artery 
arises as a branch from the aortic arch. Cases are found where the external 
carotid is altogether absent, the common carotid not dividing into the internal 
and external carotids, but supplying from a common trunk the branches usually THE ARTERIES. 
393 
supplied by these vessels. Variations in the branches of the external carotid are 
very often met with, and will be described in connection with each branch 
respectively. 
Surgical Anatomy (Figs. 442-446).—T0 ligate the external carotid in the 
lower half of its course, an incision should be made three inches in length, 
beginning an inch below the superior border of the thyroid cartilage, and extend- 
ing upward along the inner border of the sterno-cleido-mastoid muscle. This 
incision should divide the skin, superficial fascia, platysraa myoid muscle, and 
deep fascia ; the sterno-cleido-mastoid is drawn to the outer side, and the vessel 
exposed. The vessel is very superficially situated, and the operation is not 
difficult. To expose the vessel in the upper half of its course, an incision should 
be made about three inches in length along the inner border of the sterno-cleido- 
INTERNAL 
MAXILLARY 
POSTERIOR ’ 
AURICULAR 
OCCIPITAL^ 
Fig. 445.—The external and internal carotid arteries. The hypoglossal nerve, the digastric and stylo- 
hyoid muscles, and the internal jugular vein are to be noted, (iestut.) 
mastoid, beginning opposite the hyoid bone and extending upward. This incision 
should divide the skin and superficial fascia, platysma myoid muscle, and the deep 
fascia. The posterior belly of the digastric muscle and the stylo-hyoid muscles 
are found crossing the artery, and above these is seen the lower border of the 
parotid gland. The digastric and stylo-hyoid muscles are drawn downward, 
and the border of the gland upward, and the vessel is then exposed to view. 
Branches.—The external carotid, in addition to its two terminal branches, the 
internal maxillary and temporal, gives off three, anterior branches, the superior 
thyroid, the lingual, and facial; two posterior branches, the occipital and post- 
auricular; and one internal branch, the ascending pharyngeal. Although the 
external carotid in the majority of dissections gives off the branches as described, 
variations are very common. 
Superior Thyroid (Fig. 443).— Origin : from the anterior surface of the exter- 394 
THE BLOOD-VASCULAB SYSTEM. 
nal carotid below the hyoid bone. Course and termination ; it runs at first upward 
and inward, and then curves downward and inward beneath the omo-hyoid, 
sterno-hyoid, and sterno-thyroid muscles to the upper portion of the lateral lobe 
of the thyroid gland, to which it is distributed. 
Relations.—The superior thyroid at its origin is superficially situated and 
covered by the skin, superficial fascia, platysma, and deep fascia ; before it reaches 
'GREAT AURICULAR 
NERVE 
-SPINAL ACCESSORY 
NERVE 
EXTERNAL JUGULAR 
VEIN 
"DESCENDENS HYPO- 
GLOSS! NERVE 
INTERNAL JUGULAR VEIN 
HYPOGLOSSAL NERVE* 
GREAT HORN OF HYOID^ 
* STE R NO-CLEIDO- 
MASTOIDEUS 
SUPERIOR LARYNGEAL 
NERVE 
EXTERNAL 
ARTERY 
SUPERIOR 
ARTERY 
/ NERVE 
TRANSVERSALIS COLLI 
- ARTERY 
EXTERNAL JUGULAR 
VEIN 
SCALENUS MEDIUS 
-"FIRST RIB 
PHRENIC NERVE 
SCALENUS AN- 
TERIOR 
.^^TRAPEZIUS 
STER N O-C LEI DO-_ 
MASTOIDEUS 
-O MO-HYOIDEUS 
SUBCLAVIAN. 
ARTERY 
BRACHIAL- 
PLEXUS 
-PLATYSMA 
Fig. 446.—Surgical relations of the external carotid, lingual, facial, occipital, subclavian, and transversalis 
colli arteries. (Kocher.) 
the thyroid gland it becomes more deeply situated by passing beneath the omo- 
hyoid, sterno-hyoid, and sterno-thyroid vessels. 
Varieties.—The superior thyroid is sometimes given off as a branch of the 
common carotid, and sometimes is a branch of a trunk from the external carotid, 
common to it and the lingual or facial. 
Surgical Anatomy.—The superior thyroid can be ligated close to its origin 
from the external carotid through the same incision described in ligating the 
external carotid in the lower part of its course. This operation is sometimes 
done to limit the blood-supply of an enlarged thyroid gland, or in cases of 
exophthalmic goitre. The artery is ligated in the operation of extirpation of the 
thyroid. THE ARTERIES. 
395 
Branches.—The superior thyroid gives off branches to the muscles with which 
it is in contact, and its terminal branches to the thyroid gland; and in its course 
gives off usually four branches, the hyoid, the sterno-mastoid, the superior laryn- 
geal, and the crico-thyroid. The hyoid, runs along the lower border of the hyoid 
bone. The sterno-mastoid runs outward and downward to the sterno-mastoid mus- 
cle, which it supplies. This vessel is often divided in the many operations on the 
side of the neck in which the incision is along the inner border of the sterno-mas- 
toid, as in removing tubercular glands of the neck, in the operation for ligating 
the common carotid, etc. The superior laryngeal accompanies the superior laryn- 
geal nerve in its distribution to the interior of the larynx, passing with the nerve 
through the thyro-hyoid membrane, and supplying the mucous membrane and 
muscles of the larynx. The crico-thyroid artery runs inward on the surface of 
the crico-thyroid membrane. 
The Lingual Artery (Fig. 447).—Origin : from the external carotid above the 
superior thyroid and a little below the hyoid bone. Course and termination : the 
lingual runs along the upper border of the great cornu of the hyoid, then leaves 
the bone, and passes to the base of the tongue, and runs along the under surface 
of the tongue, terminating as the ranine artery. 
Relations.—The artery is at first superficial, then passes beneath the digastric 
muscle and hyoglossus muscles, and has in front of it the hypoglossal nerve; 
INTERNAL 
CAROTID' 
Fig. 447.—Arteries and veins of the tongue, viewed from the right side. (Testut.) 
later it is situated in the root of the tongue between the hyoglossus and genio- 
hyoglossus muscles; it then as the ranine becomes again superficial, being 
covered only by the mucous membrane of the inferior surface of the tongue. 
Varieties.—The lingual artery is sometimes a branch from a trunk of the 
external carotid common to it and the facial, or to it and the superior thyroid, 
or the three vessels may arise from a common trunk. 
Surgical Anatomy (Figs. 442, 446).—The lingual artery is often injured in 
cases of cut throat. It may require ligation also as a preliminary step in removal 
of the tongue for carcinoma. The vessel can be ligated at its point of origin from 
the external carotid by the incision described to expose that vessel in the lower 
part of its course, or it can be ligated where the vessel runs parallel with and just 
above the hyoid bone and covered by the hyoglossus muscle. In order to 
expose the vessel in this position, a curved incision should be made, beginning a 
little below the body of the jaw and an inch from the median line, the convexity 
of the incision downward, reaching the level of the hyoid bone, and the incision 
terminating below the angle of the jaw. The skin, superficial fascia, platysma, 396 
THE BLOOD-VASCULAR SYSTEM. 
and deep fascia are divided, and the submaxiilary gland is exposed and drawn 
upward. Beneath the submaxiilary gland the digastric tendon is exposed, running 
upward in each direction to its anterior and posterior belly respectively. Above 
this tendon is seen the hypoglossal nerve ; between the nerve and tendon the 
hyoglossus muscle is exposed. The fibres of this muscle are separated, and, 
running parallel with the nerve but beneath it, the lingual artery comes into view. 
The ranine artery may be ligated by dividing the mucous membrane of the lower 
surface of the tongue parallel with and external to the raphe. 
Branches of the lingual are the hyoid, dorsal lingual, sublingual, and ranine. 
The hyoid runs along the upper border of the hyoid bone. The dorsal lingual 
runs upward to the mucous membrane of the dorsum of the tongue, which it 
supplies. The sublingual supplies the sublingual gland. The ranine gives off 
branches to the muscles of the tongue, and runs in a tortuous course to its tip, 
being in the last part of its course superficial, covered only by the mucous mem- 
brane. 
The Facial Artery (Fig. 448).—Origin : from the anterior surface of the exter- 
nal carotid above the hyoid bone. Course and termination : the vessel passes 
upward and forward to the inferior border of the lower jaw. In its course it is 
-SUPRAORBITAL 
OCCIPITAL 
Fig. 448.—Superficial arteries of the head. (Testut.) 
covered by the submaxiilary gland and partly surrounded by the gland, so that 
the vessel occupies a groove on its deep surface. The vessel winds over the body 
of the lower jaw in front of the masseter muscle, marking the bone in this posi- 
tion by a shallow groove. It then passes upward and forward on the face to the 
side of the nose, and from the side of the nose upward to the angle of the eye, 
where it terminates as the angular artery. THE ARTERIES. 
397 
Relations.—At its point of origin the vessel is superficial, being covered by the 
skin, superficial fascia, platysma, and deep fascia ; it then passes beneath the stylo- 
hyoid and digastric muscles and the snbmaxillary gland, and is deeply situated. 
At the border of the jaw the vessel again becomes superficial, and its pulsations 
can be readily felt in front of the masseter. In the face it passes through the 
muscle-fibres of the facial muscles. 
Variations.—The variation most commonly met with is the occurrence of a 
trunk from the external carotid, common to the facial and lingual arteries. 
Surgical Anatomy (Fig. 446).—The facial can be ligated at its origin from the 
external carotid, or at its point of crossing the lower jaw. In operations for the 
removal of the snbmaxillary gland the fact should be remembered that the artery 
occupies a groove on its internal or deep surface, and is in a position to be injured. 
The course of the branches of the facial should be studied in the many operations 
on the face. 
Branches.—The branches of the facial are divided into two sets, a cervical set 
and a facial set. 
In the cervical region the facial gives off the ascending palatine artery, the 
tonsillar, the glandular, the submental, and muscular. The ascending palatine 
passes to the outer side of the pharynx, which it supplies ; it also sends a branch 
to the soft palate, and anastomoses with the descending palatine artery, a branch 
of the internal maxillary. The tonsillar is a branch to the tonsil and tongue. The 
glandular are branches given off to the submaxillary gland. The submental is a 
large branch which runs along the lower border of the jaw to the chin; here the 
vessel gives off terminal branches, which wind over the jaw, and supply the tissues 
of the lower lip. Muscular branches are given off to the muscles with which the 
vessel is in contact. The facial branches are the inferior labial, the coronary, the 
lateral nasal, the angular, and muscular. The inferior labial runs parallel witli 
the body of the jaw forward to the chin; it supplies the tissues of the chin and 
lower lip. The coronary arteries are given off at the angle of the mouth, and 
run, one in the tissues of the lower lip, the other in the tissues of the upper lip, 
in close contact with the mucous membrane. The lateral nasal supplies the ala 
of the nose. The angular is the terminal branch of the facial. It ascends to the 
inner angle of the eye, and supplies the structures in this position, anastomosing 
with the infra-orbital, and with the nasal branch of the ophthalmic artery. 
The Occipital Artery (Fig. 448).—Origin: the occipital artery arises from the 
external and posterior surface of the external carotid, opposite to the facial, at 
a point a little above the level of the hyoid bone. Course and termination :it 
winds upward and backward to the mastoid portion of the temporal bone, occupy- 
ing a groove on its inferior surface. The vessel is here covered by the digastric 
and stylo-hyoid muscles, and crosses the internal carotid, internal jugular vein, 
and the pneumogastric nerve ; it then continues upward and backward beneath 
the muscles attached to the superior curved line of the occipital bone and the 
space between this and the inferior curved line, becomes superficial by piercing 
the trapezius or the fascia between the occipital attachments of the trapezius and 
sterno-cleido-raastoid, and then runs forward in the scalp tissue to the vertex of 
the skull, anastomosing with the branches of the temporal and posterior auricular. 
Varieties.—The occipital is in rare cases a branch of the internal carotid; 
sometimes it is given off from the inferior thyroid. 
Surgical Anatomy (Fig. 446).—The vessel is deeply situated and seldom 
wounded; it may become necessary to ligate it for cirsoid aneurism. It can be 
ligated at its point of origin from the external carotid, or in the scalp tissue just 
above the superior curved line of the occipital bone. 
Branches.—The muscular, sterno-mastoid, auricular, meningeal, and arteria 
princeps cervicis. Muscular branches are given off to the muscles with which it 
is in contact; one large muscular branch, the sterno-mastoid, is given off to the 
sterno-cleido-mastoid, and is distributed to the muscle with the spinal acces- 
sory nerve. The auricular branch supplies the posterior portion of the external 398 
THE BLOOD-VASCULAR SYSTEM. 
ear. The meningeal branch becomes one of the posterior meningeal arteries, and 
enters the skull through the jugular foramen. The arteria princeps cervicis 
passes downward, and, deeply situated, divides into two sets of branches, one 
anastomosing with the deep cervical branch of the superior intercostal artery, the 
other with the superficial cervical branch of the transversalis colli. 
The Posterior Auricular Artery.— Origin : from the external carotid, its poste- 
rior surface above the origin of the occipital. Course and termination :it passes 
upward and backward beneath the parotid gland to the scalp tissue behind the 
ear and in front of the mastoid process, where it divides into two branches : the 
mastoid, supplying the scalp tissue over the mastoid process, and anastomosing 
with the occipital; and an auricular supplying the back of the ear, and anasto- 
mosing with branches of the temporal. 
Variations.—The posterior auricular artery is sometimes a branch of the occi- 
pital. On the other hand, it is sometimes a vessel much larger than the occi- 
pital, being distributed to the region usually supplied by the occipital and 
temporal arteries. 
Surgical Anatomy.—The position of the posterior auricular should be remem- 
bered in the frequent operations on the mastoid; it is, however, a small vessel 
and usually easily dealt with surgically. 
Branches.—ln addition to the two terminal branches, the auricular and mastoid 
already sufficiently described, the artery gives off a stylo-mastoid branch, which 
enters the stylo-mastoid foramen, and supplies branches to the mastoid cells, 
tympanum, and internal ear. 
The Ascending Pharyngeal Artery,— Origin : from the internal and posterior 
surface of the external carotid, within half an inch of its origin from the com- 
mon carotid. Course and termination :it runs upward on the side of the pharynx 
and, covered by the internal carotid artery, to the base of the skull. 
Variations,—The ascending pharyngeal is sometimes a branch of the internal 
carotid or common carotid. 
Surgical Anatomy.—ln part of its course the artery is situated between the 
tonsil and the internal carotid, and might be injured in operations about the 
tonsil. 
Branches.—The branches of the ascending pharyngeal are the prevertebral, 
the pharyngeal, and the meningeal. The prevertebral branches supply the ante- 
rior recti and the longus colli muscles, and the nerves and lymphatic nodes of this 
region. The pharyngeal branches supply the pharynx, tonsil, and soft palate. 
The meningeal are several small vessels entering the skull through the jugular 
foramen, the anterior condylar foramen, and the foramen lacerum medium. 
The Temporal Artery.— Origin :it is one of the terminal branches of the exter- 
nal carotid, and begins at a point a little below the condyle of the jaw. Course 
and, termination : it passes upward through the substance of the parotid gland 
external to the zygoma, to a point from an inch and a half to two inches above 
the zygoma, and here divides into the anterior and posterior temporal arteries. 
Variations.—The temporal artery is not frequently subject to variations from 
the usual type. It may be very small, and its place be taken by a large poste- 
rior auricular. The transverse facial may be of large size and take the place of 
a small facial artery. 
Surgical Anatomy.—From its superficial position the temporal and its terminal 
branches are often injured in scalp wounds ; ligation of the main trunk may be 
required for cirsoid aneurism. The operation can be done by an incision two 
inches in length, a finger’s breadth in front of the ear, the centre of the inci- 
sion being an inch above the zygoma. The artery here is accompanied by the 
auriculo-temporal nerve, which should be avoided. 
Branches.—The branches of the temporal are its terminal branches, the ante- 
rior temporal and the posterior temporal, and the transverse facial, middle tempo- 
ral, and anterior auricular. The transverse facial (Fig. 448) is given off close to 
the point of origin of the temporal, passes transversely forward across the face THE ARTERIES. 
399 
beneath the zygoma, on the surface of the masse ter, and anastomoses with branches 
of tire facial. The middle temporal branch perforates the temporal fascia, and sup- 
plies the temporal muscle, anastomosing with the deep temporal branches of the 
internal maxillary. The anterior auricular branch is distributed to the anterior sur- 
face of the external ear. The anterior temporal winds forward and upward over the 
frontal bone, and supplies the scalp structures. In this position the artery is very 
superficially situated ; its pulsations can be readily felt, and often seen. The 
position of the artery is such that, in giving an anaesthetic the ansesthetizer can 
from this vessel feel the condition of the pulse. The anterior temporal is the 
artery usually selected to perform the operation of arteriotomy. The posterior 
temporal passes backward and upward superficially in the scalp to the vertex of 
the skull, supplying the scalp over the sides of the vertex, and anastomosing with 
the occipital, the posterior auricular, and the vessel of the opposite side. 
The Internal Maxillary Artery (Figs. 449, 450) is one of the terminal divisions 
of the external carotid. Origin: from the external carotid a little below the 
condyle of the jaw. Course and termination: the artery is at first in the substance 
of the parotid gland, whence it passes inward and forward to the spheno-maxil- 
Fig. 449.—Internal maxillary artery. (Testut.) 
lary fossa. It is divided into three portions, a maxillary, a pterygoid, and a 
spheno-maxillary. The maxillary portion lies below the inferior border of the 
external pterygoid muscle; the pterygoid portion lies on the anterior surface of 
the pterygoid muscle ; the spheno-maxillary portion rests on the superior maxillary 
bone, and in the spheno-maxillary fossa. 400 
THE BLOOD-VASCULAB SYSTEM. 
Variations.—The internal maxillary in rare cases is given off as a branch from 
the facial; the number of branches varies considerably, because very often two or 
more arise by a common trunk from the artery. 
Surgical Anatomy.—The main trunk of the vessel is deeply situated, but may 
be injured in penetrating wounds of the face. Ligation of the vessel would be 
difficult, and that of the external carotid would be preferable. Two of the 
branches of the internal maxillary are of special surgical interest, the middle 
meningeal artery and the infraorbital artery. The middle meningeal is often 
injured in cases of fracture of the skull; the artery is situated between the bone 
and dura, and pressure-symptoms from rupture of this vessel are often character- 
istic, coming on slowly after an injury. The vessel can be exposed by making an 
Middle Meningeal 
Ptevygo-Palaline 
Spheno-Palatine 
Vidian 
Infraorbital 
Sin ail Meningeal 
Descending 
Palatine 
Buccal 
'Pterygoid 
Masseteric 
Fig. 450.—Diagram of the internal maxillary artery and its branches. 
opening in the skull, the centre of which should be a point an inch and a half 
behind the external angular process of the frontal bone. In the Hartley operation 
for removal of the Gasserian ganglion the position of this vessel should be care- 
fully studied. The infraorbital artery is sometimes injured in removing the 
second division of the fifth pair of nerves back as far as Meckel’s ganglion ; the 
blood in such a case might pass into the antrum of Highmore and from this into 
the nasal cavities. Such hemorrhage could be controlled by plugging the anterior 
and posterior nares. 
Branches.—From the first or maxillary portion of the vessel are given off 
the tympanic, the middle meningeal, the small meningeal, and the inferior dental 
arteries. The tympanic passes through the Glaserian fissure to the tympanum, 
which it aids in supplying; it gives off branches also to the membrana tympani. 
The middle meningeal enters the skull through the foramen spinosum, occupies a 
groove in the bone of the middle fossa at the base of the skull, winds upward 
and outward, and divides into an anterior and posterior branch. These branches 
groove the inner surface of the bone, running between the bone and the dura, 
and furnish the principal arterial supply of the latter. The small meningeal 
artery passes through the foramen ovale into the cranial cavity, and supplies the 
Gasserian ganglion and contiguous dura. The inferior dental is a large branch 
which passes downward to the inferior dental foramen, which it enters with the 
inferior dental nerve, running forward in the inferior dental canal to supply the 
inferior maxilla and teeth. Before entering the inferior dental foramen the 
artery gives off the mylohyoid branch, which is distributed to the mylohyoid 
muscle, and occupies the mylohyoid groove on the internal surface of the mandi- 
ble. The artery gives off branches to each tooth, and opposite the mental fora- 
men a mental branch, which passes forward to supply the structures of the chin. THE ARTERIES. 
401 
The branches of the 'pterygoid portion of the internal maxillary artery supply 
the muscles of mastication. They are the temporal, the masseteric, the pterygoid, 
and the buccal, and carry blood to the temporal, the masseter, the internal and 
external pterygoids, and the buccinator. 
The branches from the third or spheno-maxillary portion are the alveolar, the 
infraorbital, the descending palatine, the Vidian, the ptery go-palatine, and the 
spheno-palatine. The alveolar supplies the posterior portion of the alveolar process 
of the upper jaw, and also the molar and bicuspid teeth. The infraorbital passes 
with the infraorbital nerve along the infraorbital groove and canal, makes its 
appearance on the face at the infraorbital foramen, and supplies here the soft tis- 
sues over the superior maxillary bone, anastomosing with branches from the facial. 
In the orbit the artery gives off muscular branches, which supply the inferior 
oblique and inferior rectus muscles, and in the canal branches to the canine and 
incisor teeth. The descending palatine passes with the descending branches of 
Meckel’s ganglion down the posterior palatine canal to the mouth cavity, then 
runs in a groove on the under surface ot the hard palate forward to the anterior 
palatine canal, where it anastomoses with the anterior palatine artery, and sup- 
plies the gums and mucous membrane of the hard palate. The Vidian passes 
backward through the Vidian canal to be distributed to the pharynx and Eusta- 
chian tube. Tlie ptery go-palatine passes backward through the pterygo-pala- 
tine canal, and is also distributed to the upper part of the pharynx. The 
spheno-palatine passes through the spheno-palatine foramen into the nasal cavity. 
It divides into two branches, the naso-palatine, which runs in a groove ot the 
vomer downward and forward to the anterior palatine foramen, where it anasto- 
moses with the descending palatine artery; and an external branch, which sup- 
plies the mucous membrane of the outer wall of the nasal cavity. 
The Internal Carotid Artery (Fig. 443). 
Origin: from the common carotid opposite the superior border of the thyroid 
cartilage. Course and termination : the vessel runs upward in front of the trans- 
verse processes of the upper three or four cervical vertebrae to the carotid canal in 
the petrous portion of the temporal bones, runs through the canal to its internal 
opening, and enters the cranial cavity, and then enters the cavernous sinus, occu- 
pying a position between the fibrous covering of the sinus and its lining mem- 
brane. It leaves the sinus at the internal surface of the anterior clinoid process, 
and passes to the fissure of Sylvius, where it breaks up into its terminal branches. 
The artery is distributed mainly to the brain and eye. The vessel is divided into 
four portions, a cervical, a petrous, a cavernous, and a cerebral, which should be 
studied in detail. 
The cervical portion is that extending from its origin to the lower opening of 
the carotid canal. 
Relations. 
In front. 
Skin, superficial fascia. 
Platysma and deep fascia. 
Sterno-mastoid, stylo-glossus, and stylo-pharyngeus muscles. 
External carotid and occipital arteries. 
Hypoglossal nerve and glossopharyngeal nerve. 
Parotid gland. 
Externally. 
Internally. 
Internal jugular vein. 
Pneumogastric nerve. 
Pharynx. 
Inferior laryngeal nerve. 
Ascending pharyngeal ar- 
Internal 
carotid 
in the neck. 
tery. 
Tonsil. 402 
THE BLOOD-VASCULAB SYSTEM. 
Variations.—The internal carotid sometimes arises directly from the arch of 
the aorta. It is sometimes absent. It sometimes gives off branches in the neck, 
which are usually the occipital or ascending pharyngeal. 
Surgical Anatomy.—The vessel can be exposed for ligation by an incision 
along the internal border of the sterno-mastoid. The skin and superficial fascia 
should be divided, then the platysma and deep fascia; the sterno-mastoid should 
be drawn to the outer side, and the external carotid to the inner side ; care should 
be taken in passing the needle to avoid the pneumogastric nerve and the internal 
jugular vein, which accompany the artery. 
Branches.—As a rule, the internal carotid gives off no branches of importance 
in the neck. (See Variations.) 
The petrous portion of the vessel is that part contained in the carotid canal. 
Here the artery makes two sharp turns, which are supposed to diminish the 
arterial pressure. From this portion of the artery a small branch is given off 
to the tympanum. 
The cavernous portion is that part of the vessel which is in the cavernous sinus. 
Here the vessel gives off the following branches : the arterise receptaculi, the 
anterior meningeal, and the ophthalmic. The arterice receptaculi are small ves- 
sels which supply the pituitary body and the Gasserian ganglion. The anterior 
meningeal artery is distributed to the dura of the anterior fossa at the base of the 
skull. 
The Ophthalmic Artery (Fig. 451) passes with the optic nerve through the 
optic foramen into the orbit. It passes first forward and outward, then crosses 
the optic nerve and passes forward and inward, runs along the inner wall of the 
orbit, beneath the inner portion of the orbital margin, leaves the orbit, and termi- 
nates by dividing into the frontal and nasal arteries. In its course the ophthal- 
mic artery gives off branches to the walls and contents of the orbit. These 
branches are the central artery of the retina, the ciliary arteries, the lachrymal, 
the muscular, the supraorbital, the ethmoidal, the palpebral, and the terminal 
branches, the nasal and frontal arteries. The central artery of the retina is given 
off from the ophthalmic near the optic foramen. It accompanies the optic nerve, 
and is distributed to the retina. The vessel can be well seen in ophthalmoscopic 
examinations of the retina. The ciliary arteries are divided into three sets—the 
long, short, and anterior ciliary arteries. The short ciliary arteries are eight or 
ten in number, which pierce the sclerotic coat near the optic nerve, and run 
forward to supply the choroid. The long ciliary arteries, two in number, one on 
each side, pierce the sclera some distance from the optic nerve, and run forward 
to supply the ciliary body and iris. The anterior ciliary arteries are branches of 
the muscular branches of the ophthalmic. They pierce the sclera near the cornea 
and supply the ciliary body and the iris. The anterior and long ciliary arteries 
form an anastomosis around the outer margin of the iris, and also around the free 
margin of the iris. The lachrymal artery arises from the ophthalmic external 
to the optic nerve, passes forward and outward to the lachrymal gland, which it 
supplies, and, leaving the gland, sends small branches to the eyelids, known as 
external palpebral branches. Muscular branches are given off from various por- 
tions of the ophthalmic in its course to supply the muscles of the globe. The 
supraorbital artery is a vessel of some size, which runs along the roof of the orbit 
to the supraorbital notch. Leaving the orbit at this point, it courses upward in the 
muscles and integument of the forehead. The ethmoidal arteries, two in number, 
are given off from the ophthalmic opposite the anterior and posterior ethmoidal 
foramina. Entering the cranial cavity through these foramina they give off ante- 
rior meningeal vessels, supplying the dura in the anterior fossa at the base of the 
skull. The anterior ethmoidal is the larger, and, after giving off a meningeal 
branch, leaves the cranial cavity with the nasal nerve, passes through an opening 
in the cribriform plate to the nasal cavity, runs along the inner surface of the 
nasal bone, and supplies the tip of the nose. The palpebral arteries, two in 
number, the superior and inferior, supply the upper and lower lids. The nasal THE ARTERIES. 
403 
artery leaves the orbit above the inner canthus, and supplies the bridge of the 
nose, anastomosing with the angular branch of the facial. The frontal leaves the 
orbit at the upper and inner angle, winds up over the forehead near the median 
line, supplying the soft tissues in this position. 
Variations.—The ophthalmic is sometimes situated beneath the optic nerve, 
and on the inner side of the orbit throughout its entire course. The ophthalmic 
is sometimes a branch of the middle meningeal, or sometimes gives origin to the 
middle meningeal. Variations in the number and position of the branches as 
described frequently occur. 
Surgical Anatomy.—ln enucleation of the eye the larger branches of the oph- 
thalmic are, as a rule, not divided, and the resulting hemorrhage is slight and 
readily controlled. 
Aneurism of the ophthalmic occurs, producing exophthalmos and inter- 
ference with the function of the eye. To control such a condition ligation of the 
common carotid or internal carotid might be necessary. 
The cerebral portion of the internal carotid has for its branches the posterior 
communicating, the anterior choroid, the anterior cerebral, and the middle cerebral 
arteries. The posterior communicating passes backward to join the posterior 
cerebral artery, a branch from the basilar, and forms the lateral portion of the 
circle of Willis. The anterior choroid passes outward and backward to reach the 
descending horn of the lateral ventricle, where it supplies the*choroid plexus. 
The anterior cerebral runs forward and inward to reach the great longitudinal 
fissure between the hemispheres. In this fissure the artery lies close to its oppo- 
site mate, and connecting them is a short trunk, the anterior communicating. The 
vessel winds over the anterior extremity of the corpus callosum to reach its supe- 
rior surface. It gives off branches to the anterior perforated space, to the under 
surface of the frontal lobe, and the mesial surface of the hemisphere, and anasto- 
moses with the posterior cerebral artery. The middle cerebral artery passes 
forward and outward to the fissure of Sylvius, and then runs along the fissure of 
Sylvius to the insula and the external surface of the hemisphere. In its course 
it gives branches, which enter the anterior perforated space, and supply the 
Fig. 451.—Arteries of the orbit. (Testut.) 404 
THE BLOOD-VASCULAB SYSTEM. 
ganglia and other structures in the floor of the lateral ventricle. One of these 
vessels is of special interest, the lenticulo-striate artery, called also Charcot’s 
artery of cerebral hemorrhage, because it is a very common site of arterial rup- 
ture in cases of apoplexy. This vessel is situated between the external capsule 
and the corpus striatum. The cortical brain substance of the motor area is also 
supplied by the middle meningeal (Sylvian) artery, and here arterial lesions are 
common and often produce localizing symptoms. After discussing the vertebral 
artery, which with the internal carotid supplies the encephalon, the arterial sup- 
ply of the brain will be given more in detail. 
ARTERIES OF THE UPPER EXTREMITIES. 
THE SUBCLAVIAN ARTERY. 
The subclavian artery (Fig. 452) takes its origin on the left side from the arch 
of the aorta, on the right side from the brachio-cephalic artery. Each vessel 
passes upward and outward into the neck, and then arches downward and out- 
ward to terminate at the lower border of the first rib in the axillary. Each ves- 
Fig. 452.—Subclavian and axillary arteries. (Testut.) 
sel is divided into three portions, according to its situation with reference to the 
scalenus anterior muscle. The first portions of the subclavian arteries differ, and 
must be described separately. A single description will answer for the second 
and third portions of both arteries. 
The first portion of the left subclavian arises from the arch of the aorta, and 
extends to the inner border of the scalenus anterior muscle. The vessel is deeply 
situated and in the lower part of its course somewhat resembles the brachio- 
cephalic artery. THE ARTERIES. 
405 
Relations. 
In front. 
Pleura and lung. 
Pneumogastric and phrenic nerves. 
Left carotid artery. 
Left internal jugular and brachio-ccphalic veins. 
Sterno-hyoid, sterno-thyroid, and sterno-mastoid muscles. 
Inner side. 
Trachea. 
(Esophagus. 
Thoracic duct. 
First portion 
of loft 
subclavian. 
Outer side. 
Pleura. 
(Esophagus. 
Thoracic duct. 
Behind. 
The first portion of the right subclavian takes its origin from the brachio- 
cephalic artery, and extends upward and outward to the inner border of the 
scalenus anterior. 
Relations. 
Skin, superficial fascia. 
Platysma, deep fascia. 
Sterno-mastoid, sterno-hyoid, sterno-thyroid muscles. 
Internal jugular vein. 
Pneumogastric and phrenic nerves. 
In front. 
Beneath. 
First portion 
Pleura. 
subclavian. 
of right 
Behind. 
Recurrent laryngeal nerve. 
The second portion of the subclavian is behind the scalenus anterior muscle. 
Relations. 
In front. 
Skin, superficial fascia. 
Platysma, deep fascia. 
Sterno-mastoid and scalenus anterior muscles. 
Phrenic nerve. 
Subclavian vein 
Above. 
Second portion 
Below. 
Brachial plexus. 
of subclavian 
artery. 
Pleura. 
Scalenus raedius muscle. 
Behind. 
Pleura. 
The third portion of the subclavian extends from the outer border of the scale- 
nus anterior to the lower border of the first rib. 406 
THE BLOOD-VASCULAR SYSTEM. 
Relations. 
In front. 
Skin, superficial fascia. 
Platysma, deep fascia. 
Suprascapular artery. 
External jugular vein. 
Clavicle. 
Above. 
Brachial plexus. 
Omo-hyoid muscle. 
Below. 
First rib. 
Third portion 
of 
subclavian. 
Behind. 
Scalenus medius. 
Variations.—The subclavian is sometimes on both sides a direct trunk from the 
aortic arch, or on both sides a branch from a right and left brachio-cephalic artery. 
The vessel is usually at its high point in the neck a half inch above the clavicle, 
but sometimes it rises considerably higher ; sometimes it is beneath the clavicle 
entirely. The branches of the subclavian often present variations which are of 
importance and which will be discussed in studying the individual branches. 
Surgical Anatomy (Figs. 442, 446).—The surgical anatomy of the first and 
second portions of the subclavian is not of great importance, because, owing to 
the great depth of the vessel and its relations to important structures, it is seldom 
interfered with surgically. The vessel, however, can be and has been ligated in 
the first two portions of its course. The surgical anatomy of the third portion is 
of great importance, and should be carefully studied. The blood supply of the 
upper extremity can be controlled by compressing the subclavian digitally against 
the upper surface of the first rib. This method is now, however, seldom 
employed. Ligation of the third portion of the subclavian may be required for 
injuries of the arteries of the upper extremity below this point, or for aneurism. 
It is also a preliminary step in the amputation of the entire upper extremity. 
The operation is made in the following way: An incision four inches in length is 
made over the clavicle beginning a little external to the sterno-clavicular articu- 
lation. This incision divides the skin, superficial fascia, platysma, and deep 
fascia. In making this superficial incision the external jugular is exposed, and 
may be drawn to the inner side or divided between two ligatures. The sub- 
clavian triangle is now outlined, bounded below by the clavicle, above by the pos- 
terior belly of the omo-hyoid, and internally by the sterno-cleido-mastoid. The 
suprascapular artery crosses this triangle above and parallel with the clavicle. 
Carefully dividing the areolar tissue at the floor of this triangle, a second triangle 
is exposed; this second triangle is bounded above by the brachial plexus, below 
by the first rib, and internally by the scalenus anterior muscle. The third portion 
of the subclavian artery is in this small triangle. In ligating the vessel care 
should be taken to avoid the subclavian vein, which is below, the brachial plexus, 
which is above, and the phrenic nerve, which lies on the anterior surface of the 
scalenus anterior. Collateral circulation is usually readily established between the 
branches of the first portion of the subclavian, and the branches from the axil- 
lary, external carotid, intercostals, and deep epigastric. 
Branches.—The branches of the subclavian are, as a rule, four in number, and 
given off from the first portion of the vessel, although sometimes the superior 
intercostal is given off from the second portion, and the posterior scapula is often 
a branch from the third portion. They are the vertebral, the internal mammary, 
the thyroid axis, and the superior intercostal. 
The Vertebral (Fig. 443) is given off from the posterior surface of the sub- THE ARTERIES. 
407 
clavian ; it passes upward to reach the vertebral opening in the costo-transverse 
process of the sixth cervical vertebra, and continues upward through the vertebral 
foramina of the cervical vertebrae above; reaching the atlas it winds over the 
upper surface of the posterior arch in a groove or foramen behind the superior 
articular process, and passes into the cranial cavity through the foramen magnum ; 
the two vertebral arteries within the skull unite to form the basilar, which then 
breaks up into branches, which assist the internal carotid in supplying the ence- 
phalon. Variations.—The vertebral is sometimes a branch of the aortic arch; 
sometimes a branch of the common carotid. Although as a rule it enters the 
vertebral foramen of the sixth cervical, it in some cases enters none below that 
of the fifth, or even the third. 
Surgical Anatomy (Fig. 453).—The ligation of the vertebral is a deep opera- 
tion, but can be readily done if the anatomical position of the vessel and the 
landmarks leading to it are understood. An incision is made along the inner 
border of the sterno-mastoid, beginning just above the sterno-clavicular articula- 
tion and extending upward for four or five inches. The skin, superficial fascia, 
platysma and deep fascia are divided; the carotid is drawn to the outer side, the 
DEEP FASCIA 
MASSETER 
facial artery 
TRANSVERSE PROCESS** 
PLATYSMA 
SIXTH CERVICAL- 
VERTEBRA 
VERTEBRAL ARTERY 
RECURRENT NERVE 
INTERNAL JUGULAR VEIN- 
DESCENDENS HYPO-- 
QLOSSI NERVE 
INFERIOR THYROID 
ARTERY 
COMMON CAROTID-. 
ARTERY 
LONGUS COLL!-- 
VERTEBRAL ARTERY 
THYROID GLAND 
STERNO- 
HYOIDEUS 
Fig. 453.—Surgical relations of the facial, vertebral, and inferior thyroid arteries. (Kocher.) 
transverse process of the sixth cervical is sought, and below this point and 
between the scalenus anterior and the longus colli muscles the vertebral artery is 
found. The vessel may be approached by an incision of sufficient length made 
along the outer border of the sterno-cleido-mastoid, instead of along its inner 
border. In this case the muscle and deep vessels are drawn to the inner side. 
Branches.—The branches of the vertebral are divided into two sets ; those in 
the neck, and those in the cranium. The branches in the neck are the lateral spi- 
nal and the muscular. The spinal branches enter the spinal canal through the 
intervertebral foramina, and supply the membranes of the cord and the vertebrae. 
Muscular branches are distributed to the deep muscles of the neck. The branches 
in the cranium are the posterior meningeal, the posterior inferior cerebellar, and 
the spinal. The posterior meningeal branches are small vessels supplying the 
dura of the posterior fossa. The spinal arteries are divided into two sets, the 
anterior and posterior spinal. The anterior spinal branch unites with its fellow 
of the opposite side and forms the single anterior spinal artery. The posterior 408 
THE BLOOD- VASCULA It SYSTEM. 
spinal descends along the cord in front of the posterior roots of the spinal nerves, 
and communicates with the lateral spinal. The posterior inferior cerebellar artery 
supplies the posterior and inferior surfaces of the cerebellum, and gives off small 
branches to the medulla and the choroid plexus of the fourth ventricle. 
The Basilar Artery (Figs. 454, 455) is formed by the union of the vertebral 
arteries; it runs forward and upward in the groove on the under surface of the 
pons, and divides into the posterior cerebral arteries. In its course it gives off as 
branches the transverse, the anterior inferior cerebellar and superior cerebellar 
arteries. The transverse arteries supply the pons, and one branch enters the 
internal auditory meatus with the facial and auditory nerve. The anterior infe- 
rior cerebellar arteries supply the anterior portion of the inferior surface of the 
cerebellum. The superior cerebellar arteries wind backward and upward to the 
upper surface of the cerebellum, which they supply. 
Fig. 454.—Arteries at the base of the brain, seen in their relations to the skull. (Testut.) 
The terminal branches of the basilar, the posterior cerebral arteries, are ves- 
sels of large size, which anastomose with the posterior communicating to com- 
plete the circle of Willis behind. They pass to the under surface of the occipital 
lobe, which they supply; giving off also a choroid branch. 
With this knowledge of the distribution of the internal carotid and vertebral 
arteries, we can study the free anastomosis of the arteries at the base of the brain, 
known as the circle of Willis. 
The Circle of Willis is formed in front by the anterior cerebral arteries and the 
anterior communicating which unites them; behind by the division of the basilar 
into the posterior cerebral; and laterally by the internal carotid and posterior 
communicating. From the cerebral arteries close to, within an inch of, the circle 
of Willis deep ganglionic branches are given off which penetrate the brain sub- 
stance, and are distributed to the great ganglia at the base of the brain and the 
contiguous brain structures. Beyond this the vessels supply the cortical portions THE ARTERIES. 
409 
of the encephalon. A point of practical importance in this connection is the fact 
that the arteries which supply the brain are terminal arteries, and that there is no 
anastomosis between the vessels supplying the ganglia and central structures of 
Anterior Communicating 
the brain and the vessels supplying 
the cortex. As a result, whenever an 
injury or lesion to an artery of the 
brain occurs, the portion of the brain 
tissue supplied by the vessel beyond 
the point of the lesion has its arterial 
supply permanently cut otf, and ne- 
crosis and softening follow. 
/ Anterior Cerebral 
- Middle Cerebral 
Internal Carotid 
"'Posterior Cerebral 
■ Posterior Communicating 
Anterior Inferior Cerebellar 
Superior Cerebellar 
'Basilar 
Posterior Inferior Cerebellar 
I Vertebral 
Anterior Spinal 
Posterior Spinal 
Fig. 455—Key to Fig. 454. 
The Internal Mammary Artery 
(Fig. 456). 
This vessel is given off from the ante- 
rior surface ol the first portion of the sub- 
clavian. It passes downward to the inner 
surface of the cartilage of the first rib, runs 
downward between the costal cartilages 
and the pleura, about half an inch external 
to the border of the sternum, to the sixth 
intercostal space, and there divides into 
the superior epigastric and musculo-phrenic 
arteries. In its course it gives oft the su- 
perior phrenic, the mediastinal, the ante- 
rior intercostal, and the anterior perforat- 
ing. The superior phrenic accompanies the 
phrenic nerve in its distribution. The 
mediastinal branches are distributed to the 
structures of the anterior mediastinum. 
The anterior intercostals are given oft at 
each of the upper five or intercostal 
spaces and supply the anterior portion 
of those spaces, anastomosing with the 
aortic intercostal arteries. The perforating 
branches pierce the intercostal muscle in 
each space, and pass forward and outward 
to supply the pectoral muscle, the mam- 
mary gland, and the integument over the 
Fig. 456.—Internal mammary and deep epigas- 
tric arteries. (Testut.) 
pectoral region. The terminal branches are the musculo-phrenic and superior 
epigastric. The musculo-phrenic winds outward and downward along the inner 410 
THE BLOOD- VASCULAR SYSTEM. 
surface of the costal arch, and opposite each one of the lower intercostal spaces. 
It gives off an intercostal branch, and sends also a number of muscular branches 
to the diaphragm. The superior epigastric, the other terminal branch, descends 
into the abdominal wall, at first occupying a position between the rectus muscle 
and its posterior sheath, then passing into the substance of the rectus, and anasto- 
moses with the deep epigastric artery. 
Surgical Anatomy (Fig. 442).—The surgical anatomy of the internal mam- 
mary includes the discussion of aneurism and injuries. The vessel can be ligated 
in any of the six upper intercostal spaces one-half inch external to the sternum. 
The best plan of operation is a transverse incision over a costal cartilage, exposure 
of the cartilage for an inch, removal of a section of the cartilage, and ligation 
of the vessel beneath. 
The Thyroid Axis. 
The thyroid axis (Fig. 443, TFIY.) is a large trunk which arises from the 
anterior and superior surface of the first part of the subclavian, and divides into 
three branches, the inferior thyroid, the transversalis colli, and suprascapular. 
The Inferior Thyroid Artery passes upward and inward in front of the ver- 
tebral and behind the common carotid artery, internal jugular vein, and pneu- 
mogastric nerve to the inferior portion of the lateral lobe of the thyroid body, to 
which it is distributed. The recurrent laryngeal nerve passes sometimes in front 
and sometimes behind the artery; it is in intimate relation to the vessel, and in 
ligating the artery this relationship must be borne in mind. 
Varieties.—The inferior thyroid is sometimes a branch of the vertebral or 
the common carotid, or instead of arising from the thyroid axis may be a branch 
from the subclavian. 
Surgical Anatomy (Fig. 453).—The inferior thyroid is sometimes ligated in 
lesions of the thyroid gland for the purpose of diminishing the blood supply. It 
must be ligated during the operation of extirpation of a thyroid lobe. Ligation 
of the inferior thyroid can be made by exposing the vessel by an incision along 
the inner border of the sterno-mastoid, beginning at the sterno-clavicular articu- 
lation and passing upward for four inches. After dividing the superficial struct- 
ures the carotid artery is drawn outward and the vessel is found external to the 
trachea; the recurrent laryngeal nerve is in close contact with the vessel, and in 
the groove between the oesophagus and trachea, usually in front of the vessel, 
and must be carefully avoided. 
Branches of the inferior thyroid are the muscular, ascending cervical, inferior 
laryngeal, tracheal and oesophageal. Muscular branches are given off to the mus- 
cles with which it is in contact. The ascending cervical branch passes upward 
and outward over the scalenus anterior muscle, and anastomoses with branches 
from the occipital and ascending pharyngeal. The inferior laryngeal accom- 
panies the recurrent laryngeal nerve in its distribution to the larynx. The 
tracheal branches are distributed to the trachea, and the oesophageal to the 
oesophagus. 
The Suprascapular Artery passes outward and backward to the upper border of 
the scapula. The vessel at first runs almost parallel with the clavicle. Reach- 
ing the upper border of the scapula, it winds into the supraspinous fossa, supply- 
ing the supraspinatus muscle, then passes into the infraspinous fossa supplying the 
infraspinatus muscle ; its branches anastomose with branches from the posterior 
scapular and the dorsal scapular arteries. 
Varieties.—This vessel is sometimes a separate branch from the subclavian, 
sometimes a branch from the axillary. 
Surgical Anatomy.—The vessel can be ligated by the same incision already 
described for the ligation of the third portion of the subclavian. 
Branches, in addition to the terminal branches already given, are, muscular to 
contiguous muscles, suprasternal to the integument over the sterno-clavicular THE ARTERIES. 
articulation, nutrient to the clavicle, supra-acromial to the tissues over the acro- 
mion, and subscapular to the subscapularis muscle. 
The Transversalis Colli Artery passes outward and backward in front of the 
scaleni muscles aud the brachial plexus to the trapezius muscle; here it divides 
into two branches, the superficial cervical and the posterior scapular. The 
superficial cervical passes behind the trapezius muscle upward, and supplies the 
trapezius, levator scapulae, and splenius. The posterior scapular passes down- 
ward along the vertebral border of scapula to its inferior angle. In its course it 
is covered by the rhomboid muscles, and anastomoses with the scapular arteries— 
suprascapular, dorsal scapular, and subscapular. 
Varieties.—The posterior scapular is very often a separate branch of the third 
portion of the subclavian. 
Surgical Anatomy.—The presence of the posterior scapular as a branch from 
the third portion of the subclavian is to be borne in mind in ligating that vessel : 
and in amputation of the entire upper extremity, the operator should know that, 
after ligation of the subclavian, all bleeding of consequence is controlled, except 
that from the posterior scapular, when it is a branch from the third portion of the 
subclavian, which may give rise to considerable hemorrhage, when the scapula is 
removed, and requires ligation. 
This vessel arises from the posterior surface of the subclavian, either from its 
first or second portion. The artery passes backward and is divided into two 
branches. One, the deep cervical, passes upward, deeply situated behind the 
transverse processes, and anastomoses with the princeps cervicis branch of the 
occipital. The other branch passes downward in front of the neck of the first 
rib to the first intercostal space, which it supplies, aud gives off also a branch 
to the second intercostal space. 
Variations.—The superior intercostal is sometimes a branch of the thyroid 
axis. The deep cervical is sometimes a branch from the subclavian, sometimes 
from the posterior scapular. 
The Superior Intercostal Artery. 
THE TRIANGLES OF THE NECK. 
The quadrilateral surface of the neck, which is bounded below by the clavicle, 
above by the inferior border of the lower jaw aud a line drawn from the angle of 
the jaw to the mastoid process, behind by the anterior border of the trapezius 
muscle and in front by the median line of the neck, is divided by the sterno- 
cleido-mastoid muscle into two triangles, called the anterior and posterior triangles 
of the neck. These two triangles are subdivided, the posterior into two, the 
occipital, and the subclavian, by the posterior belly of the omo-hyoid ; the ante- 
rior into three by the anterior belly of the omo-hyoid, and the two bellies of the 
digastric. These are called the inferior carotid, the superior carotid, and the sub- 
maxillary triangles. These triangles are important anatomical regions and must 
be carefullv studied. The student is advised to draw a sketch of these triangles, 
and, at this stage of his study, to add the aiteiies which aie found in them ; 
later as the subjects of the veins, lymphatics, and nerves have been mastered, 
these structures should be added to the sketch, and the topographical anatomy 
completed. . 
The occipital triangle has but one vessel ot large size, the _ transversalis colli. 
The subclavian triangle contains the subclavian and the origin of its branches. 
The inferior carotid triangle contains the common carotid, the inferior thyroid, 
and the vertebral. The superior carotid triangle contains the common carotid, 
the internal and external carotids, and the first portions of all the branches of 
the external carotid, except the terminal branches, the temporal and internal 
maxillary, and usually the posterior auricular. The suhmaxillary triangle contains 
the upper portion of the external carotid with its branches—the temporal, internal 412 
THE BLOOD-VASCULAR SYSTEM. 
maxillary, and posterior auricular—the internal carotid deeply situated, and the 
facial and lingual. 
THE AXILLARY ARTERY (Fig. 457). 
The axillary artery begins where the subclavian ends, at the lower border of 
the first rib, passes downward and outward through the axillary space to its lower 
margin—i. e., the outer edge of the latissimus, and there terminates by becoming 
the brachial. The artery is crossed by the pectoralis minor muscle, which divides 
it into three portions. The first portion is between the lower border of the first 
rib and the inner margin of the pectoralis minor; the second portion is behind 
the pectoralis minor; and the third portion is between the outer border of the 
pectoralis minor and the lower border of the axillary space. The relations of 
these three portions differ, and it is well to study them separately. 
Relations of the First Portion of the Axillary Artery. 
In front. 
Skin, superficial and deep fascise. 
Pectoralis major. 
Costo-coracoid membrane. 
Outer side. 
Brachial plexus of nerves. 
First portion 
of 
axillary artery. 
Inner side. 
Axillary vein. 
Behind. 
First intercostal space. 
Serratus magnus muscle. 
Relations of the Second Portion of the Axillary Artery. 
In front. 
Skin, superficial and deep fasciae. 
Pectoralis major. 
Pectoralis minor. 
Outer cord of brachial 
plexus. 
Outer side. 
Second portion 
of 
axillary artery. 
Axillary vein. 
Inner cord of brachial 
plexus. 
Inner side. 
Behind. 
Subscapularis muscle. 
Posterior cord of brachial plexus. 
Relations of the Third Portion of the Axillary Artery. 
Skin, superficial and deep fasciae. 
Pectoralis major. 
Inner head of median nerve. 
In front. 
Outer side. 
Inner side. 
Ooraco-brachialis muscle. 
Median and musculo-cuta- 
Third portion 
of 
Ulnar nerve. 
Internal cutaneous nerve. 
neous nerves. 
axillary artery. 
Behind. 
Axillary vein. 
Subscapularis muscle. 
Latissimus and teres major muscles. 
Musculo-spiral and circumflex nerves. THE ARTERIES. 
413 
Variations.—The axillary sometimes gives off one of the arteries of the fore- 
arm. This is usually the radial, but is sometimes the ulnar, and sometimes the 
interosseous. Very often the usual number of branches from the axillary is 
diminished by the origin of two or more from a common trunk. The third por- 
tion of the axillary is sometimes crossed by a muscular slip extending from the 
pectoralis major to the latissimus dorsi. 
Surgical Anatomy (Fig. 458).—The artery may be ligated in any portion of its 
course. The vessel is easily found and ligated in the third portion, and may be 
exposed and ligated by a deep dissection in the first portion. The second portion 
is so covered by the pectoralis minor that a division of this muscle would be 
necessary to expose the artery; and, therefore, this portion would not be selected 
VERTEBRAL 
Fig. 457.—Axillary and subclavian arteries. (Testut.) 
for ligation. Ligation of the first portion of the axillary can be done in the fol- 
lowing way : An incision four inches in length is made below the middle of the 
clavicle and parallel with the clavicular fibres of the pectoralis major muscle. 
This incision should divide the skin, superficial and deep fasciae, and expose the 
pectoralis major muscle. The muscle-fibres should not be cut across, but sepa- 
rated by blunt dissection, held apart by retractors, and the pectoralis minor mus- 
cle sought for and exposed. Between the clavicle and the inner border of the 
pectoralis minor stretches a strong fibrous layer, the costo-coracoid membrane, 
which being divided, the axillary artery will be exposed, with the axillary vein 
situated internally and beneath, and the brachial plexus above and externally. 
These structures are to be avoided in applying a ligature. The ligation of the 
third portion of the artery requires but a superficial dissection. If the axillary 
space is divided from before backward into thirds, the vessel will be found at the 
junction of the anterior with the middle third. An incision two and a half 
inches long is made at this point, and parallel to the course of the vessel. The 
skin and superficial and deep fasciae being cut through, fhe vessel will be exposed, 414 
THE BLOOD-VASCULAB SYSTEM. 
with the axillary vein internally and beneath, and the ulnar nerve to the inner 
side. The median nerve is externally and above, its inner head crossing in front 
of the artery. These structures are to be avoided in passing the aneurism-needle. 
The Branches of the axillary artery are usually seven in number, two, the 
triceps's 
INNER HEAD \ 
ANASTOMOTIC A' 
MAGNA ARTERY 
-MEDIAN NERVE 
ULNAR NERVE' 
ARTERY 
CUTANEOUS 
NERVE 
SUPERIOR PROFUNDA 
" ARTERY 
ULNAR NERVE- 
TRICEPS- 
AXILLARY ARTERY 
DISTAL END 
M USCU LO-SPI R A L - 
NERVE 
.MEDIAN NERVE 
CORACO-BRACHIALIS 
MUSCULO-CUTANEOUS 
rj:x NERVE 
BRANCH OF SU PE RI O R 
PRO FU N DA ARTERY 
TRICEPS^ 
LONG HEAD 
LATISSIMUS—’ 
BRACHIAL VEIN 
ULNAR NERVE. 
-SUBSCAPULAR 
ARTERY 
CIRCUMFLEX NERVE, 
-SUBSCAPULAR 
NERVE 
TRICEPS. 
LONG HEAD 
-SUBSCAPULAR 
ARTERY 
TERES MAJOR 
SSUBSCAPU- 
| LA RIS 
DORSALIS SCAPULAE 
ARTERY 
Fig. 458.—Surgical relations of the axillary, suhscapular, brachial, superior profunda, and anastomotica 
magna arteries. The right arm is represented as raised almost to the perpendicular. (Kocher.) 
superior thoracic and acromio-thoracic, from the first portion ; two, the long 
thoracic and alar thoracic from the second ; and three, the subscapular and the 
anterior and posterior circumflex, from the third portion. The superior thoracic 
arises from the first portion of the axillary, and passes downward and forward to THE ARTERIES. 
415 
supply the pectoralis major and minor muscles. The acromio-thoracic artery 
arises from the first portion of the axillary ; it breaks up into three sets of 
branches : one passes outward to the acromion, the second passes down the arm 
with the cephalic vein, and the third supplies the pectoral and the serratus magnus 
muscles. The long thoracic artery arises from the second portion of the axillary, 
passes downward along the outer border of the pectoralis minor, and sends 
branches to the serratus magnus, the pectorales major and minor, and the mam- 
mary gland. The alar thoracic, arising from the second portion, consists either 
of a single branch or a number of small branches, distributed to the lymphatic 
glands, the fat and the areolar tissue of the axilla. The subscapular artery is a 
large branch which arises from the third portion of the axillary. It passes down- 
ward on the subscapularis muscle, and, at about the centre of the axillary border of 
the scapula, it gives off a large branch, the dorsalis scapula artery, which winds into 
the infraspinatus muscle, and anastomoses with the suprascapular and posterior 
scapular arteries. The rest of the artery passes downward on the chest wall, 
and is distributed to the muscles in this region—the subscapularis, the serratus 
magnus, the latissimus, and the teres major. The posterior circumflex is larger 
than the anterior. It arises from the third portion of the axillary, and winds 
backward between the teres muscles, and between the humerus and long head of 
the triceps. It accompanies the circumflex nerve, and supplies the deltoid and 
other structures about the shoulder-joint. The anterior circumflex arises from 
the third portion of the axillary artery. It passes forward in front of the 
humerus, is covered by the coraco-brachialis and the tendon of the biceps, sends 
branches to the shoulder-joint, and anastomoses with the posterior circumflex 
artery. 
THE AXILLARY SPACE. 
At this stage the student is advised to draw the axillary space, its boundaries, 
and the arteries contained in it. Later, as the subjects of the veins, lymphatics, 
and nerves are mastered, these should be added to the sketch. 
The Axillary Space is one of much practical importance, for it is often 
invaded by the surgeon in operative work, such as clearing the axilla in con- 
nection with the removal of carcinoma of the mammary gland. This operation 
practically amounts to a dissecting of the axilla and demands a thorough knowl- 
edge of the anatomy of the part. 
The axilla or arm-pit is the wedge-shaped space between the inner surface 
of the arm and the side of the chest. It presents for examination as boundaries 
anterior, posterior, internal, and external walls, a base and an apex. The anterior 
trail is formed by the pectoral muscles ; the posterior wall by the latissimus, the 
teres major, and the subscapularis muscles ; the inner tv all by the upper four ribs 
and intercostal spaces, covered by the serratus magnus muscle; and the outer 
wall by the humerus, covered by the coraco-brachialis muscle and the biceps 
tendons. The apex corresponds to the small area above the first rib from which 
the brachial plexus, and the axillary artery and vein emerge. The base is formed 
by the integument and fascia which stretch across the arm-pit from the pectoralis 
major to the latissimus dorsi. The arterial contents are the axillary artery and 
its branches. In addition the space contains the accompanying* veins, the 
brachial plexus of nerves, the axillary lymphatic nodes and vessels, and con- 
siderable fat and areolar tissue. The position of these structures in the space and 
their relations to each other should be carefully studied. 
THE BRACHIAL ARTERY (Fig. 459). 
The brachial artery, the continuation of the axillary, begins at the outer border 
of the axillary space. It passes down the inner aspect of the arm, covered by the 
dec]) fascia, and lying on the inner border of the coraco-brachialis and biceps mus- 
cles ; it terminates in the forearm about half an inch below the bend of the elbow 416 
THE BLOOD-VASCULAR SYSTEM 
by dividing into the ulnar and radial. The artery is usually accompanied by 
vena 3 coraites. 
Relations of the Beachial. 
In front. 
Skin, superficial fascia. 
Deep fascia. 
Median nerve. 
Basilic vein. 
Outer side. Inner side. 
Coraco-brachialis 
and biceps mus- 
cles. 
Brachial 
artery. 
Ulnar and in- 
ternal cuta- 
neous nerves. 
SUPERIOR 
“profunda 
Behind. 
Musculo-spiral nerve. 
Superior profunda artery. 
Triceps and brachialis muscles. 
Variations.—High division of the brachial 
is frequently seen, and has been noted at all 
parts of its course. The vessel given off 
high up is usually the radial, sometimes the 
ulnar, rarely the interosseous. 
Surgical Anatomy (Fig. 458).—The brachial 
artery maybe exposed for ligation in any part 
of its course. The vessel is superficially sit- 
uated and readily exposed, the landmarks 
being the inner border of the coraco-brachialis 
muscle in the upper part of the arm, and the 
inner border of the biceps in the middle and 
lower portions of its course. An incision is 
made two inches in length parallel with the 
inner border of those muscles, the skin, super- 
ficial fascia and deep fascia are divided, and 
the artery is exposed. In the superficial fascia 
the basilic vein often lies in the course of the 
-ULNAR 
RADIAL- 
artery; the median nerve is usually superficial, 
external above and internal below ; the ulnar 
nerve is internal, and the vessel is accompanied 
by veme comites. 
Fig. 459.—Brachial artery. (Testut.) 
The Branches of the brachial are the superior profunda, muscular, nutrient, 
inferior profunda, and anastoraotica rnagna. The superior profunda accompanies 
the musculo-spiral nerve in the musculo-spiral groove between the internal and 
external heads of the triceps. Above the elbow it winds to the anterior surface 
of the forearm, and anastomoses with the recurrent branches of the arteries of the 
forearm. Muscular branches are given off to the muscles of the arm. The nutrient 
branch is given off to the humerus, entering the nutrient foramen in the shaft of 
the bone. The inferior profunda artery accompanies the ulnar nerve to the pos- 
terior surface of the elbow, and anastomoses with the recurrent branches of the 
arteries of the forearm. The anastomotica rnagna arises from the brachial two 
inches above the elbow, winds backward to the posterior surface of the internal 
condyle, and anastomoses with the recurrent branches of the arteries of the 
forearm. THE ARTERIES. 
417 
The Ulnar Artery (Figs. 462-465.) 
The ulnar artery arises as one of the terminal branches of the brachial half an 
inch below the bend of the elbow, and passes inward and downward along the 
anterior and inner portion of the forearm, between the two layers of muscles on 
Fig 460 —Horizontal section at middle of right arm—upper surface of lower segment. B. V., basilic vein; 
OF.PH V c’pohalic vein - I C. N., internal cutaneous nerve; 1. P. A., inferior profunda artery; M. C. N., mus- 
culo-cutaneous nerve ; M. N., median nerve ; M. S. N., musculo-spiral nerve; S. P. A., superior profunda artery; 
U. K, ulnar nerve. (After Braune.) 
its anterior surface. It becomes superficial in the lower part of the forearm, and 
occupies a position between the tendons ol the flexoi carpi ulnans and flexor sub- 
limis. Reaching the wrist it passes over the anterior annular ligament into the 
palm of the hand, and forms the superficial palmar arch. 
Relations of the Ulnar Artery. 
In front. 
Skin, superficial and deep fasciae. 
Superficial layer of anterior muscles of forearm. 
Internally. 
Flexor carpi ulnaris. 
Ulnar nerve. 
Externally. 
Ulnar 
artery. 
Flexor sublimis digito- 
rum. 
Behind. 
Brachialis. 
Flexor profundus digitorum. 418 
THE BLOOD-VASCULAR SYSTEM. 
Variations.—The ulnar often arises from the brachial in the arm, and some- 
times even from the axillary. The vessel is occasionally superficially situated, 
being in front of the superficial flexor muscles instead of covered by them. 
Surgical Anatomy (Fig. 463).—The ulnar artery can be exposed for ligation 
in any part of its course, the muscle and tendon of the flexor carpi ulnaris being 
the guide for finding the vessel. In the upper part of its course the artery is 
covered by the superficial flexor muscles, and, in order to reach it after dividing 
the skin and superficial fascia, the flexor 
carpi ulnaris is separated from the rest 
of the group, and the artery is exposed, 
with its venae comites, the ulnar nerve 
being to the outer side. In the lower 
half of its course the artery is superficial, 
and can be exposed by an incision made 
along the outer border of the tendon of 
SUPERIOR 
PROFUN DA 
MUSCULO- 
SPIRAL NERVE 
INFERIOR 
profunda" 
ANASTOMOTICA 
MAGNA 
ULNAR., 
nerve" 
POSTER IO R \ 
ULNAR - 
RECURRENT 
POSTERIOR 
INTEROSSEOUS 
RECURRENT 
Fig. 461.—Anastomoses at the back of the elbow, 
(Testut.) 
the elbow. (Testut.) 
the flexor carpi ulnaris, which should divide the skin, superficial fascia, and deep 
fascia. The artery is here accompanied by the ulnar nerve which is internal and 
also by venge comites. 
The Branches of the ulnar are divided into three groups, those in the forearm, 
those in the wrist, and those in the hand. 
In the forearm the branches are the recurrent arteries, anterior and posterior, 
the interosseous, and the muscular. The recurrent branches wind upward 
and inward, the anterior in front and the posterior behind the inner condyle, 
to anastomose with the inferior profunda and anastomotica magna branches of 
the brachial. The interosseous is a short trunk which divides into two branches. 
The anterior interosseous passes downward on the anterior surface of the inter- 
osseous membrane to the carpus, and supplies the deep layer of muscles. The 
posterior interosseous arises above the upper margin of the interosseous membrane, 
to the posterior surface of which it runs ; here it gives off* an ascending, or recur- 
rent, branch, which passes up to the posterior surface of the internal condyle to THE ARTERIES. 
419 
BRACHIALIS- 
BRACHIAL ARTERY WITH 
VEN/E COMITES 
MEDIAN NERVE 
MUSCULO-CUTANEOUS - 
NERVE 
BRACHIO-RADIALIS 
BICEPS 
BICIPITAL FASCIA 
MEDIAN-BASILIC VEIN 
INTERNAL CUTANEOUS 
NERVE 
RADIAL ARTERY WITH’ 
VEN/E COMITES 
RADIAL NERVE 
FLEXOR SUBLIMIS 
DIGITORUM 
FLEXOR CARPI ULNARIS 
B RAC HIO-RADIALIS- 
FLEXOR PROFUNDUS 
DIGITORUM 
PRONATOR TERES^ 
ULNAR ARTERY 
ULNAR NERVE 
FLEXOR CARPI RADIALIS^ 
RADIAL ARTERY WITH. 
VEN/E COMITES 
ULNAR NERVE 
ULNAR ARTERY 
RADIAL NERVE- 
FLEXOR SUBLIMIS 
DIGITORUM 
FLEXOR LONGUS.. 
POLLICIS 
FLEXOR CARPI ULNARIS 
BRACHIO-RADIALIS' 
FLEXOR CARPI RADIALIS' 
.ULNAR NERVE 
RADIAL ARTERY 
ULNAR ARTERY 
FLEXOR CARPI RADIALIS"" 
EXTENSORES OSSIS METACARPI 
AND BREVIS POLLICI 
ANTERIOR ANNULAR 
ligament 
SUPERFICIALIS VOL/E 
ARTERY 
FLEXOR CARPI ULNARIS 
PISIFORM 
PALMAR IS BREVIS 
Fig. 463.—Surgical relations of the radial and ulnar arteries. (Kocher.) 420 
THE BLOOD-VASCULAB SYSTEM. 
anastomose with the profunda arteries and the anastomotica magna of the brachial; 
the main portion of the posterior interosseous passes downward to the wrist 
between the superficial and deep layers of muscles of the forearm. 
In the wrist the ulnar gives off anterior and 'posterior carpal branches; these 
branches anastomose with similar branches of the radial and supply the carpus; 
the posterior carpal of the ulnar with the posterior carpal branch of the radial 
form on the back of the carpus the posterior carpal arch, which sends branches to 
the interosseous spaces and the fingers. 
In the hand the ulnar divides into the deep palmar and the superficial palmar, 
which latter forms with the superficialis volse of the radial, the superficial palmar 
arch (Fig. 464). The deep palmar branch passes between the flexor brevis and 
the abductor minimi digit! to reach the radial, which it assists in forming the deep 
DEEP 
PALMAR 
RADIAL) S 
I N DICIS 
Fig. 464.—Superficial palmar arch and its branches. (Testut.) 
palmar arch. The superficial palmar arch is situated between the palmar fascia 
and the flexor tendons at a point in the hand a little above the web of the thumb. 
The branches of the arch are the four digital arteries, of which the inner one sup- 
plies the inner side of the little finger, the second the contiguous sides of the little 
and ring fingers, the third the contiguous sides of the ring and middle fingers, and THE ARTERIES. 
421 
the fourth the contiguous sides of the middle and index fingers ; opposite the wcl> 
of the fingers the arteries are joined by the interosseous branches from the deep 
palmar arch. 
The Radial Artery (Figs. 462, 465). 
The radial artery arises from the brachial a half inch below the bend of the 
elbow. It passes downward along the radial side of the forearm, internal to the 
muscular belly and tendon of the brachio-radialis muscle ; a little above the wrist- 
joint it winds around the lower end of the radius to the posterior surface of the 
carpus ; then passes into the hand at the base of the first interosseous space, and 
forms the deep palmar arch by anastomosing with the communicating or deep 
palmar branch of the ulnar. 
Relations op the Radial in the Forearm 
In front. 
Skin, superficial and deep fasciae, belly 
of brachio-radialis. 
Internally. 
Pronator radii 
teres. 
Radial 
artery. 
Externally. 
Brachio - radi- 
al is. 
Flexor carpi 
radialis. 
Radial nerve. 
Behind. 
Radius covered by supinator. 
Flexor sublimis digitorum. 
Pronator teres. 
Flexor longus pollicis. 
Pronator quadratus. 
Variations.—The radial frequently 
springs from the brachial in the arm, and 
may even arise from the axillary. Some- 
times it is very small, its place being 
taken by branches from the ulnar and 
interosseous, and in this case it may be 
that no pulse can be found in the usual 
position. 
Surgical Anatomy (Fig. 463).—The 
radial can be exposed for ligation in any 
part of the forearm by an incision along 
the inner border of the brachio-radialis 
muscle, its belly above, its tendon below; 
after dividing the skin, superficial and 
deep fasciae, the muscle is drawn to the 
outer side and the artery exposed, ac- 
companied by vcme coraites and by the 
radial nerve, which is external. 
Branches.—The branches of the ra- 
dial are divided into three groups : those 
in the forearm, those in the wrist, and 
those in the hand. 
(Testut.) 
Fig. 465.—Arteries of the forearm—front vierr. 
The branches in the forearm are radial recurrent, muscular, anterior radial 
carpal, and the superficialis volse. The radial recurrent passes upward between 
the brachialis and the brachio-radialis to the anterior aspect of the external con- 422 
THE EL O 01)- VA BCULA It SYSTEM. 
dyle, where it anastomoses with the superior profunda of the brachial. Mus- 
cular branches are given off from the radial to the muscles of the forearm with 
which it is in contact. The anterior carpal branch of the radial supplies the 
anterior surface of the carpus, anastomosing with the anterior ulnar carpal 
artery. The superjicialis voice arises from the artery above the wrist, passes 
through the muscles of the thenar eminence, and anastomoses with the super- 
ficial palmar arch. 
The branches in the wrist are the posterior carpal, the first dorsal inter- 
osseous, the dorsal artery of the thumb, and the dorsal artery of the index finger. 
The posterior carpal (Fig. 467) supplies the posterior surface of the carpus, anas- 
tomosing with the posterior carpal branch of the ulnar. The first dorsal inter- 
osseous artery supplies the interosseous space between the index and middle 
fingers. The dorsal artery of the thumb (dorsalis pollicis) runs over the dorsal 
RADIAL ARTERY \ 
TENDON OF EXTENSOR CARPI 
I RADIALIS LONGUS 
MEDIAN NERVE 
PALMARIS 
LONGUSy 
ULNAR 
ARTERY 
ULNAR NERVE' 
Fig. 4C6.—Horizontal section at middle of right forearm—upper surface of lower segment. (After Braune.) 
aspect of the thumb, dividing into two branches, which supply both sides of the 
dorsum of the thumb. The dorsal artery of the index finger (dorsalis indicis) sup- 
plies the outer side of the dorsal surface of the index finger. 
In the hand the radial gives off the following branches—the main artery of 
the thumb (princeps pollicis), the radial artery of the index finger, the perforating, 
the interosseous, and the recurrent. The princeps pollicis passes downward in 
front of the metacarpal bone of the thumb to its head, where it divides into two 
branches, which supply the inner and outer surfaces of the thumb. The radialis 
indicis passes along the radial side of the metacarpal bone of the index finger, and 
supplies the radial side of this digit to its tip. The deep palmar arch (Fig. 468) 
is situated on the bases of the metacarpal bones, with the flexor tendons in front; 
it is completed by the anastomosing of the radial with the deep communicating 
branch of the ulnar. The deep arch is about half an inch nearer the wrist than 
the superficial. From the arch are given off the interosseous arteries, three in THE ARTERIES. 
423 
number, which run downward in the inner three interosseous spaces to join the 
digital arteries of the superficial arch above the webs of the fingers. The deep 
arch gives off also a recurrent branch to the wrist, and perforating branches, 
Fig. 467.—Arteries of the dorsum of the hand. (Testut.) 
which pierce the bases of the three inner interosseous spaces, and anastomose with 
the dorsal interosseous arteries. 
The descending aorta begins at the lower border of the fifth thoracic vertebra, 
passes downward in the thoracic and abdominal cavities in front of the spinal 
column to the fourth lumbar vertebra, where it divides into the common iliac 
arteries. It is divided into two portions, the thoracic in the chest-cavity, and 
the abdominal in the belly-cavity. 
The thoracic aorta (Fig. 469) extends from the lower border of the fifth dorsal 
THE DESCENDING AORTA. 424 
THE BLOOD-VASCULAR SYSTEM. 
vertebra to the aortic opening in the diaphragm. The vessel is at first a little to 
the left of the median line, but gradually approaches the median line at its termi- 
nation. It is in the posterior mediastinal space. 
ANTERIOR INTEROSSEOUS 
SU PER FICIA- 
LIS VOL£ 
-DEE? PALMAR 
Fig. 468.—The deep palmar arch and its branches. The first metacarpal bone has been disarticulated to 
show the course of the radial around the wrist. (Testut.) 
Relations of the Thoracic Aorta. 
Root of the left lung. 
(Esophagus. 
In front. 
Pericardium. 
Right side. 
Left side. 
(Esophagus above 
Thoracic duct. 
Thoracic 
aorta. 
Pleura and lung. 
(Esophagus below. 
Behind. 
Thoracic vertebrae. THE ARTERIES. 
425 
Variations.—Variations are often found in the number of intercostal arteries 
given off from the aorta ; frequently the arteries of two or more intercostal spaces 
are given off by a common trunk. A few cases are reported of obliteration of 
the aorta below the ductus arteriosus. These cases are consistent with life, a col- 
lateral circulation existing between the intercostals and branches given off from 
the great arteries springing from the arch above the point of obliteration, and 
between the internal mammary and the deep epigastric. 
Surgical Anatomy,—The relations of the thoracic aorta should be studied with 
special reference to the pressure symptoms occurring in aneurism. The aneurism 
may by pressure produce absorption of the bodies of the thoracic vertebrae, may 
produce pain by pressure on the spinal 
nerves and the sympathetic nerves, may 
produce difficult deglutition by pressure 
on the oesophagus. The oesophagus is at 
first at the right of the vessel, then crosses 
in front of the vessel to occupy a position 
to the left below. By pressure on the 
thoracic duct, root of the left lung, the 
heart, and the great vessels, an aneurism 
may interfere with the function of these 
structures. 
Branches.—The branches of the thora- 
cic aorta are the pericardial, bronchial, 
oesophageal, posterior mediastinal, and 
intercostal arteries. 
The pericardial are vessels of small 
size which supply the pericardium. The 
bronchial arteries supply the lung struct- 
ure with arterial blood. There are 
usually one or two vessels for each side, 
as a rule one for the right and two for 
the left. In addition to supplying the 
kino's the bronchial arteries send branches 
c? 
to the bronchial lymphatic nodes, the 
pericardium, and the oesophagus. The 
oesophageal arteries are small vessels, 
from three to five in number, given off 
from the course of the thoracic aorta, and 
supplying the oesophagus. The posterior 
mediastinal are small vessels of little 
moment, which pass backward to the 
thoracic vertebrae, and supply the lymph- 
atic nodes in the posterior mediastinum, 
and also the posterior portion of the 
diaphragm. The intercostal arteries arise 
from the posterior and lateral surfaces of 
Fig. 469.—Thoracic aorta. (Testut.) 
the thoracic aorta and run outward to the intercostal spaces ; they vary from nine 
to eleven in number. The upper two intercostal spaces are supplied, as already 
described, by the superior intercostal branch of the subclavian. Often, however, an 
aortic intercostal is sent to the second intercostal space. These vessels run in, or 
just below, the well-marked intercostal grooves on the inner surfaces and lower 
borders of the ribs ; and running forward in the intercostal spaces to the anterior 
chest wall, they anastomose with the intercostal branches from the internal mam- 
mary and musculo-phrenic. In their course the intercostals give off posterior 
branches which pass backward through the intercostal space to reach the deep 
muscles of the back, which they supply. Spinal branches to the cord and its 
membranes and to the vertebral column are derived from these. The collateral 426 
THE BLOOD-VASCULAR SYSTEM. 
intercostal branch runs from the main artery at a point opposite the angle of the 
rib to the upper border of the rib below and runs forward in the intercostal space ; 
this branch is much smaller than the intercostal itself. In their course the inter- 
costal arteries and their branches send vessels to the thoracic walls, the parietal 
layer of the pleura, and the muscles covering the thorax ; several branches of good 
size are sent to the mammary gland, usually from the third and fourth intercostal 
arteries. 
The Abdominal Aorta (Fig. 470). 
The abdominal aorta begins at the aortic opening in the diaphragm, extends 
downward retroperitoneally on the bodies of the lumbar vertebrae, either in the 
median line or a little to the left of it, and terminates on the body of the fourth 
—PHRENIC 
-CCELI AC 
i'RIGM 
,LE FT 
-RENAL 
few## 
KIDN.#| 
SPERMATIC 
A LUMBAR VEIN- 
INFERIOR 
“MESENTERIC 
bladder! 
Fig. 470.—Abdominal aorta. (Testut.) 
lumbar by dividing into the two common iliac arteries. This point is on a line 
drawn through the highest level of the iliac crests. THE ARTERIES. 
427 
Relations of the Abdominal Aorta. 
In front. 
Peritoneum. 
Stomach, 
Pancreas. 
Duodenum. 
Splenic vein. 
Left renal vein. 
Intestines. 
Solar plexus. 
Right side. 
Left side. 
Inferior vena cava. 
Thoracic duct. 
Right crus of diaphragm. 
Right semilunar ganglion. 
Abdominal 
aorta. 
Left crus of diaphragm. 
Left semilunar ganglion. 
Tail of pancreas. 
Behind. 
Vertebral column. 
Receptaculum chyli. 
Thoracic duct. 
Variations.—These are commonly variations in length ; the vessel has been 
found to divide on the third lumbar or on the fifth lumbar, above or below the 
usual point. 
Surgical Anatomy.—Aneurism of the abdominal aorta is frequently met with ; 
the relations of the aorta to surrounding structures should be carefully studied in 
order to interpret the pressure symptoms which may arise. By pressure on the 
lumbar vertebrae atrophy and .absorption of the bodies may result. Pressure on 
the spinal nerves and the sympathetic system produces pain and interference with 
the function of the structures and organs supplied by these nerves. The normal 
abdominal aorta in thin subjects is very readily outlined, and its pulsations dis- 
tinctly felt, and with the pressure of a stethoscope a murmur can be often pro- 
duced and heard, which must not be mistaken for aneurism. Ligation of the 
abdominal aorta has been performed, but always with fatal result. Successful 
cases of treating aneurism, by mechanical pressure and by operative interference 
in which silver wire was introduced into the sac, are recorded. 
Branches.—The branches of the abdominal aorta can well be divided into two 
groups—a visceral group to the viscera of the abdominal and in part to the pelvic 
cavities, and a parietal group to the walls of the abdominal cavity. The visceral 
group consists of the coeliac axis, the superior mesenteric, the inferior mesenteric, 
the suprarenal, the renal, and the spermatic. The parietal group consists of the 
phrenic, the lumbar, and the sacra media. 
The Coeliac Axis is given off from the abdominal aorta just below the aortic 
opening in the diaphragm ; it is a large short trunk, about a half inch in length, 
and divides into the gastric, the hepatic, and the splenic arteries. 
The gastric artery (Fig. 471) runs from the cceliac axis upward and to the left 
to the oesophageal orifice of the stomach ; thence it passes from left to right along 
the small curvature of the stomach to the pyloric opening. In the first part of 
its course it gives off branches to the oesophagus. The vessel is the smallest 
branch of the coeliac axis. 
The hepatic artery passes transversely to the right to the right free edge of 
the small omentum ; thence it passes upward in front of the foramen of Winslow 
to the transverse fissure of the liver, and divides into two branches to supply the 
right and left lobes of the liver. 
Variations.—The hepatic artery is sometimes a separate trunk from the aorta; 
sometimes an accessory hepatic artery is given off from the gastric, usually sup- 
plying the left lobe of the liver. 428 
THE BLOOD-VASCULAR SYSTEM. 
Surgical Anatomy.—The position of the hepatic artery and its relation to the 
common bile-duct and the portal vein must be carefully studied in operations on 
the common duct. These structures all lie in the free edge of the small omentum, 
which bounds the foramen of Winslow in front. The common duct is in front, 
the hepatic artery is to the left, and the portal vein is behind. 
Branches.—The branches of the hepatic are the pyloric, the gastro-duodenalis, 
and the cystic arteries. The pyloric branch passes to the pyloric end of the 
stomach, anastomosing with the pyloric branches from the gastric artery. The 
gastro-duodenalis is a short, large vessel which passes downward and to the right 
Fig. 471.—Arteries of the stomach, liver, and great omentum. (Testut.) 
between the head of the pancreas and the duodenum, and divides into the gastro- 
epiploica dextra and the superior pancreatico-duodenalis. The gastro-epiploica 
dextra, a vessel of large size, winds from right to left along the great curvature of 
the stomach between the folds of the great omentum, supplies the stomach and 
anastomoses with the gastro-epiploica sinistra of the splenic. The superior pan- 
creatico-duodenalis, a small vessel, winds downward between the head of the pan- 
creas and the duodenum, supplying these structures and anastomosing with the 
pancreatico-duodenalis inferior of the superior mesenteric. The cystic artery or 
arteries are usually branches of the right hepatic; they supply the gall-bladder. 
The Splenic Artery is the largest branch of the coeliac axis ; it runs from right THE ARTERIES. 
429 
to left along the upper surface of the pancreas to the spleen, where it breaks up 
into a number of branches which enter the hilum and supply that organ. 
Variations.—The splenic sometimes gives otf a hepatic branch to the left 
lobe of the liver, and, rarely, branches to the intestines. 
Surgical Anatomy.—The position of the splenic artery should be carefully 
studied with reference to the operation of removal of the spleen. The fact that 
the artery does not enter the spleen as a single trunk, but as several branches, 
and often that these vessels enter the spleen at wide distances from each other, 
should be carefully noted. 
Branches of the splenic artery are the pancreatic, the short gastric, and the 
gastro-epiploica sinistra. The 'pancreatic are numerous branches supplying the 
pancreas ; one large trunk accompanies the main duct of the pancreas from left to 
right, and is called the pancrcatica magna. The short gastric, half a dozen ves- 
sels of small size, supply the left extremity of the stomach. The gastro-epiploica 
sinistra winds along the great curvature of the stomach, and anastomoses with the 
gastro-epiploica dextra. 
The Superior Mesenteric (Fig. 472).—The superior mesenteric arises from the 
Fig. 472.—Superior mesenteric artery. (Testut.) 
anterior surface of the abdominal aorta below the coeliac axis and behind the pan- 
creas. It passes downward between the folds of the mesentery, and breaks up 
into branches which supply the small intestines, the caecum, and the ascending 
and transverse colon. 
Variations.—The superior mesenteric sometimes gives otf a hepatic branch, 
and sometimes supplies the descending colon. 430 
THE BLOOD-VASCULAIi SYSTEM. 
Surgical Anatomy.—The position of the mesenteric branches in the mesentery 
should be carefully noted in operations for the removal of sections of the intes- 
tines. Although the branches anastomose freely in the mesentery, when they 
reach the intestine and are distributed to it, they wind between its walls at right 
angles to its long axis, and do not anastomose freely with each other ; and, as a 
result of this fact, a separation of the mesentery for any considerable extent from 
the intestine cuts off the blood supply of the gut, and gangrene results. 
The Branches of the superior mesenteric are the inferior pancreatico-duo- 
denalis, the intestinal and the colic arteries. The inferior pancreatico-duodenalis 
runs between the head of the pancreas and the duodenum, supplying those struct- 
ures, and anastomosing with the pancreatico-duodenalis superior. The intestinal 
branches supply all of the small intestines except the duodenum. The colic 
branches are divided into the ileo-colic, the colica dextra or right colic, and the 
colica media or middle colic. The ileo-colic supplies the csecurn, the ileum adjoin- 
ing it, and the appendix. The right colic supplies the ascending colon ; the mid- 
dle colic, the transverse colon, and anastomoses with the left colic. 
_ INFERIOR 
MESENTERIC 
HEMORRHOIDAL 
INFERIOR < 
HEMORRHOIDAL 
Fig. 473.—Inferior mesenteric artery. (Testut.) 
The Inferior Mesenteric (Fig. 473).—The inferior mesenteric arises about an 
inch and a half above the termination of the aorta. It passes between the layers 
of the meso-colon and supplies the left portion of the transverse colon, the 
descending colon, and the sigmoid colon. 
Variations.—The inferior mesenteric is occasionally absent, its place being 
supplied by branches from the superior mesenteric. THE ARTERIES. 
431 
Surgical Anatomy.—The distribution and position of the superior hemorrhoidal 
branch and the blood supply of the rectum should be carefully studied in opera- 
tions for removal of the rectum. 
Branches of the inferior mesenteric are the left colic or colica sinistra, the sig- 
moid, and the superior hemorrhoidal. The left colic supplies the descending 
colon, and anastomoses with the middle colic of the superior mesenteric and with 
the sigmoid branch. The sigmoid supplies the sigmoid colon, and anastomoses 
with the left colon and the superior hemorrhoidal. The superior hemorrhoidal is 
a vessel of some size which passes down between the folds of the meso-rectum to 
the rectum ; it then divides into two vessels which run on either side of the 
bowel for some distance, finally perforate the muscular coat, and divide into 
branches which run down the bowel beneath the mucous membrane to its lower 
end, and anastomose with the middle and inferior hemorrhoidal. 
The Suprarenal Artery.—The suprarenal are vessels of small size, which arise 
from the lateral surfaces of the aorta opposite to the origin of the superior mesen- 
teric, and pass transversely outward to the suprarenal bodies, which they supply. 
The Renal Artery.—The renal arteries are vessels of very large size, which 
arise from the lateral surface of the aorta about half an inch below the origin of 
the superior mesenteric. They pass transversely outward to the hilum of the kid- 
neys, where they rapidly break up into branches supplying this organ. In their 
course they are in contact with the renal vein in front and the ureter behind. 
Variations.—Frequently an additional renal artery exists, and there may be 
several renal arteries. 
Surgical Anatomy.—The position of the renal artery should be carefully 
studied in the operations on the kidney. In extirpation of the kidney it should 
be remembered that more than one renal artery occurs in about one out of five 
cases. 
The Spermatic Artery.—The spermatic artery arises from the anterior surface 
of the aorta below the renal artery; it passes downward behind the peritoneum 
and in front of the psoas magnus muscle ; it crosses the ureter, enters the inter- 
nal abdominal ring and forms one of the structures of the cord ; it is distributed 
to the testicle. 
Variations.—The spermatic is sometimes a branch of the renal, sometimes two 
spermatic arteries occur on each side, sometimes both spermatics arise from a 
common trunk. 
Surgical Anatomy.—ln operations on or about the cord, as in castration, the 
position of the artery should be carefully noted. 
The Ovarian Artery of the female corresponds to the spermatic of the male. It 
takes the same course behind the peritoneum, but as it reaches the broad ligament 
it passes between its folds to the ovary, and sends a branch of some size to the 
uterus. 
Variations.—The same variations are noted in the ovarian as those described 
as occurring in the spermatic. 
Surgical Anatomy.—The position and relations of the ovarian artery should be 
carefully studied with reference to the many operations in which the broad liga- 
ment is involved. 
The Phrenic Arteries arise from the aorta above the coeliac axis, sometimes as 
a single trunk. They pass upward to the diaphragm, which they supply, and 
they anastomose with the musculo-phrenic and superior phrenic branches of the 
internal mammary. 
Variations.—The origin of the phrenic arteries varies greatly : they may arise 
as a single trunk or as separate vessels from the aorta, or from the coeliac axis. 
The Lumbar Arteries correspond to the intercostals. They are four or five in 
number on each side, and arise from the postero-lateral surface of the aorta. 
Passing outward behind the psoas magnus muscle, between the transverse pro- 
cesses of the lumbar vertebrae, each divides into a dorsal and an abdominal branch. 
The dorsal branch passes backward, supplies the deep muscles of the back, and 432 
THE BLOOD-VASCULAR SYSTEM. 
gives off a spinal branch, which furnishes branches to the spinal cord and mem- 
branes and to the lumbar vertebrae. The abdominal branch passes either in front 
of or behind the quadratus lumborum muscle to the muscles of the abdominal 
walls, winds forward, and anastomoses with the intercostal arteries and branches 
from the external iliac, which supply the walls of the abdomen. 
Variations of the lumbar arteries are not common. Two or more of the 
arteries are at times found to arise by a common trunk. 
Surgical Anatomy.—ln the operations to expose the kidney by lumbar incision, 
the position of the lumbar arteries should be remembered. 
The Sacra Media (middle sacral) artery arises from the lower end of the 
abdominal aorta, passes down the middle line of the last lumbar vertebra and 
sacrum, and to the tip of the coccyx, where it terminates in the structure 
known as Luschka’s gland. It anastomoses freely in front of the sacrum with 
the lateral sacral arteries, and gives some branches to the rectum. 
Variations.—The middle sacral is sometimes a branch from a lumbar artery, 
sometimes from the common iliac. 
Surgical Anatomy.—ln the operation known as Kraske’s operation, where the 
lower portion of the sacrum is removed, this artery is to be regarded. 
THE COMMON ILIAC ARTERIES (Figs. 470, 474). 
The common iliac arteries take their origin from the aorta where it bifurcates 
opposite the fourth lumbar vertebra. They pass downward and outward behind 
ILIO- 
LUMBAR 
LATERAL 
SACRAL 
SUPERIOR VESICAL... 
CIRCUMFLEX 
-GLUTEAL 
EPIGASTRIC' 
OBTURATOR . 
SCIATIC 
INFERIOR VESICAL 
. INTERNAL PUDIC 
-MIDDLE SACRAL 
Fig. 474.—External and internal iliac arteries. (Testut.) 
INTERNAL PUDIC^ 
the peritoneum to the articulation between the last lumbar vertebra and the sac- 
rum, and divide into the external and internal iliac arteries. 
The Relations of the common iliac arteries differ on the two sides, owing to 
the fact that the common iliac veins both pass to the ascending vena cava, which 
is to the right of the aorta. THE ARTERIES. 
433 
Relations of the Right Common Iliac. 
In front. 
Peritoneum. 
Small intestines. 
Ureter, 
Outer side. 
Right iliac vein. 
Left iliac vein. 
Inner side. 
Right common 
iliac artery. 
Psoas mannas muscle. 
o 
Ascending vena cava. 
Right iliac vein. 
Behind. 
Lower two lumbar vertebrae. 
Both common iliac veins. 
Relations of the Left Common Iliac. 
In front. 
Peritoneum. 
Small intestines. 
Ureter. 
Superior hemorrhoidal artery. 
Inner side. 
Outer side. 
Left common iliac vein 
Left common iliac 
Psoas magnus muscle. 
artery. 
Lower two lumbar vertebrae. 
Left common iliac vein. 
Behind. 
Variations.—The length of the common iliac varies with the point of bifurca- 
tion of the abdominal aorta. When the abdominal aorta bifurcates high up, as it 
does sometimes, on the third lumbar vertebra, the common iliacs are long. When 
the bifurcation is opposite the fifth lumbar we find very short common iliacs. In 
rare cases the common iliac is absent, the external and internal iliacs springing 
directly from the aorta. The common iliac sometimes gives off the middle sacral 
or a lateral sacral branch. 
Surgical Anatomy.—The common iliac has been successfully tied for aneurism 
below this point. The majority of the operations have been extraperitoneal. 
The easiest and best method, however, is the transperitoneal. An incision is 
made in the median line below the umbilicus, with the patient in the Trendelen- 
burg position ; the intestines are held up out of the way, the posterior parietal 
peritoneum is divided over the artery, and the vessel isolated and ligated. Great 
care must be taken to avoid injury to the iliac veins, which, as has been seen, 
differ in their relations to the vessel on the two sides; and the ureter, which, as a 
rule, crosses the lower portion of the vessel, must also be recognized and avoided. 
Branches.—As a rule there are no branches given off in the course of the 
vessel. (See Variations.) 
The Internal Iliac Artery (Fig. 474). 
The internal iliac artery takes its origin at the point of bifurcation of the com- 
mon iliac opposite the articulation between the last lumbar vertebra and the 
sacrum, and runs downward to the upper border of the great sacro-sciatic notch, 
where it bifurcates into an anterior and posterior trunk. 434 
THE BLOOD-VASCULAB SYSTEM. 
Relations of the Internal Iliac Artery. 
In front. 
Peritoneum. 
Ureter. 
Internal 
iliac 
artery. 
Outer side. 
Psoas magnus muscle. 
Inner side. 
Internal iliac vein. 
Internal and external iliac veins. 
Lumbosacral nerve. 
Sacrum. 
Behind. 
Variations.—The principal variations found relate to its length, which varies 
from one to three inches. Sometimes the branches are given off' from the vessel 
without a previous division into an anterior and a posterior trunk. 
Surgical Anatomy.—Ligation of the internal iliac is sometimes required. The 
ligation can be made extraperitoneally, but is best made by the same trans- 
peritoneal incision described for ligation of the common iliac. 
Branches of the internal iliac artery. From the anterior trunk are given off 
the vesical arteries, the middle hemorrhoidal, the uterine and vaginal in the 
female, the obturator, internal pudic and sciatic arteries. From the posterior 
trunk are given off the ileo-lumbar, lateral sacral, and gluteal. 
The Vesical Arteries are three in number, the superior, middle, and inferior 
vesical, which supply the bladder, prostate, and seminal vesicles. From the 
superior vesical a fibrous cord passes upward to the umbilicus. This is the 
remains of the umbilical artery, which becomes obliterated after birth. 
The Middle Hemorrhoidal Artery supplies the middle portion of the rectum, 
anastomosing with the superior hemorrhoidal, a branch from the inferior mesen- 
teric, and with the inferior hemorrhoidal, a branch from the internal pudic. 
The Uterine Arteries are vessels of good size which run to the neck of the 
uterus, ascend along its lateral wall in the folds of the broad ligament to the 
fundus, and anastomose with the ovarian and vaginal arteries. 
The Vaginal Arteries are, as a rule, two or three branches which supply the 
vaginal walls. 
Surgical Anatomy.—The position of the uterine artery and its relations to the 
uterus and the broad ligament should be carefully studied in connection with the 
many operations performed on the uterus and its appendages. 
The Obturator Artery runs downward and forward to the upper part of the 
obturator foramen. Here it passes out of the pelvis through an opening in the 
upper part of the obturator fascia, to be distributed to the upper and inner aspect 
of the thigh. 
From the portion of the artery within the pelvis several small branches are 
given off, an iliac branch to the iliac fossa, a vesical branch to the bladder, and a 
pudic branch, which winds upward along the inner margin of the femoral ring. 
In the thigh the obturator divides into an internal and an external set of branches. 
The internal passes downward on the inner surface of the thigh to be distributed 
to the adductor muscles. The external winds outward behind the femur to be 
distributed to the external rotators of the thigh. 
Variations.—The variations of the obturator are frequent, and should be care- 
fully noted in connection with the study of femoral hernia. In almost one-third 
of dissections the vessel, instead of arising from the internal iliac, is a branch 
from the deep epigastric. In some cases it is given off from the external iliac. 
Surgical Anatomy.—When the obturator is given off from the deep epigastric, 
it winds downward to reach the obturator foramen. In the majority of cases it is THE ARTERIES. 
435 
in close contact with the iliac vein, and, therefore, would be external to a femoral 
hernia. In a small proportion of cases it winds along the inner border of the 
femoral ring and would be internal to a femoral hernia. In operations for the 
relief of strangulated femoral hernia this possibility must be borne in mind. 
The Internal Pudic Artery (Figs. 474-476) is one of the terminal branches 
into which the anterior trunk of the internal iliac divides, the other being the 
sciatic. The internal pudic supplies the perineum and the external genitals. It 
is larger in the male than in the female. The internal pudic leaves the pelvis 
..GLUTEAL 
INTERNAL. 
PUDIC 
SCIATIC- 
COMES NERVI 
ISCHIADiCI 
,J NTERNAL 
CIRCUMFLEX 
SUPERIOR 
PERFORATING 
MIDDLE 
PERFORATING 
..INFERIOR 
PERFORATING 
POPLITEAL 
Fig. 475.—Arteries of the back of the hip and thigh. (Testut.) 
through the great sacro-sciatic foramen below the pyriformis muscle, winds over 
the spine of the ischium, enters the pelvis again through the small sacro-sciatic 
foramen, runs in a groove along the ascending ramus of the ischium, enters the 
perineum, and breaks up into branches, which supply the perineum and the exter- 
nal genital organs. 
Variations.—The most frequent variation is the occurrence of an accessory 
pudic branch, which runs to the anterior angle of the outlet of the pelvis below 
the symphysis pubis, perforates the triangular ligament, and supplies branches to 
the external genitals. 436 
THE BLOOD-VASCULAR SYSTEM. 
Surgical Anatomy.—The position of the puclic artery and its branches must be 
carefully studied with reference to the many operations performed on the perineum 
and on the external genitals. In the old lateral operation for stone the artery, or 
one of its large branches, may be wounded, and give rise to serious hemorrhage. 
In external urethrotomy and in median lithotomy the roof of the membranous 
urethra should be avoided, as immediately above it lies the large artery of the 
bulb, a branch of the internal pudic. The artery can be ligated at two points of 
its course ; the first where it crosses the outer surface of the spine of the ischium, 
and second along the ascending ramus of the os pubis. 
The Branches of the internal pudic are small branches given off within the 
pelvis to the muscles with which it is in contact. In the perineum the branches 
are the inferior hemorrhoidal, superficial perineal, transverse perineal, artery of 
the bulb, artery of the corpus cavernosum, and dorsal artery of the penis. 
The inferior hemorrhoidal crosses the ischio-rectal fossa to reach the lower end 
of the bowel, to which it is distributed, as well as to the contiguous integument. 
It anastomoses with the other hemorrhoidal arteries. 
The superficial perineal winds upward and inward beneath the superficial 
perineal fascia, and supplies the superficial muscles and integument of the peri- 
neum proper. 
The transverse perineal (often a branch of the superficial perineal) runs along 
the transversus perinei to the median line to the bulb of the urethra. 
The artery of the bulb is a vessel of good size which is given off from the 
internal pudic between the layers of the triangular ligament. It passes upward 
and inward to the bulb, which it supplies. This vessel and its branches often 
give rise to troublesome or even serious hemorrhage in the operation of external 
urethrotomy or median lithotomy, in which the bulb is divided ; or the artery 
may be wounded in operations for lateral lithotomy. 
The artery of the corpus cavernosum runs upward and inward between the 
layers of the triangular ligament to the corpus cavernosum, which it supplies, 
breaking up into the cavernous spaces of that structure. 
The dorsal artery of the penis passes upward to the suspensory ligament of the 
penis, which it pierces, and runs along the fibrous sheath of the upper surface of the 
penis to the glans, which it supplies. This vessel communicates with the artery 
of the corpus cavernosum. In amputations of the penis these vessels must be 
ligated. The arteries of the corpus cavernosum are best controlled by sewing up 
the strong fibrous sheath of each corpus. The distribution of the internal pudic 
in the female is practically the same as in the male, but the vessel is smaller. The 
artery of the bulb supplies the bulbus vestibuli, and the terminal branches send 
an artery to the corpus cavernosum of the clitoris and a dorsal artery to the 
clitoris. 
The Sciatic Artery (Fig. 475) is one of the two terminal branches from the 
anterior trunk of the internal iliac. It leaves the pelvis through the great sacro- 
sciatic foramen below the pyriformis muscle, and passes down the back of the 
thigh in close company with the sciatic nerves to supply the buttock and upper 
portion of the posterior aspect of the thigh. 
Variations.—The sciatic sometimes arises by a common trunk with the gluteal. 
Rarely the sciatic is a vessel of great size, and is the main source of blood for the 
lower extremity, practically taking the place of the femoral. 
Surgical Anatomy.—The sciatic may be ligated as it leaves the pelvis. An 
incision should be made in a line drawn from the posterior superior spine of the 
ilium to the tuberosity of the ischium, the fibres of the gluteus maximus separated, 
the pyriformis muscle exposed, and beneath its lower border the sciatic artery is 
found. The same incision exposes the internal pudic, as it winds over the surface 
of the spine of the ischium. 
Branches.—Within the pelvis the artery gives off small branches to the mus- 
cles with which it is in contact. After leaving the pelvis it gives off coccygeal, 
inferior gluteal, muscular and articular branches, and a branch which accompanies THE ARTERIES. 
437 
the sciatic nerve. The coccygeal branches supply the tissues about the coccyx. 
The gluteal branches supply the lower portion of the gluteus maxiraus muscle. 
The comes nervi ischiadici supplies the great sciatic nerve, running for some dis- 
tance along its sheath. The muscular branches are distributed to the external 
rotator muscles of the thigh. The articular branches are distributed to the hip- 
joint. 
The branches from the posterior trunk of the internal iliac are the gluteal, 
ilio-lumbar, and lateral sacral. 
The Gluteal Artery (Fig. 475) is a vessel of large size which leaves the pelvis 
through the great sacro-sciatic foramen above the pyriform is muscle. It then 
divides into a superficial and deep branch. The superficial runs into the gluteus 
maximus muscle, and is distributed to its substance. The deep branch runs 
SCROTUM 
-ISCHIO-CAVERNOSUS 
•BULBO-CAVERNOSUS 
INTERNAL PUDIC 
ARTERY, VEINS 
AND NERVE 
MUSCULAR VESSELS 
.SUPERFICIAL PERI- 
NEAL VESSELS 
LEVATOR ANI 1 
SPHINCTER ANI 
EXTERNU3 
/ j MUSCULAR VESSELS 
Pig. 476.—Arteries of the perineum. (Testut.) 
/ INFERIOR HEMORRHOIDAL VESSELS 
TRANSVERSE PERINEI 
between the gluteus medius and gluteus minimus, and breaks up into two sets 
of vessels, a superior and inferior, which supply these muscles. Variations of the 
gluteal are rare. The gluteal may arise by a common trunk with the sciatic, 
or may be absent, and its place be taken by a large branch from the femoral. 
Surgical Anatomy,—The gluteal may be ligated by making an incision on a 
line drawn from the posterior superior spine of the ilium to the great trochanter. 
The fibres of the gluteus maximus are separated, and the upper border of the 
pyriforrais muscle is exposed. At about the junction of the upper and middle 
thirds of the surface-line the artery is found. 
The Ilio-Lumbar Artery passes outward behind the iliac vessels and psoas 
raagnus muscle. Behind the muscle it divides into two sets of branches ; the 
lumbar which are distributed to the psoas magnus and the quadratus lumborum 
muscles, and an iliac set, which are distributed to the iliacus muscle. 
The Lateral Sacral Arteries are two in number, sometimes arising from a com- 
mon trunk. They pass to the anterior surface of the sacrum, where they are dis- 438 
THE BLOOD-VASCULAR SYSTEM. 
tributed to the pyriform is and coccygeus muscles, and to the sacral nerves. 
Branches are sent into the anterior sacral foramina, where they supply the con- 
tents of the sacral canal and the bone. 
The External Iliac Artery (Figs. 470, 474). 
The external iliac artery arises from the division of the common iliac opposite 
the articulation between the last lumbar vertebra and the sacrum, passes down- 
ward and outward behind the peritoneum and along the inner border of the psoas 
magnus muscle to the inguinal (Poupart’s) ligament, where it becomes the 
femoral. 
Relations of the External Iliac Artery. 
In front. 
Peritoneum. 
Intestines. 
Outer side. 
Psoas magnus muscle. 
Inner side. 
External iliac vein and vas 
deferens. 
External 
iliac 
artery. 
Behind. 
External iliac vein. 
Psoas magnus muscle 
Variations.—The external iliac is sometimes of small size; its resulting 
femoral is small, and the lower extremity usually then receives a large part of its 
blood supply from a large sciatic artery. The obturator is occasionally a branch 
of the external iliac. 
Surgical Anatomy.—The first portion of the external iliac is best exposed by a 
transperitoneal incision either in the mid-line or along the outer border of the 
rectus, with the patient in Trendelenburg’s position, as in the ligation of the com- 
mon or internal iliac arteries. The lower portion of the external iliac is exposed 
best by an extraperineal operation. An incision is made above Poupart’s liga- 
ment, the layers of the abdominal muscles are separated, as in the Mcßurney 
and McArthur incision for appendicitis; the peritoneum is exposed, but not 
divided. With the fingers the peritoneum in front of the artery is pushed up out 
of the way, and the vessel exposed with its accompanying vein. Care must be 
taken not to injure the two large branches of the external iliac given off just 
above the inguinal (Poupart’s) ligament. 
Branches of the external iliac are the deep epigastric and the deep circumflex 
iliac arteries. 
The Deep Epigastric (Fig. 456) arises from the external iliac just above the 
inguinal ligament. It passes inward and a little downward at first, then upward 
and inward between the transversalis fascia and the peritoneum to the posterior 
surface of the rectus muscle, continues upward, breaking into branches in the 
substance of the rectus, and anastomoses with the superior epigastric branch of 
the internal mammary. 
Variations.—The deep epigastric may take origin higher up from the external 
iliac, from any part of its course. As already noted the deep epigastric very 
often gives off the obturator artery. 
Surgical Anatomy.—The deep epigastric artery has an important relation to 
inguinal hernia. The vessel in the first part of its course is situated between the 
two rings and will therefore be internal to an oblique hernia, and external to a 
direct hernia. Its position should be carefully noted in operations for hernia. 
The Branches of the deep epigastric are the cremasteric, pubic, and muscular 
branches. The cremasteric artery supplies the coverings of the spermatic cord. THE ARTERIES. 
439 
The pubic winds around the inner margin of the femoral ring, and anastomoses 
with a similar branch from the obturator. Muscular branches are distributed to 
the muscles of the abdominal wall. 
The Deep Circumflex Iliac Artery arises from the outer surface of the external 
iliac just above Poupart’s ligament. It runs upward and outward, covered by 
the transversalis fascia, to the anterior superior spine of the ilium. It then runs 
along the crest of the ilium to about its centre, pierces the abdominal muscles, 
and breaks up into branches supplying them. 
SUPERFICIAL EPIGASTRIC 
ANTERIOR CRURA 
NERVE 
EXTERNAL 
CIRCUMFLEX 
SUPERFICIAL EXTERNAL 
EEP EXTERNAL 
SUPERIOR EXTERNAL 
ARTICULAR 
—ANASTOMOTICA 
MAGNA 
INFERIOR EXTERNAL- 
ARTICULAR 
■INFERIOR INTERNAL 
ARTICULAR 
Fig. 477.—Femoral artery. (Testut.) 
The Femoral Artery (Fig. 477). 
The femoral artery is the continuation of the external iliac opposite the 
inguinal ligament, about midway between the superior anterior spine and the 
symphysis pubis. It passes down the anterior and inner side of the thigh and 
terminates at the opening in the adductor magnus muscle by becoming the pop- 
liteal. In about the upper half of its course it lies in a surgical region called 440 
THE BLOOD-VASCULAR SYSTEM. 
Scarpa’s triangle ; in the lower half in an aponeurotic and muscular passage, 
called Hunter’s canal. The vessel divides or rather gives oif a large branch, the 
deep femoral (profunda), about two inches below the inguinal ligament. The 
portion of the vessel above this branch is called the common femoral, and its 
continuation is called the superficial femoral. 
Relations of the Common Femoral Artery. 
Skin and superficial fascia. 
Iliac portion of fascia lata. 
In front. 
Outer side. 
Common 
femoral 
artery. 
Inner side. 
Anterior crural nerve. 
Femoral vein. 
Behind. 
Pubic portion of fascia lata. 
Psoas magnus muscle. 
Pectineus muscle. 
Capsular ligament of hip. 
The Superficial Femoral Artery. 
This vessel extends from the point at which the deep femoral branch is given 
off to the opening in the adductor magnus muscle. 
Relations of the Superficial Femoral Artery. 
In front. 
Skin and superficial fascia. 
Fascia lata. 
Sartorius muscle. 
Fibrous covering of Hunter’s canal. 
Outer side. 
Inner side. 
Long saphenous nerve. 
Vastus interims muscle. 
Femoral vein. 
Superficial 
femoral 
artery. 
Adductor longus. 
Adductor magnus. 
Sartorius. 
Behind. 
Femoral vein. 
Profunda vessels. 
Pectineus muscle. 
Adductor longus muscle. 
Adductor magnus muscle. 
Scarpa’s Triangle is a surgical region of much importance, and should be care- 
fully studied. The student is advised to draw a sketch of the triangle and its 
contents. It is bounded above by the inguinal (Poupart’s) ligament, externally 
by the sartorius muscle, internally by the adductor longus muscle. The floor of 
this space is formed by the adductor longus, adductor brevis, pectineus, psoas 
magnus, and iliacus muscles. The contents are the femoral vessels and their 
branches, and the anterior crural nerve. The space contains also the superficial 
lymphatic nodes which receive the lymph from the lower extremity. 
Hunter’s Canal is a three-sided, fibro-muscular canal, occupied by the femoral 
vessels and the internal saphenous nerve. A strong fibrous layer, extending THE ARTERIES. 
441 
in front of the vessels, and between the vastus interims on the outer side and 
adductor magnus and longns on the inner, forms its anterior boundary, and the 
muscles named make its other sides. Superficial to the canal is the sartorius 
muscle. 
Variations.—The femoral may be very small, and terminate in the upper part 
of the thigh ; and the lower limb in such cases receives its blood supply in large 
part from a very large sciatic artery. The femoral has been seen to divide into 
two vessels and then unite to form a single popliteal. Variations in branches are 
frequently noted. The circumflex arteries, one or both, are sometimes derived 
from the common femoral instead of from the profunda. The profunda is some- 
times given olf from the inner side of the vessel instead of the outer side. 
Surgical Anatomy (Fig. 478).—The femoral artery is, of course, ligated in 
-FASCIA LATA 
- FEMORAL ARTERY 
-INTERNAL SAPHENOUS 
NERVE 
-SARTORIUS 
FASCIA LATA 
"SARTORIUS 
-FEMORAL ARTERY 
-VASTUS INTERNUS 
-ADDUCTOR MAGNUS 
-SARTORIUS 
-ADDUCTOR MAGNUS 
-POPLITEAL ARTERY 
-SEMIMEMBRANOSUS 
'VASTUS INTERNUS 
'SUPERIOR INTERNAL 
ARTICULAR ARTERY 
INTERNAL SAPHENOUS 
NERVE 
Pig. 478.—Surgical relations of the femoral artery. (Kocher.) 
amputations of the upper two-thirds of the thigh, and the exact position of this 
vessel and its branches should be studied in cross-sections of the thigh. The 
student is advised to make sketches of such transverse sections at various levels, 
and learn in this way the relations of the structures as they present themselves in 442 
THE BLOOD-VASCULAR SYSTEM. 
circular amputations of the thigh. The femoral can be ligated at any part of its 
course. To ligate the common femoral make an incision in a line which bisects 
Scarpa’s triangle, passing from the middle of the base to the apex. Beginning at 
the inguinal (Poupart’s) ligament and passing downward three inches, divide skin, 
superficial and deep fascia. The common femoral will be exposed, with the vein 
situated internally and in close contact, and with the anterior crural nerve exter- 
nally, and separated from it by a distance of a half inch. 
The femoral can be ligated at the apex of Scarpa’s triangle by an incision 
along the inner border of the sartorius muscle in this position. The muscle 
FEMORAL VEIN, 
FEMORAL ARTERY 
ANTERIOR CRURAL NERVE 
SAPHENOUS VEIN 
PROFUNDA ARTERY 
EXTERNAL CUTANEOUS 
/•NERVE 
BRANCHES OF 
OBTURATOR NERVE! 
femur 
Fig. 479.—Horizontal section of the right thigh near the perineum—upper surface of the lower segment. 
(After Braune.) 
is drawn outward, the deep fascia divided, and the vessel is exposed. The vein 
is here posterior to the artery, and the internal saphenous nerve is to the outer 
side. 
The femoral can be ligated in Hunter’s canal by an incision along the outer 
border of the sartorius in this position; the sartorius is drawn inward, the fibrous 
covering of the canal divided, and the artery exposed, with the vein behind or 
external, and the internal saphenous nerve superficial and external. 
The Branches of the femoral are the superficial epigastric, superficial external THE ARTERIES. 
443 
pudic, superficial circumflex iliac, deep external pudic, profunda (deep femoral), 
muscular, and anastomotica magna arteries. 
The Superficial Circumflex Iliac is given off from the femoral just below the 
inguinal (Poupart’s) ligament. It is a vessel of small size. It runs upward and 
outward in the superficial fascia to the anterior superior spine of the ilium. 
The Superficial Epigastric is given off* immediately below the inguinal (Pou- 
part’s) ligament, and winds up over this structure to the lymphatic nodes and 
superficial structures in the inguinal region. 
The Superficial External Pudic is given off a little lower than the preceding, 
passes upward and inward, crosses the spermatic cord close to the inguinal canal, 
and supplies the integument in the hypogastric region and that of the external 
genitals. This artery is almost always divided in operations for hernia and for 
varicocele. 
The Deep External Pudic runs inward for some distance beneath the fascia lata 
to reach the perineum and external genitals, to which it is supplied. 
The Profunda (Fig. 477) or deep femoral, a branch of large size, is given off 
usually from the outer side of the femoral, two inches below the inguinal (Pou- 
part’s) ligament. It passes downward, at first external to the femoral vessels, 
then behind them to the posterior surface of the adductor longus muscle, and 
terminates by perforating the adductor magnus muscle to reach the posterior sur- 
face of the thigh. 
The branches of the profunda are the external circumflex, the internal circum- 
flex, and the perforating arteries. 
The external circumflex is given off from the outer surface of the first portion 
of the profunda. It passes outward beneath the rectus femoris muscle to the 
outer aspect of the thigh, and divides into three branches, ascending, transverse, 
and descending. The ascending passes up to the buttock, and anastomoses with 
the gluteal arteries; the transverse winds around the thigh, supplying the vastus 
externus, and vastus intermedins; the descending passes downward on the outer 
aspect of the thigh, as far as the knee. The internal circumflex (Fig. 475) is 
given off from the inner aspect of the profunda near its origin. It winds back- 
ward between the psoas and pectineus muscles to the lesser trochanter of the 
femur, near which it divides into two sets of branches, the ascending and 
transverse. The ascending follows the obturator externus to its insertion in the 
great trochanter. The transverse winds backward around the femur just below 
the great trochanter. The internal circumflex gives off also an articular branch 
to the hip-joint. The perforating arteries, three or four in number, are given off 
from the course of the profunda artery behind the adductor magnus; they jDer- 
forate the adductor magnus, reach the posterior surface of the thigh, wind around 
the femur in close contact with the bone, supply the hamstring muscles, and 
terminate in the vastus externus and vastus intermedius muscles. The nutrient 
artery of the femur is derived from the third perforating artery. Muscular 
branches are given off from the femoral in its entire course to the contiguous 
muscles. 
The Anastomotica Magna is given off from the femoral just before its termi- 
nation. The artery passes downward, and divides into two branches : a super- 
ficial branch, which accompanies the internal saphenous nerve and vein, supplying 
the integument, and a deep branch, which passes down between the vastus inter- 
nus and the adductor magnus to terminate in the popliteal space. Both branches 
anastomose with the articular branches of the popliteal artery. 
The Popliteal Artery (Fig. 480) is a continuation of the femoral. It begins at 
the opening in the adductor magnus muscle through which the femoral passes, 
extends downward through the centre of the popliteal space, resting on the femur, 
posterior ligament of the knee-joint and the popliteus muscle, to the lower border 
of the latter, where it divides into its two terminal branches, the anterior and 
posterior tibial. 444 
THE BLOOD-VASCULAR SYSTEM. 
Relations of the Popliteal Artery 
In front. 
Femur. 
Posterior ligament of knee 
Popliteus muscle. 
Inner side. 
Outer side. 
Inner hamstring muscles. 
Inner head of gastroc 
neraius. 
Biceps. 
Outer head of gastroc- 
nemius. 
Popliteal 
artery. 
Behind. 
Skin, superficial and deep fasciae. 
External saphenous vein. 
Internal popliteal nerve. 
Popliteal vein. It is partially covered, behind by the muscles forming 
the boundaries of the space. 
The Popliteal Space is the diamond-shaped area at the back of the knee- 
joint. The student is advised to make a sketch of this space, its boundaries, and 
contents. The popliteal space is bounded above by the inner hamstring inter- 
SUPERIOR INTERNAL{ 
ARTICULAR i 
__SUPERIOR EXTERNAL 
ARTICULAR 
SURAL- 
—SURAL 
.INFERIOR EXTERNAL 
ARTICULAR 
INFERIOR INTERNAL-- 
ARTICULAR 
nally, and by the outer hamstring externally. It is bounded below by the inner 
and outer heads of the gastrocnemius muscle. The floor of the space is formed 
above by the posterior surface of the femur, in the centre by the posterior liga- 
Fig. 480.—Popliteal artery. (Testut.) THE ARTERIES. 
445 
merit of the knee-joint and below by the popliteus muscles. The space contains 
the popliteal artery in close contact with its floor, the popliteal vein superficial to 
the artery and the internal popliteal nerve superficial to the vein, these structures 
being almost in the mid-line of the space. The external popliteal nerve runs 
along the outer and upper border of the space, in close contact with the biceps. 
The space contains much fat and areolar tissue, and a few lymphatic nodes. 
Variations.—The popliteal sometimes divides into three branches, the anterior 
tibial, the posterior tibial, and the peroneal; at times into the anterior tibia! and 
peroneal, the peroneal supplying the place of the posterior tibial. Sometimes a 
high division of the popliteal occurs opposite the knee-joint. 
Surgical Anatomy (Fig. 481).—The popliteal is sometimes injured in fracture 
FASCIA LATA 
"POPLITEAL NERVE 
_POPLITEAL VEIN 
-POPLITEAL ARTERY 
GASTROCNEMIUS 
” (outer head) 
GASTROCN EMIUS 
(inner head) 
_CUTAN EOUS BRANCH OF 
POPLITEAL NERVE 
pEXTERNAL SAPHENOUS 
& VEIN 
-HEAD OF FIBULA 
Fig. 481.—Surgical relations of the popliteal artery. (Kocher.) 
of the lower end of the femur. When the lower end of the femur is divided in 
operations to correct the deformity of knock-knee, the artery must be carefully 
avoided. The popliteal artery, next to the aorta, is the most common site of 
aneurism. This condition is relieved usually by pressure, or the ligation of the 
femoral, although at times the aneurismal sac is dissected out, and the artery 
ligated above and below the lesion. The popliteal can be exposed and ligated at 
any part of its course. The artery is more superficial in the upper and lower 
portions of the popliteal space than in the middle portion. In exposing the 
vessel in any part of its course the fact that the internal popliteal nerve and the 
popliteal vein are superficial to the artery must be borne in mind, and these 
structures avoided. 
The Branches of the popliteal artery are the muscular, the cutaneous, the 
articular, and the anterior and posterior tibial. The muscular are distributed 
to the muscles forming the boundaries of the popliteal space, a superior set to 
the hamstring muscles, and an inferior set to the gastrocnemius, plantaris, 
soleus, and popliteus. The cutaneous branches supply the integument over the 
calf of the leg. The articular branches are five in number : the superior inter- 
nal, the superior external, the azygos, the inferior internal, and the inferior 
external articular arteries. The superior and inferior articular arteries wind 
around the knee-joint, and form an anastomosis with each other around the 
patella. These vessels anastomose with the recurrent branches from the arteries 
of the leg, with the anastomotica magna of the femoral, and with the perforating 446 
THE BLOOD-VASCULAR SYSTEM. 
of the profunda. The azygos articular penetrates the posterior ligament of the 
knee-joint, and supplies the intra-articular ligaments and synovial membrane. 
The Posterior Tibial Artery (Fig. 482). 
The posterior tibial artery is the larger of 
the two terminal branches of the popliteal, and 
appears as though it were the continuation of the 
latter. It passes down the leg on the tibial side 
between the deep and superficial layers of mus- 
cles on the back of the leg, covered also by the 
deep transverse fascia of the leg, until it reaches 
the inner ankle, where it divides into the internal 
and external plantar arteries. The important 
points to be remembered in regard to the course 
of the posterior tibial are that it is on the tibial 
side of the leg, between the deep and superficial 
layers of muscles, covered also by the deep trans- 
verse fascia of the leg, and accompanied by the 
posterior tibial nerve and venae comites. 
ANTERIOR 
TIBIAL 
Relations of the Posterior Tibial Artery. 
In front. 
Tibialis posterior muscle. 
Flexor longus digitorum. 
Tibia. 
Ankle-joint. 
Inner side. 
Posterior 
tibial 
artery. 
Outer side. 
Vena comes. 
Vena comes. 
Skin, superficial and deep fasciae. 
Gastrocnemius. 
Sole us. 
Deep transverse fascia. 
Posterior tibial nerve. 
Behind. 
”PERONEAL 
Variations.—The posterior tibial may be 
small, its place being taken by a large peroneal 
artery. The vessel may arise from a high division 
of the popliteal. 
Surgical Anatomy (Fig. 483).—In amputa- 
tions of the leg the posterior tibial is found 
between the superficial and deep muscles on the 
tibial side. Ligations of the posterior tibial may 
be required for injury or aneurism. The vessel 
may be ligated at any part of its course. In the 
middle of the leg the artery can be exposed by 
an incision a finger’s breadth behind and parallel 
with the inner border of the tibia. The skin, 
Fig. 482,—Arteries in the dorsal part 
of the leg. (Testut.) 
superficial and deep fascise are divided, the tibial origin of the soleus is exposed 
and divided, and the deep transverse fascia, which now comes into view, is also 
divided. The vessel is found accompanied by the posterior tibial nerve and the THE ARTERIES. 
447 
vense comites. In the lower part of its course, opposite the inner ankle, the 
vessel occupies a position midway between the internal malleolus and the os calcis. 
It can be exposed by a curved incision dividing the skin, superficial and deep 
fascise, and the internal annular ligament. The position of the vessel at the inner 
ankle should be noted in making tenotomies of the tibialis posterior tendon. 
_ INTERIVTAL SAPHENOUS 
NERVE 
-INTERNAL SAPHENOUS 
VEIN 
GASTROCNEMIUS 
'DEEP FASCIA 
.INNER SURFACE OF 
DEEP FASCIA 
-POSTERIOR TIBIAL NERVE 
POSTERIOR Tl BIAL ARTERY 
SOLEUS 
FASCIA LATA 
"SOLEUS 
“DEEP FASCIA 
POSTERIOR TIBIAL NERVE 
POSTERIOR Tl BIAL ARTERY 
FLEXOR LONGUS DIG- 
ITORUWI 
INTERNAL SAPHENOUS- 
NERVE 
INTERNAL SAPHENOUS— 
VEIN 
.POSTERIOR TIBIAL VEIN 
-FLEXOR LONGUS DIG- 
ITORUM 
“POSTERIOR TIBIAL NERVE 
POSTERIOR TIBIAL ARTERY 
' FASCIA 
Fig. 483.—Surgical relations of the posterior tibial artery. (Kocher.) 
The Branches of the posterior tibial are the muscular, peroneal, nutrient, com- 
municating, internal calcanean, and its terminal branches, the internal and exter- 
nal plantar. 
The muscular are distributed to the deep layer of muscles on the back of the 
!eg. 
The Peroneal (Fig. 482) is a large artery, which is given off an inch or more 448 
THE BLOOD-VASCULAR SYSTEM. 
below the origin of the posterior tibial. It passes down the fibular side of the 
leg close to the fibula, either lying on or contained in the fibres of the flexor 
longus hallucis muscle. At the lower border of the interosseous membrane it 
gives off* an anterior peroneal branch, which runs forward to the anterior and 
outer surfaces of the ankle. The rest of the vessel is continued downward, to 
the posterior surface of the outer ankle and the os calcis. In its course the 
peroneal gives off muscular branches to the contiguous muscles, a nutrient branch 
to the fibula, a communicating branch to anastomose back of the ankle with the 
communicating branch from the posterior tibial. The vessel is accompanied by 
venae comites, but not by a nerve-trunk. 
Variations (see posterior tibial artery). 
Surgical Anatomy (Fig. 484).—The peroneal is ligated in amputations of the 
-SOLEUS 
- CUT SURFACE OF 
SOLEUS 
- GASTROCNEMIUS 
-PERONEAL ARTERY 
-PERONEUS LONGUS 
-FLEXOR LONGUS 
HALLUCIS 
-SOLEUS 
’SOLEUS 
-PERONEAL ARTERY 
PERONEUS BREVIS 
FLEXOR LONGUS 
HALLUCIS 
FLEXOR LONGUS 
HALLUCIS 
SAPHENOUS 
NERVE 
EXTERNAL SAPHENOUS 
"" VEIN 
Fig. 484.—Surgical relations of the peroneal artery. (Kocher.) 
leg. The position of the vessel on the fibular side of the leg between the deep 
and superficial muscles, or in the substance of the flexor longus hallucis, should be 
noted. The peroneal artery can be ligated in the middle portion of its course 
through an incision a finger’s breadth behind and parallel to the fibula. The THE ARTERIES. 
449 
skin, superficial and deep fascite are divided, and the fibular origin of the 
soleus then comes into view. This is divided, and the deep transverse fascia 
is exposed; this is also divided, and the artery is found accompanied by venae 
comites, either lying on or in the muscular substance of the fiexor longns hallucis. 
The nutrient artery from the poste- 
rior tibial is a vessel of large size, which 
enters the nutrient foramen in the tibia 
on its posterior surface. The com- 
municating branch passes from the pos- 
terior tibial outward just above the 
ankle-joint to anastomose with a simi- 
lar branch from the peroneal. 
The Internal Calcanean Arteries are 
given off from the posterior tibial just 
above the ankle; they supply the tis- 
sues of the heel. The position of these 
vessels is of importance in amputations, 
such as Syme’s and PirogofPs. Care 
should be taken not to injure these ves- 
sels in making the heel flap, because, 
if they are injured, sloughing is apt to 
result. 
The terminal branches of the poste- 
rior tibial are the internal and external 
plantar. 
The Internal Plantar (Fig. 485) 
arises from the posterior tibia! at the 
inner ankle, passes forward along the 
inner side of the foot, and terminates 
at the inner side of the great toe. It 
supplies the inner side of foot and great 
toe. 
The External Plantar is a vessel of 
large size; it passes outward and for- 
ward to the base of the metatarsal bone 
of the little toe, being covered by the 
plantar fascia. It then winds inward 
and forward on bases of the metatarsal 
bones to the interosseous space between 
the great and second toes, and lie re 
anastomoses with the deep, communicat- 
ing branch from the dorsalis pedis, thus 
completing the plantar arch. 
Variations.—The plantar arteries 
vary somewhat in size. In some cases 
the internal plantar is larger than usual, 
and supplies two or more toes, the ex- 
ternal plantar being correspondingly smaller. 
Penetrating wounds of the plantar arch may give rise to severe hemorrhage. 
This, however, can usually be controlled by pressure, or by a free dissection, the 
bleeding points being found and ligated. 
Fig. 485.—Arteries in the sole of the foot. (Testut.) 
The Branches of the External Plantar are small muscular, cutaneous, and 
articular branches to the contiguous muscles, integument, and joints, and the 
posterior perforating and digital branches. The 'posterior perforating are small 
trunks which perforate the second, third, and fourth interosseous spaces to com- 
municate with the dorsal interosseous arteries. The digital arteries are four in 
number, and supply the outer side of the little toe and the contiguous sides of 450 
THE BLOOD-VASCULAR SYSTEM. 
the second and third, the third and fourth, the fourth and fifth. The contiguous 
sides of the great toe and second toe will be found, in the description of the 
dorsalis pedis, to be supplied by its deep plantar branch. Opposite the web of 
the toes each digital branch gives off a perforating artery, which anastomoses 
with the dorsal interosseous arteries. 
The Anterior Tibial Artery (Fig. 486). 
The anterior tibial artery begins at the bifurcation of the popliteal, at the 
lower border of the popliteus muscle. It passes between the heads of origin of 
the tibialis posterior muscle, above 
the upper border of the interosseous 
membrane, to the anterior surface of 
the leg, runs downward on the ante- 
rior surface of the interosseous mem- 
brane, accompanied by the anterior 
tibial nerve and vense comites, and in 
a position external to the tibialis 
anterior muscle, to the bend of the 
ankle. Here the vessel becomes the 
dorsalis pedis. 
ANTERIOR TIBIALy 
RECURRENT ~M 
Relations of the Anterior 
Tibial Artery. 
ANTERIOR TIBIAL 
NERVE 
Skin, superficial and deep fasciae. 
Tibialis anterior muscle. 
Tendon of the extensor proprius pol- 
licis. 
In front. 
Inner side. 
Older side. 
Tibialis 
, . 
anterior, 
Anterior tibial 
7 
Fxtensor longus 
n. & 
disutorum. 
Extensor pro- 
prius hallucis. 
Anterior 
tibial 
ar ery. 
.MALLEOLAR 
ANTERIOR 
PERONEAL 
Interosseous membrane 
Tibia. 
Behind. 
EXTERNAL 
MALLEOLAR 
[dorsalis 
[“PEDIS 
Variations.—The anterior tibial 
may be very small, or absent, its 
place being taken by branches from 
the posterior tibial or peroneal. It 
has been seen to accompany the mus- 
Fig. 186.—Anterior tibial artery. (Testut.) 
culo-cutaneous nerve, winding around the fibula to reach the front of the leg. 
Surgical Anatomy (Fig. 487).—In amputations of the leg the anterior tibial is 
ligated. It should be noted that it lies in front of the interosseous membrane, 
and external to the tibialis anterior, and that it is accompanied by vense comites 
and the anterior tibial nerve. The anterior tibial can be ligated at any part of 
its course through an incision along the line of the outer border of the tibialis 
anterior muscle. This incision should divide the skin, superficial and deep fascise. 
The outer border of the tibialis anterior is found ; this muscle is then separated from 
the two other muscles on the front of the leg : the extensor longus digitorum and THE ARTERIES. 
451 
the extensor proprius hallucis. The artery will be found on the interosseous 
membrane, accompanied by vense comites, and with the anterior tibial nerve to 
the outer side. 
Now that the student has reviewed the arteries of the leg, it is advised that 
sketches be made of transverse sections at several levels showing the position of 
the vessels and their relation to other structures. 
TIBIALIS ANTERIOR 
ANTERIOR TIBIAL NERVE 
EXTENSOR LONGUS 
DIGITORUM 
CREST OF TIBIA 
•TIBIALIS ANTERIOR 
INTERIOR TIBIAL NERVE 
ANTERIOR TIBIAL ARTERY 
•EXTENSOR PROPRIUS 
HALLUCIS 
.EXTENSOR PROPRIUS 
HALLUCIS 
ANTERIOR TIBIAL ARTERY- 
ANTERIOR TIBIAL NERVE- 
TENDON OF EXTENSOR 
LONGUS DIGITORUM 
MUSCULO-CUTANEOUS 
NERVE 
Fig. 487.—Surgical relations of the anterior tibial artery of the right leg. (Kocher.) 
Branches of the anterior tibial are the anterior tibial recurrent, the posterior 
tibial recurrent, muscular, and the internal and external malleolar arteries. The 
posterior tibial recurrent is given off from the vessel before it gains the anterior 
aspect of the leg. It passes upward to the popliteal space, and anastomoses with 
the inferior articular branches of the popliteal. The anterior tibial recurrent is 
given off from the vessel immediately after it appears on the anterior surface of 452 
THE BLOOD-VASCULAR SYSTEM. 
the leg. It winds upward in the substance of the tibialis anterior to the patella, 
and anastomoses with the arteries forming the patellar anastomosis. Muscular 
branches are given off to the muscles on the anterior surface of the leg. The 
'malleolar arteries are small branches given off from the lower portion of the ante- 
rior tibial. The external malleolar supplies the tissues over the outer ankle, the 
internal malleolar those over the inner ankle. 
The Dorsalis Pedis (Fig. 489).—The dorsalis pedis is the continuation of the 
anterior tibial. It begins at the bend of the ankle, and continues downward and 
forward to the base of the first interosseous space, where it divides into the dor- 
POSTERIOR 
TIBIAL / 
ARTERY^ 
PLANTARIS^ 
rPhKUNtHU 
'ARTERY 
Fig. 488.—Horizontal section at middle of right leg—upper surface of lower segment. (After Braune.) 
salis hallucis and the communicating or plantar digital branch. The vessel is 
superficial in position; it is accompanied by the anterior tibial nerve and venae 
comites; it is external to the tendon of the extensor proprius hallucis. 
Variations.—The dorsalis pedis varies in size greatly; when large, it assists 
materially the plantar arteries in supplying the sole of the foot; when small, the 
plantar arteries may furnish a large part of the supply for the dorsum. 
Surgical Anatomy.—The dorsalis pedis can be exposed by an incision along the 
outer side of the tendon of the extensor proprius hallucis. It is accompanied by 
the anterior tibial nerve and by venm comites. 
The Branches of the dorsalis pedis are the tarsal, metatarsal, dorsalis hallucis, 
and communicating or plantar digital. The tarsal artery winds outward over the THE ARTERIES. 
453 
dorsal surface of the tarsal bones, supplying them and contiguous structures. 
The metatarsal winds outward over the bases of the metatarsal bones, forming an 
arch from which three interosseous branches are given off, which run forward in 
the three interosseous spaces to the webs of the toes, where they anastomose with 
the digital branches of the plantar arch. At the origin of these interosseous 
branches, perforating branches from the plantar arch communicate with each ves- 
sel. The dorsalis hallucis runs forward in the first interosseous space to the web 
INTERNAL 
“MALLEOLAR 
ANTERIO R 
PE RO NEA L 
EXTERNAL^ 
MALLEOLAR 
-COMMUNICATING 
Fig. 489.—Arteries of the dorsum of the foot. (Testut.) 
of the toes ; here it divides into two branches, supplying the contiguous sides of 
the great and second toe. The communicating or plantar digital branch perforates 
the first interosseous space to reach the plantar surface of the foot. Here it 
anastomoses with the external plantar, and completes the plantar arch. It then 
continues forward in the plantar surface of the first interosseous space to the web 
of the toes. Here it divides into two branches which supply the contiguous sur- 
faces of the great and second toes. THE VEINS. 
G. WOOLSEY. 
THE veins are the vessels through which the blood is returned from the capil- 
laries to the heart. Like the arteries, they may be divided into the pul- 
monary and the systemic. 
THE PULMONARY VEINS. 
These consist of two large, short trunks on either side, in the root of the 
corresponding lung (Fig. 490). They extend nearly horizontally inward and for- 
ward from the hilum of the lung to the upper part of the back of the left auricle. 
They lie in front of and below the corresponding pulmonary arteries, and on 
piercing the pericardium they are invested on their ventral aspect only by the 
entrance of 
-VENA AZYGOS 
BRANCH OF PUL- 
"monary artery 
P^LEFTj 
VENTRICLE 
LEFT- 
AURICLE 
Fig. 490.—Pulmonary veins, seen in a dorsal view of the heart and lungs. (Testut.) 
serous layer of that membrane. The two right pulmonary veins pass behind the 
superior vena cava, the ascending portion of the aorta, and the right auricle. The 
two left pulmonary veins pass in front of the descending portion of the aorta. They 
convey arterial blood, and have no valves. 
454 THE VEINS. 
455 
The pulmonary veins are but little larger than the arteries they accompany. 
The right superior pulmonary vein commonly receives the vein from the middle 
lobe of the right lung, but sometimes the latter continues to the auricle separately 
as a third vein. The two pulmonary veins, on a side, more often on the left, 
sometimes unite, and terminate in a single trunk. 
THE SYSTEMIC VEINS. 
These convey the blood from the capillary plexuses of the rest of the body to 
the right auricle of the heart, which most of the veins of the heart enter by the 
coronary sinus, and the veins of the remainder of the body by the superior and 
inferior vense cavse. They differ from the arteries in their larger capacity, their 
greater number, their thinner walls, their larger and frequent anastomoses, and 
the occasional presence of more or less perfect valves, which prevent backward cir- 
culation. The veins from the stomach, intestines, spleen, and pancreas differ 
from the others in that, after joining to form a single trunk, the portal vein, the 
latter breaks up in the substance of the liver into a capillary network, from which 
the blood is collected by the hepatic veins, and emptied into the inferior vena 
cava. 
The veins may be divided into two sets, the superficial and the deep, between 
which are frequent communications. The superficial or subcutaneous veins lie 
between the layers of the superficial fascia, and do not usually accompany an 
artery. The deep veins usually accompany the arteries, sometimes as a single 
trunk, as with the larger arteries (axillary, femoral, etc.), sometimes as a fre- 
quently anastomosing pair, the venae, comites, one on either side of the smaller 
arteries (radial, tibia!, etc.). 
The venous sinuses of the cranium differ from the veins in distribution and in 
structure, being formed by a separation of the two layers of the dura, and lined 
by epithelium. 
In the following pages a detailed description is necessary only for those veins 
which do not accompany an artery. The systemic veins are naturally divided 
into three groups, according as they empty into the heart through the superior or 
the inferior vena cava, or the coronary sinus. 
THE VEINS OF THE HEART. 
The cardiac or coronary veins (Fig. 491), which return the blood from the 
substance of the heart, accompany the arteries, but have not an exactly similar 
course, as the arteries start in front, while the veins empty into the coronary sinus 
behind. 
The Coronary Sinus is situated in the dorsal part of the groove between the 
left auricle and ventricle. About an inch in length, it is covered by the muscular 
fibres of the auricles, and its termination in the right auricle, between the open- 
ing of the inferior vena cava and the auriculo-ventricular aperture, is guarded by 
the coronary or Thebesian valve. Where the cardiac veins (excepting the oblique 
vein) join the coronary sinus they are guarded by valves, which are wanting in 
the rest of their course. 
The oblique vein of Marshall, which runs over the back part of the left 
auricle in the vestigial fold of the pericardium, enters the left extremity of the 
sinus without a valve. The oblique vein with the coronary sinus represents the 
left superior vena cava, or the left duct of Cuvier and part of the sinus venosus 
of the foetus. This vein is often represented in great part by a fibrous cord. 
The Great Cardiac Vein (anterior coronary vein) ascends from near the apex 
of the heart in the ventral interventricular groove to the auriculo-ventricular 
groove, in which it turns to the left and passes backward to terminate in the left 
end of the coronary sinus, which appears as the dilated continuation of this vein. 456 
THE BLOOD-VASGULAB SYSTEM. 
It accompanies first the anterior and then the posterior branch of the left coronary 
artery, and receives branches from either side of its course, one of which, ascend- 
ing along the left margin of the heart (left marginal vein) is of some size. 
The Middle Cardiac Vein (posterior interventricular vein) ascends from the apex 
of the heart in the dorsal interventricular groove to empty into the right extrem- 
•VENA AZYGOS 
MAJOR 
LEFT AURICULAR., 
APPENDIX 
PULMONARY 
VEINS 
.PULMONARY 
VEINS 
LEFT 
AURICLE 
RIGHT CORONARY ARTERY 
AURICULAR-VENTRICULAR 
GROOVE 
CORONARY. 
SINUS 
RIGHT 
AURICLE 
LEFT 
VENTRICLE' 
POSTERIOR CARDIAC’ 
VEIN 
POSTERIOR 
INTERVENTRIC 
ULAR GROOVE 
rig'Rt coronary 
ARTERY—DESCEND- 
ING BRANCH 
Fig. 491.—Cardiac veins, dorsal view. (Testut.) 
’RIGHT 
VENTRICLE 
ity of the great coronary sinus. It receives branches from the dorsal surface of 
both ventricles. 
The Posterior Cardiac Veins are three or four small vessels, which ascend on 
the dorsal surface of the left ventricle to open along the lower border of the 
coronary sinus. 
The Right or Small Coronary Vein passes along the right auriculo-ventricular 
groove to convey the blood from the hinder parts of the right auricle and ventricle 
into the right end of the coronary sinus. 
The following small vessels empty directly into the heart without the inter- 
vention of the coronary sinus. The Anterior Cardiac Veins are two or three 
small vessels, which collect the blood from the ventral surface of the right 
ventricle, and ascend to enter the lower part of the right auricle. One larger 
than the others (right marginal vein or vein of Galen) runs along near the antero- 
inferior border of the heart. The smallest cardiac veins (venae cordis minimce, 
Venae Thehesii) are numerous small veins within the substance of the heart, 
which open into some of the small foramina Thebesii in the right auricle. 
Similar veins are said to open into the other heart-cavities. 
THE SUPERIOR VENA CAVA AND ITS TRIBUTARIES (Figs. 491, 493). 
The superior (descending) vena cava is formed by the confluence of the right 
and left brachio-cephalic (innominate) veins behind the lower part of the junction 
of the first right costal cartilage with the sternum. From this point it passes 
nearly vertically downward, with a slight convexity to the right, for about three 
inches, to empty into the right auricle on a level with the third costal cartilage. 
Its lower inch and a half are contained within the pericardium, the serous layer 
of which invests it except along its hind border. It receives the blood returned THE VEINS. 
457 
from the head, neck, upper extremities and thoracic walls. It contains no valves. 
Relations.—On its right side are the right lung and pleura, with the phrenic nerve 
between. On its left side lies the brachio-cephalic artery above, and the ascending 
portion of the aortic arch below. In front it is overlapped by the right pleura 
and lung. The root of the right lung lies behind, it. 
Its lateral tributaries are the great azygos vein, which enters it just before it 
penetrates the pericardium, and small veins from the pericardium and mediastinum. 
The Brachio-cephalic Veins. 
The brachio-cephalic or innominate veins return the blood from the head, neck, 
upper extremities, and a part of the thoracic walls. They are formed by the 
union of the subclavian and internal jugular veins, behind the sternal end of each 
clavicle, and unite below, opposite the lower border of the first right costal car- 
tilage, at its junction with the sternum, to form the superior vena cava. At the 
angle of junction of the subclavian and jugular veins there open into the venous 
circulation the thoracic duct on the left side and the right lymphatic duct on the 
right side. There are no valves in the brachio-cephalic veins. 
The Right Brachio-cephalic Vein, only about an inch in length, descends nearly 
vertically on the outer side of, and superficial to, the brachio-cephalic and the 
commencement of the subclavian arteries. The right lung and pleura lie on its 
right side and in front, with the phrenic nerve between. 
The Left Brachio-cephalic Vein, two and a half to three inches long, passes 
from left to right with a slight downward inclination to join the right vein. In 
front of it lies the upper part of the manubrium sterni, Avith the lower ends of 
the sternal muscles, below it the arch of the aorta, and behind it the three 
branches of the arch, and the left phrenic and pnenmogastric nerves. 
Lateral Tributaries.—Each brachio-cephalic vein receiA7es the vertebral, 
inferior thyroid, and internal mammary veins of its oavh side, and, in addition, 
the left vein receives the left superior intercostal vein, and small thymic, medi- 
astinal, and pericardial branches. 
Variations in the Superior Vena Cava and, Brachio-cephalic Veins.—These are 
mostly due to a persistence of the left duct of Cuvier of the foetus, which may form 
a left superior vena cava. This descends from the commencement of the left 
brachio-cephalic vein, in front of the aortic arch and the root of the left lung, 
to the heart, Avhere it is continued in the usual position of the coronary sinus to 
open into the right auricle. The usual left brachio-cephalic vein may persist 
as a small communicating branch betAveen the right and left superior venae cavse, 
or it may be altogether wanting. In a few cases besides those of transposition 
of the viscera the superior vena caATa is found on the left side, the right brachio- 
cephalic vein taking a transverse course similar to that usually taken by the left. 
Veins of the Head and Neck. 
I. Veins of the Surface of the Head and Face (Fig. 492). 
The superficial veins of the face and the fore part of the head and the deep 
veins of the face unite to form tAVO trunks, the facial and the tempero-maxillary 
veins, while the occipital and posterior auricular veins collect the blood from the 
hind part of the scalp. Valves are generally absent in the ATeins of the head and 
neck, except at the loAver end of the internal and external jugular ATeins. 
The Facial Vein (anterior facial) collects the blood from the fore part of the 
face and scalp. It commences at the side of the nose, on a line with the lower 
margin of the orbit, as the direct continuation of the angular vein. It is less 
A. ANTERIOR REGION 458 
THE BLOOD-VASCULAR SYSTEM. 
tortuous than the facial artery, behind which it passes downward and outward to 
and around the lower border of the jaw, in front of the masseter muscle. Below 
the lower border of the jaw it inclines backward beneath the platysma muscle, 
to empty into the internal jugular vein near the level of the hyoid bone. Below 
the digastric muscle it is joined by the anterior division of the temporo-maxillary 
vein, and the trunk thus formed is called the common facial vein. A communi- 
.ANGULAR 
SUPERIOR 
THYROID 
JUGULAR 
eating branch passes downward along the ventral margin of the sterno-mastoid 
muscle to join the anterior jugular vein. 
The Angular Vein, on each side, lies along the side of the root of the nose 
from a point a little below the level of the eyebrow, where it is formed by the 
junction of the frontal and supra-orbital veins, to the lower margin of the orbit, 
where it becomes the facial vein. It appears as the continuation of the frontal 
vein, lies internal to the lachrymal sac, receives branches from the nose and upper 
eyelid, and communicates with the superior ophthalmic vein. 
Fig. 492.—Superficial veins of the cranium and face, right lateral view. (Testut.) THE VEINS, 
459 
The Transverse Nasal Vein arches across the bridge of the nose, and unites the 
two angular veins, or the lower ends of the frontal veins. 
The Frontal Vein is formed by branches from the forehead and the forepart of 
the scalp, which communicate with the anterior division of the temporal vein. 
These tributaries pass downward and inward to form a trunk which, connected 
with its fellow by cross-branches, descends nearly vertically on the side of the 
median line to a point a little below the inner end of the eyebrow, where it is 
joined by the supra-orbital vein and becomes the angular vein. The right and 
left frontal veins sometimes unite into a single median trunk, which bifurcates at 
the root of the nose into the two angular veins. 
The Supra-orbital Vein is a smaller vessel which collects the blood from the 
lower and lateral part of the forehead, upper eyelids, etc., and passes obliquely 
downward and inward to join with the frontal vein in forming the angular. It 
communicates laterally with the temporal, and dorsally with the ophthalmic vein 
and the frontal vein of the diploe. 
The facial vein receives lateral tributaries, corresponding to the branches of 
the artery {i. e., inferior palatine, submaxillary, submental, inferior labial, infe- 
rior and superior coronary, and lateral nasal) and in addition the following : 
The inferior palpebral veins, two or three in number, descend from the lower 
eyelid, where a communication with the infra-orbital vein is established. 
The anterior internal maxillary vein or deep facial vein passes downward and 
forward from the pterygoid plexus. It crosses the zygomatic surface of the max- 
illa, and opens into the facial vein beneath the zygomaticus major muscle. 
Small buccal, masseteric, and parotid veins are received from the buccinator and 
masseter muscles and the glandula socia parotidis, respectively. 
Sometimes the lingual vein joins the facial. (See lingual vein.) 
The free communications between the facial vein and its tributaries and the 
ophthalmic vein, none of which contain valves, account for the danger of septic 
thrombi extending backward through the ophthalmic vein to the cranial sinuses 
in case of carbuncle or anthrax of the face. 
B-. LATERAL REGION. 
The Temporo-maxillary Vein (posterior facial) is formed by the union of the 
temporal and maxillary veins in the substance of the parotid gland behind the 
neck of the mandible. It descends in the substance of the parotid gland super- 
ficial to the external carotid artery to about the angle of the jaw, where it divides 
into two parts. The anterior division passes downward and forward to join the 
facial vein, forming the common facial vein, while the posterior division is joined 
by the posterior auricular vein to form the external jugular vein. 
The posterior auricular vein may join the temporo-maxillary vein before 
bifurcation of the latter, in which case the anterior division is properly a branch 
of the external jugular vein. 
The Superficial Temporal Vein collects the blood from the parietal region of 
the scalp, where communicating branches connect it with the supra-orbital and 
frontal veins in front, the veins of the opposite side above, and the posterior 
auricular and occipital veins behind. Its branches unite into two trunks which, 
corresponding to the divisions of the artery, converge and unite in front of the 
ear into a single trunk. 
The Middle Temporal Vein receives the blood from the temporal muscle, and is 
joined by the orbital branch, which, corresponding to the artery of the same name, 
communicates with the ophthalmic vein. Piercing the fascia near the zygoma it 
joins the superficial temporal to form the common temporal vein. The middle 
temporal vein communicates with the pterygoid plexus through the deep temporal 
veins, a branch of that plexus corresponding to the arteries of the same name. 
The Common Temporal Vein crosses the base of the zygoma just in front of the 
ear, and thence descends in the parotid gland external to the temporal artery. It 460 
THE BLOOD-VASCULAR SYSTEM. 
joins the internal maxillary vein opposite the neck of the jaw to form the 
temporo-maxillary vein. 
The temporal vein also receives anterior auricular veins from the external ear, 
transverse facial veins from the masseter muscie, parotid veins from the gland, and 
branches from the plexus around the temporo-maxillary articulation, which 
receives a branch from the tympanum, through the fissure of Glaser. 
The Internal Maxillary Vein is a short vessel, which passes backward from the 
pterygoid plexus, accompanying the corresponding artery as a single or a double 
trunk to join with the common temporal vein in forming the temporo-maxillary 
vein. 
The Pterygoid Plexus surrounds the pterygoid muscles and corresponds to the 
second and third portions of the internal maxillary artery, by the companion 
veins of whose branches it is made up. It communicates in front with the facial 
vein, through the deep facial vein, above with the inferior ophthalmic vein and 
the cavernous sinus, and behind with the plexus from which the middle temporal 
vein arises. 
The Posterior Auricular Vein descends from a plexus on the lateral aspect of the 
scalp, which communicates with the temporal and occipital veins and with the 
vein of the opposite side. It is large in comparison with its companion artery, 
which it leaves below the ear, and inclines forward toward the angle of the jaw 
to join the posterior division of the temporo-maxillary vein, and form the 
external jugular vein. 
The Occipital Veins collect the blood from the hind part of the venous plexus 
of the scalp, and descend, as one or two trunks, with the occipital artery deeply 
into the neck, where they are continuous with the deep cervical vein. An emis- 
sary vein, passing through the mastoid foramen, connects the lateral sinus with 
this vein) or, in some cases, with the posterior auricular vein. 
C. POSTERIOR REGION. 
2. Veins of the Neck (Fig. 493), 
The External Jugular Vein, formed by the union of the posterior auricular 
vein and the posterior division of the temporo-maxillary vein, descends nearly 
vertically from its commencement near the angle of the jaw to terminate opposite 
the middle of the clavicle in the subclavian vein. It lies beneath the platysma, 
and crossing the sterno-mastoid muscle obliquely it follows the hind border of 
the latter in its lower half. Near the clavicle it pierces and is closely connected 
with the deep cervical fascia, which holds it open. It has a pair of imperfect 
valves at its entrance into the subclavian vein, and another an inch or two above 
the clavicle, and the part between them is called the sinus, being often dilated. 
Its lateral tributaries are the following : 
The posterior external jugular vein. This descends behind the sterno-mastoid 
muscle, from the skin and superficial muscles of the upper and back part of the 
neck and the lower occipital region, to open below the middle of the external 
jugular vein. It may communicate with the occipital vein. 
The transverse cervical and suprascapular veins accompany their corresponding 
arteries, and open into the external jugular vein a little above its termination. 
They sometimes present a plexiform arrangement in the subclavian triangle. 
These veins have valves near their termination and may sometimes open into 
the subclavian vein. 
The anterior jugular vein takes origin below the chin from small branches 
which communicate with the lower radicles of the facial vein. It descends at a 
variable distance from the median line to near the inner end of the clavicle, 
where it perforates the deep fascia and turns outward beneath the sterno-mastoid 
muscle to open into the lower end of the external jugular vein, or sometimes into THE VEINS. 
461 
the subclavian vein. It receives a branch from the facial vein which descends 
along the ventral border of the sterno-mastoid muscle. A transverse branch 
connects the lower ends of the veins of the two sides, and others may exist 
higher up. 
Its position behind the origin of the sterno-mastoid should be remembered in 
tenotomy of that muscle. It varies in size inversely with that of the external 
jugular vein. 
The Internal Jugular Vein receives the blood from the cranial cavity. It 
begins at the enlarged sinus or bulb of the sigmoid sinus, which is lodged in the 
large dorsal compartment of the jugular foramen. After a nearly straight 
FACIAL- 
ANTERIOR.... 
JUGULAR^ 
INTERNAL 
MAMMARV 
Fig. 493.—Veins of the neck and upper part of thorax, front view. (Testut.) 
course it ends behind the sternal end of the clavicle, where it joins the subclavian 
vein to form the innominate vein. At the base of the skull it is behind and then 
becomes external to the internal carotid artery. Lower down it lies external to 
and in the same sheath with the common carotid artery, overlapping it below, 
especially on the left side. A pair of imperfect valves is found about an inch 
above its termination. It has the following lateral tributaries. 
The inferior petrosal sinus opens into the bulb or into the commencement of 
the internal jugular vein. 
The pharyngeal plexus, on the outer surface of the pharynx, receives the blood 
from the neighboring parts, and opens into the jugular vein directly or through 
the common facial vein. It communicates above with the pterygoid plexus and 
receives branches from the soft palate and Eustachian tube. 
The lingual vein (Fig. 494). Two small vense comites usually accompany the 
lingual artery, but most of the blood is returned from the tongue by the ranine 462 
THE BLOOD-VASCULAR SYSTEM. 
vein, which starts near the tip of the tongue, and passes backward beneath the 
mucous membrane of its under surface. As it continues backward it is separated 
from the lingual artery by the hyoglossus muscle, on the outer surface of which 
it lies below the hypoglossal nerve. It is joined by the lingual venae comites and 
by branches corresponding to the branches of the artery, and empties into the 
[AMINE 
INTERNAL 
CAROTID 
Fig. 494.—Arteries and veins of the tongue, viewed from the right side. (Testut.) 
internal jugular or the facial vein. Its tributaries not infrequently open separately 
into the internal jugular or into the facial vein. 
The common facial vein has been described above. 
The superior thyroid vein corresponds to the artery of the same name, and, 
after crossing the upper end of the common carotid artery, it empties into the 
internal jugular or the common facial vein. The three thyroid veins on each 
side communicate freely with each other and with those of the opposite side. 
The middle thyroid vein emerges from the lower part of the lateral lobe of 
the thyroid body, and, after crossing the common carotid artery, empties into the 
internal jugular vein, a little below the level of the cricoid cartilage. 
The Inferior Thyroid Veins descend from the lower part of the thyroid body, 
one on either side of the trachea. Frequent anastomoses form a kind of plexus, 
from which the left vein descends to empty into the left brachio-cephalic vein, 
the right vein into the angle of union of the two brachio-cephalic veins, or into 
the lower end of the right brachio-cephalic vein, or it may join the left vein. 
They lie under cover of the sterno-hyoid muscles, and receive inferior laryngeal, 
tracheal, and oesophageal veins. They are guarded by valves at their termination. 
They may seriously embarrass the surgeon in performing low tracheotomy. 
The Vertebral Vein corresponds to the cervical portion only of the vertebral 
artery. Commencing in the suboccipital triangle in a plexus of small veins, it 
accompanies the vertebral artery in a plexiform manner through the foramina of 
the transverse processes of the upper six cervical vertebrae. Thence as a single 
vessel it descends across the subclavian artery to open into the upper end of the 
brachio-cephalic vein, dorsally. 
Tributaries.—At its upper end it communicates with the occipital, deep 
cervical, and intraspinal veins. It receives branches from the dorsal spinal 
veins of the neck, the lateral spinal veins, and the plexus on the ventral surface of 
the bodies of the cervical vertebrae. Near its lower end it is joined by the deep 
cervical and anterior vertebral veins, and usually by the first intercostal vein, 
which accompanies the superior intercostal artery. 
The anterior vertebral vein descends from in front of the cervical vertebrae, THE VEINS. 
accompanying the ascending cervical artery, and receiving branches from the 
neighboring muscles. 
The deep cervical vein (posterior vertebral) descends at the back of the neck, 
in company with the deep cervical artery, from the suboccipital plexus, through 
which it receives the occipital vein. Below the transverse process of the seventh 
cervical vertebra it turns forward to empty into the lower end of the vertebral 
vein. 
The Veins of the Diploe (Fig. 495). 
These are contained in a plexus of bony channels in the cancellous tissue of 
the bones of the roof and sides of the skull. They are arranged in four groups, 
Fig. 495.—Veins of the dlploe. The outer table of cranial bones is removed. (Testut.) 
whose trunks descend to communicate with the meningeal veins, the sinuses of 
the dura and the veins of the scalp. They are named from their position. 
The frontal veins of the diploe open into the supra-orbital vein at the bottom 
of the supra-orbital notch or foramen. 
The anterior temporal veins open into the deep temporal veins through an 
opening in the great wing of the sphenoid. 
The posterior temporal veins join the lateral sinus through the mastoid foramen 
or an opening at the dorso-inferior angle of the parietal bone. 
The occipital veins open into the occipital vein externally, or into the lateral 
sinus internally. 
In foetal life the veins of each bone are distinct, but they anastomose freely 
after the bones come together. 
The Venous Sinuses of the Cranium (Figs. 496, 497). 
These are venous channels situated between the two layers of the dura, and 
lined by a continuation of the lining membrane of the veins. They collect the 
blood from the brain, orbit, and eyeball, and some of that from the meninges and 
diploe, and empty into the internal jugular vein. They communicate with the 
superficial veins by means of the emissary veins, passing through certain foramina 
in the cranium. They may be divided into two groups, the one situated above and 
behind, the other at the base of the skull; the former including the superior and 
inferior longitudinal, the straight, the lateral, and the occipital sinuses, while the 
latter embraces the cavernous, the circular, the basilar, and the inferior and 
superior petrosal sinuses. 
The Superior Longitudinal Sinus extends in the median line along the attached 464 
THE BLOOD-VASCULAB SYSTEM. 
margin of the falx cerebri, increasing constantly in size, from the foramen caecum 
in front to the internal occipital protuberance behind, where, turning sharply to 
one side, usually the right, it is continuous with the lateral sinus. Its triangular 
lumen is crossed by a number of fibrous bands (the cords of Willis), and pro- 
jecting into it at intervals are the Pacchionian bodies. It receives the superior 
cerebral veins, which enter it mostly from behind forward (i. e., against the blood- 
stream). It often communicates through the parietal foramen with the temporal 
veins of the scalp, and regularly in early life through the foramen caecum with 
the veins of the nose. On approaching the internal occipital protuberance it 
inclines slightly to the side to which it bends, and presents a dilatation, the torcu- 
lar Herophili (“ the wine-press of Herophilus ”), which is lodged in a depression 
on the side of the internal occipifal protuberance. The torcular usually receives 
the occipital sinus, and gives a cross-branch to the straight sinus, where the latter 
bends into the opposite lateral sinus. 
The Inferior Longitudinal Sinus is a small vessel of cylindrical form, which 
occupies the hind half or more of the lower border of the falx cerebri. It receives 
some branches from the falx and the median surface of the brain, and terminates 
in the straight sinus. 
The Straight Sinus, triangular on section, extends downward and backward 
along the line of junction of the falx cerebri and the tentorium cerebelli, to the 
internal occipital protuberance, where it bends sharply to the side, usually to the 
Fig. 496.—Sinuses of the dura, left lateral view. (Testut.) 
left, and is continued into the lateral sinus, being connected by a cross-branch 
with the torcular. It is formed in front, at the margin of the tentorium, by the 
union of the inferior longitudinal sinus with the great vein of Galen from the 
interior of the brain. 
The Lateral Sinuses commence at the internal occipital protuberance, and end at 
the jugular foramina in the bulbs or sinuses which are continuous with the internal THE VEINS. 
465 
jugular veins. Each sinus passes at first nearly horizontally outward, with a 
slight convexity upward, in the groove on the occipital bone and the dorse-infe- 
rior angle of the parietal bone, along the attachment of the tentorium cerebelli. 
Thence it curves downward and inward in the groove on the inner surface of the 
mastoid, leaving the tentorium after receiving the superior petrosal sinus (and, 
when present, the petro-squamous sinus). Finally it curves forward onto the 
jugular process of the occipital bone to the jugular foramen. That part of the 
sinus on the mastoid bone and the jugular process of the occipital is called the 
sigmoid sinus, from its S-shaped course. This part is semicylindrical in shape, 
communicates with the occipital sinus through the marginal sinus, and with the 
occipital and vertebral veins through the mastoid and posterior condylar foramina. 
The lateral sinus receives veins from the temporal lobe of the brain, from the 
upper and lower surfaces of the cerebellum, and from the medulla, pons, and 
diploe. The right lateral sinus is considerably larger than the left, except in 
cases where the superior longitudinal sinus is continued into the left sinus. 
The 'position of the lateral sinus may be represented on the exterior of the 
skull by a line curved slightly upward from the external occipital protuberance to 
CAVERNOUS I 
SINUS I 
SUPERIOR LONGITU- 
DINAL SINUS 
Fig. 497—Sinuses of the dura at the base of the cranium. (Testut.) 
the base of the mastoid process, and thence its sigmoid portion bends downward 
and inward toward the tip of the process, making a forward bend or knee which 
extends to within half an inch or less of the upper part of the bony external 
auditory meatus. 
The Occipital Sinus ascends mesially, along the line of attachment of the falx 
cerebelli to the occipital bone, from the foramen magnum in front to the torcular 
behind. Its tributaries pass around one or both sides of the foramen magnum, as 
marginal sinuses, one or both of which communicate with the lower end of the 466 
THE BLOOD-VASCULAR SYSTEM. 
lateral sinuses. It communicates with the posterior spinal veins, and receives 
inferior cerebellar veins. 
The Cavernous Sinuses (Fig. 498) lie between the layers of the dura, one on 
each side of the body of the sphenoid bone. They extend from the sphenoidal 
fissure in front, where they receive and are practically continuous with the oph- 
thalmic veins, to the apex of the petrous bone behind, where they end in the 
petrosal sinuses. The two are connected across the middle line in front, behind, 
and often below the pituitary body, by vessels which are called anterior, posterior, 
and inferior intercavernous sinuses, and which together form the circular or coronary 
sinus. Each cavernous sinus is bridged across by fibrous bands, so that its cavity 
resembles cavernous tissue, from which it derives its name. In the outer wall are 
the third, fourth, and ophthalmic divisions of the fifth nerve, which lie in the order 
named from above downward and from within outward. The internal carotid 
artery and the sixth nerve also pass along in the sinus separated from its lumen 
INTERNAL CAROTID ARTERY 
AND SIXTH NERVE 
OCULO-MOTOR 
NERVE 
TROCHLEAR. 
NERVE 
PITUITARY 
BODY 
OPHTHALMIC _ 
NERVE 
SUPRAMAXILLARY_ 
NERVE / 
SPHENOIDAL 
SINUS 
BODY OF 
SPHENOID 
Fig. 498.—Cavernous sinus, as shown by transverse section through the middle of the sella turcica. (W. 
Keiller.) 
FIBROUS TRABECUL/Z 
by its endothelial lining only. This sinus receives some inferior cerebral veins, 
and communicates with the pterygoid plexus through the ophthalmic vein, and 
through a slender vein passing through the foramen of Vesalius and another 
through the foramen ovale. It also communicates with the pharyngeal plexus 
and the internal jugular vein, by branches passing through the foramen lacerum 
medium and the carotid foramen respectively. This sinus also receives in front 
the small spheno-parietal sinus, which, communicating with the middle menin- 
geal veins, near the apex of the small wing of the sphenoid, runs inward on the 
under surface of this bony process. 
The Superior Petrosal Sinus extends backward as a narrow channel in the 
attached margin of the tentorium cerebelli, along the groove in the upper border 
of the petrous bone, from the cavernous sinus in front to the lateral sinus behind. 
It receives veins from the temporal lobe of the brain, the cerebellum, and the 
tympanum. 
The Inferior Petrosal Sinus, larger but shorter than the superior, runs back- 
ward and downward in a groove along the petro-occipital suture, from the hind 
end of the cavernous sinus in front to the upper end of the internal jugular vein, 
which it reaches after passing through the forward compartment of the jugular 
foramen. It receives inferior cerebellar veins, and veins from the medulla, pons, 
and internal ear. 
The Transverse or Basilar Sinus (basilar plexus). Connecting the two inferior 
petrosal sinuses across the median line is a plexus of veins, lying in the dura on 
the basilar process of the occipital bone. It communicates below with the ante- 
rior spinal veins. 
The petrosquamous sinus is sometimes found in the adult in a groove along 
the petro-squamous suture, opening behind into the lateral sinus, where the latter 
bends downward onto the mastoid bone. It represents the remains of an early 
foetal condition, in which the lateral sinuses are continued forward in this course 
to open into the primitive (afterwards the external) jugular vein, before the 
development of the internal jugular vein. 467 
THE VEINS: 
The Ophthalmic Veins. 
Commencing near the inner canthus of the eyelid, where it communicates 
freely with the angular, frontal, and supra-orbital veins, the principal or Supe- 
rior Ophthalmic Vein extends backward and inward to the inner end of the sphe- 
noidal fissure, through which it passes to end in the fore part of the cavernous 
sinus. In the orbit it crosses above the optic nerve, a little in front of the artery, 
and receives branches similar to those of the artery. 
The Inferior Ophthalmic Vein.—Formed by the union of some inferior mus- 
cular branches with the lower posterior ciliary branches, this smaller ophthalmic 
vein runs backward in the floor of the orbit, beneath the optic nerve. It ter- 
minates by joining the superior ophthalmic vein to form the short common ophthal- 
mic trunk, or by opening separately into the cavernous sinus. A branch, and 
occasionally the entire vein, descends through the spheno-maxillary fissure to 
join the pterygoid plexus. 
As the ophthalmic veins have no valves, the blood, under certain conditions, 
may flow from behind forward into the angular vein or its branches, and thus 
obviate pressure in the veins of the retina, when the cavernous sinus is obstructed. 
These pass through foramina in the skull to connect the cranial sinuses with 
the surface veins of the scalp. The blood-current may be in one or the other 
direction under varying conditions of intracranial pressure. They may serve as 
the channels along which infection is carried from the surface to the interior of 
the cranium. The following communications occur through emissary veins. (A) 
The longitudinal sinus communicates with the temporal veins through one or both 
parietal foramina when present, and, in the child, with the veins of the nose 
through the foramen caecum. (/>) The lateral sinus is connected with the 
occipital (or posterior auricular) vein through the mastoid foramen (the largest 
and most constant emissary), and sometimes with the vertebral vein through the 
posterior condylar foramen. (C) The cavernous sinus communicates with the 
pterygoid plexus through the foramen of Vesalius and the foramen ovale, as well 
as through the inferior ophthalmic vein ; with the pharyngeal plexus through the 
foramen lacernm medium ; and with the internal jugular vein by the carotid 
plexus through the carotid canal. (D) The occipital sinus communicates with 
the vertebral and extraspinal veins through the anterior condylar foramen. (JE) 
A small vein occasionally passes to the torcular through a foramen in the occipital 
bone, near the external occipital protuberance. 
The Emissary Veins. 
The Veins of the Brain. 
These open into the cranial sinuses and have several peculiarities. 
The Veins of the Cerebrum. 
These have very thin walls from the absence of muscular tissue, and contain 
no valves. They are more numerous than the arteries, and, for the most part, 
do not accompany them. Those veins opening into the superior longitudinal 
sinus enter it against its current, after ascending with the arteries, instead of 
descending with the ascending arteries. 
The cerebral veins may be divided, like the arteries, into a superficial set on 
the surface, which anastomose freely together, and a deep set, which emerge from 
the ventricles by the transverse fissure. 
The Superficial Veins run in the fissures, and occasionally across the gyri, and 
are subdivided into superior and inferior groups. 
The Superior Cerebral Veins, eight to twelve in number on each side, pass 
inward and slightly forward from the upper surface of the cerebrum. After 468 
THE BLOOD-VASCULAR SYSTEM. 
joining others from the mesial surface, they open into the longitudinal sinus, 
running for some distance in its walls. 
The inferior cerebral veins collect the blood from the outer and under surfaces 
of the cerebrum, and open into the cavernous, superior petrosal, or lateral sinuses, 
according to their position. The Middle Cerebral Vein is one of large size, which 
overlies the fissure of Sylvius, receiving branches from adjoining lobes, and ends 
in the cavernous sinus. The Great Anastomotic Vein of Trolard, by anastomosing 
on the parietal lobe with a branch of the middle cerebral vein and with one of 
the superior veins, establishes a communication between the cavernous and the 
superior longitudinal sinuses. Similarly the Posterior Anastomotic Vein of Lubbe 
connects the cavernous and lateral sinuses, by anastomosing with the middle 
cerebral vein on the temporal lobe. 
The Deep Cerebral Veins join to form two trunks, the Veins of Galen, which, 
beginning near the foramen of Monro by the union of the choroid vein and the 
vein of the corpus striatum on each side, pass back, parallel with and near each 
other, between the layers of the velum interpositum. Beneath the splenium of 
the corpus callosum they pass out. of the brain at the great transverse fissure, 
after joining to form a single trunk (vena magna Galeni), which ascends to enter 
the straight sinus. 
The choroid vein runs forward and upward along the outer border of the 
choroid plexus (the blood of which it returns) to its fore part where, near the 
foramen of Monro, it joins the vein of the corpus striatum. The latter runs for- 
ward in the groove between the corpus striatum and the optic thalamus, receiving 
branches from them and the neighboring parts. It joins the choroid vein as 
above described. 
Each vein of Galen, just before it joins its fellow, receives the basilar vein of 
each side which, formed by the union of the anterior cerebral vein, the deep 
Sylvian vein, and the inferior striate vein, passes backward and around the crus 
cerebri to its termination. The anterior cerebral vein runs from the genu of the 
corpus callosum, the deep Sylvian veins from the insula and adjacent parts (com- 
municating with the middle cerebral vein), and the inferior striate vein descends 
through the anterior perforated space from the corpus striatum. 
The Veins of the Cerebellum. 
These are divided into two sets, superior and inferior, according to their posi- 
tion. Of the superior cerebellar veins some run inward and upward to the straight 
sinus and the great vein of Galen, others run outward to the superior petrosal 
and lateral sinuses. The inferior cerebellar veins are larger than the superior, and 
some of them together with the veins of the oblongata and pons, run outward and 
forward to the inferior petrosal and lateral sinuses, while others pass backward 
to the occipital sinus. 
THE VEINS OF THE UPPER EXTREMITY 
Two sets of veins are distinguished in the extremities, superficial and deep, 
the latter of which accompany the arteries, while the superficial set are larger, 
return more of the blood, and lie between the layers of the superficial fascia. 
The two sets communicate at frequent intervals. Valves are numerous in both 
sets, but more so in the deep veins, and are regularly found where a branch joins 
a trunk, or the deep veins join the superficial. 
The Superficial Veins of the Upper Extremity (Figs. 499, 500) 
These commence in two plexuses, viz., a large plexus on the dorsum of the 
hand, which receives the digital veins from the fingers, and is sometimes sub- 
divided into two parts, a radial and an ulnar; and a smaller plexus on the front THE VEINS. 
469 
of the ivrist, which receives a few branches from the palm and the thumb, 
superficial veins of the forearm communicate freely with one another. 
The Radial Vein, commenc- 
ing in the radial side of the dorsal 
plexus runs up the radial side 
of the forearm to a little above 
the bend of the elbow, where, 
on the outer side of the biceps- 
tendon, it joins the median 
cephalic vein to form the ce- 
phalic vein. On the hand it 
communicates with the deep 
veins of the palmar arch, and 
along its course it receives 
many superficial tributaries. 
The Posterior Ulnar Vein 
begins in the ulnar side of the 
dorsal plexus, and, after com- 
municating with the deep pal- 
mar veins, it extends upward 
along the dorsal aspect of the 
ulnar side of the forearm. Near 
the bend of the elbow it usually 
receives the anterior ulnar vein, 
and, just below the internal 
condyle of the humerus, the re- 
sulting common ulnar vein turns 
forward to join the median 
basilic to form the basilic vein. 
CEPHALIC 
■BASILIC 
MEDIAN 
CEPHALIC'** 
MEDIAN BASILIC* 
—ULNAR 
BRANCH FROM 
—* DEEP SET 
RADIAL 
MEDIAN 
...ANTERIOR 
ULNAR 
The Anterior Ulnar Vein is 
smaller than the foregoing, 
which it joins near the bend 
of the elbow, except rarely when 
it enters the median basilic vein 
separately. It ascends from the 
wrist along the ulnar side of 
the front of the forearm. 
Fig. 499.—Superficial veins of front of forearm and lower part 
of arm. (Testut.) 
The Median Vein ascends along the front of the forearm from the plexus on 
the front of the wrist to the bend of the elbow, where, after receiving the deep 
median vein from the deep set of veins, it immediately bifurcates into the median 
basilic and the median cephalic veins. 
The Median Basilic Vein, the larger of the two divisions, is directed upward 
and inward to the groove internal to the biceps, where it forms the basilic vein by 
joining the common ulnar trunk or one of the ulnar veins. It crosses the brachial 
artery, from which it is separated by the fascial tendon of insertion of the biceps ; 
hence in venesection, in which this vein was the one commonly chosen, on account 
of its size, constancy, and accessibility, the artery was sometimes punctured, lead- 
ing to arterio-venous aneurism, etc. Branches of the internal cutaneous nerve 
cross in front of and behind it. 
The Median Cephalic Vein runs upward and outward in the groove between 
the biceps and brachio-radialis muscles to form the cephalic vein, by uniting with 
the radial vein just above the bend of the elbow. The musculo-cutaneous nerve 
passes beneath it. 
The Basilic Vein ascends in the groove, on the inner side of the biceps, a little 
internal to the course of the brachial artery. Perforating the deep fascia below 
the middle of the arm, it ends by joining the inner vena comes of the brachial 
artery to form the axillary vein. 470 
THE BLOOD-VASCULAR SYSTEM. 
The Cephalic Vein, the smaller of the veins of the arm, ascends in the groove 
external to the biceps and then in the interval between the deltoid and pectoralis 
major muscles to a little below the clavicle, where it perforates the costo-coracoid 
SUBCLAVIAN 
VEIN 
CEPHALIC VEIN 
ENTERING 
AXILLARY 
AXILLARY 
f BASILIC VEIN 
< PERFORATING 
( DEEP FASCIA 
CEPHALIC 
VEIN 
.BASILIC VEIN 
Fig. 500.—Superficial veins of front of arm and shoulder. (Testut.) 
membrane, and ends in the axillary vein, after crossing the first portion of the 
axillary artery. Sometimes a branch, and rarely the entire vein, crosses over the 
clavicle to end in the external jngnlar vein. 
The Deep Veins of the Upper Extremity. 
The arteries below the axillary are accompanied by two vence comites (“ com- 
panion veins ”) with frequent cross-branches. They communicate with the super- 
ficial veins, especially in the hand and at the elbow, Near the lower border of 
the teres major or the subscapularis muscle, the inner brachial vena comes joins 
the basilic vein to form the single Axillary Vein. This accompanies and has the 
same relations as the axillary artery, lying to its inner side, and ends at the outer 
border of the first rib in the subclavian vein. It collects all the blood of the 
upper extremity, receiving the cephalic vein and the radicles which correspond to 
the branches of the axillary artery. 
The Subclavian Vein continues the axillary vein from the outer border of the 
first rib to the sterno-clavicular articulation, where it ends in the brachio-cephalic 
vein. It lies in front of and at a somewhat lower level than the subclavian 
artery, from which it is separated by the scalenus anterior muscle and the phrenic 
nerve. It lies in the groove on the first rib in front of that of the artery. Close to 
the outer border of the sterno-mastoid muscle the external jugular vein empties 
into it, and just external to this point the vein is provided with a pair of valves. 
The Veins of the Thoracic Wall. 
The Internal Mammary Veins accompany each internal mammary artery and 
its branches in anastomosing pairs, which unite into a single trunk a short distance 
below their termination in the lower part of the brachio-cephalic vein. THE VEINS. 
471 
The Superior Intercostal Veins.—The veins from the two to four intercostal 
spaces below the first join together to form a short trunk, which on the right side 
descends to empty into the upper part of the great azygos vein, and on the left 
side ascends across the arch of the aorta to empty into the left brachio-cephalic 
vein. The left superior intercostal vein communicates interiorly with the left 
upjier azygos vein, and sometimes receives the left bronchial vein. It is often 
connected with the oblique vein of Marshall by a fibrous cord, traceable through the 
vestigial fold of the pericardium and representing the left duct of Cuvier. The 
veins of the upper intercostal space, or sometimes the upper two intercostal spaces, 
ascend to join the vertebral or brachio-cephalic vein of the corresponding side. 
The Azygos Veins (Fig. 501). 
The Azygos Veins, developed from the primitive cardinal veins, form an 
anastomosis between the inferior and superior venae cavse, which is of importance 
in obstruction of the inferior vena cava. They receive the venous blood of most 
of the dorsal and late- 
ral thoracic walls. The 
azygos veins are three in 
number, and lie on the 
sides of the front of the 
vertebral bodies. 
UPPER END OF 
‘THORACIC DUCT 
The Right or Great 
Azygos Vein (vena azygos 
major) commences in the 
abdomen as an upward 
continuation of the ascend- 
ing lumbar vein, which 
communicates with the 
common iliac vein, and 
is often connected with 
the inferior vena cava and 
the renal vein. It ascends 
through the aortic opening 
of the diaphragm on the 
right of the aorta and the 
thoracic duct, in which 
position it continues up- 
ward in the posterior 
mediastinum in front of 
the right intercostal ar- 
teries, grooving the dorsal 
border of the right pleura. 
Opposite the lower end 
of the fourth thoracic 
vertebra it bends forward 
over the root of the right 
lung, to empty into the 
superior vena cava at a 
point just above where 
the latter pierces the peri- 
cardium. 
ascending lumbafT 
Tributaries.—lt re- 
cieves (1) the right sub- 
costal vein; (2) the seven or eight lower right intercostal veins; (3) the right 
superior intercostal vein ; (4) the right bronchial veins ; (5, 6) the left lower and 
the left upper azygos veins, and some small (7) oesophageal ; (8) pericardial ; 
and (9) mediastinal veins. 
Fig. 501.—Azygos and intercostal veins. (Testut.) 472 
THE BLOOD- VASCULAR SYSTEM. 
The Left Lower or Small Azygos Vein (vena hemiazygos, vena azygos minor) 
commences in the abdomen on the left side, in a manner similar to the great 
azygos on the right side, the branch from the renal vein being more constant, 
and sometimes the principal source. It ascends through the left crus of the dia- 
phragm, and in the posterior mediastinum it lies in front of the left intercostal 
arteries as far as the eighth thoracic vertebra, where it crosses beneath the thoracic 
aorta and thoracic duct to join the great azygos vein. 
Tributaries.—It receives (1) the left subcostal vein below the diaphragm; 
and above it (2) the lower four left intercostal veins; (3) the left upper azygos 
(sometimes); and some small (4) oesophageal; and (5) mediastinal veins. 
The Left Upper Azygos Vein (vena hemiazygos accessoria) varies in size with 
that of the left superior intercostal and the left lower azygos veins, between 
which it is placed, receiving two or three intercostal veins. It connects above with 
the superior intercostal vein, and opens below into the left lower azygos vein, or, 
crossing the sixth or seventh thoracic vertebra, ends in the great azygos vein. 
It often receives the left bronchial vein. It is quite variable and often absent, 
when its radicles, the fifth, sixth, and seventh intercostal veins, open directly into 
the great azygos vein. 
The Intercostal Veins accompany the arteries as a single trunk, lying above 
thorn. They receive large dorsal branches from the muscles of the back, the 
dorsal spinal plexus, and the spinal canal. They are eleven in number, one for 
each intercostal space, the lowest thoracic vein being called the subcostal vein, 
from its position. They terminate variously in different subjects and on the two 
sides. (See azygos, superior intercostal, and vertebral veins.) 
The Bronchial Veins accompany the bronchial arteries, only part of whose blood 
they return, that distributed to the smaller bronchi entering the pulmonary veins. 
They pass out at the back of the root of the lung, and enter the upper end of the 
vena azygos major on the right side, and the left upper azygos or the left superior 
intercostal vein on the left side. 
Veins of the Spine (Figs. 502, 503). 
These form complicated plexuses, situated without and within the spinal canal 
and on the spinal cord, which communicate with one another and with the veins 
of the neck and trunk. They contain no valves and may be described in groups 
as follows : 
I. Extra-spinal Veins.—The Dorsal Spinal Veins form a plexus over the 
laminae and adjacent processes of the vertebrae, where they receive tributaries 
from the skin and muscles of the back, the larger of which run forward along 
the interspinous ligaments. They communicate with the posterior longitudinal 
spinal veins by branches perforating the ligamenta subflava, and open laterally 
into the vertebral or the dorsal branches of the intercostal and lumbar veins, 
according to the region, by branches passing forward between the transverse 
processes. 
11. The Veins of the Vertebral Bodies (vence basis vertebrarum) occupy hori- 
zontal bony channels in the vertebral bodies and communicate with the veins in 
front of and at the sides of them. They open behind, through the large single 
or double foramen on the dorsal surface of the bodies of the vertebrae, into the 
transverse connecting branches of the anterior longitudinal spinal veins. 
111. Intra-spinal Veins.—(A) The Meningo-rachidian Veins are those within 
the spinal canal between the dura and the walls of the canal. 
The Anterior Longitudinal Spinal Veins, large and plexiform, extend the 
entire length of the spinal canal behind the bodies of the vertebrae, one on either 
side of the posterior common ligament. Opposite the bodies of the vertebrae 
they are dilated and communicate with each other by transverse trunks, placed 
between the posterior common ligament and the body of each vertebra, which 
receive the veins of the vertebral bodies. Opposite the intervertebral discs they THE VEINS. 
473 
are constricted, and send lateral branches through the intervertebral foramina to 
join the vertebral, intercostal, lumbar, or sacral veins according to the region. 
They communicate with the basilar plexus above, and with the posterior spinal 
veins throughout the spinal canal. Together with the posterior spinal veins 
and the marginal part of the occipital sinus they form a venous ring around the 
foramen magnum. 
The Posterior Longitudinal Spinal Veins, smaller than the foregoing, are 
situated one on each side at the back of the spinal canal, and extend throughout 
Fig. 502.—Veins of the spine, seen in a transverse horizontal section of a thoracic vertebra. (Testut.) 
its entire length. They communicate with one another, by frequent transverse 
branches in front of the vertebral arches, with the dorsal spinal veins through the 
ligamenta snbflava, with the anterior spinal veins by lateral branches, and above 
with the occipital sinus. Lateral branches also pass out through the interverte- 
bral foramina to join those from the anterior spinal veins. 
Fig. 503.—Veins of the spine, seen in a sagittal section of two thoracic vertebrae. (Testut.) 
(B) The Veins of the Spinal Cord, of small size, run tortuously in the pia of 
the cord, and are disposed in longitudinal trunks over the median fissures and 
laterally, with plexiform communications between. Branches accompany the 
nerve-roots to the intervertebral foramina, where they join the lateral branches 
from the veins of the spinal canal. Above they join the veins of the pons and 
cerebellum. 
The principal blood-current through the veins of the spine is probably in a 
horizontal direction in the venous rings, formed by the communications between 474 
THE BEOOD- VASGULAIt SYSTEM. 
the anterior and posterior veins, which send lateral branches through the inter- 
vertebral foramina. 
THE INFERIOR VENA CAVA AND ITS TRIBUTARIES. 
The Veins of the Abdomen (Fig. 504). 
The Inferior or Ascending Vena Cava returns to the heart the blood from 
the lower extremities, the pelvis, and the abdomen, except that returned by the 
azygos and superior epigastric veins. It is a large vessel, which is formed by 
the union of the two common iliac veins in front of the right upper segment of 
—PHRENIC 
•CCELI AC 
-RENAL 
SPERMATIC 
A LUMBAR VEIN- 
INFERIOR 
"MESENTERIC 
Fig. 504.—Inferior vena cava and its tributaries. 
the fifth lumbar vertebra. Thence it runs upward to the right of the aorta, from 
which it is separated above by the right crus of the diaphragm and the lobus 
Spigelii of the liver as it inclines forward and lies in the groove or canal on the 
dorsal surface of the liver. On passing through the caval opening in the central 
tendon of the diaphragm, to the margins of which it is attached, it immediately THE VEINS. 
475 
enters the pericardium, through which it passes for about half an inch, only partly 
invested by its serous layer, to open into the lower and back part of the right 
auricle, opposite the upper border of the ninth thoracic vertebra. In the abdomen 
the liver, pancreas, duodenum, mesentery, portal vein, and right spermatic (or 
ovarian) artery, lie in front of it; the vertebrae, right renal and lumbar arteries, 
and the right crus of the diaphragm, behind it. 
Tributaries.—The hepatic veins converge from the substance of the liver to the 
groove or canal occupied by the inferior vena cava, into which they empty in two 
or three trunks. The veins from the right and left lobes open so obliquely that 
the semilunar folds, presented at the lower border of their orifices, take the place 
of valves, which are otherwise wanting. These veins are of large size, and 
return the blood of the hepatic artery and the portal vein. 
The phrenic (or inferior phrenic) veins accompany the phrenic arteries. The 
right one opens directly into the vena cava just below the diaphragm, on the right 
side, while the left often joins the left suprarenal, or sometimes the left renal 
vein. 
The suprarenal veins.—One vein on each side returns all the blood supplied 
by the three suprarenal arteries. The right vein terminates in the vena cava, the 
left in the left renal or phrenic vein. 
The renal veins are large, short trunks, which run in front of the correspond- 
ing arteries from the hilum of the kidney to the vena cava, into which they 
empty nearly at right angles, the left a little above the right. The left renal 
vein is larger than the right, has to cross the aorta, which it does just below the 
origin of the superior mesenteric artery, after receiving the spermatic (or ovarian) 
vein, often the suprarenal vein, and sometimes the phrenic vein of the same side. 
Rudimentary valves are found, especially on the left side. The shortness of the 
right renal vein should be remembered when dealing with the pedicle in nephrec- 
tomy. 
The spermatic veins (Fig. 505) return the blood from the testicle and epi- 
didymis, from which they emerge dorsally, and, ascending to and through the 
inguinal canal, form a thick plexus (pampiniform (“ tendril-shaped ”) plexus) in 
front of the vas deferens and the spermatic artery. On entering the abdomen 
through the internal abdominal ring the plexus merges into two or three veins, 
which accompany the spermatic artery beneath the peritoneum, on the psoas mus- 
cle and across the ureter. In their course they join to form a single trunk, which 
opens into the vena cava on the right side, and on the left side into the renal 
vein, which it meets at a right angle. Imperfect valves are found in the pam- 
piniform plexuses, but the valve described at the termination of the vein may be 
absent in the vein of the left side, which moreover is usually slightly longer than 
the right vein and passes beneath the sigmoid colon, where it may be subjected 
to pressure. 
The above differences combined are held to account for the greater frequency 
of varicocele on the left side. A few small veins ascend from the testicle behind 
the spermatic artery and the vas deferens and join the epigastric veins above. 
They are commonly not ligated in the operation for varicocele. 
The ovarian veins are analogous to the spermatic veins and terminate in the 
same manner. The ovarian or pampiniform plexus, in which they begin, lies near 
the ovary between the layers of the broad ligament, and communicates freely with 
the uterine plexus, as well as with the ovarian bulb, a plexus of fine veins at the 
hilum of the ovary. They follow the course of the ovarian arteries. 
The lumbar veins, usually four in number on each side, accompany the lumbar 
arteries. They are formed by the union of ventral branches from the abdominal 
walls, where they communicate with the epigastric and internal mammary veins, 
and dorsal branches, which receive tributaries from the muscles of the back and 
the veins of the spine. The lumbar veins pass forward upon the bodies of the 
vertebrae beneath the psoas muscle, and on the left side beneath the aorta, to 
empty into the back of the vena cava. In front of the transverse processes and 476 
THE BLOOD-VASCULAR SYSTEM. 
behind the psoas muscle the lumbar veins of each side are connected by con- 
tinuous vertical branches, called the ascending lumbar vein, which communicates 
below with the ilio-lumbar, common iliac, and lateral sacral veins, and is usually 
continued above as the azygos vein of the corresponding side. 
Fig. 505.—Spermatic veins. (Testate 
The Common Iliac Veins. 
The Common Iliac Veins, formed opposite the sacro-iliac articulations by the 
confluence of the internal and the external iliac veins, converge as they ascend, 
and unite opposite the right upper segment of the fifth lumbar vertebra to form 
the inferior vena cava. The 7'ight vein, shorter and more vertical than the left, 
lies behind and internal to its artery below, but above crosses obliquely behind it 
to its outer or right side, where it is joined by the left vein. The latter lies internal 
to the left common iliac artery and then crosses behind the upper end of the right 
artery to join the right vein. They contain no valves, except an occasional one 
in the left vein. 
Tributaries.—The ilio-lumbar veins follow the ilio-lumbar arteries, and enter 
the common or internal iliac veins. They resemble the lumbar veins in their 
course, formation, and connections. The middle sacral veins, one on each side of 
the artery of the same name, ascend on the front of the sacrum to open into the 
left common iliac vein, after uniting into a single trunk. Occasionally this trunk 
enters the angle of junction of the two common iliac veins. These veins anasto- 
mose with the lateral sacral and the hemorrhoidal veins. 477 
THE VEINS. 
The External Iliac Vein (Fig. 506). 
This is the continuation of the femoral vein, and extends from the level of the 
inguinal (Poupart’s) ligament to the sacro-iliac articulation, where it joins the 
internal iliac vein. While it is internal to the artery on both sides below, on the 
ILIO- 
LUMBAR 
LATERAL 
" SACRAL 
CIRCUMFLEX J 
[-GLUTEAL 
SUPERIOR VESICAL.* 
EPIGASTRIC” 
OBTURATOR., 
INFERIOR VESICAL 
SCIATIC 
INTERNAL PUDIC 
■•MIDDLE SACRAL 
INTERNAL PUDIC*5 
Fig. 506.—External iliac vein of right side. (Testut.) 
right side above it inclines behind it. It contains one or two valves, and just 
above the inguinal ligament it receives the deep epigastric and the deep circumflex 
iliac veins, which accompany the corresponding arteries. A pubic vein, cor- 
responding to the pubic branch of the obturator artery, ascends from the obturator 
vein to join the external iliac vein, and sometimes forms the main outlet of the 
obturator vein. 
The Portal System of Veins (Fig. 507) 
These are distinguished from other veins by beginning and ending in capil- 
laries. The portal vein collects the blood from the chylopoietic viscera (the stomach, 
intestines, and pancreas), as well as from the spleen and the gall-bladder, and 
conveys it to the liver, to the capillaries of which it is distributed to be collected, 
together with the blood from the hepatic artery, by the hepatic veins, and so 
carried to the vena cava. The veins of this system have no valves. 
The Portal Vein (vena portce) (Fig. 508) is formed by the union of the splenic 
and the superior mesenteric veins, behind the upper end of the head of the 
pancreas, in front of the vena cava, and opposite the right side of the body 
of the first lumbar vertebra. From this point it runs upward and somewhat 
to the right for about three inches, to near the right end of the transverse fissure 
of the liver. Here it is somewhat enlarged (sinus of the portal vein), and divides 
into right and left branches, which enter their respective lobes and divide into 478 
THE BLOOD-VASCULAB SYSTEM. 
branches, in company with the hepatic artery and the hepatic duct. In its 
upward course it passes behind the first part of the duodenum, and then between 
the two layers of the right border of the small omentum, where it lies behind 
and between the hepatic artery on the left, and the common bile-duct on the right, 
and in front of the foramen of Winslow. These three structures, with the 
accompanying nerves and lymphatics, are enclosed by a connective-tissue sheath 
SPLENIC 
HEMOR- 
RHOIDAU 
Fig. 507.—Portal system of veins. The liver is turned upward and backward, and the transverse colon 
and most of the small intestines are removed. (Testut.) 
called the capsule of Glisson. The left branch is longer and smaller than the right, 
and where it crosses the umbilical fissure it is joined in front by the round 
ligament, the remains of the foetal umbilical vein, and behind by another fibrous 
cord, the remains of the ductus venosus. 
Tributaries.—Besides the superior mesenteric and the splenic veins, which by 
their union form the portal vein, the latter receives the pyloric and coronary 
veins from the stomach, and sometimes the cystic vein, which usually runs into 
the right branch. THE VEINS. 
479 
The Superior Mesenteric Vein accompanies the corresponding artery, lying to 
the right and in front of* it, and returns the blood from the parts supplied by it 
(the small intestine, caecum, ascending and transverse colon) by branches cor- 
responding to those of the artery. It passes upward between the layers of the 
mesentery, and then in front of the third part of the duodenum and behind the 
pancreas, where, after receiving the right gastro-epiploic vein, it joins the splenic 
vein to form the portal vein. 
The Inferior Mesenteric Vein returns the blood from the rest of the large 
intestine (rectum, sigmoid flexure, and descending colon). Commencing in the 
hemorrhoidal plexus of the lower end of the rectum, where it freely anastomoses 
VERTEBRA 
SUPRARENAL CAPSULE 
SUPRARENAL CAPSULE 
GREAT CAVITY OF 
PERITONEUM 
COM MON 
BILE DUCT 
HEPATIC 
ARTERY 
Fig. 508.—Transverse horizontal section through the foramen of Winslow, showing the relations of the 
portal vein. (Testut.) 
with branches of the internal iliac vein, it passes up and out of the pelvis to the 
left of the inferior mesenteric artery. Above the origin of the latter it ascends, behind 
the peritoneum on the left side of the aorta, to the deep surface of the pancreas, 
where, inclining to the right, it joins the splenic vein near its termination. 
The Splenic Vein is a vessel of large size, which passes from left to right below 
its companion artery, behind the pancreas. It commences by the union of several 
large branches from the hilum of the spleen, and ends, after crossing in front of 
the aorta, by joining the superior mesenteric vein, nearly at a right angle, to form 
the portal vein. It receives branches corresponding to those of the artery, and, in 
addition, the inferior mesenteric vein. 
The Pyloric Vein is a small vessel which runs along the small curvature of 
the stomach from left to right in company with the (superior) pyloric artery. It 
opens into the lower part of the vena portae. 
The Coronary or Gastric Vein is a larger vessel, which accompanies the artery 
of the same name along the small curvature of the stomach from right to left. 
Near the cardiac orifice of the stomach it receives oesophageal branches and turns 
to the right across the spine, to end in the portal vein a little above the foregoing. 
The Veins of the Pelvis. 
The Internal Iliac Veins are short trunks without valves, which lie behind and 
to the inner side of the internal iliac arteries. They extend from the upper part 
of the great sacro-sciatic foramina to the sacro-iliac articulations, where they join 
the external iliac to form the common iliac veins. Each is formed by the union 
of veins corresponding to the branches of the internal iliac artery, excepting the 
ilio-lumbar vein, which opens into the common iliac vein, and the foetal umbilical 
veins, which connect with the left branch of the portal vein. 
The Tributaries correspond to the branches of the artery, except that the pudic 
vein does not begin in the dorsal vein of the penis, but in the veins of the corpus 
cavernosum. 
The visceral veins are characterized by their large size, the number of their 
valves, and their frequent anastomoses, by which several connected plexuses are 
formed—i. e., prostatic, vesical, vaginal, uterine, and hemorrhoidal. 480 
THE BLOOD-VASCULAR SYSTEM. 
The Lateral Sacral Veins.—These parietal tributaries also form a plexus, the 
sacral plexus, over the front of the sacrum, by anastomoses with one another and 
with the middle sacral veins. This plexus communicates with the veins of the 
spine through the anterior sacral foramina. 
The Dorsal Vein of the Penis (Fig. f509), beginning in a plexiform circle of 
veins around the corona glandis, passes backward in the median dorsal groove of 
the penis, between the two dorsal 
arteries. At the root of the penis 
it continues backward through the 
suspensory ligament, and then 
through the triangular ligament, 
whereupon it divides into two lateral 
branches, which enter the prostatic 
plexus. It receives branches from 
the substance and surface of the 
penis. In front of the triangular 
ligament it communicates with the 
internal pudic veins. The dorsal 
vein may commence as two lateral 
branches in front, which unite at a 
variable distance from the root of 
the penis. 
The Gluteal, Sciatic, Obturator, 
and Internal Pudic Veins, save for 
the exception above noted in the 
case of the internal pudic vein, 
correspond with the arteries and 
arterial branches which they ac- 
company. 
The Prostatic Plexus surrounds 
the prostate, especially at its base, 
sides, and in front, and lies beneath 
the sheath derived from the recto- 
vesical fascia. Besides the veins of 
the prostate it receives the dorsal 
vein of the penis in front, and com- 
municates with the vesical and hemorrhoidal plexuses. It is frequently much 
enlarged and varicose in old men, and often contains phleboliths or vein stones. 
The Vesical Plexus surrounds the bladder beneath its peritoneal coat. It is 
particularly developed at the base and neck of the organ, where it communicates 
with the hemorrhoidal plexus, and with the prostatic plexus in the male, the 
vaginal plexus in the female. The prostatic and vesical plexuses open into the 
internal iliac veins by vessels passing from their lateral aspect. An abundant 
plexus of veins is often met with on the anterior surface of the bladder on open- 
ing that, organ by the suprapubic incision. 
The Vaginal Plexus surrounds the lower part of the vagina, and communicates 
with the vesical and hemorrhoidal plexuses and with the veins of the uterus. 
The Uterine Plexus empties in part through the ovarian veins, and in part 
through the veins which accompany the uterine arteries. It is much enlarged 
during pregnancy. 
The Hemorrhoidal Plexus lies beneath the raucous membrane of the lower part 
of the rectum. It communicates with the plexuses in front of it, and empties 
through the superior, middle and inferior hemorrhoidal veins, which accompany 
the arteries of the same name. 
•SUPERFICIAL DORSAL VEIN 
EXTERNAL PUDIC VEIN 
■ OBTURATOR VEIN 
OS PUBIS 
Fig. 509,—Veins of the penis. (Testut.) 
As the superior hemorrhoidal vein is a tributary of the portal system 
through the inferior mesenteric vein, and the other hemorrhoidal veins enter 
the internal iliac vein, a free anastomosis is thus established between the two THE VEINS. 
481 
through this plexus. The veins of this plexus have no valves; hence the fre- 
quency of hemorrhoids from obstruction of the portal circulation in the liver. 
VEINS OF THE LOWER EXTREMITY. 
These, like the veins of the upper extremity, are divided into two sets, super- 
ficial and deep. 
Superficial Veins of the Lower Extremity (Figs. 510-512). 
These consist of two main trunks, internal and external, which commence 
in an arched plexus over the instep and on the dorsum of the foot, called the 
dorsal plexus. 
The Dorsal Plexus receives the dorsal digital veins 
and branches from the small but numerous plexiform 
veins of the sole, which pass up behind the clefts of 
the toes and around the outer and inner borders of 
the foot. The veins are provided with numerous 
valves. 
The Internal or Long Saphenous Vein commences 
at the inner part of the dorsal plexus, where it re- 
ceives a vein of large size from the inner side of the 
great toe, and ends in the femoral vein an inch and 
a half below the inguinal ligament, after perforating 
the fascia lata of the saphenous opening. In its 
course it ascends in front of the internal malleolus, 
along the inner side of the leg, with the internal 
saphenous nerve, then behind the internal condyle of 
the femur, and finally upward and somewhat out- 
ward on the inner and forepart of the thigh. It is 
joined by various superficial tributaries along its 
course, by communicating branches from the deep 
veins of the sole, leg, and thigh, and, just below its 
termination, by the superficial circumflex iliac, super- 
ficial epigastric, and external pudic veins, which ac- 
company the arteries of the same name, and also in 
many cases by a large anterior branch, which ascends 
over the front of the thigh. This vein contains from 
seven to twenty valves, more numerous in the thigh 
than in the leg. 
The External or Short Saphenous Vein, com- 
mencing at the outer part of the dorsal plexus, 
ascends behind the external malleolus and then on 
the outer and back part of the leg, with the external 
saphenous nerve, to the lower part of the popliteal 
space, where it perforates the deep fascia, and ends in 
the popliteal vein. 
Along its course it is joined by superficial 
branches from the foot, the heel, and the back of 
the leg, and communicates with the deep veins at the 
ankle and in the leg. Near its termination a com- 
municating branch usually runs upward and forward 
to the internal saphenous vein, and sometimes forms 
the main outlet of the external saphenous vein. This 
vein contains from nine to fourteen valves. 
Fig. 510.—Superficial veins of 
the front of the leg and foot. (Tes- 
tut.) 482 
THE BLOOD- VASCULAR SYSTEM. 
Deep Veins of the Lower Extremity. 
Below the knee the deep veins accompany the respective arteries in pairs, 
as venae comites. 
The single Popliteal Vein is formed by the junction of the venae comites of the 
anterior and posterior tibial arteries, near the lower border of the popliteus 
Fig. 511.—Superficial veins of the dorsum 
of the leg. (Testut.) 
Fig. 512.—Superficial veins of the front of the right 
thigh. (Testut.) 
muscle. This vein lies superficial to its artery throughout, internal to it below, and 
external to it above, after crossing it obliquely. It receives radicles correspond- 
ing to the branches of the artery, and in addition the external saphenous vein. 
Two or three valves are usually present. After passing with its artery through 
the opening in the adductor magnus, it is continued as the Femoral Vein up to 
the level of the inguinal ligament. Below, in Hunter’s canal, the femoral vein 
lies behind and somewhat to the outer side of its artery, but, as it ascends, it THE VEINS. 
483 
crosses obliquely behind the artery, so as to be internal to it in the upper part of 
Scarpa’s triangle. It is joined by tributaries corresponding to the branches of 
the artery, including the Deep Femoral Vein (which ascends in front of its artery), 
and also, near its upper end, by the internal saphenous vein. It contains three 
or four valves, one of which is just above the opening of the profunda vein, and 
another just below the inguinal ligament. At its upper end it is separated inter- 
nally from the crural canal by a thin septum of fascia, passing between the front 
and rear walls of the femoral sheath. THE LYMPHATIC SYSTEM. 
By F. H. GERRISH. 
THE lymphatic system begins in the microscopic crevices between the cells 
and fibres of almost all tissues. These diminutive spaces are called “juice 
channels” or “juice canals/’ because they are the receptacles of the fluids which 
exude from the adjacent blood-vessels and tissues. They communicate very 
freely among themselves, and also with the beginnings of the capillary tubes, 
which are the radicles of the lymph-vessels, and into the latter they discharge 
their contents. 
THE LYMPH-VESSELS. 
The plan upon which the lymphatics are constructed is almost identical with 
that of the venous system. The small vessels unite and form larger, these in 
turn act as the radicles of others of still greater size, and after this manner the 
Fig. 513.—Epithelium lining lymph- 
vessel. (Testut.) 
Fig. 514.—Lymph-vessel laid open 
lengthwise, showing arrangement of 
valves. 
process continues until the largest tubes are reached. There is constant increase 
in size and diminution in number from the periphery to the centre of the system. 
But the lymphatics are much smaller than the corresponding veins. Upon the 
surface of the body frequent plexuses of minute vessels are found, which present 
an intricate and very delicate reticular appearance. 
All lymph-vessels contain lymph, and those of the small intestine at certain 
484 LYMPHATIC SYSTEM. 
485 
Fig. 515—The regions whose lymph flows into the right lymphatic duct are suggested by the red area; those 
which are tributary to the thoracio.duct by the blue. (F. H. G.) 486 
THE LYMPHATIC SYSTEM. 
times carry chyle also (see page 57). The chyle-bearing lymphatics do not differ 
structurally from other vessels of the system ; but they are often called laeteals 
(literally “ pertaining to milk”) because, during the period of intestinal digestion, 
when they are filled with chyle, which is white, they look as if distended with 
milk, whose Latin name is lac. 
The course of the fluid in the lymphatics is always from the periphery toward 
the centre, the materials being sucked up, as it were, in the distal parts of the 
body, and carried proximally. Consequently the lymphatic system is often spoken 
of as “ the absorbent sys- 
tem.” But this is an 
undesirable name, inas- 
much as the veins, also, 
do considerable absorption 
work. 
A close relationship 
has long been recognized 
between the lymphatics 
and the true serous mem- 
branes. These closed sacs 
arc to be regarded as 
prodigiously expanded 
lymph-spaces, and are 
sometimes and appropri- 
ately called lyrnjdi-cham- 
bers. The true stomata 
of these serous membranes 
are the mouths of lymph- 
atic vessels. The recog- 
nition of this continuity 
of lymphatic and serous 
surfaces is of great physio- 
logic and pathologic im- 
portance. 
UPPER END OF 
'THORACIC DUCT 
The Structure of 
Lymph-vessels.—The 
lymphatics resemble the 
veins in their structure, 
as well as in their arrange- 
ment. The smallest have 
but a single coat, com- 
posed of epithelial cells 
with notched edges, which 
fit accurately with those 
of the adjacent cells (Fig. 
513). The larger vessels 
have three tunics: an inner 
one of epithelium (like that described above) and a little yellow fibrous tissue; a 
middle, made up of muscular and yellow fibrous tissues ; and an outer, consisting 
of white fibrous tissue, with which is mixed a small amount of yellow. All 
of the coats are so thin as to be transparent. At very short intervals are 
valves, formed by folds of the lining membrane (Fig. 514). The position of 
a valve is marked by a circular constriction, proximal to which is a pronounced 
bulge ; and in this way a peculiar beaded or moniliform (“ necklace-like ”) appear- 
ance is produced. The valves prevent backward flow of the lymph. 
The lymphatics are divided into two sets, the superficial and the deep, accord- 
ing to their situation. The superficial lymph-vessels course in the subcutaneous 
areolar tissue. In the limbs they are more abundant upon the inner and flexor 
ASCENDING LUMBAR'' 
Fig. 516.—The thoracic duct and right lymphatic duct. (Testut.) L YMPH-NODES. 
487 
aspects than upon the outer and extensor. They are especially numerous at the 
junction of the skin with mucous membrane. The deep lymph-vessels accompany 
the blood-vessels. There is free communication between the vessels of the same 
set; but there is no connection between the superficial and deep, except as they 
empty into the same nodes. 
Ultimately the lymphatics end in veins; and thus the lymphatic system is 
seen to be an adjunct to the blood-vascular system. The lymph mingles with the 
venous blood, and the leucocytes, which were lymph-corpuscles a moment ago, 
are colorless blood-corpuscles now. 
There are two points at which the lymph is poured into the blood, one on each 
side, where the internal jugular and subclavian veins unite to form the brachio- 
cephalic (Fig. 516). On the right side the vessel, called the right lymphatic duct, 
is an inch or less in length, and receives the lymph from the right side of the 
head, neck, and chest, the right lung, the right heart, the right upper limb, and 
the upper surface of the liver. A double valve guards its proximal opening. On 
the left side the vessel, called the left lymphatic duct, or, more commonly, the 
thoracic duct, is a large trunk, which has its tributaries in all portions of the body 
not just enumerated. The parts drained by each are suggested with practical 
accuracy by a glance at Fig. 515. The thoracic duct begins in a pear-shaped 
dilatation, called the receptaculum chyli, situated in front of the second lumbar 
vertebra. It runs upward at the right of the aorta to the level of the fourth 
thoracic vertebra, where it passes behind that great vessel and the left subclavian 
artery, and then arches outward and downward to its termination. It is as large 
as a goose-quill, and from fifteen to eighteen inches long. It has numerous 
valves, a double one standing at its junction with the venous system. 
LYMPH-NODES 
AND OTHER LYMPH ADEN OID STRUCTURES. 
Besides the lymph-vessels, which have just been described, the lymphatic 
system comprises a large amount of a compound tissue, known as lymphadenoid 
tissue. The framework of this material is adenoid reticular tissue (see page 50), 
and in its meshes are irregular masses of leucocytes. This lymphadenoid tissue 
exists in several forms, which differ from each other mainly in the degree of their 
compactness, some being firm, well-defined, and encapsuled, others extremely 
diffuse, and still others presenting various stages intermediate to these. 
Sometimes, as in the mucous membrane of the intestines, the peculiar material 
is infiltrated, has no clearly defined boundaries, and hence is called diffuse lymph- 
adenoid tissue. It is a mere network of adenoid reticular tissue enclosing colorless 
corpuscles. A step beyond this condition occur small masses in the submucous 
or subserous membrane, distinctly defined, and encircled by a series of lymph- 
vessels. A typical example of this class is seen in the so-called solitary glands 
of the intestine. When a number of such bodies are grouped into a coherent 
mass, the resulting structure is known as an agminated gland. Somewhat more 
distinct aggregations of lymphadenoid tissue, encased in a well-marked capsule, 
are frequently found located in small depressions in mucous membrane, illustra- 
tions of which are seen in the tongue, the tonsils, and the pharynx. 
The most sharply defined collections of lymphadenoid tissue are the lymph- 
nodes—commonly, but less appropriately, called lymphatic glands. They are 
not, as are the varieties mentioned above, connected directly with a mucous sur- 
face ; they always are furnished with a distinct capsule, which maintains their 
characteristic form ; and they always occur in the course of lymph-vessels. 
LYMPH-NODES. 
A lymph-node (Fig. 517) is a small, roundish or ovoid body, situated in the 
course of a lymph-vessel. Upon its proximal aspect is usually a little depression 488 
THE LYMPHATIC SYSTEM. 
or notch, called the kilum, at which its arteries enter, and its veins and efferent 
vessels emerge. The capsule of the node is mainly composed of white fibrous 
tissue, but has a slight admixture of smooth muscular tissue. From its inner 
surface trabeculae (“little beams”) project toward the centre of the node, these 
being broad and shelf-like at the periphery, which is called the cortex (“ bark ”), 
but narrow and like slender rafters in the central portion, the medulla 
(“ pith ”). In no part are the spaces which these 
enclose completely circumscribed, and thus, as in 
areolar tissue, there is free intercommunication be- 
tween them. The irregular spaces are occupied by a 
rather solid mass of pulp, which, however, does not 
quite fill them, as it never touches the capsule and 
trabeculae, but leaves a narrow interval between itself 
and them. This open interval, which appears in a 
section of the node like a channel, is the lymph sinus, 
and is crossed by a network of delicate adenoid 
reticular tissue, which is continuous on the one hand 
with the trabeculae or capsule, and on the other with 
a still finer plexus of the same character, which per- 
vades the pulp and forms the framework upon which 
the essential constituents of the pulp are supported. 
The pulp or proper substance of the node is a 
mass of leucocytes, held together by the fine reticulum 
just mentioned. The cells at the periphery of the 
collection are in a condition of multiplication bv 
karyokinesis, and it is believed that the newly formed 
cells are continually liberated into the lymph sinus. 
The lymphadenoid tissue is well supplied with blood- 
vessels. 
The lymph sinus is a complicated series of freely com- 
municating passages into which a number of lymph- 
vessels pour their contents, and from which a smaller 
number of lymph-vessels receive lymph. The inner coat of the entering {afferent) 
and emerging {efferent) vessels is continuous with the epithelial lining of the 
lymph sinus and the epithelial covering of the trabeculae which traverse it. Thus 
there is no breach in the continuity of the surface over which the lymph flows, 
whether it is in the vessels or in the channels of the nodes. 
Fig. 517.—A lymph-node with 
its afferent and efferent vessels. 
(Testut.) 
The nodes, with the exception of the superficial inguinal, are situated beneath 
the deep fascia, though not always under its immediate covering. All told 
there may be nearly 700 nodes, of which the greatest part are in the chest- and 
belly-cavities. The face and neck have a considerable number, the limbs a few, 
and the brain-case none. In size they vary from that of a large bean to such 
diminutiveness that they escape gross observation, unless they have become 
enlarged by disease. In the groin they can easily be felt, but not in the axilla. 
Those of very small size are called nodules. 
As age creeps on, the lymphatic tissues undergo senile atrophy. The thymus 
gland, whose nature is essentially lymphatic, diminishes and generally entirely 
disappears before adult life. The ordinary lymph-nodes gradually shrink in old 
age, though they do not altogether vanish, and all of the other lymphatic struct- 
ures pursue a similar degenerative course. 
The effect of lymphadenoid tissue upon the lymph which passes through it is 
very marked. For example, the lymph which enters a node has fewer corpuscles 
and less albuminoid material than that which flows out of it. We thus see that 
the influence of the node is toward the enrichment of the lymph. Extraneous 
matters absorbed by the lymph-vessels from the juice-channels are caught in the 
reticular tissue, which crosses the sinus, and are detained temporarily or even 
permanently. When these particles are bacteria they are liable to set up patho- NODES OF THE HEAD AND NECK. 
489 
logic processes. The nodes act as sieves, which prevent to a considerable extent 
the infection of parts proximal to themselves. 
The great majority of the nodes are arranged in colonies, a few stand singly 
by themselves. Each node or group of nodes receives lymph from fairly well- 
defined areas and parts. But at the periphery of these areas or parts abundant 
inosculation with vessels of contiguous regions occurs, and along the boundary 
lines the lymph may flow into one or the other, or even into both sets of vessels. 
A single organ may be supplied with lymph-vessels which are tributary to two 
or even more groups of nodes, as, for example, the uterus, the mamma, the penis, 
the pericardium. 
It is of great importance that the sources of supply of lymph for each colony 
of nodes should be well understood, on account of their frequent infection by the 
absorption of disease materials. When a single node or colony is invaded by 
pathologic germs, attention is immediately directed to the region in which must 
be sought the lesion by which toxic material has been introduced. Consequently, 
it is evident that the most useful, because the most practical, method of studying 
the lymphatic system is to ascertain what groups of nodes there are, and what 
vessels are tributary to each of them. The accompanying diagrams have been 
devised with the idea of supplementing the verbal descriptions by graphic repre- 
sentations, and of enabling one to see at a glance what region or regions to 
examine for lesions when any particular colony of nodes is diseased. As has 
been already remarked, the frequent anastomoses of vessels at the boundaries of 
contiguous regions should be borne in mind; and additionally it must be remem- 
bered that the nodes of each group communicate freely with each other, and that 
every cluster of nodes is more or less intimately connected with its neighbors. 
The nodes will now be studied systematically according to the regions in which 
they are situated, and will be taken up in the following order : nodes of the head 
and neck; nodes of the upper limb ; nodes of the lower limb; nodes of the 
thorax ; nodes of the abdomen. 
In every surgical operation involving the cutting of soft parts, lymphatic 
vessels are necessarily severed; but, unless the thoracic duct or the right lymph- 
atic duct is wounded (and these accidents are very rare) the results are trivial. 
The lymph-vessels generally are so small and so delicate that it is impossible to 
see them in ordinary, normal conditions, and, consequently, it is impracticable to 
avoid them. Therefore, it seems undesirable to burden the following descriptions 
with the exact course pursued by the majority of the small lymphatics. The 
situation of the several colonies of nodes will be described, the areas and organs 
which drain into each enumerated, and the destination of its efferents mentioned; 
and these are the essential practical points of the subject. 
THE NODES OF THE HEAD AND NECK 
and their Tributary Vessels. 
The nodes of the head and neck (Figs. 518, 519) are so intimately associated 
that it is most convenient to consider them together. 
The Deep Cervical Nodes.—The most numerous series is the deep cervical chain, 
which lies along the course of the internal jugular vein. Into this group, either 
directly or indirectly, is poured the lymph from the entire head and neck. It is 
divided into two sets—the upper deep cervical and the lower deep cervical—the 
first extending from the base of the skull to the level of the upper border of the 
thyroid cartilage, the second reaching from that line to the clavicle. The upper 
deep cervical nodes receive immediately the efferents of the parotid, the internal 
maxillary, the submaxillary, the suprahyoid, and the lingual nodes, and the 
vessels from the deep muscles of the head and neck, the tonsil, the thyroid body, 
the lower part of the pharynx, and the upper portion of the larynx. The lower 
deep cervical nodes take the lymph from the upper deep cervical and the super- 
ficial cervical, the lower part of the larynx and thyroid, the upper parts of the 490 
THE LYMPHATIC SYSTEM. 
trachea and oesophagus, and the inferior portions of the neck. The efferents 
of the deep cervical nodes connect with the superior mediastinal and axillary 
nodes. 
The Superficial Cervical Nodes.—The superficial cervical nodes follow the line 
of the external jugular vein, occupying the posterior triangle of the neck. Their 
atferents come from the snboccipital, mastoid, and submaxillary nodes, the integu- 
ment of the neck and that of the external ear. Their efferents run to the lower 
deep cervical. 
The Suhoccipital Nodes lie just below the superior curved line of the occipital 
bone, taking lymph from the back part of the scalp, and passing it along to the 
mastoid and superficial cervical nodes. 
Fig. 518.—The lymph-nodes of the neck and upper part of the thorax. (Testut.) 
The Mastoid Nodes are located behind the ear, drain the scalp in that region, 
and receive efferents from the snboccipital nodes. Their lymph goes to the super- 
ficial cervical. 
The Submaxillary Nodes form a chain below and about parallel with the under 
margin of the mandible. They gather the lymph from the submaxillary and sub- 
lingual salivary glands, the lips, the front part of the tongue, the floor of the 
mouth, the nose, the frontal region, and the nasal half of both eyelids. The 
buccal nodes, which are situated upon the outer surface of the buccinator muscle, 
interrupt the flow in some of the vessels that bring lymph from the fore part of 
the face. The efferents of the submaxillary nodes empty into the upper deep 
cervical and the superficial cervical. 
The Suprahyoid Nodes, which lie between the anterior bellies of the digastric 
muscles, are sometimes counted as belonging to the submaxillary group. They 
collect lymph from the middle of the lower lip and from the chin, and pour it 
into the upper deep cervical. NODES OF THE HEAD AND NECK. 
491 
Connects with 
Axillary Nodes 
Connects with 
Superior 
Mediastinal Nodes 
Fig. 519.—Diagram of the nodes and vessels of the head and neck, showing the regions which are drained 
into each group of nodes. Deep structures in red, superficial in black. (F. H. G.) 492 
THE LYMPHATIC SYSTEM. 
The Parotid Nodes are situated in the region of the ear, some being superficial 
to the great salivary gland, and others being deep in its substance. They derive 
their lymph from the outer surface of the cheek, the outer half of the lids, the 
brow, the parietal and temporal regions, all of the parts within the brain-case, 
and the post-pharyngeal nodes. 
They send the lymph to the 
upper deep cervical nodes. (Wal- 
sham says that their efferents 
terminate in the submaxillary 
and superficial cervical.) 
DEEP CERVICAL NODE 
The Post-pharyngeal Nodes 
are placed behind the uppermost 
part of the pharynx. Their 
lymph comes from the hind part 
of the nasal cavity, the roof of 
the pharynx, and the preverte- 
bral muscles, and goes to the 
parotid nodes. 
The Internal Maxillary Nodes 
are situated at the side of the 
anterior part of the pharynx. 
Its afferents bring lymph from 
the orbit, the greater part of the 
nasal cavity, the upper jaw, the 
roof of the mouth, the soft pal- 
ate, the deep surface of the 
cheek, and the largest portion 
of the pharynx ; and its efferents 
carry the lymph to the upper 
deep cervical. 
The Lingual Nodes, located on 
the side of the tongue, get their 
lymph from the back part of 
that organ, and empty it into 
the upper deep cervical nodes. 
PROPER AXILLARY 
NODES 
- EPICONDYLAR NODE 
THE NODES OF THE UPPER 
LIMB 
and their Tributary Vessels. 
The Axillary Nodes (Figs. 
520, 521) comprise four tolerably 
distinct groups: the axillary 
proper, arranged around the 
great vessels of the armpit; the 
pectoral, in the course of the 
long thoracic artery; the sub- 
scapular, along the subscapular 
artery; and the subclavian, on 
the costo-coracoid membrane, between the deltoid and greater pectoral muscles. 
There exists a free communication not only between the nodes of each set, but 
between the different groups ; so that infection of any one may extend to all of 
the others. The efferents of all of these groups discharge into the thoracic duct 
or the right lymphatic duct. 
The proper axillary nodes collect the lymph from the epicondylar node, the 
entire arm, except the surface of the outer side, and all of the forearm and hand, 
except a portion of the surface which drains into the epicondylar node. 
-PALMAR PLEXUS 
Fig. 520.—The nodes and vessels of the upper limh. (Testut.) NODES OF THE LOWER LIMB. 
493 
The pectoral nodes drain the greater part of the mammary gland, the integu- 
ments of the side and front of the chest, and those of the abdomen above the 
level of the navel. 
The subscapular nodes receive lymph from the superficies of the back of the 
neck, the shoulder, and most of the trunk above the crest of the ilium. 
The subclavian nodes derive their lymph from the skin of the deltoid region 
and the outer aspect of the arm. They connect with the deep cervical. 
Fig. 521.—Diagram of the nodes of the right upper limb and their superficial tributaries, showing the areas 
drained by each group. Deep structures in red, superficial in black. (F. H. G.) 
The Epicondylar Node, situated above the internal condyle of the humerus, 
gets its lymph from the inner portion of the surface of the hand and forearm, 
and its efferents carry it to the proper axillary nodes. 
THE NODES OF THE LOWER LIMB 
The nodes of the lower limb (Figs. 522, 523) are the superficial and deep 
inguinal, the popliteal, and the gluteal. 
The Superficial Inguinal Nodes are arranged in two series—a superior or oblique, 
and an inferior or vertical. 
and their Tributary Vessels 
The superior set is situated close to the inguinal ligament, and is subdivided 
into three groups—the external, the middle, and the internal—each comprising 
about three nodes. Their lymph comes from the integuments of the buttock 
and the skin around the anus, the lower and outer part of the back above the 
buttock, the belly below the level of the navel, and the penis (Fig. 524); also 
from the distal portion of the urethra in both sexes, and from the vulva and the 
lower third of the vagina in the female. The scrotum and the superficial portion 494 
THE LYMPHATIC SYSTEM. 
of the perineum frequently drain into this set; and occasionally vessels from the 
uterus end in it. 
The inferior set is situated at the saphenous opening. It takes the lymph 
from the superficial parts of the thigh, and of the entire leg and foot, except their 
outer side ; also from the scrotum and the integu- 
ments of the perineum, and sometimes the penis, 
vulva, urethra, and lower part of the vagina. 
The superficial inguinal nodes discharge jjartly into 
the deep inguinal and partly into the external iliac. 
The Popliteal Nodes, located deeply in the ham- 
space, get their lymph from the surface of the outer 
side of the leg and foot, and the deep structures of 
the same segments of the limb. Their efferents join 
the deep lymphatic vessels of the leg. 
The Deep Inguinal Nodes are grouped around the 
upper end of the femoral artery and vein. Their 
afferent vessels come from the superficial inguinal 
nodes and from the deep structures of the greater 
part of the limb ; and their efferents run to the ex- 
ternal iliac nodes. 
Fig. 522.—The nodes and vessels 
of the lower limb. (Testut.) 
Fig. 523.—Diagram of the superficial inguinal and the popliteal 
nodes of the right side and their superficial tributaries, showing areas 
drained by each subgroup. Deep structures in red, superficial in 
black. Frequent variations in dotted lines. (F. H. G.) 
The Gluteal Nodes, lying near the pyriformis muscle, derive their lymph from 
the deep parts of the buttocks, and transmit it to the internal iliac nodes. NODES OF THE THORAX. 
495 
..PLEXUS ON 
CLANS 
CIRCULAR VESSELS 
AROUND CERVIX 
... FASCIA 
DEEP DORSAL 
MEDIAN TRUNK 
SUPERFICIAL 
..SUPERFICIAL 
VESSELS 
SUPERFICIAL DORSAL.. 
VESSELS 
MEDIAN TRUNK 
Fig. 524.—The lymph-vessels of the penis. (Testut.) 
THE NODES OF THE THORAX 
and their Tributary Vessels. 
The nodes of the thoracic cavity (Fig. 525) are all deep, and derive their 
lymph from deep structures; that is, not at all from integumentary organs. They 
are disposed in the following groups : the sternal, the intercostal, the anterior 
mediastinal, the posterior mediastinal, the superior mediastinal, the bronchial, 
and the vena-caval. They discharge into the thoracic and right lymphatic ducts. 
The Sternal Nodes lie in the spaces between the costal cartilages close to the 
borders of the breast-bone. Lymph flows to them from the deep portions of the 
mammary glands, from the anterior and lateral walls of the chest, from the upper 
part of the front and sides of the abdominal walls, from the diaphragm, and from 
the anterior mediastinal nodes. 
The Intercostal Nodes are lodged in the hindmost part of the intercostal spaces. 
They drain the thoracic part of the spinal canal, the costal pleurae, and the poste- 
rior and lateral portions of the chest-walls. 
The Anterior Mediastinal Nodes are situated in front of the heart. Their 
lymph comes from the pericardium, the diaphragm, the liver, and the sternal 
nodes, and goes partly directly to the great terminal vessels of the system, and 
partly to superior mediastinal and sternal nodes. 
The Posterior Mediastinal Nodes, located around the aorta, have afferents from 
the heart, the pericardium, the lower part of the oesophagus, and the diaphragm, 
and communicate freely with the bronchial nodes. 
The Superior Mediastinal Nodes lie in front of the arch of the aorta. Their 
tributaries come from the thymus gland, the heart, the pericardium, the anterior 
mediastinal and the bronchial nodes. There is a direct connection between this 
group and the deep cervical nodes. 
The Bronchial Nodes (Fig. 518), gathered at the roots of the lungs, take lymph 
from the lungs, the pulmonary pleurae, the lower part of the trachea, the bronchi, 
the bronchioles, and the pericardium, and communicate with the superior and the 
posterior mediastinal nodes. Fig. 525 Diagram of the nodes of the trunk and their tributary vessels. (F. H. G.) 
496 NODES OF THE ABDOMEN. 
497 
The Vena-caval Nodes, few and small, are placed close to the upper end of the 
inferior vena cava. Yessels from the upper and hind part of the liver perforate 
the diaphragm, and discharge into them. 
THE NODES OF THE ABDOMEN 
and their Tributary Vessels. 
Like the thoracic, the abdominal nodes (Fig. 525) are all deep, and, with a 
single exception, their immediate source of lymph is other than superficial. They 
are arranged in the following groups : the mesenteric, the mesocolic, the coeliac, 
the hepatic, the gastric, the splenic, 
the median lumbar, the lateral lum- 
bar, the external iliac, the internal 
iliac, the sacral, and the rectal. 
The Mesenteric Nodes (Fig. 526), 
lodged between the layers of the 
mesentery, take the lymph from the 
small intestines through the lacteal 
vessels. They discharge by a large 
trunk into the receptaculum chyli. 
The Coeliac Nodes, grouped in 
the region of the coeliac axis, re- 
ceive lymph from the liver and 
the gall-bladder, the stomach, the 
pancreas, the spleen, and the great 
omentum, and empty it into the efferent trunk of the mesenteric. In the course 
of the vessels Avliich carry lymph from the liver, stomach, and spleen to this group 
are small nodes, called respectively hepatic nodes, gastric nodes, and splenic nodes. 
The Mesocolic Nodes lie between the layers of the mesocolon. Their afferents 
come from the csecum, the ascending and transverse colon, and the upper portion 
of the descending colon ; and their efferents run to the mesenteric efferent trunk. 
The Median Lumbar Nodes are situated close to the abdominal aorta. Their 
supply of lymph comes from the body of the uterus, the ovaries and the Fallo- 
pian tubes, the testicles, the kidneys, the ureters, the diaphragm, the suprarenal 
bodies, the external iliac, internal iliac, sacral and lateral lumbar nodes ; and 
the trunk by which they discharge into the receptaculum is joined by the efferents 
of the lower part of the descending and the whole of the sigmoid colon. 
The Lateral Lumbar Nodes lie in the spaces between the transverse processes 
of the lumbar vertebra?. Their afferents come from the lower part of the spinal 
canal, and the dorsal and lateral portions of the abdominal Avails; and their 
efferents run to the median lumbar nodes and the receptaculum. 
The External Iliac Nodes, situated along the line of the external iliac vessels, 
take lymph from the ventral and lateral parts of the Avails of the abdomen, and 
from the superficial and deep inguinal nodes. They have a communication Avith 
the internal iliac nodes, and discharge into the median lumbar. 
The Internal Iliac Nodes, lying around the internal iliac vessels, have tribu- 
taries from the deep parts of the penis, the proximal portion of the urethra, the 
bladder, the prostate, the neck of the uterus, the upper two-thirds of the vagina, 
the deep layers of the perineum, the pelvic muscles, the adductor region of the 
thigh, and the gluteal nodes. They send their lymph to the median lumbar 
nodes, and haATe connection with the external iliac. 
Fig. 526.—Mesenteric nodes. (Testut.) 
The Sacral Nodes, situated in the curve of the sacrum, have afferents from the 
dorsal and lateral pelvic parietes and from the rectal nodes, which take their 
lymph from the rectum. THE CEREBROSPINAL AXIS 
F. H. GEBRISH. 
THE great nervous mass which occupies the main cavity of the cranium is 
known as the encephalon (“ in the head”) or brain; and the prolongation of 
this, which is lodged in the canal made by the vertebrse and the cartilaginous plates 
between them, is called the myelon (“marrow”) or spinal cord. Radiating from 
these structures are many cords, called nerves; 
and this fact suggested the name axis for these 
combined central organs, the distinguishing 
CERE-.t< 
brum" 
OBLON-,. 
GATA 
f CERE- 
BELLUM 
Fig. 528.—Diagram of the conversion of the dorsal 
groove into a canal. 
adjective cerebrospinal, which is usually asso- 
ciated with the noun, deriving its first part from 
“cerebrum,” which is the 
most conspicuous portion 
of the encephalon, and 
its last part from the 
column of bones in which 
the myelon is located 
(Fig. 527). 
The cerebro-spinal 
axis is first observed in 
the embryo as a longi- 
tudinal groove on its dor- 
sal aspect. Its edges 
grow up at the sides, 
curve toward the mid- 
line, meet there, and fuse together (Fig. 528), The result 
is that the gutter is changed into a tube. One end of the 
tube enlarges into a sac, and this develops into the enceph- 
alon (Fig. 529). The> remainder of the tube becomes the 
spinal cord. The cavity of the encephalon is always con- 
tinuous with that of the spinal cord. 
Great changes take place in both parts, especially in 
the encephalon ; but throughout these modifications, cer- 
tain things are almost invariable. In nearly all of the 
amazing complications of encephalic growth, three things remain as in the simplest 
form of encephalon in the embryo ; (1) a cavity-wall of nervous tissue; (2) a 
Fig. 527.—Semidiagrammatic view of 
the cerebro-spinal axis, left side. (Testut.) 
Fig. 529.—Diagram of first 
stage of axial cavity. 
499 500 
THE CEREBROSPINAL AXIS. 
lining of epithelium; and (3) a membranous covering, which is essentially a net- 
work of blood-vessels (Fig. 530). 
(1) The nervous substance is gray, or white, or both of these. In different 
parts this nervous wall receives distinguishing names—gyrus, lamina, nucleus, 
commissure, etc. 
(2) The lining is serous in character, and secretes a watery fluid, which 
moderately fills the entire cavity. The membrane is called ependyma, or merely 
Fig. 530.—Diagram of transverse section of 
typical wall of cavity of cerebro-spinal axis. 
Fig. 531.—Diagram of transverse section of axis, 
where a portion of the nervous wall has disap- 
peared, allowing pia and endymato come together. 
endyma (“ garment ”). The fluid is called cerebrospinal fluid, or cephalo-rachidian 
fluid. 
(3) The covering sends nutrient vessels into the substance of the wall, and is 
called the pia, or pia mater (“ the tender mother ”). 
The solid wall may grow to a thickness of several inches, it may dwindle to 
the thinness of paper, or it may even disappear altogether (Fig. 531); but 
endyma and pia are persistent. The endyma is a perfect shut sac, save for a 
diminutive aperture at a single 
point, by which a communication 
is established with another serous 
cavity lying outside of the axis. 
Real comprehension of the subject 
cannot be acquired without appre- 
ciation of these primary conditions, 
here repeated : that the encephalon 
is a hollow organ, filled with fluid; 
that it has everywhere a serous lin- 
ing ; that it has a vascular plexus 
for its outer investment; and that it 
has nearly everywhere between its lin- 
ing and its covering a solid wall of 
nervous tissue, which varies im- 
mensely in thickness in different 
parts. 
FIRST 
VESICLE 
SECOND 
VESICLE 
THIRD 
VESICLE 
' ANTERIOR 
ENCEPHALIC 
VESICLE 
MIDDLE ' 
ENCEPHALIC 
VESICLE 
FOURTH 
VESICLE 
FIFTH 
VESICLE 
The encephalon, at first a single 
vesicle, soon becomes elongated, and 
then constricted circularly and 
deeply at two equidistant points. 
In this way three secondary vesicles 
are formed (Fig. 532). They do 
not, however, long remain in this condition ; for, while the middle one continues 
single, the front one and the rear one are soon constricted transversely and 
divided, each forming two. Thus, there is a series of five vesicles of sub- 
POSTERIOR ' 
ENCEPHALIC 
VESICLE , 
Fig. 532. Diagram 
of the three secondary 
vesicles of the hrain. 
Fig. 533.—Diagram of the 
five ultimate vesicles of the 
brain. 501 
THE CAVITY OF THE CEREBROSPINAL AXIS. 
stantially equal size, whose cavities communicate through central apertures (Fig. 
533). These five vesicles are the primary forms of the five grand divisions of 
the adult encephalon, and are named in order, from before backward, 'prosenceph- 
alon, diencephalon, mesencephalon, epencephalon, and metencephalon. The first 
and second show a tendency in the developed state to revert to their original con- 
dition of unity, and the same is true of the fourth and fifth ; but the third remains 
single and distinct from its earliest appearance to its most complete development. 
Vernacular names also are given them—forebrain, betweenbrain, midbrain, 
hindbrain, afterbrain—but only the first of them is so clearly descriptive as to 
convey infallibly the idea intended, and it would be better to discard them for 
the technical appellations, which, while etymologically not greatly superior, are 
widely used by the scientific with definite meanings, and are understood by all 
anatomists. 
When these vesicles are first observed, they are, as has been said, about equal 
in size and very similar in form ; but the likeness which they bear to each other 
does not long continue : they grow at very different rates of speed, and, when 
fully developed, are so dissimilar in appearance that it is difficult to understand 
that they could have been of almost identical shape and bulk at any former 
period. Some parts, which are brought into close contact with others, seem to 
blend; while others, in nearly similar conditions, undergo shrinkage, and finally 
disappear. 
THE CAVITY OF THE CEREBRO SPINAL AXIS. 
Let us first consider the cavity of the cerebro-spinal axis, ignoring for the 
while the enclosing walls ; and, when we have gained a comprehension of this, 
we can proceed more to the study of the surrounding solid material. 
Suppose the cavities of the five encephalic vesicles to be of equal size, and 
that of the spinal cord to be a cylindrical continuation from the fifth or hindmost 
vesicle. We have then, to start with, a series of chambers, each communicating 
freely with the one next behind it. This continuity of the cavities is always 
maintained, even though 
the original chambers un- 
dergo alterations of form 
so prodigious that only a 
very slight resemblance to 
the primitive shape re- 
mains. 
FIRST 
VESICLE 
FIRST 
VESICLE 
For the sake of sim- 
plification we will first 
examine the subject dia- 
grammatically, taking the 
vesicles one by one in 
regular order ; and, in con- 
sidering each, we will 
V E SIC L E 
SECOND 
Fig. 534.—Diagram of the 
formation of the port*. 
Fig. 535.—Diagram of the formation 
of the bodies of the lateral ventricles. 
ignore as far as possible the changes which in nature take place in its immediate 
neighbors synchronously with those in itself. 
To begin with we have the first vesicle, the most anterior—the prosencephalon 
—which ultimately becomes the cerebral hemispheres. From the upper and 
front part of its globular cavity on each side a little sprout is put forth (Fig. 
534). The distal end of this protrusion enlarges, and becomes of much greater 
size than the parent cavity (Fig. 535). Then each of the new appendages sends 
out a prolongation forward, a second backward, and a third which curls sidewise 
and downward. These, from their shape, are called horns or cornua (Fig. 536). 
In this process of enlargement the original vesicle is so far outgrown by its off- 
shoots that it is in great danger of being lost sight of. The chief cavity on each 
side is called a ventricle, and, from its being at the side, lateral. Of the lateral 502 
THE CEBEBBO-SPINAL AXIS. 
ventricle the main part is known as the body, and the prolongations from it are 
named respectively anterior horn, middle or descending horn, and posterior horn. 
The original sprout now serves for a passage of communication between the 
primary vesicle and the ventricle, and is known commonly as the foramen of 
Monro; hat it is better designated as porta (“the doorway”). The original 
cavity of the vesicle, now subordinate in extent to the large chambers to which 
it has given rise, is called aula (“ the hall”). Thus we have from the cavity of 
the first vesicle the following parts : the aula in the centre, and on each side a 
porta, and a lateral ventricle with its three horns (Figs. 536, 537). Notice that 
the aula is distinctly below the plane of the body of the ventricle, and that the 
middle horn descends to a level much below that of the aula. 
FIRST 
VESICLE 
(AULA) 
Fig. 536.—Diagram of the full development of the lateral ventricles and their cornua—view from above. 
Passing to the cavity of the second encephalic vesicle—the diencephalon—we 
find that it considerably outgrows the aula, which is just in front of it. Its 
enlargement is very slight sidewise and is almost entirely up-and-down and 
backward, as if the vesicle had been squeezed between two vertical planes at the 
sides (Figs. 538, 539). The result of this development is to make the second 
vesicle a long, deep, narrow chink in the middle line—a fore-and-aft median 
crevice, with the aula in front and the third vesicle behind. The original con- 
striction between this cavity and that of the first vesicle becomes practically 
BODY OF 
LATERAL VENTRICLE 
FIRST 
VESICLE 
Fig. 537.—Same as Fig. 536—view from the left side. 
obliterated, and, consequently, the cavities of the aula and the second vesicle merge 
into one, the greater portion of which is contributed by the second vesicle, that 
furnished by the first vesicle being located at the upper and fore part. This 
composite cavity, made of the whole of the second and a part of the first vesicle, THE CA VITY OF THE CEREBROSPINAL AXIS. 
503 
is usually called the third ventricle, the first and second ventricles being the 
lateral, which are never designated in a numerical way, but always as right 
lateral ventricle and left lateral ventricle. It will now be seen that the third 
ventricle communicates with each lateral ventricle by a separate porta. 
Next we study the cavity of the third encephalic vesicle—the mesencephalon. 
This assumes a shape as if it were stretched between its neighbor in front and 
the one behind ; it is drawn out into a small tube, and thus constitutes a long 
and narrow channel from the vesicle before to that behind (Fig. 540). It is 
named the aqueduct (aqueductus Sylvii—from Sylvius, a celebrated anatomist), 
and also by another name, which will be better understood 
a little later. 
V E S 1 C L. F 
The cavity of the fourth encephalic vesicle—the epencephalon 
—instead of retaining its globular shape, is 
flattened from above downward, as if it had 
been compressed between plane surfaces applied 
obliquely to its dorsal and ventral aspects; 
FiR S T 
V SIC L ti 
THi R D 
SECOND 
VESICLE 
FOU R T H 
YES! C L E 
Fig. 588.—Diagram 
of changes in second 
vesicle—view from 
above. 
Fig. 539.—Same as Fig. 538—view from left side. 
Fig. 540,—Diagraiii 
of changes in third 
vesicle. 
and it is widened out behind, assuming a triangular term, the apex being tor- 
ward (Figs. 541, 542). A little of the constriction between it and the fifth 
vesicle is still observable, even in the developed condition. 
The cavitv of the fifth encephalic vesicle—the metencephalon—undergoes 
changes in its fore part almost identical with those 
experienced by that of the fourth; but the triangle 
which it forms has its base forward, applied to the 
base of the triangle of the fourth vesicle, and its apex 
backward, and the obliquity of the surfaces is oppo- 
site to that of those of the fourth (Figs. 543, 544). 
Thus, the two vesicles form a single shallow cavity 
FOURTH 
VESICLE 
FOURTH VESICLE 
Fin. 541.—Diagram of changes 
in fourth vesicle—view from above. 
Fig. 542.—Diagram of changes in fourth vesicle—view from left side. 
of rhomboidal form, when viewed from above. The hind part of this fifth vesi- 
cle is drawn out into a tube, and is continuous with the cavity of the myelon. 
The combined cavities of the fourth and fifth vesicles form what is commonly 
known as the fourth ventricle. We note that this fourth ventricle is connected 
with the third ventricle by the aqueduct, the other name of which, promised 504 
THE CEREBROSPINAL AXIS. 
above, can now be appreciated. It is iter a tertio ad quartum ventriculum (“the 
passage from the third to the fourth ventricle”), a name with the merit of 
descriptiveness, but with the fault of tiresome length. 
F“ 0 U R T H 
FIFTH 
VESICLE 
Fig. 543.—Diagram of changes in fifth vesicle- 
view from above. 
The cavity of the myelon or spinal cord 
retains its original, cylindrical shape, and 
is called the central canal of the spinal cord. 
It is continuous at its cephalic end with 
the fourth ventricle. 
The preceding diagrams have been drawn 
as if all of the vesicles were upon the same 
plane, for the sake of simplicity ; but, during 
their synchronous development, a marked 
rOU R T H 
FIFTH VESICLE 
CAVITY OF 
SPINAL CORD 
Fig. 544.—Diagram of changes in fifth vesicle—view from 
left side. 
curve with a ventral concavity takes place 
at about the junction of the third ventricle 
and the aqueduct, and thus the long axis 
of the spinal cord is brought nearly to a 
right angle with the plane of the lateral 
ventricles. 
The description of the encephalic vesicles 
here given is not designed for a portrayal 
of the process which is discovered by em- 
bryological research, but is intended merely 
to present in a diagrammatic manner the 
main features of the results which are 
reached by the developmental process. 
Fig. 545.—Diagram of entire cavity of cere- 
bro-spinal axis—view from above. 
The shape and relative size of these different cavities, when fully formed, 
can be seen in Fig. 546, which represents a cast, made by filling them with a 
liquid material, which solidified on standing. The surrounding solid tissue 
being removed, we obtain a perfect cast of the general ventricular cavity, as the 
combined chambers and tubes of the encephalon are called. THE WALLS OF THE CEBEB 80-SPINAL AXIS. 
505 
The general ventricular cavity is moderately filled with a serous fluid, the 
cerebro-spinal, which mingles with the fluid occupying the serous space outside 
of the encephalic mass through a small hole, the foramen of Magendie (metapore), 
in the roof of the fourth ventricle. 
To illustrate the complexity and also the continuity of this cavity of the 
encephalon, imagine the shortest course 
which a small, aquatic insect must pur- 
sue in going from the apex of the 
middle horn of the lateral ventricle to 
the canal of the spinal cord, without 
leaving the cavity. First it would 
swim outward, and then successively 
backward, upward, inward, and for- 
ward, following the peculiar curves of 
the middle horn, before it could reach 
the body, the main hall, of the lateral 
ventricle. It would then pass forward 
and upward, for the floor of the ven- 
tricle slopes down from its front end. 
At the median side of the fore part of 
the ventricle, just at the beginning of 
the anterior horn, the little creature 
would work its way through the porta, 
a brief passage-way, which would let 
the traveller down into the third ven- 
tricle. Coursing backward through this 
deep crevice to its hind end, a narrow 
channel, the aqueduct, would be entered 
and traversed in a direction backward 
and downward. Emerging from this 
contracted passage, it would find itself 
in the shallow fourth ventricle, the long axis of which is somewhat backward, 
but more downward. Going from one end of this chamber to the other, it would 
arrive finally in the central canal of the spinal cord. 
Fig. 546.—Cast of general ventricular cavity- 
view from above. (Testut.) 
FORAMEN _ 
OF MONRO 
Fig. 547.—Cast of left lateral and third ventricles, from left side. (Testut.) 
THE WALLS OF THE CEREBRO-SPINAL AXIS 
Having now obtained an adequate idea of the cavity of the cerebro-spinal 
axis we proceed to study the walls which enclose this space. As has been said, 
they are composed of nervous tissue, which is lined with endyma and clothed 
with pia. The mass thus constituted may be conveniently considered in sections. 
Thus, we will take successively the walls of the lateral ventricles, of the third 
ventricle, of the aqueduct, of the fourth ventricle, and of the central canal of the 
spinal cord (Fig. 548). The several sections of the encephalon in their developed 
condition are commonly known by names other than those given to the primary 
vesicles, with a single exception. The walls of each lateral ventricle constitute a 506 
THE CEREBROSPINAL AXIS. 
cerebral hemisphere, the two hemispheres making the cerebrum; the region of the 
third ventricle is known as the thalamencephalon, on account of its walls consist- 
ing to a very large extent of two great bodies called thalami; the aqueduct is 
enclosed in a nervous mass, which is often known by its original name, mesen- 
cephalon, sometimes as the isthmus, from its forming a connecting bond between 
the parts before and those behind it, and, perhaps most frequently, as the crura 
cerebri (“ the legs of the cerebrum ”), from the stalk-like appearance of its 
ventral portion; and the fourth ventricle is surrounded by nervous masses so 
differentiated from each other that they are not designated by a single collective 
term, but are referred to as separate organs. Of these the principal are the 
cerebellum (“ the little cerebrum ” or “ little brain ”), the pons (“ the bridge ” or 
“ the bridge of Varolius ”), and the medulla oblongata (“ the oblong marrow”), 
also called by either of its names singly—preferably by the latter, as this gives 
no suggestion of the medulla 
spinalis (“ the spinal marrow ”), 
a name formerly much used 
instead of spinal cord, which 
is the final segment of the 
cerebro-spinal axis, and sur- 
rounds the central canal of 
the spinal cord. 
REGION OF THE 
LATERAL 
VENTRICLES 
REGION OF THE 
THIRD VENTRICLE 
REGION OF THE AQUEDUCT 
The relative proportion and 
disposition of the gray and 
white nervous matter are very 
different in the various parts. 
For example, in the cord the 
gray occupies a central posi- 
tion, while in the cerebrum 
the greater part of this kind 
of material is at the surface. 
In the encephalon we find also 
many collections of gray ner- 
vous tissue, which seem to 
casual observation isolated, 
and independent of the gray 
at the surface and of the 
rather regular, continuous, 
and orderly arranged gray sub- 
stance of the cord. The white 
nervous tissue is somewhat 
more easily understood, as we 
can trace a continuity in its 
REGION OF THE 
FOURTH VENTRICLE 
REGION OF THE 
CENTRAL CANAL OF 
THE SPINAL CORD 
Fig. 548.—Diagram to show the relations of the cavity to the 
principal divisions of the axis. 
mass for very considerable distances, indeed, practically from one extremity of 
the axis to the other. Beginning our inspection in the cord, we follow the fibres 
successively into and through the regions of the fourth ventricle, of the aqueduct, 
of the third ventricle, and last into the region of the lateral ventricles, where we 
find them ending in the gray matter of the very surface of the cerebrum. 
A Diagrammatic Description of the Brain. 
The relations of the primary segments of the encephalon in their fully devel- 
oped state are so complex that a diagrammatic presentation of the subject is a 
helpful introduction to its fuller study. 
The First Vesicle.—As would be expected from the great size and wide expan- 
sion of its cavity, the first vesicle attains a volume far in excess of that reached 
by any other ; indeed, so large does it become that its bulk surpasses that of all 
the others together, and it overlaps them to such an extent as to conceal them com- THE WALLS OF THE CEREBEO-SPINAL AXIS. 
507 
pletely in the view from above. Imagine it growing as the cavity has been repre- 
sented to spread out—its central part (the anla) increasing little, the lateral portions 
much—and suppose that in the median line the wall is relatively very thin, and 
almost everywhere else very thick. The result is that there is an immense mass on 
each side, the two separated by a deep fore-and-aft cleft, and held together by 
bands near the bottom of this dividing fissure. As in all other parts of the 
encephalon, there is substantially a bilateral symmetry in these structures; that 
is, the portion on one side is a reversed repetition of that on the opposite side. 
Seen from above each suggests by its form a half-globe; and, although the 
resemblance is not observed from other points of view, the name hemispheres is 
given to these cerebral masses. If the encephalon is cut in two exactly in the 
middle line, and an inspection is 
made of the left surface of the right 
half, we have such a view of the first 
and second vesicles as is shown in 
Fig. 549, only that the diagram, in- 
stead of displaying them in contact, 
as they lie in nature, represents the 
upper of the two segments as if nearly 
separated from the lower by a tilting 
up of its hind end and a correspond- 
ing depressing of its front, the pivotal 
point being the region of the porta 
(foramen of Monro), represented by a 
circle at the left of the label “ thala- 
mus” and a little above it. The 
red line indicates pia. Between the 
porta and the label is the aula (the 
median portion of the first vesicle), 
from the front and upper part of 
which the porta opens into the lateral 
ventricle. The anla and all above and in front of it is cerebrum, the develop- 
ment of the first vesicle. Observe that the pia is applied to the hemisphere and 
is reflected from it to the thalamus, which constitutes the main portion of the 
wall of the second vesicle. The part marked callosum is the cut surface of the 
great bond of union between the hemispheres. This body reaches far into the 
substance of the hemisphere, and forms the roof of the lateral ventricle. In 
the picture all above, before, and behind the callosum is free surface of the hemi- 
sphere, not cut by the median incision. A little below the callosum is an arched 
structure, labelled fornix, cut through by the incision. Between callosum above 
and fornix below is stretched a thin plate, the septum lucidum. Going down to 
the region of the second encephalic vesicle, we find that its cavity has been com- 
pletely exposed by the median cut, and its lateral wall, marked thalamus, displays 
a free surface ; but when we look for the cavity of the first vesicle, we find only 
the aula and the porta; that is to say, the front and upper part of the third ven- 
tricle, and the hole of communication between the third ventricle and the lateral 
ventricle, the last named chamber being shut from our sight by the septum 
lucidum. To get a view of the lateral ventricle our best plan is to slice off the 
mass of the hemisphere which lies over the callosum, and then to cut through the 
latter near the median line, removing as much of the structure as is necessary to 
expose the cavity beneath it. We shall then observe what is shown in Fig. 650, 
The right lateral ventricle has been unroofed by this removal and its floor is laid 
bare. This has a very uneven surface from the irregularity of the contour of 
the structures which form it. The intrusions of substance are due in one place 
to the thickening of the wall of the cavity, and in another to the infolding of the 
wall where it is rather thin. At the front part is an illustration of the former, 
the caudate nucleus bulging into the chamber in a region where there is a bulky 
THALAMUS 
CRUS 
CEREBELLUM 
PONS 
tOBLON-/ 
S GATA I 
Fig. 549.—Diagram to show the relations of the parts 
developed from the first vesicle to the parts developed 
from the second vesicle. The hemisphere is tilted for- 
ward. (F. H. G.) 508 
THE CEBEBBO-SPINAL AXIS. 
wall; and at the back part is an example of the latter kind, the calcar being a 
rounded ridge, which marks the location of a deep impression on the sloping 
area of the under surface of the hemisphere. 
In the floor of the ventricle are seen, in regular order from front to back, the 
gray caudate nucleus, around the fore part of which bends the shallow anterior 
cornu, while the mesial border of the mass is marked by a white ribbon-like 
band, the taenia semicircular is ; next and parallel to the last, a long, purplish body, 
the choroid plexus, composed of clumps of blood-vessels ; then a white structure, 
the fornix, whose outer margin is named fimbria; and, finally, the calcar, which 
forms the floor and mesial side of the posterior cornu. At the hind end of the 
fornix begins the middle cornu, which extends far down and forward, below the 
level of the parts seen by the removal of the callosum. Into it are prolonged 
Fig. 550.—Sketch of the right lateral ven- 
tricle from above, its roof having been cut 
away. (F. H. G.) 
Fig. 551.—Same as Fig. 550, except that the 
fornix has been folded back, exposing the 
velum interpositum. (F. H, G.) 
the caudate nucleus with its tsenia, the choroid plexus, and the fornix with its 
fimbria. In Fig. 549 the fornix is shown as the undermost of the nervous struct- 
ures concerned in forming the lateral ventricle in the median region, and its outer 
surface (which is underneath), like all external surfaces of the encephalon, is cov- 
ered with pia, the vascular membrane. If we cut away the fornix (as seen in 
Fig, 550), peeling it off carefully from the pia beneath it, we shall expose the 
attached surface of this membrane, and find that the object, which we have called 
choroid plexus, is the fringed and crumpled edge of this part of the pia, which has 
intruded itself into the lateral ventricle between the free border of the fornix and 
the free border of the caudate nucleus—that is, between the corpus fimbriatum 
and the tsenia semicircularis (Fig. 551). This intrusion is made possible by the 
disappearance of the nervous tissue along this line, and thus the pia covering the 
part and the endyma lining its cavity are brought into contact. The choroid plexus, 
like all the other parts of the wall of the ventricle, has its investment of endyma. THE CEBEBBUM. 
509 
The Second Vesicle.—The walls of the second encephalic vesicle, enclosing the 
most of the third ventricle, are strikingly unequal in their development. At 
the sides they become very thick, forming the masses called the thalami; in front 
and below the walls are very thin ; and at the top the nervous tissue disappears 
entirely, leaving the serous lining in contact with the vascular covering—the 
endyma and the pia thus constituting the roof of the cavity. 
In Fig. 549 the cerebral hemisphere is pictured as hinged at the region of the 
porta and canted forward, in order that it may be more easily regarded inde- 
pendently of the second encephalic segment. Now, let us replace the hemisphere 
in the position which it normally occupies, namely, resting upon the second seg- 
ment, the thalamencephalon (Fig. 552). The pia underlying the fornix and the 
pia overlying the thalamus are thus brought together, and in this way a double 
layer of vascular membrane is made to 
intervene between the bottom of the 
first encephalic segment and the top of 
the second. These layers fuse together 
and constitute the velum interpositum 
(“the interposed veil”). 
The first two encephalic segments 
have more in common than their con- 
nection in the region of the porta and 
the blending of the layers of pia which 
come between them. There is a con- 
tinuation into the hemisphere of great 
columns of nerve-tissue from the 
thalamencephalon, which receives them 
from the parts behind and below itself; 
and these will be described later. 
THA LAMUS 
CRUS 
PONS 
CEREBELLUM 
10BL0N- 
kGATAi 
The Third Vesicle.—Passing from 
the thalamencephalon we come to the 
mesencephalon, the region of the third 
encephalic vesicle, which contains the aqueduct. Here the walls are everywhere 
thickened, and, when viewed on their ventral aspect, look like two strong pillars, 
the crura cerebri; but their dorsal aspect presents four knobs, called corpora 
quadriqemina (“the four-twin bodies”). 
Fig. 552.—Diagram like Fig. 549, except that the 
hemispheres have been put back in their normal posi- 
tion. (F. H. G.) 
The Fourth Vesicle.—The ventral wall ot the fourth encephalic vesicle is 
thick, constituting the pons; the side walls, the pedunculi, are rather thin; and 
the true dorsal wall, the valvula, is very thin. But a large, solid mass, the cere- 
bellum, overhangs the rest of the segment, and to casual inspection conveys the 
idea of an enormous thickening of the dorsal wall. 
The Fifth Vesicle.—The fifth encephalic vesicle, the oblongata, is the part least 
altered from the form of the spinal cord, with which it is continuous. It looks 
as if it were split in the middle behind, and its upper part widely spread open. 
Stretching across the cavity from one of these spread edges to the other is a layer 
of endyma, covered by a thin layer of pia, without the intervention of any nerve- 
tissue, constituting the roof of this segment. 
The preceding diagrammatic presentation of the salient points in the structure 
of the encephalon will serve as a framework on which to build up more detailed 
information on the subject. 
The Surface of the Cerebrum 
THE CEREBRUM. 
The surface of each hemisphere of the cerebrum is composed of a layer of 
gray nervous tissue of variable thickness in different parts. The convex, exter- 
nar surface, the flat mesial surface, the irregular under surface—all present an 
outer stratum of cellular nerve-material, called the cortical layer, because it is a 510 
THE CEREBROSPINAL AXIS. 
covering, like the bark (cortex) of a tree. In the young foetus this cortex is 
smooth and uncreased (Fig. 553); but, as months go by, it becomes wrinkled, 
narrow depressions occurring all over it, and getting deeper and more numerous 
with its development (Fig. 554). These creases are infoldings of the cortex; 
and, consequently, the more numerous and the deeper they are the greater is the 
amount of the peripheral gray substance. They are called fissures, or sulci. To 
the uncritical eye they seem to be nearly or quite without system in their arrange- 
ment, and they give the cerebrum an appearance not inaptly compared to that of 
the mass of small intestines, which is seen when the abdomen is laid open and 
the omentum is lifted off. This coiled look has given the parts between the 
fissures the name of convolutions, or, 
better, gyri (Anglicized into u gyres ”). 
Though at first glance apparently dis- 
posed without order, the fissures and 
CEREBELLUM. 
•PONS 
OLFACTORY 
LOBE. 
"OLIVE. 
Fig. 553—Brain of six-months’ human embryo, natural 
size. (Kblliker.) 
Fig. 554.—Cerebrum of eight-months’ human 
embryo, left side. The insula is nearly covered 
in. (Testut.) 
gyri have been discovered to be for the most part so constant and regular that 
they have received names intended to be descriptive of their location or shape. 
They are similar on the two sides, but not identical, and are subject to considerable 
variations in different individuals. But before giving further consideration to 
the gyri and the fissures separating them, it is important to notice a few clefts 
which make larger divisions. 
The Longitudinal Fissure.—The two hemispheres are separated by the great 
longitudinal fissure. This goes through from top to bottom of the cerebrum in 
front and behind; but for the middle two-fourths or more of its antero-posterior 
length it is stopped when half-way down by the chief of the bands or commissures 
which connect the hemispheres, namely, the callosum (corpus callosum). All of 
the other fissures are found alike in each hemisphere, except the transverse, which 
is half in one hemisphere and half in the other. 
The Sylvian Fissure.—lnspecting the hemisphere from the side or from below, 
the most pronounced peculiarity of its form is seen to be due to the presence of 
a cleft, which starts near the centre of the base (at the anterior perforated space), 
and, going upward and backward, cuts so deeply as to mark off very conspicu- 
ously a large mass from the middle portion of the hemisphere at its lowest part. 
This fissure is the Sylvian (fissura Sylviana) (Figs. 554, 555, 559). The greatest 
part of the undivided fissure is plainly seen only on the base of the hemisphere, 
but its divisions are visible only from the side. A little of the fissure proper 
shows laterally, but it divides immediately into anterior and 'posterior limbs, the 
former subdividing into two short branches, ascending and horizontal. The poste- 
rior limb courses backward and a little upward, ending with a decidedly upward 
inclination at about two-thirds of the distance from the front to the back of the 
hemisphere, and half-way between summit and base. 
The Central Fissure.—ln the middle region of the lateral surface above the 
Sylvian fissure is the central fissure (Rolandic) (Fig. 555), extending in an 
undulating course from the longitudinal fissure forward and downward almost (or 
quite) to the Sylvian. It begins behind the half-way point between front and THE CEREBRUM. 
511 
back, and ends anteriorly to this plane, thus obliquely dividing the surface into 
approximately equal parts. 
The Parieto-occipital Fissure.—Far back on the upper margin of the hemi- 
sphere, as it slopes toward the base, is seen a notch, which marks the beginning 
of a fissure of the mesial surface, the parieto-occipital fissure, which will be 
described later. 
The Lobes on the External Surface (Fig. 555).—In these three fissures we have 
the basis for a division of the lateral surface into lobes ; and, although the 
division is rather artificial, and “ lobe ” is not an ideal name for the segments, it 
is necessary to have some means of designating the various parts, and this plan 
is convenient. The lobes visible on this convex surface are the frontal, the 
parietal, the occipital, and the temporal; but, though bearing the names of certain 
cranial bones, the limits of the lobes do not coincide with those of the osseous 
structures nearest which each respectively lies and from which it gets its name. 
If a line is drawn from the parieto-occipital fissure downward and forward to a 
point on the lower border beneath the rear end of the Sylvian fissure, usually 
marked by a notch, the pre-occipital, and another line in prolongation of the 
nearly horizontal part of the Sylvian fissure is made to touch the first one a little 
above its middle, the delimitation of the lobes is effected. Behind the parieto- 
PARIETO- 
OCCIPITAL 
FISSURE 
Fig. 555.—The lobes of the convex surface of the hemisphere, left side. 
occipital line is the occipital lobe ; in front of this and beneath the Sylvian fissure 
and its extension is the temporal lobe (temporo-sphenoidal); in front of the central 
fissnre is the frontal lobe; and the residue, the area bounded in front by the 
central fissure, below by the Sylvian, behind by the parieto-occipital and its 
imaginary prolongation, and above by the longitudinal fissure, is the parietal lobe. 
The Insula.—If the lower and front part of the parietal lobe and the lower 
and back part of the frontal lobe are lifted away from the Sylvian fissure, and 
the adjacent part of the temporal lobe is pressed down, there is brought into view 
a fifth lobe, which, from its situation, is called the central lobe, but is more com- 
monly known as the insula, (“the island”) or the island of Reil (Fig. 556). 
Until foetal life is half completed this lobe is distinctly superficial; but then its 
immediate neighbors increase so rapidly in size as to outstrip the insula in the 
race of growth—the parietal folds down, the frontal bulges back, the temporal 
crowds up from below—and among them it gets completely covered in ; and in 
this process the Sylvian fissure is formed, the portion between the frontal and 
temporal lobes being the main fissure, that between parietal and temporal being 
the posterior limb, and that within the frontal the anterior limb. Morpho- 
logically the insula is the oldest lobe, and it stands, as will soon be shown, in 512 
THE CEREBROSPINAL AXIS. 
closer relation than any other to the great ganglia at the base of the hemisphere. 
The insula is sometimes called gyri operti (“ the covered gyres ”); and the parts 
of the frontal and parietal lobes which overlap the insula are known as the 
operculum (“ the cover ”). 
The Lobes of the Mesial and Tentorial Surfaces.—The mesial surface of the 
hemisphere cannot be seen plainly without dividing the encephalon in the middle 
line, and removing the hemispheres from each other ; and the surface which con- 
Fig. 556.—The left insula, the overlapping parts of the hemisphere having been removed. The numerals 
specify the gyri. (Dalton). 
tinues the mesial downward (called the tentorial surface, on account of its resting 
in part upon the tentorium) is brought into view from the middle line by the 
removal of the crus and all below it. This dissection exposes a number of 
objects huddled together in the centre of the field, of which the largest, highest, 
and most conspicuous is the callosum, already mentioned 
as the great bond of union between the hemispheres. 
This displays a broad, cut surface, which forms a flat- 
tened arch from the front to the back of this mid region, 
and under the arch are gathered many structures, which, 
being internal, will be passed by until the study of the 
periphery is completed. When we look directly upon 
the flat, mesial surface of the hemisphere, the tentorial 
surface, into which the mesial runs at its lower border, 
slopes away from us to the lower margin of the convex, 
external surface, as is shown by Fig. 557. Thus, when 
viewed from the median line the tentorial surface is a 
p-ood deal foreshortened. 
Fig. 557.—Outline of coro- 
nal section of hemisphere, 
showing slope of tentorial 
surface. 
On the mesial surface (Fig. 558) are parts of two fissures already mentioned 
as appearing on the convex surface : the central, the upper end of which notches 
the sharp border more than half-way back; and the parieto-ocdpital, which, from 
its small beginning on the convexity of the hemisphere, is continued over the 
border, and then downward and forward, joining the calcarine at an acute angle. 
The calcarine fissure (from calcar, “a spur”) runs from near the rather pointed 
hind end of the hemisphere upward and forward, and just beyond its middle, at 
the point where it receives the parieto-occipital, bends downward, and terminates 
beneath the rear end of the callosum. Encircling the callosum is a fissure, 
called the callosal. Beginning below the front end of the callosum is a fissure, which 
runs in a curve nearly concentric with that of the callosal and also with that of 
the margin of the hemisphere, until a point above the hind end of the callosum 
is reached, at which the fissure turns, and runs upward and backward to the 
upper border. Its situation gives it the name calloso-marginal fissure. Coursing 
in the general direction of the body of this fissure, between it and the parieto- THE CEREBRUM. 
513 
occipital, is frequently an irregular, somewhat broken fissure, the precuneal or 
subparietal; and running nearly horizontally in the midst of the sloping tentorial 
Fig. 558.—The lobes of the mesial and tentorial surfaces of the left hemisphere. 
surface is the collateral fissure. The area between the calloso-marginal fissure and 
the upper edge of the hemisphere belongs to the frontal lobe ; that bounded by the 
upturned end of the calloso-marginal fissure, the free border, the parieto-occipital, 
and the precuneal fissures is a part of the 
parietal; that between the parieto-occipital 
and the calcarine fissures is a portion of the 
occipital; and all below the level of the 
anterior limb of the calcarine is often as- 
signed to the temporal. But the part of the 
temporal mass which is anterior to the tip of 
the calcarine fissure and above the collateral 
fissure is better associated with the area 
which is bounded peripherally by the calloso- 
marginal, precuneal, and calcarine fissures, 
to which (with several other structures, which 
need not be mentioned at present) are given 
the names of limbic lobe and falciform lobe, 
the former from its forming a border for the 
callosum, the latter because the sweep of its 
curve is suggestive of a sickle. 
If we look at the hemisphere from below, 
we see parts of the temporal, limbic, frontal, 
and occipital lobes (Fig, 559). 
We have now before us the primary 
superficial divisions of the hemisphere, 
namely, the insula, the frontal lobe, the 
parietal lobe, the occipital lobe, the temporal 
lobe, and the limbic lobe, and are prepared to 
consider the subdivisions of each of them. 
These secondary parts are gyri, and are sepa- 
rated from each other by fissures. 
G-yri of the Insula.—The insula or central 
lobe has five gyri, which radiate from the 
narrow lower part, like the folds of a fan 
from its handle (Fig. 556). They are separated from each other by simple fissures, 
Fig. 559.—The lobes of the left hemisphere, 
seen from below. 514 
THE CEREBROSPINAL AXIS. 
and the lobe is margined at the sides and top by the circular fissure (fissura limi- 
tans insulae). 
Parieto-Occip. 
V Fissure 
Sylvian Fis." 
Preoccip. Notch 
Pig.s6o—The gyri and fissures of the external lobes of the left hemisphere 
Frontal Gyri (Figs. 560—563).—On the convex surface of the frontal lobe are 
three fissures, two of which, the superior and inferior frontal, have a general fore- 
Fig. 561.—The hemispheres viewed from above. The fissures are labelled on the left side, the gyri on the right. 
and-aft direction, and the third, the precentral (commonly broken), is substantially 
parallel with the central fissure. By these fissures the lobe is divided into four THE CEREBRUM. 
515 
gyri; the first (superior) frontal, between the longitudinal fissure and the superior 
frontal; the second (middle) frontal, between the superior and inferior frontal 
fissures; the third (inferior) frontal, beneath the inferior frontal fissure, capping 
the anterior limb of the Sylvian fissure; and the precentral (anterior central, 
ascending frontal) between the precentral and central fissures. 
On the under sufface the frontal lobe has two principal fissures. The first 
runs parallel with the great longitudinal and close to it, and is called the olfactory 
fissure from its giving lodgement to the olfactory nerve and its bulb. The other, 
the supra-orbital fissure, is very irregular, generally starting near the Sylvian 
fissure, coursing forward and then outward, and sending offshoots in various 
directions. The narrow gyrus between the longitudinal and the olfactory fissures 
is a continuation of the first frontal gyrus of the convex surface, the gyrus between 
Fig. 562.—The hemispheres viewed from helow. The gyri of the right hemisphere are labelled, the fissures 
of the left. 
this and the supra-orbital fissure is continuous with the second frontal of the con- 
vexity, and the residue of the surface is continuous with the third frontal. 
On the mesial surface the gyrus which begins under the front end of the 
callosum, and is bounded at first above, then behind, and then below by the 
calloso-marginal fissure, is continuous with the first frontal over the edge of the 
great longitudinal fissure. It is called the marginal gyrus from its situation. It 
really overlaps by a little the parietal region of the convex surface, and the cen- 
tral fissure appears as a notch in its hindmost part. A vertical fissure marks off 
a squarish area in this region, called the paracentral gyrus, because it is continu- 
ous with the gyri before and behind the central fissure of the convexity. 
Parietal Gyri (Figs. 560—563).—The parietal lobe does not appear on the 
under surface. On the outer surface is the intraparieial fissure, which starts near 
the Sylvian, passes up a short distance, and then swings back and runs almost 516 
THE CEREBROSPINAL AXIS. 
parallel with the longitudinal. As has already been seen, the upturned end of the 
Sylvian fissure is within the parietal lobe. The gyri are the post-central (poste- 
rior central, ascending parietal) just behind the central fissure; the superior 
parietal, above the intraparietal fissure; the supra-margined, above the hind part 
of the Sylvian fissure and arching over its end; and the angular, which occupies 
the remainder of the area, and is at the lower, rear corner of the lobe. 
Continuous with the lateral surface over the edge of the longitudinal fissure 
is the mesial surface of the parietal lobe; but it has less width than the external 
surface, inasmuch as the calloso-marginal fissure does not end coincidently with the 
central, but a little to its rear, and the difference makes an addition to the frontal 
lobe by subtraction from the expected domain of the parietal. The mesial 
parietal gyri make a four-sided area, called the precuneus, from its relation to 
the wedge-shaped occipital gyrus adjoining, and u quadrate lobule ” from its 
squarish shape. 
Occipital Gyri (Figs. 560-563).—The convex area of the occipital lobe is con- 
ventionally divided into three gyri by two fissures; but these are very inconstant 
and irregular, and the typical arrangement is apparently not yet discovered— 
Fig. 563.—The mesial and tentorial surfaces of the left hemisphere, showing the gyri. The fissures have, 
been named in Fig. 558. 
certainly it is not agreed upon by the anatomists of the largest observation. The 
triangular form of the mesial occipital surface has led to its being named cuneus 
(“ wedge ”). It is continuous with the convex surface over the edge of the longi- 
tudinal fissure. 
Temporal Gyri (Figs. 560, 562, 563).—The temporal (temporo-sphenoidal) 
lobe is marked by three fissures, which have a general fore-and-aft direction, two 
of them appearing on the lateral surface, and being called respectively the first or 
superior temporal or parallel fissure (the latter name from its relation to the pos- 
terior limb of the Sylvian fissure) and the second or inferior temporal fissure. The 
third temporal fissure is largely on the line between the lateral and under surfaces. 
The front half of the collateral fissure separates the temporal from the limbic 
lobe, and its rear half lies in the hind part of the temporal. The temporal gyri 
are the first (superior), the second (middle), and the third (inferior) on the outer 
surface, and, on the base or tentorial surface, the subcollateral, which is beneath 
the collateral fissure, and the subcalcarine, which lies between the calcarine fissure 
and the rear of the collateral. 
Limbic Gyri (Figs. 562, 563).—The limbic lobe consists primarily of the cal- 
losal gyrus, which arches over the callosum, and the continuation of this which 
courses forward on top of the temporal lobe, and is known as the hippocampal, or THE CEREBRUM. 
517 
uncinate, gyrus. The first name of the latter gyrus comes from its relation to a 
structure which is seen in the middle horn of the lateral ventricle ; the second 
refers to its hook-like distal end. But, in addition, there are included in this lobe 
other parts, dissimilar in appearance and errant from the structural character, 
which we associate with the idea of a lobe of the brain. They are the lateral 
half of the septum lucidum, the dentate gyrus, the fornix, the striae longitudinales 
of the callosum, and the peduncles of the callosum, and have been grouped with 
the great gyri just named on grounds of morphology and embryology, rather than 
from considerations based upon adult structure. 
In the limbic lobe are the callosal fissure, previously described, and the hippo- 
campal fissure, which marks the upper boundary of the hippocampal gyrus, 
Fig. 564.—Diagram to show position which fissures of mesial and tentorial surfaces would occupy if pro 
jected in a horizontal plane sidewise to the outer surface. (F. H. G.) 
extending from the back of the splenium of the callosum into the embrace of the 
hook of the gyrus. Seemingly lodged in the hippocampal fissure is a long slender 
roll of gray substance, notched upon its exposed surface, and called the dentate 
gyrus (fascia dentata). It begins behind the splenium, receiving here the striae 
longitudinales of the callosum, runs to the end of the hippocampal fissure, and 
terminates by bending up over the uncus. Above it lies the fimbria, and between 
the two is a shallow cleft, called the fimbrio-dentate fissure. 
Relation of the Principal Lobes to the Parts of the Lateral Ventricle. 
The cavity of the frontal lobe is the anterior horn ; that of the parietal lobe 
is the body ; that of the occipital lobe is the posterior horn ; and that of the tem- 
poral lobe is the middle horn (Fig. 565). 
Situation of the Lobes in the Cranium. 
The frontal rests upon the orbital plates of the frontal bone ; the temporal 
occupies the middle fossa of the base of the skull; the occipital is supported upon 
the tentorium, being thus separated from the cerebellum, which fills the posterior 
fossa; and the parietal is held up by the subjacent cerebral structures, and is 
covered by the sides and vertex of the skull. 
Almost every part of the cortex of one hemisphere is connected with the cor- 
responding part of the other hemisphere by nerve-fibres. In and near the median 
The Callosum. 518 
THE CEREBROSPINAL AXIS. 
line of the cerebrum all of these fibres are compressed vertically and, to a less 
degree, antero-posteriorly into a solid mass. Consequently the fibres seem to 
radiate from each side of this condensed body—going out, up, down, forward, 
Fig. 565.—Diagram to show planes of lateral ventricle projected upon the outer surface of the hemisphere, 
as if the ventricle were filled with opaque pigment, and were seen through transparent wall of hemisphere. 
(F. H. G.) 
backward—to terminate in the gray matter at the periphery of the hemisphere 
(Figs. 566, 567). The mass (with a slight addition, presently to be described) is 
the corpus callosum (“ the hard body ”), called, also, 
merely callosum. The middle of it can be seen by 
drawing the upper portions of the hemispheres apart, 
so as to widen the great longitudinal fissure, and 
looking directly downward into this enlarged cleft 
Fig. 566.—Diagram of coronal sec- 
tion of cerebrum to show course of 
fibres of callosum. (Testut.) 
Fig. 567.—Diagram of horizontal 
section of cerebrum to show course of 
fibres of callosum. (Testut.) 
(Fig. 561). It presents a free surface on top, in front, and behind; but its 
shape and size are not appreciated until sections of the cerebrum are made in 
various directions. A vertical median division of the cerebrum shows a cut 
surface of the callosum, which reveals its form and extent from before backward 
(Fig. 568). It is seen to be a long, thick, irregularly flattened arch. Its front 
end is curled back underneath, and is called the genu (“ knee This thins out 
rapidly to an edge, the rostrum (“ beak ”), which is connected with the front part 
of the wall of the third ventricle by a delicate plate, the basal white commissure, 
or copula. The hind end, also, is rounded, its lower part being folded sharply 
forward, and is named the splenium (“bandage”). The portion between the genu 
and splenium is the body. If the cerebral tissues which overlie the callosum at 
the sides are cut away, it is found to be depressed along the middle line, and to THE CEREBRUM. 
519 
rise at the sides into the substance of the cerebrum (Fig. 569). The part of the 
Fig. 568.—Parts of mesial and tentorial surfaces of left hemisphere, showing callosum in sagittal section 
with many of its relations, a.c., anterior commissure ; alb., corpus albicans ; chi., chiasma; hypoph., hypoph- 
ysis; p., porta. (Modified from Testut.) 
callosum which curves forward on each side from the genu into the frontal lobe 
is called the forceps anterior or minor; and that which projects backward in a 
SYLVIAN. 
FISSURE 
SYLVIAN 
FISSURE 
Fig. 569—Upper surface of callosum, the overlying parts cut away. (Testut.) 
corresponding manner from each side of the splenium into the occipital lobe is 
known as the forceps posterior or major. Between the two forceps of each side 520 
THE CEREBROSPINAL AXIS. 
is a plate, which extends laterally into the temporal lobe, and is named the tapetum 
(“ mat”). 
On the upper free surface of the callosum some small bundles of fibres run 
lengthwise, and from this fact are called strice longitudinales (“ longitudinal 
stripes ”). They are in two sets on each side : a median, which lies close to the 
central depression; and a lateral, which is lodged in the callosal fissure, and is 
named tenia tecta (“ the concealed band ”), from its being covered up by the cal- 
losal gyrus. These bundles diverge in front along the inner boundary of the 
anterior perforated spaces, constituting the peduncles of the callosum, and are lost 
in the beginning of the Sylvian fissures. Behind they are traced into the back 
part of the hippocampal gyri. 
The fore-and-aft median measurement of the callosum is about five inches; its 
depth behind is nearly an inch, in front a little less. 
Fig. 570.—Diagram showing association-fibres of the hemisphere. (Testut.) 
The callosum forms the roof of the lateral ventricles, the tapetum covering in 
the posterior and middle horns. 
As the fibres of the callosum radiate to the cortex of the hemisphere, they 
interlace with those of The great columns ascending from the lower levels of the 
encephalon, and the two sets together constitute the chief bulk of the white sub- 
stance of the cerebrum. But there are also unnumbered bundles of fibres which 
connect near or remote gyri, as shown in Fig. 570. They are called association 
fibres. 
The Fornix (Figs. 571, 568, 572). 
In the median section of the encephalon there is seen below the callosum and 
attached to the back part of its lower surface a white body, which curves forward 
and downward, then downward, and then downward and backward to the under 
surface of the brain, where it seems to double upon itself in a tight loop, and 
then to course upward, backward, and a little outward to the thalamus, in which 
it is lost. This is a part of the fornix (“ arch ”), the remainder requiring another 
dissection for its exhibition. The callosum and all the structures above it having 
been removed, we can look down upon the floor of the lateral ventricles, and thus 
obtain a view of the upper surface of the fornix. It is now perceived to be 
bilaterally symmetrical. A little of the anterior, descending part is seen in this 
view, and just behind this the two halves are joined together for a short distance. 
Traced backward, however, the bands diverge, swing off-to the sides, and dis- 
appear at the upper ends of the middle horns of the ventricles. Cutting away the 
roof of these cornua, we find the bands following the curve of these cavities, and THE CEREBRUM. 
521 
partly spreading out over the hippocampus, partly continued on the inner wall of 
the horn. Between those parts of the diverging bands which lie in the bodies of 
the ventricles is stretched a thin layer of fibres. The part of the fornix which 
T/ENIA 
~S E M ICI RCULA R IS 
Fig. 571.—F100r of the lateral ventricles. On the left side the vein of the corpus striatum is lifted up. The 
director is in the right porta. Dotted outlines indicate the position of the posterior cornua. (Testut.) 
results from the direct union of the two lateral bundles is its body; the portion in 
front of the body is the anterior pillars; the diverging bands behind the body are 
the posterior pillars; the little triangular sheet connecting the posterior pillars is 
Fig. 572,—Diagram of thalamus, fornix, and hippocampal gyrus of right side, seen from middle line. 1, 
anterior tubercle of thalamus; 2, bundle of Vicq d’Azyr; S, corpus albicans; U, anterior pillar of fornix; 5, 
anterior commissure; 6, body of fornix; 7, posterior pillar of fornix; 8, fimbria ; 9, dentate gyrus. (Dalton.) 
the lyra; the outer free edge of the body and posterior pillar is the fimbria, or 
corpus fimbriatum (“ fringed body ”); the little knobs produced by the abrupt 
reversal of direction of the anterior pillars at the base of the brain are the cor- 522 
THE CEREBROSPINAL AXIS. 
pora albicantia (“ whitish bodies”), otherwise called corpora mammillaria (a teat- 
like bodies ”). The upward-passing cord from the corpus albicans of each side to 
the corresponding thalamus is known as the bundle of Vicq-d’Azyr. 
Thus it appears that the fornix is a fore-and-aft commissure, pursuing a cir- 
cuitous course from the base of the brain in the region of the thalami to the 
descending horns of the lateral ventricles. Each lateral half of the fornix is 
principally devoted to the association of the parts on its own side; but each also 
has, through the lyra, a connection with the corresponding organs on the opposite 
side. 
The Anterior Commissure (Fig. 573). 
Directly in front of the anterior pillars of the fornix a rope-like bundle of 
nerve-fibres runs across from the front part of one temporal lobe to the correspond- 
ing part upon the opposite side. It describes in its course a large curve with its 
Interior pillars 
' OF FORNIX 
Fig. 573.—Anterior commissure, left half, viewed from above. (Testut.) 
convexity forward and a little upward. It passes through the lenticular nuclei, 
and finally spreads out in the temporal lobes. This is the anterior commissure. 
The Septum Lucidum. 
Occupying the space between the under surface of the callosum and the upper 
surface of the fornix is a structure, called the septum lucidum (“ the clear parti- 
tion”) (Fig. 568). It forms the dividing wall between the lateral ventricles. It 
consists of two layers of nervous tissue, enclosing a small, perfectly closed cavity, 
a mere crevice, which has no communication with any of the chambers of the 
encephalon. This hollow space is formed by a process of vacuolation, which 
means substantially that the middle part of the single thick plate, of which the 
septum originally consisted, was withdrawn by gradual absorption, leaving in its 
stead a chink, which is the cavity of the septum lucidum (Fig. 577). This space 
is occupied by a little serous fluid. The Avail next to the cavity is gray, but is 
white on the outside—that is, next to the lateral ventricle. 
The Ganglia of the Hemisphere. 
Embedded in the substance of the hemisphere are several masses of gray mat- 
ter, which seem upon casual inspection to be detached collections, quite independ- 
ent of the cortex. On careful examination, however, they are found to be con- 
tinuous with the superficial gray substance, and even with each other. They are THE CEREBRUM. 
523 
the caudate nucleus, lenticular nucleus, claustrum, and amygdaloid nucleus, or 
amygdala (Fig. 574). 
The caudate nucleus and the lenticular nucleus have commonly been described 
Fig. 574.—Diagram to show the continuity of the gray of the basal ganglia of the cerebral hemispheres, the 
cortex, and the lower segments of the cerebro-spinal axis. (F. H. G.) 
as parts of a single body, called corpus striatum {“ striped body ”), on account of 
the peculiar, striped appearance of the surfaces resulting from its section ; but 
description is facilitated by treating them as independent structures. The caudate 
Fig. 575.—Right lateral ventricle opened from its mesial side. A, amygdala. C, caudate nucleus. S, sur- 
cingle. V. cavity of ventricle. 1, parieto-occipital fissure. 2, calcarine fissure. (Dalton.) 
nucleus presents a free surface in the floor of the lateral ventricle, and hence is 
sometimes spoken of as the intraventricular portion of the corpus striatum ; the 
lenticular nucleus does not appear at all in the ventricle, and, consequently, is THE GEREBII OS PIN A L AXIS. 
occasionally referred to as the extraventricular portion of the corpus striatum. 
The claustrum is a plate of gray substance, embedded between the lenticular 
nucleus and the insula. The amygdaloid nucleus is a collection of gray matter 
near the apex of the temporal lobe. 
The caudate (“ tailed ”) nucleus protrudes into the cavity of the lateral ven- 
tricle at the fore part of the floor, the anterior horn curving forward and outward 
around its most prominent portion (Fig. 576). The front end is rounded, and faces 
upward, forward, and inward. From this large beginning the nucleus diminishes 
in size as it is traced backward, and hence the most conspicuous part of it is pear- 
shaped. But the stem of the pear—the tail or cauda, which gives its name to 
The Caudate Nucleus. 
Fig. 576.—Lateral and third ventricles from above. The fornix and velum interpositum have been 
removed. EPL, epiphysis. M. C., middle commissure. P. C., posterior commissure. (Testut.) 
the nucleus—stretches backward and outward as a slender prolongation through 
the body of the ventricle to the rear end, and thence in a sweeping curve into 
the middle horn and even to its extremity, clinging to the roof of the cornu (Fig. 
575). It thus describes almost a circle, the tip of it reaching a point nearly 
underneath the blunt beginning. As it embraces in its loop a considerable mass 
of brain-tissue, it has been named the surcingle. It is not of regular outline, but 
is alternately and unevenly constricted and enlarged (Fig. 578). The caudate 
nucleus ends in the amygdala at the front end of the temporal lobe. 
Along the inner border of the caudate nucleus is a band of fibres, which may 
fairly be regarded as its proper edge. It is called the taenia semicircularis (“ the 
half-circle ribbon”) (Figs. 576, 550). It accompanies the tail of the nucleus in 
the roof of the middle horn even to the amygdala. In the body of the ventricle 
it is covered by the vein of the corpus striatum. THE CEBEBB UM. 
525 
The Lenticular Nucleus. 
In order to obtain an adequate view of the lenticular (“ lens-like ”) nucleus, 
it is necessary to make horizontal and vertical sections through that part of the 
substance of the hemisphere in which it is located. By such means we learn that 
this gray mass lies at the outer side of the caudate nucleus, but is for the most 
part separated from it by a 
thick plate of white nervous 
tissue, the internal capsule. Its 
shape is that of an irregular, 
three-sided pyramid (Figs. 577, 
578). It is divided into three 
unequal portions by two layers 
of white matter, the internal 
and external medullary laminae. 
The outer portion is the larg- 
est, is of a deep, red hue, is 
streaked at its inner part with 
nearly horizontal, white lines, 
and is called the putamen 
(“husk”). The other por- 
tions are yellowish-gray, and 
together constitute the globus 
pallidus (“ the pale sphere ”). 
The lenticular nucleus is 
not entirely embedded in the 
brain substance : a portion of 
it is at the surface of the base 
of the cerebrum, at the outer 
side of the chiasma and behind 
the roots of the olfactory lobe, 
in the anterior perforated space. 
The internal capsule does not 
wholly separate the lenticular 
and caudate nuclei, the two 
masses being united below and 
in front of it, and being 
further connected by thin cords of gray matter, which cross the capsule. The 
claustrum is fused with the lenticular nucleus at the anterior perforated space ; 
the amygdala is united with its hind and lower part; and through the amygdala 
the nucleus is continuous with the cortex of the hemisphere. From these facts 
concerning the association of the gray masses of the hemisphere, we see that 
there is good reason for regarding them as thickenings of the peripheral gray 
cnUc+n nm 
PILLARS 
OF FORNIX 
CLAUS- 
TRUM 
POSTERIOR PILLAR 
OF FORNIX 
Fig. 577.—Horizontal section of left hemisphere through the basal 
ganglia, viewed from above. C. N., caudate nucleus. (Testut.) 
The Anterior Perforated Space is situated at the base of the brain at the point 
from which the Sylvian fissure starts. The optic tract lies obliquely behind it, 
mesially it is continuous with the lamina cinerea, in front is the orbital surface 
of the frontal lobe. It is marked by numerous holes, through which pass blood- 
vessels to the lenticular nucleus. Fig. 562 shows it on each side of the chiasm. 
The Claustrum (Fig. 577). 
Just outside of the lenticular nucleus is a thick stratum of white tissue, called 
the external capsule, which will be described later. Between this external cap- 
sule and the white substance which furnishes the backing of the gray of the 
insula is a thin lamina of gray tissue, called the claustrum (“barrier”). Its sur- 
faces are directed respectively toward the insula and the lenticular nucleus. In 526 
THE CEREBROSPINAL AXIS. 
horizontal or vertical section its outline is undulating. The adherent tissues being 
dissected away, it is seen to be of triangular shape, with its apex above; and 
its base, which is its thickest part, is found to reach to the surface of the brain 
at the anterior perforated space, where it is united to the lenticular nucleus. 
Fig. 578.—Longitudinal section through the entire right caudate nucleus, viewed from mid line. The plane of 
the section is not perpendicular, but has followed the surcingle outward. C, caudate nucleus. CC, front part 
of callosum. F, frontal lobe. O, occipital lobe. T, temporal lobe. S, surcingle. 1, 2, inner and middle zones 
of lenticular nucleus. 3, internal capsule. Observe the continuity of the gray substance. (Dalton.) 
The olfactory lobes, the optic tracts, and the chiasma will be considered in con- 
nection with the cranial nerves. 
The Amygdaloid Nucleus (Figs. 581, 586, 575). 
This ganglion, otherwise called amygdala, is a mass at the tip of the temporal 
lobe, due to a thickening of the cortex of this region. It is of sufficient size to 
cause a protrusion into the roof of the middle horn of the lateral ventricle, at 
whose distal end it receives the extremity of the surcingle. It is continuous in 
front and above with the lenticular nucleus. 
The Velum Interpositum. 
Although it is a part of the parietes of the third ventricle, the velum inter- 
positum (“ interposed veil ”) requires description here because its fringed edges, 
the choroid plexuses, appear in the floor of the lateral ventricles, and cannot be 
understood except in connection with the velum. It will be recalled (Figs. 549, 
552) that the pia of the under side of the developing first brain-vesicle is brought 
by the backward and downward growth of that segment directly in contact with 
the pia of the upper surface of the second brain-vesicle. The combination of 
the two layers of pia constitutes the velum interpositum—the veil placed between 
the prosencephalon and the thalamencephalon. It lies just beneath the part of 
the fornix which appears in the bodies of the lateral ventricles, and just above 
the cavity of the third ventricle, resting at the sides upon the upper surfaces of the 
thalami. In the floor of each lateral ventricle, between the fimbria, which makes the 
edge of the fornix, and the taenia semicircnlaris, which margins the caudate nucleus, 
is a narrow strip of the parietes of the first encephalic vesicle in which there is an 
entire absence of nervous tissue, and, consequently, the wall of the vesicle in this 
area consists merely of endyma and pia. The fimbria and taenia are prolonged from 
the body of the lateral ventricle into its middle horn ; and the wall between them 
here is like that between them in the body of the ventricle—merely pia and endyma 
in close contact, the nervous tissue which once existed in this narrow area having THE CEREBRUM. 
527 
disappeared. The highly vascular pia, wherever it covers nervous tissue, sends 
branches of its vessels into the surface layers of this tissue; but along this line, 
which extends from the porta (foramen of Monro) to the tip of the middle horn, 
the pia lies against no such resistant material, being applied closely to the delicate 
endyma. Its branches, becoming dilated and 
prolonged, push the filmy serous membrane in- 
ward, so that an irregular, clumpy mass of vessels, 
covered everywhere with endyma, encroaches 
upon the space originally devoted to the ventric- 
ular cavity. This vascular structure is called the 
choroid plexus (“leather-like network”) (Fig. 
571). It is convenient to speak of the “intru- 
sion ” of the choroid plexus into the ventricular 
cavity; but as the cavity is limited by the 
endyma, and no breach is made in this membrane, 
the expression is not strictly correct, the fact 
being that the wall of the cavity is bent inward, 
and the contained space is by so much diminished. 
All of the choroid plexuses are explained in the 
same way. It is to be noted that, while the 
choroid plexus of the body of the lateral ventricle 
is derived from the velum, the choroid plexus of the posterior horn is derived 
from the pia which clothes the limbic lobe. 
The diagram (Fig. 580) will aid one in understanding this. In it the velum 
is shown as a triangle marked with transverse red lines; the choroid plexuses are 
in solid red ; the taeniae semicirculares are in blue ; and the outline of the fornix 
and fimbriae is indicated by broken lines. We are looking down upon these 
objects. On the right of the diagram the taenia and fimbria, with the intervening 
choroid plexus, are represented as straightened out, as if the temporal lobe and 
Fig. 579.—Diagram of transverse 
section of axis where a portion of the 
nervous wall has disappeared, allowing 
pia and endyma to come together. 
Fig. 580—Diagram to show relations of tenia,fimbria, and choroid plexus in body of lateral ventricle and 
in middle horn. On the right side the parts are straightened out, on the left they are curved in their natural 
shape. (F. H. G.) 
the adjacent part of the limbic lobe had been stretched backward. On the left 
the parts are shown with the curve naturally described by the middle horn. In 
making the curve the parallelism between the two nervous bands is substantially THE CEREBROSPINAL AXIS. 
maintained, but the taenia gets above the fimbria. The middle horn is much 
nearer to the mesial than to the outer surface of the temporal lobe, so near, in 
fact, that the fimbria is covered with pia. In the region of the velum the 
choroid plexus is formed by the pia which makes the velum ; beyond the hind 
edge of the velum the plexus is made from the pia immediately on the surface 
of the brain. 
The crevice through which the invagination of the pia is effected is called the 
transverse fissure, or the choroid, fissure; and it extends from the porta (foramen 
of Monro) nearly to the distal end of the middle horn on each side. 
In the posterior horn of the lateral ventricle (Fig. 581) the inner wall, which 
slopes outward toward the floor, presents a prominent protrusion, caused by the 
pushing in of the entire wall of the cavity at this point in correspondence with 
the depression upon the tentorial surface of the hemisphere, which we know as 
CORPUS ALBICANS-# 
CORP. GENIC. EXT- 
CORP. GENIC. INT- 
DENTATE 
—GYRUS 
* PILLAR OF FORNIX 
POSTERIOR PILLAR— 
OF FORNIX 
Fig. 581.—Horizontal section of left hemisphere, opening the middle horn of the lateral ventricle. The 
upper segment, containing the roof of the horn, has been turned off to the left. (Testut.) 
the calcarine fissure. The elevation is well called the calcar (“spur”), although 
a less suggestive and helpful name, hippocampus minor (“ the smaller sea-horse ”) 
is more commonly used. Just above the calcar is another prominence, the bulb, 
produced by the posterior forceps of the callosum. The roof of this cornu, as stated 
previously, is furnished by the tapetum of the callosum. Finally, the floor is 
triangular, has a convex surface, owing to the intrusion of the wall caused by the 
formation of the collateral fissure, and is called the eminentia collateralis. The 
posterior horn gets its peculiar curve from the intrusion of the parieto-occipital 
fissure on the mesial surface of the hemisphere (Fig. 558). 
In the middle horn of the lateral ventricle the parietes are the internal (mesial) 
wall, the floor, and the roof (Figs. 575, 578, 581, 582). The inner wall swells out- 
ward, so that it is seen in large part in a view from above; the floor is rounded THE CEREBRUM. 
529 
up in the middle like a turnpiked road ; and the roof, which presents the broadest 
surface of this prismatic cavity, is slightly arched. The bulging of the mesial 
wall corresponds to the depression in the cortex, which is named hippocampal 
fissure, and itself is called the hippocampus (“sea-horse”)—sometimes major 
(“ the greater ”) being added. This peculiar elevation widens as it extends 
toward the apex of the horn, and terminates in a blunt indented end, called the 
pes hippocampi (“ the foot of the hippocampus ”) from its resemblance to the paw 
THALAMUS 
HIPPOCAMPAL FISSURE", 
FI M BRIO-DENT ATE FISSURE- 
DENT ATE 
GYRUS 
MIDDLE 
HORN 
OF 
LATERAL 
VENTRICLE 
HIPPOCAMPAL 
GYRUS 
SUBCOLLATERAL 
GYRUS 
Fig. 582.—Semidiagrammatic coronal section through the middle horn of the right lateral ventricle. We 
look upon the hind surface of the front segment, and forward into the cavity. (F. H. G.) 
of some animal. The convexity of the floor results from the bending inward of 
this part of the parietes of the cavity caused by the collateral fissure, anterior to 
the part which causes the prominence in the floor of the posterior horn. Attached 
to the roof, which is made by the tapetum, are the tail of the caudate nucleus and 
the tcenia semicircularis, side by side, as they were in the body of the ventricle 
from which they are traced, and ending in front in the amygdala. Along the top THE CEREBROSPINAL AXIS. 
of the hippocampus courses the fimbria, continued from the posterior pillar of the 
fornix, of which organ it has become the sole representative. Between the 
Fig. 583.—Arterial supply of the lateral surface of the cerebral hemisphere. (Testut.) 
Fig. 584.—Arterial supply of the mesial and tentorial surfaces of the cerebral hemisphere. (Testut.) 
Fig. 585.—Arterial supply of the base of the cerebral hemisphere. (Testut.) 
fimbria and the henia the choroid plexus juts into the horn, dangling, as it were, 
from the junction of the mesial wall and the roof. 
Arteries of the Hemisphere.—The cerebral hemispheres are supplied with THE REGION OF THE THIRD VENTRICLE. 
531 
blood by the anterior, middle, and posterior cerebral arteries, which have been 
described in a previous chapter. It is only necessary here to refer to that account 
for details of course and distribution, and to call attention to Figs. 583—585, 
which show most impressively the regions to which each of these vessels furnishes 
nourishment. 
THE REGION OF THE THIRD VENTRICLE—THE THALAMEN- 
The third ventricle comprises the parts developed from the second encephalic 
vesicle and, in addition, the aula of the first vesicle—the latter constituting the 
front and upper portion, as has been related in the early part of this chapter. 
The third ventricle (Figs. 586-588) is a narrow, deep, median crevice, on a 
plane distinctly below that of the body of the lateral ventricle. It opens at its 
CEPHALON. 
OPTIC/ 
TRACT 
Fig. 586.—Coronal section of the hemispheres through the middle commissure, M. C. C. N., caudate nu 
cleus in the roof of the middle horn of the right lateral ventricle. (Testut.) 
upper, outer and front angles into the portae (foramina of Monro), by which com- 
munication is established with the lateral ventricles ; and high up on its hind wall 
it is continuous with the aqueduct. Its lateral boundaries are made by the 
thalami; its roof is furnished by the median part of the velum interpositum ; it 
is bounded in front by the anterior pillars of the fornix and the lamina cinerea; 
behind are the epiphysis (pineal gland), the posterior commissure, and the 
aperture of the aqueduct; its floor, reckoning from behind forward, is made by 
the tegmenta of the crura cerebri, the posterior perforated space, the corpora 
albicantia, and the tuber cinereum with the infundibulum and hypophysis (pitu- 
itary body); crossing it from side to side is the middle commissure ; and hanging 
down into it from the roof are the choroid plexuses of the third ventricle. 
As the thalamencephalon is intimately connected with the mesencephalon, it is necessary to 
present a brief description of the latter at this stage of our study. 
The mesencephalon is the isthmus between the higher and lower parts of the brain. It is 
perforated from end to end by the aqueduct. In front of this passage are the crura ce>-ehri 
(“legs of the cerebrum ”), two great columns which are diverging, upward continuations of the 
white substance from the pons and cerebellum. The ventral part of each crus is called crust a, 
the dorsal part tegmentum. Behind the aqueduct the material is arranged in four distinct 
knobs, the corpora quadrigemina. 532 
THE CEREBROSPINAL AXIS. 
The Thalami (Figs. 587, 588). 
The thalami, often called thalami optici (“ optic couches ”), are large masses 
of gray substance of irregular shape, presenting mesial, upper, and back surfaces, 
FORAMEN 
OF MONRO 
■ANTERIOR 
COMMISSURE 
toRPUS 
albicans) 
INFUNDIBULUM 
-OPTIC NERVE 
POSTERIOR 
COMMISSURE 
HYPOPHYSIS 
Fig. 587.—Median section through the third and fourth ventricles. Left half. M. C., middle commissure, 
(Testut.) 
which are free, and under and outer surfaces, which are attached, being blended 
with contiguous parts of the brain. The free surfaces are covered with a thin 
layer of white nervous tissue. The mesial surface of each is flattened, and forms 
ANTERIOR 
' PILLARS 
TAENIA SEMI- 
- CIRCULARIS 
Fig. 588.—Third ventricle from above. The upper surface of the thalami, the epiphysis, and the corpora 
quadrigemina are seen. (Testut.) 
a side wall of the third ventricle from floor to roof. The boundary between the 
mesial and upper surfaces is marked by a white band, the stalk of the epiphysis, 
extending from the anterior pillar of the fornix in front to the epiphysis behind. THE REGION OF THE THIRD VENTRICLE. 
533 
Along the mesial surface from the porta to the aqueduct is a groove, the sulcus of 
Monro (usually but faintly marked), indicating the line of junction of the dorsal 
and ventral zones, into which morphologists divide the encephalon. 
The upper surface is divided into a postero-internal portion and an antero- 
external portion by an oblique groove. Upon the former of these areas lies the 
velum interposition, whose free edge, the choroid plexus of the lateral ventricle, 
rests upon the latter area. A portion of this surface beyond the plexus is often, 
perhaps usually, seen in the floor of the lateral ventricle, separated from the 
caudate nucleus by the tsenia semicircularis. In the diagrams (Figs. 549 and 
552), which represented the first and second vesicles developing separately, the 
thalamus manifestly could have no place in the lateral ventricle; and it is held 
by Wilder that it is always absolutely excluded from this cavity. At the extreme 
front of this surface is a rounded end, the anterior tubercle. Behind at the inner 
side of the thalamus is another tubercle, the pulvinar (“ couch ”), which extends 
downward, and occupies the posterior surface. At the lower and outer portion 
of the posterior surface are the two corpora geniculata (“ the bended-knee 
bodies”), internal and external (Fig. 597), connected behind with the corpora 
quadrigemina by the posterior and anterior brachia, and in front continued into 
the optic tract. 
The outer surface and anterior end are closely related to the internal capsule, 
into which they send many fibres. 
The under surface rests upon a forward extension of the tegmentum. 
VEIN OF CORPUS 
STRIATUM 
-T/EN IA SEMI- 
CIRCULARIS 
ANTERIOR PEDUNCLE 
OF EPIPHYSIS 
PLEXUS OF 
THIRD VENTRICLE 
Fig 589 —Coronal section through the lateral and third ventricles, showing the velum interpositum push- 
ing the choroid plexuses (C. P.) into the lateral ventricles above the thalami. (Semidiagrammatic.) (Testut.) 
The great bulk of the thalamus is gray substance, which is divided into outer and 
inner nuclei by a thin, curved, white layer. The two thalami are connected by a 
gray band, the middle (soft) commissure, which crosses the third ventricle nearly 
at its centre. They are also united by the floor of the ventricle. 
The roof of the third ventricle is formed by the velum interpositum (Fig. 589), 
which has already been described. The endyma lining the ventricular cavity is 
reflected from the thalami onto the under surface of the velum along the lines 
marked by the peduncles of the epiphysis (pineal body). From the under sur- 
face of the velum hang the choroid plexuses of the third ventricle, covered, of 
course, by the endyma. 
Authors differ widely concerning the extent of the floor of the third ventricle. 
Some include every part of the walls excepting the sides and roof, thus making the 
floor embrace all of the parts on or near the middle line below the plane of the stalks 
of the epiphysis (pineal peduncles), which indicate the uppermost lateral boun- 
daries. Others apply the name “ floor” only to the structures extending from 
the location of the optic chiasma back to the opening of the aqueduct, considering 
all from the chiasma to the junction of the pineal peduncle with the fornix as 534 
THE CEREBROSPINAL AXIS. 
anterior wall. The latter method is pursued here, although one sees specimens 
which justify the subdivision of this floor-space so that a posterior wall of con- 
siderable extent may be described. 
From the aperture of the aqueduct the floor of the third ventricle slopes quite 
sharply downward and forward, and is made by (1) the tegmenta of the mesen- 
cephalon, (2) the posterior perforated space, (3) the corpora albicantia, and (4) the 
tuber cinereum, whose central part is the infundibulum, to which the hypophysis 
is attached. 
The tegmenta abut abruptly upon the ventricular cavity. The surface which 
they present is slightly convex, and is covered with a continuation of the 
gray matter which surrounds the aqueduct. This sheet of gray is extended 
forward beyond the limits of the tegmenta, and forms the greatest part of the 
floor. Furthermore, it rises for a little distance upon the mesial surface of the 
thalami, and thus covers the lower part of the anterior pillars of the fornix, 
where they lie against these bodies. The part of the floor in front of the teg- 
menta presents a free under surface, which is visible on the base of the brain. 
This area is rhombic, and margined in its rear portion by the diverging crura 
cerebri, in its front by the converging optic tracts. The surface area included 
by these structures is called the interpeduncular space, from its being, in part, 
between the cerebral crura or peduncles. It is composed almost wholly of gray 
substance, and is a bond of union between the two thalami. In its hind portion 
is the posterior perforated space ; in its fore part is the tuber cinereum (“ ashen 
knob”). Between these two the corpora albicantia (“whitish bodies”) are 
inserted. 
The Posterior Perforated Space, so called from its situation and appearance, is 
a forward continuation of the gray matter in the wall of the aqueduct, and 
stretches laterally between the diverging crura. t Its numerous apertures give 
passage to small vessels. 
The Tuber Cinereum is continuous behind with the posterior perforated space, 
and in front with the lamina cinerea, which forms a part of the anterior wall of 
the third ventricle. The central part of the tuber cinereum is prolonged down- 
1 N FUNDI- 
BULUM 
ward in the shape of a cone, the infund- 
ibulum, whose funnel-like cavity is a 
part of the third ventricle (Fig. 590). 
To the apex of the infundibulum is 
attached the hypophysis (“ the growth 
underneath ”) also called the pituitary 
gland, from the erroneous notion, form- 
erly entertained, that it secreted the 
mucus (pitnita), which is discharged 
from the nose. This body is lodged in 
the sella Turcica of the sphenoid bone, 
in which it is firmly held by the dura, 
the fibrous membrane lining the brain- 
case. The hypophysis is composed of 
two parts, essentially different in origin 
and histological character. The poste- 
rior portion is the smaller, and is a 
CIRCULAR. 
SINUS 
Fig. 590.—Sagittal section through the hypo- 
physis, mesial surface of right segment. (Testut.) 
process from the ventricular wall, at first being hollow and communicating with 
the ventricle, bnt ultimately losing its cavity, and consisting of nervous matter 
intermingled with much fibrous tissue. The anterior portion is ranch the larger, 
and partly embraces the posterior. It is derived from the primitive oral cavity, 
and its structure bears a resemblance to that of the thyroid body. The hypo- 
physis has been found greatly enlarged in many cases of giantism, and hence has 
been supposed to sustain a relation to the stature of the individual. 
The Corpora Albicantia (Figs. 572, 586, 587), situated about midway of the 
floor of the third ventricle, are parts of the anterior pillars of the fornix. The THE REGION OF THE THIRD VENTRICLE. 
535 
pillars are traced down from their beginning in the lateral ventricles, form a part 
of the front wall of the third ventricle, curve backward in their descent, and per- 
forate the floor of the third ventricle near its centre, thus interrupting what, 
without them, would be the complete continuity of the expanse of gray matter in, 
this region. Each pillar then turns abruptly on itself, forming the bunch which 
is named corpus albicans, and extends upward and outward to the thalamus of its 
own side, in the substance of which it disappears. In composition these bodies 
are white nervous tissue enclosing gray. They are connected with the crura 
cerebri by white fibres embedded in the gray material of the floor. The cord 
which extends from the corpus albicans to the thalamus, and which is called the 
bundle of Vicq d’Azyr, though seemingly a prolongation of the fornix, is now 
thought to have no histological continuity with it. 
The anterior wall of the third ventricle consists in its lower part of the lamina 
cinerea, otherwise called lamina terminalis. The first of these names implies that 
it is composed of gray matter, and the second that it is the uttermost boundary of 
the third ventricle. It is continuous below with the tuber cinereum, which it 
joins behind the chiasma, or optic commissure, and it blends at its sides with the 
anterior perforated spaces. Together with the tuber cinereum and posterior per- 
forated space it makes up the basal gray commissure. Its upper border is connected 
in the middle with the rostrum of the callosum by the basal white commissure, 
and laterally is continuous with the gray substance of the gyri of the under sur- 
face of the frontal lobes. It passes in front of the anterior commissure, which 
consequently lies between it and the anterior pillars of the fornix. 
The upper part of the anterior wall is supplied by the anterior pillars of the 
fornix. The lower portion of each pillar is close to the thalamus of the same side, 
and is covered, as is the neighboring surface of the thalamus, by a thin layer of 
gray matter, which is a lateral extension of the basal gray commissure. 
On each side between the anterior pillar of the fornix and the thalamus is the 
porta (foramen of Monro), an opening with a well-defined, oval margin. This is 
the developed condition of the lumen of the little sprout, which budded from the 
upper, front part of the wall of the first encephalic vesicle, and expanded at its 
distal end into the body of the lateral ventricle. It connects the third ventricle 
with the lateral. There is no passage directly from one lateral ventricle to the 
other, because the third ventricle intervenes between the two port*. It is, how- 
ever, interesting to observe that the most nearly direct course between the cavities 
of the lateral ventricles is across the fore and upper part of the third ventricle— 
the portion which is developed from the aula, the first encephalic vesicle, from 
which the lateral ventricles themselves are derived. Each porta permits the 
passage of a prolongation of the choroid plexus of its lateral ventricle. 
The remaining portion of the wall of the third ventricle is found in the small 
space between the long stalk of the epiphysis (pineal peduncle) and the opening 
of the aqueduct. It may be called the rear wall. The upper lip of the aperture 
of the aqueduct is formed by the anterior border of the quadrigeminal mass, at 
this point thickened and folded back, thus making a ridge, which stretches from 
side to side, and constitutes the posterior commissure. The fibres of this body 
apparently connect the thalami, and probably also extend into the white substance 
of the hemispheres. 
Above the posterior commissure is the epiphysis (“ the growth upon ”), other- 
wise called conarium and pineal gland, these last names being given on account 
of the fancied resemblance of the body to a pine cone. Epiphysis is the best of 
the names, because this object is an upgrowth from the second encephalic vesicle. 
At first it is hollow; but it soon loses its connection with the ventricular cavity, 
and becomes filled with epithelial cells and particles of earthy material, called 
brain-sand. The ancients had a grotesque theory that the epiphysis is the favorite 
and peculiar abiding place of the human soul. Modern morphologists have 
shown it to be the homologue of the third eye which some reptiles possess. It pro- 
jects outside of the ventricle, and rests upon the two upper quadrigemina. It has 536 
THE CEREBROSPINAL AXIS. 
a double stalk on each side. One of these is very short, and is connected with the 
posterior commissure ; the other, already described, extends from the epiphysis to 
the anterior pillar of the fornix, and indicates the upper, lateral boundary of the 
third ventricle. 
The walls of the third ventricle are so intimately blended at various points 
with those of the lateral ventricles that it is impracticable to determine the exact 
line of union ; but a portion of it doubtless lies in the internal capsule. 
There is an unbroken continuity of gray matter from the lamina cinerea at the 
front of the third ventricle to the gray surrounding the central canal of the spinal 
cord. The lamina cinerea is connected in front not only with the callosum, but 
also with the gyri of the frontal lobe, and at its sides it joins the anterior per- 
Fig. 591.—Diagram to show the continuity of the gray of the basal ganglia of the cerebral hemispheres, the 
cortex, and the lower segments of the cerebro-spinal axis. (F. H. G.) 
forated space, which is the surface area of the lenticular and caudate nuclei and 
the claustrum ; and these are connected with the gyri of the temporal lobe through 
the amygdala, which is fused with the lenticular nucleus. Keeping these facts in 
mind, it is easv to understand that the threat ganglia are only local thickenings of 
7•/##o o o # O 
the gray matter surrounding the cavity of the cerebro-spinal axis, which in the 
adult displays in the spinal cord the least change from the original condition. 
The Subthalamic Region.—The mass upon which the thalamus rests is made 
up mostly of a forward continuation of the tegmentum of the mesencephalon. 
Three layers are distinguished : the stratum dorsale, which is superior; the zona 
incerta (“the uncertain zone”), a reticulated, fibrous collection, the origin of 
which is doubtful and its boundaries obscure; and the corpus subthalamicum 
(“ body under the thalamus ”), derived from the locus niger, which lies between the 
tegmentum and crusta of the mesencephalon. Dorsal and mesial to the corpus 
subthalamicum is an extension of the red nucleus of the tegmentum. The sub- 
thalamic region thins out as it extends forward and outward, and finally becomes 
continuous with the anterior perforated space. THE REGION OF THE THIRD VENTRICLE. 
537 
The Internal Capsule. 
A horizontal section through the lenticular nucleus at any but its lowest 
levels displays this great ganglion surrounded by a thick layer of white substance.. 
The portion of this enclosing material on the mesial side is the internal capsule, 
and that between the nucleus and the claustrum is the external capsule. 
The internal capsule (Figs. 577, 586, 578, 592), as seen in horizontal section, 
following the mesial surfaces of the lenticular nucleus, forms a bend with its con- 
vexity toward the middle line. The part at the angle is the genu ; that in front 
of it is the anterior segment; and that 
behind is the posterior segment. The anterior 
segment separates the lenticular nucleus from 
the caudate; the posterior divides it from 
the thalamus ; and the genu comes up to the 
tsenia semicircularis, pushing in between 
the caudate nucleus and the thalamus. 
UPPER LINE OF IN- 
/TERNAL CAPSULE 
The internal capsule is largely composed 
of fibres which run between the cortex of 
the hemisphere above and the crura cerebri 
below. But it has ingredients which con- 
nect these parts only indirectly. Some 
fibres enter it from the end, which do not 
leave it, but plunge into the surrounding 
ganglia—the thalamus, the caudate and 
lenticular nuclei. Others enter at its sides 
from the same gray masses, and emerge 
from the end. Certain fibres come to it 
from the subthalamic region, and still others 
from the hemisphere of the opposite side 
through the callosum. The general drift 
UPPER LINE 
OF CRUS 
Fig. 592.—Diagram of the composition of the 
internal capsule. (Testut.) 
of its direction, however, is between the lowest and the highest centres of the 
cerebro-spinal axis—from below upward and outward. Tracing the fibres upward 
wre find that, immediately on emerging from the capsule, they spread out in every 
direction toward the cortex, constituting the corona radiata { “ the radiant crown 
The anterior segment is chiefly composed of fibres coursing longitudinally 
between the thalamus and the cortex of the frontal lobe. The hind portion of 
the posterior segment is a continuation of the lemniscus, and the remaining por- 
tions are connected with the region of the cortex about the central (Rolandic) 
fissure. 
At various places, particularly in its anterior part, the internal capsule is 
streaked with cords of gray, which cross it between the caudate and lenticular 
nuclei. 
The External Capsule (Fig. 577), which is situated between the lenticular 
nucleus and the claustrum, is united to the internal capsule below and behind. It 
is composed of fibres contributed partly by the anterior commissure, and partly 
by the subthalamic region. 
Diagrammatic Description of the Lowest Parts of the Brain.—Before entering 
upon the detailed study of the remaining structures of the brain, which are 
related to one another in a very intimate and complex manner, it is well to con- 
sider them in a schematic way, by which the principal features of their gross 
anatomy shall be presented clearly and form the groundwork for the more minute 
consideration of the subject (Fig. 593). This, in part, has been done on a pre- 
vious page, but may profitably be reviewed at this stage. 
The cerebral hemispheres and the parts in the region of the third ventricle, 
already described, are developed from the first and second encephalic vesicles. 
From the third vesicle is developed the mesencephalon, from the fourth the pons 
and cerebellum, and from the fifth the oblongata. 538 
THE CEREBROSPINAL AXIS1. 
The mesencephalon is often called the isthmus of the brain, because it is the 
narrow neck by which the great cerebral mass above is connected with the struct- 
ures below. Its ventral part is shaped like two pillars converging to the pons, 
and is called the crura cerebri; its dorsal protrudes in four tubercles, the corpora 
quadrigemina. Its cavity is the aqueduct. 
The cerebellum is a large, solid body, the second of the brain-masses in size, 
and constitutes the dorsal portion of the wall of the fourth ventricle. It is con- 
nected above by the superior cerebellar peduncles with the quadrigemina ; in front 
by the middle cerebellar peduncles 
with the pons ; and below by the 
inferior cerebellar peduncles with 
the oblongata. 
The pons is situated between 
the isthmus above and the oblon- 
gata below, and forms the ventral 
part of the wall of the fourth 
ventricle. It bulges in front and 
laterally, and runs back on each 
side into the middle cerebellar 
peduncle. Between the dorsal 
surface of the pons and the ven- 
tral surface of the cerebellum is 
the upper half of the fourth ven- 
tricle. 
Below the pons is the oblon- 
gata, developed from the fifth vesicle. It is shaped like an irregular, inverted, 
truncated cone. Below it is continuous with the spinal cord. The upper part 
of its cavity is the lower part of the fourth ventricle proper, and the rest of it is 
tubular and directly continuous with the central canal of the spinal cord. 
The columns of fibrous nervous tissue are chiefly continued upward from the 
spinal cord through the oblongata, the pons, and the isthmus, to the higher levels 
of the brain; but some of them switch off dorsally to the cerebellum, thus con- 
stituting the inferior peduncle of that body. The gray nervous tissue, also, is 
continued upward from the cord, and a portion of it is thus connected with the 
highest collections of gray matter in the cerebrum; but in the oblongata con- 
siderable masses are detached by the intrusion and crossing from one side to the 
other of large bundles of white nervous tissue, and at various points are found 
new collections of nerve-cells, which are not the representatives of any nuclei at 
lower levels. 
.QUADRIGEMINA 
SUPERIOR PEDUNCLE 
DEVELOPED 
FROM THIRD 
ENCEPHALIC 
VESICLE 
DEVELOPED 
FROM FOURTH 
ENCEPHALIC 
VESICLE 
PONS 
MIDDLE 
PEDUNCLE 
CEREBELLUM 
DEVELOPED 
FROM FIFTH 
ENCEPHALIC 
VESICLE 
'INFERIOR PEDUNCLE 
Fig. 593.—Diagram of the parts of the encephalon below 
the thalami, left side. 
THE MESENCEPHALON: 
The Region of the Aqueduct. 
Next below the thalamencephalon comes the mesencephalon, otherwise known 
as the mid-brain, from its situation, and as the isthmus cerebri, because it is the 
constricted bond of union between the parts which result from the development 
of the first and second encephalic vesicles and those which come from the fourth 
and fifth. Its direction is from before backward and a little downward. Viewed 
from below it displays a ventral surface, which is marked by two short, thick, 
white columns, converging toward the pons, like the limbs of the letter V, and 
called the crura cerebri (“ legs of the brain ”), and also the cerebral peduncles 
(“little feet”) (Fig. 596). Between the crura is a triangular area, already 
described as the hind part of the interpeduncular space (see page 534). 
The dorsal surface is not visible until certain overlying structures have been 
removed. It then presents to view four prominent knobs, the corpora, quadrigemina 
(“ four-twin bodies ”), and the upper portion of the superior cerebellar peduncles 
(Fig. 597). The quadrigemina are arranged in pairs, an upper (anterior) pair, THE MESENCEPHALON. 
539 
sometimes called the nates, and a lower (posterior), known also as the testes. A 
median groove separates the right tubercles from the left, and ends above at the 
posterior commissure ; and the superior are divided from the inferior by a trans- 
verse gutter. At the outer sides the quadrigemina run upward and forward into 
the brachia (Fig. 597). 
A cross-section of the isthmus (Figs. 
594, 595) shows that each lateral half is 
divided into two unequal parts by a band 
of nerve-cells, so deeply pigmented as 
to have received the name of locus niger 
(•‘the black place”). Ventrally to this 
is the column of white nervous tissue which 
forms a side boundary to the interpeduncular 
space, and is called the crusta (“ crust ”). 
Dorsally is a mass of mingled white and 
gray, the tegmentum (“ covering ”). At each 
border the locus niger comes to the surface 
at a groove, that which is mesial being the 
AQUEDUCT 
CORPORA QUADRIGEMINA 
-TEGMENTUM 
■LATERAL GROOVE 
LOCUS NIGER 
CRUSTA 
INTERPEDUNCULAR 
Fig. 594.—Transverse section of the mesen- 
cephalon. (Testnt.) 
place of emergence of the third cranial nerve, and the other, called the lateral groove, 
runs from the internal geniculate body to a point between the superior and middle 
peduncles of the cerebellum. The crusta is largely composed of flat bundles of 
white tissue which present their edges at the free surface. The part of the crusta 
close to the locus niger is the stratum intermedium. The tegmentum extends from 
AQUE 
OCULO-MOTOR, 
NUCLEUS 
LATERAL, / 
GROOVE*^ 
RED 
NUCLEUS 
RED 
NUCLEUS 
LOCUS 
NIGER' 
CRUST A- 
ROOTS OF 
OCULO-MOTOR 
STRATUM 
Fig. 595.—Transverse section through the anterior quadrigemina. (Testut, after Stilling.) 
INTERMEDIUM 
the locus niger up to the level of the aqueduct, and above this plane is the lamina 
quadrigemina, upon which the corpora quadrigemina rest. The aqueduct is a 
small canal and is surrounded by a considerable thickness of gray, in which are 
embedded clusters of nerve-cells, which are connected with the roots of the third, 
fourth, and fifth cranial nerves. In the fore part of the tegmentum is a globular 
collection of cells, the red nucleus, through which pass the roots of the oculo- 
motor (third) nerve. On the surface of the tegmentum above the lateral groove 
appears the external portion of the lemniscus. The anterior extremity of the 540 
THE CEREBROSPINAL AXIS. 
tegmentum is convex, and slopes downward and forward, forming a part of the 
floor of the third ventricle. Upon this surface is extended the forward continua- 
tion of the gray of the aqueduct. The locus niger can be traced backward to the 
upper margin of the pons, and forward to the corpora albicantia. The white 
around the red nucleus is an extension of the greater part of the superior cere- 
bellar peduncle of the opposite side—decussation taking place across the middle 
line in the raphe. As a whole the white of the crura is a continuation of 
bundles from the internal capsule and subthalamic region. 
THE EPENCEPHALON. 
This segment of the brain comprises the parts developed from the fourth 
encephalic vesicle, namely, the pons and the cerebellum. 
The pons, otherwise called pons Varolii (“ bridge of Varolius ”) and tuber annu- 
lare (“ annular protuberance ”), consists largely of white nervous tissue, the greater 
part of which is divided into two groups of bundles, according to the direction in 
The Pons. 
which they run (Figs. 587, 596). One set 
courses nearly vertically from the mesen- 
cephalon to the oblongata, occupying the 
central portion of the pons; the other, 
mainly superficial to this, is disposed horizon- 
tally, and is seen at the front and sides, pro- 
jecting beyond the surface plane of the crura 
and the oblongata. The horizontal part gives 
the name to the whole, because it suggests 
the arch of a bridge connecting the lateral 
halves of the cerebellum. The ventral por- 
tion of the arch has the greatest vertical 
diameter, and the sides taper as they go 
dorsally, being smallest where they enter the 
cerebellum, constituting the middle peduncles 
of this organ. 
By removing the cerebellum, a view is 
obtained, of the dorsal aspect of the pons 
(Fig. 597). On each side is seen a superior 
peduncle of the cerebellum, running down- 
ward and outward from the quadrigemina. 
Between these two diverging masses is 
stretched a flat, triangular plate, consisting 
CORPUS ALBICANS 
FIRST CERVICAL 
NERVE 
Fig. 596.—Ventral view of mesencephalon, 
pons, and oblongata. (Testut.) 
of two layers of nervous tissue, the ventral being white, the dorsal gray. This 
structure is variously called the valvula, the valve of Yieussens, and the ante- 
rior medullary velum. It forms the upper part of the dorsal wall or roof of the 
fourth ventricle. Cutting away the valvula, we look into the fourth ventricle, 
and see the upper portion of its ventral wall or floor, overlapped at its sides by 
the mesial borders of the superior cerebellar peduncles. In the entire middle line 
of this triangular area is a groove, close to which and to the oblongata is a 
rounded projection, the eminentia teres (“the round eminence”). Beside this is a 
shallow depression, the fovea superior (“ the upper little pit”), and above the 
latter a deeply pigmented area, the locus ceruleus (“ the blue place ”). 
A cross-section of the upper portion of the pons shows that the bulk of its 
ventral and larger part is composed of transverse bundles, with which are 
intermingled those which run longitudinally. The dorsal and smaller por- 
tion has a reticular formation in the centre, behind which is a thin layer of gray 
tissue, and in front of it a part of the fillet or lemniscus—a structure which will THE EPEN CEPIIA L ON. 
541 
be described later, when all the segments of the encephalon in which it is found 
have been considered 
LEFT THALAMUS 
POSTERIORI 
BRACHIUM- 
THIRD 
VENTRICLE 
(raised) 
ANTERIOR 
BRACHIUM 
Ij EPIPHYSIS 
CORPUS GENICULA 
TUM EXTERNUM 
CORPORA 
v QUADRIGEMINA 
TROCHLEAR NERVE 
LEMNISCUS 
OPTIC TRACT- 
„ VALV U LA 
SUPERIOR 
PEDUNCLE 
FOURTH 
[ VENTRICLE 
.INFERIOR 
PEDUNCLE 
MIDDLE' 
PEDUNCLE 
Fig. 597.“-Dorsal view of the mesencephalon, pons, and oblongata. The thalami and epiphysis are drawn 
upward, the optic tract downward. (Testut.) 
The Cerebellum. 
The cerebellum is the great, solid, nervous mass lying dorsal to, and on the 
same plane with, the pons, with which it is developed from the fourth encephalic 
vesicle (Fig. 598). It is situated in the posterior fossa of the cranium, and is 
FORAMEN 
OF MONRO 
ANTERIOR 
COMMISSURE 
■OPTIC NERVE 
CORPUS 
.ALBICANSI 
NFUNDIBULUM 
| POSTERIOR 
COMMISSURE 
HYPOPHYSIS 
Fig. 598.—Median section through the third and fourth ventricles. Left half. M. C., middle commissure, 
(Testut.) 
shielded from the pressure of the overlying cerebral hemispheres by a strong, 
tightly stretched prolongation of dura, called the tentorium. It has no cavity 542 
THE CEREBROSPINAL AXIS. 
proper to itself, but it participates in the formation of the roof of the fourth ven- 
tricle. Its main portion consists of three parts, a median and two lateral, all 
continuous and of substantially the same structure. 
The lateral parts are called hemispheres—a piece of nomenclature imitative of 
that of the great cerebral masses, rather than appropriate on account of its 
inherent descriptiveness. These bodies attain a size so greatly in excess of that 
reached by the median portion, which is between them, that the latter is com- 
paratively insignificant, and its obscuration by them on the lower aspect is almost 
complete in the normal position of the parts. 
The median portion is called the vermis (“worm”) or vermiform process, on 
account of the undulatory appearance of its irregular surface. On the upper 
aspect of the cerebellum the vermis and hemispheres are separated only by slight 
grooves; but on the under surface the vermis is sunk almost out of sight in a 
deep dorso-ventral depression, the vallecula (“ little vale ”), which ends behind 
in a deep notch, in front in a shallow one. 
The cerebellum is connected with other parts of the encephalon by six bands, 
three on each side. To the oblongata run the inferior peduncles, previously 
described as the restes. To the quadrigeminal bodies of the isthmus stretch the 
superior peduncles, which have been seen to bound the pontile portion of the 
fourth ventricle laterally. To the pons go the middle peduncles, which spread out 
into its ventral protuberance. 
The upper surface of the cerebellum is nearly flat, the lower surface decidedly 
convex. Both surfaces are marked with fissures which run in a generally trans- 
verse direction, and are so close together as to divide the cerebellar substance 
into layers or leaves, whence it is said to be laminated or foliated. These folia 
are very different in gross appearance from the gyri of the cerebrum, presenting 
a sharp border instead of a rounded surface ; but they are homologous with these 
gyri in that they have a basis of white substance and upon this a covering (cor- 
tex) of gray. The clearest conception of the depth and arrangement of the folia is 
obtained by making sections, especially in a vertical direction, through the cere- 
bellum at different planes (Fig. 599). It is then seen that the white substance 
SUPERIOR LObes 
MIDDLE 
CEREBELLAR 
. PEDUNCLE 
.FLOCCU- 
LUS 
Fig. 599.—Sagittal section of left cerebellar hemisphere. (Testut.) 
forms a large core or trunk, the trapezium, from which a number of primary 
branches are given off. Each of these in its turn divides, and, as the ultimate 
rami, as well as the original, are clothed in gray, an appearance is presented sug- 
gestive of a cedar tree, whence the name arbor vitce (“ tree of life ”), which is 
given to it. 
The upper and lower surfaces are separated by a rather prominent border, 
partly upon and partly near which runs the longest and deepest of the fissures, 
the great horizontal or longitudinal fissure. 
The upper surface is marked in the middle line by the superior vermis, whose 
central and most pronounced prominence is the monticulus (“ little mountain”). 
On each side of the vermis is a shallow groove, beyond which is a hemisphere. THE EPENCEPHALON. 
543 
The deep fissures divide the entire upper portion of the cerebellum into segments, 
which are seen most favorably in sagittal sections. For each segment of the ver- 
mis there is a corresponding and connected part of each hemisphere. These do 
not appear plainly in the picture (Fig. 600), but will be understood by reference 
to the schematic arrangement, in which the segments are named in order from 
before backward, with the fissures which separate them. The segments of the 
vermis are the lingula (“ little tongue”), the central lobe, the culmen (“summit”), 
the clivus (“ slope ”), and the cacumen (“ top ”) ; and the parts of the hemisphere 
respectively corresponding are the frenulum (“little bridle”), the ala (“wing”), 
the anterior or ventral crescentic lobe, the posterior or dorsal crescentic lobe, and 
TROCHLEAR NERVE 
.CENTRAL LOBE 
GREAT HORIZON 
Fig. 600.—Upper surface of cerebellum. The lingula and cacumen are concealed by overhanging parts 
Compare with scheme of this surface. (Testut.) 
TAL FISSURE 
the dorso-superior lobe. The fissures are named with reference to their situation in 
front of or behind the central lobe and the clivus—precentral fissure, postcentral 
fissure, preclival fissure, and postclival fissure. 
Upper Surface of Cerebellum. 
LINGULA. 
CENTRAL LOBE. 
CULMEN. 
CLIVUS. 
CACTJMEN. 
VERMIS. 
FRENULUM. 
PRECENTRAL FISSURE. 
ALA. 
POSTCENTRAL FISSURE. 
VENTRAL CRESCENTIC LOBE. 
PRECLIVAL FISSURE. 
DORSAL CRESCENTIC LOBE. 
POSTCLIVAL FISSURE. 
DORSO-SUPERIOR LOBE, 
HEMISPHERE. 
The under surface presents in the mid-line the inferior vermis, separated super- 
ficially from the hemispheres by lateral grooves. Here, as on the upper aspect 
of the cerebellum, the deep fissures cut so far into the substance as to mark off 
segments; but the portions of the hemispheres are less easily seen to be related 
to correspondent parts of the vermis than in the former case. The fissures are 
not as regularly disposed, and the whole arrangement is complicated. Close ex- 
amination, however, reveals a more systematic relation than casual inspection 
promises, and this is shown diagrammatically in the schematic table, which would 544 
THE CEBEBBO-SPINAL AXIS. 
best be studied in connection with the picture (Fig. 601). From before backward 
are seen in the vermis the nodule, the uvula, the pyramid, and the dorsal tuber 
(tuber posticum); and in the hemisphere the flocculus (“ little tuft of wool”), the 
amygdala (“ almond ”), the biventral or digastric lobe, the slender lobe, and the 
dorso-inferior lobe. The uvula and amygdalae are so named on account of their 
TRIFACIAL 
NERVE 
Fig. 601.—Under surface of cerebellum. The hemispheres are pulled apart to give a view ot the inferior 
vermis. The nodule does not appear; the tuber is not labelled. Compare with scheme of this surface. (Testut.) 
resemblance to the parts of the same name in the pharynx, as seen through the 
open mouth. The fissures are named from their position with reference to the 
nodule, the pyramid, and the slender lobe—the postnodular fissure, the pre- 
pyramidal fissure, the postpyramidal fissure, and the postgracile fissure. 
Under Surface of Cerebellum. 
VERMIS. 
HEMISPHERE. 
NODULE. 
UVULA. 
PYRAMID. 
DORSAL TUBER. 
FLOCCULUS. 
POSTNOD ULAR FISSURE. 
AMYGDALA. 
PBEPYEAMIDAL FISSURE. 
DIGASTRIC LOBE. 
POSTPYRAMIDAL FISSURE. 
"SLENDER LOBE. 
POSTGRACILE FISSURE. 
. DOESO-TNFERIOR LOBE. 
Embedded in each hemisphere is a nucleus, called the corpus dentatum 
(“toothed body”) from its jagged outline (Fig. 602). Its centre is white, and 
on the mesial side near the front the gray wall is deficient. Near this are three 
other masses of gray of small size—the nucleus emboliformis (“ pluglike ”), the 
nucleus globosus (“spherical”), and the nucleus fastigii (“of the summit”). 
The general method of arrangement of the fibres traced into the cerebellum 
from its peduncles is shown in Fig. 603. 
The superior peduncle is mainly made up of fibres from the corpus dentatum 
and the cerebellar cortex. The middle peduncle is composed of fibres from cells 
in the cortex. They run to cells on both sides of the pons, and do not, as gross 
appearances suggest, go around from one side of the cerebellum to the other. The 
inferior peduncle receives fibres from cells of the cerebellar cortex and the oblon- 
gata, from the direct cerebellar tract of the spinal cord, and from the nuclei 
gracilis and cuneatus. THE OBLONGATA. 
545 
Fig. 602.—Cerebellum in nearly horizontal section—the upper surface of the lower section. (Testut.) 
THE OBLONGATA. 
The oblongata, also called medulla oblongata (“ the oblong marrow”), and the 
spinal bulb, extends from the lower margin of the pons to a plane passing trans- 
versely just below the decussation of the pyramids, at which level the spinal cord 
begins. It is shaped somewhat like an inverted truncated cone, flattened ventro- 
dorsally. It lies upon the basilar process 
of the occipital bone, the inclination of which 
indicates the attitude of the oblongata. 
CORPUS ALBICANS 
FIRST CERVICAL 
JSIERVE 
Fig. 603.—Semidiagram of the three cerebellar 
peduncles. (Testut.) 
Fig. 604.—The pons and oblongata, ventral 
view. (Testut.) 
On the ventral surface is a longitudinal cleft, the ventro-median fissure, which 
begins above in a little pit, the foramen ccecum (“ blind hole ”), and is interrupted 
below by a criss-cross of nerve-bundles. On each side of the ventro-median 
fissure is a white body, gradually dwindling from above downward, and seeming 
to be directly continuous with the ventral column of the cord. These are the 
ventral pyramids, and the interlocking of the bundles at their lower part across 
the ventro-median fissure (constituting the above-mentioned criss-cross) is called 
the decussation of the pyramids. At the outer side of each pyramid is a cleft, the 
ventro-lateral fissure, which is in line with the series of origins of the ventral 
roots of the spinal nerves. 
On each side the oblongata presents a vertical mass, the lateral column, or 
lateral tract, which is apparently continuous below with the lateral column of the 
cord, and above is encroached upon at the front part by a large ovoid mass, 546 
THE CEBEBBO-SPINAL AXIS. 
the olive (olivary body, inferior olive), whose presence crowds the column back- 
ward, and compresses it into a small band. The olive and lateral column are 
separated from the ventral pyramid by the ventro-lateral fissure, and from the 
dorsal structure of the oblongata by the dorso-lateral fissure, in which is seen a 
series of root-bundles, ranged in line with the dorsal roots of the spinal nerves. 
The dorsal surface (Fig. 605) of the oblongata is wide above and narrow 
below, and may well be described as consisting of upper and lower halves. The 
upper half presents at each side a column of white nervous material, the restis, or 
restiform (“ rope-like ”) body—another name for the inferior cerebellar peduncle 
—which is prolonged downward into the fasciculus cuneatus, the last being con- 
tinuous with the dorso-lateral column (tract of Burdach) of the cord. The two 
restes are widely separated above, but converge toward the middle line below. On 
TROCHLEAR NERVE- 
“LEMNISCUS 
LATERAL GROOVE OF 
. MESENCEPHALON 
CONDUCTOR SONORUS— 
ACOUSTIC TUBERCLE- 
AUDITORY NERVE 
STRI/E ACUSTIOKL 
HYPOGLOSSAL A R EA/ 
VAGUS A 
FOVEA INFERIOR , 
OBEX 
DORSAL MEDIAN) 
DORSO-INTERMEDI ATE 
FISSURE 
FISSURE 
IDO RSO- LATE R A L 
FISSURE 
Fig. 605.—Fourth ventricle laid open by removal of its roof. (Testut.) 
the mesial side of the restis is a band, which from a thin beginning, thickens as it 
passes downward, and becomes continuous with the fasciculus gracilis, which is 
prolonged into the dorso-mesial column of the cord (tract of Goll), separated 
from its fellow of the opposite side by the dorso-median fissure. It is called the 
dorsal pyramid (posterior pyramid). 
The restis and dorsal pyramid of each side together form a prominent ridge, 
and the two ridges by their convergence enclose a triangular space. Stretched 
across this space is a membrane, consisting of a ventral layer of endyma and a 
dorsal layer of pia. This is one of the places where the nervous tissue of the 
encephalic wall has completely disappeared, and has left its serous lining and 
vascular covering, which have come together, and formed a membrane, here 
called the posterior medullary velum, or metatela. Frora its ventral surface depend 
small clumps of blood-vessels, covered, of course, by endyma, and named the 
choroid plexuses of the fourth ventricle. Below its middle is a perforation—the THE OBLONGATA. 
547 
foramen of Magendie, or metapore, through which the cerebro-spinal fluid mingles 
with the fluid in the serous cavity which surrounds the axis. In connection with 
the membrane should be mentioned the obex, a small layer of gray substance, 
which is stretched across the very apex of the triangle; and the ligula, a small 
irregular lamina of white nervous tissue, which projects slightly over the mem- 
brane from each lateral border. Both of these structures are rudimentary. 
If the membrane is removed, the cavity of the fourth ventricle is exposed, 
and we see the part of its floor which is directly continuous with the portion pro- 
vided by the pons. The space presents a triangle, whose base is applied to that 
of the pons. The apex of the triangle has been likened to the nib of a pen, and, 
consequently, is referred to as the calamus scriptorius (“ the writing pen ”). The 
median cleft of the pons is continued down through the oblongata, and on each 
side of it are arranged from within outward three somewhat triangular areas— 
the internal white, the middle gray, and the external white—the first and third 
standing in relief. Running from the mid-line outward is a variable number 
of nervous threads, striae acusticce (“ auditory stripes ”), which turn around the 
restes, and end in the auditory nerve. 
The lower half of the dorsal part of the oblongata is marked by the dorso- 
median fissure and on each side by the dorso-lateral fissure, and between them is 
the dorsal column, which is unequally divided by the dorso-intermediate fissure 
into a smaller, mesial column, the fasciculus gracilis (“ slender bundle ”), which 
is continued downward into the dorso-mesial column of the spinal cord (the tract 
of Goll), and a larger column, the fasciculus cuneatus (“ wedge-shaped bundle ”), 
which is prolonged downward into the dorso-lateral column of the cord (the tract 
of Burdach). At about the junction of the lower part of the oblongata with its 
upper, expanded portion the fasciculi gracilis and cuneatus contain each a mass 
of gray, which is known as its nucleus. Thus we have the nucleus gracilis and 
the nucleus cuneatus. The cavity of this part of the oblongata is tubular, like 
that of the cord into which it runs. 
Internal Structure of the Oblongata. 
Transverse sections of the oblongata at different levels show marked varia- 
tions in the disposition of its constituent elements. It is manifest that the out- 
line of these sections will be strikingly different, for, as we know, the uppermost 
portion is spread out laterally, while the lowest is bunched together into a com- 
pact cylinder. The change in the arrangement of the included parts follows this 
general trend, and is shown particularly well in the case of the gray masses— 
these being small and dispersed in the higher levels, and being gradually gathered 
together as they are traced downward, until they are united into a single, coherent 
mass of definite form. 
A horizontal section at the middle of the olives shows the cavity of the fourth 
ventricle at the extreme dorsal limit (Fig. 606). The dorsal boundary is broad 
and nearly flat, the ventral is narrow and broken in the middle by the ventro- 
median fissure, and each lateral undulates between these two, the whole periphery 
being described in generous curves. A median raphe is made by a criss-cross of 
white fibres, and on each side of it the surface is divided into three unequal terri- 
tories by the fibres of the tenth and twelfth cranial nerves. The tenth (pneumogas- 
tric) nerve marks off a dorso-lateral portion, the twelfth (hypoglossal) a ventro-mesial 
area, and the large space enclosed between these two has its superficial margin at 
the side. In the ventro-mesial area is the pyramid, and just dorsal to it is the 
fillet—which will be described as a whole later. The arciform nuclei are partly 
wrapped around the pyramids. In the lateral area appears the nucleus of the 
olive, here looking like a broad, crinkled band of gray and nearly surrounding a 
space of white. The toothed appearance of this capsule has led to its being 
called the dentate nucleus. Two accessory olivary nuclei are observed, one show- 
ing as a short, broad line, near the opening of the main nucleus, the other on the 548 
THE CEREBROSPINAL AXIS. 
mesial side of the hypoglossal nerve and parallel to it. Following the hypo- 
glossal dorsally we find it terminating in a nucleus in the floor of the fourth ven- 
tricle ; and its accessory nucleus near the olive is connected with its main nucleus 
by a band. Partly merged with this accessory nucleus is the nucleus ambiguus, 
which is the motor centre of certain mixed nerves, and a band parallel to that 
joining the two hypoglossal nuclei connects the ambiguus with a mass of gray in 
the floor of the ventricle—the sensory nucleus of the same mixed nerves. Fol- 
HYPOGLOSSAL 
NUCLEUS 
SENSORY NUCLEUS 
NUCLEUS CUNEATUS 
HEAD OF DORSAL HORN 
ROOT OF TRIFACIAL NERVE 
MOTOR NUCLEUS OF MIXED 
NERVES 
ACCESSORY HYPOGLOSSAL 
NUCLEUS 
OLIVE 
HYPOGLOSSAL NERVE 
VENTRAL 
Fig. 606.—Transverse section of the oblongata at the middle of the olives. (Testut, after Duval.) 
LEMNISCUS VENTROMEDIAN ARCIFORM PYRAMID 
FISSURE NUCLEUS 
lowing the line of the pneumogastric nerve, we see that it courses through a mass 
of gray tissue, a sprout from which is the cuneate nucleus, and its rounded end 
the head of the dorsal horn—a name which will be appreciated a little later, when 
the various nuclei are brought together. Capping the head of the dorsal horn is 
a bunch of fibres, constituting a root of the fifth nerve—the trifacial; and between 
the sensory and cuneate nuclei is a bundle known as the solitary fasciculus. 
A parallel section through the lotver end of the olives shows a different arrange- 
ment (Fig. 607). The general outline approaches the circular, the tenth nerve is 
DORSOMEDIAN FISSURE 
NUCLEUS GRACILIS 
NUCLEUS CUNEATUS 
BASE OF VENTRAL HORN 
ROOT OF TRIFACIAL CAPPING 
HEAD OF DORSAL HORN 
PNEUMOGASTRIC NERVE 
HEAD OF VENTRAL HORN 
■OLIVE 
NERVE 
LEMNISCUS VENTRAL PYRAMID 
Fig. 607.—Transverse section of the oblongata at the lower end of the olives. (Testut, after Duval.) 
near the transverse axis, and the nuclei dorsal to it are larger and nearer to each 
other. The pyramid is smaller; the fillet has spread out, and its lateral edge is 
almost at the surface ; the corrugated nucleus of the olive is shrunken, its mesial 
accessory nucleus is larger, its other accessory has disappeared; in the lateral area 
appears the head of the ventral horn, the base of the same occupying a median 
position at the focal point of the tenth and twelfth nerves; just dorsal to the 
base of the ventral horn is that of the dorsal horn, from which curves dorsally 
the nucleus gracilis (Goll), separated but a little from its lateral companion, the 549 
THE OBLONGATA. 
nucleus cuneatus (Burdach) ; and connected with the last is the head of the dorsal 
horn, related, as in the first section, to a root of the trifacial nerve. 
A lower section exhibits further changes (Fig. 608). The pyramid and fillet 
are smaller; the head and base of the ventral horn are nearer; the tenth nerve 
has vanished ; all of the remaining gray masses are drawing together; the sides 
NUCLEUS 
GRACILIS 
•HEAD OF DORSAL HORN 
LEMNISCUS 
lASE OF VENTRAL KORN 
HEAD OF VENTRAL HORN 
Fig. 608.—Transverse section of oblongata at the crossing of the fillets. (Testut.) 
of the oblongata have grown up around the middle line, and have shut in deeply 
the ventricle, which in this lowest part is tubular; and from the nuclei gracilis 
and cuneatus thick bundles of fibres course 
ventrally, decussate in the middle line, and end 
in the fillet of the opposite side. 
Through the middle of the decussation of 
the pyramids the section has a practically cir- 
cular outline (Fig. 609). The pyramid is 
smaller than before, and from it runs dorsal ly 
a bundle of fibres, which crosses its fellow 
of the opposite side in the middle line. The 
fillet is no longer seen ; the base and head of 
the ventral horn are closer, being now sepa- 
rated only by the decussating bundles of the 
pyramid ; the base of the dorsal horn is nearer 
the centre of the section, its head is smaller ; 
DORSAL MEDIAN 
FISSURE 
SENSORY 
'ROOTS 
ROOTS 
VENTRAL MEDIAN 
FISSURE 
the nucleus cuneatus is lost, and the nucleus 
gracilis stretches out as a long process from 
Fig. 609.—Transverse section of oblon- 
gata at the decussation of the pyramids. 
(Testut, after Duval.) 
the base of the dorsal horn. The ventral and dorsal median fissures are shallow, 
and from the latter a neurogliar septum stretches to the central gray mass. 
Nerve-roots are given off from 
the heads of both horns. 
DORSAL 
ROOTS 
v\ 
DORSAL MEDIAN 
FISSURE 
DORSO-LATERAL 
/ COLUMN 
Finally, a section at the line 
between oblongata and cord (Fig. 
610) shows that the nucleus 
gracilis has been left above, and 
that the other gray masses are 
completely united, and are ar- 
ranged in a form suggestive of 
the letter X, the canal being in 
the centre of the crossing arms. 
The dorsal limbs of the X are 
DORSAL 
HORN 
crossed pyram- 
idal tract 
VENTRAL.. 
HORN 
VENTRAL/ 
ROOTS 
the dorsal horns, the ventral 
limbs the ventral horns, the 
Fig. 610.—Transverse section of the oblongata at its lower 
end. (Testut.) 
VENTRAL MEDIAN 
FISSURE 
limbs the ventral horns, the 
base of each horn being the 
part near the centre, the head 
being the free extremity. In each lateral half, between the dorsal horn and the 550 
THE CEREBROSPINAL AXIS. 
side, is an oval area, which indicates the destination of the part of the ventral 
pyramid which has crossed the middle line in the process of decussation. 
This series of sections clearly reveals the fact that, progressively from above 
downward, there is a diminution in the amount of gray material, and a drawing 
together of its scattered masses. 
Proceeding in the other direction—-from below upward—wre see that there is 
an addition of nuclei, a breaking up and dispersion of the gray mass of the lowest 
level, and that this scattering is caused by the oblique crossing from one side to 
the other of motor and sensory bundles. Examining the series of sections in 
reversed order, it is found that, at the first step, the heads of the ventral columns 
are amputated by the great bundles of fibres from the decussating pyramids, and 
the dorsal horns have had added to them the nuclei graciles. Next, the nuclei 
cuneati appear, and large fasciculi from them and the nuclei graciles sweep 
forward and inward, cross their opposite fellows at the middle line, and turn up 
at the back of the pyramids, forming the fillets. This performance results in the 
decapitation of the dorsal horns, just as the pyramidal bundles cut off the heads 
of the ventral horns. The succeeding step marks more emphatically the separa- 
tion of the various heads from their respective bases, and introduces the olive. At 
last, the lateral spreading of the dorsal portion throws the hind parts outward, 
brings the cavity and the bases of the horns to the rear, while the nuclei graciles 
disappear. What has before been called the base of the ventral horn now 
assumes the role of the hypoglossal nucleus, and the head of this horn has 
become the accessory hypoglossal nucleus and the nucleus ambiguus. 
At several points in the description of the lower segments of the brain, it has 
been necessary to refer to the lemniscus or fillet, but a complete account of its 
course could not be appreciated until the structures of which it formed a part 
were measurably understood. Now, however, it may be considered with profit. 
The Lemniscus. 
The lemniscus (“ the fillet ”) (Figs. 605-607) is a band, extending from the 
middle horizontal plane of the oblongata to the level of the quadrigemina. Its 
principal portion originates in the nuclei gracilis and cuneatus, which are situated 
in the dorsal part of the oblongata, and are the terminal stations of the funiculi 
gracilis and cuneatus, which are the upward prolongations of the dorsal tracts of 
the cord. It begins by running nearly horizontally forward and inward across the 
middle line of the oblongata, decussating with its opposite fellow above the plane 
of the pyramidal decussation, and reaching the dorsal surface of the pyramid. 
At this point it bends upward, and courses along close to the pyramid, being 
joined in this region by the fibres of the ascending lateral tract (Gowers) of the 
cord, which has come up through the lateral tract of the oblongata and its lateral 
nucleus (Rolando). Thus it is seen that the lemniscus embraces all of the sensory 
fibres which have come from the cord. 
Passing into the pons, the lemniscus occupies the ventral stratum of the dor- 
sal part, enters the mesencephalon, where a portion appears on the surface of the 
tegmentum, and almost all of it courses dorso-ventrally through this segment of 
the brain to the subthalamic region. There its fibres divide into two sets, one of 
which runs through the dorsal limb of the internal capsule, and thence passes to 
the cortex of the central area; while the second set, of greater size, enters the 
thalamus, and ends there in arborizations around the cells—from which last, 
however, other fibres run to the gyri around the central fissure, like the first 
group. The essential difference between the two sets is that one goes directly, the 
other through a thalamic interruption, to the sensori-motor area of the cerebral 
cortex. 
The Fourth Ventricle. 
We have now studied separately the various structures enclosing the part of 
the encephalic cavity which is known as the fourth ventricle, and it will be well THE OBLONGATA. 
551 
to consider them in their natural connections as the continuous walls of this 
chamber. 
The upper, wide-spread portion of the fourth ventricle (that part which is 
usually thought of when the ventricle is named) is nearly rhomboidal or lozenge- 
shaped. It presents a ventral part, called the floor'; a dorsal part, the roof; an 
upper or anterior angle, a lower or posterior, and two lateral angles. The upper 
or anterior sides are formed by the superior cerebellar peduncles, the lower or 
posterior sides by the inferior cerebellar peduncles, all of which overlap the floor 
a little. 
The Floor (Fig. 605).—The upper portion of the floor is furnished by the 
pons, the lower by the oblongata. In its whole extent the floor is cleft longi- 
tudinally by a median fissure, and a description of one half answers perfectly for 
the other. 
In the Pontile Portion.—Sloping down from the upper angle, parallel with 
and close to the superior peduncle is a strip of bluish hue, the locus ceruleus. In 
OCULO-MOTOR 
-TROCHLEAR 
TRIFACIAL 
"(upper root) 
•TRIFACIAL (motor ROOT) 
-ABDUCENT AND FACIAL 
-FACIAL 
-AUDITORY 
GLOSSOPHARYNGEAL 
HYPOGLOSSAL 
TRI FACI Al 
(lower root) 
GLOSSOPHA- 
~ RYNGEAL 
PNEUMO- 
- GASTRIC 
PNEUMOGASTRIC—- 
SPINAL ACCESSORY' 
Fig. 611.—Diagram of the motor nuclei in and near 
the floor of the fourth ventricle. (Testut.) 
Fig. 612—Diagram of the sensory nuclei in 
the floor of the fourth ventricle. (Testut.) 
line with this and below it at the lateral angle is a shallow depression, the fovea 
superior. Between the fovea and the middle line is a white tubercle, the eminentia 
teres. 
In the Ohlongatal Portion.—Below the eminentia teres and, like it, close to 
the median cleft, is another and larger white projection, forming a triangular ridge 
which extends nearly to the lower angle. It is the hypoglossal area. At the 
outer side of the last is the pneumogastric or vagus area, a gray, somewhat tri- 
angular space, the lowest part of which is slightly depressed, and is called the 
fovea inferior. Between the vagus area and the lateral angle is a white elevation, 
the auditory area, whose upper part is called the acoustic tubercle. Large white 
threads, the strive acusticce, pass outward from the mid-line, and are gathered into 
a bundle beneath the projecting restis, forming a root of the auditory nerve. At 
the lower angle is the obex. 
The Roof (Fig. 598).—The roof is formed above by the valvula, which 
stretches between the superior peduncles ; below by the metatela, which spans the 
space between the inferior peduncles. The lower edge of the valvula is continued 
downward and backward into a thin white layer, derived from the centre of the 
cerebellar vermis; and the upper border of the metatela is continuous with the 
pia and endyma, respectively covering and lining a similar layer which runs 
downward and backward from the white of the vermis. Thus, the roof is 
farthest from the floor, and forms a tent, at the point where these cerebellar 
laminae separate—the one to go up (forward) to the valvula, the other to go down 
(backward) to end by a free edge of nervous tissue, from which the roof is con- 552 
THE CEREBROSPINAL AXIS. 
tinned by a membrane of vascular and serous tissues. In the centre of this 
membrane is an aperture, the metapore, or 
foramen of Magendie. 
It is interesting and very important to 
observe (Figs. 611, 612) how large a part of the 
cranial nerves have their deep (real) origin in 
and close to the floor of the fourth ventricle. 
OBION 
GATA 
The average weight of the normal adult 
encephalon is in the region of 49 ounces for the 
male, and about five ounces less for the female. 
THE SPINAL CORD. 
CERVICAL EN- 
LARGEMENT 
The spinal cord (Fig. 613) is the terminal 
portion of the cerebro-spinal axis, and is a direct 
continuation of the oblongata, having its upper 
limit at the lowest level of the pyramidal decussa- 
tion. It is contained in the canal of the vertebral 
column. Like all other parts of the axis, it is 
bilaterally symmetrical. From it are given off 
almost all of the nerves which supply the volun- 
tary muscles of the parts below the head, and to 
it go the sensory nerves of the corresponding 
regions. 
Its shape approaches the cylindrical. It is 
slightly flattened ventro-dorsally, tapers at its 
caudal end, and presents a fusiform swelling in 
LUMBAR EN- 
LARGEMENT 
llterminal 
f CONE 
Fig. 613—Spinal cord, oblongata, and 
pons. Left-hand figure is ventral view, 
right-hand is dorsal. (Testut.) 
Fig. 614.—Sagittal section of the spinal canal, showing the 
lower end of the cord and thefilum terminale. The dura is seen 
extending to the third sacral vertebra. (Testut.) THE SPINAL CORD. 
553 
the cervical region, and another in the thoracico-lumbar region. The cervical 
enlargement extends from the third cervical vertebra to the second thoracic, and 
corresponds to the origin of the nerves of the upper limbs. The lumbar enlarge- 
ment, which marks the origin of the nerves of the lower limbs, begins at the 
ninth thoracic vertebra, attains its greatest size at the twelfth, and thence rapidly 
dwindles in a terminal cone, from the apex of which extends a delicate prolonga- 
tion, the filum terminate (“ the end thread ”), whose upper part presents the essen- 
tial histologic elements of the cord (Fig. 614). It is customary, however, to 
regard the tip of the cone as the distal end of the spinal cord, as the filum 
is plainly only a rudimentary structure. 
The cord presents two curves, which correspond to those of the parts of 
the column which it occupies : a cervical curve, with its convexity forward, and a 
thoracic curve, with its concavity forward. The cord proper extends from the 
plane of the occipito-atloid joint to that of the body of the second lumbar verte- 
bra, and the filum continues from this point to the base of the coccyx. The 
length of the cord proper is about eighteen inches, its transverse diameter one half- 
inch or less, and its weight nearly an ounce. 
Fissures and Columns.—External inspection of the cord shows upon its 
surface a number of creases, running from end to end. In the middle 
line in front is a deep cleft—the ventro-median fissure; in the middle line 
behind a shallow one—the dorso-median fissure; at each side of the latter, 
nearly a quarter of the way around to the front is a shallow dorso-lateral 
fissure ; and between the dorso-lateral and the dorso-median, and much nearer the 
latter, is the dorso-intermediate fissure. The dorso-lateral fissures are occupied by 
the dorsal roots of the spinal nerves. The ventral roots of the spinal nerves 
come off on each side from a vertical strip of the surface which is about as far 
from the ventro-median fissure as the dorsal roots are from the dorso-median 
fissure. Thus, each lateral half of the cord is divided into three parts : one 
between the ventro-median fissure and the ventral roots—the ventral (anterior) 
column; a second between the ventral roots and the dorsal roots—the lateral 
column; and a third between the dorsal roots (or dorso-lateral fissure) and the 
dorso-median fissure—the dorsal (posterior) column, which is subdivided by the 
dorso-intermediate fissure into the dorso-lateral column, and the dorso-mesial 
column. All of these structures are composed of white nervous tissue. 
The Gray Matter of the Cord (Fig. 615).—A transverse section of the cord 
shows a mass of gray nervous tissue, enclosed by the white. The gray of each 
side is somewhat crescentic in form, or the whole mass may perhaps be more 
aptly likened to two commas, one of which is reversed, the two placed back to 
back, and their convexities connected by a narrow band. The head of each 
comma is ventral, its tail dorsal. The two portions of each are called horns or 
cornua} The ventral horn points forward and outward, but does not come nearly 
to the margin. The free end of it is the head, the attached part is the base. 
From the head project numerous spine-like processes; from the concave side of 
the base juts out a triangular mass—the lateral horn, which is most pronounced 
in the upper thoracic region. The dorsal horn is directed backward and outward, 
and quite or nearly reaches the periphery of the cord at the dorso-lateral fissure. 
It is divided into three parts ; the base, which is continuous with that of the ven- 
tral horn ; the head, which ends behind in a point, called the apex ; and the neck, 
which connects the base and head. Near the hind part of the head is a crescentic 
portion, the substantia gelaiinosa (“ gelatinous substance ”). From the concavity 
of the comma, at the base of the dorsal horn, projects a network of gray tissue, 
enclosing in its meshes little masses of white. This is the processus reticularis 
1 The term horn or cornu employed generally to designate a portion of the gray matter of the 
cord is strictly adapted only for use in the description of transverse sections ; for it is manifest that 
the gray of the cord, equally with the white, is arranged in columnar masses. But, as practically we 
do not see the gray except in cross-sections, the word horn or cornu is sufficiently accurate and not 
misleading. 554 
THE CEREBROSPINAL AXIS. 
(“reticular process”), or reticula, and it is most marked in the upper cervical 
region. The base of the dorsal horn bulges toward the middle line of the cord, 
forming the column of Clarice, a structure found in the thoracic region and a little 
above and below it. The band connecting the two commas is the gray commissure, 
and it contains the central canal of the spinal cord, a minute channel, continuous 
with the fourth ventricle of the brain, from which it extends to the middle of the 
filum term inale. It is not patent in every part of its course. 
VENTRAL MEDIAN 
FISSURE 
v F 
VENTRAL ROOTS 
VENTRAL HORN- 
LATERAL HORN 
RETICULAR. 
FORMATION 
DORSAL HORN 
DO RSO - LATERAL 
FISSURE 
-DORSAL ROOTS 
DORSAL MEDIAN 
FISSURE 
Fig. 615.—Transverse section of the spinal cord at the middle of the thoracic region. (Testut, after Pierret.) 
The various fissures which have been mentioned are all seen to have little 
depth, excepting the ventro-median, which cuts far into the substance of the cord, 
and reaches almost to the gray commissure. Between the dorso-median fissure 
and the gray commissure is a septum of neuroglia, which separates the two dor- 
sal columns from each other. The ventral and lateral columns are continuous 
around the head of the ventral horn, and, on this account, it is not uncommon to 
speak of them as a single structure—the ventro-lateral column. The two ventral 
columns are connected in their deepest parts by the white commissure, which is in 
contact with the gray commissure. These facts are shown diagraramatically in 
the left half of Fig. 616. 
A knowledge of the obvious features which have been mentioned, while 
necessary for purposes of description, affords little practical help in the study of 
the physiology of the cord ; and, consequently, it is essential to know the delimi- 
tations of the paths by which motor impulses and sensory impressions are con- 
ducted to and fro in this organ of intermediation between the highest centres of the 
cerebrum and the most distant areas of the periphery. To a large extent these 
paths have been ascertained, and will now be indicated. It will be seen that 
there is little in the gross appearance of the cord to give information as to the 
boundaries of these cables of telegraphic communication. The right half of the 
diagram (Fig. 616) will aid in the understanding of the few succeeding paragraphs. 
The Conduction Paths of the Cord.—ln the ventral column a narrow triangular 
area is marked off next to the ventro-median fissure. This is the direct pyramidal 
tract—“ pyramidal,” because it is a downward extension of a part of the pyramid 
of the oblongata ; “ direct,” because this path is on the same side of the middle 
line in encephalon and in cord. It gradually diminishes in size from above 
downward, and disappears at the level of the root of the last lumbar nerve. THE SPINAL CORD. 
555 
At the back part of the lateral column, close to the dorsal horn, is an oval 
area, the crossed pyramidal tract—“ pyramidal,” for the reason just given; 
“crossed,” on account of the decussation which occurs in the oblongata. It 
dwindles as it descends, and ceases at the third or fourth sacral nerve-root. 
Between the outer side of the crossed pyramidal tract and the surface of the 
lateral column is the dorsal part of a long, narrow area, the direct cerebellar tract, 
so called because its fibres course upward through the oblongata as straight as 
possible to the cerebellum. It appears at the level of the eighth or ninth thoracic 
nerve-root, and progressively increases, as it ascends. 
VENTRAL 
COLUMN 
LATERAL 
COLUMN 
/CROSSED 
/ PYRAMIDAL 
TRACT / 
D O R S O- 
COLUMN 
/DORSO- 
MESIAL 
TRACT ' 
O F 
\ BURDACH 
DORSOLATERAL 
FISSURE 
I COLUMN 
TRACT 
OF 
GOLL 
POSITION OF 
ROOTS 
dorsointermediate/ 
FISSURE ' 
Fig. 616.—Diagrammatic ideal transverse section of the spinal cord. On the left side are shown the gross 
divisions; on the right side, the conduction paths. (F. H. G.) 
DORSAL 
FISSURE 
Anterior to this is a somewhat triangular area, which extends to, perhaps 
beyond, the place of exit of the ventral roots, the ascending lateral tract, or the 
Gowers tract—named “ascending,” from the direction in which it carries impres- 
sions ; “ lateral,” from its position. It occupies the whole length of the cord, 
and increases in size from below upward. 
Lodged in the curve of the gray comma, and penetrated by the interlocking 
strands of the reticula, where the latter exists, is the deep lateral association 
tract (otherwise known as the mixed lateral). The first and second words in this 
title are self-explanatory ; the third is chosen because it is descriptive of the 
function of the fibres composing this tract. These fibres originate in cells ot the 
gray substance of the cord, run a short course, then turn into the gray, and end 
in arborizations around its cells. Thus, they act as longitudinal commissures, 
associating each part of the cord with parts a short distance above and below. 
The remaining areas in the ventral and lateral columns are perfectly con- 556 
THE CEREBROSPINAL AXIS. 
tinuous around the head of the ventral horn, except for the interruption occa- 
sioned by the passage of the ventral roots from the surface to the ventral horn. 
They are often called the fundamental tracts, or ground tracts of their respective 
columns ; but a simpler and more instructive name is the ventro-lateral associa- 
tion tract—an appellation which indicates at once the location and the service of 
the structure, whose function is to connect parts of the cord situated at different 
levels. The association tracts are found in the whole length of the cord, and are 
subject to but slight variations of size. 
In the dorsal column are two tracts, separated from each other by a line run- 
ning from the dorso-intermediate fissure to a point near the junction of the 
neurogliar septum and the gray commissure. These tracts, then, correspond 
exactly to the dorso-mesial and the dorso-lateral columns, and are called respec- 
PONa 
UPPER 
CERVICAL 
VENTRAL PLANE 
‘ OF OBLONGATA 
.MIDDLE PLANE 
OF OBLONGATA 
,DORSAL PLANE 
OF OBLONGATA 
CERVICAL EN- 
LARGEMENT 
{longitudinal 
{COMMISSURAL 
THORACIC 
LUMBAR EN- 
LARGEMENT 
Fig. 617.—Diagram to show the crossing of the pyramids 
(red) and of the lemniscus (blue). (Testut.) 
Fig. 618.—Transverse sections of 
the spinal cord at different levels. 
(Testut, after Erb.) 
tively the tract (or column) of Golf and the tract (or column) of Burdach. The 
Goll tract increases in size as it ascends; the Burdach tract varies but little from 
its average at different levels. 
Finally, at the dorso-lateral fissure is a small irregular area, the marginal 
bundle, called also by the names of the men who simultaneously described it, the 
Sp itzka—L issauer tract. THE MEMBRANES. 
557 
From what has been said it must be evident that the size and shape of the 
cord, and the absolute and relative amounts of white and gray matter vary 
greatly in different parts. This is shown 
pictorially in Fig. 618. 
The Spinal Nerve-roots (Fig. 619).— 
The roots of the nerves which arise from 
the spinal cord are in two sets, dorsal and 
ventral. The dorsal leave the cord in a 
continuous series at the dorso-lateral fis- 
sure, the ventral along a narrow vertical 
strip of the surface nearest to the head of 
the ventral horn. At fairly regular in- 
tervals the roots in each series are bunched 
together, and then the fagot of the dorsal 
set is united to that of the ventral, the 
result being a single bundle, which is a 
spinal nerve. In this nerve the fibres 
from the two roots are intimately mingled, 
and thus the spinal nerves are mixed 
nerves. On the dorsal bundle of each 
nerve is a ganglion, situated at the distal 
part of the root and outside of the sheath 
of dura. The upper roots are short and 
horizontal, and those below these are pro- 
gressively longer and more nearly per- 
LIG. 
j 
thoracic/ 
DORSAL 
ROOTS 
"DURA 
LUMBAR 
■‘VENTRAL 
ROOTS 
SACRAL' 
CO COY-1 * 
GEAL 
FILUM 
Fig. 619—Formation of a spinal nerve, 
(Testut.) 
Fig. 620.—Lower end of the spinal cord and the 
cauda equina, dorsal aspect. The dorsal roots of the 
right side have been removed. (Testut.) 
pendicular. The lowest come off from the tapering cone at the end of the cord 
proper, are very long and perpendicular in direction. From its resemblance to a 
horse’s tail the collection of these roots is called the cauda equina (Fig. 620). 
THE MEMBRANES 
of the Cerebro-spinal Axis. 
The brain and spinal cord are enveloped in three membranes {meninges), of 
which the innermost is called the pia, the middle one the arachnoid, and the outer- 
most the dura. Each of these is a covering for every part of the axis ; but they have 
such variations of structure and arrangement in different parts as to make it best 
to consider separately the membranes of the brain and those of the spinal cord. 558 
THE CEREBROSPINAL AXIS. 
The Membranes of the Brain. 
The Dura, formerly called dura mater (“severe mother”), is a strong, thick 
membrane, composed of white fibrous tissue with a small admixture of yellow 
fibres, and lodging a great number of blood-vessels. It is arranged in two layers, 
which are closely united in most parts, the outer one being decidedly the more 
vascular. Externally the dura is firmly adherent to the inner surface of the 
bones which form the brain-case, and is for them the internal periosteum, known 
as endocranium (“ within the cranium When the dura is peeled off from the 
bones its outer surface is seen to be flocculent, owing to the vessels which pass 
from it into the bone being pulled partly out of the channels in which they were 
lodged, and torn off, and to the similar treatment of certain small, fibrous pro- 
cesses of the membrane. The endocranium is continuous with the pericranium at 
the margin of the various holes which perforate the skull. The dura extends 
outward through the basal foramina, and becomes continuous with the areolar 
sheath of the nerves which pass through them. 
Several broad prolongations of the dura extend from the periphery toward 
the centre of the cavity of the brain-case. In their formation the inner layer of 
CIRCULAR 
SINUS 
CAVERNOUS 
SINUS 
SUPERIOR PETRO 
SAL SINUS 
STRAIGHT 
SINUS / 
•lateral 
SINUS 
Fig. 621—The tentorium, viewed from above. (Testut.) 
the dura separates from the outer along a definite line and projects centrally. 
Presently it comes in contact with a corresponding and opposite plate, which has 
been formed in the same manner, and the two blend, and, thus united, stretch 
toward the centre as a strong, partial partition. At the attached border of these 
shelf-like structures is left a prisraoid space, whose base is bounded by the outer 
layer of the dura, and its sides by the prolongations from the inner layer. These 
spaces are lined by an extension from the tunica intima of the veins, and thus 
constitute the venous sinuses, already described. THE MEMBRANES. 
559 
The principal processes of the dura are the tentorium, the falx cerebri, and 
the falx cerebelli. 
The tentorium (“ tent ”) springs from the borders of the superior petrosal and 
the horizontal part of the lateral sinuses. From this origin it rises toward the 
centre, and terminates in a free border, which extends forward and is attached on 
each side to the anterior and posterior clinoid processes. There is thus left a 
large opening, in which is situated the mesencephalon. The tentorium is spread 
between the cerebellum and the occipital portion of the cerebrum, protecting the 
former from the superincumbent pressure of the latter. 
The falx cerebri {“ sickle of the brain ”) is so called from its shape. It is 
attached anteriorly to the crista galli, posteriorly to the median part of the upper 
Fig. 622.—Falx cerebri and tentorium, left lateral view. (Testut.) 
surface of the tentorium, and for the rest of its extent to the ridges bounding the 
great longitudinal sinus. It dips into the great fissure between the hemispheres, 
deeply behind, and progressively less so as it is traced to the front. It thus 
forms a tightly stretched, median septum, which prevents the pressure of one 
hemisphere upon the other in the lateral movements of the head, just as the fore- 
and-aft partition in a vessel keeps the cargo from shifting from side to side in the 
lurchings of the craft at sea. The falx cerebri encloses the superior longitudinal 
sinus peripherally, the straight sinus in its tentorial attachment, and the inferior 
longitudinal sinus in its free border. 
The falx cerebelli is a small median septum between the cerebellar hemi- 
spheres behind. It is broadest above, where it is attached to the under surface 
of the tentorium, and tapers rapidly as it descends. It encloses the occipital 
sinus in its posterior border. 
Under the names of diaphragm of the sella and tentorium of the hypophysis a 
small double fold of the dura extends inward from all sides over the sella tur- 
cica, covering the hypophysis, and leaving a little aperture for the apex of the 560 
THE CEREBROSPINAL AXIS. 
infundibulum. The presence of this fold accounts for the fact that the hypo- 
physis is usually torn away when the brain is removed. 
The arteries of the dura are branches of the occipital, vertebral, ascending 
pharyngeal, internal maxillary, internal carotid, and ophthalmic. 
The Pia, formerly called pia mater affectionate mother”), consists of blood- 
vessels arranged in the form of a membrane, and supported by areolar tissue. 
It is the nourishing tunic of the brain, and lies close to its surface everywhere, 
dipping down to the bottom of every fissure, and sending the branches of its 
arteries into the nervous substance. It is prolonged onto the roots of the nerves, 
and becomes continuous with their connective-tissue sheath. The velum inter- 
position and choroid plexuses, already described, are pial structures. 
The Arachnoid (“ like a spider’s web ”) is a thin, delicate membrane, situated 
between the pia and the dura, much nearer the latter, and, for the most part, sub- 
stantially parallel with it. It does not follow the pia into the fissures, except the 
great longitudinal. The external surface of the arachnoid is furnished with a 
FALX CEREBRI 
DURA" 
Fig. 623.—The arachnoid at the base of the brain. The membrane has been peeled off from the left hemf 
sphere. (Testut.) 
single layer of flattened epithelial cells, which is continuous with the lamina of 
similar cells on the inner surface of the dura. Between them is a little serous 
fluid. Thus we have the elements of a serous membrane, and it is proper to con- 
sider the arachnoid such. The interval between the dura and the arachnoid is 
the subdural space or arachnoid cavity. It is crossed obliquely by little fibrous 
bundles, which connect the two membranes. The cavity is normally merely 
virtual, its opposite sides being in contact; but it may become actual in disease. 
The under surface of the arachnoid is connected with the outer surface of the 561 
THE MEMBRANES. 
pia by numberless trabeculae of fibrous tissue, which form a delicate network. 
In some situations these are very abundant, in others much less so; but every- 
where they are covered with flattened epithelial cells. The interval between the 
arachnoid and the pia is the subarachnoid space. It is essentially lymphatic in 
character, and contains cerebro-spinal fluid. At certain places the subarachnoid 
space is quite deep, and the trabeculae are comparatively few. Such enlargements 
are known as cisternce arachnoidales (“ arachnoid reservoirs ”). The mctapore (for- 
amen of Magendie) in the roof of the fourth ventricle permits a communication 
between the ventricular cavity and the subarachnoid space. At irregular inter- 
vals, principally near the longitudinal sinus, the arachnoid buds out into tufts, 
which press upon the structures peripheral to themselves, and even produce 
marked pits in the inner table of the bones. These bodies are called glandulce 
Pacchionii (“ little glands of Pacchioni ”). Sometimes they contain minute, hard 
particles, called brain-sand. 
The Membranes of the Spinal Cord. 
In considering the meninges which enclose the cord it will be sufficient to 
indicate the characteristics in which they are unlike the corresponding structures 
in the head. 
The Dura.—The feature in which the dura of the cord differs most strikingly 
from that of the brain is in its not being the internal periosteum of the bones of 
the cavity in which it is contained. Each of the segments of the vertebral column 
has its own periosteum. The dura is reflected from the brain-case at the margin 
of the foramen magnum, and below this hangs as a long tube {theca, “case”) 
between the periphery of the spinal canal and the surface of the spinal cord, 
having attachments to the upper three cervical vertebrae and low down to the 
posterior common ligament. Be- 
tween the dura and the vertebrae 
is the epidural (“ upon the dura”) 
space occupied by areolar tissue, 
in whose meshes are many fat- 
cells and a plexus of spinal veins. 
The outer, as well as the inner 
surface, is furnished with a single 
layer of epithelial cells. 
The Pia is more fibrous and 
less vascular than that of the en- 
cephalon. From each side ex- 
tends a long ribbon of connective 
tissue, the outer edge of which is 
marked by long, shallow notches 
CAUDA EQUINA; 
* FI LU M 
. -DURA 
FIFTH LUMBAR 
“WJ NERVE 
DURA 
GANGLION OF 
DORSAL ROOT 
.ARACHNOID 
DORSAL 
/ ROOT 
.VENTRAL 
/ ROOT 
‘'••-FIFTH SACRAL 
S NERVE 
-COCCYGEAL 
dura 
Fig. 624.—Pouch at lower end of spinal dura, and the 
sacral nerves. (Testut.) 
Fig. 625.—Horizontal section of vertebral 
column, showing spinal cord and its mem- 
branes. (Gegenbaur.) 562 
THE CEREBROSPINAL AXIS. 
and intervening sharp projections. From the appearance thus produced this 
structure has been called the ligamentum denticulatum (“toothed ligament”). 
The projections are attached to the dura between the places where the spinal 
nerves perforate that membrane. 
The Arachnoid lies near the dura and far from the cord, and, consequently, the 
subdural space is small and the subarachnoid is large. The latter space has few 
trabeculae as compared with that of the brain; but a dorsal median partition, the 
septum posterius, passes from the arachnoid to the pia, giving passage to vessels. 
The space is crossed also by the ligamenta denticulata. THE NERVES. 
W. KEILLEB. 
IN this chapter will be described, first, the nerves which connect the brain and 
spinal cord with the skin, muscles, and viscera, and the nuclei in which these 
nerves take origin; and, second, the sympathetic system. The mode in which 
the nerves end in skin, muscles, and other organs is dealt with in the chapter on 
histology, or in the sections of the work describing the organs themselves. 
THE CEREBRO-SPINAL NERVES. 
The cerebrospinal nerves are those which spring directly from the brain or 
spinal cord. Those which pass to their destination through foramina in the base of 
the skull are called cranial nerves. The rest are called spinal nerves, as they spring 
from the sides of the spinal cord and emerge through the intervertebral foramina, 
excepting the last spinal or coccygeal nerve, which passes through the lower 
extremity of the neural canal. The first spinal nerve, however, is somewhat 
exceptional, arising from the oblongata, and emerging from the neural canal 
between the occipital bone and the atlas. All these nerves are paired and 
symmetrically distributed, the apparent asymmetry of the vagus being due to 
developmental changes. As the nerves leave the brain or cord and pierce the 
membranes, they receive investments from the pia, arachnoid, and dura, which 
blend with the epi- and perineurium; but fluid, injected forcibly into the sub- 
arachnoid or subdural space, will find its way readily along the nerves for some 
distance. In the case of the optic nerve each sheath remains distinct as far as 
the eyeball. 
Typical Constitution of a Cerebrospinal Nerve.—All spinal nerves and most 
cranial nerves are mixed; that is, are both motor and sensory in function, the 
function of each fibre depending on its mode of origin and termination ; and, 
since cranial nerves, though sometimes obscurely, follow the same plan of forma- 
tion as spinal nerves, we shall take the latter as the type for study. 
The diagrammatic representation of a spinal nerve in Fig. 626 shows that it 
arises by two roots from the spinal cord. The dorsal root is sensory, has a gan- 
glion on it, and springs by one compact bundle from the dorsal horn of gray 
matter and dorso-lateral aspect of the cord. The ventral root is motor, has no 
ganglion, and springs by several bundles from the ventral horn of gray matter 
and the ventral aspect of the cord. The points by which these several bundles 
leave the cord form collectively the superficial origin of the nerve. Each fibre 
of the motor root is the axis-cylinder process of one of the nerve-cells of the 
ventral horn of gray matter, the finer branching processes of this cell connecting 
it with higher centres. While the nerve-cell lives, the fibre lives ; when the cell 
dies the fibre dies. These cells of the ventral horn form collectively the deep or 
nuclear origin of the motor root, which their axis-cylinder processes unite to 
form. 
The ganglion on the dorsal root contains the cells whose axis-cylinder pro- 
cesses form the sensory segment of the nerve. Though separated from the spinal 
563 564 
THE NERVES. 
cord in the adult, it is an outgrowth from it in the embryo. The cells of this 
ganglion are bipolar, sending one process centrifugally into the nerve-trunk, and 
the other centripetally into the spinal cord. The latter bifurcates, one branch 
Fig. 626.—Diagram, to explain the formation and connections of a spinal nerve. Motor tracts are red, sen- 
sory blue. A circle with a central dot indicates where the nerve takes a vertical direction. The presence of 
descending fibres in the lateral tract is to be noted. (W. Keiller.) 
descending in the cord to enter into relationship with the cells of the dorsal horn 
of gray matter, and the other ascending to form branching processes round the THE CRANIAL NERVES. 
565 
cells of Clarke’s column, and of the nucleus gracilis and nucleus cuneatus in the 
oblongata, and others which need not be mentioned. 
Thus a dorsal nerve-root is related to two groups of cells, viz., those of its 
ganglion and a number of widely scattered cells of the gray matter of the spinal 
cord and oblongata. The ganglion is homologous with the Gasserian ganglion 
on the fifth cranial nerve, the jugular ganglion on the ninth, the ganglia of the 
tenth, and the nerve-cells of the olfactory bulb, retina, and spiral ganglion of 
the cochlea; and the cells of the dorsal horn of gray matter, with which the 
sensory fibres are related, collectively represent what are described as the sensory 
nuclei of the cranial nerves. 
The mixed cranial nerves, such as the fifth, ninth, and tenth, follow this type 
very closely; the third, fourth, sixth, seventh, eleventh, and twelfth are purely 
motor nerves, and correspond developmentally with the motor root of a spinal 
nerve ; while the first, second, and eighth are purely sensory, and are constituted 
like the sensory root of a spinal nerve. 
THE CRANIAL NERVES. 
The classification of the cranial nerves into twelve pairs is based upon their 
mode of distribution. It was proposed by Soemmering, and is now generally 
adopted, in preference to the older classification of Willis into nine pairs, which 
had reference to their mode of piercing the dura. The following table gives at 
a glance the numerical and the ordinary name of each nerve, and a summary of 
its function and area of distribution. 
Table of the Cranial Nerves. 
Classification 
of Soemmering. 
Other Names. 
Distribution. 
Function. 
First. 
Olfactory. 
Upper third of nasal cavity. 
Special Sense (Smell). 
Second. 
Optic. 
Retina. 
Special Sense (Sight). 
Third. 
Oculomotor. 
Muscles of eyeball (except external rectus 
and superior oblique). 
Motor. 
Fourth. 
Trochlear. 
Superior oblique of eyeball. 
Motor. 
Fifth. 
Trifacial. 
Sensory part to face, fore part of scalp, ex- 
ternal ear, eye, teeth, gums, cheek, fore 
part of tongue. Motor part to muscles 
of mastication. 
Ordinary Sense. 
Motor. 
Sixth. 
Abducent. 
External rectus of eyeball. 
Motor. 
Seventh. 
Facial. 
Superficial muscles of face, frontalis, pla- 
tysraa, stylohyoid, and posterior belly 
of digastric. 
Motor. 
Fighth. 
Auditory. 
Membranous labyrinth of ear. 
Special Sense (Hearing 
and Equilibrium). 
Ninth. 
Glossopharyn- 
geal. 
Pharynx and hind part of tongue, some 
motor fibres. 
Special Sense (Taste). 
Ordinary Sense. 
Motor. 
Tenth. 
Pneumogas- 
trie, or 
vagus. 
Sensory to external ear. Motor and sensory 
to pharynx, larynx, trachea, lungs, 
oesophagus, stomach, heart. Some fibres 
to liver. 
Ordinary Sense. 
Motor. 
Eleventh. 
Spinal acces- 
sory. 
Motor to trapezius and sternomastoid mus- 
cles. The rest is accessory to the pneu- 
mogastric. 
Motor. 
Ordinary Sense. 
Twelfth. 
Hypoglossal. 
Muscles of the tongue. 
Motor. 
Superficial Origins (Fig. 627).— file cranial nerves spring from the under sur- 
face of the brain in the order of their names. Thus, the first appears in front of 
the anterior perforated spot; the second springs from the chiasma, the optic tracts 
being superficially traceable to the corpora qnadrigemina; the third nerve arises 
from the inner side of the crus cerebri close to the pons; the fourth winds round 566 
THE NERVES. 
the outer side of the pons, and can be traced dorsally to the valvnla, whence it 
emerges. The fifth arises by two bundles from the side of the pons, the smaller 
motor root being in front of and ventral to the larger sensory root. The sixth 
springs from the groove between the pons and anterior pyramid, the seventh and 
eighth from the same groove bnt more laterally. A small bundle between theseventh 
and eighth, called the pars intermedia, furnishes an additional root to the seventh. 
The ninth, tenth, and eleventh arise as a series of small bundles from the side of 
the oblongata in a vertical line, dividing the restiform body from the olive and 
lateral column of the cord. The spinal portion of the spinal accessory emerges 
by numerous bundles from the side of the cord in a direct line with the rest of 
this group, extending as far down as the fifth, sixth, or even seventh cervical nerve. 
The twelfth nerve springs by ten or twelve small bundles from the groove 
between the olivary body and anterior pyramid, and thus lies ventral to the pre- 
GENU OF 
CALLOSUM 
SYLVIAN 
'FISSURE 
ANTERIOR PER- 
FORATED SPACE 
.INFUNDI- 
BULUM 
.POSTERIOR PER- 
FORATED SPACE 
..CRUS CEREBRI 
MIDDLE CEREBEL- 
LAR PEDUNCLE 
-OBLONGATA 
—CEREBELLUM 
Fig. 627.—Under surface of the brain, showing the superficial origins of the cranial nerves The Roman 
numerals indicate the nerves. (Testut.) u -tumian 
ceding series, and nearer the pons than the last of them. It lies in series with 
the anterior roots of the first spinal nerves. 
Deep or Nuclear Origins of the Cranial Nerves.—Like the spinal nerves the 
cranial nerve-roots can be traced till they come into close relationship with cer- 
tain groups of cells, which, for anatomical and physiological reasons, we regard as 
their deep origins. It is impossible for the student to study this subject till he 
has thoroughly mastered the anatomy of the brain and especially of the oblongata 
and pons; but, when he has learned the gross anatomy of the central nervous 
system, he will find much living interest in what is now known of this obscure 
but vitally important section. THE OLFA CTOB Y NEB VE. 
567 
Deep Origin of the First or Olfactory Nerve.—When we speak of the first or 
olfactory (“ smelling ”) nerve, we usually mean the olfactory tract with its three 
roots and terminal bulb, and regard the twenty or more filaments, which spring 
from the bulb, as branches of the nerve. Embryology teaches us, however, that 
the tract is really a hollow outgrowth of the lateral ventricle, that the cells in the 
inferior segment of the bulb are homologous with the nucleus of a sensory nerve, 
and that the filaments which pierce the cribriform plate collectively represent the 
sensory nerve itself. 
The olfactory tract is a flattened band which lies in the olfactory fissure on the 
orbital surface of the frontal lobe. On its under surface it is flat and lies on the 
olfactory groove of the sphenoid; superiorly it presents a ridge which fits into 
the olfactory fissure. Posteriorly it springs from the cerebral cortex in front of 
the anterior perforated space by three roots; anteriorly it ends in the olfactory 
bulb. Microscopically the tract presents on transverse section, (a) a thin, gray 
cortex, continuous Avith the cortex cerebri; (6) an inner layer of raedullated 
nerve-fibres, thick inferiorly and thinning off above; and (c) some central 
gray substance consisting of neuroglia and fibrous tissue—the remains of the 
ependyma of the embryonic ventricular cavity, Avhich in adult man is 
obliterated. 
The internal or mesial root is a band of medullated nerve-fibres, running into 
the great longitudinal fissure, it is lost in the anterior end of the callosal 
gyrus. 
The external or lateral root, larger than the internal, is a white band Avhich 
crosses backward and outward over the anterior perforated space toward the 
extremity of the temporal lobe, Avhere it ends in the hippocampal gyrus and per- 
haps the amygdala. 
The middle or gray root is best called the trigonum olfactorium, being only 
a slight elevation in the angle betAveen the tAvo roots just mentioned, and con- 
taining no non-medullated band of fibres which could properly be called a gray 
root. 
The olfactory bulb is oval in shape, about tAvo-fifths of an inch long and a 
third as broad. Its upper surface presents a ridge continuous Avith the ridge of 
the olfactory tract, and like it received into the olfactory fissure of the frontal lobe. 
Its under surface is slightly convex, and lies on the cribriform plate of the eth- 
moid, and from it spring the tAventy or more filaments which collectively form the 
olfactory nerve. The dorsal portion of the bulb consists of medullated nerve- 
fibres ; its A'entral segment contains the nerve-cells, Avhose axis-cylinder processes 
form the medullated nerves of the tract, and Avhose branching processes come into 
close relationship in the olfactory glomeruli with the branching ends of the 
olfactory filaments. These cells, therefore, form the nucleus of the olfactory 
nerve. 
It will be convenient here to complete the description of the olfactory 
nerve. 
The Olfactory Nerve (Figs. 628, 629). 
This nerve is represented by the twenty or more fine bundles of non-medul- 
lated fibres, Avhich spring from the under surface of the olfactory bulb. They 
pierce the foramina in the cribriform plate of the ethmoid bone, each receiving 
an investment of dura. Those piercing the inner line of foramina supply the 
upper third of the nasal septum (Fig. 628); the outer group supplies the lateral Avail 
of the nose as loav as the loAver border of the superior turbinated bone (Fig. 629). 
The fibres communicate freely, forming a fine network. They commence as 
axis-cylinder processes of the olfactory cells of the Schneiderian membrane, 
and terminate by minutely branching processes in the glomeruli of the olfactory 
bulb. 568 
THE NERVES. 
SEPTAL BRANCHES 
OF OLFACTORY 
--NASAL 
SEPTAL BRANCH] 
OF SUPERIOR V 
NASAL ) 
ANTERIOR 
PALATIN E 
Fig. 628.~Nasal septum, showing olfactory nerves and nerves of common sensation. (Testut.) 
s MECKEL’S 
’(/ GANGLION 
NASAL 
CUTANEOUS) 
BRANCHES f- 
OF NASAL )/ 
...SUPERIOR MAXILLARY NERVE 
...VIDIAN 
BRANCH 
L_ POSTERIOR PALATINE 
ILEXTERNAL PALATINE 
L-eustachian tube 
INFERIOR NASAL BRANCHES 
ANTFPinP Dfll ATIMP 
Sp-SOFT PALATE 
Fig. 629.—Outer wall of nose, showing olfactory nerves and nerves of common sensation. (Testut.) 
PALATINE 
The Second or Optic Nerve. 
Traced backward from the eyeball the optic (“ seeing”) nerves (Fig. 630) are 
seen to meet on the under surface of the brain in the optic commissure or chiasma, 
where they partially decussate, and whence two flattened bands, the optic tracts, 
pass backward round the crura cerebri to the thalami and quadrigeminal bodies. 
The optic tract (Fig. 630) arises by two roots from the pulvinar of the optic 
thalamus, the corpora geniculata, and the superior quadrigeminal body. Thence 
it bends round the upper end of the crus cerebri to which it is attached as a flat- 
tened, white band, and becoming more rounded, passes between the anterior per- 
forated space and the interpeduncular space to end in the chiasma. 
The optic commissure or chiasma (“ like X ”) is oblong, the longest diameter 
being transverse. It rests on a groove above the olivary eminence of the sphe- 
noid and has the internal carotid artery on either side of it. From its extrem- 
ities in front spring the optic nerves. 
The optic nerve enters the orbit by the optic foramen, accompanied by the 
ophthalmic artery, which lies below and external to it. In the orbit it 
runs forward, outward, and a little downward to the back of the eyeball, THE SECOND OR OPTIC NERVE. 
569 
which it pierces one-eighth inch to the inner side of the optic axis. Its fibres 
then radiate in all directions over the anterior surface of the retina. As the 
nerve enters the orbit it receives an investment from the dura, which sends a 
layer also to blend with the periosteum. The pial, arachnoid, and dural sheaths 
remain distinct as far as the sclerotic, with which they blend, and well-marked 
subdural and subarachnoid spaces can be demonstrated. In the orbit the nerve 
is closely surrounded posteriorly by the recti muscles; but farther forward is 
separated from them by fatty tissue. The ciliary vessels and nerves surround it, 
especially above and below, the ophthalmic artery and nasal nerve cross over it 
OPTIC NERVE 
CH I ASM A 
.ANTERIOR PER- 
FORATED SPOT 
OPTIC TRACT 
OUTER ROOT 
INNER ROOT 
EXTERNAL GENIC- 
ULATE BODY 
INTERNAL GENIC 
POSTERIOR BRACHIUM 
OPTIC THALAMUS 
ULATE BODY 
TESTIS 
PULVINAR 
N ATI S 
SPLENIUM OF CORPUS 
CALLOSUM 
Fig. 680.—Origin and relations of optic tract. Part of the base of the brain: temporal gyri drawn aside, 
pia removed. (W. Keiller.) 
from without inward, and the ciliary ganglion lies on its outer surface. It is 
pierced by the arteria centralis retinge and its vein. 
In the chiasma (Fig. 631) a partial decussation takes place. The outer fibres 
do not decussate, but connect the outer half of the retina with the geniculate and 
quadrigeminal bodies of the same side; the inner fibres decussate completely, 
connecting the inner half of the retina with these nuclei on the opposite side. 
Thus, the right optic tract conveys fibres from the right halves of both retinas to 
the right side of the brain, and the left behaves similarly. The lateral portions 
of the chiasma consist of uncrossed fibres, the central portion contains inter- 
crossed fibres from the nasal (inner) sides of both retinae. Besides these the 
posterior part of the chiasma is occupied by a band of fibres which, after partial 
interruption in the cells of the internal geniculate bodies, unite the inferior 
corpora quadrigemina with each other. This is called Gudden’s commissure, and 
appears to have nothing to do with sight. 
The fibres of the optic nerve commence as axis-cylinder processes of the large 
ganglionic cells of the retina, and end in branching processes round the cells of 
the external geniculate body, superior quadrigeminal body, and optic thalamus, 
which cells, therefore, form the nucleus of the optic nerve; thence fibres pass by 
the optic radiation to the cuneus in the occipital lobe of the cerebrum. Imper- 
fectly traced connections exist between the visual centres and the nuclei of the 
third, fourth, and sixth nerves. 
General View of the Nuclei of the Third to the Twelfth Cranial Nerves (Figs. 
632, 633).—The nuclei of the third to the twelfth cranial nerves inclusive lie 
in the central gray matter of the brain from the level of the posterior commissure 
to that of the decussation of the pyramids, the nucleus of the spinal accessory, 570 
THE NERVES. 
and the ascending vago-glossopharyngeal and fifth roots extending still lower 
down. In Fig. 632 the motor nuclei are represented (in red), in Fig. 633 the 
LEFT EYE 
RIGHT 
EYE 
'MACULA LUTEA 
UNCROSSED FIBRES 
OF LEFT RETINA TO 
FROM LEFT HALF 
LEFT CENTRES 
CHIASMA 
CROSSED FIBRES FROM LEFT HALF 
OF RIGHT RETINA TO LEFT CEN- 
TRES 
INTERNAL GENICULATE BODY 
NERVE CELLS 
EXTERNAL GENICULATE BODY 
AND ITS NERVE CELLS 
CONNECTING LEFT SIDE OF BRAIN 
WITH LEFT HALF OF RETINA AND 
CONSEQUENTLY RIGHT HALF OF 
FIELD OF VISION 
POSTERIOR aUADRIGEMINA 
OPTIC RADIATION 
Fig. 631.—Diagram of the course of the optic fibres. (W. Keiller, after Testut.) 
sensory nuclei (in blue). The motor nuclei are arranged in two interrupted 
columns, the third, fourth, sixth, and twelfth motor nuclei forming one column 
close to the middle line, and very near the floor of the aqueduct, fourth ventricle 
or central canal; while the motor nuclei of the fifth, seventh, ninth, tenth, 
and eleventh form another column, more deeply and more laterally situated than 
the first and deviating somewhat toward the side above, where the ventricle is 
widest. The fifth nerve has a well-marked ascending root, which is probably 
motor, as well as a crossed motor root. The spinal portion of the spinal accessory 
arises from the cells of the ventral horn of gray matter as low as the sixth or 
seventh cervical nerve. 
Coming now to the sensory nuclei, each sensory nerve has an ascending root. 
Thus the fifth, eighth, ninth, tenth, and accessory portion of the eleventh have 
each an ascending root which appears to bring it into relation with the nucleus of 
the funiculus cuneatus and gelatinous substance of Rolando (compare the con- 
nection of the sensory roots of the spinal nerves with the same nuclei). Each 
nerve has in addition a special sensory nucleus—the eighth nucleus is divisible 
into three groups—near the level of its point of exit and dorso-lateral to the 
motor nuclei. 
In longitudinal extent the nucleus of the third nerve occupies the floor of the 
aqueduct from the posterior commissure to the groove between the superior and 
inferior quadrigeminal bodies, the nucleus of the fourth lies ventrally to the testis, 
the fifth nucleus nearly corresponds to the lateral recess, the sixth lies under the 
eminentia teres, the eighth nuclei are on a level with the striae acusticae, and the THE THIRD OR OCULO-MOTOR NERVE. 
571 
seventh on the same level, but more mesial. Lastly the ninth, tenth, and 
eleventh form two columns (sensory and motor), and the twelfth a third column, 
which extend almost the whole length of the oblongata. 
OCULO-MOTOR 
■TROCHLEAR 
TRIFACIAL 
(upper root) 
■TRIFACIAL (MOTOR ROOT) 
■ABDUCENT AND FACIAL 
FACIAL 
-AUDITORY 
GLOSSOPHARYNGEAL 
GLOSSOPHA- 
— RYNGEAL 
PNEUMO- 
— GASTRIC 
HYPOGLOSSAL 
TRIFACIAI 
(lower root) 
PNEUMOGASTRIC* 
SPINAL ACCESSORY A 
Fig. 632.—Diagram of the motor nuclei in and near 
the floor of the fourth ventricle. (Testut.) 
Fig. 633.—Diagram of the sensory nuclei in 
the floor of the fourth ventricle. (Testut.) 
Connections of the Nuclei of the Ceanial Neeves with the Coe- 
ten Ceeebei. 
The cortical connections of the olfactory and optic nerves have already been 
described. The motor tract for the other cranial nerves seems to run from the 
motor area of the cerebral cortex, down through the genu of the internal capsule, 
pyramidal segment (middle third of the crusta) of the crus cerebri, and pyra- 
midal tract of the pons and medulla to nearly opposite their respective nuclei. It 
then crosses through the raphe and passes the forraatio reticularis to the motor 
nuclei of the opposite side. Round the cells of the motor nuclei the pyramidal 
fibres end, and from these cells fresh fibres pass by the motor nerve-roots to the 
periphery. The cortical centre for the facial occupies the lower ends of the 
precentral and postcentral gyri; the hypoglossal centre is in the lower end of 
the procentral and posterior end of the inferior frontal gyri. 
The sensory tract is less known but, on leaving the sensory nuclei, it appears 
to cross to the opposite fillet, and thus pass to the superior quadrigeminal body 
and subthalamic region or thalamus, some part of it going through the posterior 
third of the hind limb of the internal capsule to the cortex cerebri behind the 
motor area. 
The course of the nerve-roots from their nuclei to superficial origins is as follows : 
The roots of the third, fifth, sixth, eighth, twelfth, and the sensory roots of the 
ninth, tenth, and eleventh, run in nearly straight lines ventro-laterally from 
nucleus to point of superficial emergence. The fourth is altogether exceptional 
(see special description). The motor roots of the seventh, ninth, tenth, and 
eleventh run at first dorso-mesially toward the floor of the ventricle and then 
bend outward, and lastly ventrally to join the sensory roots, the seventh running 
upward for some distance before it turns outward. 
We now pass to a particular description of the cranial nerves from the third to 
the twelfth, inclusive of both. The first and second nerves have already been fully 
considered. 
The Third or Ocalo-motor Nerve. 
The nucleus of the third nerve (Fig. 635), the oculo-motor (“ eye-mover ”), 
consists of several distinct groups of cells, lying on the floor of the aqueduct, 572 
THE NERVES. 
close to the middle line, and nearly corresponding in position to the superior 
quadrigeminal body. It is just dorsal to the posterior longitudinal fasciculus, 
which appears to connect it with the nuclei of the seventh and eighth, and with the 
sixth nucleus of the opposite side. From its nucleus the nerve issues in many 
small bundles, running ventrally through the posterior longitudinal bundle and 
red nucleus to the oculo-motor groove, on the inner side of the crus cerebri just 
above the pons. The nuclei of both sides communicate freely. The nerve so 
formed passes between the posterior cerebral and superior cerebellar arteries, 
forward and a little outward, piercing the dura on the outer side of the poste- 
rior clinoid process, and so entering the outer wall of the cavernous sinus, in 
INTERNAL CAROTID ARTERY 
AND SIXTH NERVE 
OCULO-MOTOR 
NERVE 
TROCHLEAR, 
NERVE 
PITUITARY 
BODY 
SUPRAMAXILLARY 
NERVE / 
OPHTHALMIC 
NERVE 
SPHENOIDAL 
SINUS 
BODY OF 
SPHENOID 
FIBROUS TRABECUL/E 
Fig. 634.—Cavernous sinus, as shown by transverse section through the middle of the sella turcica. (W. 
Keiller.) 
which it is embedded (Fig. 634). Between layers of the dura it enters the 
sphenoidal fissure, having divided into a superior and inferior division. Thus it 
enters the orbit, passing between the two heads of the external rectus, the two 
divisions being separated by the nasal nerve. 
The superior division is directed inward and forward over the optic nerve, and 
SUPERIOR DI- 
VISION OF 
THIRD NERVE 
SUPRATROCH- 
LEAR NERVE 
INFERIOR DI- 
VISION OF 
THIRD NERVE 
INFRATROCH- 
LEAR NERVE 
OPHTHALMIC 
DIVISION 
NASAL 
THIRD 
NERVE 
OPTIC 
NERVE- 
FOURTH- 
NERVE 
FIFTH 
NERVE 
MANDIBULAR _ 
DIVISION OF 
FIFTH NERVE 
MAXILLARY 
NERVE ' 
MECKEL’S GANGLION 
POSTERIOR 
DENTAL NERVES 
Cl LIARY 
NERVES 
TEMPORO-MALAR 
NERVE 
INFRAORBI- 
TAL NERVE 
Fig. 635.—Oculomotor nerve and ciliary ganglion (C. G.). (Testut.) 
pierces the rectus superior to terminate in the levator palpebrse superioris, sup- 
plying these two muscles. 
The inferior division splits into three branches. Of these, one supplies the 
internal rectus, another the inferior rectus, and the third, larger than either of the THE THIRD OR OCULO-MOTOR NERVE. 
573 
others, passes between the inferior and external recti to enter the posterior border 
of the inferior oblique. This branch gives a short, thick offset to the ciliary 
ganglion, thus furnishing its motor root, and also contributes some twigs to the 
inferior rectus. 
The third nerve supplies all the orbital muscles, except the superior oblique 
(supplied by the fourth nerve) and external rectus (sixth nerve). It also, through 
the ciliary ganglion, supplies the ciliary muscle and sphincter iridis. It is further 
to be noted that the nucleus of this nerve, through communication with the roots 
of the facial, supplies the orbicularis palpebrarum, occipito-frontalis, and cor- 
rugator supercilii; and that the fibres of the third nerve to the internal rectus 
are derived from the sixth nucleus of the opposite side. It may be well to note 
here that all the orbital muscles are supplied by their nerves on their surfaces 
next the eyeball, except the inferior oblique which is pierced by its nerve on its 
OPTIC NERVE AND 
OPHTHALMIC ARTERY 
FOURTH NERVE 
FRONTAL NERVE 
LACHRYMAL NERVE 
-UPPER DIVISION OF 
THIRD NERVE 
-NASAL NERVE 
LOWER DIVISION OF 
THIRD NERVE 
-SIXTH NERVE 
TEMPOROMALAR 
NERVE 
Fig. 636—Back of the orbit, showing passage of nerves through sphenoidal fissure. (Modified from Testut.) 
OPHTHALMIC VEIN 
posterior border, and the superior oblique which is supplied by the fourth nerve 
on its orbital surface. 
Observe here, also, the relations of the orbital nerves in the cavernous sinus and 
sphenoidal fissure (Fig. 636). 
The third and fourth nerves and ophthalmic division of the fifth lie embedded 
in the outer wall of the cavernous sinus, while the sixth nerve and internal carotid 
artery pass through the sinus, the nerve lying beneath the artery, and both being 
separated from the blood of the sinus by an endothelial lining supported by 
delicate fibrous tissue. 
In the sphenoidal fissure the fourth, frontal, and lachrymal nerves are arranged 
along its upper boundary in the order mentioned from within outward; the supe- 
rior and inferior divisions of the oculo-motor, the nasal, and sixth nerves pass 
between the two heads of the external rectus, the nasal lying between the first two 
and the sixth most interiorly. The ophthalmic vein leaves the orbit through this 
fissure internallv to the sixth nerve. 574 
THE NERVES. 
The Fourth or Trochlear Nerve. 
The fourth nerve (called trochlear because its tendon runs through a pulley) 
arises in a short column of cells almost continuous with the third nucleus, and 
commensurate with the inferior quadrigeminal body. Thence the root runs 
dorso-laterally, and after descending for a short distance crosses inward in the 
valvula, where it decussates with its fellow, and emerges as a slender round 
bundle immediately behind the testis on the opposite side from its nucleus. The 
decussation of this nerve is altogether a peculiar feature. 
It now passes outward across the superior peduncle of the cerebellum, and 
forward round the outer side of the crus cerebri to pierce the dura under cover 
of the free margin of the tentorium, external to the posterior clinoid process and 
third nerve. It is embedded in the outer wall of the cavernous sinus between 
the oculo-motor and ophthalmic nerves, afterward crossing the oculo-motor to lie 
in the inner angle of the sphenoidal fissure through which it reaches the orbit. 
Here it runs inward above the levator palpebrse superioris and is distributed to 
the obliquus superior on its upper (orbital) surface. 
The Fifth or Trifacial Nerve. 
The fifth nerve is called trifacial because it has three grand divisions, which 
are distributed to the face ; and sometimes it is called trigeminal (“ three double ” 
or u three twins ”), referring to the arrangement of the divisions on the two sides 
of the head. It is mixed in function, closely resembling a spinal nerve in that 
the motor and sensory roots arise separately from the encephalon, the sensory 
root possessing a ganglion similar in constitution and development to that of a 
posterior spinal nerve-root, while the motor root joins the nerve on the distal side 
of the ganglion. 
The motor root arises from a group of cells lying deeply in the floor of the 
fourth ventricle at a point corresponding to the lateral recess. It is joined by the 
descending root which appears to arise from cells in the aqueduct and by a crossed 
motor root of doubtful connections. 
Most of the fibres of the sensory portion are traceable into the so-called 
ascending root which appears as a crescentic band of fibres outside the gelatinous 
substance of Rolando. The fibres appear to arise as axis-cylinder processes of 
the cells of the Gasserian ganglion and to terminate as minutely branching pro- 
cesses round the cells of the gelatinous substance and funiculi gracilis and cuneatus 
(compare sensory spinal nerve-root). Many sensory fibres end in the superior 
sensory nucleus, which lies just outside the motor nucleus. The crossed sensory 
and cerebellar roots are imperfectly understood. 
Thus, then, two roots can be seen coursing through the pons from whose ven- 
tral surface they emerge near its anterior border. The larger, sensory root (portio 
major) being ventro-lateral to the smaller, motor root (portio minor). 
The larger root runs forward beneath the tentorium, where, just under the 
fourth nerve and near the apex of the petrous portion of the temporal bone, it 
enters a recess between the two layers of the dura (Meckel’s space). Here the 
larger root spreads out, forming a plexiform network, and enters the Gasserian 
ganglion. 
The smaller root, from being dorsal to the portio major at its origin, winds 
spirally round the latter, gaining its inner and then its ventral (under) surface, 
and crosses beneath the Gasserian ganglion to join the third division only, which 
emerges from that structure. 
The Gasserian or Semilunar Ganglion.—This body lies on a special depression 
on the anterior surface of the petrous bone; it is crescent-shaped, the convexity 
being directed forward. Its surfaces are adherent to the dura, flattened, and much 
striated; and it is rich in ganglionic cells. It is joined by filaments from the 
carotid plexus of the sympathetic, and sends recurrent fibres to the dura. THE FIFTH OR TRIFACIAL NERVE. 
575 
From its convex border the sensory portion of the trifacial emerges in three 
trunks, the ophthalmic, superior maxillary, and inferior maxillary or mandibular, 
and the third of these alone is joined by the motor root after its emergence. 
LACHRYMAL N. 
SUPRATROCHLEAR N.- 
SUPRAORBITAL N. 
TEMPORAL BR. 
"OF TEMPORO-MALAR 
INFRATROCHLEAR N. 
NASAL NERVE- 
MALAR BR. OF 
"temporo-MALAR 
INFRAORBITAL- 
NERVE 
.AURICULOTEMPORAL 
NERVE 
BUCCAL NERVE- 
MENTAL NERVE- 
Fig. 637.—Sensory areas of the head, showing the general distribution of the three divisions of the trifacial 
nerve. (Modified from Testut.) 
A general idea of the cutaneous distribution of these nerves will be got from 
a glance at Fig. 637. 
INNER 
BRANCH 
PIERCES SUPRAOR- 
<BITAL FORAMEN 
BRANCH TO INFRA- 
TROCHLEAR 
PIERCES EXTERNAL TAR- 
SAL LIGAMENT TO SKIN 
OF EYELID 
SUPRATROCHLEAR 
TWIGS TO CONJUNCTIVA 
SUPRAORBITAL- 
TO LACHRYMAL GLAND 
INFRATROCHLEAR. 
Cl LI ARY - 
vTO ORBITAL BRANCH 
A OF ORBITOMALAR 
NASAL- 
NERVE 
.LACHRYMAL 
NERVE 
-FRONTAL 
NERVE 
-OPHTHALMIC DIVISION 
-SUPERIOR MAXILLARY 
DIVISION 
THIRD NERVE- 
-MANDIBULAR DIVISION 
SENSORY ROOT 
OF FIFTH NERVE 
-GASSERIAN GANGLION 
OF MOTOR ROOT 
Fig. 638.—Ophthalmic division of the trifacial nerve. (Testut.) 
First or Ophthalmic Division of the Fifth Nerve (Fig. 638).—The first or 
ophthalmic (“ eye ”) division of the fifth nerve is a flattened trunk, one inch long, 576 
THE NERVES. 
which runs forward and upward in the outer wall of the cavernous sinus under 
the fourth nerve. Between layers of dura it reaches the sphenoidal fissure, which 
it passes through in three divisions, the lachrymal, frontal, and nasal. It gives 
offsets to the third, fourth, and sixth nerves, as these enter the orbit. 
The Lachrymal Nerve is the outermost of these three divisions. It occupies 
a separate sheath of dura, and passes by the outer angle of the sphenoidal 
fissure into the orbit. Here it runs along the upper border of the external rectus to 
the outer and the upper angle of the cavity to reach the lachrymal (“ tear ”) gland. 
Just behind the gland it gives off a branch to join the orbital branch of the supe- 
rior maxillary nerve, and branches to the lachrymal gland and conjunctiva, and 
terminates by piercing the external tarsal ligament to supply the shin of the upper 
eyelid, where it communicates with the facial nerve. 
The Frontal Nerve, the middle and largest division of the ophthalmic, also 
enters the orbit close to the roof of the sphenoidal fissure. It runs forward on 
the levator palpebrse snperioris, between it and the periosteum. Midway in its 
passage through the orbit it gives off the supratrochlear nerve, and then, assuming 
the name supraorbital, runs straight to the supraorbital foramen. Through this 
foramen it leaves the orbit accompanied by the supraorbital branch of the oph- 
thalmic artery, and divides into an internal and an external branch, the external 
branch being the larger. These pierce the orbicularis palpebrarum and frontalis 
very obliquely, supplying the skin of the front part of the scalp, the external 
branch being traceable as far as the lambdoidal suture. 
The supratrochlear nerve, springing from the frontal, as above described, runs 
forward and inward toward the pulley of the superior oblique. Near the pulley 
it sends a twig to join the infratrochlear branch of the nasal; and then, passing 
over the superior oblique tendon, it lies between the orbicularis palpebrarum and 
the bone, as it passes over the inner angle of the orbital arch. Here it supplies 
twigs to the eyelid and conjunctiva, and then pierces the frontalis to reach the 
skin of the forehead over the glabella. It is accompanied by the frontal artery. 
These, like all other sensory branches of the fifth nerve, communicate with the 
facial. 
The Nasal Nerve enters the orbit between the two heads of the external 
rectus and two divisions of the oculo-motor nerve. At first on the outer side of 
the optic nerve, it crosses it obliquely beneath the rectus superior to reach the 
anterior internal orbital canal, through which, accompanied by the anterior eth- 
moidal vessels, it enters the cranium. In the orbit it gives off the sensory root to 
the ciliary ganglion, two long ciliary nerves, and the infratrochlear nerve. 
In the cranium it runs forward on the cribriform plate of the ethmoid and 
passes to the nasal fossa through the nasal slit. In the roof of the nose it gives off 
an internal or septal branch, and an external branch, and passes onward as the 
anterior or superficial branch in a groove on the nasal bone to become cutaneous 
by passing between that bone and the lateral cartilage of the nose. 
Branches.—(a) The branch to the ciliary ganglion is a slender filament, one- 
quarter inch long, which is given off when the nasal nerve lies between the heads 
of the external rectus. It furnishes the sensory root of the ganglion. 
(6) One or two long ciliary nerves pierce the sclerotic near the optic nerve. 
(c) The in fratrochlear nerve runs forward beneath the superior oblique, receives 
a communicating branch from the supratrochlear, and, passing beneath the pulley 
to the inner canthus, supplies the conjunctiva, caruncle, lachrymal sac, and skin 
of the eyelids and nose. 
(d) The internal or septal branch supplies the mucous membrane on the upper 
and anterior part of the nasal septum. 
(e) The external branch supplies the outer wall of the nose, including the 
anterior ends of the middle and inferior turbinated bones. 
(/) The anterior or superficial branch pierces the compressor naris and is dis- 
tributed to the skin of the lower part of the nose. 
Sporadic Ganglia connected with the Fifth Nerve.—There are four small gan- THE FIFTH OR TRIFACIAL NERVE. 
577 
glia connected with the fifth nerve—the ophthalmic, sphenopalatine, otic, and sub- 
maxillary. Each of these has three roots, derived from motor, sensory, and 
sympathetic nerves respectively, and a varying number of branches of distribu- 
tion. Their cells are multipolar, thus resembling the cells of sympathetic ganglia, 
and differing from those of the ganglia of the posterior spinal nerve-roots and 
Gasserian ganglion. 
The Ophthalmic, Ciliary, or Lenticular Ganglion (Fig. 635).—The ciliary gan- 
glion is a small reddish body about the size of a large pin-head (one-twelfth of an 
inch in long diameter), compressed laterally, and quadrilateral in shape, present- 
ing four angles. It lies at the back of the orbit, between the external rectus and 
the optic nerve, and is often in contact with the ophthalmic artery. 
Its long (sensory) root is derived from the nasal nerve, entering its supero- 
posterior angle. Often incorporated with this or entering the ganglion by its 
side is the sympathetic root, derived from the cavernous plexus; and its motor 
root is a short, comparatively thick offset from the branch of the third nerve to 
the inferior oblique, which enters the postero-inferior angle of the ganglion. 
SPHENO-PALATINE 
BRANCHES V 
INFERIOR 
"PALPEBRAL 
VIDIAN 
MECKEL'S GANGLION 
PALATINE BRANCHES 
LATERAL 
I* NASAL 
POSTERIOR DENTAL 
INFRAORBITAL BRANCHES 
OF FACIAL 
NFRAORBITAL 
SUPERIOR LABIAL 
Fig. 639.—Maxillary division of the trifacial nerve and Meckel’s ganglion. (Testut.) 
From the anterior angles of the ganglion spring its brandies of distribution 
called the short ciliary nerves. There are at first six to eight of them, arranged 
in two groups, superior and inferior, the inferior group being joined by the long 
ciliary nerves from the nasal. They pass along the upper and lower surfaces of 
the optic nerve, subdividing until about twelve to eighteen fine filaments reach 
the sclerotic, and pierce it in a circle round the optic nerve. They supply nerves 
of ordinary sensation and trophic nerves to the eyeball (derived from the nasal), 
motor nerves to the ciliary muscle and sphincter iridis (derived from the oculo- 
motor), and sympathetic nerves to the dilatator fibres of the iris. 
The Second or Maxillary Division of the Fifth Nerve (Fig. 639).—The maxillary 
(superior maxillary) nerve is intermediate* in size and position between the two 
other divisions of the fifth nerve, and like the first is purely sensory. After a 578 
THE NER VES. 
very short intracranial course it passes through the foramen rotundum, crosses 
the sphenomaxillary fossa, and enters the orbit through the sphenomaxillary 
fissure to occupy the infraorbital groove in its floor. It is here joined by the 
infraorbital branch of the internal maxillary artery, and together they enter the 
infraorbital canal to reach the face beneath the orbit, where the nerve divides into 
its terminal branches. 
Branches.—(a) Recurrent branch. Within the cranium it gives a recurrent 
branch to the dura and middle meningeal artery. 
(6) The orbital branch (tempero-rnalar nerve) is given off in the sphenomaxil- 
lary fossa. It enters the orbit through the sphenomaxillary fissure, and divides 
into two branches, temporal and malar. 
The temporal branch runs upward along the outer wall of the orbit, gives a 
communicating filament to the lachrymal nerve, and passing obliquely through 
the periosteum enters the sphenomalar canal. It thus passes to the temporal 
fossa, where, running upward between the temporal muscle and the bone, it 
pierces the deep and superficial layers of the temporal fascia very obliquely, and 
emerges subcutaneously one inch above the zygoma, where its twigs perforate the 
orbicularis palpebrarum to the skin, communicating with the facial and auriculo- 
temporal nerves. 
The mnlar branch (ramus subcutaneus make) runs forward in the fat of the 
orbit, and pierces through the malar canal to the skin of the face over the malar 
bone. 
(c) The sphenopalatine branches are two short, stout twigs to Meckel’s gan- 
glion, with which they will be described. 
POSTERIOR 
SUPERIOR 
MAXILLARY 
ORBITAL 
BRANCH—CUT 
MECKEL’S 
GANGLION 
OCULO- 
MOTOR 
GREAT SUPER- 
FICIAL PETROSAL 
"ACIAL 
MIDDLE 
DENTAL 
ANTERIOR 
DENTAL 
JACOBSON'S 
4) GREAT I 
1/ DEEP fl 
PETROSAL] 
VIDIAN 
I QLOSSOPHA- 
I RYNGEAL 
DENTAL 
PLEXUS 
SUPERIOR CERVICAL 
GANGLION OF THE 
Fig. 640.—-Dental branches of superior maxillary nerve and sphenopalatine ganglion. (Testut.) 
SYMPATHETIC 
(d) The posterior superior dental nerves (Fig. 640), the last branches given off 
in the sphenomaxillary fossa, are usually two in number, or may arise together. 
Running downward on the back of the superior maxilla, in the grooves which 
lead to the posterior dental canals, they give fibres to the gums and buccal 
mucous membrane (nervuli gingivales) and then enter these canals to supply the 
molar teeth and antrum. 
(e) The middle superior dental nerve is given off in the hind part of the infra- 
orbital canal. It descends in a minute canal or groove in the outer wall of the 
antrum to supply the bicuspid teeth. 
(f) The anterior superior dental nerve commences in the fore part of the infra- 
orbital canal. It also descends in the wall of the antrum, dividing into two THE FIFTH OR TRIFACIAL NERVE. 
579 
branches : a nasal branch which supplies the mucous membrane of the anterior 
part of the inferior meatus and floor of the nasal fossa ; and a dental branch to the 
incisor and canine teeth. 
These three dental nerves form loops (the superior dental plexus) in the 
minute canals provided for them in the maxilla, and from the loops filaments pass 
to the foramina at the tips of the fangs, and supply the dental pulp. 
(g) Infraorbital Nerve.—From the time the maxillary nerve enters the infra- 
orbital canal it is called the infraorbital nerve, and under that name it emerges on 
the face, where it lies deeply under cover of the levator labii superioris proprius. 
Here it divides into seven or more branches. Two of these, called inferior pal- 
pebral, turn upward to the skin and conjunctiva of the lower eyelids ; two or 
three pass inward between the fibres of the levator labii superioris alseque nasi to 
the side of the nose (lateral nasal); and three or four superior labial branches run 
downward, piercing the fibres of the elevators of the upper lip and angle of the 
mouth to the skin of the lips and cheek, and sending large twigs to the mucous 
membrane. 
These infraorbital nerves communicating with the facial form the infra- 
orbital plexus. 
The Sphenopalatine or Meckel’s Ganglion (Figs. 640, 641).—The sphenopala- 
SENSORY ROOTS 
JNTERNAL BRANCHES THROUGH 
SPHENO-PALATINE FORAMEN. 
SUPER FOR MA)CI LLARY N. 
NASAL BRANCH OF VIDIAN 
ASCENDING OR ORBITAL 
< BRANCHES THROUGH 
PHENO-MAXI LLARY 
FISSURE 
MOTOR ROOT 
(great petrosal of facial) 
SYMPATHETIC ROOT 
(from carotid plexus) 
PHARYNGEAL BRANCH^ 
POSTERIOR PALATINE 
ANTERIOR PALATINE 
MIDDLE PALATINE 
DESCENDING 
BRANCHES 
Fig. 641.—Diagram of constitution of sphenopalatine ganglion. (W. Keiller.) 
tine, or Mechel’s ganglion, is a small, reddish, triangular body, one-fifth of an inch 
in its long diameter, and flattened at the sides. It is situated in the upper part 
of the sphenomaxillary fossa, just under the superior maxillary nerve, where it is 
embedded in fat and surrounded by the terminal branches of the internal max- 
illary artery. Only its posterior segment contains nerve-cells. 
Its sensory root is represented by two short, stout nerves, which attach its two 
superior angles to the superior maxillary nerve, forming its sphenopalatine branches. 
The greater part of these roots passes on without interruption in ganglion-cells 
into the palatine, nasal, and pharyngeal branches of the ganglion. 
Its motor and. sympathetic roots are contained in the Vidian nerve. 
The Vidian Nerve is a compound nerve, formed by the junction of the great 
superficial and great deep petrosal nerves. Tracing the Vidian nerve backward to 
its sources, it leaves the postero-superior angle of the ganglion, passes through the 
Vidian canal (accompanied by the artery of the same name) in which it gives otf 
small twigs to the back of the nose and pharynx, and divides into two branches. 580 
THE NERVES. 
Of these the great superficial petrosal nerve enters the cranium through the carti- 
lage which closes the foramen lacerum medium by the outer side of the internal 
carotid artery, and, passing backward and outward in a groove on the petrous 
bone under the Gasserian ganglion, enters the hiatus Fallopii to join the genicu- 
late ganglion of the facial nerve. It receives a twig from the tympanic branch of 
the glossopharyngeal. The great deep petrosal nerve, which joins this to form the 
Vidian nerve just outside the Vidian canal, can be traced to the plexus of the 
sympathetic on the internal carotid artery. Some works describe this as the 
carotid branch of the Vidian, and give the name of great deep petrosal to the 
twig from the glossopharyngeal which joins the great superficial petrosal. The 
branches of distribution of Meckel’s ganglion are grouped as ascending, internal, 
descending, and posterior. 
(а) Ascending Branches.—These are the orbital branches, two or three exceed- 
ingly minute twigs which pass through the sphenomaxillary fissure to the perios- 
teum of the orbit, and the mucous membrane of the posterior ethmoidal and 
sphenoidal sinuses. 
(б) Internal branches are partly derived from the ganglion ; but are largely 
traceable over its inner surface into the sensory roots. They are superior nasal 
and nasopalatine. 
The superior nasal nerves are several small twigs which enter the nose through 
the sphenopalatine foramen, to supply the mucous membrane over the upper and 
back part of the superior and middle turbinated bones and septum, as well as the 
posterior ethmoidal cells. 
The nasopalatine nerve (Fig. 628) passes to the nasal septum, also through the 
sphenopalatine foramen. It runs downward and forward in a groove on the vomer 
between the periosteum and mucous membrane, contributing some small septal 
branches and communicating with the nasal branch of the anterior superior dental 
nerve. The two nasopalatine nerves, one on each side of the nasal septum, thus 
reach the median segments of the anterior palatine canal (foramina of Scarpa), 
through which they pass to the roof of the mouth, the left nerve occupying the 
anterior foramen. 
In the lower part of the anterior palatine canal they unite in a plexiform net- 
work, and are then distributed to the mucous membrane behind the incisor teeth, 
communicating with the anterior palatine nerve. 
(c) Descending Branches (Fig. 629).—These are the three palatine nerves, ante- 
rior or great, posterior or small, and external. They are frequently given off as 
one trunk. 
The great or anterior palatine nerve, springing from the lower angle of Meckel’s 
ganglion, descends in the posterior palatine canal, and runs forward, in grooves, on 
the hard palate, supplying the gums and roof of the mouth, and communicating 
with the nasopalatine nerve. It contributes inferior nasal branches to the back 
part of the inferior turbinated bone and middle and inferior meatus. 
The small or posterior palatine nerve descends in one of the accessory palatine 
canals to the tonsil, uvula, and soft palate, and through it motor fibres possibly 
pass from the facial nerve to the levator palati and azygos uvulae, though the pars 
accessoria ad vagum is now regarded as supplying these muscles. 
The external palatine nerve occupies another accessory palatine canal, in which 
it descends to the soft palate and tonsil. It is occasionally absent. 
(d) Posterior Branches.—The twigs supplied by the Vidian in the Vidian 
canal to the upper part of the nose are derived from the sphenopalatine roots of 
the ganglion, and only accompany the Vidian nerve. 
The pharyngeal branch springs from the ganglion beside the Vidian, with 
which it may be incorporated. It runs backward in the pterygopalatine canal 
with the vessel of that name to the posterior nares and nasopharynx, Eustachian 
tube, and sphenoidal sinuses. 
The Third, Inferior Maxillary, or Mandibular Division of the Fifth Nerve (Fig. 
642).—The mandibular division of the fifth nerve is larger than either of the THE FIFTH OB TRIFACIAL NERVE. 
581 
others, and is formed by the third segment of the sensory root with the entire 
motor root, the two leaving the cranium through the foramen ovale, and uniting 
almost immediately afterward to form a single mixed nerve-trunk. About one- 
fourth of an inch below the base of the skull this short trunk divides under 
cover of the external pterygoid muscle into a smaller or anterior, and a larger or 
posterior, division. 
Before it divides, the trunk gives off a recurrent nerve, and the nerve to the 
internal pterygoid. 
The recurrent branch enters the cranium through the foramen spinosum, and 
sends a twig to the lining membrane of the mastoid cells, and another to the sub- 
stance of the petrous bone. 
The nerve to the internal pterygoid passes under the posterior border of that 
muscle supplying it on its deep surface. Near the origin of the nerve and lying 
on it is the otic ganglion, to which it contributes its sensory root. 
ANTERIOR " 
AURICULAR 
POSTERIOR TEMPORAL 
.MALAR 
TEMPORAL BRANCH 
BRANCHES TO 
MEATUS 
-INFRAORBITAL 
OF BUCCAL 
COMMUNICATING 
TO FACIAL 
PAROTID . 
BRANCHES 
-ARTICULAR 
-LONG BUCCAL 
AURIC'J LO- 
TEMPORAL 
INFERIOR 
DENTAL 
M ENTAL 
MYLOHYOID 
LINGUAL 
Fig. 642.—Mandibular division of the trifacial nerve. (Testut.) 
The smaller or anterior division of the mandibular trunk is mainly motor in 
function. Its branches are as follow ; 
(a) The deep temporal nerves, anterior and posterior. Of these the posterior 
frequently springs from one common trunk with the masseteric nerve. They run 
upward over the upper border of the external pterygoid muscle and between the 
temporal muscle and the bone, supplying the latter muscle on its deep surface. 
(p) The masseteric nerve, frequently starting in common with the posterior 
deep temporal nerve, passes over the upper border of the external pterygoid, 
and through the sigmoid notch of the mandible behind the insertion of the tem- 
poral muscle, accompanied by the masseteric vessels. It enters the deep surface 
of the masseter muscle. It supplies a filament to the temporomaxillary articula- 
tion. 582 
THE NERVES. 
(c) The external pterygoid nerve is given off from the long buccal nerve, which 
also contributes some fibres to the temporal muscle. 
(d) The long buccal nerve, with the exception of those branches just mentioned, 
is purely sensory. It passes between the two heads of the external pterygoid 
muscle, and runs downward and forward under cover of the temporal muscle and 
anterior border of the masseter to the buccinator. Between the masseter and 
buccinator it divides into branches to the skin and mucous membrane of the 
cheek, the latter piercing the fibres of the buccinator. It communicates with the 
facial, forming a plexus around the facial vein called the buccal plexus. 
The larger or posterior division is almost entirely derived from the sensory 
root, the only motor fibres it contains passing along the inferior dental nerve to 
form its mylohyoid branch. Its branches are as follow : 
(а) The auriculotemporal nerve arises by two roots which usually enclose the 
middle meningeal artery. It passes backward and outward close under the tem- 
poromaxillary articulation, then upward between it and the external auditory 
meatus, under cover of the upper part of the parotid gland. Emerging from 
under the gland it crosses the root of the zygoma with the superficial temporal 
artery slightly behind which it lies, and divides into superficial temporal branches 
to the skin of the temple. 
In this course it gives off (1) articular twigs, one or two fine filaments to the 
temporomaxillary articulation. 
(2) Communicating branches, consisting of one or two stout branches to the 
facial nerve ; and slender filaments to the otic ganglion, which latter are im- 
portant because they conduct secretory fibres from the glossopharyngeal nerve 
to the parotid gland, by way of the lesser petrosal nerve, otic ganglion, and 
parotid branches of the auriculotemporal. 
(3) Two nerves to the meatus pass between the bony and cartilaginous part of 
the external auditory meatus, and supply the skin of the meatus, contributing a 
twig to the tympanic membrane. 
(4) Several parotid branches pass from the nerve itself, or its communicating 
branches to the facial nerve, into the gland substance. 
(5) Two anterior auricular branches supply the skin over the tragus and 
npper part of the pinna. 
(б) The superficial temporal nerve is the termination of the auriculotemporal. 
The posterior division breaks up into branches which cross the posterior branch 
of the temporal artery, the anterior division communicates with the temporal 
branches of the facial nerve. They supply the skin of the temporal region. 
(6) The Inferior Dental Nerve (Fig. 643) is the largest branch of the mandib- 
ular division of the fifth nerve. It emerges from under the lower border of the 
external pterygoid muscle, and running downward upon the internal lateral liga- 
ment of the lower jaw, with the inferior dental artery behind and the lingual 
nerve in front of it, it enters the inferior dental canal. Before entering the 
canal it gives off the mylohyoid nerve. 
In the inferior dental canal it runs forward toward the symphysis menti, sup- 
plying branches to the teeth and gums, and opposite the mental foramen it divides 
into a mental and an incisive branch. The incisive branch runs forward in the con- 
tinuation of the dental canal to supply the canine and incisor teeth and cor- 
responding part of the gums; while the mental branch appears on the face by 
issuing through the mental foramen with a companion artery, and, under cover 
of the depressor anguli oris, divides into a descending branch to the integument 
of the chin, and two ascending branches to the skin and mucous membrane of 
the lower lip. It communicates with the supramandibular division of the facial 
nerve. 
The mylohyoid branch of the inferior dental nerve is rather to be regarded as 
coming straight from the motor root and only accompanying the inferior dental 
in its sheath as far as the inferior dental canal. It occupies the mylohyoid groove 
with an artery of the same name, and runs in the recess under the mylohyoid THE FIFTH OB TRIFACIAL NERVE. 
583 
muscle and between it and the mandible, supplying that muscle and the anterior 
belly of the digastric. 
(c) The Lingual (wrongly called the gustatory) Nerve (Figs. 643, 644) lies at 
first under cover of the external pterygoid muscle, in front of and a little deeper 
than the inferior dental nerve, to which it is connected by a short branch. Here, 
also, it is joined at an acute angle by the chorda tympani nerve from the facial. 
It runs downward and forward on the internal pterygoid muscle and mandibular 
attachment of the superior constrictor of the pharynx, and reaches the inner side 
of the lower jaw, close under the last molar tooth, where it lies immediately 
under the mucous membrane, and may be readily reached by the surgeon, or 
injured in careless dentistry. It then lies between the hyoglossus and mylohyoid 
muscles above the deep portion of the submaxi 11 ary gland, and crosses Wharton’s 
duct obliquely as it bends upward toward the tip of the tongue. 
SMALL PETROSAL/ 
OTIC GANGLION ' 
BRANCH TO TEN 
SOR TYMPAN 
.BRANCH TO AURiC 
ULO-TEMPORAL 
IRANCH TO TEN- 
BRANCH TO TEN 
SOR PALATI 
NERVE TO IN 
'CHORDA TYMPANI 
■ MIDDLE MENINGEAL 
ART. WITH SYMPA- 
SOR PALAT 
TERNAL PTERY- 
GOID 
THETIC PLEXUS 
'•'AURICU LO “TEM- 
PORAL 
SMALL PETROSAL 
BRANCH TO TEN- 
SOR TYMPANI 
OTIC GANGLION 
BRANCH FROM 
GANGLION TO 
SUBLINGUAL 
GLAND 
NERVE TO ) 
INTERNAL f 
pterygoid) 
CHORDA 
TYMPANI 
BRANCH TO CHOR- 
DA TYMPANI 
TO DI- 
GASTRIC 
TO MYLO- 
. HYOID j 
SYMPATHETIC 
ROOT OF 
GANGLION 
LOOP BETWEEN 
LINGUAL AND 
HYPOGLOSSAL 
SUBMAXILLARY 
GANGLION 
NERVE TO 
TENSOR PAL AT I 
Fig. 643.—Mandibular division of trifacial nerve, seen from the middle line. The small figure is an 
enlarged view of the otic ganglion. (Testut.) 
Its communicating branches are those above mentioned—namely, to the inferior 
dental, and by the chorda tympani to the facial nerve, in addition to which there 
are the motor and sensory roots to the submaxillary ganglion, and one or two fila- 
ments which, under the mylohyoid muscle, join it with the hypoglossal nerve. 
It distributes twigs to the mucous membrane of the floor of the mouth between 
the tongue and the gums, a branch to the sublingual gland (from the chorda 
tympani nerve), and ends by breaking up into fibres for the anterior two-thirds 
of the tongue, supplying chiefly the fungiform and filiform papillae. 
The Submandibular (Submaxillary) Ganglion (Fig. 643).—In a small triangular 
space under cover of the mylohyoid muscle, having the lingual nerve above, Whar- 
ton’s duct below, and the submaxillary gland behind, lies a reddish body about the 
size of a pin-head, the submandibular (.submaxillary) ganglion. Its roots are repre- 
sented by one branch (or several) running downward and forward to it from the 584 
THE NERVES. 
lingual, conveying to it chorda-tympani and trifacial fibres (motor and sensory), 
and filaments which join it from the sympathetic plexus round the facial artery. 
It distributes branches to the submaxillary gland and Wharton’s duct, and a 
branch to the sublingual gland, which reaches the gland by joining the lingual, 
assuming the appearance of another root. 
The Otic Ganglion (Fig. 643).—The otic (“earganglion is a small reddish 
gray, oval body, compressed from side to side, and about one-sixth of an inch 
in its long diameter. It is closely attached to or may surround the nerve to 
the internal pterygoid muscle, lying on the inner side of the mandibular trunk 
GASSERIAN GANGLION 
SPINAL ACCESSORY- 
INTERNAL JUGULAR 
VEIN 
SECOND CERVICAL- 
THIRD CERVICAL- 
PcOMMUN I GATING 
\ TO LINGUAL 
FOURTH CERVICAL- 
'THYROHYOID ERANCH 
LARYNGEAL 
FIFTH CERVICAL- 
SIXTH CERVICAL- 
Fig. 644.—Nerves of the tongue. (Testut.) 
close to the foramen ovale. Behind it is the middle meningeal artery, and on its 
inner side are the Eustachian tube and tensor palati muscle. 
Its motor and sensory roots reach it through the nerve to the internal ptery- 
goid muscle; but it is also connected with the facial and glossopharyngeal nerve 
through the small superficial petrosal nerve. From the plexus round the middle 
meningeal artery it receives its sympathetic root. 
It distributes branches to join the auriculotemporal, by which route the parotid 
gland is supplied from the glossopharyngeal nerve; also muscular twigs to the 
tensor palati and tensor tympani, and a communicating filament to the chorda THE SEVENTH OB FACIAL NERVE. 
585 
tympani nerve. Of the muscular fibres most may be traced to the trunk of the 
mandibular division of the fifth nerve, without interruption in the ganglion-cells. 
The Sixth or Abducent Nerve. 
The sixth nerve (Fig. 636) is purely motor, supplying the external rectus 
muscle of the eyeball. Its nucleus consists of a compact group of cells in the 
floor of the fourth ventricle, which forms the prominence known as the eminentia 
teres. It is in series with the third, fourth, and twelfth nuclei, and is surrounded 
by the seventh or facial roots, but has no connection with them. Its most im- 
portant connection is with the opposite oculomotor root by fibres which cross 
over and ascend in the posterior longitudinal bundle ; and thus the nucleus of 
the sixth nerve supplies the external rectus of its own side directly, and the 
internal rectus of the opposite side indirectly, through the opposite third nerve. 
The nerve roots run ventrolaterally through the pons to emerge as a flattened 
band from the groove between the oblongata and pons, just external to the ante- 
rior pyramid. This soon becomes rounded and pierces the dura at the side of 
the dorsum selhe, behind and internal to the fifth nerve. It passes through the 
cavernous sinus, lying under the carotid artery, and gains the orbit through the sphe- 
noidal fissure, where it lies between the two heads of the external rectus, beneath 
the inferior division of the third nerve, and above the ophthalmic vein. It then 
runs forward on the inner surface of the external rectus muscle, which it supplies. 
In the cavernous sinus the sixth nerve receives filaments from the carotid plexus 
of the sympathetic and, as it enters the orbit, it communicates with the ophthalmic 
division of the fifth. 
The Seventh or Facial Nerve. 
The seventh nerve (Fig. 645), excepting what will be described as the pars 
intermedia, is purely motor to the face muscles. Its nucleus lies deeply embedded 
in the pons on a level with the striae acusticae. It is in line with the motor 
nuclei of the fifth and ninth. The root of this nerve pursues a very circuitous 
course through the pons, running first dorsally, then upward, next laterally 
above, and finally ventrally on the outside of the sixth nucleus. It emerges from 
the groove between the pons and oblongata, external to the olivary body and in 
the same transverse plane as the eighth nerve. Between its superficial origin and 
that of the eighth nerve, springs a small bundle called by Wrisberg the pars 
intermedia. The seventh, eighth, and pars intermedia run together outward into 
the internal auditory meatus, the seventh nerve lying in a groove on the upper 
and fore part of the auditory nerve, the pars intermedia being between them. 
The pars intermedia, in spite of some apparent connections with the eighth 
nerve, has no real continuity with it. It arises from the upper part of the glosso- 
pharyngeal nucleus, joins the facial nerve immediately after the latter enters the 
aqueductus Fallopii, and is probably the main constituent of the chorda tym- 
pani nerve. 
At the bottom of the internal auditory meatus the facial nerve enters the 
aqueductus Fallopii. In this canal it runs first outward between the cochlea and 
vestibule till it abuts on the inner wall of the tympanum ; backward in the sub- 
stance of the inner tympanic wall, above the fenestra ovalis, being here separated 
from the tympanum by a thin lamina of bone and the lining membrane of the 
middle ear ; and lastly it turns somewhat acutely downward behind the pyramid 
and posterior tympanic wall to appear at the base of the skull through the stylo- 
mastoid foramen. 
At the point where it bends sharply backward the bend is capped by a some- 
what conical swelling called the geniculate ganglion. 
On issuing from the petrous bone the facial nerve runs downward and for- 
ward through the substance of the parotid gland, superficial to the external 586 
THE NEli VES. 
R INFRA- 
SSTtrochlear 
BITAL 
ilp'-BUCCAL 
anddrGawlng“bryawalKefl7er:)CUtaneoUS branches °f fifth nerve’ and suPerficial cervical nerves. (Dissection THE SEVENTH OR FACIAL NERVE. 
587 
carotid artery, and behind the ramus of the lower jaw divides into a superior or 
tetriporofacial and an inferior or cervicofacial division, which break up into the 
numerous branches distributed to the face and submandibular region. 
The branches of the facial nerve may be divided into three groups : (A) those 
given off in its course through the petrous bone, (JB) those arising from the trunk 
at the base of the skull, and (C) those springing from its two great terminal 
divisions. 
[A) Branches of the Facial Nerve in its Course through the 
Petrous Bone.—(a) Filaments connect the geniculate ganglion with the ves- 
tibular division of the auditory. 
(b) The great superficial petrosal nerve is the largest of the three branches 
given off from the geniculate ganglion. It has been described with Meckel’s 
ganglion, of which it forms the motor root. 
(c) The small superficial petrosal nerve is also given off from the geniculate 
ganglion. It traverses a canal just external to the hiatus Fallopii, where it is 
joined by a branch from the tympanic plexus of the glossopharyngeal. It goes 
to the otic ganglion, leaving the cranium in the interval between the great wing 
of the sphenoid and petrous bone, or through a small canal beside the foramen 
ovale. 
(d) The external superficial petrosal nerve, the last of the three branches from 
the geniculate ganglion, traverses a small canal in the petrous bone, and passes to 
the sympathetic plexus on the middle meningeal artery. It is not constant, 
(e) A branch to the stapedius muscle is given off from the facial nerve as it 
descends behind the pyramid. 
(/) The chorda tympani nerve, given off from the facial at the lower end 
of the aqueductus Fallopii and containing nearly the whole pars intermedia, 
enters the back part of the tympanum, crosses that cavity on the inner side of 
the handle of the malleus under a covering of the lining membrane, and gains the 
base of the cranium by a canal at the inner side of the Glaserian fissure. It runs 
downward and forward under cover of the external pterygoid muscle, and joins 
the lingual nerve, after receiving twigs from the otic ganglion. It is conducted 
by the lingual nerve to the submaxillary ganglion, and to the anterior two-thirds 
of the tongue, forming the path for the sense of taste between that section of the 
organ and the glossopharyngeal nucleus. 
(g) Just before leaving the aqueductus Fallopii the facial nerve gives a twig 
to the auricular branch of the pneumogastric, as it courses through the temporal 
bone. 
(B) Branches given off between the Base of the Skull and its 
Final Division.—[a) The posterior auricular nerve commences just after the facial 
nerve has appeared at the base of the skull. It passes backward in the deep 
recess between the mastoid process and the external ear, communicating with 
the auricular branch of the pneumogastric, and sends a vertical branch upward to 
the retrahens aurem, attollens aurem, and small muscles on the cranial surface 
of the auricle, and a horizontal branch backward over the temporal bone to the 
occipitalis. 
It communicates with the great auricular and small occipital nerves. 
(b) Just below the preceding nerve arises the nerve to the 'posterior belly of the 
digastric. One of its branches frequently joins the glossopharyngeal nerve. 
(c) The nerve to the stylohyoid muscle may be given off along with the last in 
one common trunk or separately at the same level. 
(d) A lingual branch is described. It passes on the outer side of the stylo- 
pharyngeus muscle to the side of the pharynx, where it is joined by twigs from 
the glossopharyngeal. It then passes between the palatoglossus and the tonsil, and 
at the base of the tongue divides into filaments to the mucous membrane and 
palatoglossus and styloglossus muscles. 
(C) The two great Terminal Divisions of the facial are distributed in a 
manner which may be summarized as follows : 588 
THE NER VES. 
Running forward in the substance of the parotid gland, in which they cross 
superficially to the external carotid artery and temporo-maxillary vein, the tern- 
porofacial division after receiving a stout branch from the auricnlo-temporal 
nerve, subdivides into temporal, malar, and infraorbital branches, and the cervico- 
facial division into buccal, supramandibular, and inframaxillary branches ; the 
parotid duct separating the infraorbital from the buccal nerve. Leaving out the 
inframandibular nerve, these branches spread all over the face, each occupying 
mainly the region which its name indicates. They form, by interlacing with each 
other and with the various cutaneous branches of the fifth nerve, an intricate net- 
work called the pes anserinus (“goose’s foot”), and supply all the face-muscles, 
including the buccinator, the frontalis, and the anterior muscles of the auricle. 
The inframandibular branch emerges from the parotid gland behind the angle 
of the lower jaw, runs downward and forward under the platysma over the 
inframandibular and adjacent region of the neck, communicating freely with the 
great auricular and superficial cervical nerves, and supplying the platysma on its 
under surface. 
It should further be said that the zygomatic muscles and levator labii supe- 
rioris lie superficial to the infraorbital branch, and the risorius, depressor anguli 
oris, and depressor labii infcrioris cross the supramandibular branch ; but with 
these exceptions the branches of the facial nerve are superficial. 
Branches from the Temporofaciae Division.—The temporal branch of 
the temporofacial division of the facial nerve passes upward through the parotid 
gland, over the zygoma, and divides into branches, which supply the orbicularis 
palpebrarum, frontalis, corrngator snpercilii, attrahens and attollens aurem, and 
small muscles of the front of the pinna. Its branches form numerous communica- 
tions with each other, with the malar branch, and with the auriculotemporal, tem- 
poral, lachrymal, and supraorbital branches of the fifth nerve. 
Note.—The branches to the frontalis and orbicularis palpebrarum are derived 
from the nucleus of the third nerve. 
The malar branch runs forward over the malar bone, and is distributed mainly 
to the orbicularis palpebrarum. It sends filaments to both eyelids and communi- 
cates freely with the temporal and infraorbital branches of the facial, and the 
supraorbital, lachrymal, malar, and infraorbital branches of the fifth nerve. 
The infraorbital branch emerges from the anterior border of the parotid gland 
just above the parotid duct, and divides into branches which radiate to the region 
of the face between the orbit and the mouth. They pass under the zygomatic 
muscles and the levator labii superioris, under the latter muscle forming with the 
infraorbital branch of the fifth nerve the infraorbital plexus. It communicates 
also with the neighboring facial branches (malar and buccal) and with the buccal, 
malar, nasal, and infratrochlear branches of the fifth ; and supplies the zygomatic 
muscles, levator anguli oris, levator labii superioris, levator labii superioris alseque 
nasi, pyraraidalis nasi, compressor nasi, and depressor alse nasi; also the buc- 
cinator and orbicularis oris. 
Branches from the Cervicofacial Division.—The cervicofacial division 
runs downward and forward in the parotid gland crossing the external carotid 
artery. In the substance of the gland it receives fibres from the great auricular 
nerve. It divides into the following three branches : 
The buccal branch emerges from the parotid gland under the parotid duct, 
crosses the masseter muscle, and breaks up into twigs to the buccinator and 
orbicularis oris. It communicates with neighboring branches of the facial and 
with the long buccal nerve. 
The supramandibular branch crosses the masseter muscle and facial vessels on 
the body of the mandible, and under the risorius and depressors of the lower lip 
passes toward the chin. It supplies the risorius, depressor anguli oris, depressor 
labii inferiors, and levator menti, and communicates with the buccal and infra- 
mandibular branch of the facial and with the mental branch of the inferior dental 
nerve. THE EIGHTH OB A EDITOR Y NEB VE. 
589 
The inframandibular branch has already been sufficiently described. 
{Note.—The fact that the frontalis, orbicularis palpebrarum, and corrugator 
supercilii, escape in cortical facial paralysis, furnishes clinical evidence of a con- 
nection between the facial nerve and the oculo-motor nucleus, which probably 
takes place through the posterior longitudinal bundle. The association of the 
movements of the lips and tongue, and the involvement of the orbicularis oris in 
bulbar paralysis suggest that this muscle is supplied from the hypoglossal (twelfth) 
nucleus. This is probably effected by a communication from the nucleus of the 
twelfth to the facial nerve through the posterior longitudinal fasciculus.) 
The Eighth or Auditory Nerve. 
Nucleus of the Eighth or Auditory Nerve (Fig. 646).—The auditory nerve 
springs from the lower border of the pons, just external to the facial, by two 
bundles. The more lateral or posterior of these is mainly distributed to the 
STAPES 
AUDITORY NERVE 
Fig. 646.—Distribution of the auditory nerve. (Semidiagrammatic.) (Testut.) 
cochlea, and is regarded as the true nerve of hearing; the mesial or anterior 
bundle supplies the semicircular canals (except the posterior) and its function is 
to convey the sense of equilibrium. As these roots plunge into the pons, they 
separate so as to pass one on each side of the restiform body. 
The lateral or cochlear root is divisible into several parts. The outer fibres 
pass dorsally along the outer side of the restiform body, and enclose a large 
number of cells, similar to those of a spinal ganglion, which form the ganglion of 
the cochlear root. Thence fibres pass dorsally to end in the dorsal nucleus and 
striae medullares. The more mesial fibres of the cochlear root come into relation 
with a triangular group of cells, which lies ventral to the restiform body and forms 
the accessory or ventral auditory nucleus. Other fibres pass by the trapezium to 
the superior olive of the same and opposite sides. It is also connected with the 
flocculus. The mesial or vestibular root passes to the inner side of the restiform 
body, between it and the ascending root of the fifth nerve. When it reaches the 
dorsomesial side of the restiform body, most of its fibres bend caudally, and run 590 
THE NERVES. 
along the inner side of the restiform body and cimeate nucleus forming the 
ascending root. The fibres of this ascending root probably end in arborizations 
round the cells of the cuneate nucleus. The rest of the fibres of the vestibular 
root pass dorsally to end in the internal auditory or dorsal nucleus, which is a 
large group of cells corresponding in position to the tuberculum acusticum, and 
lying close to the floor of the ventricle dorsomesially to the restiform body. 
This nerve is homologous with the dorsal root of a spinal nerve, and the gang- 
lion radicis cochlearis, spiral ganglion of the cochlea, and vestibular ganglion 
together represent an intervertebral ganglion. On emerging from the pons the 
two roots unite to form one trunk, again dividing at the bottom of the internal 
auditory meatus. The trunk runs upward, outward, and forward round the 
middle cerebellar peduncle to the internal auditory meatus, where it becomes con- 
cave on its upper surface and lodges the facial nerve, pars intermedia, and internal 
auditory artery in the groove so formed. It is united to these structures by 
loose connective tissue, which contains no nerve-fibres. At the bottom of this 
canal it divides into an upper, vestibular division to the utricle and ampullae of 
the superior and external semicircular canals, and a lower, cochlear division to the 
saccule, ampulla of the posterior semicircular canal, and cochlea. 
Ninth, Tenth, and Eleventh Nerves. 
—The various origins, motor and sensory, of these three nerves being all con- 
tinuous columns or series of cells and fibres, they are best described together, the 
distinction between the nerves being a matter of higher or lower point of origin 
and ultimate distribution. 
Nuclei of the Ninth, Tenth, and Vagus-accessory Portion of the Eleventh Nerves. 
The sensory nucleus is an elongated column of cells mainly corresponding in 
position to the inferior fovea and trigonum vagi (or ala cinerea) in the floor of the 
fourth ventricle. It extends the whole length of the oblongata. In the lower 
part it lies dorsally to the twelfth nucleus, and dorso-laterally to the central canal; 
but as the central canal opens out into the fourth ventricle, it is shifted so as to 
lie laterally to the nucleus of the twelfth nerve, and close to the floor of the ven- 
tricle. From it bundles of fibres pass ventro-laterally to emerge from the side of 
the oblongata, between the olivary and restiform bodies, or further down between 
the last named structure and the lateral column. The upper bundles form the 
sensory fibres of the glossopharyngeal nerve, the lower are grouped into the 
pneumogastric and pars accessoria ad vagum. 
The ascending vago-glossopharyngeal root (funiculus solitarius, fasciculus 
rotundus) is a well-marked rounded bundle of fibres, which ascends on the outer 
side of the sensory nucleus from the funiculus gracilis and gelatinous substance of 
Rolando. Its main connections seem to be with the funiculi graciles of both 
sides and with the opposite fillet. It contributes fibres to the pneumogastric, but 
mainly emerges as the upper bundle of the glossopharyngeal nerve. 
The motor nucleus ( nucleus ambiguus) is a column of large multipolar cells, 
undoubtedly representing part of the ventral horn of the spinal cord. It lies 
deeply in the forraatio reticularis of the oblongata in line with the nucleus of the 
facial nerve. From it the motor roots of the three nerves under consideration 
pass in bundles, first dorsally toward the floor of the ventricle, and then outward 
and ventrally in line with the sensory bundles. 
Connection of the Vagus-accessory with the Twelfth Nucleus.—The involvement 
of the palate and vocal cords in bulbar paralysis appears to indicate that the 
motor fibres to these structures, which reach them through the vagus-accessory, 
are derived from the nucleus of the twelfth nerve. 
Nucleus of the Spinal Portion of the Eleventh Nerve.—The spinal portion of the 
spinal accessory is a purely motor nerve. It arises from a distinct column of 
cells in the ventral horn of the cervical spinal cord. From this bundles of 
nerve-fibres pass upward for a little way, then dorso-laterally through the gray NINTH OR GLOSSOPHARYNGEAL NERVE. 
591 
matter, to emerge from it at the junction of the two horns ; thence outward through 
the crossed pyramidal tract and direct cerebellar tract to their superficial origin, 
between the ligamentum denticulatuni and dorsal nerve roots. It extends as 
low as the sixth or seventh cervical nerve. 
The glossopharyngeal (“ tongue-pharynx ”) nerve (Fig. 647) is formed by the 
union of the upper live or six bundles of nerve-fibres, which arise from the side of 
the oblongata between the olivary and restiform bodies. 
It passes outward in front of the flocculus to the jugular foramen, by the 
middle compartment of which it leaves the cranium antero-internally to the 
vagus and spinal accessory, and in a special sheath of dura. In this foramen it 
lies in a groove or canal on the posterior border of the petrous bone, and here it 
possesses two successive gangliform enlargements, the jugular ganglion and 
petrous ganglion, respectively. It then passes for a short distance downward 
between the internal carotid artery and internal jugular vein, lying at first close 
to the vagus. It soon winds forward, under the styloid process and its muscles and 
superficial to the internal carotid artery, till, reaching the lower border of the 
stylopharyngeus muscle, it runs forward on it to the back of the tongue, where, 
under cover of the hyoglossus, it breaks up into its terminal branches. 
The jugular ganglion is situated at the upper margin of the jugular foramen. 
It is very small, not constant, only involves the posterior fibres of the nerve, and 
gives off no branches. It is regarded as a displaced portion of the lower ganglion, 
and together they are taken to represent the ganglion on the sensory root of a 
spinal nerve. 
The petrous ganglion lies in a groove on the petrous bone at the lower margin 
of the jugular foramen. It is not more than one-fourth of an inch long, and 
involves the whole nerve. It gives off the tympanic nerve, and twigs which 
communicate with the pneumogastric and sympathetic. 
Branches.—(rt) Meningeal branches are distributed to the pia and arachnoid 
membranes within the cranium. 
The Ninth or Glossopharyngeal Nerve. 
(6) The tympanic branch {nerve of Jacobson) is a minute but important 
nerve, which is given off from the petrous ganglion. It enters the tympanum 
through a small foramen situated on the ridge between the carotid canal and 
jugular fossa, and on the promontory divides into several branches, which form 
the tympanic plexus. Of these the principal branch pierces the roof of the 
tympanum to join the small petrosal nerve, of which it probably forms the main 
constituent. By this means glossopharyngeal fibres pass to the otic ganglion and 
so to the parotid gland. Another filament joins the great superficial petrosal 
nerve ; and a twig called the small deep petrosal nerve joins the carotid plexus of 
the sympathetic. In addition to these, filaments are distributed to the lining mem- 
brane of the mastoid cells, the fenestra, ovalls, fenestra, rotunda, and Eustachian tube. 
(c) Three communicating branches arise from the petrous ganglion, namely, 
filaments to the upper cervical ganglion of the sympathetic, the auricular branch 
of the vagus, and to the root-ganglion of that nerve. Immediately below the 
petrous ganglion a twig is given off to the lingual branch of the facial nerve. 
(d) A muscular branch is supplied to the stylopharyngeus, which also sends 
filaments to the mucous membrane of the pharynx. 
(e) Pharyngeal branches, two or three in number, spring from the nerve just 
below the petrous ganglion. The main branch passes downward over the internal 
carotid artery, and joins the pharyngeal branch of the vagus to form the pharyngeal 
plexus with the assistance of branches from the superior cervical ganglion of the 
sympathetic. 
(/) The tonsillar branches are two or three nerves which ascend under the 
hyoglossus to form a plexus on the tonsil called the circulus tonsillaris, from which 
twigs proceed to the soft palate and isthmus faucium. 592 
THE NERVES. 
(g) The lingual branches supply the posterior third of the dorsum of the 
tongue, and the side of the tongue over its posterior half, where they join the 
lingual nerve. The circu in vallate papillae receive the most minute nerve-supply. 
The posterior branches also supply the anterior surface of the epiglottis. 
Testut describes, in addition to the above, carotid branches to join the carotid 
plexus and muscular twigs to the digastric, stylohyoid, and styloglossus muscles. 
The Tenth, Pneumogastric, or Vagus Nerve. 
The tenth or pneumogastric (“lung-stomach”) nerve (Fig. 647) is formed by 
the junction of from ten to fifteen filaments, which arise from the oblongata in 
front of the restiform body and lateral tract, in series with and just below the 
roots of the glossopharyngeal nerve. 
They form together a flattened band which passes outward and a little forward 
beneath the flocculus to reach the jugular foramen, through which it leaves the 
cranium between the inferior petrosal and lateral sinuses, in the same sheath of 
dura as the spinal accessory, and external to and a little behind the glosso- 
pharyngeal nerve. In the jugular foramen its root-ganglion is found, and half 
an inch below this is a second ganglion called the ganglion of the trunk. This 
last is formed as the nerve runs downward from the base of the skull between 
the internal jugular vein and the internal carotid artery. In this situation, that 
is, immediately below the cranial base, the hypoglossal nerve winds spirally 
round the vagus, lying first internally, then passing behind and round across its 
outer side. They arc united to each other by fibrous tissue and some nerve- 
fibres which pass between the trunk ganglion and the hypoglossal nerve. Here 
also the superior cervical ganglion of the sympathetic and spinal accessory lie 
behind the vagus, and the glossopharyngeal nerve in front of it. The pneumo- 
gastric now passes downward, behind and between the internal carotid artery and 
internal jugular vein, and lower down maintains the same relation to that vein 
and the common carotid artery, being enclosed within the same fibrous sheath as 
these vessels. 
From the level of the clavicle downward the courses of the two nerves differ 
considerably, the differences, however, being readily explained by the mode of 
development of the great vessels, stomach, etc. 
The Right Pneumogastric Nerve enters the thorax by passing in front of the 
first portion of the subclavian artery, and between it and the right brachiocephalic 
vein. Bending backward to the side of the trachea, it gains the posterior sur- 
face of the root of the right lung, on which it breaks up into a coarse meshwork 
which forms, with fibres from the sympathetic, the posterior pulmonary plexus. 
From this plexus two distinct cords represent the continuation of the vagus to 
the right side of the oesophagus. 
Around this tube a new plexus is formed, called the oesophageal plexus, in 
which a free interchange of fibres occurs between the nerves of both sides. 
Again converging to form a single trunk the right vagus passes to the back 
of the oesophagus at its lower extremity, and, entering the abdomen through the 
oesophageal opening in the diaphragm behind that tube, spreads out on the poste- 
rior surface of the stomach. 
The Left Pneumogastric Nerve enters the thorax between the left common 
carotid and left subclavian arteries, and behind the left brachiocephalic vein, and 
then passing a little backward crosses the root of the subclavian artery and the 
left side of the aortic arch under cover of the pleura. Reaching the back of the 
root of the left lung, it behaves on the left side as its fellow does on the right 
side; but its terminal trunk lies in front of the oesophagus, and its final branches 
supply the front of the stomach. 
The ganglion of the root is formed within the jugular foramen and is about 
one-sixth of an inch long. It has branches by which it communicates with the 
petrous ganglion of the glossopharyngeal, the spinal accessory nerve, the superior THE TENTH, PNEUMOGASTRIC, OB VAGUS NERVE. 
593 
PNEUMOGASTRIC 
10 OR 16 BUNDLES 
GLOSSOPHARYNGEAL 
XI NERVE-j 
PARS ACCESSOR! 
4- OR B BUNDLES 
AURICULAR BRANCH 
PARS SPINALIS 
TO TRAPEZIUS 
AND 
STERNOMASTOID 
HYPOGLOSSAL 
la rynqeal 
SUPERIOR 
CERVICAL 
CARDIAC 
(TO DEEP 
CARDIAC ' 
PLEXUS) 
®EX-TERNAL LARYNGEAL 
cescjfhaqeWj ea l 
INF. CERVICAL / 
CARDIAC 
Recurrent laryngeal 
Vthoracic cardiac 
—THORACIC CARDIAC 
POSTERIOR 
PULMONARY 
PLEXUS 
-LEFT VAGUS 
CESOPHAGEAL 
PLEXUS 
DIAPHRAGM 
RIGHT VAGUS 
BEHIND 
-LEFT VAGUS IN FRONT 
LEFT VAGUS 
TO HEPATIC sa 
PLEXUS / 
RIGHT VAGUS 
TO CCELIAC, 
SPLENIC AND LEFT 
RENAL PLEXUSES 
Fig. 647.-Distribution of right pneumogastric nerve. (W. Keiller.) 594 
THE NERVES. 
cervical ganglion of the sympathetic, and two branches of distribution, namely, a 
recurrent filament to the dura and Arnold’s nerve. 
The ganglion of the trunk is fusiform in shape, one-half to three-quarters of 
an inch long, and about one-sixth of an inch thick. The spinal accessory nerve is 
closely applied to it, communicates with it by branches entering its substance, 
and contributes fibres to the pharyngeal and superior laryngeal nerves, which 
course over its outer surface. The hypoglossal nerve winds round it and com- 
municates with it. It also communicates with the superior cervical ganglion of 
the sympathetic, and with the loop between the first and second cervical nerves; 
and the pharyngeal and superior laryngeal branches of the pneumogastric are 
derived partly from this ganglion, partly from the spinal accessory. 
Branches.—(a) The communicating branches have just been sufficiently 
noticed with the two ganglia. 
(b) The recurrent branch is given off from the root-ganglion. It is distributed 
to the dura round the jugular foramen. 
(c) The auricular branch, or nerve of Arnold (Fig. 648), arises from the root- 
ganglion. After receiving a filament from the petrous ganglion of the glosso- 
pharyngeal, it passes backward on the outer 
surface of the jugular sinus, and enters a 
small canal in the jugular fossa of the 
petrous bone. In this canal it arches back- 
ward close to the inner side of the aque- 
ductus Fallopii, communicating with the 
facial nerve, and curving downward, issues 
from the temporal bone through the auricu- 
lar fissure, between the external auditory 
meatus and the mastoid process. It now 
divides into two parts, one of which joins 
the posterior auricular branch of the facial 
nerve, while the other supplies the lower 
TO EXTERNAL AUDITORY 
MEAJUSAND EWACK 
\IOF flp/ 
TWIG TO FACIAL 
AURICULAR. 
FISSURE 
FORAMEN 
TO POSTERIOR 
AURICULAR OF 
FACIAL 
JIFROM GLOSSOPHARYNGEAL 
AURICULAR BRANCH 
OF VAGUS 
7 jr I ~ 
and back part of the external auditory 
canal and the skin on the back of the 
ler )FIG'648'~Plan °f Arnold s nerve- *-w' Keil' 
pinna. 
(d) The pharyngeal branch may be single, or represented by two or three, of 
which one is usually large. It comes off from the trunk-ganglion, and is largely 
formed of fibres derived from the pars accessoria of the eleventh nerve. Running 
downward and forward superficial to the internal carotid artery, it Avinds inward 
behind the external carotid artery to the back of the pharynx, where it joins the 
pharyngeal plexus. 
(e) The superior laryngeal nerve, springing also from the ganglion of the 
trunk, is, like the last, derived largely from accessory fibres. It is much larger 
than the pharyngeal branch, and passes downward and forward on the deep sur- 
face of the internal and external carotid arteries. After receiving communicating 
branches from the superior cervical ganglion of the sympathetic and pharyngeal 
plexus, it divides into the internal and external laryngeal nerves. 
The internal laryngeal branch perforates the thyrohyoid membrane under 
cover of the thyrohyoid muscle, accompanied by the laryngeal branch of the 
superior thyroid artery. It breaks up into diverging branches which supply the 
mucous membrane on both surfaces of the epiglottis, the interior of the larynx, 
and the back of the cricoid cartilage, the descending branch forming a loop behind 
the ala of the thyroid cartilage with the recurrent laryngeal neiwe. 
The external laryngeal branch runs downward under the sternothyroid mus- 
cle to end mainly in the cricothyroid muscle, supplying on the Avay branches to 
the inferior constrictor of the pharynx, pharyngeal plexus, laryngeal mucous 
membrane, and a twig which joins one of the cardiac branches of the sympathetic. 
(/) The inferior or recurrent laryngeal nerve differs somewhat in its course on 
the two sides of the body (Fig. 649). THE TENTH, PNEUMO GAS TRIG, OB VAGUS NERVE. 
595 
On the right side it arises at the root of the neck, in front of the subclavian 
artery, winds beneath, and then upward and inward behind that vessel, and 
behind the common carotid and inferior 
thyroid arteries, to the recess between the 
oesophagus and trachea. At the lower bor- 
der of the cricoid cartilage it enters the 
pharynx by passing beneath the inferior 
constrictor. 
Under cover of the ala of the thyroid 
cartilage it divides into branches to all the 
intrinsic laryngeal muscles except the crico- 
thyroid, and to the mucous membrane of 
the larynx below the rima glottidis, joining 
the internal laryngeal nerve. 
In its course upward it gives off thoracic 
cardiac branches, twigs to the inferior cer- 
vical ganglion of the sympathetic, oesopha- 
geal and tracheal branches, and muscular 
twigs to the inferior constrictor of the 
pharynx. 
The left recurrent laryngeal nerve springs 
from the vagus as it crosses the arch of the 
aorta, winds round the concavity of the 
arch just behind the ductus arteriosus, and 
H DUCTUS Vp 
ARTERIOSUS 
Fig. 649.—Relations of pneumogastric and 
recurrent laryngeal nerves to the great vessels. 
(W. Keiller.) 
runs upward behind the origin of the left common carotid artery to reach the 
oesophagus. The rest of its course is similar to that of the right nerve. 
(g) Cervical cardiac and thoracic cardiac branches are given off by each pneu- 
mogastric nerve. There are usually two superior cervical cardiac branches, one 
inferior cervical cardiac, and two or more thoracic cardiac branches—the latter 
arising from the trunk and recurrent nerve on the right side, from the recurrent 
nerve only on the left side. These for the most part join cardiac branches of the 
sympathetic, and all, with one exception, go to the deep cardiac plexus, the left 
inferior cervical cardiac nerve being the only one which goes directly to the 
superficial cardiac plexus. 
The superior cervical cardiac nerves join the corresponding branches of the 
sympathetic beneath the carotid sheath. 
The left inferior cervical cardiac nerve descends on the left of the horizontal 
portion of the aortic arch, having the left phrenic nerve in front of it and the 
superior cervical cardiac branch of the sympathetic behind it. It joins the 
superficial cardiac plexus. 
The right inferior cervical cardiac nerve runs downward on the side of the 
brachiocephalic artery and trachea to the deep cardiac plexus. 
The right thoracic cardiac nerves, two or three in number, arise from the 
vagus trunk and from the recurrent laryngeal nerve. They run inward to the 
bifurcation of the trachea, where the deep cardiac plexus is formed. On the left 
side the thoracic cardiac branches spring from the recurrent laryngeal nerve only. 
(h) The pulmonary branches form two plexuses, one in front of and one behind 
the root of the lung. 
The anterior pulmonary plexus is small, consisting of a few filaments which 
spring from the vagus above the root of the lung, and form a meshwork in front 
of the bronchus, uniting witli sympathetic fibres from the pulmonary artery. 
The posterior pulmonary plexus is large and important, involving the whole 
trunk of the nerve. Behind the root of the lung the vagus spreads out into an 
intricate network and is supplemented by fibres from the second, third, and fourth 
thoracic ganglia of the sympathetic ; from these plexuses branches accompany 
the bronchi in all their ramifications. A free interchange of fibres takes place 
between the plexuses of the two sides. 596 
THE NERVES. 
(i) (Esophageal Branches.—Above the pulmonary plexus many small twigs 
are distributed to the oesophagus both from the trunk of the vagus and from its 
recurrent; laryngeal branch. Below that point the right and left vagi unite in 
forming a long-meshed plexus round the tube, from which its muscular and 
mucous coats get their nerve supply. 
(j) Abdominal Branches.—The left vagus distributes fibres all over the front 
of the stomach, large branches accompanying the coronary artery on its small 
curvature, and so joining the hepatic plexus of the sympathetic. The right vagus 
supplies the posterior surface of the stomach, sending branches to the coeliac, 
splenic, and left renal plexuses of the sympathetic. 
The Pharyngeal Plexus.—Two or three twigs from the superior cervical gang- 
lion of the sympathetic, the pharyngeal branches of the glossopharyngeal and vagus, 
and branches from the external and recurrent laryngeal nerves, unite in forming 
a plexus on the surface of the constrictors of the pharynx, from which the 
pharyngeal muscles and mucous membrane are supplied, as well as the levator 
palati and azygos uvulse. The motor nerves are derived from the pars accessoria. 
The Eleventh or Spinal Accessory Nerve. 
The eleventh nerve (Fig. 647) consists of two parts, an accessory portion to the 
pneumogastric (pars accessoria ad vagum) and a spinal portion (pars spinalis). 
The Accessory Portion is formed by some four or five fasciculi, which spring 
from the medulla in series with the pneumogastric roots. They unite to form 
a trunk which, with the spinal portion, to which it is united by some fibres or 
with which it may be entirely joined for a short distance, leaves the cranium in 
the same sheath of dura with the pneumogastric. In the jugular foramen it 
sends fibres to the root-ganglion of the vagus, and then partly joins the trunk- 
ganglion of that nerve; but many of its fibres are continued over the surface of 
the trunk-ganglion into the pharyngeal and superior laryngeal nerves, and down 
the vagus trunk itself into the recurrent laryngeal nerve. It will be seen that 
most of the motor fibres of the pneumogastric are derived from its accessory 
portion. 
The Spinal Portion of the spinal accessory arises by a long series of roots 
from the lateral column of the spinal cord extending as low as the sixth or 
seventh cervical nerve-roots. They issue from the lateral column between the 
attachment of the ligamentum denticulatum and the posterior nerve-roots, 
approaching closer to the latter as they ascend. They join to form an ascending 
trunk, which enters the cranium, and unites wholly or partly with the accessory 
portion ; but, beneath the jugular foramen, leaves the pars accessoria and bends 
acutely backward, usually superficially to the internal jugular vein, to enter the 
deep surface of the sternomastoid muscle, which it supplies, and where it com- 
municates with a branch from the second cervical nerve. Emerging from the 
posterior border of the sternomastoid, it crosses the posterior triangle of the neck 
obliquely to end under the trapezius, a short distance above the clavicle. On 
the deep surface of the trapezius it is joined by fibres from the third and fourth 
cervical nerves, thus forming the subtrapezial plexus, from which that muscle is 
supplied. 
The Twelfth or Hypoglossal Nerve (Fig. 644). 
The twelfth or hypoglossal (“ under the tongue ”) nerve is exclusively motor 
in function, and its nucleus lies in series with those of the third, fourth, and 
sixth nerves. Its upper part lies close to the floor of the fourth ventricle near the 
median sulcus in the elevation known as the trigonum hypoglossi; lower down it 
lies ventro-lateral to the central canal. It extends the whole length of the 
oblongata, and its cells are large and multipolar like those of the anterior horn. 
The fibres spring in two vertical series of small bundles from the ventral aspect THE TWELFTH OB HYPOGLOSSAL NERVE. 
597 
of the nucleus, and running ventrally and a little outward through the inferior 
olive (with which, however, they have no connection) emerge in a linear series 
of from ten to twelve fasciculi along the groove between the olive and anterior 
pyramid. 
Connections of the Hypoglossal.—lts main connections are as follow : 1. Com- 
missural fibres join the nuclei of the two sides; 2. Motor fibres pass from the 
nucleus of the hypoglossal by the posterior longitudinal bundle to join the pars 
accessoria ad vagum and the genu of the facial nerve of the same side; 3. Fibres 
pass to the opposite posterior longitudinal bundle. 
The roots of the twelfth nerve pass outward above the vertebral artery, and 
opposite the anterior condylar foramen pierce the dura through two distinct fora- 
mina in two bundles. In its passage through this foramen the two bundles unite 
to form one trunk, which at first lies very deeply on the inner side of the internal 
carotid artery and pneumogastric nerve. It descends in a spiral manner round 
the trunk-ganglion of the latter nerve, and between the internal jugular vein and 
internal carotid artery, being closely united to the ganglion by fibrous tissue, and 
receiving some communicating branches from it. It now appears at the lower 
border of the digastric muscle, and curves forward under the occipital artery (by 
the sternomastoid branch of which vessel it is kept in place) and across the exter- 
nal carotid artery. It reaches the upper border of the great cornu of the hyoid bone, 
where it lies on the middle constrictor of the pharynx and above the lingual artery. 
Passing under cover of the posterior belly of the digastric and the stylohyoid 
muscles, it lies on the hyoglossus muscle just above the central tendon of the 
digastric. Here it is accompanied by the lingual vein, and is separated from the 
lingual artery by the hyoglossus. Passing beneath the mylohyoid, it curves 
upward on the genioglossus, communicating in a loop with the lingual nerve and 
terminating beneath the tip of the tongue. 
The branches of this nerve are divisible into two sets, namely, true hypoglossal 
branches which are distributed exclusively to the extrinsic and intrinsic muscles 
of the tongue, and branches which are really derived from the cervical plexus, 
and are only adherent to the hypoglossal nerve for some part of their course. 
True Hypoglossal Branches.—(a) Communicating branches unite the 
hypoglossal nerve with the trunk-ganglion of the vagus and superior cervical 
ganglion of the sympathetic, and in a manner to be explained later, with the 
loop between the first and second cervical nerves. At the tip of the tongue it 
communicates with the lingual nerve, and a small twig, called the lingual branch 
of the vagus, joins it from the pharyngeal plexus. 
(b) The meningeal branch is given off in the anterior condylar foramen, and 
enters the cranium to supply the dura round the foramen magnum and diploe of 
the occipital bone. 
(c) Muscular branches are distributed beneath the mylohyoid to the hyoglossus, 
styloglossus, and genioglossus, and also to the intrinsic muscles of the tongue. 
Branches of the Cervical Plexus Adherent to or Associated 
with the Hypoglossal Nerve (Fig. 656).—A considerable branch from the 
loop between the first and second cervical nerves joins the hypoglossal just beneath 
the base of the cranium. It is incorporated with the hypoglossal nerve till it 
winds round the occipital artery, where part of the cervical branch leaves the 
hypoglossal under the name of the descendens hypoglossi. A smaller branch is 
given off lower down to supply the thyrohyoid muscle, and the remainder of this 
cervical nerve accompanies the hypoglossal under the mylohyoid to supply the 
geniohyoid muscle. 
The descendens hypoglossi springs from the trunk of the twelfth nerve where it 
crosses the occipital artery, and passes downward and a little forward on the 
sheath of the great vessels and beneath the sternomastoid for a variable distance, 
but usually to nearly on a level with the cricoid cartilage. Here it forms a loop 
with the ramus cervicalis descendens (communicans hypoglossi), which is formed by 
the union of two branches from the second and third cervical nerves respectively. 598 
THE NER VES. 
This loop is called the ansa hypoglossi. From the descendens hypoglossi a 
twig is given to the anterior belly of the omohyoid. From the loop, branches are 
given to the sternohyoid, sternothyroid, and posterior belly of the omohyoid, the 
last twig passing backward through the loop of deep cervical fascia, which binds 
down the central tendon of its muscle. The nerves to the sternohyoid and sterno- 
thyroid enter the posterior borders of these muscles low down, and may extend 
into the thorax and communicate with the phrenic nerve. 
THE SPINAL NERVES. 
In introducing the subject of the cranial nerves we entered pretty fully into 
the mode of formation of a spinal nerve, taking it as the type on which the 
.internal branch 
BRANCH 
'POSTERIOR PRIMARY 
DIVISION 
ANTERIOR PRIMARY 
DIVISION 
RAMUS COMMUNICANS 
Fig. 650.—Plan of the constitution of a spinal nerve. (W. Keiller.) 
cranial nerves, also, are more or less closely planned. We refer the student again 
to page 563, and here supplement what 
is there said by additional matter neces- 
sary to the present subject. 
Fig. 650 illustrates the mode of origin 
and constitution of a spinal nerve. It 
is seen to spring from the spinal cord by 
two roots, ventral and dorsal. 
dorsal] 
NERVE 
ROOTS J 
(VENTRAL 
| NERVE 
I ROOTS 
DORSAL 
ROOTS " 
LIGAMENTUM 
,DENTICULATU M 
DURA 
The ventral root is motor in function, 
and springs from the ventro-lateral aspect 
of the cord by from four to six bundles. 
They unite to form two strands, which 
enter a sheath of dura, in which they 
are at first separated from the dorsal 
root by a fibrous septum. Within the 
sheath and as they traverse the inter- 
vertebral foramen, the ventral root unites 
with the dorsal to form a spinal nerve. 
The dorsal roots, usually larger than 
the ventral, are sensory in function, and 
spring from the dorso-lateral aspect of 
the cord by from six to eight fasciculi, 
which with their fellows are arranged in 
a single linear series all down the cord. 
They unite to form two bundles and 
within the dural sheath enter a ganglion, 
from which they emerge as one bundle, 
and immediately join the ventral root to 
form a spinal nerve. 
.VENTRAL 
ROOTS 
SPINAL NERVE 
IN ITS RIAL 
SHEATH 
DORSAL 
ROOTS " 
VENTRAL 
ROOTS 
LIGAMENTUM 
DENTICULATUM 
VENTRAL ROOTS 
DORSAL 
ROOTS 
SPINAL NERVE 
IN ITS SHEATH 
fig. 651.—a portion of the spinal cord, showing 
its right lateral surface. The dura is opened and 
arranged to show the nerve-roots. (Testut.) 
A spinal ganglion is an ovoid body, 
i -nj . py+TOmitr wLaro ffio 
tuna at its proximal exti entity wtiere me THE SPINAL NERVES. 
Serves motor sensory reflexes, 
v _ . _____ DISTRIBUTION, AREAS. 
J- NECK AND SCALP 
-1-8- 
mm. 
SUPRASPINATUS* 
INFRASPINATUS 
TERES MINOR, f 
NECK AND 
SHOULDER. 
-25- 
mm. 
BICEPS. BRACHIALI3. 
DELTOID. BRACHIO- 
RADIALIB. SUPINATOR 
SUBSCAP.- PRONATORS. 
TER. MAJ. LATISS. PECT 
MAJ. TRICEPS.SERR.MAG 
EXTENSORS OF WRIST. 
SHOULDER. 
► ARM. 
FLEXORS OF THE WRIST 
HAND— 
SCAPULAR 
-33- 
mm. 
INTEROSSEI AND OTHER 
INTRINSIC MUSCLES OF 
JHAND. 
FRONT OF 
'"thorax. 
-4-7 
mm. 
INTERCOSTAL 
* MUSCLES. 
:pigastric. 
/ENSIFORM AREA. 
-68- 
mm. 
ABDOMINAL 
MUSCLES. 
ABDOMEN. 
UMBILICUS (10th) 
>ABDOMINAL. 
-111- 
mm. 
114 
mm. 
NONE 
ILIOHYPOGASTRIC AND 
ILIO-INGUINAL. 
138 
mm. 
NONE 
OUTER AND UPPER PART 
OF THIGH. 
>CREMASTERIC. 
151 
mm. 
SARTORIUS, ADDUCTORS ANTERIOR ASPECT OF 
AND FLEXORS OF THIGH. THIGH BELOW SECOND 
LUMBAR ROOT. 
163 
mm. 
EXTENSORS OF KNEE d ANTERIOR AND INNER 
ABDUCTORS OF THIGH. ASPECT OF LEG. 
I. KNEE 
[ JERK. 
181 
mm. 
HAMSTRING MUSCLES. 
BACK OF THIGH, EXCEPT 
IN DISTRIBUTION OF 
IST, 2ND d 3RD SACRAL. 
188 
mm. 
|CALF MUSCLES,GLUTEI 
I PERONEI. ANTERIOR 
>GROUP OF LEG MUS- 
ICLES. INTRINSIC MUSC- 
ILES OF FOOT. 
rGLUTEAL, 
NARROW STRIP ON 
BACK OF THIGH, LEG 
AND ANKLE; SOLE; 
PART OF DORSUM OF 
FOOT. 
PERIN/EAL MUSCLES 
ERECTOR PENIS.TRANS. 
PERIN. ACCEL. URIN.d C. 
PERIN/EUM, EXT. GENI- 
TALS; SADDLE SHAPED 
AREA OF BACK OF THIGH. 
FOOT CLONUS. 
PLANTAR. 
280 
mm. 
Fig. 652.—Topography and distribution of the spinal nerve-roots, 600 
THE NERVES. 
two bundles of dorsal nerve-roots enter it. It consists of bipolar nerve cells, 
one pole or process of each cell forming the peripheral portion of a sensory nerve 
fibril, the other pole or process forming its central continuation. With the excep- 
tions to be mentioned, they are placed in the intervertebral foramina immediately 
beyond the point where the roots enter the dural sheath provided for them by 
the theca vertebralis. 
The ganglia of the first and second cervical nerves lie on the laminae of the 
atlas and axis respectively ; those of the sacral and coccygeal nerves are found 
within the spinal canal, at a variable distance from their points of emergence 
from it. 
The course of the nerve-roots within the spinal canal varies considerably at dif- 
ferent levels, the growth of the spinal cord not being equal to that of the verte- 
bral column; for, while the cord occupies the whole length of the canal in the 
foetus, it only reaches as low as the body of the first lumbar vertebra in the adult. 
Thus the first spinal nerve ascends slightly to reach the space between the atlas 
and occipital bone, through which it leaves the spinal canal; the second and 
third are nearly horizontal; the fourth runs obliquely downward and outward 
and the obliquity of the others within the vertebral canal steadily increases from 
here downward till the nerve-roots of the lumbar and sacral nerves run vertically 
downward for an increasing distance, thus forming the cauda equina. This will 
be easily appreciated by a glance at Figures 652 and 653. 
Topographical Anatomy of the Cord and Spinal Nerve-roots (Fig. 652).—It is 
important for surgical purposes to determine the relationship between the bony 
landmarks furnished by the spines of the vertebrae, and the superficial origins 
of the spinal nerves. The main surgical data are graphically described in Fig. 
652. The brackets in column A show the extreme limits between which in dif- 
ferent subjects examined by Reid each group of nerve-roots was found to arise. 
B shows each nerve cut off at the level of its intervertebral foramen, thus afford- 
ing a ready estimate of the obliquity of its course in the neural canal; C gives 
the vertical distance in millimeters which in Testut’s case of a subject of eighteen 
years of age separated the superficial origin of each of the nerves marked from 
its intervertebral foramen; and the other columns will be readily intelligible to 
the senior student. It is be noted that the distribution marked in D, E, and Fis 
only broadly true and does not pretend to anatomical minuteness; but it is for 
that reason all the more valuable for clinical purposes. 
Nomenclature (Fig. 653).—There are thirty-one pairs of the spinal nerves, 
namely, eight cervical, twelve thoracic, five lumbar, five sacral, and one coccygeal. 
It will be noted that these numbers correspond with the number of vertebrae in 
each region except the cervical nerves, which are one in excess. The first cervical 
nerve leaves the vertebral canal above the dorsal arch of the atlas, between it 
and the occipital bone ; the eighth passes through the intervertebral foramen 
between the seventh cervical and first thoracic vertebrae. Thus the first seven 
cervical nerves are named from the vertebrae below them; the eighth cervical 
has no corresponding vertebra, and the thoracic, lumbar, and other nerves are 
named from the vertebrae above them. 
Mode of Distribution.—A spinal nerve, formed as above by the union of a 
motor and a sensory root, is a short trunk, which, immediately after its exit from 
the intervertebral foramen, gives off a small recurrent branch, and then divides 
into a ventral and a dorsal primary division (Fig. 650). 
The dorsal primary divisions, except those of the first and second cervical 
nerves, are smaller than the ventral. They pass backward and divide into two 
branches, external and internal. They supply the skin of the back of the head, 
neck, trunk, and gluteal region, and the muscles which act directly upon the 
spinal column. 
The ventral primary divisions, with the two exceptions above mentioned, are 
larger than the posterior. Each ventral division is joined by one or two branches 
from the neighboring sympathetic ganglion by which it receives non-medullated THE SPINAL NERVES. 
601 
fibres for distribution to the vessels which it innervates, and contributes medullated 
fibres to the sympathetic trunk. The ventral primary divisions of the thoracic 
nerves (except the first) form intercostal nerves, and are distributed each to its 
own area, but in all the other 
regions intricate plexuses are 
formed by neighboring nerves 
before their branches of dis- 
tribution are given oif. 
PONS 
ACCESSORY 
SPI NAL 
The recurrent branch is a 
small twig given off from the 
nerve immediately after it 
leaves the intervertebral fora- 
men. It receives a communi- 
cation from the sympathetic 
and re-enters the spinal canal 
to supply the meninges and 
blood-vessels. 
C SUPERIOR CERVICAL 
-< GANGLION OF SYM- 
( PATHETIC 
Z E R VI CAL 
PLEXUS 
NERVES ' 
MIDDLE CERVI- 
CAL GANGLION 
BRACHIAL 
PLEXUS 
Dorsal Primary Divisions 
of the Spinal Nerves.— General 
Statement.—The dorsal primary 
divisions of the spinal nerves 
(Fig. 654) are destined for the 
supply of the skin of the back 
of the scalp, trunk, and gluteal 
region, and the muscles of the 
posterior spinal group, except 
those connected with the upper 
limb, the serrati posteriores, 
and the levatores costarum. 
With the few exceptions men- 
tioned below, each nerve passes 
backward between the trans- 
verse processes of the adjacent 
vertebrae and spinal muscles, 
dividing into an internal and 
an external branch. From 
the sixth thoracic nerve up- 
ward the internal branches 
are larger and are mainly cuta- 
neous, the external branches 
are smaller and purely mus- 
cular ; below that point the 
arrangement is reversed, the 
external branches being the 
larger, and mainly distributed 
to the skin, the internal 
branches small and chiefly dis- 
tributed to the erector spinae 
and deeper spinal muscles. 
Exceptions to this general 
type are as follow : 
INFERIOR CERVI 
CAL GANGLION 
LU M BAR 
PLEXUS s 
'LUMBAR/ 
NERVES! 
>LU M BAR GANGLIA 
iSACRAL 
'ganglia 
/ SACRAL| 
NERVES ' 
SACRA 
PLEXUS 
COCCYGEAL/ 
PLEXUS 
-The dorsal primary divis- Fig. 653.—Anterior surface of the spinal cord, showing the 
ion Of the first cervical (sub- o^oneTde!8 connections with the sympathetic trunk 
occipital) nerve does not 
divide, is usually purely muscular, and requires special description. 
The dorsal divisions of the fourth and fifth sacral nerves and the coccygeal 
nerve do not divide, but form loops with each other, and are purely cutaneous. 602 
THE NERVES. 
The dorsal divisions of the sixth, seventh, and eighth cervical nerves divide 
like the others into internal and external branches; but both these branches are 
distributed to muscles only. 
The Dorsal Primary Division of the First Cervical or Suhoccipital Nerve (Fig. 
655).—The first cervical or suhoccipital nerve leaves the cranio-vertebral canal 
by passing between the occipital bone and the dorsal arch of the atlas. The 
dorsal division, slightly larger than the ventral, passes backward under the ver- 
tebral artery, and enters the suhoccipital triangle. This space is bounded by the 
rectus capitis posterior major internally, the obliquus inferior infero-externally, 
and the obliquus superior supero-externally. Here the nerve divides into the 
RAMIFICATIONS IN 
OCCIPITAL REGION 
ANASTOMOSIS WITH MASTOID 
BR. OF CERVICAL PLEXUS 
GREAT OCCIPITAL 
THIRD.... 
CERVICAL 
SMALL OCCIPITAL 
(from cervical plexus) 
4TH, STH AND 6TH 
CERVICAL 
UPPER THORACIC ) 
(internal divisions) I 
EXTERNAL DIVISION 
OF LOWER THORACIC" 
EXTERNAL DIVISION 
OF LOWER THORA- 
CIC 
.EXTERNAL BRANCHES 
OF LUMBAR 
SACRAL' 
Fig. 654.—Dorsal primary divisions of the spinal nerves. (Testut.) 
following four branches : (a) a branch to the obliquus inferior which furnishes an 
anastomotic filament to the great occipital nerve; (6) a branch running upward 
to the recti capitis posteriores major and minor; (c) a third branch enters the 
obliqnus superior; (d) and a fourth branch supplies the complexus on its deep 
surface. 
The Great Occipital Nerve (Figs. 654, 655).—The dorsal primary division of 
the second cervical nerve is three or four times as large as the ventral division. Its 
external branch is small and is distributed to the inferior oblique, complexus, and 
trachelomastoid; but the internal branch is large, and from its size and distribu- 
tion is called the Great Occipital Nerve. After communicating with the first and THE ANTERIOR PRIMARY DIVISIONS. 
603 
third cervical nerves, and thus forming what has been called the dorsal cervical 
plexus, it winds upward over the obliquus inferior, supplies a twig to the com- 
plexus, and then pierces it and the trapezius to become cutaneous beneath the superior 
curved line of the occipital bone, about one inch from the middle line. Accom- 
panied by branches of the occipital artery, it supplies the skin over the upper 
GREAT OCCIPI 
TAL NERVE 
OBLIQUUS 
SUPERIOR 
RECTUS CAPITIS 
LATERALIS 
BRANCH TO COMPLEXUS—CUT 
ANTERIOR PRIMARY DIVI- 
SION OF FIRST CERVICAL 
•POSTERIOR PRIMARY DIVI- 
SION OF FIRST CERVICAL 
■ANASTOMOTIC BRANCH 
-VERTEBRAL ARTERY 
VERTEBRAL ARTERY, 
—CUT 
ANASTOMOTIC 
-THIRD CERVICAL 
POSTERIOR PRIMARY DIVI- 
SION OF FIRST CERVICAL L 
OBLIQUUS 
) IN FERIOR 
Fig. 655.—Dorsal primary divisions of the upper three cervical nerves. (Testut.) 
RECTUS 
MAJOR 
part of the occipital bone and posterior parietal region, interlacing with the small 
occipital externally, and with the cutaneous branch of the third cervical nerve 
(third occipital nerve) internally. 
The Third Occipital Nerve.—The internal branch of the dorsal division of the 
third cervical nerve is directed upward beneath the complexus to reach the skin 
of the occiput internally to the great occipital, with which it communicates. Its 
distribution has led to its being called the third occipital nerve. 
The Anterior Primary Divisions. 
CERVICAL NERVES. 
The upper four cervical nerves unite to form the Cervical Plexus, and supply 
the skin and muscles of the neck. The lower four unite with the first thoracic 
nerve to form the brachial plexus by which the upper limb is supplied. 
The Cervical Plexus (Fig. 656). 
The first cervical nerve (ventral division), after leaving the vertebral canal in 
the groove on the dorsal arch of the atlas, winds round to the front on the inner 
side of the vertebral artery and bends downward over the transverse process 
to join the second nerve. The ventral division of the second nerve leaves the 
vertebral canal behind the articular process of the axis ; those of the rest of the 
cervical nerves pass outward in the intervertebral foramina, behind the vertebral 
artery and between the rectus capitis anterior major and the scalenus medius. 
On the surface of the levator scapulae and scalenus medius, and under cover 
of the sternomastoid these four nerves form three loops; and from these loops, 
or from the nerves themselves, spring the branches of the plexus. These are 
divisible into a superficial cutaneous set, and a deep series, including muscular 
and communicating nerves. 604 
THE NEB VES. 
Superficial Branches (Fig. 645).—These are ascending, transverse, and 
descending. 
ASCENDING BRANCHES. 
1. The Small Occipital Nerve is derived from the second cervical nerve. It 
passes backward under the sternomastoid muscle to its dorsal border, then upward 
along that border, dividing at about the level of the mastoid process into an 
auricular branch to the skin of the dorsal and upper part of the pinna, a mastoid 
branch to the skin over the mastoid region, and an occipital branch to the occipital 
area. It communicates with the great auricular and great occipital nerves. 
R.C.A. MIN. 
A. MAJ. 
R.U 
TOVAGUSC 
COMMUNICATING TO 
HYPOGLOSSAL 
SYMPATHETIC 
. LONGUS COLL. & 
RECTUS ANT. MAJOR 
TO GENIOHYOID 
\ TO THYROHYOID 
/ STERNO / 
I MASTOID/^ 
SUBMANDIBULAR 
BR. OF FACIAL 
LEVATOR ANGULI SCAR 
& SCALENUS MEDIUS 
Lq\ 
SWERF\IkVAL 
i-FROM SYMPATHETIC 
TRAPEZIUS 
Fig. 656.—-Plan of cervical plexus. 
2. The Great Auricular Nerve springs by two roots from the second and third 
cervical nerves. Reaching the dorsal border of the sternomastoid, it crosses it 
diagonally in running upward to the back of the auricle. It supplies a small 
mastoid branch to join the mastoid branches of the small occipital nerve, numer- 
ous large auricular branches to the back of the pinna in its lower two thirds, one 
or two of these piercing the cartilage to the front of the lobule and helix; and a THE CERVICAL PLEXUS. 
605 
small facial branch to the skin of the parotid, masseteric, and buccal regions 
These branches join the facial nerve. 
TRANSVERSE BRANCH. 
The Superficial Cervical Nerve, rising with the last from the second and third 
cervical nerves, curves round the dorsal border of the sternoraastoid muscle about 
its middle and spreads out into branches, which ramify between the platysraa and 
deep fascia over the carotid triangle. Its ascending branch forms one or more 
loops with the inframandibular branch of the facial nerve. It supplies the skin 
of the front of the neck from chin to sternum. 
DESCENDING BRANCHES. 
Branches from the third and fourth nerves form a large trunk, which pierces 
the deep fascia at the dorsal border of the sternomastoid and just below its mid- 
dle. This soon divides into three or four branches, which descend between the 
platysma and deep fascia to the skin of the sternal, clavicular, and acromial 
regions respectively, and are named according to that distribution. 
Muscular branches to the trapezius are usually associated with this trunk. 
Deep Branches.—The deep branches may be conveniently divided into 
muscular and communicating. 
Muscular Branches are distributed to the rectus capitis lateralis and recti ante- 
riores from the loop between the first and second nerves. A branch to the sterno- 
mastoid from the second nerve enters the under surface of that muscle near 
the mastoid process, and there communicates with the spinal accessory nerve. 
From the second and third nerves two branches join to form the ramus cervi- 
calis descendens, already described with the hypoglossal nerve. It supplies the 
depressors of the hyoid bone. From these nerves also twigs pass to the longus 
colli. The levator scapulse receives two or three branches from the third and 
fourth nerves, and the scalenus medius receives branches from the same trunks. 
Branches to the trapezius are derived from the descending cutaneous trunk (third 
and fourth nerves), and these unite under the trapezius with the termination of 
the spinal accessory nerve, thus forming the suhtrapezial plexus. 
The phrenic nerve is the most important branch of the cervical plexus. Its 
most constant root is from the fourth nerve, but it may have other roots from the 
third or fifth, or both. Where the root from the fourth nerve is absent, it usually 
receives a twig from the nerve to the subclavius. In addition to these, it receives 
a communication from the cervical sympathetic. It takes a very constant and 
definite course downward and forward over the scalenus anterior, and beneath the 
omohyoid muscle and transversalis colli and suprascapular arteries, and, on the left 
side, the thoracic duct. Passing behind the subclavian vein it enters the thorax, 
the internal mammary artery crossing behind it to reach the sternum. On the 
right side it now descends on the outer side of the right brachio-cephalic vein, 
superior cava, and pericardium in front of the root of the lung and between these 
structures and the pleura, to the diaphragm, which it pierces and supplies on its 
abdominal surface. On the left side it crosses the second part of the arch of the 
aorta and descends on the pericardium in front of the root of the lung to the 
diaphragm, being covered, of course, by pleura. 
Branches.—Twigs are supplied to the pleura and pericardium, and on the 
right side it communicates with the diaphragmatic plexus of the sympathetic, 
forming a small ganglion. 
Communicating Branches of the Cervical Plexus.—From the loop between the 
first and second nerves branches pass to the vagus and hypoglossal, the branch to 
the hypoglossal being destined for hyoid muscles. The muscular branches from 
the second to the sternoraastoid and from the third and fourth to the trapezius 
communicate with the spinal accessory; and each nerve is connected with the 
superior cervical ganglion of the sympathetic. 606 
THE NERVES. 
The Brachial Plexus (Fig. 657). 
Tiie anterior primary divisions of the fifth, sixth, seventh, and eighth cervical 
nerves join with the first thoracic nerve to form the brachial plexus. Com- 
munications are also received from the fourth cervical and second thoracic nerves. 
The cervical nerves emerge from the grooves on the transverse process of the 
FIFTH 
CERVICAL' 
—FROM FOURTH CERVICAL 
SIXTH 
LEVEL OF THE 
CLAVICLE 
-TO PHRENIC 
VUPPER TRUNK 
TO SCALENI & 
LONGUS COLLI 
SEVENTH( 
U 
—NERV ErO SUBCLAVIUS 
EIGHTH\ 
2)SUPRASOAPULAR 
I EXTERNAL ANTERIOR THORACIC 
FIRST 
THORACIC 
"VLOWPR— 
tru-Kik 
--INTERNAL ANTERIOR THORACIC 
—CIRCUMFLEX 
SECOND; 
-MUSCULO SPIRAL 
THIRD 
POSTERIOR 
THORACIC 
Fig. 657.—Plan of brachial plexus. 
vertebrae, between the scalenus medius and anterior, and run downward in front 
of the former muscle. The first thoracic nerve emerges from between the first 
and second thoracic vertebrae, gives off a small branch to the first intercostal 
space, and ascends over the first rib to join the eighth cervical nerve. On the 
surface of the scalenus medius three primary trunks are formed, the fifth and 
sixth nerves uniting to form the upper trunk, the seventh alone forming the mid- 
dle trunk, and the eighth cervical and first thoracic nerves forming the lower 
trunk. These run together downward and outward in the subclavian triangle 
above the subclavian artery. In this situation each trunk splits into an anterior 
and posterior division. The anterior divisions of the two upper trunks unite to 
form the outer cord ; the inner cord is the continued anterior division of the 
lower trunk; and the three posterior divisions together form the posterior cord. 
These three cords lie to the outer side of the first part of the axillary artery, dis- 
tribute themselves round its second part in such positions as their names designate, 
and at the level of the third part of the vessel each cord has divided into separate 
nerves, which bear to the artery the same relations as the cords from which they 
spring. 
This is the usual arrangement, but there are numerous variations, 
v The branches of the brachial plexus are classified into supraclavicular and 
infraclavicular. 
Branches Given off Above the Clavicle. 
1. The nerve to the rhomboids (5. c.) is a long slender branch which springs 
from the fifth cervical nerve, close to the intervertebral foramen and in common 
with the first root of the posterior thoracic nerve. It enters the substance of the BRACHIAL PLEXUS. 
607 
scalenus medius and emerges from its external border. Passing beneath the 
levator scapulae, it supplies some twigs to that muscle, and reaches the deep sur- 
face of the rhomboids, where it is joined by the posterior scapular artery. It 
ends in the rhomboid muscles. 
2. The nerve to the subclavius (5. c.) springs from the upper trunk. As a 
long slender filament it descends in front of the plexus and subclavian artery to 
supply the muscle from which it is named. It frequently contributes a filament 
to the phrenic nerve. 
3. The suprascapular nerve (5. c.) (Fig. 658), also derived from the upper 
trunk, runs downward, outward, and backward over the scalenus medius and 
under the trapezius and omohyoid. It passes through the suprascapular notch, 
beneath the transverse ligament, and, after supplying a twig to the shoulder-joint, 
SUPRASCAPULAR 
SUPERIOR BRANCH 
OF CIRCUMFLEX 
INFERIOR BRANCH 
OF CIRCUMFLEX 
CUTAN EOUS 
:BRANCHES 
Fig. 658.—Suprascapular and circumflex nerves of right side, seen from behind. (Testut.) 
divides into branches to the supraspinatus and infraspinatus, the former turning 
outward into its muscle, and the latter passing round the great scapular notch, 
and terminating in the infraspinatus. 
4. The posterior thoracic nerve (5. 6. 7 ? c.) (external respiratory nerve of Bell) 
is formed by the union of three roots, from the fifth, sixth, and seventh nerves 
respectively. The first two roots pierce the scalenus medius and supply twigs to 
the upper digitations of the serratus magnus. They are afterward joined by the 
seventh root, which passes in front of the scalenus medius. The nerve descends 
behind the brachial plexus and the first portion of the axillary artery, and runs 
along the chest wall on the serratus magnus, rather behind the lateral prominence 
of the ribs, sending a twig to each digitation of that muscle. 
5. The scaleni and longus colli are supplied by twigs from the lower three 
cervical nerves. # 
Branches Given off below the Clavicle. 
Of these the external and internal anterior thoracic and three subscapular 
nerves are distributed to parts about the axilla; the rest supply the arm and 
forearm. 608 
THE NERVES. 
1. External Anterior Thoracic Nerve (6. 7. c.) springs from the outer cord, 
pierces the costo-coracoid membrane above the pectoralis minor, and supplies the 
pectoralis major. 
2. The Internal Anterior Thoracic Nerve (8. c., 1. th.) is derived from the inner 
cord. It passes forward between the axillary artery and vein, and enters the 
deep surface of the pectoralis minor. After supplying this muscle, it pierces it 
to reach the pectoralis major, in which it ends. Thus the pectoralis major is sup- 
plied by two nerves. 
These two nerves are usually united by a loop which crosses in front of the 
axillary artery. 
3. The Subscapular Nerves supply the muscles which form the posterior 
axillary wall, and are all branches of the posterior cord. 
The upper subscapular (5. 6. c.), sometimes represented by two branches, lies 
high in the axilla. It is very short and plunges at once into the upper part of 
the subscapularis. 
The middle or long suhscapular nerve (7. c.) accompanies the subscapular 
artery and supplies the latissimus. 
The lower subscapular nerve (5. 6. c.) sends twigs to the lower part of the 
subscapularis muscle and ends in the teres major. 
Terminal or Long Branches.—The outer cord divides into the musculo- 
cutaneous and outer head of the median ; the inner cord, into the small internal 
cutaneous, internal cutaneous, ulnar and inner head of the median, and the poste- 
rior cord into the circumflex and musculo-spiral. These branches are arranged 
around the third part of the axillary artery in the same manner as their parent 
cords, except that the small internal cutaneous nerve is separated from the artery 
by the axillary vein, and the internal cutaneous nerve and inner head of the 
median lie in front of the vessel. 
4. The Musculo-cutaneous Nerve. 
The musculo-cutaneous nerve (5. 6. c.) (Figs. 659, 666, 667), arising from 
the outer cord of the plexus, lies first on the outer side of the axillary and after- 
ward of the brachial artery. It sends some fibres to the coraco-brachialis, and 
its main trunk perforates that muscle in a downward and outward direction near 
the lower border of the axilla. Passing obliquely across the arm between the 
biceps and brachialis anterior it gives branches to both these muscles, and reaches 
the surface at the outer border of the biceps a little above the bend of the elbow. 
Here it perforates the deep fascia, and divides into an anterior and a posterior 
division, which supply the skin on the anterior and posterior aspects of the 
radial side of the forearm. Of these the anterior division is large, and reaches 
as far down as the thenar eminence ; the posterior division is shorter and only 
reaches as low as the wrist. Both divisions communicate with the radial nerve. 
At the bend of the elbow the nerve is crossed by the median cephalic vein. 
5. The Median Nerve. 
The median nerve (6. 7. 8. c., 1. th.) (Figs. 659, 660, 661, 663, 666, 667) arises 
by two heads, one from the inner and one from the outer cord. The inner head 
crosses in front of the third part of the axillary artery to join the outer head, and 
the resulting nerve runs down the arm on the outer side of the axillary and 
brachial arteries, and slightly under cover of the biceps. Near the middle of 
the humerus it crosses in front of the brachial artery to reach its inner side, which 
it keeps till the vessel bifurcates. It then passes between the two heads of the 
pronator teres, crossing the ulnar artery but separated from the vessel by the 
ulnar head of the muscle, and courses down the middle of the forearm on the 
flexor profundus digitorum under the flexor sublimis. At the wrist it is found 
beneath the deep fascia between the flexor sublimis and flexor carpi radialis and THE MEDIAN NEB VE. 
609 
just to the outer side or under cover of the palmaris longus. It now passes 
beneath the anterior annular ligament, where it is invested by the synovial mem- 
brane, and whence it emerges as a flattened band and divides into inner and outer 
terminal divisions. 
Branches.—The median nerve gives no branches to the upper arm, but 
supplies the elbow-joint, all the anterior group of forearm muscles, except the 
.INNER CORD 
SMALL INTERNAL 
CUTANEOUS 
OUTER HEAD 
OF MEDIAN ' 
-INTERNAL CUTANEOUS 
...NERVE TO COR ACO - BRACHIALIS 
-ULNAR 
INNER HEAD OF MEDIAN 
CIRCUM FLEX- 
MEDIAN 
MUSCULO-CUTA 
NEOUS 
TO BRACHIALIS 
BRANCH TO.. 
BRACHIALIS 
-TO BICEPS 
ULNAR 
EXTERNAL CUTANEOUS 
OF MUSCULO-SPIRAL 
TO BRACHIAL 
ARTERY 
MUSCULO-SPIRAL- 
TO PRONATOR 
TERES 
TO EXTENSOR CARPI_ 
RADIALIS LONGUS 
TO BRACHIO-RADIALIS" 
TO PALMARIS 
LONGUS 
POSTERIOR BRANCH OF « |aNTERIOR BRANCH OF 
MUSCULO-CUTANEOUS MUSCULC-CUTANEOUS 
Fig. 659.—Deep nerves of the front of the right arm. (Testut.) 
flexor carpi ulnaris and half of the flexor profundus, and the short muscles of the 
thumb that are on the radial side of the flexor longus pollicis. Its cutaneous 
branches supply the hollow of the palm, the thumb, index, middle and half of 
the ring fingers on their palmar aspect and nail-beds, and the two outer lumbrical 
muscles. 610 
THE NERVES. 
Muscular Branches.—The branch to the pronator teres (6. c.) is given off just 
above the bend of the elbow, those for the palmaris longus (7. 8. c., 1. th.), 
flexor carpi radialis (6. c.), and flexor sublimis digitorum (7. 8. c., 1. th.) a little 
lower down. 
The anterior interosseous nerve (7. 8. c., 1. th.) (Figs. 660, 663) is the muscular 
-MEDIAN 
—ULNAR 
BRANCH TO PRC 
' NATOR TERES 
POSTERIOR 
INTEROSSEOUS1" 
( BRANCH TO PALMARIS 
< LONQUS AND FLEXOR 
( OARPI RADIALIS 
fBRANCH TO FLEXOR 
(_ SUBLIMIS 
ANTERIOR 
INTEROSSEOUS 
RADIAL— 
DORSAL CUTANEOUS 
BRANCH 
PALMAR CUTANEOUS 
BRANCH OF MEDIAN 
.PALMAR CUTANEOUS 
BRANCH 
DEEP TERMINAL 
BRANCH 
SUPERFICIAL TER 
' MINAL BRANCH 
-TERMINAL BRANCHES 
Fig. 660.—Deep nerves of the front of the right forearm. (Testut.) 
branch of the median to the deep muscles of the forearm. Commencing 
opposite the bicipital tuberosity of the radius, it accompanies the anterior 
interosseous artery and lies on the interosseous membrane between the flexor pro- 
fundus digitorum and flexor longus pollicis. It supplies branches to both these 
muscles, that to the flexor profundus communicating with the corresponding 
branch of the ulnar nerve. The nerve accompanies the artery under the pronator 
quadratus; but, instead of following the vessel through the interosseous mem- THE MEDIAN NEB VE. 
611 
brane to the back, terminates by supplying the pronator quadratus and wrist 
joint. 
The muscular branch to the abductor pollicis, flexor ossis metacarpi pollicis, 
and outer head of the flexor brevis pollicis is a short, stout twig derived from the 
external terminal division. 
The Cutaneous Branches of the median are the palmar cutaneous and two 
terminal divisions. 
The palmar cutaneous branch is a small twig given off above the anterior 
annular ligament. It crosses in front of that ligament and supplies the palm and 
RADIAL— 
I ULNAR 
POSTERIOR BRANCH 
OF RADIAL 
MEDIAN- 
ANTERIOR BRANCH- 
OF RADIAL 
PALMAR CUTAN EOUSj 
OF MEDIAN M 
_JDEEP BRANCH 
OF ULNAR 
MUSCULAR TO ABDUCTOR 
OPPONENS, AND FLEXOR 
BREVIS POLLICIS 
SUPERFICIAL BRANCH 
OF ULNAR 
COLLATERALS 
TO THUMBy 
COMMUNICATING 
MEDIAN 
/ \NERVE TO 
FIRST ) 
LUMBRICAL ) 
NERVE TO 
SECOND > 
LUMBRICAL ) 
EXTERNAL 
COLLATERAL ) 
TO INDEX J 
Fig. 661.—Superficial palmar nerves. (Testut) 
inner side of the thenar eminence, communicating with the musculo-cutaneous 
nerve. 
The external terminal division divides into an outer branch which crosses the 
flexor longus pollicis to the outer side of the thumb, and an inner branch Avhich 
sends collaterals to the inner side of the thumb and outer side of the index 
finger and intervening skin. 612 
THE NERVES. 
The internal terminal division splits into two branches which proceed to the 
next two finger clefts, passing under the superficial palmar arch, but superficial to 
the tendons. At the level of the metacarpo-phalangeal joints they appear 
between the divisions of the palmar fascia and split into collaterals to the con- 
tiguous sides of the index and middle, and middle and ring fingers respectively. 
Each of these nerves supplies the palmar surface of the finger to which it belongs 
and gives a dorsal twig to the nail matrix. Twigs from the digital branches supply 
the two outer lumbrical muscles, and the innermost digital branch communicates 
with the ulnar nerve. 
The small internal cutaneous nerve (Figs. 659, 666), or nerve of Wrisberg (1. th.), 
arises from the inner cord of the plexus, and descends on the inner side of the 
axillary vein, and then under the fascia, which it pierces on the inner aspect of 
the arm about the middle. It bends backward and supplies the skin over the 
olecranon and lower third of the arm. In the axilla it forms loops with the 
intercostohumeral, and sometimes also the lateral cutaneous branch of the third 
intercostal nerve. 
6. The Small Internal Cutaneous Nerve. 
7. The Internal Cutaneous Nerve. 
The internal cutaneous nerve (8 c., 1. th.) (Figs. 659, 666, 667) springs from 
the inner cord below the last. It descends in front of the axillary and brachial 
arteries, pierces the deep fascia with the basilic vein about two-thirds down the 
arm, and divides into an anterior and posterior branch. About the middle of the 
arm it gives a twig to the skin over the biceps. The anterior branch is the larger. 
It passes in front of or behind the median basilic vein, and supplies the anterior 
ulnar area of skin as low as the wrist. The 'posterior branch descends in front 
of the internal condyle, and winds sharply backward to supply the posterior ulnar 
region. 
8, The Ulnar Nerve. 
The ulnar nerve (8. c., 1. th.) (Figs. 659-667), which is the largest branch of the 
inner cord, descends between the axillary artery and vein, and along the inner 
side of the brachial artery in the upper third of the arm. It then pierces the 
internal intermuscular septum with the inferior profunda artery, and descends 
beneath the deep fascia to the interval between the internal condyle and the 
olecranon process, where it passes between the two heads of the flexor carpi 
ulnaris to run between that muscle and the flexor profundus digitorum. It joins 
the ulnar artery and lies on the inner side of that vessel in the lower two-thirds 
of the forearm, crossing the anterior annular ligament with it immediately exter- 
nal to the pisiform bone. In the palm it divides, like the artery, into a super- 
ficial and a deep division. 
Branches.—As of the median nerve the first branches of the ulnar are 
articular filaments to the elbow joint, which are given off as it passes between the 
heads of the flexor carpi ulnaris. In the forearm it supplies 'muscular branches 
(8. c., 1. th.) to the flexor carpi ulnaris and inner half of the flexor profundus 
digitorum. 
The palmar cutaneous branch is given off near the middle of the forearm. It 
descends in front of the ulnar artery, supplies twigs to that vessel, and terminates 
in the skin of the palm. 
The dorsal branch (8. c.) arises about two inches above the wrist joint, passes 
backward beneath the flexor carpi ulnaris, and is distributed to the skin on the 
dorsum of the hand, little finger, and inner side of the ring finger, communicating 
with the radial. THE CIRCUMFLEX NERVE. 
613 
The superficial terminal branch of the ulnar nerve (1. th., or 8. c. 1. th.) behaves 
similarly to the median nerve, with which it communicates; but it supplies no 
muscles. It is distributed to the little and inner side of the ring finger. 
The deep branch (8. c.) accompanies the deep branch of the ulnar artery 
M U S C U LO -SPIRAL 
RADIAL 
MUSCU LO - CUTANEOUS 
EXTERNAL BRANCH 
OF RADIAL 
—INTERNAL BRANCH 
OF RADIAL 
DORSAL BRANCH, 
OF ULNAR 
EXTERNAL BRANCH 
\ OF RADIAL 
INTERNAL DORSAL COL- 
LATERAL OF ULNAR 
PALMAR BRANCHES 
Fig. 662.—Cutaneous nerves of the dorsum of the hand. (Testut.) 
between the abductor and flexor brevis minimi digit!. It supplies all the short 
muscles of the little finger, all the interossei, the inner two lumbricals, and those 
thumb muscles, which are on the inner side of the flexor longus pollicis. 
9. The Circumflex Nerve. 
The circumflex nerve (5. 6. c.) (Figs. 658, 664, 666, 667) is one of the terminal 
divisions of the posterior cord. It turns round the lower border of the sub- 
scapularis, and accompanies the posterior circumflex artery to the back of the 
shoulder, through the quadrilateral space, bounded by the subscapularis, teres 
major, triceps, and the surgical neck of the humerus. It gives an articular 
twig to the shoulder-joint, and divides into an anterior and a posterior 
branch. 
The anterior branch winds round the humerus with the posterior circumflex 
artery, and sends many branches into the anterior part of the deltoid, some of 
which reach the skin. 
The posterior branch sends a nerve to the teres minor, which has an ovoid, 
gangliform swelling on it, and supplies the posterior part of the deltoid muscle 
and skin over the lower deltoid region. 614 
THE NERVES. 
10. The Musculo-spiral Nerve. 
The musculo-spiral nerve (6. 7. 8. c.) (Figs. 664, 659, 662, 666, 667) is the ter- 
minal and largest branch of the posterior cord. Placed at first behind the third 
part of the axillary artery and upper part of the brachial, it soon leaves the latter 
vessel, and, accompanied by the superior profunda artery, pierces the internal 
ANTERIOR 
INTEROSSEOUS 
RADI A L"T 
‘—U LNAR NERVE 
INTERNAL BRANCH/ 
OF RADIAL (if 
fBRANCH OF ANTERIOR 
j INTEROSSEOUS TO 
I WRIST JOINT 
EXTERNAL BRANCH 
OF RADIAL If 
SUPERFICIAL BRANCH 
OF ULNAR 
-DEEP BRANCH 
OF ULNAR 
-NERVE TO PALMA 
BREVIS 
DEEP BRANCH 
OF ULNAR 
TERMINATION OF 
ULNAR IN THUMB 
MUSCLES 
( NERVE TO THIRD 
"S AND FOURTH 
I LUMBRICALS 
m/ y. 
/ NERVES TO 1 
' FIRST AND 1 
SECOND 
LUMBRICALS 
] DIGITAL COL" 
r LATERAL 
) BRANCHES 
Fig. 663.—Deep palmar nerves. (Testut.) 
intermuscular septum, winds obliquely round the humerus in the spiral groove 
between the triceps and the bone, and reaching the external intermuscular septum, 
pierces it to gain the interval betAveen the brachialis anterior and brachio-radialis, 
A\diere it divides into the radial and posterior interosseous nerves. 
Before its final division it gives off an internal and an external cutaneous, and 
muscular branches to the triceps, anconeus, brachialis anterior (6. c.), brachio-radialis 
(6. c.), and extensor carpi radialis longus (6. 7. c.). Of the muscular branches those 
to the last three muscles are given off between the brachio-radialis and brachialis THE MUSCULOSPIRAL NERVE. 
615 
anterior, branches to the inner and outer heads of the triceps and anconeus arise 
while the nerve is in the spiral groove, and important branches are contributed to 
the middle and inner heads of the triceps, while the parent nerve lies behind the 
brachial artery. One of these last, called by Krause the ulnar collateral, accom- 
panies the ulnar nerve for some distance. 
The internal cutaneous branch (8. c.) arises within the axilla, and supplies a 
SUPRASCAPU-1 
LAR NERVE r 
AND ARTERY ) 
_ANTERIOH BRANCH 
OF CIRCUMFLEX 
POSTERIOR BRANCH 
OF CIRCUMFLEX 
CUTANEOUS OP 
CIRCUMFLEX 
BRANCH TO OUTER 
HEAD OF TRICEPS 
AND ANCONEUS 
.SUPERIOR PRO- 
FUNDA ARTERY 
BRANCH TO INNER 
HEAD OF TRICEPS 
EXTERNAL CUTANEOUS 
MUSCULO-SPIRAL 
ULNAR NERVE' 
Fig. 664.—Musculo-spiral and circumflex nerves of right side. (Testut.) 
strip of skin clown the inner side of the arm, between the intercosto-humeral and 
circumflex areas. 
The external cutaneous branches are two in number, the upper (6. c.) being the 
smaller. It pierces the deep fascia in the line of the intermuscular septum, and 
supplies the skin over the lower and outer part of the biceps. The lower branch 
(6. 7. 8. c.), becoming superficial a little below the last, descends behind the 
external condyle, and supplies the skin of the posterior radial region from elbow 
to wrist. 616 
THE NERVES. 
The posterior interosseous nerve (6. 7. c.) (Fig. 665), which is the terminal 
muscular branch of the nmsculo-spiral, is destined for the posterior group of 
forearm muscles. It descends between the brachialis anterior and extensor carpi 
radialis longus, where it gives branches to the extensor carpi radialis brevis and 
supinator (6. 7. c.), and then enters the substance of the latter muscle, in which 
it winds round the radius to gain the interval between the superficial and deep 
MUSCULO-SPIRAL 
BRANCH TO ANCONEUS 
NERVE TO BRACHIALIS 
TO BRACHIO- 
\? RADIALIS 
\y-N erve to extensor 
j\\cAß PI RADIALIS LONGUS 
ULNAR NERVE- 
NERVE TO EXTENSOR 
NERVE TO EXTENSOR 
CARPI ULNARIS 
NERVE TO EXTENSOR 
COMMUNIS DIGITORUM 
POSTERIOR INTEROS- 
SEOUS NERVE 
NERVE TO EXTENSOR_ 
LONGUS POLLICIS 
(NERVE TO EXTENSOR 
N OSSIS METACARPI 
( POLLICIS 
ERVE TO EXTENSOR 
BREVIS POLLICIS 
POSTERIOR CARPAL 
BRANCH OF ULNAR' 
BRANCH 
TO CARPUS 
Fig. 665,—Posterior interosseous nerve. (Testut.) 
muscles on the back of the forearm. Here it distributes twigs to all the sur- 
rounding extensors (7. c.) and passes to the interosseous membrane in the lower 
third of the forearm, where it joins the anterior interosseous artery. It descends 
beneath the posterior annular ligament under the extensor communis, and expands 
into a gangliform enlargement, from which branches are supplied to the carpal 
joints. 
The radial nerve (6. c.) (Figs. 660, 661, 662, 666, 667) is the other terminal 
division of the musculo-spiral, and is purely cutaneous in its distribution. It THE MUSCULO-SPIRAL NERVE. 
617 
descends beneath the brachio-radialis, and joins the radial artery, on whose outer 
side it runs in the middle third of the forearm. It then turns sharply backward 
beneath the brachio-radialis tendon. Piercing the deep fascia two inches above 
the styloid process of the radius, it sends a twig to the outer side of the thumb 
Fig. 666.—Cutaneous nerves of the upper limb, ventral aspect. (W. Keiller.) 
and divides into four branches, which spread fan-like over the back of the hand 
and fingers supplying the outer three and a half fingers up to, but not including, 
the terminal phalanges. It is here joined by the ulnar nerve. 618 
THE NERVES. 
Observe that the nail matrices and surrounding skin are supplied by the pal- 
mar nerves, that the little finger and inner side of the ring finger are supplied 
on both aspects by the ulnar nerve, and that the rest of the fingers are supplied 
by the median on the palmar, and by the radial on the dorsal surface. 
ULNARS 
-^MEDIAN 
Fig. 667.—Cutaneous nerves of the upper limb, dorsal aspect. (W. Keiller.) 
On the dorsum of the hand the radial and ulnar nerves overlap considerably. 
For a general view of the cutaneous nerve-supply of the arm compare 
Figures 666 and 667. THE THORACIC NERVES. 
619 
THE THORACIC NERVES. 
The thoracic nerves differ from all the other spinal nerves in that they enter 
into the formation of no plexus; but each is distributed to a transverse segment 
of the trunk, corresponding to the vertebrae from between which it emerges. 
The first thoracic nerve sends a small branch to the interval between the first 
and second ribs, the main trunk, ascending in front of the first rib to join the 
brachial plexus. Its intercostal branch behaves like the others about to be 
described, but with rare exceptions has no lateral cutaneous branch. 
The upper six thoracic nerves run round the chest wall in the spaces between 
the vertebro-sternal ribs; the remaining six pursue a transverse course through 
the abdominal wall where the ribs are deficient in front. 
A typical intercostal nerve (Fig. 668), after receiving two rami communicantes 
from the corresponding ganglion of the sympathetic, passes outward between the 
INTERNAL BRANCH 
/ (CUTANEOUS) 
EXTERNAL BRANCH 
(MUSCULAR) 
POSTERIOR 
PRIMARY DIVISIONS 
'sympathetic 
GANGLION 
RECURRENT / 
BRANCH 
“ft LATERAL 
JI CUTANEOUS 
i I BRANCH 
INTERNAL MAMMARY 
jARTERY 
Fig. 668.—Plan of a typical intercostal nerve. (W. Keiller.) 
ANTERIOR CUTANEOUS 
posterior intercostal aponeurosis and the pleura, beneath the intercostal artery. 
It enters the interval between the internal and external intercostal muscles, and 
runs in it till the external intercostal muscle becomes deficient in front. It then 
dips under the internal intercostal muscle, and, between it and the internal mam- 
mary artery and triangularis sterni, reaches the side of the sternum, where it 
pierces the chest wall to become cutaneous. 
The lower intercostals, from the seventh to the eleventli inclusive, enter the 
interval between the transversalis and internal oblique muscles, where the ribs 
are deficient in front. They run forward in the abdominal wall, enter the sheath 
of the rectus abdominis, and pierce that muscle near the middle line to supply 
the skin. 
Lateral Cutaneous Branches (Figs. 669, 670),—The first intercostal nerve has 
no lateral cutaneous branch. 620 
THE NERVES. 
The lateral cutaneous branch of the second intercostal nerve is called the inter- 
costo-humeral. It crosses the floor of the axilla just under the deep fascia, joins 
the nerve of Wrisberg, and supplies a strip of skin on the inner and posterior 
aspect of the arm. 
JNTERCOSTO- 
HUMERAL 
ANTERIOR CUTANEOUS 
NERVES OF THORAX 
ANTERIOR 
CUTA- 
NEOUS 
NERVES 
OF 
ABDOMEN 
LATERAL CUTA-'l 
NEOUS OF 111 TO ) 
XI THORACIC j 
LATERAL CUTA-'j 
NEOUS OF ILIO- > 
HYPOGASTRIC j 
ANT. CUTANEOUS 
OF X, XI, AND 
XII THORACIC 
LATERAL 
NEOUS OF XII > 
THORACIC j 
Fig. 669.—Cutaneous distribution of thoracic nerves. (Testut.) 
The lateral cutaneous branch of the third intercostal nerve has a small anterior 
branch which passes forward over the pectoralis major, and a large posterior 
branch, which, after communicating with the intercosto-humeral nerve, is dis- 
tributed to the skin of the axilla and dorsum of the scapula, a small branch 
reaching the arm. THE THORACIC NERVES. 
621 
The lateral cutaneous branches of the rest of the intercostal nerves (except the 
twelfth) pierce the superficial thoracic or abdominal muscles, in a vertical line a 
little behind the pectoral border of the axilla. Each divides into an anterior and 
a 'posterior branch for the supply of the skin over an intercostal space or corre- 
sponding area. The lateral cutaneous branches of the abdominal intercostals 
supply the external oblique muscle. 
INTER NAL 
CUTANEOUS 
INTERCOSTO 
HUMERAL 
LATERAL CUTANEOUS') 
BRANCHES OF 111 > 
TO XI THORACIC j 
LATERAL CUTA- 
NEOUS OF XII 
THORACIC 
ILIOHYPOGASTRIC 
Fig. 670—Intercostal nerves, the superficial muscles having been removed. (Testut.) 
The anterior cutaneous nerves of the thorax and abdomen are the terminations 
of the intercostals. They reach the surface close to the middle line and turn 
outward. Those of the abdomen are small and pierce the sheath of the rectus 
rather irregularly. The tenth thoracic nerve supplies the skin about the umbilicus. 
The twelfth thoracic nerve after communicating with the sympathetic and 622 
THE NERVES. 
sending a branch to join the first lumbar nerve, passes outward beneath the exter- 
nal arcuate ligament of the diaphragm and enters the abdomen. It runs along 
the lower border of the last rib, and enters the space between the transversalis 
and internal oblique, and is afterward arranged as one of the lower intercostals. Its 
lateral cutaneous branch remains undivided and is distributed to the gluteal 
region a little behind the anterior superior iliac spine. 
The muscles supplied by the intercostal nerves are the levatores costarum, 
serrati posteriores, intercostals, triangularis sterni, transversalis abdominis, exter- 
nal and internal oblique, rectus, and pyramidalis. 
THE LUMBAR NERVES. 
The anterior divisions of the five lumbar nerves increase in size from above 
downward. They communicate with the sympathetic by rami communicantes 
which reach them by running along the sides of the lumbar arteries under the 
fibrous arches from which the psoas muscle takes origin. Of these five nerves the 
upper three, with a communication from the twelfth thoracic and a considerable 
part of the fourth lumbar nerve, from the lumbar plexus, and the rest of the fourth 
lumbar nerve, with the whole of the fifth, join the sacral nerves in forming the 
sacral plexus. 
The Lumbar Plexus (Fig. 671). 
This plexus is found embedded in the substance of the psoas muscle, which 
must be removed piece by piece for its proper demonstration. 
FROM LAST THORACIC 
FIRST LUMBAR 
SECOND LUMBAR 
THIRD LUMBAR 
FOURTH LUMBAR 
TO FIFTH LUMBAR 
TO ILIACUS 
Fig. 671.—Plan of lumbar plexus. (W. Keiller.) 
A glance at the diagram will show its general constitution. From the first 
lumbar nerve spring the iliohypogastric, and ilioinguinal nerves, from the first and 
second the genitocrural, from the second and third comes the external cutaneous, 
while large sections of the second, third, and fourth nerves form the anterior 
crural, and smaller more anterior sections of the same trunks unite to form 
the obturator nerve. The accessory obturator is a small, inconstant branch derived 
from the third, and fourth nerves, and branches supply the psoas and quadratus 
lumborum from nearly all the nerves in a somewhat irregular manner. 
Regarding their relations to the psoas muscle, the iliohypogastric, ilioinguinal, 
external cutaneous, and anterior crural nerves emerge from its outer border, the 
last nerve running down its outer side to pass under the inguinal (PouparPs) THE ILIOHYPOGASTRIC NERVE. 
623 
ligament; the genitocrural nerve pierces the anterior surface of the muscle and 
descends to the pelvis in its sheath ; and the obturator and accessory obturator 
nerves and the lumbar contribution to the sacral plexus cross the pelvic brim 
along its inner side. 
1. The Iliohypogastric Nerve. 
The iliohypogastric nerve (Figs. 672, 678) rises in common with the ilioinguinal 
from the first lumbar, and occasionally blends with it to form one nerve. 
Emerging from the outer border of the psoas it crosses the quadratus in the sub- 
peritoneal areolar tissue, and enters the space between the transversalis and inter- 
TWELFTH THORACIC 
LUMBAR PORTION 
/OF SYMPATHETIC 
NERVE TO QUADRA- 
TUS LUMBORUM 
FIpST LUMBARs 
TWELFTH THORACIC 
TRANSVERSAL IS— 
OBLIQUUS INTERNUS 
OBLIQUUS EXTERNUS-T 
SECOND LUMBAR— 
—I LIO - HYPOGASTRIC 
-ILIO-INQUINAL 
I LIO-HYPOGASTRIC 
ILIAC BRANCH OF 
ILIO-HYPOGASTRIC- 
ABDOMINAL BRANCH” 
OF ILIO-HYPO. 
FOURTH LUMBAR- 
THIRD LUMBAR_ 
-GENITO-CRURAL 
-RAMUS COMMU- 
NICANS 
__EXTERNAL CUTA- 
NEOUS 
FIFTH LUMBAR— 
ILIO-INGUINAL- 
■GENITO-CRURAL 
EXTERNAL CUTANEOUI 
OBTURATOR NERVE- 
.GENITAL BRANCH 
•CRURAL BRANCH 
GENITAL BRANCH OF 
GENITO-CRURAL 
CRURAL BRANCH Of'' 
GENITO-CRURAL- 
POSTERIOR BRANCH OF" 
EXTERNAL CUTANEOUS 
ANTERIOR BRANCH OF 
EXTERNAL CUTANEOUS ~ 
APONEUROSIS OF EX- 
TERNAL OBLIQUE 
DORSAL NERVE 
OF PENIS 
Fig. 672.—Deep and superficial dissection of the lumbar plexus. (Testut.) 
nal oblique. It runs parallel with the iliac crest and, about two and a half inches 
behind the anterior superior iliac spine, gives off its iliac branch. Continuing 
onward the nerve pierces the internal oblique near the iliac spine, and becomes 
cutaneous about an inch above the external abdominal ring. 
Its iliac branch pierces the abdominal muscles and, like the corresponding 624 
THE NERVES. 
branch of the last thoracic nerve, crosses the iliac crest to the gluteal region, 
supplying the skin between the crest and the great trochanter. 
2. The Ilioinguinal Nerve. 
The ilioinguinal nerve (Figs. 672, 673, 685, 686) arises in common with the 
last and accompanies it as far as the iliac spine but a little lower, uniting with it 
in a plexiform manner. It gains the inguinal canal and appears at the external 
abdominal ring in front of the spermatic cord, dividing into branches to the 
inner side of the thigh, and the scrotum or labium majus according to sex. 
These two nerves supply twigs to the muscles of the abdominal wall. 
The genitocrural nerve (Figs. 672, 673, 677, 685, 686) arises from the first and 
second lumbar nerves. It appears on the anterior surface of the psoas muscle, 
on which it descends, dividing into two branches near the commencement of the 
external iliac artery or anywhere above this point. 
The internal or genital branch joins the external iliac artery, to which it con- 
tributes a twig, and then enters the inguinal canal. It is found on the back of 
the cord and is distributed to the cremaster muscle. In the female it is small and 
accompanies the round ligament. 
3. The Genitocrural Nerve. 
The external or crural branch accompanies the psoas under the inguinal liga- 
ment and pierces the deep fascia just outside of the common femoral artery to 
supply the skin in front of the thigh. 
4. The External Cutaneous Nerve. 
The external cutaneous nerve (Figs. 672, 673, 675, 678, 685, 686), derived from 
the second and third lumbar nerves, pierces the outer border of the psoas and 
descends across the iliacus and under the fascia iliaca to the notch beneath the 
anterior superior iliac spine. Here it enters the thigh under the inguinal ligament 
and divides into a small posterior branch to the skin in front of the great 
trochanter, and a large anterior branch which descends for some distance in a 
sheath of fascia lata, and is distributed to the skin on the outer side of the thigh 
as low as the knee, where it joins the plexus patellae. 
5. The Anterior Crural Nerve. 
The anterior crural nerve (Figs. 672, 673, 675) is the largest trunk formed by 
the lumbar plexus. It springs from the second, third, and fourth lumbar nerves, 
the roots uniting in the substance of the psoas muscle to form one trunk, which 
descends along its outer side to accompany the muscle under the inguinal 
ligament to the thigh. In the thigh the nerve is separated from the common 
femoral artery by about half an inch, and divides immediately into a large num- 
ber of branches which may conveniently be classified as cutaneous and muscular, 
some of the latter furnishing articular twigs to the hip and knee-joints. 
(a) The nerves to the iliacus are given off in the abdomen as the nerve crosses 
the muscle. 
(6) The nerve to the pectineus arises immediately below the inguinal ligament, 
and crosses outward to its muscle behind the common femoral vessels. 
(c) The nerves to the rectus and vastus externus run downward and outward 
beneath the former muscle, that to the vastus interims runs parallel with the long 
saphenous nerve as far as Hunter’s canal. Of these the nerve to the rectus sends a 
twig to the hip-joint and each of the others sends articular branches to the knee. 
(d) The middle cutaneous nerve (Figs. 673, 674, 675, 685, 686) consists of 
two strong branches, one of which pierces and supplies the sartorius. They THE ANTERIOR CRURAL NERVE. 
625 
perforate the deep fascia half way down the thigh, and supply the skin in front 
as far down as the knee-joint, joining the plexus patellae. 
(e) The internal cutaneous nerve (Figs. 675, 685, 686, 688, 690) crosses ob- 
liquely over the superficial femoral artery in Scarpa’s triangle, and divides into 
an anterior and a posterior branch, which follow the anterior and posterior borders 
of the sartorius respectively. They pierce the fascia lata in the lower third of 
the thigh and supply the skin on its inner aspect as low as the knee. The ante- 
rior branch joins the plexus patellae, and the posterior branch the subsartorial 
plexus. 
EXT. CUTANEOUS _ 
POSTERIOR BRANCH , 
OF EXT, CUTANEOUS 
ANTERIOR BRANCH _ 
OF EXT. CUTANEOUS 
ANTERIOR 
" CRURAL 
QENITO- 
"CRURAL 
MIDDLE 
‘CUTANEOUS 
BRANCH OF 
ILIOINGUINAL 
MIDDLE 
'CUTANEOUS 
CUTANEOUS BRANCH 
OF OBTURATOR 
ANTERIOR BRANCH 
OF EXT. CUTANEOUS 
INTERNAL 
‘cutaneous 
PATELLAR BRANCH 
OF LONG 
SAPHENOUS 
LONG 
SAPHENOUS 
Fig. 673.—Superficial nerves of the anterior surface of the thigh. (Testut.) 
(/) The internal or long saphenous nerve (Figs. 674, 675, 680, 683, 684, 685, 
686, 688, 690) accompanies the nerve to the vastus interims to the apex of 
Scarpa’s triangle. Here it enters Hunter’s canal, in which it descends in front 
of the femoral artery. At the lower end of the canal it seeks the surface, by 
passing with the superficial branch of the anastomotica magna artery between 
the sartorius and gracilis, and piercing the deep fascia just below the knee. It 
then joins the long saphenous vein, distributes branches to the skin all down the 626 
THE NERVES. 
inner side of the leg, and, descending in front of the internal malleolus, ends on 
the inner side of the ball of the great toe. 
Its patellar branch is given off as it leaves Hunter’s canal. It perforates the 
sartorins and supplies the skin 
on the inner side of the knee- 
joint, joining the plexus patellae. 
MIDDLE 
CUTANEOUS 
PATELLAR BRANCH 
OF INTERNAL 
L SAPHENOUS 
6. The Obturator Nerve. 
The obturator nerve (Figs. 
672, 673, 675, 677) arises from 
the second, third, and fourth lum- 
bar nerves. It descends on the 
inner side of the psoas muscle to 
the pelvic brim, and then between 
the peritoneum and pelvic fascia 
to the obturator foramen, which 
it pierces where the membrane 
is deficient, the obturator artery 
lying below it. In the obturator 
foramen it divides into an ante- 
rior and a posterior branch. 
(а) The anterior branch passes 
in front of the obturator externus 
and adductor brevis, and behind 
the pectineus and adductor longus. 
It supplies the hip-joint, the ad- 
ductor longus and brevis, the 
gracilis, and occasionally the 
pectineus, and terminates by be- 
coming cutaneous to the inner 
side of the thigh, and joining the 
subsartorial plexus. 
(б) The posterior branch 
pierces the fibres of the obturator 
externus, and descends on the 
adductor magnus and behind the 
adductor brevis. It supplies the 
hip-joint, obturator externus, and 
adductor magnus, and terminates 
in a long slender fibre, which 
enters the popliteal space on the 
inner side of or behind the femoral 
artery, and, after giving a twig 
to accompany the superior inter- 
nal articular artery, ends by 
piercing the posterior ligament 
of the knee-joint. 
..INTERNAL 
SAPHENOUS 
CUTANEOUS 
BRANCHES 
OF PERONEAL 
.LONG SAPHE- 
’ NOUS VEIN 
MUSCULO- 
CUTANEOUS 
LONG SAPHE- 
" NOUS VEIN 
ANTERIOR TIBIAL 
COLLATERAL 
BRANCHES 
TO TOES 
Fig. 674.—Superficial nerves of the front of the leg. (Tes- 
tut.) 
7. The Accessory Obturator Nerve. 
The accessory obturator nerve is a small inconstant branch, derived from the 
obturator or from the same lumbar nerves. It crosses the ascending ramus of the 
os pubis under the pectineus, and supplies that muscle and the hip-joint, forming 
a loop with the anterior branch of the obturator. 
The Plexus Patellae.—The external, middle, and internal cutaneous nerves and SACRAL AND COCCYGEAL NERVES. 
627 
patellar branch of the long saphenous interlace with each other as they supply the 
skin round the patella. 
The subsartorial plexus is formed under the sartorius, in the lower third of 
the thigh by interlacing branches of the internal cutaneous, obturator, and long 
saphenous nerves. 
EXTERNAL . 
cutaneous’ 
ANTERIOR CRURAL 
MIDDLE CU- 
TANEOUS 
INTERNAL CUTA- 
NEOUS NERVE 
NERVE TO VAS- 
TUS EXTERNUS 
NERVE TO 
RECTUS 
OBTURATOR 
NERVE 
INTERNAL SAPHE- 
NOUS NERVE 
NERVE TO VAS 
TUS INTERNUS 
SUBSARTORIAL 
PLEXUS 
PATELLAR BRANCH 
OF INTERNAL 
SAPHENOUS 
INTERNAL CUTA- 
NEOUS NERVE 
INTERNAL SAPHE- 
NOUS NERVE 
Fig. 675.—Deep nerves of the front of the thigh. (Testut.) 
THE SACRAL AND COCCYGEAL NERVES 
The anterior divisions of the upper four sacral nerves enter the pelvic cavity 
through the anterior sacral foramina, the fifth sacral nerve passes forward between 
the sacrum and cornu of the coccyx, and the coccygeal nerve leaves the spinal 
canal through its terminal opening. The upper three sacral nerves join with part 
of the fourth and the whole of the fifth lumbar nerves, and part of the fourth 628 
THE NEB VES. 
sacral nerve to form the sacral plexus; the rest of the fourth sacral and remain- 
ing nerves form the coccygeal plexus. 
The Sacral Plexus (Fig. 676). 
A variable portion of the fourth lumbar nerve joins the fifth lumbar to form 
the lumbo-sacral cord. This trunk crosses the brim of the pelvis, pierces the 
pelvic fascia, and under cover of this fascia joins the sacral nerves on the ventral 
FOURTH LUMBAR 
FIFTH LUMBAR 
VIRST SACRAL 
SECOND SACRAL 
SUPERIOR. 
GLUTEAL 
'THIRD SACRAL 
INFERIOR 
GLUTEAL 
SACRAL 
PERINEAL BR. TO SPHINCTER 
& LEVATOR ANI 
FIFTH SACRAL 
-N.TO COCCYGEUS 
viscera!? 
COCCYGEAL 
GREAT j 
SCIATIC 
Fig. 676.—Plan of sacral plexus. 
surface of the pyriformis muscle. With the first and second and greater part of 
the third sacral nerves the lumbo-sacral cord forms a great compound nervous 
trunk called the great sciatic nerve. A small band from the second sacral unites 
with the remainder of the third sacral and with the fourth sacral nerves to form 
the internal pudic nerve. Thus the two main or terminal trunks are formed; 
but, in addition to these, numerous collateral branches are given off; the superior 
gluteal, the inferior gluteal, the small sciatic, the perforating cutaneous, and 
nerves to the pyriformis, obturator interims, gemelli and quadratus feraoris. The 
branches of this plexus are divisible into a dorsal and a ventral set. In the 
diagram the dorsal set are shaded. They spring from the back of the plexus and 
supply the extensor aspect of the limb ; the ventral set spring from the anterior 
surface of the plexus and supply the flexor muscles. 
COLLATERAL BRANCHES. 
The twigs to the pyriformis are derived from the first and second sacral nerves. 
The nerve to the quadratus femoris lies on the ventral surface of the plexus, 
its fibres springing from the lumbo-sacral cord and first sacral nerve. On the 
hip it is seen descending under the obturator interims and gemelli to reach the 
ventral surface of the quadratus, distributing on its way branches to the inferior 
gemellus and hip-joint. COLLATERAL BRANCHES OF SACRAL PLEXUS. 
629 
The nerve to the obturator interims, from the fifth lumbar and upper two sacral 
nerves, appears on the hip beneath the pyriformis, crosses the spine of the ischium 
outside the internal pudic vessels, and passes through the small sacrosciatic fora- 
men to the obturator interims, supplying the superior gemellus as it passes. 
The superior gluteal nerve (Figs. 677, 679), springing from the back of the 
lumbo-sacral cord and first sacral nerve, leaves the pelvis through the great sacro- 
EXTERNAL CUTANEOUS- 
GENITO- 
CRURALS 
FIFTH 
'LUMBAR 
>tSYM PATHETIC 
TRUNK 
LUMBO-SACRAL 
CORD 
SUPERIOR 
GLUTEAL 
RAMUS 
COMMUNICANS 
GENITAL BRANCH OF- 
GEN ITO-CRURAL 
CRURAL BRANCH OF 
GENITO-CRURAL 
VISCERAL 
z BRANCHES 
NERVE TO 
"LEVATOR ANI 
HEMORRHOIDAL BRANCH 
OF PUDIC 
SMALL SCIATIC 
'INTERNAL pudic 
EXTERNAL SUPER- 
FICIAL PERINEAL 
■INTERNAL SUPER- 
FICIAL PERINEAL 
LEFT DORSAL- 
DORSAL 
OF PENIS 
NERVE TO BULB 
'LONG PUDENDAL 
Fig. 677.—Sacral plexus of the right side. (Testut.) 
sciatic foramen with the gluteal vessels, and under the gluteus medius divides 
into a small superior branch to that muscle, and a larger inferior branch, which 
accompanies the inferior branch of the gluteal artery and is distributed to the 
gluteus medius and minimus, and tensor vaginae femoris. 
The inferior gluteal nerve (Fig. 679) arises from the lumbo-sacral cord and 
first and second sacral nerves, and is frequently closely associated with the small 
sciatic nerve. It emerges from the great sacrosciatic foramen beneath the pyri- 
formis, and enters the deep surface of the gluteus maximus, which it supplies. 
The small sciatic nerve (ischiatic nerve) (Figs. 677, 678, 679, 687, 688) is a 
purely cutaneous nerve, supplying the skin of the buttock, perineum, and back 
of the thigh and popliteal region. It springs from the back of the upper three 
sacral nerves, and appears on the buttock beneath the pyriformis, and on the sur- 
face of the great sciatic nerve. At the lower border of the gluteus maximus it 
lies under the deep fascia on the middle line of the back of the thigh. Distrib * 
uting cutaneous filaments as it descends, its terminal fibres pierce the deep fascia 630 
THE NERVES. 
at the bend of the knee, and end in the skin of the calf, joining the external 
saphenous nerve. Its cutaneous branches to the gluteal region are two or three in 
number, and bend upward over the lower border of that muscle to the skin of 
the lower and outer part of the buttock. 
Its inferior pudendal branch turns inward beneath the tuber ischii and pierces 
ILIAC BRANCH OF 
ILIO-H YPOGASTRIC 
fLATERAL CUTANEOUS 
BRANCH OF TWELFTH 
[thoracic 
POSTERIOR 
DIVISION 
OF LUMBAR 
POSTERIOR 
BRANCH OF 
EXTERNAL 
CUTANEOUS 
POSTERIOR 
OF SACRAL 
DIVISION 
LONG PUDENDAL, 
GLUTEAL CUTANEOUS 
BRANCH OF SMALL- 
ANTERIOR BRANCH 
OF EXTERNAL CU- 
TANEOUS 
SCIATIC 
SMALL ,w 
SCIATIC 
_ SMALL 
SCIATIC 
SMALL 
SCIATIC' 
SMALL 
SCIATIC 
SMALL 
SCIATIC 
EXTERNAL SAPHENOUS VEIN 
(under deep fascia) 
Fig. 678.—Superficial nerves of buttock and back of thigh. (Testut.) 
the fascia lata on the inner side of the thigh about one inch in front of the tuber- 
osity. It supplies the skin in this region, and passes forward and inward to the 
scrotum or labium majus, joining the external superficial perineal branch of the 
internal pudic nerve. 
The perforating cutaneous nerve is a small twig from the second and third THE GREAT SCIATIC NERVE 
631 
sacral nerves, which pierces the great sacrosciatic ligament to reach the skin over 
the lower and inner part of the gluteus maximus. 
The Pudic Nerve (Figs. 677, 679). 
TERMINAL BRANCHES. 
The greater part of the third sacral nerve is augmented by contributions from 
the second and fourth to form the pudic trunk, which emerges from the pelvis 
through the great sacrosciatic foramen, hooks round the small sacrosciatic liga- 
ment on the inner side of the pudic vessels, and enters the outer wall of the 
ischiorectal fossa, where it accompanies the vessels just mentioned. At the back 
of the fossa it gives off its inferior hemorrhoidal branch, and about one inch 
farther forward divides into the perineal nerve and the dorsal nerve of the 
penis. 
The Inferior Hemorrhoidal Nerve pierces the obturator fascia well back under 
cover of the gluteus maximus, and crosses inward through the fat of the ischio- 
rectal fossa, distributing its branches in fan-like manner to the sphincter ani 
externus and the skin round the anus. 
The perineal nerve consists of a superficial and a deep division. The super- 
ficial division forms two nerves. The posterior or external superficial perineal nerve 
crosses the transverse perinei superficially, and runs forward in the scrotum or 
labium majus outside the superficial perineal vessels. It interlaces with the long 
pudendal and internal superficial perineal nerve. The anterior or internal superficial 
perineal nerve enters the ischiorectal fossa in front of the preceding, pierces the 
transversus perinei muscle, and passes forward on the inner side of tbe superficial 
perineal vessels to the scrotum or labium majus, interlacing with the nerve pre- 
ceding. The deep division crosses inward parallel with the transversus perinei, 
and distributes branches to the external sphincter, levator ani, transversus perinei, 
ischio-cavernosus, and bulbo-cavernosus, and to the corpus spongiosum and ure- 
thral mucous membrane. 
The dorsal nerve of the penis passes with the internal pudic vessels between 
the layers of the triangular ligament. Here it sends twigs to the constrictor 
urethrae and corpus cavernosum, and then pierces the inferior layer of the tri- 
angular ligament, appearing on the dorsum of the penis on the outer side of the 
dorsal vessels. It is distributed to the skin covering the corpus cavernosum and 
glans, communicating with sympathetic fibres. 
In the female a similar but much smaller nerve is distributed to the clitoris. 
The Great Sciatic Nerve. 
The great sciatic nerve (Figs. 679, 681) is a compound trunk consisting of 
two great divisions—the peroneal (external popliteal) and the popliteal (internal 
popliteal). With the latter are associated the nerves which supply the hamstrings 
and adductor magnus. These are usually united to form one great trunk, which 
divides into popliteal and peroneal a little below the middle of the thigh; but 
they may be actually separate, or easily separated by dissection, as far as their 
constituent elements in the sacral plexus. Thus analyzed, the popliteal segment 
is seen to consist of ventral portions of the lumbosacral cord and upper three 
sacral nerves, and the peroneal nerve is traceable to the dorsal surface of the 
lumbosacral cord and upper two sacral nerves. 
The great sciatic nerve appears on the buttock at the lower border of 
the pyriformis, crosses the gemelli, obturator internus, and quadratus femoris 
under cover of the gluteus maximus. At the lower border of the last muscle it 
is found midway between the tuber ischii and the great trochanter in an angle 
formed by the gluteus maximus and biceps. It now descends on the adductor 632 
THE NER VES. 
Magnus, and is crossed obliquely by the long head of the biceps, dividing at a 
variable distance down the thigh into the (internal) popliteal and peroneal nerves. 
GLUTEAL NERVE 
SUPERIOR 
INTERNAL PUDIC 
NERVE 
‘GLUTEAL NERVE 
INFERIOR 
LONG PUDEN-_ 
DAL NERVE 
INTERNAL POP- 
-1 LITEAL NERVE 
EXTERNAL POP 
LITEAL NERVE 
RAMUS COMMUNI- 
CANS PERONEI 
RAMUS COMMUNI- 
CANS POPLITEI 
CUTANEOUS BRANCH 
OF EXTERNAL POP 
LITEAL 
Fig. 679.—Deep nerves of buttock and back of thigh. (Testut.) 
It gives off four branches, viz., one to the semitendinosus, one to the semimem- 
branosus and adductor magnus, and one to each head of the biceps. 
The Internal Popliteal Nerve (Figs, 679, 680, 681). 
The internal popliteal (nervus tibialis) descends vertically down the middle 
of the popliteal space, till, reaching the lower border of the popliteus muscle, it 
is named the posterior tihial nerve. At first some distance on the outer side of POSTERIOR TIBIAE NERVE. 
633 
the popliteal vessels, where these vessels reacli the middle line, it is closely 
adherent to the posterior surface of the vein, tending toward the inner side 
below. 
Branches.—The articular branches, usually three in number, accompany the 
superior and inferior internal 
articular, and azygos articu- 
lar arteries to the knee-joint. 
The upper is frequently 
absent. 
■INTERNAL POPLITEAL 
.EXTERNAL POPLITEAL 
MUSCULAR TO GAS- 
The muscular branches 
are distributed to the gastroc- 
nemius (1. 2. s.), plantaris 
(4. 5. 1, 1. s.), soleus (5. 1, 1. 
2. s.), and popliteus (4. 5. 1, 
1. s.). Of these the nerve 
to the popliteus is given off 
MUSCULAR TO 
GASTROCNEMIUS" 
TROCNEMIUS 
INTERNA! 
SAPHENOUS 
RAMUS COMMUNI 
CANS TIBIALIS 
RAMUS COMMUIMI- 
CANS FIBULARIS 
under the gastrocnemius and 
descends on the outer side of 
the popliteal vessels to reach 
the lower border of its mus- 
cle. It winds beneath it and 
supplies the muscle on its 
RAMUS COMMUIMI- 
- FIBULARIS 
internal 
saphenous 
anterior surface, giving also 
a branch to the tibia accom- 
panying its medullary artery, 
one to the interosseous mem- 
brane and inferior tibiofibular 
joint, and another to the 
superior tibiofibular articula- 
.RAMUS COMMUNI- 
CANS FI BU LA RIS 
INTERNAL 
SAPHENOUS 
tion. 
The cutaneous branch 
(ramus communicans tibialis 
vel poplitei) descends along 
the middle of the leg in the 
groove between the heads of 
the gastrocnemius, and pierces 
the deep fascia about half 
way down, to be joined by a 
similar branch from the pe- 
roneal nerve (ramus com- 
raunicans peronei). Together 
PLANTAR CUTANEOUS 
BRANCH OF POS- 
TERIOR TIBIAL 
they form the short or exter- 
nal saphenous nerve, which 
Fig. 680.—Superficial nerves of the hack of the leg. (Testut.) 
now accompanies the short saphenous vein beneath the external malleolus to the 
outer side of the foot, where it supplies the outer side of the foot and little toe, 
communicating with the musculocutaneous. It distributes branches to the skin 
on the back of the leg, external calcanean branches to the outer side of the heel, 
and articular branches to the ankle and astragalo-calcanean joints. 
Posterior Tibial Nerve (Fig. 681). 
At the lower border of the popliteus muscle the popliteal nerve is called the 
posterior tibial. It passes down the middle of the leg on the deep muscles, and 
beneath the deep transverse sheet of fascia. The posterior tibial artery is at first 
on the onter side of the nerve, but, after giving off the peroneal artery, it crosses 
abruptly a little inward beneath the nerve, and then descends on its inner side. 634 
THE NERVES. 
Between the internal malleolus and the inner tuberosity of the os calcis the 
posterior tibial divides into the internal and external plantar nerves. 
Branches.—(a) Muscular branches (5. 1., 1. 2. s.) supply the tibialis posterior, 
flexor longus digitorum, and flexor longus hallucis; besides which there is a sup- 
plementary branch to the soleus. 
(b) The fibular branch accompanies the peroneal artery, supplying these vessels, 
the fibular periosteum and the medulla of that bone. 
GREAT SCIATIC 
NERVE 
NERVE TO GASTROCNEMIUS' 
PERONEAL 
NERVE 
RAMUS COM MU NICANS-* 
TIBIALIS 
POPLITEAL. 
ARTERY 
I NTERNAL 
POPLITEAL 
NERVE 
NERVE TO_ 
POPLITEUS 
RAMUS COMMU- 
NICANS FIBU- 
LA RIS 
NERVES TO, 
SOLEUS 
CUTANEOUS BRANCH 
OF PERONEAL 
POSTERIOR TIBIAL 
ARTERY 
NERVES TO SOLEUS 
PERONEAL ARTERY 
POSTERIOR TIBIAL_ 
NERVE 
NERVE TO 
TIBIALIS 
.POSTICUS 
NERVE TO FLEXOR 
LONGUS DIGI - 
TORUM 
NERVE TO 
FLEXOR LON- 
GUS HALLUCIS 
POSTERIOR TIB-. 
IA L ARTERY 
PLANTAR CUTA- 
NEOUS NERVE 
Fig. 681.—Deep nerves of the back of the leg. (Testut.) 
(c) The calcaneo-plantar nerve (1. 2. s.), arising from the posterior tibial in the 
lower fourth of the leg, becomes cutaneous by piercing the internal annular liga- 
ment. It then divides into internal calcaneal branches to the skin of the heel, 
and plantar cutaneous branches to the inner side of the sole. 
(d) Articular filaments supply the ankle-joint. 
The Internal Plantar Nerve (Figs. 682, 684, 686, 689, 690) (4. 5. 1., 1. s.) is 
slightly the larger of the two terminal divisions of the posterior tibial. It dis- 
tributes cutaneous nerves to the inner three and a half toes, and supplies the POSTERIOR TIBIAE NERVE. 
635 
abductor hallucis, flexor brevis digitorum, flexor brevis hallucis, and inner 
lumbrical muscle. It passes forward under the origin of the abductor hallucis, 
then in the groove between that muscle and the flexor brevis digitorum, accom- 
panying the internal plantar artery. Under cover of the plantar fascia it divides 
into four digital nerves. Of these the innermost passes undivided to the inner 
side of the great toe, giving a branch on its way to the flexor brevis hallucis, the 
remaining three nerves, emerging between the processes of plantar fascia, divide 
each into two collateral branches for the adjacent sides of the corresponding toes, 
the digital nerve to the first cleft supplying the inner lumbrical muscle, and the 
most externa] branch communicating with the external plantar nerve. The 
muscular branches to the abductor hallucis and flexor brevis digitorum are given 
POSTERIOR TIB- 
INTERNAL PLANTAR 
IA L NERVE 
_ NERVE TO 
ACCESSORIUS 
NERVE 
NERVE TO AC- 
CESSORIUS 
NERVE TO ABDUC 
NERVE TO FLEXOR 
BREVIS DIGITORUM 
TOR HALLUCIS 
EXTERNAL 
PLANTAR 
NERVE TO AB- 
DUCTOR HAL- 
LUCIS 
COMMUNICATING 
TO INTERNAL 
, PLANTAR 
CUTANEOUS TO THREE 
AND A HALF INNER TOES 
NERVE TO FLEXOR 
BREVIS HALLUCIS 
NERVES TO 
TWO INNER 
LUM BRICALS 
Fig. 682.—Plantar nerves. (Testut.) 
off near the commencement of the nerve, articular fibres supply some of the 
joints of the foot, and plantar cutaneous twigs are distributed to the sole. As in 
the case of the corresponding nerve of the hand, the plantar digital nerves supply 
the skin on the dorsum of the ungual phalanx and the bed of the nail. 
The External Plantar Nerve (Figs. 682, 684, 689, 690) accompanies the exter- 
nal plantar artery between the flexor brevis digitorum and flexor accessorius, till, 
gaining the hollow between the former muscle and the abductor minimi digit!, it 
divides into a superficial and a deep branch. Before dividing, it gives branches 
to the flexor accessorius and abductor minimi digit!. 
The superficial terminal branch sends one digital branch to the outer side of the 
little toe, and a second, which, passing beneath the plantar fascia to the cleft 
between the fourth and fifth toes, divides into collateral branches to their adjacent 
surfaces, first communicating with the internal plantar nerve. The outer digital 636 
THE NEB VES. 
branch supplies a twig to the flexor brevis minimi digit!, and occasionally sup- 
plies the interosseous muscles of the fourth space. 
The deep branch of the external plantar nerve continues to accompany the 
external plantar artery beneath the long flexor tendons. It supplies branches to 
all the interosseous muscles (except occasionally those of the fourth space), the 
outer three lumbricals, and the adductor obliquus and adductor transversus bal- 
lads ; as well as articular filaments to the tarso-metatarsal and metatarso-phal- 
angeal joints. 
External Popliteal or Pero- 
neal Nerve (4. 5.1; 3. 2. s.). 
PATELLAR BRANCH OF 
INTERNAL SAPHE- 
This nerve (Figs. 674, 679, 
680, 681, 683, 686, 688) de- 
scends obliquely along the 
outer boundary of the pop- 
liteal space following closely 
the inner border of the biceps 
muscle and its tendon as far as 
the fibula, thus crossing the 
outer head of the gastrocne- 
mius. Beneath the head of the 
fibula it winds round the outer 
side of that bone, piercing the 
peroneus longus, and in its 
substance dividing into the 
musculocutaneous and anterior 
tibial nerves. Shortly after 
its formation it gives off, fre- 
quently by one common trunk, 
two external articular branches, 
which accompany the superior 
and inferior external articular 
arteries to the knee-joint. A 
recurrent articular branch is 
given off just before the nerve 
bifurcates. It passes under the 
peroneus longus and extensor 
longus digitorum to join the 
anterior tibial recurrent artery. 
Many of its fibres end in the 
upper end of the tibialis an- 
terior, but some pass to the 
superior tibio-fibular joint, the 
periosteum over the outer tu- 
berosity of the tibia and the 
knee joint. 
Of the twro cutaneous 
NOUS NERVE 
EXTERNAL POP 
LITEAL NERVE 
MUSCULO-CUTA 
NEOUS NERVE 
INTERNAL SAPHE 
NOUS NERVE 
ANTERIOR 
TIBIAL NERVE 
CUTANEOUS BRANCH) 
OF MUSCULO- 
CUTANEOUS 
.EXTERNAL BRANCH OF 
ANTERIOR TIBIAL 
INTERNAL BRANCH OF 
ANTERIOR TIBIAL 
‘EXTENSOR BREVIS 
DIQITORUM 
EXTERNAL 
SAPHENOUS' 
branches (5. 1., 1. 2. s.) the 
ramus communicans peronei or 
fibular communicating branch 
joins the tibial, communicating 
below the middle of the leg 
to form the short saphenous 
nerve. Sometimes they do not 
join, and then this nerve usually 
MUSOULO-OUTANEOUS 
BRANCHES OF 
Fig. 683.—Deep nerves of the front of the leg. (Testut.) 
ends on the heel or outer side of the foot. The lateral cutaneous branch of the pero- 
neal nerve supplies the skin along the outer side of the upper two thirds of the leg. EXTERNAL POPLITEAL OR PERONEAL NERVE. 
637 
The Musculocutaneous Nerve (4. 5. 1., 1. s.) (Figs. 674, 683, 684, 685, 686) 
descends obliquely beneath the peronei muscles, and between them and the exten- 
sor longus digitorum, supplies muscular branches to the peroneus longus and brevis, 
and pierces the deep fascia near the middle line of the leg near its lower fourth. 
It then divides into two branches, internal and external, which descend in the 
superficial fascia to the dorsum of the foot, supplying filaments to the skin on the 
front of the leg, as they proceed downward. 
The internal branch sends a branch to the inner side of the great toe, com- 
municating with the long saphenous nerve, a second branch to join the anterior 
tibial nerve as it divides into collaterals to the contiguous side of the first and 
second toes, and a third branch to supply collaterals to the second and third toes. 
The external branch supplies 
digital nerves to the contiguous 
sides of the third and fourth, and 
fourth and fifth toes, and com- 
municates with the short saphe- 
nous nerve. 
INTERNAL BRANCH 
OF MUSCULO- 
CUTANEOUS 
ANTERIOR 
tibiall 
INTERNAL SAPHE- 
I NOUS VEIN 
EXTERNAL BRANCH 
OF MUSCULO- \ 
CUTANEQUS||||[I 
INTERNAL 
SAPHENOUS 
NERVE 
It will thus be seen that the 
short saphenous nerve supplies 
the outer side of the little toe, 
the anterior tibial supplies the 
contiguous surfaces of the first 
and second toes, and the mus- 
culocutaneous nerve supplies 
all the rest of the dorsum of 
the foot; the long saphenous 
nerve stopping short at the ball 
of the great toe. 
The Anterior Tibial Nerve (4. 
5. 1., 1. s.) (Figs. 674, 683, 684, 
685, 686) descends obliquely 
through the peroneus longus and 
extensor longus digitorum to lie 
on the interosseous membrane 
and anterior tibial artery. It 
reaches the side of that vessel 
about the junction of the upper 
and second fourths, descends a 
short distance on its outer side, 
and then in front of it, to be 
again placed on the outer side 
(occasionally inner side) of the 
vessel beneath the anterior an- 
nular ligament. Here it divides 
into an internal and an external 
branch. 
EXTERNAL BRANCH 
OF ANTERIOR 
TIBIAL 
EXTERNAL, 
SAPHENOUS 
ANTERIOR 
TIBIAL 
BRANCHES OF 
EXTERNAL PLAN- 
TAR NERVE 
BRANCHES OF INTERNAL 
PLANTAR NERVE 
Fig. 684.—Nerves of the dorsum of the foot. (Testut.) 
Branches.—(a) Muscular branches supply the tibialis anterior, extensor 
longus digitorum, extensor proprius hallucis, and peroneus tertius. 
(5) An articular filament supplies the ankle-joint. 
(c) The external branch crosses outward under the extensor brevis digitorum, 
becomes enlarged like the posterior interosseous in the hand, and breaks up into 
branches, which supply the extensor brevis digitorum and the tarsal joints. 
{d) The internal branch appears to be the direct continuation of the nerve, 
as it accompanies the dorsalis pedis artery, lying usually on its outer, sometimes 
on its inner side. Opposite the tarso-metatarsal joint it communicates with the 
musculo-cutaneous, and divides into branches to the outer side of the great, and 
inner side of the second, toe. 638 
THE NERVES. 
Fourth and Fifth Sacral and the Coccygeal Nerves. 
The Fourth Sacral Nerve.—As already described, a small portion of the fourth 
sacral nerve ascends to join the sacral plexus. The remainder divides into vis- 
ceral and muscular branches and a communicating filament to the fifth sacral. 
The visceral branches descend on the pelvic surface of the coccygeus and levator 
I LIO HYPO GASTRIC 
XII THORACIC 
EXTERNAL 
saphenous” 
INTERNAL 
CALCANEAN 
EXTERNAL SAPHENOUS I. 11. S.- 
external 
PLANTAR " 
INTERNAL 
PLANTAR ' 
ANTERIOR TIBIAL IV. V. L. I. S 
EXTERNAL PLANTAR- 
INTERNAL PLANTAR IV. V. L.- 
of the lower limb. (W. Keiller.) 
Fig. 685.—Cutaneous nerves of the front 
the front of the lower limb. (W. Keiller, after Testut.) 
Fig. 686.—Areas of distribution of cutaneous nerves of 
ani to the bladder, rectum, and, in the female, the uterus and vagina. They com- 
municate freely with the pelvic sympathetic and visceral branches of the third 
sacral nerve. 
The muscular branches supply the levator ani and coccygeus on their pelvic 
surface, and a twig to the external sphincter (perineal branch) pierces the coccy- THE SYMPATHETIC NERVES. 
639 
gens or passes between it and the levator ani to the postero-internal angle of the 
ischio-rectal fossa, thus reaching its muscle and supplying it and the skin around 
the anus. 
The Fifth Sacral Nerve, emerging from the spinal canal between the sacrum 
and cornu of the coccyx, enters the pelvis, and on the pelvic surface of the 
coccygeus muscles gives an ascending filament to join the fourth sacral, a descend- 
ing filament to unite with the coccygeal nerve. It then descends on the coccygeus 
toward the tip of the coccyx, supplies twigs to the coccygeus muscle, and finally 
pierces that muscle to end in the skin over the coccyx. 
The Coccygeal Nerve is an exceedingly small filament, which emerges from the 
lower end of the spinal canal, and pierces the sacrosciatic ligaments and coccygeus 
muscle to join the fifth sacral nerve. 
The connection between the fourth and fifth sacral and coccygeal nerves is 
called the coccygeal plexus. 
THE SYMPATHETIC NERVES. 
The sympathetic system consists of two chains of ganglia, lying one on each 
side of the spinal column, which are developed as outgrowths from the spinal 
cord, and remain permanently connected with the spinal nerves. Its function is 
to innervate the viscera, glands, heart and blood-vessels, and the unstriped mus- 
cles of the body generally. This system presides in fact over the vital or vegeta- 
tive, as contrasted with the voluntary or exclusively animal functions of the 
body, remaining, however, under control of the central nervous system. 
If we take the arrangement in the thorax as typical, the ganglia should cor- 
respond in number with the spinal nerves; but in the neck there are only three 
ganglia, several being fused into one, and in the abdomen also the number is 
short; so that, while there are 31 spinal nerves on each side, there are only 20 to 
23 ganglia. Each ganglion is reddish-gray in color, somewhat fusiform in shape 
and softish in consistence, but enclosed in a strong fibrous sheath. It is connected 
with that above and below it by an ascending and a descending trunk, and with at 
least one spinal nerve by one or two rami communicantes. Each ganglion dis- 
tributes rami eferentes, which either directly or through the intervention of a 
secondary plexus supply blood-vessels or viscera, the efferent branches to the limbs 
and body-wall, however, joining the spinal nerves by the gray rami communicantes, 
and thus reaching their destination. 
The gangliated cords are connected superiorly with the upper cranial nerves 
by branches which enter the cranium with the internal carotid artery, and infe- 
riorly they converge over the front of the sacrum to meet in a single ganglion in 
front of the coccyx. 
In addition to these two chains the following also belong to the sympathetic 
system : 
1. Sporadic ganglia, namely the ciliary, Meckel’s, otic, and submandibular, 
connected with cranial nerves and described with them. 
2. The great prevertebral plexuses, consisting of aggregations of nerves and 
ganglia, which are connected with the gangliated cords and cerebro-spinal nerves 
on both sides of the body, and meet in front of the vertebral axis. These are, the 
cardiac plexus, lying above the heart and supplying it; the solar plexus, situated 
in the abdomen behind the stomach, and supplying most of the abdominal viscera 
and their vessels ; and the hypogastric plexus, which is placed between the two 
common iliac arteries, and supplies the pelvic viscera. 
3. Secondary Plexuses.—Many of the viscera possess minute secondary 
gangliated plexuses of their own, the ganglia being often microscopic in size; 
e.g., the heart, suprarenal bodies, uterus, and intestines. 
The ganglia of the sympathetic cords (vertebral ganglia) (Fig. 691) consist 
of nerve-cells, and medullated and non-meclullated nerve-fibres. The medullated 640 
THE NERVES. 
nerve-fibres are derived probably wholly from the motor roots of spinal or cranial 
nerves, and form the white rami communicantes. They terminate in arboriza- 
tions round the cells of the vertebral ganglia, or pass through these without 
interruption to enter into relationship with the cells of the prevertebral plexuses. 
I LIOHYPOGASTRIC 
LUMBAR 
XII THORACIC 
DORSAL DIVI 
SIGNS OF 
SACRAL 
NERVES 
SACRAL- 
PERFORATING 
CUTANEOUS 
OF FOURTH 
PERFORATING OF 
FOURTH SACRAL 
SACRAL 
INTERNAL 
CUTANEOUS 
LATERAL 
CUTANEOUS 
OF PERONEAL 
INTERNAL 
SAPHENOUS 
MUSCULOCUTANEOUS 
/ IV. V. L. I. S. 
MUSCULOCUTANEOUS 
INTERNAL . 
CALCANEAN 
INTERNAL 
CALCANEAN 
I. 11. S. 
Fig. 687.—Cutaneous nerves of the back of the 
lower limb. (W. Keiller.) 
Fig. 688.—Areas of distribution of the cutaneous 
nerves of the back of the lower limb. (Testut.; 
Medullated nerves (forming white rami communicantes) are not furnished to the 
sympathetic cords by all the cerebro-spinal nerves. In man white rami com- 
municantes are derived from the thoracic and the first (and perhaps the second) lum- 
bar nerves ; while the short root of the ciliary ganglion from the third nerve, the 
visceral branches of the facial, glossopharyngeal, vagus, and spinal accessory, and THE SYMPATHETIC NERVES. 
641 
the visceral branches of the second, third, and fourth sacral nerves may be classed 
in the same category, though most of these join the subsidiary plexuses and not 
the gangliated cords 
Fig. 689.—Cutaneous nerves of the sole. (W. Keif 
ler.) 
Fig. 690.—Areas of distribution of the cutaneous 
nerves of the sole. (W. Keiller.) 
The non-medullated nerves commence as axis-cylinder processes of the gan- 
glion cells. Some are distributed in gray rami communicantes to spinal nerves, 
and in them reach the vessels, fasciae, bones, etc., for which they are destined ; 
ACCOMPANYING DORSAL 
ROOT TO DURA DORSAL SPINAL 
NERVE ROOT 
TO VERTEBRAE LIGAMENTS, 
" SPINAL VESSELS & DURA 
HIGHER GANGLIA 
SOMATIC VASOMOTOR, 
PILOMOTOR, SECRETORY 
[SYMPATHETIC TRUNK 
7RAMI EFFERENTES 
-SYMPATHETIC GANGLION 
FROM RAMUS'COMMUN. 
TO VERTEBRA AND 
INTERCOSTAL AND 
LUMBAR VESSELS. 
MEDULLATED FIBRES PASSING THROUGH THE 
GANGLION TO PREVERTEBRAL PLEXUSES 
OR DIRECTLY TO VISCERA. 
[GRAY VISCERAL FIBRES 
'.SYMPATHETIC TRUNK 
TFROM LOWER GANGLIA 
'TO LOWER GANGLIA 
r„,TIG- f,91-Trlan of a vertebral ganglion of the sympathetic cord and its connections. Medullated fibres 
lepresenteu by continuous lines, non-medullated fibres by interrupted lines. For references to letters see 
text. (W. Keiller.) 
some join neighboring ganglia, and others pass in rami efferentes directly to 
viscera and vessels or to the prevertebral plexuses. 642 
THE NERVES. 
These connections will be better understood by examining the plan drawn out 
in Fig. 691. There a represents a medullated nerve-fibre from a ventral nerve- 
root, passing by a Avhite ramus communicans through the ganglion directly con- 
nected with that spinal nerve to a ganglion higher up, where it will form an 
arborization round a nerve-cell, like e ; 6, a medullated nerve-fibre forming an 
arborization round a cell of the ganglion of its own segment; c, a fibre passing 
through the ganglion without interruption and leaving it by one of its efferent 
branches to a prevertebral plexus or directly to some viscus; d, a fibre passing 
through the ganglion to some lower ganglion, there to end round some nerve-cell, 
or pass out through an efferent ramus ; e, a medullated nerve from a lower gan- 
glion, behaving as a. 
The dotted lines are non-medullated nerves. The fibre,/, arises as the axis- 
cylinder process of a ganglion cell, and passes by a gray ramus communicans 
along the sheath of the posterior nerve-root to the spinal meninges; g passes by 
the posterior division to supply sympathetic fibres to its area of distribution ; h 
enters the anterior division and is similarly distributed; k joins the spinal recur- 
rent branch to supply the interior of the vertebral canal, and I passes for a little 
way along the gray ramus communicans, but leaves it to be distributed to the 
sides of the vertebree and intercostal or lumbar vessels. Gray fibres to the pre- 
vertebral plexuses, vessels, or viscera, are represented by m, m; and n, n are non- 
medullated fibres joining neigh- 
boring ganglia. In addition 
to these, sensory fibres from 
the ganglia of the posterior 
CAVERNOUS PLEXUS 
SUP. MAXILLARY NERVE 
PALATINE 
GANGLION 
spinal nerve-roots pass through 
the sympathetic ganglia to vis- 
cera without interruption. 
CAROTID PLEXUS 
FIRST 
CERVICAL 
The Sympathetic in the 
Neck. 
NERVE 
s UPPER CERVICAL 
GANGLION 
In the neck there are only 
three ganglia (Fig. 692). The 
upper one, however, is an inch 
or more in length, and is fre- 
quently constricted at intervals. 
It is connected with the four 
upper cervical nerves and ap- 
pears to consist of four ganglia 
fused together. 
The second ganglion is 
small, but is connected with 
two nerves; and the third 
ganglion, intermediate in size, 
is connected with the lower 
two cervical nerves. These 
ganglia and their intervening 
cord lie in front of the trans- 
verse processes of the cervical 
vertebrae, being separated from 
them by the rectus capitis an- 
terior major above and longus 
.MIDDLE CERVICAL 
. GANGLION 
EIGHTH 
=* LOWER CERVICAL 
k GANGLION 
CERVICAL 
NERVE 
THORACIC 
NERVE 
Fig. 692.—Diagram of the cervical sympathetic. (Testut.) 
Colli below with the preA erte- 
bral fascia. The common and 
internal carotid arteries and the carotid sheath lie in front of them, and the vagus 
nerve lies to the outer side. 
The Superior Cervical Ganglion.—This ganglion is fusiform in shape, reddish- THE SYMPATHETIC NERVES. 
643 
gray in color, an inch to an inch and a half long, and is placed in front of the 
transverse processes of the second and third cervical vertebrae, and rectus capitis 
anterior major. In front of it is the internal carotid artery, and to its outer side 
the vagus nerve. 
Connections.—Its ascending branch enters the cranium; its lower end is con- 
nected to the second ganglion. Gray rami communicantes pass from it to the four 
upper cervical nerves, while its medullated connections with the spinal cord take 
a circuitous course, being derived from the upper dorsal nerves, and ascending to 
join it through the sympathetic trunk. 
Besides connections with cranial nerves, through its ascending branch (about to 
be described), it is joined by filaments to the lower ganglion of the vagus and 
the hypoglossal nerve ; and a small jugular branch ascends to the jugular fora- 
men, and there divides into two, one branch going to the root ganglion of the 
pneumogastric, and the other to the petrosal ganglion of the glossopharyngeal. 
It distributes pharyngeal branches to the pharyngeal plexus, filaments to the 
upper cervical vertebrae and their ligaments, and branches to blood-vessels ; and 
from it also springs the upper cardiac nerve. 
The Ascending Branch.—The ascending or carotid branch runs upward on the 
inner side of the carotid artery to the carotid canal where it divides into an inner 
and an outer division. Each division gives off some special branches, and then 
they both ascend on the termination of the carotid artery, supply that vessel, and 
terminate in plexuses on the ophthalmic and anterior and middle cerebral arteries. 
The outer division, as it ascends on the outer side of the carotid trunk, receives 
one or two carotico-tympanic filaments from the tympanic branch of the glosso- 
pharyngeal, and then forms the carotid plexus on the carotid artery, as it lies in 
the carotid canal. This plexus gives a twig to the sixth nerve as the latter crosses 
the carotid artery, some filaments to the Gasserian ganglion, the large deep petrosal 
nerve to the Vidian, and the small deep petrosal nerve to the tympanic plexus. 
The inner division ascends on the inner side of the carotid artery, and forms 
a plexus on that vessel as it lies in the wall of the cavernous sinus, which is 
hence called the cavernous plexus. From this plexus filaments are given to the 
third nerve near its bifurcation, and to the1 fourth nerve as it runs in the outer wall 
of the cavernous sinus. The sympathetic root of the ciliary ganglion and filaments 
to the pituitary body are also derived from this plexus. 
The pharyngeal branches of the sympathetic arise from the fore part of the 
ganglion. They descend on the side of the pharynx and unite with the pharyn- 
geal branches of the pneumogastric and glossopharyngeal to form the pharyngeal 
plexus. 
The superior cardiac branch of the sympathetic springs by two or more 
branches from the ganglion and sometimes from the sympathetic trunk below it. 
It descends behind the carotid sheath on the longus colli muscle and prevertebral 
fascia, crosses over or beneath the inferior thyroid artery, and beneath the recur- 
rent laryngeal nerve. As they enter the thorax the two nerves differ in their 
courses. The right nerve runs in front of or behind the subclavian artery and along 
the brachio-cephalic artery to the back of the aortic arch, where it joins the deep 
cardiac plexus. It is usually joined by the superior cardiac branches of the 
right vagus. 
The left superior cardiac nerve, behaving similarly to the right nerve in the 
neck, enters the chest along the side of the left common carotid artery, and crosses 
the aortic arch to join the superficial cardiac plexus. Occasionally it passes behind 
the aortic arch to the deep cardiac plexus. 
Besides the branch described to the internal carotid artery, this ganglion 
supplies filaments, which form a plexus on the external carotid artery and its 
various branches. From the plexus on the facial artery a branch is sent to the 
submaxillary ganglion; and the plexus on the middle meningeal artery supplies 
the otic ganglion with its sympathetic root, and sends a filament to the geniculate 
ganglion of the facial nerve. 644 
THE NERVES. 
The Middle Cervical Ganglion.—The middle cervical ganglion is much the 
smallest of the three. It is sometimes absent and occasionally double. When 
single it is usually situated where the cord crosses the inferior thyroid artery 
opposite the sixth or seventh cervical vertebra. It is joined by gray rami com- 
municantes to the fifth and sixth cervical nerves. It gives off thyroid branches, 
which run on the inferior thyroid artery to the thyroid gland, communicating with 
the recurrent and external laryngeal and the upper cardiac nerves. 
The middle cardiac branch of the sympathetic, springing from this ganglion 
on the right side, descends in front of or behind the subclavian artery and on the 
side of the trachea to the deep cardiac plexus, communicating with the upper 
cardiac nerve and recurrent laryngeal branch of the vagus. 
On the left side this nerve descends between the left carotid and subclavian 
arteries to the deep cardiac plexus, uniting on its way with the left inferior cardiac 
nerve. 
The Inferior Cervical Ganglion.—The inferior cervical ganglion is larger than 
the last, and irregular or semilunar in shape. It lies just over the neck of the 
first rib and under cover of the vertebral artery. To the middle cervical gan- 
glion it is united by two or more cords, one usually passing behind the vertebral 
artery, one in front of it, and one forming a loop round the subclavian artery 
(ansa subclavia Vieussenii). It may blend with the first thoracic ganglion or be 
united to it by a short intervening cord. Gray rami communicantes pass from 
this ganglion to the seventh and eighth cervical nerves. Its efferent branches are 
the inferior cardiac nerve and offsets to blood-vessels. 
The inferior cardiac nerve, springing from this ganglion or the first thoracic, 
on the right side communicates behind the subclavian artery witli the middle 
cardiac and recurrent laryngeal nerves, on the left side usually forms a common 
trunk with the middle cardiac nerve. Both go to the deep cardiac plexus. 
The vascular branches of this ganglion and the first thoracic unite in forming 
the plexus on the vertebral artery, and ascend on that vessel to the basilar artery 
and its branches within the cranium. 
{Note.—The gross anatomy of the cervical sympathetic gives no idea of its 
true anatomical relations as revealed by physiological experiments and patho- 
logical phenomena. The physiological connections as at present understood may 
be summarized as follows : 
1. Pupillo-dilator fibres pass by white rami communicantes from the first, 
second, and third thoracic nerves, ascend in the sympathetic cord to the superior 
cervical ganglion to form arborizations round its cells. Thence gray fibres pass to 
the Gasserian ganglion and reach the eyeball by the ophthalmic division of the 
fifth and long ciliary nerves. 
2. Motor fibres to the involuntary muscles of the orbit and eyelids from the 
fourth and fifth thoracic nerves follow a similar course. 
3. Vasomotor fibres to the head, secretory fibres to the submaxillary gland, 
and pilomotor fibres to the head and neck are derived from the upper thoracic 
nerves and reach their areas of distribution after similar interruption in the supe- 
rior cervical ganglion. 
4. The accelerator fibres of the heart are derived from the upper thoracic 
spinal nerves, and end similarly in the middle and lower cervical ganglia, gray 
fibres in the cervical cardiac nerves completing the connection.) 
The Thoracic Portion of the Gangliated Cord. 
In the thorax the sympathetic cord (Fig. 693) presents eleven, seldom twelve, 
ganglia, the first thoracic ganglion frequently blending with the last cervical. 
When existing separately the first ganglion lies beneath the head of the first rib ; 
the rest, with the exception of the twelfth, lie on the heads of the ribs, under 
cover of the pleura, the intervening cord lying in front of the intercostal vessels. 
The twelfth thoracic ganglion approaches nearer to the middle line, lying on the THE SYMPATHETIC NERVES. 
645 
side of the twelfth thoracic vertebra, between it and the diaphragm, and from it 
the cord descends into the abdomen through the crus of the diaphragm to unite 
the last thoracic to the first lumbar ganglion. 
Rami Cornmunicantes.—Two rami communicantes, sometimes called the exter- 
nal branches, unite each ganglion to its corresponding spinal nerve. Of these one 
is usually white, the other gray. 
INFERIOR CER- 
VICAL GANGLION 
THORACIC NERVES- 
RAMI COMMUNICANTES' 
VISCERAL 
"branches 
VISCERAL 
"BRANCHES 
"THORACIC CHAIN 
OF GANGLIA 
BIGHT PNEU 
' MOGASTRIC 
SPLANCHNIC 
GANGLION 
GREAT 
SPLANCHNIC 
SMALL 
SPLANCHNIC 
BRANCH OF PNEUMOQASTRIC 
“TO SEMILUNAR GANGLION 
CCELIAC AXIS 
SMALL 
SPLANCHNIC" 
.SEMILUNAR GANGLION 
SUPERIOR MESENTERIC 
ARTERY AND PLEXUS 
SOLAR PLEXUS 
QUADRATUS^ 
LUMBORUM 
RENAL PLEXUS 
Fig. 693.—Plan of right sympathetic cord and splanchnic nerves. (Testut.) 
The rami efferentes, called the internal branches, are divisible into an upper 
and a lower series. The upper series proceeds from the upper four or five ganglia 
to the aorta, forming with branches from the splanchnic the thoracic aortic plexus. 
Other slender filaments supply the vertebrae and ligaments, and the second, third, 
and fourth ganglia send branches to the posterior pulmonary plexus. 
The lower series includes the internal branches of the lower six or seven 
ganglia. They form the great, small, and least splanchnic nerves. 
The great splanchnic (visceral) nerve is formed by the convergence on the 
sides of the vertebrae of the internal branches of the fifth or sixth to the ninth or 
tenth ganglia inclusive. These branches and the resulting trunk distribute fila- 646 
THE NER VES. 
merits to the vertebrge and aorta as they descend, the trunks then piercing the 
crus of the diaphragm, and entering the upper angle of the semilunar ganglion. 
It occasionally sends fibres to the suprarenal body and renal plexus. This nerve 
largely consists of medullated fibres, some of which may be traced in the sympa- 
thetic cord till they join the third thoracic nerve. 
The small splanchnic nerve, rising from the ninth and tenth, or ninth, tenth, 
and eleventh ganglia, passes beneath the crus or internal arcuate ligament of the 
diaphragm, to the aortico-renal ganglion, and sometimes sends fibres to the renal 
plexus. 
The least splanchnic nerve, from the last thoracic ganglion, descends beneath 
the internal arcuate ligament to the renal plexus. 
{Note.—It should be remembered that most of the white rami communicantes, 
which pass from the spinal cord to the sympathetic trunk, do so by the thoracic 
nerve ; but that they do not by any means all end in thoracic ganglia. For 
example, the pupillo-motor fibres, vasomotor fibres of the head and neck, secretory 
fibres of the submaxillary gland and accelerator fibres of the heart leave the 
spinal cord by upper thoracic nerves and ascend in the sympathetic trunk to form 
arborizations round the cells of the cervical ganglia. 
In the dog and cat the white rami communicantes from the thoracic nerves 
have been shown to contain, in addition to the above, vaso-constrictor fibres of 
the pulmonary vessels, and of the vessels of the fore and hind limbs, and secretory 
fibres to the sweat glands and pilo-motor fibres to the hair of both limbs, as well 
as viscero-inhibitory fibres to the stomach and intestines, and vasomotor nerves 
to the abdominal vessels.) 
The Lumbar Portion of the Gangliated Cord (Fig. 694) 
There are usually four lumbar ganglia, which lie in front of the vertebral 
bodies on the inner side of the psoas muscles, the left trunk and its ganglia being 
overlapped by the aorta, and the right by the inferior vena cava. 
The ganglia are generally connected somewhat irregularly by white and gray 
rami communicantes with the lumbar nerves, which reach the ganglia by passing 
beneath the fibrous arches of the psoas muscle. Efferent branches join the aortic 
and hypogastric plexuses, and small filaments pass to vertebrae and ligaments. 
{Note.—The lumbar sympathetic is connected with the lower limb, rectum, 
penis, bladder, uterus, and vas deferens, while the other abdominal viscera are 
connected through the solar plexus with the lower six thoracic nerves.) 
From these ganglia and the intervening mesh work are given off plexuses, which 
correspond in name and distribution to the upper branches of the abdominal aorta. 
Thus the diaphragmatic or phrenic plexuses spring from the upper part of the semi- 
lunar ganglia. They accompany the phrenic arteries, and are joined by the 
phrenic nerves. A ganglion is formed at their junction on the right side (want- 
ing on the left side) whence branches pass to the vena cava, suprarenal body, and 
hepatic plexus, 
Suprarenal plexuses accompany the arteries of the same name from the 
phrenic artery, aorta, and renal artery. They are thus derived from the phrenic, 
solar and renal plexuses. They contain many minute ganglia. 
The renal plexus springs from the aortico-renal ganglion, and solar and aortic 
plexuses, and receives the small splanchnic nerve. It accompanies the renal 
artery to the kidney substance, and gives branches to the suprarenal body, sper- 
matic plexus and ureter, and on the right side the vena cava. 
The spermatic plexus springs from the renal and aortic plexuses and accom- 
panies the spermatic artery to the testis, receiving an accession from the pelvic 
sympathetic along the vas deferens. 
In the female it is represented by the ovarian plexus to the ovary and uterus. 
The coeliac plexus is large in accordance with the size and extensive distribu- 
tion of the coeliac axis. It gives off' secondary plexuses corresponding in names THE SYMPATHETIC NERVES. 
647 
and distribution to the branches of that vessel. Of these plexuses the hepatic 
and coronary are joined by branches of the left pneumogastric, and the splenic 
plexus is reinforced from the right pneumogastric. 
The superior mesenteric plexus is derived from the solar plexus, superior 
mesenteric ganglion, and right pneumogastric. It is distributed to the intestine, 
at first following the branches of its artery closely ; but its finer filaments leave 
the vessels. 
The aortic plexus is formed of two cords and an intervening network, which 
descend on the abdominal aorta beneath the superior mesenteric artery. It is 
GREAT SPLANCHNIC 
.SEMILUNAR GANGLION 
LOWEST THORACIC- 
GANGLION 
UPPER lumbar' 
GANGLION 
•SOLAR PLEXUS 
SUPERIOR MESEN- 
TERIC PLEXUS 
ABDOMINAL AORTA- 
RENAL PLEXUS- 
SMALL IN- 
TESTINE 
AORTIC PLEXUS- 
LUMBAR SYMPATHETIC- 
VENA CAVA INFERIOR- 
COMMISSURE 
AORTIC AND HYPOGAS-' 
TRIG PLEXUSES 
..INFERIOR MESEN- 
TERIC PLEXUS 
COMMON ILIAC- 
ARTERY 
UPPER SACRAL / 
GANGLION L 
SIGMOID 
COLON 
... VESICAL 
PLEXUS 
BLADDER 
[. VESICULA 
S SEMINALIS 
| SPERM ATIC 
| PLEXUS 
J- PROSTATE 
RECTUM 
HYPOGASTRIC 
PLEXUS "I 
Fig. 694.—Lower half of right sympathetic cord. (Testut, after Hirschfeld.) 
joined by branches from the lumbar ganglia, gives off the inferior mesenteric 
plexus and branches to the spermatic plexus and inferior vena cava, and ends 
below in the hypogastric plexus. 
The inferior mesenteric plexus is derived from the aortic. It corresponds in 
distribution and communications with the artery of the same name. 
The Hypogastric Plexus.—Branches from the aortic plexus descend on the 
aortic bifurcation to the front of the fifth lumbar vertebra, where they are joined 
by strong fibres from the lower lumbar sympathetic ganglia, which cross over the 
common iliac arteries. These form together in front of the fifth lumbar vertebra 
a coarse mesh work invested in dense fibrous tissue, called the hypogastric plexus. 648 
THE NERVES. 
It contains no ganglia. In front of the sacrum it splits into two lateral portions, 
which join the pelvic plexuses. 
The Pelvic Plexus.—Lying on each side of the rectum and bladder in the 
male, and of the rectum, vagina, and bladder in the female, is a network, rich in 
ganglia where the fibres interlace, formed by the continuation of the hypogastric 
plexus, offsets from the upper sacral ganglia, and branches from the second, third, 
and fourth sacral nerves. This is the inferior hypogastric or pelvic plexus. From 
this branches are distributed to the pelvic viscera, which at first follow the 
branches of the internal iliac artery, their terminal twigs leaving the vessels and 
entering the substance of the organs. Thus the following secondary plexuses are 
formed, viz : 
The hemorrhoidal plexus, derived from the upper part of the pelvic plexus, 
accompanies the middle hemorrhoidal artery and joins with the plexus on the 
superior hemorrhoidal vessels in supplying the rectal wall. 
The vesical plexus is a close network, rich in spinal fibres, which is best marked 
over the sides and base of the bladder. It gives off plexuses to the vasa deferentia 
and vesiculse seminales, of which the former join the spermatic plexuses and the 
latter receive communications from the prostatic plexus. 
The prastatic plexus, lying between the prostate and levator ani, sends fibres 
backward to join the plexuses on the vesicuhe seminales and forward through the 
triangular ligament to the corpus cavernosum. 
The vaginal plexus is largely composed of spinal nerves. It supplies the 
mucous membrane and erectile tissues of the vagina, and sends twigs to the 
clitoris. 
The uterine plexus is mainly derived from the pelvic continuation of the hypo- 
gastric plexus and third and fourth sacral nerves. It enters the broad ligament, 
communicates there with the ovarian plexus, and is mainly distributed over the 
neck and lower part of the body of the uterus. It contains numerous ganglia. 
The apparent hypertrophy of these nerves in pregnancy is due to thickening of 
their fibrous sheaths. 
The Sacral Portion of the Gangliated Cord. 
In the pelvis the sympathetic trunks, much diminished in size, descend on 
the inner sides of the anterior sacral foramina, a ganglion usually appearing for 
each of the four upper sacral nerves. In front of the coccyx the two cords unite 
in one ganglion, called the ganglion impar, which is usually connected with both 
coccygeal nerves. 
Short rami communicantes connect each of these ganglia with one or more of 
the sacral nerves, and rami efferentes join the pelvic plexus, while others form a 
plexus on the middle sacral artery or pass to the sacrum and coccyx and their liga- 
ments. Through the pelvic plexus the pelvic viscera are supplied with motor, 
vasomotor, and secretory fibres. 
The Prevertehral Plexuses of the Sympathetic.—These plexuses are named 
respectively the cardiac, solar, hypogastric, and pelvic. Each plexus is single 
and median, and is composed of nerves derived from both sympathetic trunks, 
with others derived from the cerebro-spinal nerves. Ganglia are developed in 
their meshes and from them subsidiary plexuses are formed. 
The Cardiac Plexus.—Beneath and behind the aortic arch is a meshwork of 
nerve-fibres, which for convenience of description is divided into a superficial and 
a deep portion, though the two form one continuous plexus. The nerves enter- 
ing into this plexus are the superior and inferior cervical cardiac branches of the 
vagi, the thoracic cardiac branches of the same nerves, and the superior, middle, 
and inferior cardiac branches of the sympathetic. 
Of these nerves the superior cardiac branch of the left sympathetic trunk, and 
the lower cervical cardiac branch of the left pneumogastric form, in the concavity 
of the aortic arch, the superficial cardiac plexus. In its meshes is a small ganglion, THE SYMPATHETIC NERVES. 
649 
the ganglion of Wrisberg. It sends branches to the right coronary plexus and 
left anterior pulmonary plexus, the latter accompanying the left branch of the 
pulmonary artery. 
All the other cardiac nerves above mentioned join in forming the deep cardiac 
plexus which lies in the bifurcation of the trachea behind the aortic arch. From 
it branches are distributed to both auricles, both coronary plexuses, and both pul- 
monary plexuses. 
Of the coronary plexuses the right is the smaller. It is derived from both 
cardiac plexuses, its branches surrounding the root of the aorta. It descends on 
the right coronary artery, sending filaments to ramify between the pericardium 
and muscular wall of the heart, the ultimate fibres entering the muscle substance. 
The left coronary plexus is derived from the deep cardiac plexus. It passes 
between the pulmonary artery and left auricular appendix, and accompanies the 
left coronary artery. 
The Solar or Epigastric Plexus.—Lying in front of the crura of the diaphragm 
and at the sides of the aorta, just after that vessel appears in the abdomen, are 
two large ganglionic masses united to each other by a coarse network of nerve 
fibres, which surrounds the origins of the coeliac axis and superior mesenteric arte- 
ries. This is the solar or epigastric plexus. It lies behind the stomach, above the 
pancreas, and between the suprarenal bodies. 
Each ganglionic mass presents one large irregular body at its upper part, 
called the semilunar ganglion, which receives the great splanchnic nerve at its 
upper angle. 
Continuous with the semilunar ganglion, but marked off from it by a con- 
striction, is a smaller body, the aortico-renal ganglion, which receives the small 
splanchnic, and gives off the greater part of the renal plexus ; while a still smaller 
body, lying to the right of the superior mesenteric artery, forms the superior 
mesenteric ganglion. 
Through this plexus the abdominal viscera above the pelvis are connected 
with the lower six thoracic ganglia and thoracic spinal nerves, and it is significant 
that these last supply the abdominal wall. THE ORGANS OF THE SPECIAL 
SENSES. 
THE five senses of touch, taste, smell, hearing, and sight have as their special 
organs the skin, the tongue, the nose, the ear, and the eye respectively. Of 
the five the commonest, the least specialized sense is that of touch, and its organ 
is of the greatest extent and the smallest differentiation. The other senses dis- 
play progressively increasing delicacy in the order as named above : touch is 
excited only by the impact of some body; taste requires the contact of the solu- 
tion of a sapid substance; smell is produced by the impression of volatilized 
materials ; hearing results from the agitation of the endolymph (a fluid contained 
in the ear), whose wavelets beat upon the auditory surface; and sight is called 
into being only by the undulations of the ether which is believed to pervade all 
space. The organs of the senses above the tactile are either localized, inward 
extensions of the integument or inversions of it, which have become completely 
isolated. In every case there is a modification of the epithelium of the area 
concerned, amounting to a specialization. These epithelial cells have already 
been mentioned, as forming the variety called neuro-epithelium for the reason that 
they are so peculiarly related to specialized portions of the nervous system. From 
all of these facts it will be seen that tactile sensibility is the humble progenitor 
of every other sense, and that, unlikely as it seems to one who does not consider 
everything which is involved, sight is but touch glorified. 
THE SKIN. 
W. KEILLER. 
AS one of the main functions of the skin is ;the sense of touch, it may be con- 
veniently described among the sensory organs ; though, in addition to serving 
this function, it is protective, and excretory, and an important regulator of the 
body temperature. 
It consists (Fig. 695) of a deep layer, called the true shin or corium, which 
contains nerve endings, vessels, sweat glands, hairs, and sebaceous glands, embedded 
in a fibrous matrix ; and a superficial, epithelial layer, the epidermis or cuticle, 
which covers and protects the whole, and furnishes the epithelial elements of the 
glands and hairs just mentioned. 
651 652 
THE ORGANS OF THE SPECIAL SENSES. 
HAIR 
EPIDERMIS^ 
IHORNY 
I LAYER 
J LAYER 
PAPILLA OF 
DERMIS 
.DUCT OF SEBA- 
CEOUS GLAND 
SEBACEOUS 
G LA N D 
DERMIS< 
-ROOT OF HAIR 
•HAIR FOLLICLE 
ADIPOSE TISSUE 
GLOMERULUS OF 
SWEAT GLAND 
BULB OF HAIR 
PAPILLA OF HAIR 
SUBCUTANEOUS 
AREOLAR TISSUE 
Fig. 695.—Vertical section of the skin. (Testut.) 
ADIPOSE 
Ur RECTOR PI LI 
Examined on the surface the skin varies much in texture, being rough and 
thick on the palms of the hands and soles of the feet, even of the newborn child; 
of medium thickness on the scalp and dorsal surface of the trunk, and thinnest 
on the ventral surface of the trunk and inner sur- 
faces of the limbs. It is marked throughout by 
furrows which differ in character. Over most of 
the body the furrows are like those on the back of 
the hand, shallow and intersecting each other so as 
to enclose angular areas, the hairs usually springing 
from intersecting points. On the palm and sole the 
furrows run in parallel lines, forming definite 
patterns (Fig. 696), which, while they correspond in 
the main, are peculiar to each individual, and never 
change throughout life in spite of the passage of 
the soft palm of babyhood into the horny hand of 
age and toil. Hence the value of the hand im- 
pression in wax as a means of identification. These 
ridges and grooves are formed in the true skin on 
which the cuticle is accurately moulded. Deep and 
long grooves subtend the joints. The true skin 
blends with the loose subcutaneous tissue, and by 
Fig. 696.—Arrangement of the 
papillary folds on the palmar surface 
of the distal segment of the thumb. 
(Testut.) 
its agency is made freely movable on the deep fascia. On the palms, soles, scalp, 
and pinna, however, the skin is closely bound to the deeper aponeurotic structures. 
The hairs and nails are modified epidermis, the sweat and sebaceous glands epi- 
thelial invaginations. 
The Epidermis (cuticle, scarfskin) is formed of stratified epithelium in many 
layers. It varies from to of an inch in thickness, being thickest on the 
palms and soles. It is roughly divisible into two strata, the Malpighian layer THE SKIN. 
653 
(which includes the four deep layers to be described) and a superficial, horny layer. 
Next to the true skin is a single layer of columnar cells, the parent cells of the 
rest; then come polyhedral cells to a considerable depth, each communicating with 
its neighbors by strands of protoplasm, giving them a prickly appearance (hence 
the term “ prickle cells ”). This stratum is covered by two thin strata, which ex- 
hibit changes antecedent to their assuming the characters of the horny layer, 
namely the stratum granulosum and the stratum lucidum. Their peculiar appear- 
ance is due to a progressive accumulation in droplets of a substance called eleidin. 
Superimposed on these is the horny layer (stratum corneum), the cells of which 
become gradually more flattened toward the surface, lose their nuclei, and have 
their substance converted into keratin. During life the superficial cells of this 
layer are being constantly shed and renewed from those beneath. The pigment 
in the skin of the negro, as well as that of the nipple and elsewhere in white 
races, is found in the deepest cells of the Malpighian layer. 
The True Skin (cutis vera, derma, corium) consists of a fibrous matrix with 
vessels, lymphatics, and nerves embedded therein. It blends gradually with the 
superficial fascia, in which, with the exception of that on the penis, scrotum, 
labia minora, and eyelids, clusters of fat cells are accumulated. This loose areolar 
subcutaneous layer enables the skin to move freely on the deep fascia. The true 
skin is formed of interlacing bundles of white fibrous tissue with numerous 
elastic fibres and connective-tissue corpuscles. In connection with the hairs, 
and in the cutis vera of the scrotum, penis, perineum, areola of the nipple, 
and the nipple itself, smooth muscular fibres are found in fasciculi. The free 
surface of the corium is raised to form the ridges already described as seen on 
the surface of the skin, and on their summits simple and compound papillae are 
developed, which are received into pits on the deep surface of the cuticle (Fig. 
697). These papillae are most numerous where sensation is most acute, as on the 
Fig 697 Papillse of the skin. The epidermis has been loosened by maceration and lifted off, and its under 
surface shows the pits into which the papilla fitted. Sweat-glands are stretched or broken across. (Testut.) 
pulp of the fingers. On the palm, sole, and nipple they are numerous and 
measure from to inch in height. They are few and small on the face, 
and in some parts are altogether absent. Some of these papillae have vascular 
loops prolonged into them, some have touch-corpuscles (Fig. 698). 
The bloodvessels of the skin are found in the cutis vera only. They form a 
capillary network from which branches pass to the hairs, glands, and fat, and 
capillary loops project into the papillae. The lymphatics form a deep and super- 654 
THE ORGANS OF THE SPECIAL SENSES. 
ficial network accompanying the vessels. As in other tissues they originate in the 
intercellular spaces. 
The cutaneous nerves form a subepithelial plexus, from which twigs are given 
CAPILLARY- 
LOOP 
SUBCUTANEOUS 
CAPILLARY 
PLEXUS 
Fig. 698.—Papillae of the skin, showing the arrangement of the vessels and nerves. (Testut.) 
CUTANEOUS NERVES 
otf to end in special terminal bodies of varied character, or, again, each fibre may 
divide and redivide dichotomously, soon losing its medullary sheath, the axis 
cylinder ultimately breaking up into its constituent fibres, which end in minute 
DEEPEST LAYER OF 
THE EPIDERMIS 
CONNECTIVE TISSUE. 
OF DERMAL PAPILLA 
MYELIN SHEATI 
TIS- 
SUE NUCLEUS 
FIBROUS ENVELOP 
OF CORPUSCLE 
,NAKED AXIS- 
CYLINDER 
CONNECTIVE TIS-_ 
SUE SEPTUM 
BUNDLE OF FIBRILS EMERG- 
ING FROM NODE OF RANVIER 
TACTILE CELI 
TACTILE DISC 
MYELIN SHEATH- 
-PERINEURIUM 
Fig. 699.—Touch-corpuscle in vertical section. Semidiagrammatic. (Testut.) 
knob-like processes among the cells of the Malpighian layer. The forms of end 
organs are very numerous, but we will describe only those known as touch-cor- 
puscles, end bulbs, and Pacinian bodies. 
Touch-corpuscles (Fig. 699) are found in the dermal papillae of the palm and 
sole, nipple, conjunctiva, lips, and tip of the tongue. They are ovoid bodies with THE SKJN. 
a fibrous capsule sending septa into the interior. One or more medullated fibres 
either at once enter the corpuscle, or first wind round it several times. On 
entering, the nerve loses its medullary sheath, and its axis cylinder breaks up into 
fibrils, which ramify minutely through the corpuscle, oval swellings forming on 
the branches. 
End bulbs of spheroidal form are found in the papillae of the skin of the lips, 
of the glans penis and glans clitoridis, in the conjunctiva, in the raucous mem- 
brane of the cheeks, soft palate, tongue, epiglottis, and rectum. Similar organs 
are found in the sheaths of nerve trunks. These bodies consist of a connective- 
tissue capsule containing nucleated cells, among which the axis cylinder of the 
nerve terminates. 
Pacinian Corpuscles (Fig. 700) are small, seed-like bodies, T*g- to yL- of an inch 
long, and f° 2V °I au inch thick, found in clusters on the digital nerves of 
the hand and foot, and in many other situations. A Pacinian corpuscle is lamel- 
lated like an onion, having in some cases 40 to 60 coats, the inner laminae thinner 
and more closely packed than the outer. The lamellae are fibrous in character, 
_KNOB-LIKE 
ENDINGS 
KNOB-LIKE.. 
ENDINGS 
TERMINAL 
BRANCHES- 
branch.es 
JNNER LA- 
ME LL/E 
.OUTER LA- 
ME LL/E 
—CORE 
AXIS-CYLINDER 
"entering CORE 
PERINEURIUM BECOMING 
CONTINUOUS WITH TUNIC 
—AXIS-CYLINDER 
—NERVE FIBRE 
Fig. 700.—Pacinian corpuscle in vertical section. (Testut.) 
continuous with the layers of the perineurium, and have lymph-spaces between them. 
In the centre of the body is an elongated, homogeneous core, into which the 
nerve penetrates. It courses along the middle of the core till it approaches the 
opposite end of the corpuscle, and then divides into processes, which end in 
bulbous extremities. Each corpuscle is supplied with a small capillary vessel, 
and has a distinct fibrous capsule. 
The nails and hairs are formed of modified epithelium on a special dermal 
substratum. 
NAILS AND HAIRS. 656 
THE ORGANS OF THE SPECIAL SENSES. 
Nails. 
Each nail (Figs. 701-703) consists of a body, which is translucent, showing 
readily the red glow of the underlying capillary vessels, except at its proximal 
extremity, where it is more opaque over a crescentic area 
called the lunula. The opacity and consequent whitish color 
is due to the greater thickness of the Malpighian layer in 
this situation. The free edge of the nail overhangs the 
tip of the digit; its root is embedded proximally in a 
deep groove in the skin, from which an epidermal mantle 
projects over the lunula. Its lateral borders are sunk in 
furrows, which have an overhanging nail-wall of npfolded 
skin. From free edge to lunula the nail is closely ad- 
herent to an epidermal nail-bed, but from the lunula to 
the proximal margin of the root this bed is called the 
matrix, because it is here only that the growth of nail 
takes place. The nail-substance consists of flattened, 
closely-packed cells, which, on addition of an alkali, swell 
up and are seen to retain their nuclei; hence they repre- 
BODY 
LUNULA,... 
MANTLE 
(Testut.) 
Fig. 701. Thumb - nail. 
sent a condensed stratum lucidum. The nail-bed is essentially the Malpighian 
layer, its cells being more heaped up over the matrix, as already stated. Ihe 
dermal constituent of the matrix is exceedingly vascular, and studded with large 
vascular papillae, while the derma under the nail-bed is raised into parallel longi- 
tudinal ridges. 
With a few exceptional areas the whole skin is studded with hairs, varying 
in texture from the fine down (lanugo), scarcely projecting beyond the hair 
Hairs (Figs. 704, 705). 
MANTLE 
BODY 
LUNULA 
BED) 
iBODY 
FREE 
MARGIN 
NAIL-WALL 
ROOT 
FINGER 
PULP 
PHALANX 
BED 
MATRIX 
Phalanx 
Fig. 702.—Nail in longitudinal section. The line axr indi- 
cates the plane of the section shown in the following figure. 
(Testut.) 
Fig. 703.—Nail in transverse section. The 
line yy indicates the plane of the section shown 
in the preceding figure. (Testut.) 
follicles, found on the eyelids and inner surface of the labia majora, to the long 
hairs of the scalp, and short, crisp, thick hairs of the beard and pubes. The skin 
of the palms and soles, the dorsal surfaces of the third phalanges of the fingers 
and toes, the inner surface of the prepuce in the male, the labia minora in the 
female, the glans penis and glans clitoridis are devoid of hairs. In straight- 
haired races the hairs are thick, coarse, and cylindrical, in crisp-haired races thin 
and flattened, being oval on section. Dark hairs are coarser than those of lighter 
color. 
The portion of a hair projecting beyond the surface is its shaft or stem, that 
embedded in the skin is its root. The root ends in a bulbous enlargement, which is 
implanted on a dermal papilla. It is contained in an invaginated tube of skin, 
called a follicle, which furnishes it with an outer dermic and an inner epidermic 
coat. 
A hair has on its surface a single layer of thin, imbricated, scale-like cells, THE SKIN. 
657 
their free margins pointing outward. These form the hair cuticle. Next comes 
the cortical substance, some hairs having in addition a medulla or pith. The 
cortical substance consists of closely set elongated cells, which still retain a trace 
of a nucleus. The cells and intercellular spaces contain pigment, varying in 
amount with the color of the hair. Between the cells are air-spaces, the air being 
most abundant in white hair. In the thick, short hairs of the pubes, the hair of 
the beard, and in white hair in the scalp there is a central pith. It is composed 
of irregular, polyhedral cells, containing many air-spaces. The pith does not 
extend to the point of the hair, is not present in children under five years of age, 
and is not found in the colored hairs of the scalp, or in fine hairs. 
Toward the bulb the cells which form the hair become polyhedral, and 
resemble the cells of the Malpighian layer. The bulb expands to enclose a vas- 
cular papilla of cutis vera. 
The hair follicle (Fig. 705) has dermic and epidermic constituents. The 
dermic coat consists of three layers. The outer layer is formed of longitudinally 
SPACE FOR PASSAGE OF 
SEBACEOUS MATTERJ 
HAIR 
- EPIDERMIS 
DUCT OF GLAND 
>ARRECTO- 
RES PI LI 
I 
SEBACEOUS_ 
GLAN D 
-SEBACEOUS 
GLAND 
DERMIS 
ROOT- 
DERMAL COAT 
HYALINE COAT 
OUTER EPIDER- 
MAL SHEATH 
INNER EPIDER-. 
MAL SHEATH 
—BULB 
—PAPILLA 
Fig. 704.—Vertical section of the skin, showing a hair and its follicle. (Testut.) 
arranged white fibres with connective-tissue corpuscles, and numerous vessels 
and nerves. It is continuous with the reticular layer of the corium. Within 
this is a layer of circular fibres, which appears to represent the papillary layer of 
the corium, and within these is a structureless lamina (the hyaline layer), repre- 
senting the basement membrane of foetal skin. These two inner layers extend 
out from the bottom of the follicle to the openings of the sebaceous glands. The 
epidermic coat is divisible into two parts, the outer root-sheath, which is simply 
the Malpighian stratum of the epidermis, and the inner root-sheath, which may 
be taken as representing the stratum lucidum, and presents three characteristic 
layers. On the outside, and next to the outer root-sheath is Henle’s layer, a 
single layer of non-nucleated, flattened cells ; then comes Huxley’s layer, consisting 
of polyhedral cells, two or three deep ; and lastly the cuticle of the root-sheath, a 658 
THE ORGANS OF THE SPECIAL SENSES. 
single layer of flattened cells, imbricated on each other, so as to fit into the 
depression on the hair cuticle, their free edge thus being directed downward. All 
the layers of the root-sheath blend at the bottom of the follicle, and become con- 
tinuous with the cells of the hair bulb. The inner root-sheath ceases where the 
sebaceous gland enters the hair follicle. Lastly the stratum corneum dips a little 
way into the mouth of the follicle. 
The hair-papilla is a fungiform process, consisting of connective tissue with 
MEDULLA 
CORTEX 
HAIR CUTICLE 
■ HENLE’S LAYER 
-HUXLEY’S LAYER 
HAIR CUTICLE 
INTERNAL 
EPIDERMIC 
COAT 
EXTERNAL 
EPIDERMIC 
COAT 
HYALINE^ 
LAYER 
DERMAL 
SHEATH* 
-BULB 
-PAPILLA 
Fig. 705.—Vertical section of the root of a hair. (Testut.) 
CAPILLARY LOOP 
pigment cells and blood-vessels, which projects into a cup-shaped cavity in the 
bulb. 
Muscles of the Hairs.—Slender bundles of unstriped muscle, the arrectores 
pilorum (“ erectors of the hairs ”), arise from the superficial layers of the coriura 
and run obliquely inward to be attached to the fibrous coat of the hair follicles 
on the side toward which the hairs lie. They cause the hairs to stand erect. 
Nerves are supplied to the fibrous coat and outer root-sheath, and perhaps to 
the papilla. They form a delicate plexus round the root-sheath. 
The Sebaceous Glands (Fig. 704). 
x 
The sebaceous (“ fat ”) glands usually open into the hair follicles, and are 
found wherever hairs are. But in addition they occur on the labia minora, pre- 
puce, glans penis and glans clitoridis, the red edge of the lips, and, in a modified 
form, as Meibomian glands, in the eyelids. They are small on the head, large on 
the nose and most of the face, raons Veneris, labia majora, and scrotum. They 
are seldom simple, usually compound, saccular glands with short ducts, and lie 
between the hairs and their arrector muscles, so that the action of the arrectors 
will expel their fatty secretion. The number of acini in a single gland varies 
from four or five to twenty. THE SKIN. 
659 
The Sweat-Glands (Fig. 695). 
Except in the depths of the external auditory meatus and on the tympanic 
membrane, sweat-glands are found over the whole integument. They are most 
numerous on the palms of the hands and soles of the feet, 2800 to the square 
inch ; on the back of the neck and trunk there are only 400 to 600 in the same 
area. They vary much in size, being largest in the axilla and groin. Krause 
estimates their total number as about two millions. 
A sweat-gland is an invaginated, epithelial tube, which sinks through the cer- 
ium into the subcutaneous fatty tissue, and there coils up into a ball. Thus it is a 
simple tubular gland, the coiled-up extremity being the secreting portion, the 
straight tube its excretory duct. In the epidermis the duct is a simple channel 
with no definite walls, and where the horny layer is thick it twists in cork-screw 
fashion. As it passes through the corium, the duct derives from it a richly 
vascular fibrous coat, within which is a basement membrane. The duct, much 
smaller than the coiled, secreting portion 'of the tube, is lined by small poly- 
hedral cells, two deep, whose free surface is condensed into an appearance sug- 
gesting a delicate cuticle. In the secreting segment a layer of smooth muscular 
fibres, longitudinally arranged, is placed next the basement membrane, and on 
this a single layer of columnar cells with nuclei near their attached extremities. 
The ceruminous glands of the ear and the glands of Moll in the eyelid are modi- 
fied sweat-glands. The sweat-glands in the axilla and round the anus and, of 
course, the ceruminous glands have an oily secretion ; the rest secrete a colorless, 
slightly turbid, aqueous fluid, the perspiration. THE TONGUE. 
F. H. GERRISH. 
THE tongue has various functions. It is necessary for articulate speech, per- 
forms valuable service in the processes of mastication and deglutition, 
possesses tactile sensibility to a high degree, and is the principal organ of taste. 
It is only in its sensory relations that it will be considered in this place. Its 
other features will be de- 
scribed in connection with 
the other parts of the 
month and pharynx. 
The mucosa of the dor- 
sum (Eig. 706) is the only 
part of the tongue having 
gustatory capacity. The 
anterior two-thirds of this 
surface presents in the 
mouth, the posterior third 
in the pharynx, the bound- 
ary between the two being 
marked by a line of large 
projections, the circumval- 
late papilla;, arranged like 
an inverted V, with widely 
spread branches. 
The oral part of the 
dorsum is besprinkled with 
smaller processes, the 
fungiform papillae, and 
elsewhere this surface is 
completely covered with 
closely set ranks of a third 
variety, the filiform papillae 
marshalled for the most 
part, especially behind, in 
lines nearly parallel on 
each side with the circum- 
vallate. 
PHARYNX 1| 
UVULA 
-TONSIL 
-EPIGLOTTIS 
CIRCUM- 
*• VALLATE 
PAPILL/E 
The pharyngeal part of 
the dorsum is occupied by 
mucous glands, and small 
lymphoid masses, struct- 
Fig. 706.—Dorsal surface of the tongue. (Testut.) 
urally similar to the tonsils, and arranged in lines parallel with the circumvallate 
papillae. 
The Circumvallate (“ walled-around ”) Papillae (Fig. 707) vary in number from 
seven to twelve. The base of each is broad, its summit wider still. Its core is 
a prolongation of the corium of the mucous membrane, and many secondary THE TONGUE. 
661 
'papillae project from its top. A thick, stratified epithelium, similar to that of 
the skin, covers the papilla completely, the superficial layers giving no evidence 
of the existence of papillae beneath. Around the main papilla at a little distance 
is a circular rampart, whose top is as high as that of the papilla, and its structure 
identical with that of the latter. Occupying the entire thickness of the epithe- 
lium of the lateral surface of the j)apilla is a multitude of flask-shaped bodies, 
called taste-buds (Fig. 708). They are composed of two kinds of epithelial cells, 
gustatory and sustentacular, packed together closely. 
Fig. 707.—Circumvallate papilla in vertical section, showing arrangement of the taste-buds and nerves, 
(Testut.) 
A gustatory cell is slender, except at its centre, which is bulged in every 
direction by a large nucleus. Its proximal end is often branched, and extends to 
the corium ; its distal extremity is surmounted by a stiff cilium, which reaches 
almost to the surface. The sustentacular cells are fusiform, and are mostly 
situated in the peripheral parts of the taste-bud, though some of them are 
mingled with the gustatory. They furnish mechanical support to the other cells, 
and form a firm casing to the bud. The stratified, flattened epithelium, which 
clothes the papilla, presents a perforation, called a gustatory pore, at the spot 
where the distal extremity of the 
taste-bud approaches the surface, 
and thus the hairs of the gustatory 
cells can be affected by the direct 
contact of sapid solutions. 
Taste-buds are found, also, in the 
wall surrounding the papilla, pre- 
senting their open ends toward the 
intervening ditch, as do those of 
the papilla itself. 
The Fungiform (“ mushroom- 
shaped ”) Papillae (Fig. 709) are 
pediculated knobs, upon the rounded 
upper surface of which are many 
Fig. 708.-Taste-buds. (After Engleman.) 
secondary papillae. In the fungiform are found many taste-buds. 
The Filiform (“ thread-shaped”) Papillae (Fig. 709) are small, somewhat cylin- 
drical, and bear secondary papillae, upon which the epithelium is particularly 
dense, and drawn out into long, tapering threads. 
To all of the varieties of papillae nerves are supplied, entering through their 
bases, and sending filaments between the epithelial cells, but not establishing 
absolute continuity with them. The glossopharyngeal furnishes the hind third 
of the mucosa of the dorsum of the tongue, the lingual the remainder. 
Taste-buds are scattered over the dorsal surface independently of papillae, and 
are especially numerous in the posterior part. 662 
THE ORGANS OF THE SPECIAL SENSES. 
Fig. 709.—Semidiagrammatic view of a portion of the mucous membrane of the tongue. Two fungiform 
papilla are shown. On some of the filiform papilla the epithelial prolongations stand erect, in one they are 
spread out, and in three they are folded in. (Testut.) 
Other Organs of Taste. 
Although the tongue is the principal organ of the sense of taste, it has not a 
monopoly of this peculiar endowment. Taste-buds are found in the mucosa of 
the back part of the hard palate, on the anterior surface of the soft palate, and 
to some extent in other parts of the pharynx. THE NOSE. 
W. KEILLER. 
THE nose is the organ of the sense of smell. It forms on the face a prominence 
partly bony, partly cartilaginous. Its root springs from the nasofrontal 
groove, except in the Grecian type, where the dorsum of the nose is in a straight line 
with the forehead. The mesial ridge is called the dorsum, of which the upper 
bony segment forms the bridge. It ends below in the tip, which is continuous 
with the horizontal free edge of the septum, called the columna nasi. The sides 
of the nose form an angle with the face, which increases as it descends (the naso- 
facial angle). The rounded, lateral boundary of the nostril is called the ala. 
The Nasal Cavity consists of two fossa:, separated from each other by a mesial 
septum. They open anteriorly by the two nostrils or anterior nares, and posteriorly 
by the posterior nares or choance (“ funnels”) into the upper part of the pharynx. 
The anterior nares are guarded by hairs, vibrissce, which spring from their inner 
surface. Each expands into a smooth-walled, front chamber called the vestibule, 
the rest of the nasal cavity being divisible into three channels called meatuses. 
The width of the nostrils bears in different races a very varying relation to its 
length measured vertically. 
The shin of the nose is fine and movable over the bony part, thick, adherent, 
and closely studded with large sebaceous glands over the tip and alse. Its vessels 
.CARTILAGE OF 
LEFT ALA 
Fig. 710.—Septal cartilage of the nose, seen in sagittal section at the right of the middle line. (Testut.) 
are derived from the ophthalmic and facial, and, being terminal, readily indicate 
the state of circulation. The lymphatics drain into the submaxillary nodes. The 
sensory nerves are derived from the infratrochlear, nasal, and infraorbital branches 
of the fifth ; the motor nerves, from the seventh. The muscles have been described 
among the muscles of the face. 
663 664 
THE ORGANS OF THE SPECIAL SENSES. 
The Nasal Cartilages. 
At least two-thirds of the facial portion of the nose, and one-third of its sep- 
tum have a framework of cartilage. Beginning with the cartilage of the septum 
(Fig. 710), the mesial plate is quadrilateral in form, completing the nasal septum. 
It articulates above with the nasal bones, behind with the vertical plate of the 
ethmoid, postero-inferiorly with the vomer, and nasal spine of the maxillae, and 
antero-inferiorly with the septal portion of both lower lateral cartilages. In the 
foetus, and occasionally in the adult, it sends a long limb or processus posterior 
into the ethmo-vomerine suture. The upper lateral cartilages (Fig. 711) are two 
lateral wings of the septal cartilage, which bend over to form part of the sides of 
the nose. They are triangular in shape, continuous with the septal cartilage 
in the middle line above, but separated from it below by a fissure, and articulate 
posteriorly with the free margins of the nasal 
bone and nasal processes of the maxilhe, small 
islets of cartilage sometimes intervening (car- 
tilagines epactiles). Inferiorly they articu- 
late with the lower lateral cartilages. Each 
lower lateral cartilage consists of two plates 
joined at an acute angle along the dorsum of the 
nose. The mesial plate is placed in apposition 
with its fellow to form the antero-inferior 
angle of the septum and part of the columna, 
a deep groove separating them in the middle 
line in front, while above they articulate with 
the cartilage of the septum. The lateral plate 
forms the lower part of the side of the nose, 
articulating above with the upper lateral car- 
tilage, and posteriorly with the superior max- 
illa, two or three separate cartilages (minor or 
quadrate cartilages) being placed in the fibrous 
tissue which joins them. The lateral cartil- 
ages keep the anterior nares expanded. The 
ala contains no cartilage, but consists of skin 
ACCESSORY 
CARTILAGES 
Fig. 711.—Front view of the skeleton of 
the nose. The upper lateral cartilage is 
labelled “lateral cart.,” the lower, “alar 
cart.” (Testut.) 
and fibrous tissue only. Tough fibrous tissue fills in the interstices of this frame- 
work, and is continuous with periosteum and perichondrium. Two small strips 
of cartilage, not always separate from the septal cartilage, are interposed between 
the latter and the vomer. They enclose the organ of Jacobson, and are rela- 
tively large in the foetus and in animals in whom the organ of Jacobson is 
well developed. 
THE NASAL FOSS.® 
The nasal fossae (Figs. 712, 713) have a very different appearance as seen with 
their mucous covering from that of their bony framework as described in the sec- 
tion on osteology. This difference is mainly due to the thickness of the mucous 
membrane, the complete closure of nervous or vascular foramina, and the narrow- 
ing of those openings which conduct to the air sinuses. 
The upper part of each fossa, which corresponds in extent to the superior 
turbinate, is narrowed above at the roof, expanded below. It is the only part of 
the fossa which possesses the olfactory function. Below this the walls are nearly 
parallel. The anterior part of the fossa is unbroken by irregularities, and forms 
an expanded vestibule, into which the anterior aperture or nostril leads. Behind 
this each fossa has three awning-like processes projecting from its outer wall, 
formed by the turbinate bones, which, when covered with raucous membrane, 
nearly meet the septum. Thus three passages are formed. The inferior meatus 
is horizontal, lies along the floor half covered by the inferior turbinate, and 
extends from the vestibule to the pharynx. The middle meatus is overhung by THE NOSE. 
665 
the middle turbinate, and is shorter and more oblique than the inferior ; and the 
superior meatus, beneath the superior turbinate, is very short and oblique, and 
ETH.CELLSi 
-ORBIT 
SUPER.. 
TURB. 
SUPR. 
‘MEATUS 
I MEATUS 
MID. 
TURB.‘ 
INFER.— 
TURB. 
■IIMF. MEATUS 
Fig. 712.—Coronal section of nasal fossae at the plane of the second molar tooth, seen from behind. (Hirsch- 
feld.) 
CEREBELLUM 
VESTIBULE- 
HYOID/ 
Fig. 713.—Sagittal section of face and neck, showing external wall of right nasal fossa. (Testut.) 
confined to the supero-posterior angle of the fossa. Above the superior turbinate 
and between it and the sphenoid is an angular recess called the spheno-ethmoidal 
recess. 666 
THE ORGANS OF THE SPECIAL SENSES. 
Cavities Opening Into the Nasal Fossae (Fig. 714). 
Various passages open into the nasal fossae. Under cover of the anterior end 
of the inferior turbinate is the inferior opening of the nasal duct. It is guarded by 
a single or sometimes double fold of mucous membrane. In the floor of the nose, 
at the site of the nasopalatine canal, is a funnel-shaped tube of mucous mem- 
brane of varying depth called Stenson’s canal. It is the relic of the communi- 
OPENINGS OF POSTERIOR 
ETHMOIDAL CELLS 
Fig. 714.—External wall of right nasal fossa, parts of the turbinates having been cut away to show the 
orifices of the sinuses which open into the meatuses. (Testut.) 
cation between the nasal and buccal cavities, found in the early foetus and per- 
manent in some animals. Just above this there is sometimes seen on the nasal 
septum a depression leading into a minute canal, which runs backward for a short 
distance. This is the rudimentary organ of Jacobson. Under cover of the ante- 
rior extremity of the middle turbinate is a deep depression ; the hiatus semilunaris 
(“ half-moon gap ”) which leads up to the infundibulum and thus into the frontal 
sinuses. In the bottom of the hiatus semilunaris is the opening of the anterior eth- 
moidal cells, the maxillary antrum communicating with the nose by the same 
aperture, or by a separate opening a little farther back. Above this is the orifice 
of the middle ethmoidal cells. Into the superior meatus the posterior ethmoidal 
cells open by one or two apertures, and the sphenoidal antrum communicates with 
the spheno-ethmoidal recess. 
The Pituitary Membrane (Schneiderian) is the mucous lining of the nose. It 
is inseparably united with the periosteum and perichondrium over which it lies. 
In the nostril it is continuous with the skin. It is prolonged into the maxillary, 
frontal, ethmoidal, and sphenoidal sinuses. By the nasal duct and lachrymal 
canaliculi it is continuous with the conjunctiva, and behind it joins the mucous 
membrane of the pharynx, and communicates by the Eustachian tube with the 
middle ear and mastoid cells. 
The thickness and vascularity of the membrane and the character of its epi- 
thelium vary in different situations. It is thickest and most vascular over the 
turbinates and septum, not so thick on the floor of the nose, and thin and pale in 
the sinuses. The character of the epithelium and the distribution of the nerves 
divide the nose into an upper, olfactory part, comprising the upper turbinate and THE NOSE. 
667 
a corresponding area of the septum, and a lower, respiratory part, from the level 
of the lower border of the upper turbinate downward. The vestibule is lined 
with a continuation of the external skin, which presents a stratified, squamous 
epithelium, with hairs, sebaceous glands, and sweat-glands. The rest of the 
respiratory area of the nose is covered with stratified, ciliated, columnar epi- 
thelium, with goblet cells, on a delicate basement membrane. The tunica propria 
of the mucosa is composed of white fibrous tissue, rich in leucocytes, and tra- 
versed by a wide venous plexus, so that it resembles cavernous tissue. Compound, 
racemose glands open freely on the surface, and between them is much lymphoid 
tissue, sometimes accumulated into nodules, and some plain muscular fibres. The 
various air-cavities (ethmoidal, frontal, etc.) are very sparingly supplied with 
glands, and in them the tunica propria is very thin. 
The mucosa of the olfactory area is yellowish brown in color. Its epithelium 
presents two kinds of cells, namely sustentacular and olfactory. The sustentacular 
cells are columnar in form, possess no cilia, have their nuclei oval and arranged 
in a single row near their embedded extremities, and end in branching processes, 
which fill the spaces between the expanded, nucleated portions of the olfactory 
cells. The olfactory cells are thickly set between those just described. Each cell 
has an expanded portion in the middle enclosing a round nucleus, and from this 
two processes project. A thicker rod-like process extends fonvard toward the 
surface between the sustentacular cells, ending in the frog in a tuft of fine hairs, 
and described by some observers as possessing in man exceedingly short hair-like 
processes. From the proximal end of the nucleated expansion a fine varicose 
filament courses through the tunica propria, and is continuous with a nerve-fibril, 
which joins the plexus formed by the olfactory nerve, and thus ends in arboriza- 
tions in the glomeruli of the olfactory bulb. The nuclei of the olfactory cells 
are situated at various depths, so that the zone of spherical nuclei is of considerable 
thickness. Beneath these and lying directly on a thin basement membrane some 
observers describe a layer of small polygonal cells. The submucous tissue is rich 
in veins, which here also give the mucous membrane almost a cavernous character ; 
and many tubular glands, either simple or only slightly branched, called the glands 
of Bowman, are embedded in the submucous tissue. 
Nerves.—The olfactory region is supplied by the olfactory nerve and by 
branches of the fifth; the respiratory area by branches of the fifth only. The 
fifth nerve forms fine terminal ramifications among the epithelial cells. For the 
further description of these nerves see the section on the peripheral nerves. 
The organ of Jacobson is an accessory olfactory organ, well developed in the 
rabbit, guinea-pig, and some other mammals, but rudimentary in man. It lies, 
as already described, embedded in the cartilage of Jacobson on each side of the 
septal cartilage near the floor. In man sustentacular cells only are found, but no 
true olfactory cells. 
Fesse/s.—Branches of the internal maxillary, ophthalmic, and facial arteries 
supply the mucous membrane. The veins form so marked a plexus in the deeper 
parts of the mucosa as to cause it to resemble cavernous tissue. This is most 
pronounced over the lower turbinate, lower and hind part of the middle, and 
hind end of the upper turbinate, and the lower and hind part of the septum, and 
over the nasal duct. The lymphatics are very numerous. They join the lymph- 
spaces round the olfactory nerve, and thus communicate with the subdural and 
subarachnoid spaces. THE EAR. 
By F. H. GERRISH. 
THE ear is the organ of the sense of hearing. In the animal in Avhich it 
occurs in its simplest form it is merely a sac, lined with a sensitive membrane 
and filled with fluid. Agitation of the medium in which the animal lives causes 
waves in the fluid of the sac, their striking upon the sensitive membrane pro- 
duces a thrill in the nerve, and this, being transmitted to the nerve-centre, is 
there interpreted as sound. 
Next higher in the scale is an ear, which, in addition to the elements above 
named, has minute stony bodies in its cavity. The effect of these particles is to 
heighten the impression which the waves of fluid bearing them produce upon the 
sensitive nerve. 
The human ear is an extremely complicated organ, but the essential part of 
it is constructed on precisely the plan of this primitive ear. The organ consists 
of three portions, named respectively the internal ear, the middle ear, and the 
external ear. Of these only the first, the internal ear, is of indispensable import- 
ance ; the others are merely accessory to it. 
THE INTERNAL EAR OR LABYRINTH. 
The essential part of the internal ear is a sac, lined with a sensitive membrane, 
and filled with a fluid, in which are hard particles. The sac is so very intricate that 
it is called the labyrinth, and, to distinguish it from the bony cavity in which it 
is lodged, the adjective membranous is applied to it. The membranous labyrinth 
is situated in the petrous portion of the temporal bone. It does not completely 
fill the excavation which it occupies, but between it and the surrounding bony 
wall there is a space, which is filled with a fluid, called perilymph (“ the water 
around ”). 
The Membranous Labyrinth (Figs. 715, 717). 
General Description.—The membranous labyrinth is a closed bag of fantastic 
shape, consisting of several segments, which have received distinguishing names. 
At the middle of the series are two sacs, of which the larger and posterior is 
called the utricle, and the smaller and anterior, the saccule. From the utricle 
extend three long loops, the semicircular canals; from the saccule one long, 
coiled process, the canal of the cochlea; and from each of the sacs a minute tube, 
which unites with its fellow, and thus completes the continuity of the labyrinthine 
cavity. The fluid which fills this unbroken series of chambers and tubes is 
called endolymph (“ the water within ”). 
The membranous labyrinth is lined throughout with epithelium, which is 
simple and flattened, except over the areas where the branches of the auditory 
nerve are distributed, and in these places it is especially modified. 
The Utricle.—The utricle is a sac of irregular shape. Upon that part of its 
inner surface to which a branch of the nerve of hearing is distributed is an area, 
called the macula acustiea (“ auditory spot”), in which the wall is thickened, and 
the epithelium peculiarly modified, being changed from flattened into neuro-epithe- 
lium. Some of the cells become conoidal and have upon their free ends each a 
strong, stiff hair; and others, longer than these and resting upon the basement 
668 THE EAR. 
669 
membrane, act as mechanical supports for the hair-cells. Among the cells are 
twined 'many ultimate filaments 
of the auditory nerve. On the 
free surface of the macula is a 
plate of gelatinous material conT 
taining a vast number of crystals 
of carbonate of lime, called otoliths 
(“ ear-stones ”). These, being 
driven by the waves of endolymph 
forcibly against the projecting 
hairlets, produce a much more 
profound impression than would 
the waves, if their impact was 
not thus accentuated. 
ENDOLYMPHATIC CANAL 
CAN ALIS 
REUNIENS 
The Semicircular Canals.— 
From the utricle the three semi- 
/ circular canals are given off. 
They are named from their position the superior, the posterior, and the ex- 
ternal. The superior and posterior extend upward and backward, but the 
planes of their curves are nearly at right 
angles to one another; the external passes 
horizontally outward. Each of these canals 
is dilated at one end into an ampulla (“ a 
wine-jug”). At the other end the superior 
and posterior unite before reaching the 
utricle, and enter it by a commop opening. 
Thus, there are but five apertures in the 
utricle for the three semicircular canals. In 
each ampulla is a marked ridge, the septum 
transversum, due to a thickening of the wall, 
and this is surmounted by thoj crista acustica 
(“auditory crest”), made up of peculiar 
neuro-epithelial cells (Fig. 716). From the 
top of the uppermost of each of these cells 
projects a very long, rigid, hairlike process, 
the series of them spreading out widely like 
an opened fan, and reaching half-way or 
more to the opposite side of the ampulla. 
Below these hair-cells are sustentacular cells, 
which support them on every side; and 
between the cells of both kinds are fila- 
ments of the auditory nerve, which, though 
in contact with the cells, have no con- 
tinuity of tissue with them. 
Fig. 715.—Membranous labyrinth of the right ear, viewed 
from the outer side. (Testut.) 
Fig. 716.—Diagram of auditory epithelium, 
and the mode of termination of the nerves of 
the ampullae. (M. Schultze.) 
The Saccule.—The saccule is much smaller than the utricle, and is situated 
farther forward and a little lower, but very close to it. It has a macula acustica, 
which is so like that of the utricle that it needs no separate description. 
A minute tube, the canalis utriculosaccular is, is prolonged from the utricle, 
and a mate to it is given off from the saccule. The two unite and form the ductus 
endolymphaticus, a long tube, which ends in a bulbous expansion, the saccus 
endolymphoticus. Thus, though the utricle and saccule do not communicate 
directly, their cavities are connected by means of these ducts. From the saccule 
another tube gives a communication witli the canal of the cochlea. 
The Canal of the Cochlea1 (Fig. 718).—The canal of the cochlea (also called 
1 In describing the cochlea, it is a matter of convenience to ignore its actual attitude, and to 
speak as if its summit were upward, its base downward ; and this plan, which is conventional, will be 
followed here. 670 
THE ORGANS OF THE SPECIAL SENSES. 
ductus cochlearis, and scala media, “the middle staircase”) is a tube which, if 
straightened, would measure nearly one inch and a half in length. It communi- 
cates with the saccule through a short, narrow tube, the canalis reunions (“the 
VESTIBULAR BRANCH 
OF AUDITORY NERVE 
Fig. 717.—Saccule, utricle, and semicircular canals, viewed from the mesial side, showing points of 
entrance of the auditory nerve. (Testut.) 
reuniting canal ”). In shape it is prismoid, blunt at each end, tapering from its 
beginning to its apex, and coiled into a spiral. Of its three sides the upper is 
flat, and is made by the thin membrane of Meissner. Its outer wall is somewhat 
CANAL OF 
COCHLEA 
.COCHLEAR NERVE 
AND GANGLION 
Fig. 718.—Cochlea in transverse section. Observe especially the canal of the cochlea, which is a part of 
the membranous labyrinth. (Testut.) 
curved, with its concavity inward. The lower side is flat, and is composed 
mostly of a strong, fibrous sheet, called the basilar membrane, between which and 
the membrane of Reissner the angle is acute. Upon the basilar membrane are THE EAR. 
671 
located the structures which give the canal of the cochlea its peculiar interest. In 
the main these are especially modified epithelial cells, to which the principal 
part of the nerve of hearing is distributed. The greater portion of these cells 
INTERNAL AUDI-# 
TORY CELLS 
INTERNAL 
ROD 
BASILAR MEMBRANE 
Fig. 719.—Organ of Corti. Diagrammatic view of a small portion. (Testut.) 
constitute the organ of Corti (Fig. 719), and the parts of this around which the 
other elements are grouped are the rods of Corti. They are called inner rods and 
outer rods, according as they are nearer to or farther from the acute angle of the 
Fig. 720.—Distribution of the auditory nerve. Semidiagrammatic. (Testut.) 
tube. The bases of these cells are broad, and securely fastened to the basilar 
membrane; their shafts are slender, and their upper ends enlarged, that of the 
inner suggesting the proximal extremity of the ulna, that of the outer looking 
considerably like the head of a swan. The rods of each set constitute a continu- 
ous row from end to end of the canal. The two sets incline toward each other 672 
THE ORGANS OF THE SPECIAL SENSES. 
and meet above, a tunnel thus being formed, to which the name, canal of Corti, 
is given. Certain cells, called basilar, are attached to the bases of the rods on 
the side which presents toward the cavity, and seem to serve as buttresses to 
them. At the inner side of the inner rods is a row of short cells, from the upper 
end of which project stiff cilia, and from these circumstances they are called inner 
hair-cells (internal auditory cells), beneath which are roundish, protoplasmic cells. 
On the farther side of the outer rods are several rows of cells similar to the inner 
hair-cells, and called the outer hair-cells, these being supported by the cells of 
Dexters, which are fusiform and send long processes upward between the hair-cells 
to the surface. Still farther toward the outer side are conoidal cells, the cells of 
Claudius, each row of which is of less height than that toward its inner side, 
until the level of the undifferentiated cells lining the cavity generally is reached. 
Similar, but less numerous, cells of Claudius are arranged next to the inner hair- 
cells. Over the outer hair-cells and some adjacent rows is spread a membranous 
network, the reticular lamina, through which the hairs protrude. At the inner 
side of the internal cells of Claudius is a groove, the sidcus spiralis, running 
parallel with the organ of Corti. From a line near the acute angle of the coch- 
lear canal starts a fold, at first thin, but soon enlarging into a thick pad, which 
stretches out over, and rests upon, the rods and hair-cells. It is called the tec- 
torial (“covering”) membrane. Likeness has been suggested between this mem- 
brane and the gelatinous pads, loaded with otoliths, which cover the maculae 
acusticse of the utricle and the saccule. 
Branches of the auditory nerve (Fig. 720) enter among the structures which 
compose the organ of Corti, some being distributed to the inner hair-cells, while 
others end between the inner rods, and others still cross the canal of Corti and 
go to the outer hair-cells. Endolymph occupies the canal of the cochlea and also 
the canal of Corti and all of the spaces between the cells of the organ of Corti. 
The Osseous Labyrinth (Figs. 721, 722). 
The membranous labyrinth is situated in the petrous portion of the temporal 
bone. The part of the osseous tissue which immediately surrounds it is extremely 
SUPERIOR 
SEMICIRCULAR 
CANAL 
EXTERNAL 
SEMICIRCULAR 
CANALi 
INTERNAL AUDI- 
TORY MEATUS 
POSTERIOR ) 
SEMICIRCULAR r 
CANAL ) 
FEN ESTRAI 
OVALIS 
FENESTRA 
ROTUNDA 
Fig. 721.—Osseous labyrinth, isolated and viewed 
from the outer side. (Testut.) 
Fig. 722.—Osseous labyrinth, isolated and 
viewed from the mesial side. (Testut.) 
dense, forming a rigid, protective shell for it. This is the osseous labyrinth. Its 
shape corresponds in the main to that of the complicated membranous labyrinth. 
But, although it is, as it were, a tunic for the latter, the fit is a very loose one. 
The membranous labyrinth in most parts occupies not more than a third, in places 
only a fifth, of the diameter of the cavity of the osseous labyrinth. The mem- 
branous, however, does not lie free in the cavity of the osseous, but at every 
part of its course is fastened to its containing case, usually as much as a quarter 
of its circumference being thus attached. Where the nerve-bundles enter the 
membranous labyrinth, it is always closely applied to the osseous. The osseous 
labyrinth is lined with periosteum, and where the membranous comes in contact 
with it, bands of fibrous tissue are added, and serve to confine it in place. THE EAR. 
673 
Fibrous trabeculae cross from the membranous labyrinth to the opposite side of the 
osseous in various parts, and assist in the fixation. The free surface of the peri- 
osteum is covered with delicate, flattened cells, developed from fibrous-tissue 
corpuscles. 
The Vestibule.—The central portion of the osseous labyrinth is a chamber of 
sufficient size to give lodgment to the utricle and saccule. It is called the vesti- 
bule. On its outer side is an opening, the fenestra ovalis (“ oval window”), which 
looks into the middle ear; but it is always closed in the recent condition. A 
depression at the front part of the mesial wall, called the fovea hemispherica, 
lodges the saccule ; and another hollow, the fovea hemielliptica, behind and above 
Fig. 723.—Constituent parts of the osseous cochlea—the modiolus, the coiled tube, the spiral lamina- 
isolated in the first three pictures, and combined in the fourth. Diagrammatic. (Testut.) 
the last, holds the upper part of the utricle. Between the two is a ridge, the 
crista vestibuli, which divides below, and encloses a little pit in which lies the 
lower extremity of the canal of the cochlea. Close to this is the opening of the 
aqueductus vestibuli, holding the ductus endolymphaticus. Behind are the five 
apertures of the three semicircular canals. The canals bear a close resemblance 
in shape and direction to those of the membranous labyrinth which they enclose. 
The scala vestibuli of the cochlea begins at a large opening in the front and lower 
part of the vestibule. 
The Bony Cochlea (Figs. 723, 724).—In front of the vestibule the osseous 
labyrinth presents the cochlea, which looks very like a coiled shell, as its name 
Fig. 724.—Osseous cochlea in vertical section. The broken, white lines indicate the position of the basilar 
membrane of the canal of the cochlea. Semidiagrammatic. (Testut.) 
implies. Its base faces inward, forward, and upward, its apex in the opposite 
direction. It is in reality, as in appearance, a tube, gradually diminishing in size 
from base to apex, and twined nearly three times around a central, conical core, 
the modiolus. From the side of the tube nearer the modiolus a thin shelf of 
bone, the lamina spiralis, projects about half way across its lumen. 674 
THE ORGANS OF THE SPECIAL SENSES. 
Like other portions of the osseous labyrinth the cochlea is lined with peri- 
osteum. Upon the upper surface of the bony, spiral lamina, however, the peri- 
osteum is greatly modified, being much thickened, and ending above the free 
border of the lamina in a deeply grooved edge, the sulcus spiralis, already men- 
tioned. This pad of modified periosteum is the limbus (“ border ”). Along the 
free edge of the spiral lamina the basilar membrane of the canal of the cochlea 
is attached, and stretches straight across to the opposite wall, where the peri- 
osteum is very thick and projects to meet it, constituting the spiral ligament. 
The membrane of Reissner is attached to the upper surface of the limbus. Tims 
it is seen that the lamina spiralis and the canal of the cochlea together divide the 
lumen of the bony cochlea into two unequal parts—one, the smaller, above, called 
the scala vestibuli, because it opens into the vestibule ; and the other, and larger 
one, below, called the scala tympani, because its lower end presents at the fenestra 
rotunda (“round window”), where it would be in continuity with the tympanum 
(the drum of the ear), were it not for the complete closure of this window. It is 
now clear why the canal of the cochlea, which is between the scalse vestibuli and 
tympani, is sometimes called the scala media. 
The scalse vestibuli and tympani have communication only by a small opening, 
the helicotrema (“ hole of the coil ”) at the highest point, the cupola, of the cochlea. 
From the scala tympani near its large end a little canal, the aqueductus 
cochlece, gives passage to a little vein into the inferior petrosal sinus near the 
jugular fossa. 
The Auditory Nerve.—The base of the modiolus presents toward the internal 
auditory meatus, from which it receives a large part of the auditory nerve. The 
fibres of the nerve run in the modiolus to the attached edge of the spiral lamina, 
and then through this to its free edge, whence they are distributed to the organ 
of Corti, as previously detailed. The fibres destined for the lower turn of the 
spiral are at the outside of the bundle, those for the apex in the centre. Within 
the lamina the nerves pass through a mass 
of cells, constituting the spiral ganglion. 
As has been already stated, the space 
between the membranous labyrinth and the 
osseous labyrinth is filled with perilymph. 
This space communicates through the sheath 
of the auditory nerve with the subdural and 
subarachnoid spaces, whose fluid is lym- 
phatic in character, like that of all serous 
membranes. Communication has also been 
shown to exist between the cavity of the 
membranous labyrinth and the subdural 
space by means of the saccus endolym- 
phaticus. 
THE MIDDLE EAR OR TYMPANUM. 
The middle ear (Figs. 725, 726) is 
situated at the outer side of the inner ear 
or labyrinth, and between the latter and 
the external ear. It is known as the 
tympanum or drum of the ear, and various 
features of its structure justify the name. 
Like the labyrinth the tympanum is located 
in the petrous portion of the temporal bone. 
It is a fore-and-aft cleft, deep, long, and narrow. Its roof is formed by a rather 
thin plate of bone, which separates its cavity from that of the cranium. Its 
external and internal walls present the greatest expanses of surface, and con- 
verge to its floor, which has hardly any width. The tympanum is lined 
Fig. 725.—Chain of ossicles and their liga- 
ments, seen from the front in a vertical, trans- 
verse section of the tympanum. (Testut.) THE EAR. 
675 
throughout with mucous membrane, which covers every object contained in the 
cavity. 
The outer wall is composed almost entirely of a broad, fibrous sheet, the mem- 
hrana tympani (“ membrane of the drum ”), and the rim of bone to which it is 
attached. The membrana tympani has as its basis a firm layer of white fibrous 
tissue. On its inner side is a lining of mucosa, and on its outer a coat of skin. 
The membrane is moderately tight everywhere except at the very top, where there 
is a small area, which is comparatively flaccid. The membrane is not flat, but 
its centre presents a prominence upon the mesial side. It slopes markedly from 
above downward and inward. 
The inner wall of the tympanum has a very uneven surface. The most 
marked prominence is the tuber cochlece, produced by the protrusion of the first 
turn of the cochlea. Below this is a round hole, the fenestra rotunda, closed by a 
fibrous membrane, but for which communication would be established between 
the tympanum and the scala tympani. The membrane is called the secondary 
membrane of the tympanum—the second head to the drum. At a little higher 
level than the tuber is the fenestra ovalis, also stopped with a fibrous membrane, 
to which is attached an ossicle, presently to be described. Above this oval win- 
dow is a ridge, which shows the situation of the aqueduct of Fallopius, in which 
is the facial nerve. 
At the rear and upper part the tympanum communicates through a large hole 
with a series of irregular and connected cavities in the mastoid portion of the 
temporal bone, the most considerable and the nearest of these being the mastoid 
CAVITY 
EXTERNAL SEMI- 
-CIRCULAR CANAL 
MEM-j 
BRANA / 
INTERNAL 
JUGULAR 
VEIN 
INTERNAL 
CAROTID 
ARTERY 
AQUEDUCT OF FALLOPIUS 
Fig. 726.—Coronal section of the right temporal bone, passing through the Eustachian tube and the mid- 
dle of the tympanum. Both surfaces of the section are shown, the parts being hinged on the line xx. (Testut.) 
antrum, the others being the mastoid cells. These cavities are all lined with 
mucous membrane, continued into them from the tympanum. Lower down on 
the hind surface is a prominence of bone, called from its shape the pyramid, from 
the apex of which projects the tendon of the stapedius muscle. 
In front and below, the tympanum slopes into a long channel, the Eustachian 
tube, the distal end of which opens into the pharynx. Through this tube air is 
admitted to and expelled from the middle ear, and thus atmospheric pressure on 
the inner and outer sides of the membrana tympani is equalized. The tube does 676 
THE ORGANS OF THE SPECIAL SENSES. 
the service to the tympanum that is rendered by the hole in the side of the kind 
of drum which is accounted a musical instrument. 
The Eustachian tube (tuba auditiva) (Fig. 727) is about an inch and a half 
long. It extends downward, forward, and inward, and its lower end presents a 
TENSOR TYMPANI 
INCUS- 
MEMBRANA 
TYMPANI 
•STYLOID 
PROCESS 
PHARYNGEAL OPEN 
ING OF TUBE 
Fig. 727.—Eustachian tube, laid open by a cut in its long axis. (Testut.) 
projecting margin on the lateral wall of the pharynx, close by the inferior meatus 
of the nose. Its upper part is bony, its lower is cartilaginous. It is lined with 
mucous membrane. 
Above and parallel with the Eustachian tube is a bony canal, lodging the 
tensor tympani muscle, whose tendon projects into the tympanic cavity. 
The Ossicles (Fig. 725).—Extending across the tympanum from side to side is 
a chain of three little bones, the ossicula auditus (“ossicles of hearing”). From 
without inward they are the malleus, the incus, and the stapes. The malleus is 
attached to the membrana tympani, the stapes to the membrane of the fenestra 
ovalis, and the incus is between and connects the others, with each of which it 
has a movable articulation. 
The malleus (“hammer”) has a roundish head, which is upward, a constricted 
neck, and a long tapering handle (manubrium), which extends downward and a 
little backward. A long process runs downward and forward from below the 
neck to the Glaserian fissure; and a short process passes outward to the mem- 
brana tympani. 
The incus (“anvil”) presents a body, upon the anterior surface of which is an 
articular area by which it is jointed to the malleus ; a short process, which runs to 
the posterior wall near the opening of the mastoid antrum ; and a conical, long 
process, which extends at first downward and at last mesially, ending in a knob, 
the orbicular process, which articulates with the stapes. 
The stapes (“ stirrup ”) bears a remarkable resemblance to the object from 
which it is named. Its base, the foot-piece, is broad and very nearly fills the 
fenestra ovalis, to whose membrane it is attached. The side-pieces, crura, con- 
verge to the neck, beyond which is the head, cupped on its outer surface, and 
.articulating with the orbicular process of the incus. 
Besides the attachment of the malleus to the membrana tympani and that of THE EAR. 
677 
the stapes to the membrane of the fenestra oval is, ligaments running to different 
parts of the bony walls serve to hold the ossicles in place. 
Muscles of the Tympanum.—Two muscles are connected with the series of 
ossicles, the tensor tympani and the stapedius. 
The tensor tympani (“ tightener of the drum”) (Fig. 727) is principally situ- 
ated in the canal above the Eustachian tube. Its tendon bends outward on 
escaping from the canal, and is inserted into the handle of the malleus near the 
neck. Contraction of the muscle pulls the membrane of the drum inward, and 
thus tightens it. 
The stapedius arises in the cavity of the pyramid, from the apex of which its 
tendon passes forward into the tympanic cavity, and is inserted into the neck of 
the stapes. This muscle rocks the base of the stapes in the fenestra ovalis, and 
thus causes pressure upon the perilymph of the labyrinth. 
The mucous membrane of the tympanum projects from the roof into the cavity 
in several folds, which are very variable in number, form, and size. The epi- 
thelium of the mucosa is partly columnar and ciliated, and for the rest flattened 
and not ciliated. 
Just below the pyramid the chorda tympani nerve enters the middle ear, and 
runs forward across the handle of the malleus to its aperture of exit near the 
Glaserian fissure. Like the other intratympanic structures it is invested with 
mucosa. 
THE EXTERNAL EAR. 
The external ear comprises (1) the external auditory meatus, the tube leading 
from the outer wall of the tympanum to the surface of the head, and (2) the 
auricle or pinna, the flaring body, which projects from the side of the head. 
The External Auditory Meatus (Fig. 728) is about an inch long. It is of 
FENESTRA OVALIS 
CLOSED BY STAPES 
Fig. 728.—Vertical section through the external auditory meatus and tympanum, passing in front of the 
fenestra ovalis. (Testut.) 
greatest diameter near its outer end, and of least near its middle part. Its direc- 
tion varies in different portions. As it is traced inward, it goes at first forward 
and upward, then backward, and finally forward and downward; but its domi- 
nant trend is inward and forward. The tube rises toward the middle of its course, 678 
THE ORGANS OF THE SPECIAL SENSES. 
and beyond this it descends. Its floor is longer than its roof on account of the 
obliquity of the position of the membrana tympani. 
The mesial portion has a basis of bone, its peripheral, one of yellow jibro- 
cartilage, pieced out with fibrous tissue. The flexibility of the latter portion 
renders it practicable to make the meatus nearly straight by pulling the pinna 
(with which it is continuous) upward and backward. 
The meatus is lined throughout with skin. In the cartilaginous part and the 
adjacent portion of the osseous there is a great number of glands, which struct- 
urally are identical with ordinary sweat-glands, only larger; but, instead of 
secreting perspiration, they form cerumen, commonly called “ear-wax”—a substance 
thought to be offensive to insects, and, conse- 
quently, a defence against their intrusion. The 
glands are called ceruminous. Hear the outer 
end of the tube are many short hairs and seba- 
ceous glands. The skin which clothes the mem- 
brana tympani is very delicate, and is free from 
hairs and glands. 
The Pinna (Fig. 729) is of irregularly oval 
shape, and is an abrupt expansion of the meatus. 
Its central portion is shell-like in form, and 
hence is called the concha. Beginning near 
the middle of the concha is a ridge, which runs 
forward and upward to the front margin of the 
pinna, whence it continues around nearly to its 
lowest part, forming a prominent rim, called the 
helix (“ coil ”). The rim of the concha itself 
begins at its front and lower part in a prominent 
tubercle, the antitragus (“ opposite the tragus ”), 
and runs backward, then upward, and lastly forward, dividing at the junction of 
its hind and upper parts into two branches, which enclose a triangular hollow. 
This margin of the concha is the antihelix (“ opposite the helix ”), and the area 
embraced by its division is the fossa of the antihelix. Between the antihelix and 
the helix is the fossa of the helix, overlapped by the incurved lip of the helix. In 
front, between the origins of the helix and antihelix, is a backward projecting 
plate, which covers the orifice of the meatus at a little distance, and is called the 
tragus. The lowest portion of the pinna is a flat, soft, pendulous body, the lobule. 
All portions of the pinna, except the lobule, are composed almost entirely of 
yellow fbro-cartilage, which is continuous with that in the peripheral part of the 
meatus, and clothed with skin. Except upon the convexity of the helix, the 
skin is very thin and closely adherent to the cartilage. The lobule has no carti- 
lage, and is merely a bag of skin, containing areolar and adipose tissues. 
The pinna is attached to the cranium by ligaments which run forward to the 
root of the zygoma and backward to the mastoid process. 
The shape of the pinna is practically the same all through life, changing less 
than that of any other feature; and, as no two ears are exactly alike, the recog- 
nition of this maintenance of the characteristic peculiarities of each individual 
ear has established what is probably the surest method of physical identification. 
Muscles.—Half a dozen muscles, called intrinsic, connect different parts of the 
pinna with one another. But, as they are all rudimentary in man, are, indeed, 
often impossible of demonstration, and never of any practical importance, they 
will receive no further attention. 
fossa of 
antiheux 
•TRAGUS 
antitragus 
Fig. 729.—Eight pinna. (Testut.) 
There are three extrinsic muscles (Fig. 407) which require mention, though 
almost always imperfectly developed and incapable of action. Occasionally, 
however, there is an individual, who possesses in a measure the ancestral capacity 
of moving his ears voluntarily. 
The attollens aurem (“ lifting the ear ”) or auricularis superior, the largest of 
the trio, arises from the lower border of the epicranial fascia, narrows as it THE EAR. 
679 
descends, and is inserted into the mesial surface of the helix and the prominence, 
which is collocated with the fossa of the antihelix. 
The attrahens aurem (“ drawing the ear toward,” i. e., forward) or auricularis 
anterior, the smallest of the group, arises from the epicranial fascia below the 
front part of the preceding muscle, passes backward, and is inserted into the fore 
part of the helix. 
The retrahens aurem (u drawing back the ear”) or auricularis 'posterior, arises 
from the mastoid process of the temporal bone, passes forward, and is inserted 
into the back of the concha. 
The arteries of the pinna are the posterior auricular and the superficial tem- 
poral. The nerves are the great auricular, posterior auricular of the facial, the 
auriculo-temporal of the fifth, and the small occipital. THE EYE. 
W. KEILLER. 
THE eyeball, which is the essential organ of the sense of sight, is a somewhat 
spherical body, occupying the cavity of the orbit, where it lies embedded in 
a mass of fat and loose connective tissue. From the posterior two-thirds of the 
surface of the eye this bed is walled off* by a membrane known as the capsule of 
Tenon (Fig. 730) between which and the globe of the eye there is a lymph-space 
OPTIC NERVE 
-CORNEA 
UPPER 
TARSUS 
CAPSULE _ 
OF TENON 
LOWER 
TARSUS 
Fig. 7Bo.—The right eye in sagittal section, showing the capsule of Tenon. Semidiagrammatic. (Testut.) 
occupied by very loose areolar tissue, the whole forming a pliable socket, within 
which the eye rotates with the utmost freedom. The anterior third is covered 
by the conjunctiva, a mucous membrane reflected onto the globe from the deep 
aspect of both eyelids. The surface of the globe is pierced by numerous vessels 
and nerves, and gives attachment at certain points to the muscles, by which the 
movements of the eyeball are accomplished. 
A lateral view of the eye on the living subject reveals the fact that its sur- 
face is not all uniformly curved. In such a view the anterior, clear portion, 
known as the cornea, will be seen to bulge out appreciably beyond the normal 
curve of the posterior, white, or sclerotic portion. It thus appears that the eye- 
680 THE EYE. 
681 
ball is not strictly a sphere, but is composed of segments of two unequal spheres, 
an anterior, smaller segment (of a smaller sphere), forming about one-sixth of the 
whole, superposed upon a posterior, larger segment (of a larger sphere), forming 
the remaining five-sixths. 
For descriptive purposes certain points and lines in relation to the eyeball 
must be defined. The anterior pole is the centre of the front surface of the cornea ; 
the posterior pole is the centre of the back surface of the sclerotic; a straight line 
joining these poles is the sagittal axis. The equator of the eyeball is a line 
around its surface equally distant at all points from the two poles; its plane 
divides the globe into anterior and posterior hemispheres. The inner side of the 
eye is appropriately termed the nasal side; the outer, the temporal. 
To prevent misconception, it is necessary to say here that, even if its seg- 
mented formation be disregarded, the eyeball is still not a perfect sphere. The 
transverse diameter (about one inch) is the greatest, the antero-posterior slightly 
less, and the vertical the least. It may be added that, in an antero-posterior, 
vertical section of the eyeball, passing through the sagittal axis, the inner or 
nasal division will be slightly smaller than the outer or temporal. 
Anatomically considered, the eye may be regarded as a hollow sphere (Fig. 
731), whose wall is composed of three tunics and whose cavity is filled by three 
refracting media. The three tunics are (1) an outer, fibrous tunic, consisting of 
ANTERIOR 
CHAMBER 
POSTERIOR CHAMBER 
VITREOUS 
VITREOUS 
-CHOROID 
Fig. 731.—The right eye in horizontal section, showing the upper surface of the lower segment. Dia 
grammatic. (Testut.) 
sclerotic and cornea ; (2) a middle, vascular tunic, comprising choroid, ciliary zone, 
and iris ; (3) an inner, nervous tunic, the retina. The three refracting media are 
the aqueous humor in front, the vitreous humor behind, and the lens between the 
two others. Each of these will be considered in turn. 682 
THE ORGANS OF THE SPECIAL SENSES. 
The two parts of the outer, fibrous tunic, though continuous in structure, 
differ much in appearance, the cornea in front being perfectly clear and trans- 
parent, and the sclerotic behind, white and opaque. Both are dense and firm, 
and serve to preserve the form of the eyeball. At their junction all around is a 
wide, shallow depression, the scleral sulcus. 
THE EXTERNAL OR FIBROUS TUNIC. 
The Sclerotic. 
The posterior surface of the sclerotic is pierced by the optic nerve, an eighth 
of an inch internal to the posterior pole. Here the dural sheath of the nerve 
blends with the sclerotic, and the nerve fibres, in many small bundles, enter 
through distinct minute pores. The part of the sclerotic thus perforated is called 
the lamina cribrosa (“sieve-like layer”). Around the optic nerve-entrance, and 
more or less adjacent to it, the sclerotic is pierced by the ciliary nerves, and the 
long and short posterior ciliary arteries ; while, farther toward the equator, four 
or five apertures transmit the large veins called from their mode of formation the 
vence vorticosce (Fig. 732). A little way (y inch) behind the corneo-scleral junc- 
tion the sclerotic is pierced by the anterior ciliary arteries. Somewhat anterior to 
the equator it gives attachment to the four recti muscles, the two obliqui being 
attached behind. 
On the deep surface of the sclerotic, between it and the choroid, there is a 
layer of loose, pigmented connective tissue, the lamina fusca (“brown layer”), 
which imparts to its inner surface a dingy, brownish hue. This tissue really 
occupies a lymph-space between the two tunics. Thus the sclerotic has a lymph- 
space on each side of it, and the surface that looks toward each space is covered 
by epithelium. 
The sclerotic consists of bundles of connective tissue, containing elastic fibres, 
and having connective-tissue corpuscles lodged in cell spaces. The tissue is dis- 
posed in laminae, in some of which the fibers run longitudinally and in others 
transversely. The laminae are not separable owing to a frequent interchange of 
fibres. 
The scant blood-supply of the sclerotic is derived from the short ciliary and 
the anterior ciliary arteries, and its more scant nerve-supply, from the ciliary 
nerves. 
The cornea, devoid of blood-vessels and perfectly transparent, is the window 
which admits light to the interior of the eye. It is set in the sclerotic in much 
the same way as a watchglass is set in its frame. Here the resemblance ends, 
however, for the sclerotic and cornea are perfectly continuous. Viewed from 
behind, the cornea is perfectly circular, but a front view shows its transverse 
slightly greater than its vertical measurement. This is due to the sclerotic’s over- 
lapping it more above and below than laterally. The cornea is always more 
curved than the sclerotic, but its curvature varies in different individuals and at 
different periods of life, being greatest in youth and diminished in old age. Its 
outer surface is covered by conjunctival epithelium of the stratified flattened 
variety, several cells deep. Its posterior surface is lined by a firm, elastic, 
homogeneous membrane, the membrane of Descend, structurally distinct from its 
own proper substance. Shreds of this membrane stripped off of the cornea tend 
to curl up with the attached surface inward. Around the margin of the cornea 
the membrane of Descemet becomes fibrillar, and breaks up into bundles, some of 
which attach themselves to the sclerotic and choroid, while others bridge over the 
irido-corneal angle, and attach themselves to the front of the iris. These latter 
constitute the ligamentum pectinatum iridis (“the combed ligament of the iris”) 
or pillars of the iris. The sponge-like formation, produced around its border 
The Cornea. THE EYE. 
683 
by the breaking up of the membrane of Descemet, contains a number of minute 
spaces, the spaces of Fontana, which communicate with the aqueous chamber on 
the one hand, and, on the other, with a minute venous sinus contained in a canal 
in the sclerotic, which encircles the margin of the cornea. This is the canal of 
Schlemm. 
The substantia propria of the cornea is composed of many superposed layers 
of connective tissue, the fibres of contiguous layers having different directions, 
and all being inseparably held together, as in the sclerotic, by many interchanges 
of fibres. Between the layers, and even between the bundles and fibrils of which 
they are composed, there is an interstitial cement substance, in which are found 
lymph-spaces, occupied, but not filled, by the corneal corpuscles, and all directly 
or indirectly communicating so as to provide for a very complete lymph-vascular 
circulation. 
Unlike the sclerotic, the cornea is richly supplied with nerves, which are 
derived from the ciliary. They first form a plexus around its margin; then, 
losing their medullary sheath, they form another plexus in the laminated struct- 
ure ; from this branches proceed to form a third plexus on the corneal surface 
beneath the conjunctival epithelium ; finally, fibrils pass in among the epithelial 
cells, and reach their terminal distribution almost at the free surface of the con- 
junctiva. 
THE MIDDLE OR VASCULAR TUNIC. 
In the vascular tunic, or uveal tract, of the eye (Fig. 732) three parts may be 
distinguished : the choroid behind, the iris in front, and the ciliary zone, or body, 
.IRIS 
( ANTERIOR 
CILIARY 
I ARTERY 
SCLEROTIC 
VENA 
VORTICOSA* 
OPTIC 
NERVE 
SHORT 
POSTERIOR 
CILIARY 
ARTERIES 
LONG POSTERIOR 
CILIARY ARTERY 
Fig. 732.—Vessels and nerves of the choroid and iris, seen from above. The sclerotic and cornea have been 
largely removed. (Testut.) 
between. The choroid and ciliary zone are applied to the inner surface of the 
sclerotic ; but, except at the optic nerve entrance and the attachment of the ciliary 684 
THE ORGANS OF THE SPECIAL SENSES. 
muscle to the sclerotic, the adhesion between them is very loose, a lymph-space, 
as already stated, being left between them. The iris, attached only at its circum- 
ference, hangs vertically in the aqueous humor about Ttg- inch behind the cornea, 
its pupillary margin resting lightly against the lens. The choroid is pierced 
behind by the optic nerve. On its outer surface the ciliary nerves, about fifteen 
in number, and the two long posterior ciliary arteries, after piercing the sclerotic, 
run forward to the iris. 
The Choroid. 
The choroid is a dark brown structure, w7hose stroma consists of blood-vessels, 
held together by delicate connective tissue, containing pigmented cells. The 
stroma is limited on both surfaces by non-vascular membranes, the pigmented 
membrana suprachoroidea on the outside, and the unpigmented vitreous lamina on 
the inside. The vessels of the stroma exhibit two well-marked layers, a super- 
ficial venous layer formed of the vasa vorticosa, and a deep, closely-packed, capil- 
lary layer, the chorio-capillaris. Between these layers the short ciliary arteries 
run forward, giving off as they go the vessels of the chorio-capillaris and 
terminating in those of the ciliary processes. 
The Ciliary Zone. 
The ciliary zone or ciliary body differs from the choroid, not so much in the 
composition of its vascular stroma, as in the fact that it contains a deposit of 
muscle-tissue, the ciliary muscle (Fig. 733), and presents on its deep surface a 
LYM PH 
SPACE 
SCLEROTIC*- 
ANTERIOR 
CILIARY VEIN 
RADIATING PART OF 
- CILIARY MUSCLE 
AREOLA R__ 
TISSUE 
PART OF 
CILIARY MUSCLE 
CONJUNCTIVA— 
CILIARY 
PROCESS 
CORNEA- 
Fig. 733.—Meridian section of the eye in the region of the ciliary muscle. (Testut.) THE EYE. 
685 
series of radial thickenings or ridges, the ciliary processes (Fig. 735), about seventy 
in number, which, rising gradually from the anterior limit of the choroid, reach 
their greatest elevation a little behind the corneo-scleral junction, where they 
terminate abruptly in a series of prominences, the corona ciliaris. Superficial to 
these lies the ciliary muscle, containing both radiating and circular fibres. The 
former arise from the deep surface of the sclerotic near the cornea, where they 
are attached to the bundles of the membrane of Descemet already referred to. 
Extending backward they are inserted into the outer surface of the ciliary body 
and choroid. The circular fibres are placed on the deep surface of the radiating 
portion, and form a muscular ring around the circumference of the iris. When 
the ciliary muscle contracts, it draws forward the choroid and ciliary body, thus 
relaxing the suspensory ligament, which allows the lens to become more convex 
for near accommodation. 
The Iris (Figs. 734, 735). 
The iris is the colored membrane, which hangs like a screen in the aqueous 
chamber behind the cornea. In its centre is the aperture called the pupil, 
which, through the contractile power of the iris, varies in size and is thus adapted 
to regulate the amount of light admitted to the retina. At its circumference the 
iris is continuous with the ciliary body, and, through the ligamentum pectinatum 
iridis, with the cornea also. Faint, wavy lines on its anterior surface, converging 
ANTERIOR CILIARY ARTERIES 
CHOROID 
[long CILIARY 
i ARTERY 
ANTERIOR CILIARY ARTERIES 
Fig. 734.—Iris, front view. (Testut.) 
toward the pupil, mark the situation of subjacent blood-vessels. Its posterior 
surface is covered by a layer of dark pigmented epithelium, which belongs 
morphologically to the retina. Its stroma is formed of delicate connective tissue, 
containing a variable number of pigmented cells, and carrying numerous vessels 
and nerves. The color of the iris depends partly on the pigment cells of the 
stroma, and partly on the retinal layer behind. When the pigment is abundant 
in the stromal cells, it controls the color,—some shade of gray, brown, or black; 
but when it is scanty or absent, that of the retinal cells behind showing through 
the stroma imparts to the iris one of the various shades of blue. 686 
THE ORGANS OF THE SPECIAL SENSES. 
Near the pupillary border of the iris there lies embedded in the stroma a cir- 
cular band of smooth muscle-fibres, the sphincter iridis, whose action contracts 
the pupil. On the deep surface of the sphinc- 
ter is a membrane formed of straight fibres, 
stretching from the circumference of the iris 
to the sphincter. Whether these are muscle- 
fibres or merely elastic is still unsettled, but 
the view prevails that they cause dilatation 
of the pupil. 
Vessels and Nerves of the Iris.—The two 
long ciliary arteries run forward along the 
outer and inner aspects of the globe, between 
the sclerotic and choroid, to the attached 
border of the iris. Here each divides into a 
superior and an inferior branch, which, by anas- 
tomosing with one another and with the an- 
terior ciliary arteries (from the muscular 
branches of the ophthalmic), form a vascular 
ring in this situation, the circuius major iridis. 
From this branches are given off, which con- 
verge toward the pupil, where, by dividing 
and anastomosing, they form the circulus 
minor iridis. The arrangement of the veins 
corresponds to that of the arteries. They 
communicate with the sinus in the canal of 
Schlemm. 
The ciliary nerves, after furnishing a gang- 
lia ted plexus to the vessels of the choroid, 
enter the ciliary muscle, where they form 
another plexus. From this latter filaments 
pass into the iris, where they follow the course 
of the blood-vessels, finally ending in the 
sphincter iridis. 
PUPIL 
RADIATING 
VESSELS 
OF IRIS 
_ CILIARY 
"process 
Fig. 735.—Segment of the iris, ciliary 
body, and choroid, view from the internal 
surface. (Testut.) 
THE INNER OR NERVOUS TUNIC 
The Retina (Fig. 736) constitutes the innermost coat of the ocular wall. It 
is everywhere in close contact with the uveal tunic. Developmentally it is laid 
UPPER TEMPORAL BRANCH 
OF ART. C£NTR. RET. 
SCLEROTIC 
< CHOROID 
.RETINA 
UPPER NASAL 
-- BRANCH OF 
ART. CENTR. RET. 
TEMPORAL SIDE 
NASAL SIDE 
Fig. 736.—Retina of the right eye, front view. The macula lutea is seen in the middle, and the porus 
opticus at the right of it. (Testut.) THE EYE. 
687 
clown in two strata, an outer pigmented stratum, which lines the inner surface of 
the middle coat, and an inner stratum, which differs in different parts. 
Beneath the choroid is the retina proper, the part directly engaged in vision. 
It reaches from the optic entrance to the outer or posterior limit of the ciliary 
zone, where it terminates in an indented border, the ora serrata. Beyond this 
the inner stratum exists as a single layer of unpigmented, columnar epithelium, 
with no admixture of nerve-fibres, and is called the pars dliaris retina. It 
reaches to and over the tips of the ciliary processes, whence it is continued as a 
pigmented layer, pars iridica retina, to the pupillary border of the iris. Here 
it doubles outward upon itself and becomes continuous with the outer pigmentary 
stratum. Thus there is on the hind surface of the iris a double layer of pig- 
mented epithelium, belonging developmentally to the retina. 
The inner surface of the retina proper rests upon the vitreous body. In its 
centre, and hence in the axis of the eyeball, is the macula lutea or yellow spot, the 
point of acutest vision. The fovea centralis is the name given to a dimple or 
depression in the middle of the macula lutea. About i inch to the nasal side of 
the yellow spot is the pale disc of the porus opticus (“optic passage”). Here 
the optic nerve appears through the retina, and spreads out to form its innermost 
layer. From the centre of the porus opticus the arteria centralis retina emerges, 
dividing into an upper and a lower branch. These again divide and subdivide 
dichotomously giving offsets to the retina till they reach the ora serrata. Their 
ramifications anastomose neither with one another nor with any other vessels. 
The corresponding veins converge toward the porus opticus, where they enter the 
optic nerve in two divisions, which soon unite. Retinal vessels are absent near 
the macula lutea. 
All these objects, but not the retina itself, are visible in an ophthalmoscopic view 
of the fundus of the eye. The veins appear darker and larger than the arteries. 
The general, red reflex which pervades the interior comes from the vessels of the 
chorio-capillaris. 
The retina is a very complex membrane, consisting of several layers of nerve- 
cells, and specialized nerve-epithelium, all held together by sustentacular fibres 
(of Muller), which pass vertically through the layers from the inner almost to the 
outer surface. 
The limits of this book preclude a detailed account of the structure of this 
interesting organ, but some idea of its complexity may be gathered from Fig. 737. 
What is definitely known and what may usefully be introduced here are embraced 
in the following statements : 
1. The layer of rods and cones and the overlying pigmented cells are the only 
parts molecularly affected by light. 
2, Except between the nerve-fibres of the innermost layer and the nerve- 
cells of the adjacent layer, there is no direct anatomical continuity between the 
elements of the different strata. An apparent exception occurs in the case of 
the outer nuclear layer; but it is only apparent, for here the granules are not 
separate elements, but swellings on the axis-eylinder processes of the rods and 
cones. 
3. The retina with the optic nerve may practically be regarded as a nerve 
chain of three links establishing connection between the rods and cones (the 
special sensory cells of the retina) and the brain cells, from which the fibres of 
the optic nerve come off. These links are— 
(l) The rods and cones with their axis-cylinders (including the outer gran- 
ules). 
(2) The bipolar cells of the inner nuclear layer with their axis-cylinders. 
(3) The ganglionic nerve-cells and the optic nerve-fibres which, as before 
intimated, are in direct anatomical continuity. 
4. The two molecular layers mark the situations at which connections are 
made between these nerve links. Thus, in the outer molecular layer the axis- 
cylinders of the rods and cones connect by arborization and interlacement with 688 
THE ORGANS OF THE SPECIAL SENSES. 
processes from the cells of the inner nuclear layer. In the inner molecular 
layer the processes from the opposite ends of the same cells connect similarly 
with those from the ganglionic cells. These being in direct continuity with the 
fibres of the optic nerve, are thus connected with cells of the visual centres in 
the brain. 
5. The internal and external limiting membranes mark the inner and outer 
limits of the sustentacular fibres. They are not separate or independent struct- 
ures, and the external, at least, is more imaginary than real as a membrane. 
The internal membrane is formed by contact of the expanded bases of the fibres 
of Muller. 
6. All the layers become extremely thin over the fovea centralis, both the 
CHOROID 
PIGMENTARY 
LAYER 
LAYER OF RODS 
AND CONES 
EXTERNAL LIMITING 
LAYER 
NEURO-EPITHELIALy 
PORTION N 
EXTERNAL NUCLEAR 
OR GRANULAR LAYER 
OUTER MOLECULAR 
LAYER . 
INTERNAL NUCLEAR 
DR GRANULAR LAYER 
INNER 
MOLECULAR 
LAYER 
CEREBRAL, 
PORTION 
LAYER OF 
NERVE CELLS 
LAYER OF 
NERVE FIBRES 
INTERNAL LIMIT- 
ING LAYER 
Fig. 737.—Section of retina, showing its layers. The fibres of Muller are in red. Diagrammatic. (Schultze.) 
VITREOUS 
layer of nerve-fibres on the inside and the rods on the outside being completely 
wanting. Around the border of the fovea they rapidly thicken, however, and 
over the rest of the macula lutea are thicker than anywhere else in the retina. 
At the ora serrata all the layers disappear abruptly, and only the layer of colum- 
nar epithelium before referred to takes their place in the pars ciliaris retinae. THE EYE. 
689 
THE MEDIA. 
As already stated, the vitreous body, the lens, and the aqueous humor com- 
pletely fill the cavity of the eyeball. The aqueous is perfectly fluid, the vitreous 
semi-fluid, and the lens solid. All are transparent and colorless. 
THE VITREOUS. 
The vitreous (“glassy”), also called “vitreous humor” and “vitreous body” 
(Fig. 731), fills the posterior four-fifths of the globe. It is enclosed in a thin, 
hyaloid membrane, which has some attachment to the retina at the porus opticus, 
and furnishes a suspensory ligament to the lens. Elsewhere it is perfectly 
separable from its surroundings. Through the centre of the vitreous body a 
canal, lined by a tube of the hyaloid membrane, runs from the porus opticus to 
the back of the lens, where it ends blindly. It marks the course of a vessel, 
which, in the foetus, passed from the central artery of the retina to the capsule of 
the lens. It is known as the canal of Stilling. Beyond the ora serrata the sur- 
face of the vitreous body is grooved by the ciliary processes, while, anteriorly, 
it presents a deep concavity, the fossa jpatellaris, for the posterior convexity of 
the lens. 
Subjacent to the ciliary zone the hyaloid becomes thick and fibrous, and 
adheres closely to the pars ciliaris retinae. Here it splits, giving off from its 
under surface the true hyaloid, which is continued over the fossa patellaris, while 
the outer fibrous portion, the zonula of Zinn, stretches inward and forward as a 
distinct membrane to gain attachment to the capsule of the lens a little in front 
of its equator. Some scattered bundles from the zonula are attached at the 
equator and some on the posterior surface also. The free portion of the zonula 
between the ciliary processes and the lens-capsule constitutes the suspensory liga- 
ment of the lens. A space around the circumference of the lens, bounded by the 
suspensory ligament in front and by the vitreous (covered by hyaloid) behind, is 
the canal of Petit. It is filled with fluid, which may reach it from the aqueous 
chamber through extremely fine clefts, which have been demonstrated in the 
suspensory ligament. 
THE LENS. 
The lens (Fig. 731) is a biconvex body occupying the fossa patellaris in front 
of the vitreous. Its anterior surface looks toward the aqueous chamber, and is 
in light contact with the pupillary margin of the iris. The circumference or 
equator all round looks toward the ciliary processes. In this position the lens is 
safely anchored by the suspensory ligament already described. 
The posterior surface is considerably more curved than the anterior, and the 
curvature of each varies with the period of life. In the foetus, the lens is almost 
spherical; in the adult, of medium convexity; and in the aged, considerably 
flattened. Besides this the curvature is constantly changing for near or distant 
accommodation. 
The lens is inclosed in a structureless, elastic, non-vascular capsule, which is 
much thicker in front than behind. When ruptured or cut through, this mem- 
brane shows a tendency to curl outward away from the lens. The lenticular sub- 
stance immediately beneath the capsule is soft and gelatinous, but deeper it 
becomes hard and firm. The central hard core is sometimes called the nucleus of 
the lens, while the outer soft part is known as the cortex. 
THE AQUEOUS. 
The aqueous humor is a watery fluid, occupying the space which is bounded by 
the cornea in front and by the lens, suspensory ligament and ciliary body behind. 
This space is known as the aqueous chamber (Fig. 731). The iris partially divides 690 
THE ORGANS OF TFIE SPECIAL SENSES. 
it into an anterior and a posterior chamber, which, however, are continuous through 
the pupil. The aqueous humor is thought to be secreted in the posterior chamber, 
whence it finds its way through the pupil into the anterior chamber. From this 
it is drained away through the spaces of Fontana into the canal of Schlemm, 
Although the vitreous, the aqueous, and the lens are commonly spoken of as 
the “ refracting media ” of the eye, it should be understood that of the three the 
lens alone has any considerable effect in changing the direction of the rays of 
light, which enter the eye, and furthermore, that the cornea, often referred to as 
if it had an indifferent influence in this regard, is really very powerfully refrac- 
tive. 
THE MUSCLES OF THE EYEBALL. 
There are seven muscles (Fig. 738) in the cavity of the orbit, but only six are 
attached to the eyeball. These are arranged in three opposing pairs, viz., the supe- 
rior and inferior recti, the internal and external recti, and the superior and inferior 
obliqui. All except the inferior oblique arise from the immediate vicinity of the 
optic foramen, either from the bone-surface or from an aponeurotic ring, the liga- 
ment of Zinn, which is attached around the upper, inner, and lower edges of the 
foramen, and bridges over the sphenoidal fissure. The external rectus is attached 
to this latter part, as well as to the bones on each side of the fissure. Hence the 
( PALPEBRAL TENDON 
. OF LEVATOR PALPE- 
I BR/E EVERTED 
ORIGIN OF LEVA 
TOR PALPEBR/E 
OPTIC NERVE 
Fig.73B—Muscles of right eye, viewed from above. (Testut.) 
two heads, from which it is said to arise, are really continuous. The superior 
rectus has some attachment to bone above the foramen and to the sheath of the 
optic nerve, as well as to the aponeurotic ring referred to. The superior oblique 
arises wholly from bone beyond the ring and above the inner edge of the foramen. 
Diverging as they come forward, the four recti go straight to their insertions 
into the sclerotic in front of the equator, and on the aspects of the eyeball cor- 
responding to their names. The superior oblique courses upward, inward, and 
forward to the supero-internal angle of the orbit, where it passes through a fibro- THE EYE. 
691 
cartilaginous loop or pulley, attached to the orbital surface of the internal angular 
process of the frontal bone. It then bends back at an acute angle, and passes 
downward, backward, and outward beneath the superior rectus to its insertion in 
the sclerotic behind the equator, between the superior and external recti. 
The inferior oblique arises from the orbital plate of the superior maxilla just 
outside the lower end of the lachrymal groove, whence it passes backward and 
outward beneath the inferior rectus (1. e., between it and the orbital floor); then, 
turning slightly upward, it reaches its insertion into the sclerotic between the 
optic entrance and the attachment of the external rectus. 
Action,—These muscles rotate the eye in different directions, but without 
changing its position in the orbit. , Omitting refinements for the present, it may 
be stated that the superior and inferior recti rotate the eyeball on a transverse 
axis, thus raising and depressing the cornea ; the internal and external recti rotate 
it on a vertical axis, thus turning the cornea inward and outward, i. e., adducting 
and abducting it; and the superior and inferior obliques rotate it on a sagittal 
axis, thus turning the cornea round like a. wheel on its axis. 
Besides its main action, the superior rectus adducts and slightly rotates the 
cornea inward, and to correct this tendency is the special function of the inferior 
oblique. Again, the inferior rectus in addition to its main action, tends to adduct 
the cornea and rotate it outward ; but the superior oblique opposes both these 
tendencies. What has been described as their main actions are the sole actions 
of the two lateral recti. 
The levator palpebrce superioris (“lifter of the upper lid”) may appropriately 
be described in this connection. It arises from the small wing of the sphenoid 
above the origin of the superior rectus, and passing forward close to the roof of 
the orbit, is inserted by a broad aponeurosis into the tarsus of the upper lid. It 
also sends a more superficial fibrous expansion forward among the fasciculi of the 
orbicularis palpebrarum, and this gains an attachment to the skin of the eyelid. 
Its action is to elevate the lid. 
Nerve-supply.—The superior oblique is supplied by the fourth cranial nerve, 
the external rectus by the sixth, and all the rest by the third in two divisions. 
The superior division is given to the levator palpebrae and superior rectus; the 
inferior to the inferior and internal recti and the inferior oblique. 
Under this head come the eyelids, conjunctiva, and lachrymal apparatus. 
THE SUPERFICIAL APPENDAGES OF THE EYE. 
The Eyelids. 
The eyelids (palpebrce,) are two loose, tegumentary folds, which when brought 
together, cover the front of the eyeball. The upper is larger and more movable 
than the lower, and takes by far the greater part in opening and closing the eye. 
About half an inch above its free margin a transverse wrinkle, the superior 
palpebral fold, divides it into an upper or orbital portion and a lower or palpebral 
portion. Over the former part the skin is extremely loose, and lends itself 
readily to subcutaneous hemorrhage and conditions of oedema. Over the lower 
part it is closely adherent to the subjacent tissue. There is an inferior palpebral 
fold in the skin of the lower lid, but it is not as well marked, unless the eye is 
widely open. The space between the free margins of the lids, the palpebral 
aperture, varies a good deal in different individuals, and even in the same 
individual according as the pupil is directed upward, downward, or straight for- 
ward. In the first position the space is greatest, in the second, least. The angles 
formed by the lids at their inner and outer ends are called the canthi, of which 
the outer is sharp, the inner rounded. The free margins of the lids are fiat, and 
present an anterior rounded angle and a sharp posterior one in contact with the 
eyeball. Along the anterior angle project two or three rows of short, strong 692 
THE ORGANS OF THE SPECIAL SENSES. 
hairs, the cilia or eyelashes, which curve away from the palpebral aperture. 
Behind these and nearer to the posterior angle are the openings of the ducts of 
the Meibomian glands, twenty or thirty in number and more numerous in the 
.SUPRAORBITAL VES- 
SELS AND NERVE 
LACHRYMAL ARTERY 
AND NERVE 
LACHRYMAL SAC 
EXTERNAL LATERAL* 
LIGAMENT 
JNTERNAL LATE- 
RAL LIGAMENT 
Fig. 739.—The tarsi and their ligaments—right eye, front view. (Testut.) 
upper lid than in the lower. There are also modified sweat and sebaceous glands 
in this situation. 
For the first fifth inch out from the inner canthus the divergence of the lids 
is very gradual and then suddenly becomes more marked. Along this part the 
lids have no cilia and are not in contact with the eyeball. Nestling in between 
them in this situation, and resting against the globe of the eye, is a little fleshy 
protuberance, the caruncula lachrymalis (“ the little fleshy body pertaining to 
tears”), which has all the characteristics of true skin, although quite isolated 
from the adjacent integument. The depression here between the lids, from the 
bottom of which the caruncle protrudes, is known as the lacus lachrymalis (“ lake 
of tears ”). 
Just at the points where the divergence of the lids becomes suddenly more 
pronounced a small prominence may be noticed on the margin of each lid. This 
is the papilla lachrymalis, and on its summit is the minute opening, punctum 
lachrymale of the lachrymal canal, leading into the lachrymal sac. The lower 
punctum is slightly farther out than the upper. The puncta are applied to the 
surface of the globe and are not seen unless the lids are slightly everted. 
Structure of the Eyelids (Fig. 740).—On their superficial aspect the eyelids 
have a covering of skin, very thin and delicate, and containing fine hairs, 
sebaceous follicles, and sweat glands. On their posterior surface they are 
covered by a mucous membrane, called the conjunctiva, which, at a certain distance 
back from the free margin, is reflected onto the eyeball. Between these two 
coverings various other structures enter into the formation of the lid. Imme- 
diately beneath the skin is a layer of loose, fatless, areolar tissue, which provides 
for the laxity of the integument. Embedded in this tissue is the orbicularis 
palpebrarum muscle, the sphincter of the palpebral aperture, serving by its con- 
traction to approximate the lids, and thus close the eye. Deeper than this is the 
tarsus (often, though improperly, called “tarsal cartilage”) (Fig. 739), a thin 
plate of dense, fibrous tissue devoid of cartilage cells, which strengthens the 
margin of the lid, and stretches from the inner to the outer orbital wall. The 
upper tarsus is much stronger and thicker than the lower, and about twice as 
wide. Each tarsus is thickest at its free border and widest in the middle. They 
thin off toward the attached edges above and below, and taper toward the ends. 
Their attachments to the inner and outer orbital margins are known as the inner THE EYE. 
693 
and outer 'palpebral ligaments. The former, which is much the stronger and more 
marked, is often called the tendo oculi. It is attached to the nasal process of the 
superior maxilla in front of the lachrymal groove, and to the ridge on the 
lachrymal bone. Between these points it arches round the front and outer walls 
of the lachrymal sac. Where the two tarsi blend into this ligament it gives origin 
to the palpebral portion of the orbicularis muscle, and when this muscle contracts, 
closing the lids, it produces an enlargement of the cavity of the lachrymal sac 
thus causing it to suck in the tears from the lacus lachrymalis. To the upper edge 
-UPPER MARGIN OF ORBIT 
ADIPOSE TISSUE 
.evator palpebr;e 
SU PER lORIS 
MUSCULAR TENDON 
OF LEVATOR 
FORNIX OF CON- 
JUNCTIVA 
SKIN- 
AREOLAR. 
TISSUE 
ORBICULARIS^ 
PALPEBRARUM 
-AREOLAR TISSUE 
DOWNY 
HAIR 
CONJUNCTIVA 
MEIBOMIAN GLANDS 
SWEAT, 
GLAND 
TARSUS 
Fig. 740.—Upper lid in sagittal section. (After Merkel.) 
CILIAL 
I GLAND OF MOLL 
of the superior tarsus is attached the wide tendon of the levator palpebrse, and 
to the lower edge of the inferior tarsus a fibrous expansion from the sheath of 
the inferior rectus. Embedded in the deep surface of each tarsus are the 
Meibomian glands, longer and more numerous in the upper lid than in the lower. 
On everting the eyelid they may be noticed as faint pearly lines running beneath 
the conjunctiva toward the free margin of the lid. They are a variety of 
sebaceous glands and their secretion prevents any adhesion between the lids, and 
keeps the tears from flowing over onto the face until considerably heaped up in 
the palpebral aperture. 
The Conjunctiva (Fig. 741). 
The conjunctiva is a mucous membrane, which, as before stated, lines the inner 
surface of the eyelids (palpebral conjunctiva) and is reflected from them onto the 
surface of the eyeball (ocular conjunctiva). The fold of reflection is the con- 694 
THE ORGANS OF THE SPECIAL SENSES. 
junctival fornix. It is deeper in the upper than in the lower lid. To that part of 
the lid to which the skin is closely adherent on the outside the conjunctiva is equally 
adherent on the inside. Over the rest of the lid, and 
over the eyeball as far as the cornea it is comparatively 
loose. On the cornea it adheres firmly. The palpebral 
conjunctiva is thick, vascular, and highly sensitive. On 
the sclerotic the ocular conjunctiva becomes thin and 
transparent, and in the healthy condition is only slightly 
vascular. On the cornea it becomes reduced to a layer 
of stratified, flattened epithelium, several cells deep. 
Just outside the caruncula lachrymalis there is a 
semilunar fold of conjunctiva stretching between the lids 
with its concavity toward the cornea. This is the plica 
semilunaris, the rudimentary homologue of the mem- 
brana nictitans, or third eyelid, in birds. 
-SUPERIOR FORNIX 
''INFERIOR FORNIX 
of cyeT showing^upeVioroand0and 
junctivafol(Tesetut0)f the coa' 
The Lachrymal Gland (Fig, 742) 
This organ is situated in the upper, outer, and anterior part of the orbital 
cavity, occupying a fossa in the orbital plate of the frontal bone at the inner side 
of the external angular process. It rests upon the upper and outer aspect of the 
eyeball (separated from it by conjunctiva) between the attachments of the superior 
and external recti. It consists of two portions, partially separated by a fibrous 
septum, an upper, larger part 
lying against the orbital roof, 
and a smaller, lower part, which 
reaches forward almost to the 
margin of the orbit, and outward 
as far as the external canthus. 
The ducts of the gland, seven or 
eight in number, open in a row 
on the upper and outer part of 
the palpebral conjunctiva near 
the fornix. The progressive 
closure from without inward of 
of the lids in winking disperses 
the lachrymal secretion over the 
whole surface of the eye, and 
tends to collect it in the lacus 
lachrymalis. Here it is sucked 
into the lachrymal canals through 
the puncta, which are applied 
closely to the surface of the eye, and is conveyed by them to the lachrymal sac, 
into which they open separately, or by a common tube. From this it is conveyed 
downward through the nasal duct into the inferior meatus of the nose, where it 
helps to moisten the inspired air. 
The lachrymal canals are first vertical in direction in both lids, then horizontal 
and convergent inward—points to be remembered in attempts to pass a probe or 
bristle. The lachrymal sac is the upper enlarged end of the nasal duct. Its 
upper extremity is blind, and reaches higher than the openings of the canals. It 
is lodged in the groove formed by the lachrymal bone and superior maxilla, and 
is continuous below with the nasal duct. Both form a tube of mucous membrane, 
which is continuous with that of the nose below and with the conjunctiva above. 
The bony canal in which this tube lies is lined throughout by periosteum, 
between which and the mucous membrane there is a layer of loose, connective 
tissue. This is particularly abundant around the lachrymal sac, thus allowing 
considerable distension of that organ. 
CARUNCLE 
CANALICULUS 
LACHRYMAL SAC 
DUCTS OF/' 
LACHRYMAL, 
GLAND I 
NASAL DUCT 
Fig. 742.—The lachrymal apparatus of the right eye. (Tes- 
tut.) THE ORGANS OF DIGESTION. 
By F. H. GERRISH. 
IN the lowest forms of animal life there is no differentiation of organs, each 
part of the body being equally capable of performing every kind of work 
within the sphere of the creature’s possibilities. The little animal called amoeba 
furnishes a good illustration of this fact. The whole creature may be regarded 
as a minute mass of living protoplasm. A particle of nutritious material coming 
in contact with the sensitive surface of an amoeba is seized by little protrusions 
which are thrust out around it, and is presently enclosed completely by the pro- 
longations. In the containing cavity thus formed the particle is held until the 
animal has absorbed all of the food which it can get from this source. Then the 
little projections which have enwrapped the nutrient material are withdrawn, the 
cavity which they formed is thus obliterated, and the residue of the bit of pabu- 
lum is released. Soon, it may be, the very portion of the amoeba, which was 
just now a recess, becomes a protrusion, fastens to some fixed object, and by its 
contractile power pulls the bulk of the animal up to the point of attachment, 
itself becoming effaced in the process. Thus, it will be seen that a single portion 
of the creature’s body can serve as an organ of sensation, an organ of prehension, 
an organ of absorption, and an organ of locomotion : feeling, grasping, abstract- 
ing, moving from place to place are all in turn shown to be capabilities of one 
small part, which in no way differs from every other part. Each of these organs 
was merely temporary : the impact-perceiving surface was transformed into seiz- 
ing hands ; these presently became a stomach; this soon turned into a leg; and 
the leg disappeared by flattening itself out into a sensitive surface, capable of 
appreciating the touch of a particle brought in contact with it. 
Differentiation of Organs.—ln animals a little higher in the scale of being a 
depression is seen at some point of the surface, forming a permanent recess, into 
which minute bits of pabulum are received and de- 
prived of their nourishing material, after which pro- 
cess the unserviceable remnants are expelled by the 
door which gave them admission (Fig. 743). A step 
farther up we find the receptacle deeper, more capaci- 
ous, and capable of effecting such changes in the food 
introduced into it as will make a larger proportion 
available for absorption into the system. In the next 
grade beyond this, the cavity becomes so long as 
nearly to reach the surface opposite to that at which 
its opening is located. One slight additional exten- 
sion in the direction of previous growth results in 
perforation of the tissues intervening between the 
cavity and the surface; and, thus, the deep depres- 
sion is converted into a tube, reaching from one end 
of the animal to the other, and permitting the expul- 
sion of the unused portion of the food by an opening 
other than that by which it was introduced. 
MOUTH, 
-MOUTH 
VENT- 
Fig. 743.—Diagram to illustrate 
the gradual development of the 
alimentary tube. (Testut.) 
This tube, short and simple, is the type upon which is constructed every ali- 
mentary canal, however complicated. Elaboration of this structure is accom- 
695 696 
THE ORGANS OF DIGESTION. 
plished in several directions : (1) by enlargement longitudinally, so that the length 
of the canal becomes in some animals many times greater than that of a straight 
line between its two extremities, thus furnishing an immensely more extensive 
surface, without corresponding increase in the size of the individual; (2) by dila- 
tation at various places, and by the formation of transverse folds projecting into 
the bore, by which is gained not only augmentation of area, but also, what is 
of great advantage, temporary detention of the contents so that they may be 
modified in ways which would be impossible 
during their rapid passage ; (3) by the addi- 
tion of certain structures and materials to the 
walls of the tube, which thus can effect the 
comminution of introduced material, furnish 
solvent fluids of different kinds, and influ- 
ence the acceleration or retardation of the 
current of the matters contained in the 
canal; (4) by the development of acces- 
sory organs, which, though originating as 
mere buds from the sides of the tube, grow 
and develop until they attain considerable 
—perhaps immense—size, and supply secre- 
tions of essential importance; and (5) by 
the formation of a reservoir, in which waste 
matters can be stored until it is convenient 
to void them. 
MOUTH 
GLANDS 
''"PHARYNX 
•GULLET 
LIVER 
STOMACH 
-PANCREAS 
The Human Alimentary System (Fig. 
744).—These features are all illustrated in 
the human alimentary system. The tube 
measures thirty feet from the aperture of 
introduction, the mouth, to the opening of 
expulsion, the vent or anus ; but the dis- 
tance between these points in a direct line 
is not more than the same number of inches. 
Connected with the initial segment of the 
canal is an apparatus, which minces and 
crushes hard masses of aliment, thus pro- 
digiously increasing the surface of the 
matters to be acted upon by the solvent 
fluids, and, consequently, expediting the 
liquefactive process. The lining membrane of the entire tube is of the mucous 
variety; but it does much more, in the greater part of its course, than furnish 
a protective smear, for it is so modified by the formation in its very substance 
of a numberless multitude of peculiar glands, that it affords various juices, by 
whose agency important changes in the preparation of food for absorption are 
brought about. From one end of the canal to the other its walls contain muscle, 
which by its contraction carries the contents onward with sufficient speed. A 
short distance from its beginning the tube expands into a large cavity, the stomach, 
which delays the swallowed food, as a pond in the course of a river causes a dim- 
inution in the rapidity of the current. Throughout the most of the remainder of 
the canal we find little shelves, extending into the lumen from the sides, and causing 
at once increase of surface and retardation of the stream. There are also glands 
—the salivary, the pancreas, the liver—which, although entirely outside of the 
limits of the alimentary tube in their developed condition, originate from it, dis- 
charge their peculiar products into it, and are thus accessory in their action to 
the glands which make a part of the walls of the canal itself. Finally, the last 
great segment is so constructed that it acts as a receptacle in which unappropri- 
ated parts of the food and certain effete substances from the system can be 
retained until the arrival of suitable times for their evacuation. 
large 
INTESTINE 
SMALL/ 
INTESTINE 
and^t^'appeniS^^TTestut)6 alimentary tube 
ANUS THE ORGANS OF DIGESTION. 
697 
Segments of the Alimentary Tube.—The alimentary canal is naturally divided 
into a number of segments, which occur in the following order, beginning at the 
upper end : mouth, pharynx, gullet, stomach, small intestine, large intestine, anal 
canal. It is usual to reckon the anal canal as a part of the large intestine ; but, 
later in this chapter, it will be seen that there is good reason for giving it a place 
as a separate segment, since it should be regarded as a tubular passage rather than 
as a mere opening. 
Tunics of the Alimentary Canal.—Every portion of the inner surface of the 
canal is covered by mucous membrane, with the exception presented by the crowns 
of the teeth. Even this, to the philosophical anatomist, does not seem an excep- 
tion ; for he recalls the fact that the teeth, though so dense and white as to afford 
a very striking contrast to the soft and reddish membrane from which they pro- 
ject, are epithelial in their mode of development, and that the glistening, dry 
enamel, which encrusts their crowns, is strictly and wholly epithelium, originally 
like that which surmounts the dull and moist mucosa. Outside of this inner, 
mucous tunic is one of areolar tissue, almost everywhere very distinct, but, in a 
few places of no great extent, very condensed. Still another coat is found exter- 
nal to the areolar, the muscular, usually arranged in two layers, an internal, 
whose fibres are circular in direction, and an external, in which they run longi- 
tudinally. Finally, in that portion of the canal, which lies below the diaphragm, 
there is almost everywhere a fourth tunic, composed of serous membrane. 
The Service of each Tunic.—Calling; to mind the character and functions of 
these various membranes and tissues, as described in the chapter on histology, we 
shall quickly obtain a general idea of the physiological capabilities of the tube 
whose wall they compose. 
Mucous membrane is a soft, moist structure, secreting a glairy fluid, which 
serves to smear the surface, and thus at once prevents its becoming dry, and pro- 
tects from the injury which the contact of foreign substances might otherwise 
occasion. In the larger part of the alimentary canal the membrane contains 
great numbers of small, tubular glands, which, instead of secreting mucus alone, 
as is the case with the corresponding structures in the respiratory tubes, the 
urinary bladder, and other organs, manufacture different fluids, possessed of such 
qualities that they can effect important changes in food which is taken, and put 
it in condition to undergo absorption into the blood and incorporation into the 
tissues of the body. Mucosa is not an elastic structure :it will bear very little 
stretching without harm. But we find that, where it lines hollow organs, which 
are liable to become distended, it is, at almost every part of the surface, so loose 
in the collapsed condition of the viscus that it is deeply wrinkled, and lies in 
well-marked folds. When the cavity is filled, these loose ridges are smoothed out 
and disappear, and the mucosa is evenly spread, but not rendered tense; and, 
thus, it suffers no harm. 
This passive movement of the membrane would not be practicable except for 
the areolar coat, which connects it with the muscular. Areolar tissue is strong, 
flexible, elastic, and full of spaces in the meshes of its network. It, therefore, 
holds the mucosa firmly but gently in place at all times, regulating its wrinkling 
so that its folds are evenly distributed, and permitting its extension without dis- 
placement from its proper relation to the muscular coat. 
The areolar coat affords an easy and safe bed for the vessels and nerves, 
whose twigs, and rootlets, and filaments form networks throughout the two tunics, 
between which this coat is situated. 
The muscular coat is that by which active movements of the tube are pro- 
duced. Its tissue is nearly all of the involuntary variety. Its movements are 
mostly of a vermicular kind, and serve to carry the contents of the canal from 
the upper to the lower end. 
The serous membrane clothes the tube in its abdominal portion—that in which 
there is the largest variation in the size of the organs, the greatest necessity for 
activity of movement, and the most frequent liability to pressure from without. 698 
THE ORGANS OF DIGESTION. 
But all of these things—distension, contraction, peristalsis, compression—can 
take place without making trouble, for the organs have so slippery an outer sur- 
face that they glide freely on one another during the less movements, and slide 
elusively out of the way of extraneous force. 
Gras in the Alimentary Tube.—The tube in the larger part of its course gen- 
erally contains more or less gas, which, by keeping the opposite walls somewhat 
separated from each other, prevents the injury which would probably come from 
the prolonged rubbing together of these soft and delicate surfaces. In some 
regions, however, as in the gullet, the opposite surfaces of the membrane are in 
contact nearly all of the time; but in these cases the structure is very different 
from that in the stomach and intestines, especially as regards the epithelium, 
which, instead of being tender and in a single lamina, as in the latter organs, is 
hard and stratified, and capable of withstanding the influence of incessant 
pressure and friction. 
THE MOUTH. 
The mouth (os) (Fig. 745) is the organ in which are accomplished wholly 
or in part the functions of prehension, mastication, insalivation, gustatory sensa- 
VESTIBULE- 
HYOID' 
Fig. 745.—Sagittal section of the face and neck, showing the first portions of the alimentary and respiratory 
tracts. (Testut.) 
tion, and articulation. 
Its name is applied popularly not only to the cavity in the face, which consti- 
tutes the initial segment of the alimentary canal, but also to the aperture of 
entrance and to the lips ; but anatomists use it only in the first sense. It is not 
always an actual cavity—a fact demonstrated in sagittal frozen sections, in which THE MOUTH. 
699 
commonly its floor and roof are in contact, and its side walls hug the dental 
arches. Between this merely potential cavity and that of wide expansion is a 
great distance, within which are countless variations in shape ; but the mouth may 
conventionally be regarded as a rather oval, horizontal slit, presenting marked 
irregularities of size and form. Its virtual cavity is made real by separation of 
the lips or cheeks from the teeth, by the flattening of the tongue, or by the 
depression of the lower jaw. The oral space is divided by the apposed dental 
arches into the vestibule and the mouth proper. The former, vestibulum oris, has 
in front the lips, at the sides the cheeks, and its opposite boundaries are made by 
the outer surface of the gums and teeth; the latter, cavum oris, is bounded above 
by the hard palate, below by the tongue and the sublingual space, in front and at 
the sides by the inner surface of the gums and teeth, and behind by the soft palate 
and the aperture beneath it by which the mouth opens into the pharynx. The 
two portions communicate with one another by the gaps between the teeth and by 
the considerable space behind the last molar teeth. 
The Lips. 
The lips (labia), upper and lower, are musculo-membranous folds, enclosing 
the transverse slit which is the front aperture of the mouth. Each is attached to 
a jaw-bone just beyond the base of the alveolar process. The external limits 
have been given on page 23. From before backward they are composed of skin, 
muscle, areolar tissue containing glands, and mucous membrane, the last forming 
the free border as well as the lining. The skin, adherent to the muscle, presents 
no especial peculiarities, except the growth of strong hairs in the adult male. 
The muscular layer is mostly formed by the orbicularis oris, into which other 
muscles from various regions of the face are inserted. The areolar lamina is 
occupied by an almost continuous layer of racemose glands, called labial, which 
are practically identical in structure with the salivary glands. The mucous mem- 
brane is smooth and moist, and is reflected from the lips to the gums. A fold of 
it in the middle line at the junction with the gums forms a bridle, frcenum labii, 
for each lip. On its free border the lip is abundantly supplied with papillse. 
Everywhere its epithelium is flattened and stratified. 
The Cheeks. 
The surface-limits of the cheek have been detailed on page 23. A consider- 
able part of its surface is attached to the bones of the face; only the central 
portion is free, and clothed with mucous membrane, this being continuous with 
that of the lips, and, like it reflected to the gums. Five layers go to compose 
the cheek: skin, areolar tissue, deep fascia, muscle, and mucosa. The skin is 
continuous with that of the lips, and in the adult male is, to a large extent, 
covered with strong hairs. The areolar tissue is usually laden with fat-cells, 
these being most numerous in children and young women, and least abundant in 
the aged. The next layer is formed by the fasciae of the masseter and buccinator, 
which muscles constitute a large part of the fourth lamina. The mucous mem- 
brane, continued from that of the lips, is similar to it, but there is no glandular 
layer connected with it, as in the labial region. There are, however, a number 
of mucous glands, called buccal and molar, on the outer surface of the buccinator, 
each of which sends its excretory duct through the mucous membrane, and pours 
its fluid into the mouth. Here, too, the mucosa is perforated by the ductYrom 
the parotid gland. 
The Hard Palate. 
The hard palate (palatum durum) forms the roof of the mouth. Its basis is 
made by the palate processes of the upper jaw-bones and the horizontal plates of 700 
THE ORGANS OF DIGESTION 
the palate bones, which, immovably united and bordered in front and laterally by 
the drooping alveolar process, make a flattened vault of horse-shoe shape. Mucous 
membrane, smooth, tough, and continuous with that of the gums, lines the roof, 
being closely adherent to the periosteum at the alveolar margin and mid line; 
but, where such attachment does not exist, there is a compact layer of racemose 
glands, called palatine glands, resembling the salivary, and embedded in areolar 
tissue, which hugs the periosteum. Each of these glands sends its duct through 
the mucosa, so that the latter is plentifully dotted with their minute openings. 
The surface is roughened, especially in front, with low, obliquely transverse 
ridges, has numerous small papillae, and displays a median raphe, at whose ante- 
rior end is a tubercle, which marks the inferior orifice of the anterior palatine 
canal. 
Attached to the hind end of the hard palate, and drooping obliquely back- 
ward from it with perfect continuity of surface, is the soft palate (palatum molle), 
also called the velum pendulum palati 
(“ pendulous veil of the palate ”), which 
extends from side to side, and terminates 
below in an arched border, from the centre 
of which dangles a teat-like process, the 
uvula (“ little grape”). From the base of 
the uvula on each side the lower edge of 
the velum is, as it were, split, one part 
going outward, downward, and forward to 
the side of the tongue, the other outward, 
downward and backward to the side of the 
pharynx, leaving between them on the side 
wall of the region a triangular recess with 
its base toward the tongue. The former 
ridge is the anterior pillar of the palate, the 
latter the posterior pillar. The irregular 
opening bounded by the anterior pillars and 
the dorsum of the tongue is the isthmus of 
the fauces, the aperture by which the mouth 
communicates with the pharynx. The front 
(antero-inferior) surface, therefore, of the 
velum marks the posterior limit of the 
mouth, and all of the cavity behind this plane 
belongs to the pharynx. The free edges of 
the posterior pillars are nearer together 
than are those of the anterior pair, and 
hence both sets are seen distinctly, if the 
mouth is widely opened, and the tongue depressed. 
The Soft Palate (Fig. 746). 
Fig. 746.—The soft palate and tonsillar re- 
gions. (Testut.) 
Structure of the Soft Palate.—The soft palate is built upon a fibrous frame- 
work, which hangs down from the hind border of the hard palate. Into this are 
inserted various muscles, which constitute the bulk of the organ. Mucous mem- 
brane covers every part of it, that visible from in front being like the buccal, 
smooth, rosy, covered with stratified, flattened epithelium, while that on the oppo- 
site surface resembles the nasal mucous membrane, being uneven, red, and 
clothed with ciliated, cylindrical epithelium, except at its lowest part, where the 
cells are like those in front. Beneath the mucosa are many glands, the majority 
being on the oral side, and continuous with those of the hard palate. 
During swallowing the veil is lifted backward to the hind wall of the pharynx ; 
but in suction it is drawn down to the tongue. In articulation it is made to 
assume every attitude between these extremes. THE MOUTH. 
701 
The muscles of the soft palate are the palatopharyngeus, palatoglossus, levator 
palati, tensor palati, and azygos uvulae. 
Palatopharyngeus (Fig. 747) (“ the palate-pharynx muscle”).—Situation, at 
the side and back of the soft palate. Origin, in the velum, embracing the 
levator palati and azygos uvulae. 
Direction, downward, outward, and 
backward. Insertion, the upper 
and hind borders of the thyroid 
cartilage (mingling with the stylo- 
pharyngeus), and the lower part of 
the pharynx, extending to the mid- 
dle line. Action: it lifts the larynx 
and the tongue, pulls down the 
velum, and approximates the poste- 
rior pillars, shutting off* the oro- 
pharynx from the naso-pharynx. 
Nerves, probably from the pharyn- 
geal plexus through the eleventh 
cranial. Covered by mucous mem- 
brane, it forms the posterior pillar 
of the soft palate. This is joined 
by a fasciculus arising from the 
cartilage of the Eustachian tube, 
which has been described as a sepa- 
rate muscle, under the name of the 
salpingo-pharyngeus—the first part 
of the title referring to the trum- 
pet-shape of the end of the tube. 
Palatoglossus (Fig. 759) (“the 
palate-tongue muscle”).—Synonym, 
constrictor isthrai faucium, “ the 
constrictor of the isthmus of the 
fauces.” Situation, at the side and 
front of the soft palate. Origin, 
in the velum, being continuous with 
its opposite fellow. Direction, 
downward, outward, and forward. 
Insertion, at the side of the tongue. 
Action: it lifts the tongue, pulls 
down the velum, and approximates 
the anterior pillars, closing the 
pharynx from the mouth. Nerves, probably from the pharyngeal plexus through 
the eleventh cranial. Covered by mucous membrane, it forms the anterior pillar 
of the soft palate. 
Levator Palati (Fig. 747) (“ the lifter of the palate ”).—Situation, in the upper 
part of the velum. Origin, the under surface of the petrous portion of the tem- 
poral bone, in front of the carotid canal. Direction, downward, inward, and 
forward. Insertion: it blends with its opposite fellow. Action, lifting the velum. 
Nerve, probably the spinal accessory, through the pharyngeal plexus. 
Tensor Palati (“ the tightener of the palate ”).—Synonym, circumflexus, “ the 
muscle which bends around.” Situation, in the velum. Origin, the root of the 
internal pterygoid plate, the spine of the sphenoid, the Eustachian tube. Direc- 
tion, downward to the hamular process, then inward. Insertion, the middle of the 
soft palate, and the under surface of the palate bone. Action, tightening the 
velum. Nerve, the third division of the fifth. 
Muscles of the Soft Palate. 
Fig. 747.—Muscles of the soft palate, viewed from 
behind. The dorsal wall of the pharynx has been laid 
open. (Testut.) 702 
THE ORGANS OF DIGESTION. 
Azygos Uvulae (Fig. 747) (“ the unyoked (not-paired) muscle of the uvula,” 
—a misnomer, as there are two muscles).—Situation, in the soft palate, close to the 
mid line. Origin, posterior nasal spine. Direction, downward. The muscles of 
the two sides unite below, and terminate in a free, dangling end, making the bulk 
of the uvula. Action, shortening the uvula. Nerve, probably the spinal acces- 
sory, through the pharyngeal plexus. 
The teeth are dense, white structures, firmly implanted in sockets in the 
alveolar processes of the jaw-bones. They are essential parts of the chewing- 
apparatus, and are concerned in articulation. Each 
consists of three portions—a root or fang, a neck, and 
a crown. The surface toward the tongue is called 
“ inner,” and the opposite one is called “ outer.” 
The root is embedded in the bone, has a tapering 
shape, and fits accurately in its socket—an arrangement 
which ensures a distribution of pressure over the sur- 
face, and the removal of pressure from the tip of the 
fang, where the vessels and nerves pass to and from the 
tooth-cavity. The croicn is the portion which projects 
beyond the gum. The neck is a narrow strip between 
the fang and crown, is slightly, if at all, constricted, 
and is embraced by the border of the gum. 
In each jaw are sixteen teeth, arranged with bilateral 
symmetry, and all set obliquely, except the two nearest 
the middle line in the mandible. Classifying them ac- 
cording to their shape, and reckoning from the median 
line, we find in each lateral half of each jaw two incisors, 
one canine, two bicuspids, and three molars (Fig. 748). 
The Incisors (Fig. 749) (“cutters”) are the teeth 
by which portions of food are bitten off. The root of an incisor is a long cone ; 
THE TEETH. 
Fig. 748.—The teeth of the 
right half of the upper jaw in 
their sockets,viewed from below. 
UPPER INCISORS FRONT 
UPPER INCISORS REAR 
UPPER INCISORS SIDE 
LATERAL 
CENTRAL 
CENTRAL 
LATERAL 
LATERAL 
CENTRAL 
CENTRAL 
LATERAL 
CENTRAL 
LATERAL 
LATERAL 
CENTRAL 
CENTRAL 
LATERAL 
KTERAL 
CENTRAL 
CENTRAL 
LATERAL 
CENTRAL 
LATERAL 
LOWER INCISORS—FRONT 
LOWER INCISORS—REAR 
LOWER INCISORS—SIDE 
Fig. 749.—The incisor teeth from different points of view. (Testut.) 
its crown presents an anterior, slightly convex surface, and a posterior, slightly con- 
cave surface, the two meeting in a sharp free edge. The central incisors (those THE 310 UTH. 
703 
nearest the mid-line) of the upper set are larger than the lateral; but the central 
incisors of the lower jaw are smaller than their laterals. 
The Canine (Fig. 750), so-called from its prominence in animals of the dog- 
tribe, has a longer fang than an incisor. Its crown terminates in a sharp point, 
technically a cusp, from which comes the name, “ cus- 
pidate,” occasionally employed. An upper canine is 
vulgarly called an eye-tooth, and a lower a stomach- 
tooth, each from the direction of its fang. 
A Bicuspid (Fig. 751), as its name implies, has 
two prominences or cusps on its crown. From its 
situation in front of the next group it is also called 
premolar. Its root shows an attempt at division. 
Molars (“millstones”) (Figs. 752, 753) are thus 
named from their being concerned in grinding the 
food, and are also called multicuspids from their having 
three or more cusps on their summits, double teeth 
from their size, and jaw-teeth from the room which 
they occupy. In the upper set the molars have three 
fangs each; their mates in the lower have but two 
each. The third molar is, with fine irony, called the 
wisdom-tooth, because it does not appear until the late 
teens. The absence of this tooth about once in eight 
times, and its crowded condition in many cases, when 
present, point to the gradual lessening of the size of 
the jaws in proportion to the diminution of the work 
required of them in civilized life. 
Excepting the last upper molar, each tooth touches 
two in the opposite set, when the jaws are closed 
(Fig. 754). The upper dental arch is a little larger 
than its fellow, and overlaps it in front, so that the 
cutting edge of the superior incisors glides downward 
on the anterior surface of the lower, as one blade of a pair of scissors acts upon 
the other. 
UPPER CANINE OF RIGHT SIDE 
FRONT 
REAR 
SIDE 
FRONT 
REAR 
SIDE 
LOWER CANINE OF RIGHT SIDE 
, FiG 750.-The_canine teeth 
from different points of view, 
(Testut.) 
Sets of Teeth. 
The teeth grow in two series, the one in infancy, the other in childhood and 
youth. The former are displaced by the latter, and, therefore, are named tempo- 
rary, or first teeth. They are also called deciduous, because they are shed, and 
milk-teeth on account of their development during the period of lactation. Those 
of the later set are called permanent, or second teeth, and it is they which have 
just been described (Fig. 755). 
The Temporary Teeth are twenty in number, there being five in each lateral 
half of each jaw, namely two incisors, one canine, and two molars. It will be 
observed that there are no bicuspids, and no third molar. The bicuspids of the 
permanent set take the place of the temporary molars, and the jaw grows suf- 
ficiently to give room for the permanent molars, which are the successors of no 
other teeth. 
Eruption of the Teeth.—The temporary teeth usually begin to appear when 
the baby is about seven months old, and he has his full score by the time that he 
is two years of age. Before any of the milk-teeth are shed, the first grinders of 
the second set are fully developed. They are called the six-year molars in cele- 
bration of the time of their advent. The others of the series consume a dozen 
years in their “cutting,” as their protrusion through the gum is commonly 
called. 
There are so many exceptions to any rule, which states the precise date of 
appearance of the teeth, that it is well nigh useless to present such a formula. 
But it is desirable to know the order in which they may be expected, and this is 704 
THE ORGANS OF DIGESTION. 
presented in Fig. 755. The diagram also gives the position in the dental arch 
of the teeth of each set and shows what kind of permanent tooth succeeds each 
UPPER BICUSPIDS OF RIGHT SIDE 
OUTER SURFACE 
INNER SURFACE 
FRONT SURFACE 
FIRST 
SECOND 
FIRST 
SECOND 
FIRST 
SECOND 
FIRST 
>SURFACE 
SECOND 
FIRST 
GRINDING 
’ SURFACE 
SECOND 
FIRST 
SECOND 
FIRST 
SECOND 
FIRST 
SECOND 
OUTER SURFACE 
INNER SURFACE 
FRONT SURFACE 
Fig. 751.—The bicuspid teeth from different points of view. (Testut.) 
LOWER BICUSPIDS OF RIGHT SIDE 
temporary tooth. It is to be noted, however, that the permanent teeth appear in 
the jaw on the lingual side of the temporary, and not, as might be inferred from 
UPPER MOLARS OF RIGHT SIDE 
OUTER SURFACE 
INNER SURFACE 
FIRST 
SECOND 
THIRD 
FIRST 
SECOND 
THIRD 
FIRST 
SECOND 
THIRD 
FIRST 
SECOND 
THIRD 
OUTER SURFACE 
INNER SURFACE 
Fig. 752.—The molar teeth viewed from the outer and inner sides. (Testut.) 
LOWER MOLARS OF RIGHT SIDE 
this diagram, on the labio-buccal side. The lower tooth of a given kind usually 
is cut just before its mate above appears. THE MO UTIL 
705 
Method of Displacement of Temporary Teeth.—The temporary teeth are replaced 
by the permanent in the following manner : the tooth which is to succeed the 
deciduous tooth is pushed upward by the continual growth of the dentine of its 
fang. Its enamel is crowded against the root of the milk-tooth, cuts off its nutri- 
tion, and, by the incessant pressure of its dense substance upon the less hard 
materials composing the root of the tooth above, causes the latter to dwindle 
away, particle by particle, the molecules disappearing by absorption, until all of 
FRONT SURFACE 
UPPER MOLARS OF RIGHT SIDE 
FIRST 
SECOND 
THIRD 
GRINDING SURFACE 
FIRST 
SECOND 
THIRD 
FIRST 
SECOND 
THIRD 
GRINDING SURFACE 
FIRST 
SECOND 
THIRD 
FRONT SURFACE 
LOWER MOLARS OF RIGHT SIDE 
Fig. 753.—The molar teeth—their front and grinding surfaces. (Testut.) 
the root has vanished, and the only support of the crown is that afforded by the 
adhesion of the gum to the neck. Then the crown is knocked off by some slight 
force, and in its place appears that of its permanent successor. When the per- 
manent tooth is not aimed accurately at the root of the temporary, but shoots by 
it, the latter remains undisturbed. 
Morphological Character of a Tooth.—A tooth, though intimately connected 
MOLARS 
BICUSPIDS 
CANINE 
INCISORS 
Fig. 754.—Diagram of the dental arches, seen from the right side, showing their reciprocal relations. 
(Testut.) 
MOLARS 
BICUSPIDS 
CANINE 
INCISORS 
with the bony skeleton, is really a calcified papilla of the mucous membrane. A 
portion of the alveolar process grows around its base, and furnishes a snug socket 
for it; but, in spite of its density and the solidity of its implantation, it is com- 
parable with other papillae, such as that of a hair-follicle. The changes in the 
epithelium of the hair-papilla are unlike those which take place in that of the 
tooth-papilla, and, consequently, the result is very different, although in both 
cases the modification is in the direction of hardening; but, philosophically con- 706 
THE ORGANS OF DIGESTION 
side red, the hair and the teeth are closely related, as will be seen, if one studies 
the development of the two. 
PERMANENT 
CENTRAL 
INCISOR 
CENTRAL 
INCISOR 
r LATERAL 
INCISOR 
s. INCISOR 
CANINE 
'lateral) 
INCISOR 
CENTRAL 
INCISOR 
CENTRAL 
INCISOR j 
r lateral 
s^INCISOR 
CANINE 
/ FIRST 
f BI- 
CUSPID I 
'canine > 
TEMPORARY 
.canine' 
FIRST \ 
k Bl- ) 
\CUSPID 
r FIRST i 
MOLAR / 
FIRST 
I MOLAR 
SECOND 
BI- 
CUSPID 
SECOND 
BI- 
CUSPID 
SECOND 
MOLAR 
SECOND 
MOLAR 
FIRST 
MOLAR 
FIRST 
MOLAR 
SECOND 
MOLAR 
SECOND 
MOLAR 
THIRD 
MOLAR 
THIRD 
MOLAR 
Fig. 755.—Diagram showing what permanent tooth replaces each temporary tooth, and also the order of 
succession of the teeth of each set. (F. H. G.) 
Just before the six-year molars are erupted from the gum, forty-eight teeth in 
various stages of formation and retrogression can be recognized in the two jaws 
CENTRAL 
INCISOR 
Fig. 756.—The jaws of a child of seven and a half years, the external table of bone having been cut away 
to show the stage of second dentition. (Testut.) THE MOUTH. 
707 
—twenty of the temporary set, and twenty-eight of the permanent. The four 
wisdom-teeth at this time are only embryonic buds (Fig. 756). 
The Gums. 
The gums (gingivae) are dense, smooth mucous membrane, fused upon the 
periosteum of the alveolar processes. They are very resistant to pressure, and 
have comparatively slight sensitiveness. 
The floor of the mouth is formed mainly by the tongue, in small part by the 
sublingual structures. 
THE TONGUE. 
The tongue (lingua) (Fig. 757) is composed mostly of voluntary muscles, 
which give it protean power of changing its shape. Its upper surface can be 
convexed or concaved ; its point can be thrust forward bevond the lins, drawn 
backward nearly or quite 
to the junction of the hard 
and soft palates, swept 
over the entire surface of 
the vestibule above and 
below; in short, the free 
portion of this organ can 
be made to assume such a 
multitude of forms as to 
defy description. This 
capacity accounts for its 
varied usefulness in the 
processes of prehension, 
chewing, swallowing, 
speech, touch, taste, and 
expression. 
The part of the tongue 
which presents a free sur- 
face upward and backward 
is called the dorsum. The 
anterior two-thirds of this 
is in the floor- of- the 
mouth, the posterior third 
in the front wall of the 
pharynx. The pharyn- 
geal part of the dorsum 
forms the very sloping 
floor of the space marked 
off on each side by the 
two pillars of the soft 
palate. It has a mam- 
mil lated appearance, 
caused by the presence of 
numerous racemose glands 
and lymphoid masses. 
Just behind the apex of the series of circumvallate papillae (described on a 
previous page) is a little aperture, the foramen ccecum (“ blind hole ”), the 
remnant of a fnetal canal. At the lowest part of the pharyngeal surface the 
mucosa is raised into three sagittal folds connecting the tongue with the larynx, 
the central one being the largest, and inserted into the upper surface of the epi- 
glottis. The oral portion of the dorsum, when entirely at rest, is convex in every 
UVULA 
I 
PHARYNX 
TONSIL 
EPIGLOTTIS 
CIRCUM- 
VALLATE 
PAPILL/E 
Fig. 757.—Dorsal surface of the tongue. (Testut.) 708 
THE ORGANS OF DIGESTION. 
direction. It ends anteriorly in a somewhat pointed tip. Its mucosa is specialized, 
and has already been described in the chapter on the organs of the special senses. 
The Sublingual Space (big. 758).— 
Lifting up the tip of the tongue we 
obtain a view of the sublingual space. 
We see that the mucous membrane of 
the under side of the tongue is smooth, 
and not furnished with such specialized 
papillae as mark the upper surface. A 
fore-and-aft fold, the frcenum linguae 
(“bridle of the tongue”), in the mid 
line, connecting the tongue with the 
jaw, limits the backward movements 
of the apex. On each side of this bridle 
opens a duct from the mbmaxillary saliv- 
ary gland. The sublingual salivary 
gland forms an elongated elevation in 
the gutter between the tongue and the 
jaw on each side, and the openings of 
its many ducts are found in the region 
of the frsenum. Beneath the rest of 
the mucous membrane in this space are 
various lingual muscles. 
Structure of the Tongue.—As pre- 
viously stated the tongue is made up 
largely of muscles. These are ar- 
ranged in pairs with bilateral sym- 
metry, and when we speak of the action 
of a given muscle, we shall imply the 
simultaneous contraction of its fellow of the opposite side. 
Mingled with the muscles of the tongue are fibrous, and adipose tissues, and 
many vessels and nerves. Its framework consists of a vertical, median, fibrous 
plate, extending from the hyoid bone to the tip of the tongue, and a fibrous 
lamina near the surface of the dorsum and edges in each lateral half. 
The muscular part of the tongue comprises two groups—the intrinsic and the 
extrinsic muscles. The distinction between them is somewhat arbitrary. If the 
connections of the tongue with the hyoid bone, the styloid process of the tem- 
poral, the mandible, the velum palati, and the pharynx be severed (the muscles 
in each case being traced to their attachments) and the organ be then removed, 
we shall see that there is a firm central portion of definite shape, tapering from 
behind forward, and that from this body project a number of muscular bands 
of various forms and sizes. The intrinsic muscles are found only in the central 
mass; the projecting bands are parts of the extrinsic muscles, the other parts 
being embedded in the central mass, in which their fibres decussate with those of 
the intrinsic muscles. 
Fig. 758.—Under surface of tongue and the sub- 
lingual space, showing openings of salivary ducts. 
The mucosa of the left side is partly removed, and 
shows the ranine artery, the lingual nerve, and the 
gland of Blandin. (Testut.) 
The Lingualis Muscle.—The intrinsic mass or tongue proper is sometimes 
spoken of as the lingualis muscle; but it is convenient to divide it into four por- 
tions—the superior, the inferior, the transverse, and the vertical. They are all 
supplied by the hypoglossal nerve. 
The superior lingualis consists of longitudinal fasciculi, which lie near the 
upper surface from the hyoid to the apex, attachments being made all along with 
the submucous tissues. Its action produces shortening of the tongue, and longi- 
tudinal grooving of its dorsum. 
The inferior lingualis is a large bundle, which runs under the edge of 
the tongue in its whole length. It shortens the tongue and rounds up its 
dorsum. 
The transverse lingualis is made up of fibres which arise in the median septum THE MOUTH. 
709 
and run to the dorsum and margin, where they are inserted into the fibrous 
lamina. It diminishes the width and increases the length of the organ. 
The vertical lingualis is composed of small fasciculi, which course from the 
STYLOID PROCESS 
ORIGIN OF 
STYLOHYOID 
-mandible: 
INSERTION OF STYLOHYOID 
Fig. 759.—Muscles of the tongue, viewed from the right side. (Testut.) 
PULLEY OF DIGASTRIC 
dorsum to the under surface, curving with their concavity outward. Its fibres 
are interlaced with those of the transverse lingualis. It broadens and flattens 
the tongue. 
The Extrinsic Muscles of the Tongue. 
The extrinsic muscles of the tongue are the genioglossus, the hyoglossus, the 
styloglossus, and the chondroglossus. To this list is sometimes added the pala- 
toglossus ; but it seems better to include this with the muscles of the soft palate, 
already described. 
Genioglossus (Fig, 759) (“the chin-tongue muscle”).—Synonym, geniohyo- 
glossus, “ the chin-hyoid-tongue muscle.” Situation, in the middle line of the 
tongue. Origin, the upper genial tubercle. Direction, divergent—backward, 
upward, and to all points between. Insertion, the hyoid bone and the whole 
length of the tongue in and at the sides of the mid line. Action: the back part 
thrusts the tongue forward ; the front part retracts the tip of the tongue; the 
part between the apex and the base depresses the mid line, thus forming a gutter. 
Nerve, the hypoglossal. 
Hyoglossus (Figs, 759, 760) (“the hyoid-tongue muscle”).—Situation, 
between the hyoid and the side of the tongue. Origin, the great cornu and the 
body of the hyoid. Direction, upward and forward. Insertion, the side and dor- 
sum of the tongue, blending with the styloglossus. Action, retraction and depres- 
sion of the tongue. Nerve, the hypoglossal. 
Styloglossus (Figs. 759, 760) (“the styloid-process-tongue muscle”).—Situa- 
tion, between the side of the base of the skull and the side of the tongue, outside of 
the pharynx. Origin, the front of the styloid process of the temporal bone, and 
the stylomandibular ligament. Direction, forward, downward, and a little 
inward. Insertion, the whole length of the side and under part of the tongue. 
Its fibres blend with those of the hyoglossus and palatoglossus. Action : it draws 
the tongue backward, and lifts its base. Nerve, the hypoglossal. 710 
THE ORGANS OF DIGESTION. 
Chondroglossus.—“ The cartilage-tongue muscle/’ so called from its attach- 
ments to the small cornu (which is usually cartilaginous) of the hyoid and to the 
tongue. Situation, at the side of the tongue below, under cover of the hyoglossus. 
Origin, the small cornu and body of the hyoid. Direction, upward and forward. 
Insertion, the dorsum of the tongue. Action :it retracts and depresses the tongue. 
Nerve, the hypoglossal. 
THE PHARYNX. 
Behind the nasal passages, the mouth, and the larynx, beneath the base of the 
skull, and above the upper end of the gullet, is a hollow organ of irregular shape, 
which belongs not only to the alimentary tube, but to the respiratory system, also. 
It has no name in our vernacular, but is known technically as the pharynx (Fig. 
745). The upper part, behind the nose, is the naso-pharynx; the middle portion, 
back of the mouth, is the oro-pharynx; and the lowest segment, dorsal to the 
larynx, is the laryngo-pharynx. The anterior lower limit of the naso-pharynx is 
at the border of the hard palate; of the oro-pharynx at the upper level of the 
hyoid bone ; and of the laryngo-pharynx at the lower level of the cricoid cartil- 
age, which nearly coincides with that of the fifth cervical vertebra. 
Food passes from the mouth into the oro-pharynx, through the laryngo- 
pharynx, and into the gullet; and inspired air goes from the nose into the naso- 
pharynx, through the oro-pharynx, and enters the larynx. Thus the middle seg- 
ment of this organ is common to the alimentary and respiratory systems, and the 
tracks followed by the food and the air cross obliquely in it. 
Like the mouth the pharynx is bilaterally symmetrical. It is widest (nearly 
one inch and a half) in the upper laryngeal portion, and narrows above and 
below, having its least diameter (half an inch) at its junction with the gullet. 
Ventro-dorsally its measurement is everywhere small, only opposite the mouth 
being more than four-fifths of an inch. It is about five inches long. In short, 
the cavity of the pharynx may fairly be regarded as a wide side-to-side chink, in 
front of the upper five cervical vertebra?. 
Openings of the Pharynx,—ln the naso-pharynx are four openings—one at 
each side for the Eustachian tube, leading to the middle ear, and one forward 
for each of the lateral halves of the nose,—the posterior nares. In the oro- 
pharynx is the opening from the mouth, the isthmus of the fauces, between the 
anterior pillars of the palate. The laryngo-pharynx opens at its lower end into 
the gullet, and at its upper, anterior part into the larynx. 
The pharynx is firmly fastened to the neighboring parts at its summit, and in 
the front part of its nasal and oral portions; but its attachments elsewhere are 
areolar and loose, so that its lower third can be elevated, and its rear wall 
advanced, as in swallowing. 
Tunics of the Pharynx.—Here, as elsewhere in the alimentary tube, the wall 
is composed of three coats; but the middle one is so much condensed that its 
areola? are largely obliterated, and the tunic is more like a fascial layer. 
The mucous membrane, continuous with that of the nose, middle ears, mouth, 
larynx, and gullet, is covered with ciliated cells as far down as the level of the 
hard palate, but below this is flattened and non-ciliated. On the back (dorso- 
superior surface) of the soft palate the cells are ciliated, except at the free edge. 
In and beneath the mucosa are many racemose, mucous glands. The corium is 
particularly rich in lymphoid tissue, and at the pharyngeal vault and across the 
posterior part of the oro-pharynx are accumulations of lymphoid material, which, on 
account of similarity of structure, have been named the pharyngeal tonsil. High 
up in the middle line, and running upward and backward to the base of the 
skull is a blind depression, called the pharyngeal bursa. 
The muscular tunic is composed of five pairs of muscles, of which three are 
constrictors—upper, middle, and lower—having for their function the diminution THE PHARYNX. 
711 
of the calibre of the pharynx, and the others—the stylopharyngeus and palato- 
pharyngeus—are elevators, which lift up the pharynx and larynx. The last of 
these has already been described in connection with the soft palate. 
Muscles of the Pharynx. 
Constrictor Inferior (Figs. 760, 761) (“the lower constrictor”).—Situation, the 
side and back of the lower part of the pharynx. Origin, the cricoid and thyroid 
cartilages of the larynx. Direction, backward, inward, and upward, diverging 
from its origin. Insertion, the median 
tendon, common to it and its fellow 
opposite, extending nearly to the basilar 
process of the occipital bone. It over- 
laps the middle constrictor. Action :it 
compresses the pharynx, mainly ventro- 
dorsally ; it also moves the larynx up- 
ward and backward. Nerves, from the 
pharyngeal plexus, and the external 
and inferior laryngeal. 
Constrictor Medius (Figs. 760, 761) 
(“ the middle constrictor ”).—Situation, 
at the side and back of the middle part 
of the pharynx. Origin, the cornu 
of the hyoid, and stylohyoid ligament. 
Direction, divergent—all portions back- 
ward and inward, the inferior down- 
ward, and the superior upward. In- 
sertion, the common tendon in the 
middle line in almost the entire length 
of the pharynx. Action :it compresses 
the pharynx, chiefly ventro-dorsally; 
and it draws the hyoid backward and 
unward. Nerves, from the nharynsreal nlexus. 
EXTERNA L 
AUDITORY 
MEATUS 
Fig. 760.—Muscles of the pharynx, viewed from the 
right side. (Testut.) 
Constrictor Superior (Figs. 760, 761) (“the upper constrictor”).—Situation, 
at the side and back of the upper part of the pharynx. Origin, the side of the 
tongue, the mucosa of the mouth, the mylohyoid ridge, the pterygomaxillary liga- 
ment, and the lower fourth of the hind border of the internal pterygoid plate. 
Direction, divergent—all parts backward and inward, the superior upward, and 
the inferior downward. Insertion, the common tendon in the middle line from 
the basilar process half way, or more, to the gullet. Action, approximation of 
the lateral walls of the upper part of the pharynx. Nerves, from the pharyngeal 
plexus. 
The name pharyngoglossus (glossopharyngeus) is applied to certain fasciculi 
which extend from the superior constrictor to the tongue—the upper losing itself 
in the palatoglossus and styloglossus, the lower merging into the hyoglossus, 
genioglossus, and lingualis. 
Stylopharyngeus (Figs. 760, 761) (“the styloid-process-pharynx muscle”).— 
Situation, at the side of the pharynx, and mesial to the middle and lower con- 
strictors. Origin, the styloid process of the temporal bone. Direction, down- 
ward and inward. Insertion, the upper and hind borders of the thyroid cartilage, 
mingling with the palato-pharyngeus. Action, lifting the pharynx and larynx. 
Nerve, the glosso-pharyngeal. 
The Tonsils (Fig. 746). 
In the recess formed by the divergence of the pillars of the palate on each 
side is a flattened, ovoid body, the tonsil (tonsilla) or almond [amygdala), whose. 712 
THE ORGANS OF DIGESTION. 
mesial face can easily be seen, when the mouth is widely opened and the tongue 
depressed. Its position is internal to that of the angle of the jaw. Its external 
surface is attached to the upper constrictor by areolar tissue. 
Pig. 761.—Muscles of the pharynx, viewed from behind, together with the associated vessels and nerves. 
(Modified from Testut.) 
The tonsil is substantially a collection of lymph-nodules, with a distinct cap- 
sule on its attached surface, and a continuation of the mucosa of the pharynx on 
its exposed surface, which is irregularly pitted with blind holes of varying size. 
Mucous glands open into these pits, and with their secretion are mingled great 
numbers of lymph-cells, many of which appear in the spittle as salivary cor- 
puscles. 
THE GULLET. 
Between the levels of the upper border of the sixth cervical vertebra and that 
of the eleventh thoracic—a distance of about ten inches—extends the gullet or 
oesophagus (“ carrying eatables ”), the tube connecting the pharynx and the THE GULLET. 
713 
stomach (Fig. 762). Its direction is nearly that of the part of the spinal column 
near which it runs—slightly curved with its concavity forward. It presents slight 
lateral bends of no practical importance. It gradually expands at its lower part, 
and then is a little constricted at its passage through the diaphragm. Excepting 
during the passage through it of distending substances, its condition is one of col- 
lapse, its dorsal and ventral walls being in 
contact, its mucosa folded into longitudinal 
rugse, and the bore of the tube obliterated. 
The mucosa, like that in the succeeding 
portions of the alimentary canal, is limited 
in its depths by a muscularis mucosse. Its 
free surface has a stratified, flattened epi- 
thelium. The areolar coat is thick, and 
contains many mucous glands, which open 
into the lumen. The muscular tunic dis- 
plays a peculiar transition from the striated 
variety, which alone is seen in the pharynx, 
to the smooth, which is the only kind 
occurring in the stomach. For a short 
distance from the beginning we find only 
striped muscle ; then for a little way a mix- 
ture of the two varieties; and, finally, in 
the lower half, nothing but the muscular 
tissue of organic life. The inner layer is 
circular, the outer longitudinal. The gul- 
let is connected with the structures in the 
midst of which it lies by a sheath of areo- 
lar tissue. 
FIRST THORA 
CIC VERTEBRA 
THE ABDOMINAL CA VITY. 
TWELFTH THORA 
CIC VERTEBRA 
The portion of the alimentary canal 
which is below the diaphragm is contained 
in the abdomen, and it is desirable to study 
this cavity before proceeding to the consid- 
eration of the viscera which it holds. 
The boundary between the thorax and 
abdomen is made by the diaphragm. This 
muscle forms a dome over the belly-cavity, 
its highest part rising to the level of the 
junction of the fourth costal cartilage with 
the sternum, and, consequently, the abdomen 
greatly encroaches upon the space, which a 
superficial inspection of the thoracic cage 
would lead one to assign to the chest. The 
cubic capacity of the thorax is very small compared with that of the abdomen, 
largely owing to this invasion of its (expected) territory. 
The lower end of the abdomen is limited by the structures which clothe the 
inner surface of the bony pelvis. Muscles form the bulk of the front and lateral 
walls, and a good part of the dorsal, the last being completed by a portion of the 
vertebral column. 
It has a serous lining, outside of which is a fibrous or areolar tunic, which is 
variously named in different parts. (See Fasciae, pages 359-361.) Apertures in 
its walls give passage to numerous organs : the aorta, inferior vena cava, oesopha- 
gus, and various nerves, above; the rectum, urethra, spermatic cords or round 
ligaments of the uterus, the vessels and nerves of the lower limbs, and, in the 
Fig. 762. (Esophagus and stomach in their 
natural relations to the vertebral column and 
the aorta. (Testut.) 714 
THE ORGANS OF DIGESTION. 
female, the vagina, below; besides which should be mentioned the openings of 
the oviducts (Fallopian tubes) of the female. 
Regions of the Abdomen (Fig. 763). 
For generations it has been customary to divide the abdomen into nine regions 
for convenience of description : one near the centre, called umbilical, with a lum- 
RIGHT 
HYPOCHON- 
DRIAC 
REGION 
EPIGASTRIC 
REGION 
LEFT 
HYPOCHON- 
DRIAC 
REGION 
OF TENTH RIB 
RIGHT 
LUMBAR 
REGION 
UMBILICAL 
LEFT 
LUMBAR 
REGION 
HIGHEST LEVEL 
OF ILIAC CREST 
REGION 
ANT. SUP. 
ILIAC SPINE 
RIGHT 
ILIAC 
\region 
LEFT 
ILIAC 
region/ 
HYPOGASTRIC 
REGION 
Fig. 763.—Regions of the abdomen, delimited by the author’s method 
(F. H. G.) 
bar on each side; above the umbilical, the epigastric (“ upon the stomach ”), 
with a hypochondriac (“ under the cartilage ”) on each side; and below the 
umbilical, the hypogastric (“ under the stomach ”), with an iliac on each side. 
The delimitation of these regions is not uniformly made by authors. The writer 
called attention to this fact and to the need of agreement among anatomists some 
years ago, and embodied his suggestions in a paper read to the Association of 
American Anatomists in 1892. Having seen no proposition which appears more 
reasonable and useful in the premises, he presents his plan here. 
A line is drawn around the body at the level of the anterior superior spinous 
processes of the ilium, and another at the Imvest point of the tenth costal cartilages. 
These lines stand for the peripheries of horizontal planes, which completely 
divide the abdomen into three sections. Each section is cut into three by a ver- 
tical plane running ventro-dorsally through the middle of each inguinal (Poupart’s) 
ligament. 
These are superficially indicated on the front of the abdomen in Fig. 763. 
The advantages of this method are that it brings the umbilicus wholly into 
the umbilical region, which is rather rarely the case, when the lower horizontal is 
drawn at the level of the iliac crests; that the guide to the upper horizontal is a 
prominence easily found through the integuments, and that this plane divides the 
part of the abdomen above the lower horizontal more equally than does that THE STOMACH. 
715 
usually given ; and, finally, that the perpendicular plane on each side starts 
from a prominent landmark, and fairly apportions each of the three zones. 
The abdominal cavity is lined with the largest of the serous membranes, the 
peritoneum. At various places this membrane is reflected from the wall onto the 
contained viscera, to some of which it furnishes a slight, to others a considerable, 
and to others still a practically complete outer tunic, thus justifying its name, 
which means literally something “ stretched around.” Until the anatomy of the 
abdominal viscera is learned, a description of the peritoneum cannot be appre- 
ciated ; and, therefore, further consideration of the subject will be deferred until 
the discussion of the digestive organs has been completed. 
THE STOMACH. 
The gullet perforates the diaphragm, and almost immediately ends in the 
stomach (stomachics, paster), the tube expanding into a great bag (Fig. 764). The 
OESOPHAGUS 
3 CARDIAC END 
GREATER 
'CURVATURE 
Fig. 764.—Stomach and duodenum, the liver and most of the intestines having been removed 
(Testut.) 
stomach is just beneath the diaphragm and behind the anterior abdominal wall, 
in the epigastric and left hypochondriac regions. Its shape and attitude are 
worthy of especial attention. It looks somewhat like a pear with the large end 
up, and the small end bent sidewise to the right. Its front and rear surfaces are 
moderately convex. Looking at it from before, it is seen that a continuation of 
the right margin of the oesophagus downward coincides with the upper two-thirds 
of the right border of the stomach, the remaining third of this border bending 
sharply to the right and backward, thus completing what is known as the small 
curvature. The great curvature begins at the end of the gullet on the opposite 
side, making a somewhat acute angle with the left border of this tube. It then 716 
THE ORGANS OF DIGESTION 
passes upward and to the left to the diaphragm, is in contact with the under sur- 
face of the latter for some distance, sweeps downward in a generous curve with 
its convexity to the left, continues in a somewhat flattened line to the right, is 
here a little indented, and finally turns abruptly up and back, terminating at the 
outlet-end, close to the small curvature. 
Particular attention is called to the following facts : the general direction of 
the long axis of the stomach is vertical; the small curvature faces mostly to the 
right; the great curvature is directed mainly to the left; the aperture of entrance 
(oesophageal opening) is but slightly to the left of the middle line of the body, and 
looks downward; the hole of exit (intestinal opening) is on a lower plane, close 
to the mid line, and looks directly backward—a point not well shown in Fig. 764. 
The curvatures or borders are the lines of reflection of the peritoneum. 
The preceding statements apply to the organ when it is not distended; but, 
when it is distended, some differences are observed. Then the great curvature is 
tilted toward the front, the small end is moved two inches or more toward the 
right, and the pressure on the diaphragm may be such as to interfere seriously 
with the freedom of action of the heart, which is situated in part immediately 
over the stomach on the upper surface of the diaphragm. 
The large end of the stomach is called, on account of its nearness to the heart, 
the cardiac end, or simply the cardia ; the small is named the pyloric end, from 
the pylorus, presently to be described. 
The before-mentioned indentation of the great curvature near the lower end is 
a part of a slight constriction, and the portion of the cavity between it and the 
intestinal opening is called the antrum pyloricum (“ pyloric cave ”). 
The Tunics of the Stomach. 
The tunics of the stomach conform to the rule previously stated. 
The Serosa.—Passing from the transverse fissure of the liver are two layers of 
serous membrane, which constitute the gastro-hepatic (“stomach-liver ”) omentum. 
After continuing downward for 
about two inches, they reach the 
small curvature of the stomach, 
where they divide, clothe respect- 
ively the front and back surfaces of 
this viscus, meet along the great 
curvature, unite again, and continue 
downward to help form the great 
omentum. A very narrow strip of 
uncovered surface may be found 
along each of the two curvatures, 
indicating respectively the places 
of separation and reunion of the 
peritoneal lamellae. The adhesion 
of the serosa is closest at the centre 
of the front and back surfaces, but 
gradually becomes looser toward the 
borders. 
The Muscular Coat has two com- 
plete layers—an outer, longitudinal, 
and an inner, circular (Fig. 765). 
Besides these two distinct layers 
some oblique fasciculi are found, 
internal to the circular. This criss- 
cross arrangement of the layers contributes greatly to the strength of the stomach- 
walls. The circular layer increases in thickness toward the small end, and there 
is such an augmentation of its fibres around the intestinal opening as to con- 
Fig. 765.—Diagram to show the direction of the fibres in 
the three muscular layers. (Testut.) THE SMALL LNTESTINE. 
717 
stitute a thick, circular sphincter, called the pylorus (“gate-keeper”), the side 
toward the stomach sloping, and that toward the bowel being abrupt. The aper- 
ture is the pyloric orifice (Fig. 766). 
The Areolar Coat, called also submucous and vascular, is loose, and its meshes 
are largely occupied with the vessels and nerves going to and from the coats 
between which it lies. 
The Mucous Membrane is thrown into irregular, longitudinal folds (rugae) when 
the organ is flaccid, but becomes smooth during distension. Its corium is mostly 
occupied by tubular between which is fibrous tissue, containing capillaries 
and nerves; and beneath these structures is a muscularis mucosae, which sends 
some of its fibres up between these follicles. The surface epithelium consists of a 
single layer of columnar cells, many of which are goblet. The glands are all tubular 
depressions of the surface, and their length is but a trifle less than the thickness of 
the membrane. They are of two varieties, one, the cardiac glands or proper gastric 
glands, being found in the large end and middle third of the stomach; and the 
other, the pyloric glands, in the region of the small end. 
They are arranged in little groups, which are bounded 
by minute elevations of the surface. 
The cardiac glands (Fig. 767) are simple tubular 
depressions, consisting of a duct, neck, and fundus or 
body. The duct is short, has a wide mouth, and is lined 
with columnar epithelium, a continuation of that upon 
the general, free surface. Its cells overlap one another 
a little. In the neck the cells become short and broad. 
The fundus is wavy or spiral, and is furnished with two 
kinds of cells : the central, rather conoidal, and more 
numerous; the parietal, larger, usually not reaching the 
SURFACE OF MUCOSA 
.PARIETAL 
0 CELL 
—SEROUS COAT 
-LONGITUDINAL MUSC. LAYER 
-CIRCULAR MUSC. LAVER 
-AREOLAR COAT 
"MUCOUS COAT 
[central 
\ CELLS 
DUODENUM 
PYLORIC 
ANTRUM 
Fig. 766.—Vertical section at the junction of the stomach and duodenum, 
showing the disposition of the coats. Semidiagrammatic. (Testut.) 
Fig. 767.—Cardiac gland in 
longitudinal section. (F. H. G.) 
bore of the tube, but communicating with it through minute cracks between the 
overlying central cells. 
The pyloric glands have a very wide and deep duct, into the bottom of which 
open several divisions (funduses), which are wavy or even tortuous. The epithe- 
lium is in all parts very similar to that on the surface of the mucosa. Between 
the divisions is the true corium material, and at frequent intervals are irregular 
masses of lymph-adenoid material. 
THE SMALL INTESTINE. 
The small intestine (intestinum tenue) (Fig. 779) is that portion of the alimen- 
tary canal which begins on the distal side of the pyloric valve, and ends on the 
proximal side of the ileo-csecal. In other words it extends between stomach 718 
THE ORGANS OF DIGESTION. 
above and large intestine below. Its average length is twenty feet or more ; and, 
as it is all contained in the abdominal cavity, which also lodges many other 
organs, it is necessarily subjected to numerous bendings, and consequently, when 
the anterior wall of the belly is laid open, presents the appearance of inextricably 
tangled convolutions. 
From above downward it gradually diminishes in size, thickness of wall, and 
complexity of structure. Its diameter near its beginning is nearly two inches, 
but becomes steadily less, and is hardly an inch at its lower end. Its loss in 
structural elaborateness will be described in detail later on. 
It occupies the umbilical and hypogastric regions and the adjacent portions of 
the lumbar, being to a large extent within the area bounded by the colon. 
Parts of the Small Intestine.—lt is usually described as consisting of three 
parts—the duodenum, jejunum, and ileum. The first of these is limited by 
distinct natural boundaries, and is strikingly different from the rest in other 
respects. The second and third are not thus differentiated, and there is no 
manifest advantage in continuing the attempt to distinguish them from one 
another. But as the names are fastened in our nomenclature, they will be used 
to designate respectively the uppermost and lowermost portions of the small 
intestine distal to the duodenum, without the suggestion of a definite line or even 
region of demarcation between them ; and the name jejuno-ileum will be em- 
ployed to indicate the continuous, undivided whole which the two constitute. 
The small intestine has four tunics, which correspond in general character 
and arrangement with those of the stomach. 
The Serous Coat (Fig. 768) furnishes a practically complete covering for the 
whole tube, excepting the duodenum, which is but 
scantily clad with it. This membrane is reflected 
from the dorsal wall of the abdomen, runs forward 
for a distance, which varies in different parts, reaches 
the intestine, which it closely enwraps, and, returning 
almost to its line of first contact, turns toward its 
parietal origin, keeping in practical apposition with 
its outgoing layer, until it arrives at its starting- 
point, where it is reflected toward the opposite side 
of the body. Thus is formed not only a snug inves- 
titure for the gut, but also a double-layered mooring, 
fastened at one end to the hind wall of the abdomen, 
at the other to the intestine, and permitting large 
freedom of movement. This structure is the mesen- 
tery (“ in the midst of the intestines ”), and between 
its two layers are the arteries, veins, lymphatic ves- 
sels, and nerves required by the bowel, a great 
number of lymph-nodes, and usually a quantity of 
adipose (Fig. 769). The proximal (attached, parie- 
tal, dorsal) border of the mesentery extends from the 
left side of the second lumbar vertebra to the right 
mesocolon, its direction being from above downward and to the right, and its 
measurement eight or ten inches. The distal (free, intestinal, ventral) border is 
vastly longer, being frilled out to the length of the jejuno-ileum, and thus sug- 
gestive of a widely opened fan. Its sides are right or superior, and left or 
inferior. Its length is from the attached to the free border, and varies from one 
inch to ten inches. 
Tunics of the Small Intestine. 
-PREE BORDER 
JEJ U N 0 
ILEUM 
.ATTACHED 
BORDER 
Fig. 768.—Diagram to show the 
relation of the peritoneum (broken 
line) to the greater part of the 
small intestine. 
HIND WALL 
OF ABDOMEN 
The Muscular Coat lies just within the serous, which covers it perfectly, 
except for a very narrow strip between the lines of attachment of the mesenteric 
layers. This bare area marks what is called the attached border of the intestine, THE SMALL INTESTINE. 
719 
and the exactly opposite portion of the gnt is known as the free border. The 
outer layer of the muscular tunic is complete, thin, composed of bundles arranged 
lengthwise, and thickest in the region of the free border. The inner layer, also, 
is complete, but is thicker, and its fasciculi are transverse, forming a circular 
layer. This coat thins out gradually as the intestine approaches its lower end. 
The Areolar Coat.—Inside of the muscular is the areolar (submucous, vascu- 
lar) coat, in whose meshes are networks of blood-vessels, lymphatics and nerves. 
Fig. 769.—A loop of small intestine, showing the mode of distribution of the arteries. 
(Testut.) 
The Mucous Coat.—Finally, we reach the mucous membrane, which is attached 
by its outer aspect to the areolar tunic, and presents a free surface to the bore of 
the tube. Its corium contains lymphoid tissue, with many leucocytes, and a rich 
supply of vessels and nerves. Outside of this is a distinct muscularis mucosae, 
with an inner plate of circular, and an outer plate of longitudinal fibres. Inside 
MOUTHS OF GLANDS 
OF LI EBERKUH N 
SOLITARY GLAND 
Fig. 770.—Free surface of the mucous membrane of the small intestine, showing villi, solitary glands and 
openings of the intestinal glands. Semidiagrammatic. (Testut.) 
of the corium is a basement membrane, surmounted by a single layer of prismatic, 
columnar, epithelial cells, which are characterized by the presence of a delicate 
plate on the free end of each, marked with vertical lines. Among these epithelial 
cells are many of the goblet variety. 
The Villi (Fig. 770).—A peculiarity, which distinguishes the mucous mem- 
brane of the small intestine is the presence everywhere of minute projections, 720 
THE ORGANS OF DIGESTION. 
called villi, which are so abundant as to give a velvety appearance to the surface. 
They are organs of absorption. Their number has been variously estimated at 
from four to ten millions. In the upper part of the intestine they are so closely 
set as to seem to leave no space between. The tallest are scarcely one twenty- 
fifth of an inch in height. In shape they are commonly cylindrical; but conical, 
filiform, mammillary, and lamellar varieties are observed. A lymph-vessel (lac- 
teal) occupies the centre of the villus, a plexus of capillary blood-vessels surrounds 
this, a few threads of smooth muscle run up from the depths of the membrane, 
all these are embedded in a mass of nucleated cells, and the whole villus is cov- 
ered by the columnar epithelium already mentioned. 
The Valvulas Conniventes.—Another feature which characterizes this tunic 
and is observed from an inch or two below the pylorus to within a foot or more 
of the end of the gut, is the presence of transverse folds of mucous membrane, 
each strengthened internally by a projection from the areolar coat. They are 
called valvulce conniventes (“ winking-valves”). Unlike the rugae of the stomach, 
which are effaced when that organ is filled, they are not obliterated by the dis- 
tension of the intestine. This permanency is due to several causes. First, these 
projections are not produced by a wrinkling of the membrane during relaxation, 
as are the ridges of the stomach, but are actual outgrowths of the mucosa, giving 
it.an immense increase of surface, even during distension. Second, the valves do 
not extend completely around the circumference, but only a quarter, half, or 
(rarely) three-quarters way round, one considerably overlapping the lines of its 
next neighbors, and thus guarding against the effacement which might occur 
during extreme stretching, if each of them described a 
complete circle. In other words, an internal pressure, 
which might be able to unfold a perfect ring, is thwarted 
by a device which distributes that force to several sepa- 
rate segments and to a considerable extent of surface. 
And, third, the transverse arrangement of the valves is 
more favorable to their continuance than the longitudi- 
nal would be, as the stretching of the tube from within 
takes place almost altogether laterally and but slightly 
lengthwise, and, consequently, these folds are subjected 
to hardly any strain in these circumstances. 
The valvulse conniventes are somewhat crescentic in 
shape, may be as much as a fourth or third of an inch 
deep in the middle, and diminish in depth toward the 
ends, which often bifurcate, and finally shade off into 
the surrounding surface. There are usually eight or 
nine hundred of them. 
Glands in the Mucosa.—Almost the entire substance 
of the corinm is occupied by tubular depressions, which 
are lined with epithelium, very similar to that on the 
exposed surface, being columnar with frequent inter- 
ruptions by goblet cells. These are the intestinal glands, 
more frequently called the follicles or crypts of Lieher- 
Jcuhn (Fig- 771). Their secretion is chiefly intestinal 
juice, though they furnish also some of the mucus, which is always present. 
Lymph-structures in the Mucosa.—Embedded in the mucous coat and often 
encroaching upon the areolar are little globular or ovoid bodies, one-twelfth inch 
or less in diameter, which are structurally closely related to the lymph-nodes, 
being composed of a multitude of leucocytes, held together by an adenoid reticu- 
lar framework, and drained by lymphatic vessels. They are sprinkled rather 
uniformly throughout the length of the viscus, though in some spots they are 
scarce, in others very numerous. They are the solitary lymph-nodules, but they 
are most frequently called solitary glands (Fig. 772), though no more entitled to 
the name than are the nodes, which occur in the course of lymphatic vessels, 
Fig. 771.—Intestinal gland 
in longitudinal section. (Tes- 
tut.) THE SMALL INTESTINE. 
721 
having no secreting apparatus. We may fairly regard them as the picket-line of 
the great army of nodes, which occupy the mesentery. 
PLANE OF MU- 
COUS SURFACE 
SMUCOUS COAT 
Fig. 772.—Mucosa of small intestine in ideal vertical cross-section. (Testut, after Heitzmann.) 
Having now considered the features common to the whole of the small intes- 
tine, we will study each portion of it in detail. 
THE DUODENUM. 
The duodenum (Fig. 773) dilfers from the jejuno-ileum in many respects. It 
is much wider, thicker in wall, more deeply situated, more complex in structure, 
contains certain glands peculiar to it, and is the part into which the ducts from 
the liver and pancreas discharge ; but it is much shorter, far less mobile, has only 
a scanty serous covering, and has none of the aggregated lymph-nodules. Its 
length is ten inches or less, its width two inches or less. It extends in a tortuous 
course from the pyloric opening to the point where the mesentery first embraces 
the gut, that is, at the left side of the second lumbar vertebra. It is conveniently 
divided into four portions, of which the first, about two inches long, runs back, 
up, and to the right under the quadrate lobe of the liver to the neck of the gall- 
bladder ; the second descends for about three inches along the right edge of the 
head of the pancreas, to the level of the lower border of the third lumbar ver- 
tebra ; the third passes to the left horizontally two inches and a half, which brings 
it to the middle of the vertebral column, where it is crossed by the superior 
mesenteric vessels; and the fourth ascends on the left of the column and ends in 
the jejuno-ileum, which descends from the line of junction very abruptly. Thus, 
the duodenum, after describing an irregular curve, suggestive of an imperfect 
circle, almost returns to its starting-point. 
Its serous coat is incomplete and irregularly applied. The first part is 
covered like the stomach ; the second is clothed in front; the third above, below, 722 
THE ORGANS OF DIGESTION. 
Gastric artery 
Lower end of oesophagus 
Ccdiac axis 
Portal vein- 
Hepatic duct- 
Cystic duct- 
liight suprarenal_ 
capsule 
Hepatic artery- 
Left gastro-epiploic artery 
Duodeno-jejunal junction 
| Superior mesenteric artery 
Eight gastro-epiploic 
artery 
Pyloric orifice- 
Superior mesenteric_ 
vein 
Spermatic vessels 
, Spermatic vessels 
Fig. 773.—The duodenum, its four parts marked a, b, c, d. The liver is lifted up; the greater part of the 
stomach is removed, broken lines indicating its former position, (Testut.) 
Inferior mesenteric artery 
and in front; the fourth in front and partly at the sides. The second part is 
closely adherent to the front of the right kidney and the head of the pancreas, 
LIVER 
GASTRO-HEPATIC 
OMENTUM 
DUODENUM: 
SECOND PART 
duodenum; 
FIRST PART 
INFERIOR 
VENA 
. CAVA . 
RIGHT 
KIDNEY 
GREAT 
OMENTUM 
Fig. 774.—Diagram of cross-section of the first 
part of the duodenum, to show its peritoneal 
relations. 
Fig. 775.—Diagram of cross-section of the second part 
of the duodenum, to show its peritoneal relations. THE SMALL INTESTINE. 
723 
and includes in its wall the terminal portions of the common bile-duct and the 
pancreatic duct; the third part is attached to the vena cava inferior, the aorta, 
and the right crus of the diaphragm ; and the fourth is fastened to the left side 
of the vertebral column, the left kidney and its vessels. The relations of the 
peritoneum to each of the parts of the duodenum will be seen easily by consult- 
ing the diagrams, Figs. 774-777. The first part is somewhat movable, but the 
others are so bound down by the peritoneum and their close connections with 
other structures as to be practically fixed in their places. Still another agency 
contributes to this immobility—the suspensory muscle, a delicate, flat, fibro- 
AORTA, VENA CAVA, 
AND RIGHT CRUS 
DUODENUM; 
FOURTH PART 
DUODENUM*. 
THIRD PART 
SECON D 
LUMBAR 
VERTEBRA 
LEFT 
KIDNEY 
Fig. 776.—Diagram of the third part of the 
duodenum, to show its peritoneal relations. 
Fig. 777.—Diagram of the fourth part of the duodenum, 
to show its peritoneal relations. 
muscular band, which starts from the left crus of the diaphragm, and runs down- 
ward to its insertion on the duodeno-jejunal angle and the dorso-mesial aspect of 
the fourth part of the duodenum. 
The valvulce conniventes are particularly well developed in this bowel. In the 
areolar coat are situated many spheroidal, compound, racemose glands, which 
open upon the free surface. They form an almost complete layer under the true 
mucosa at the upper part of the duodenum. They are peculiar to this portion of 
the small intestine, and hence are called duodenal glands, although they are often 
known as the glands of Brunner. 
About the middle of the concave side of the descending (second) part is the 
common opening of the pancreatic and bile ducts. 
THE JEJUNO-ILEUM. 
The principal features of the small intestine having been presented, the 
jejuno-ileum, which is the main part of it, requires but little special attention. 
Beginning at the termination of the duodenum, it is thrown into convolutions 
so numerous and so irregular in their disposition that it is impossible to lay down 
a rule by which sight alone can distinguish a proximal from a distal portion. 
However, in general there is some probability that its proximal half is located 
above and at the left, its distal below and at the right. 
To determine whether a knuckle of intestine is proximal or distal to another, 
one is assisted by digital examination of the part of the mesentery belonging to 
each. The convolution whose mesentery is the higher is nearer the stomach. 
This method not only is more expeditious, but it prevents the injury which the 
bowels may suffer from prolonged manipulation. 
The last portion of the jejuno-ileum reaches the large intestine from the left 
and below. 724 
THE ORGANS OF DIGESTION. 
The jejuno-ilenm begins with a diameter of nearly an inch and a half, with 
closely set villi, long, deep, and numerous valvulse conniventes, and a fairly 
thick muscular coat; it ends with a cross-measurement of hardly an inch, with 
scanty villosities, no connivent valves, and a thinner musculature. In a single 
direction only has it made a gain—the addition of the aggregated lymph-nodules, 
otherwise called the agminated glands and the patches of Feyer (Fig. 778). These 
Fig. 778.—Aggregated lymph-nodule (Peyer’s patch). (Testut.) 
are local accumulations of bodies in all essential respects like the solitary lymph- 
nodules, which are scattered throughout the length of the small intestine—they 
are colonies of lymph-nodules. They produce scarcely any elevation of the sur- 
face, but are not crossed by connivent valves; they are always situated at the 
free border of the tube, with their greater diameter lengthwise of it; are rarely 
found in the upper half, and become larger and more numerous as the large intes- 
tine is approached ; vary in size from a half inch in both directions to a width 
of about an inch and a length of ten inches, or possibly more ; are thirty or more 
in number on the average ; and tend to disappear gradually after middle life, so 
that in old people they may be recognizable only as areas of discoloration. They 
are the seat of the lesion in enteric (typhoid) fever. 
The blood-supply of the jejuno-ileum is derived from the superior mesenteric 
artery, whose branches course between the two layers of the mesentery, are dis- 
tributed beneath the serous coat, anastomose on the free border, and perforate the 
muscular layers, forming a rich plexus in the areolar tunic, from which the 
mucous and muscular are furnished with their supply of arterioles and capillaries. 
The veins correspond. Ordinary lymphatics, originating in the other parts, are 
joined by those from the villi (lacteals), and leave by way of the mesentery to 
empty into the receptaeulum. 
The nerves come from the superior mesenteric plexus, accompany the vessels, 
and form one network between the layers of the muscular tunic, another in the 
areolar. Their exact terminations are not understood. The duodenum gets a 
part of its arterial blood from the superior mesenteric, and the rest through 
branches of the hepatic. 
THE LARGE INTESTINE. 
The largeness which gives a name to the next grand division of the alimen- 
tary canal is in its transverse, not in its longitudinal, diameter; for it is hardly 
more than a quarter as long as the small intestine, but is much wider, being two 
and a half inches across in its broadest part. 
The large intestine (intedinum crassmnri) (Fig. 779) is divided for description 
into three parts—ctecum, colon, and rectum—and has so little mobility that the THE LARGE INTESTINE. 
725 
location and relations of each of these segments are fairly constant—a respect in 
which it materially differs from the small intestine. 
It begins in the right and lower portion of the abdomen, passes upward and 
backward to the under surface of the liver, thence across the belly to the spleen. 
Fig. 779.—The stomach and intestines, front view, the great omentum having been removed, and the liver 
turned up and to the right. The dotted line shows the normal position of the anterior border of the liver. 
The dart points to the foramen of Winslow. (Testut.) 
from this point downward and forward to the left and lower part of the abdomen, 
here makes a number of curves, and finally plunges into the pelvis at its back 
part, and ends close to the perineum, near the inner opening of the anal canal. 
Tunics of the Large Intestine. 
Its wall is thicker than that of the small intestine. Its tunics are four in 
number, and have the same names and the same order of arrangement as do those 
of the stomach and small intestine. The serous coat of each portion will be 
described in connection with it; the areolar presents no peculiarities requiring 
especial mention. 
The Muscular Coat (Fig. 780) of all but the last few inches of the length is 
remarkable in that its outer, longitudinal layer, instead of being disposed in an 726 
THE ORGANS OF DIGESTION. 
unbroken sheet, as is that of the small intestine, is almost wholly gathered into 
three equal, ribbon-like bands (toenia coli), one-third of an inch, or a little 
more, in width, which are placed length- 
wise at equidistant intervals, the small 
remaining portion being spread in a deli- 
cate lamina over the residue of the tube. 
The inner, circular layer, like the sub- 
jacent areolar and mucous tunics, forms 
an even tube from end to end ; but these 
outer strips of muscle are much shorter 
than this musculo-areolo-mucous tube, 
and, as their extremities are attached to 
its corresponding extremities, there neces- 
sarily ensues a great puckering included 
in their grasp. Between the bands are 
deep, transverse creases, each bounded 
by prominent bulges ; and an inspection 
of the bore of the tube shows a sharp 
ridge {plica sigmoidea), corresponding to 
each depression of the outer surface, and 
MUSCULAR BAND 
INTERIOR OfJ 
SACCULE J 
BAND 
MUSCULAR; 
BAND 
Fig. 780— Segment of large intestine, showing the 
characteristic features of its structure. (Testut.) 
a large recess (haustrum), collocated with each external protrusion. This saccula- 
tion and the cause of it are characteristic. Whenever one is in doubt as to 
whether a given knuckle belongs to large or small intestine, the presence or 
absence of the longitudinal ribbons will settle the question at once. 
Although the ridges, which encroach upon the lumen of this gut, look like 
overgrown valvulse conniventes, their structural character is radically different. 
A connivent valve (Fig. 781) is merely a fold of mucous membrane, strength- 
"mucous coat 
/AREOLAR COAT 
MUSCULAR LAYER 
pEXTERNAL MUSCULAR LAYER 
_SEROUS COAT 
Fig. 781—Diagram to show the structure of the valvulse conniventes. Compare with next cut. (F. H. G.) 
ened by a thin plate of areolar tissue; but a plica sigmoidea (Fig. 782) is the 
result of an infolding of everything inside of the muscular ribbons. Remove 
MUCOUS COAT 
. AREOLAR COAT 
_JNTERNAL MUSCULAR LAYER 
|external MUSCULAR LAYER 
SEROUS COAT 
Fig. 782.—Diagram to show the structure of the plicae sigmoidese. Compare with the preceding cut, 
(F. H. G.) 
these bands from the bowel, and straighten it, and the plicse will disappear, leav- 
ing an even, uninterrupted bore ; but no such result will ensue, if you dissect off 
the longitudinal lamina of muscle from the small intestine : the little valves will 
remain exactly as before. 727 
THE LARGE INTESTINE. 
The mucous membrane is paler, somewhat firmer, and much simpler than that 
of the small intestine ; there are no connivent valves, no villi, no glands of Brun- 
ner, no patches of Peyer. But there are many so-called solitary glands, though 
they are less numerous than in the upper bowel; and the thickness of the mucosa 
is occupied by simple, tubular glands, larger 
than those met with previously, and containing 
a much greater proportion of goblet cells. In- 
deed, in not infrequent cases, it is found that 
the majority of the epithelial cells are of this 
variety. 
THE CJEOUM. 
The caecum {oceans, “blind”) (Figs. 783, 
785) is thus named because it is a pouch, a no- 
thoroughfare, Its blind end points downward, 
its open end upward, passing directly into the 
colon, of which this gut seems to be the begin- 
ning, justifying its old name, caput coll, “ the 
head of the colon.” The line of separation 
between them is at the level of the opening 
from the small intestine, on the left side and 
behind, about two and a half inches from the 
lower end. Here is the ileo-ccecal or ileo-eolic 
valve, which protects the ileum against the back- 
Fig. 783.—Cavity of the caecum, its front 
wall having been cut away. The ileo-csecal 
valve and the opening of the appendix are 
shown. (Testut) 
ward flow of faeces from the large intestine. If the extremity of the ileum was 
simply attached to the margin of a circular hole of its own diameter in the side 
of the large intestine, there would be a frequent reflux from the latter, and the 
COLON 
COAT 
—EXTERNAL LAYER \ MUSCULAR 
LAYER / COAT 
COAT 
COAT 
ILEUM 
CfEC U M 
COAT 
C—AREOLAR COAT 
r' INTERNAL LAYER 1 MUSCULAR 
LA YERj COAT 
COAT J 
Fig. 784.—Diagram of a vertical section of the ileo-csecal valve, showing its structure. (F. H. G.)' 
lower ileum would be only a receptacle for excrement. But, at the junction of 
the two guts, the ileum is flattened from above downward, and the serous coat and 
the outer layer of the muscular coat are so shortened that the other tunics are thrust 
into the cavity of the large intestine, forming two lips, an upper and a lower, with 728 
THE ORGANS OF DIGESTION. 
a horizontal cleft, like a button-hole, between them (Fig. 784). The permanency 
of the lips is maintained by the shortness of the outer muscular layer. The ileum 
enters the large intestine obliquely from below ; and thus, when there is an accumu- 
lation of faeces in the caecum, the two lips will be pressed together, and regurgita- 
tion prevented; but there is nothing in the conformation of the valve to interfere 
with the passage of material in the other direction. From each commissure of the 
lips extends a ridge, which, after going part way round the bowel, shades off into 
the general surface. Upon that aspect of these lips which is contributed by the 
small intestine are villi; that which is furnished by the large intestine is devoid 
of them. 
The Appendix. 
Springing from the rear of the caecum toward its inner aspect is a blind tube, 
about as thick as an ordinary lead-pencil, and varying from three to six (or even 
more) inches in length, called the appendix 
vermiformis cceci (“ the worm-like appendage 
of the blind gut”) (Fig. 785). It has a me- 
sentery for about half its length ; its serous, 
muscular, and areolar coats are similar to those 
of the small intestine; its mucous coat has 
intestinal glands, and so many so-called soli- 
tary glands as to constitute a nearly complete 
layer in and just beneath the mucosa. Its 
attitude varies enormously : it may stand up 
behind the colon, hang down behind the ctecum, 
lie forward toward the surface of the belly, 
curve to the outside, or twine around the ileum. 
Its development is peculiar. The ctecum is 
relatively much longer in the foetal than in the 
adult condition. At birth it is a long cone, 
hardly suggesting the shape which it finally 
assumes. The portion nearest the colon grows 
and develops equally with the latter; but the 
remainder ceases to develop, and, being vastly 
outgrown and overshadowed by the upper por- 
tion, becomes an appendage to what was 
originally the smaller part of the blind gut. 
We see, therefore, that this worm-like organ 
Fig. 785.—The caecum, dorso-mesial view, 
showing the ileum-side of the ileo-caecal 
valve, and the beginning of the three mus- 
cular ribbons. (Testut.) 
has reached its present condition as the result of arrested development, and not of 
degeneration. 
The three ribbons of muscle previously described begin at the attached end of 
the appendix. One runs up close behind the ileo-csecal junction ; another curves 
downward, inward, and then upward on the front; and the third turns downward, 
outward, and then upward. From their position they are called respectively 
postero-internal, anterior, and postero-external. The appendix would be at the 
lowest extremity of the caecum, in the adult as it is in the foetal condition, but for 
the bulging of the front part of the latter downward, and especially outward, a 
change which brings the opening of the appendix behind and toward the middle 
line of the body. 
The caecum has a complete investment of serous membrane, but it has no 
mesentery. 
THE COLON 
The colon comprises all but a mere span of the large intestine. It diminishes 
in size gradually from its beginning to its end. It presents four well-marked THE LARGE INTESTINE. 
729 
segments : the ascending colon, the transverse colon, the descending colon, and the 
sigmoid colon. Its serous membrane is marked at irregular intervals along the 
line of one of the muscular bands by little tassel-like protrusions, the appendices 
epipldicce (“ omental appendages ”), containing adipose tissue. They do not 
appear until after childhood, and arc pronounced in proportion to the fatness of 
the individual. 
The Ascending- Colon. 
The ascending colon (Fig. 786) begins at the level of the ileo-csecal valve, 
passes upward and backward, and ends at the under surface of the right lobe of 
the liver, where it is received in the colic impression. It has no inherent 
peculiarities to distinguish it from other segments except in its serous tunic. 
The disposition of this coat determines the mobility or fixity of the part. Gen- 
erally only the front and sides are clad in peritoneum, which is reflected laterally 
to the abdominal wall; but not very infrequently a distinct mesentery, here 
called ascending mesocolon, is found. In the former case this part is immovable; 
in the latter its mobility is regulated by the length of its mesentery. 
The Transverse Colon. 
The transverse colon (Fig. 786) begins at the hepatic flexure, which is the 
angle made between it and the preceding 
portion, and passes almost horizontally to 
a nearly corresponding point on the left side, 
where it terminates in a bend, the splenic flexure, 
between it and the descending colon. In cross- 
ing the trunk, however, it does not go in a straight 
line, but, keeping close to the anterior wall, 
describes a curve with its concavity backward, 
and displays thrice the length that it would, if 
it ran directly from side to side. It often sags 
a little in the middle. This part of the colon 
is provided with a mesentery, the transverse 
mesocolon, which varies greatly in length in 
different subjects. Its proximal border is 
fastened to the hind wall of the abdomen, its 
distal is attached to the gut along the line 
of the postero-inferior muscular band. The 
antero-inferior band is decorated with appen- 
dices epiploicse, and the superior is the base 
from which depend the hind layers of the great 
omentum. 
Fig. 786.—Ascending and transverse 
colons, viewed from the right side. (Drawn 
from the His cast. F. H. G.) 
The Descending Colon 
The descending colon is almost the exact counterpart of the ascending ; but it 
is a little smaller in bore, a trifle longer—the great thickness of the liver pre- 
venting the ascending colon from reaching quite as high a plane as that from 
which the descending starts—and somewhat farther back in its upper portion. 
It ends at the level of the crest of the ilium—an arbitrary and conventional limit, 
there being no inherent, natural mark of separation between it and the next 
division. Finally, it is hardly ever furnished with a mesentery, and its hind 
surface is generally bare of serous membrane. 730 
THE ORGANS OF DIGESTION. 
The sigmoid colon (Figs. 787-789) is often called the sigmoid flexure; but as 
the term “ flexure ” is used to designate the bends between the horizontal and the 
two vertical portions—mere angles in, and not parts of, the tube—it is confusing 
The Sigmoid Colon. 
to have the same name applied to a por- 
tion of the bowel, which, while the seat 
of complicated flexions, includes a consid- 
erable length of the intestine. “ Sigmoid 
colon ” signifies a part of this intestine, 
whose form is so tortuous as to suggest the 
Fig. 787—Sigmoid colon, front view. Semidiagram 
matic. (Testut.) 
Fig. 788.—Sigmoid colon, dorsal view. 
(Drawn from the His cast. F. H. G.) 
Greek letter sigma, and seems, on the whole, to be the best of its numerous titles. 
The Limits of the Sigmoid Colon.—The sigmoid colon is the most movable and 
the most variable of the divisions of the large intestine. It is continuous below 
with the rectum, and most authors fix the dividing line between the two opposite 
the joint of the left hip-bone with the sacrum. But the result of many careful 
observations shows that, while the large intestine crosses this articulation in some 
cases, in the majority this condition does not obtain. Even if the classical 
description were in accordance with the fact, there would seem to be little wisdom 
in separating these two territories of intestinal surface by this extraneous and 
purely arbitrary boundary, thus depriving the sigmoid colon of a portion of 
intestine exactly like its major part in structure, and bestowing it upon the rectum, 
from which it materially differs. A few recent writers, recognizing the expediency 
of adopting the intrinsic dividing line, which nature has established, have dis- 
carded the extrinsic and artificial boundary, and confine the application of the 
name “ rectum ” to that portion of the bowel below the brim of the true pelvis 
which has no mesentery. This method is here adopted. 
The sigmoid colon (Fig. 787) begins on the plane of the crest of the left 
ilium, and thence usually passes down to within an inch and a half of the inguinal 
(Poupart’s) ligament, bends sharply toward the middle line, crosses the psoas 
magnus muscle, dips into the cavity of the true pelvis, rises to the brim on the 
right side, and thence curves backward, downward and inward to about the third 
sacral vertebra at the median line, where it becomes continuous with the rectum. 
It is 14 or more inches long. For its uppermost three inches it has a serous 
covering on its front and sides only ; but below this it has a mesocolon in its 
entire length. The sigmoid mesocolon is much longer in the middle portions than 
toward the ends. The diameter of this part of the intestine is less than that of 
the preceding, and constantly, though gradually, diminishes toward its lower end. 
The three longitudinal bands are continued on the sigmoid colon for most of its 
course ; but, as the end is approached, those which are behind spread out and THE LA RGE INTESTINE. 
731 
Fig. 789.—Sigmoid colon and rectum, front view. The broken lines indicate the situation of the con- 
cealed part of the sigmoid colon. The small intestine is drawn away, and the anus is turned forward. (Testut.) 
EXTERNAL ILIAC ARTERY 
EXTERNAL ILIAC VEIN 
ANTERIOR CRURAL NERVE 
vaginae 
F E M O RIS 
SCIATIC NERVE 
INFERIOR GLUTEAL ARTERY1 INTERNAL PUDIC ARTERY 
Fig. 790.—Horizontal section three inches below the sacral promontory. The upper surface of the lower 
segment. (Testut.) 732 
THE ORGANS OF DIGESTION. 
unite into one, and at the last part the anterior lias extended sidewise, and joined 
its fellows, so that the rectum begins with a uniform outer layer of its muscular 
tunic. 
The rectum (Figs. 791, 792) begins at the point where the large intestine 
ceases to be provided with a mesentery, that is, in general, at the front of the 
third sacral vertebra in the middle line. Its name, which means “ straight/7 is 
THE RECTUM. 
LEFT COMMON 
ILIAC VEIN 
made less absurd by the adoption of our present plan of delimitation of the intes- 
tines in this region, than it was when this segment was made to start at the sacro- 
iliac joint; for then it was crooked from every point of view, while now, when 
looked at from in front, it comes near deserving its title. 
It occupies the middle line, and is divided into an upper part, which is fur- 
nished with a covering of peritoneum, and a lower, which is not. The upper 
part, about three inches long, extends from the third sacral vertebra to the tip of 
the coccyx, and its shape conforms to the curve of these bones, to which it is 
attached behind. The lower part, shorter than the upper, is continued with the 
same dorsoventral curve, and terminates in a forward pouch, which is close to the 
prostate gland in the male and to the lower part of the vagina in the female. 
Fig. 791.—Sagittal section of the lower part of a male trunk, the right segment. (Testut.) THE LARGE INTESTINE. 
733 
If the lower opening of the alimentary canal were made at the end of this 
pouch, and in the line of its curve, the anus would be situated in the male just 
back of the attachment of the scrotum and in the female near the vaginal entrance. 
The curve of the rectum, thus extended, would present an even sweep from its 
CLITORIS—^ 
Fig. 792.—Sagittal section of the lower part of a female trunk, right segment. (Testut.) 
upper to its lower end. The opening, however, is not thus placed, but is located 
in the under side of the rectum, considerably to the rear of its blunt end. The 
part of the intestine in front of this opening is called the rectal ampulla. 
The muscular coat is thick and strong at all points, and consists of two layers, 
the external being the longitudinal, the internal the circular, and both evenly 
spread. 
The serous tunic covers only a portion of the first part, and none of the second. 
This coat is most extensive in front, and is absent behind; and the line at which 
it leaves the gut slopes from above downward and forward very rapidly. It is 
reflected onto the bladder in the male, and the vault of the vagina and the uterus 
in the female. Where there is no serous coat the rectum is covered with strong 
areolar tissue. 
The mucous membrane is thicker and denser than that of the colon, and its hue 
deepens to a decided red in the lower part. It usually presents from one to three 
transverse folds, plicce recti, which may go a third of the way around the lumen, 734 
THE ORGANS OF DIGESTION 
and are thought to be permanent. At the margin of the opening from the rectum 
to the anal canal are five or six small crescentic loops, semilunar valves (Fig. 793), 
RECTUM 
ANAL 
column" 
BULGES OF HEMOR-: ANAL ISEMILUNAR VALUE 
RHOIOAL VEINS CANAL 
Fig. 793.—The anal canal and lower part of the rectum, laid open. (Testut.) 
separated by vertical ridges, the anal columns, upon which are little protrusions 
due to hemorrhoidal veins. 
THE ANAL CANAL. 
The anal canal (Figs.79l-793) is the channel by which the rectum is placed in con- 
nection with the external surface of the body. It is an inch long, and runs down- 
ward and backward. It is lined with a membrane, which is mucous at the upper 
end, cutaneous at the lower, and a cross between the two elsewhere. Outside of 
this lining is an embracing muscle, the internal sphincter, composed of bundles 
of smooth fibres, arranged circularly. The lateral walls of the tube are in con- 
tact, and the lining membrane is disposed in small, longitudinal folds. The 
distal aperture is the anus, and around it the skin is dark brown, and puckered 
in radiating lines. 
GLANDS ACCESSORY TO THE ALIMENTARY TUBE. 
In the development of the digestive canal bud-like processes grow out from 
it at several points, and ultimately become glands, furnishing abundant secretions, 
which are discharged into the tube through ducts. These glands are the sali- 
vary, the pancreas, and the liver, and they will now be considered in the order 
given. 
The salivai is a compound fluid, resulting from the mixture of the secretions 
of a number of glands, which discharge their products into the mouth. There 
are many mucous glands, two collections of which on each side require mention. 
One is at the hind part of the oral portion of the tongue, at the side and below, 
and is called the gland of Weber (Fig. 794, gl. w.). The other is beneath the 
lateral border of the tongue near the tip, and is known as the gland, of Blandin 
(Fig. 794, gl. b. and Fig. 758). The so-called salivary corpuscles are derived 
from the tonsils. But the great volume of the saliva is furnished by three pairs 
of glands—the parotid, the submaxillary, and the sublingual. Of these the first 
THE SALIVARY GLANDS THE LARGE INTESTINE. 
735 
produces a watery (serous) secretion, the third a glairy (mucous) one, and the 
second a fluid which is between the two in consistency. 
PAROTID 
DUCT 
Fig. 794.—The salivary glands. The right half of the body of the mandible has been removed 
gland of Weber. GL. 8., gland of Blandin. (Testut.) 
gl. w„ 
The Parotid Gland. 
The parotid (“near the ear”) gland (Fig. 794) is the largest salivary gland, 
and is situated in the side of the face, extending from the zygoma to the angle of 
the mandible, and from the external auditory meatus forward upon the raasseter, 
dipping deeply between the ramus and the mastoid, and pushing in between the 
pterygoid muscles. It is bound down by the masseteric fascia. The parotid 
(Stenson’s) duct, by which the saliva is discharged, leaves the gland at its front 
border, and passes forward horizontally about three-quarters of an inch below the 
zygoma for two and a half inches. On reaching the anterior margin of the mas- 
seter, it turns mesially, and perforates all of the buccal layers, except the mucosa, 
on the outer surface of which it then courses forward until it reaches a point 
opposite the second upper molar tooth, where it pierces the membrane, and ends 
in a contracted orifice. Usually an appendage, the glandida soda parotidis, lies 
above the first part of the duct, and pours its secretion into it. 
In the substance of the parotid gland the external carotid artery makes its 
terminal division, the facial nerve radiates into its branches, and the temporo- 
maxillary vein, some lymph-nodes, and branches of the great auricular nerve 
are situated. 
The Submaxillary Gland. 
The submaxillary gland (Fig. 794) is about a third as large as the parotid. 
It is lodged in a chamber of the deep cervical fascia, mostly below the body of 736 
THE ORGANS OF DIGESTION. 
the mandible, and upon the mesial side of its angle. The stylomandibular liga- 
ment runs between it and the parotid. The facial artery grooves its back and 
upper border. The submaxillary duet (Wharton’s) is two inches long, runs for- 
ward and inward beneath and mesial to the sublingual gland to the side of the 
franum linguse, where it ends in a constricted orifice, close to its fellow of the 
opposite side. 
The Sublingual Gland. 
The sublingual (Fig. 794) is the smallest of the salivary glands. It lies in the 
gutter between the side of the tongue and the mandible, forming a long elevation 
beneath the mucous membrane of this part of the floor of the mouth. It has 
twenty or less ducts, which open for the most part directly above the gland, a few 
perhaps into the duct of the submaxillary. 
Structure of the Salivary Glands.—All of the salivary glands are of the com- 
pound racemose variety. They consist of lobules, which are held together by a 
variable amount of areolar tissue. Each lobule is an aggregation of acini 
(“ grapes ”) or alveoli, which are the globular or tubular sacs, constituting the 
active part of the organ. These sacs are so nearly filled with secreting epithelial 
cells that the central channel is extremely small. The ducts nearest the acini 
are the radicles of the great stem which finally emerges from the gland. 
THE PANCREAS. 
The pancreas (“all flesh”) (Figs. 795, 796) so closely resembles the parotid 
that it is sometimes called the abdominal salivary gland. In some lower animals 
it is known as the sweetbread. It lies across the front of the first and second 
i DUODENUM ’ 
i\ TRANSVERSE 
U COLON I 
\\ SEVEREDJ 
JEJUNUM 
PERITONEUM 
\ OVER 
\ LEFT 
%KIDNEY . 
DESCENDING 
COLON 
Fig. 795.—The pancreas, ventral view. The superior mesenteric vessels are seen at the lower part of the 
head. (Drawn from the His cast. F. H. G.) 
lumbar vertebra, and behind the stomach. It is covered anteriorly by the upper 
of the two layers, which go to form the transverse mesocolon. Its numerous 
lobes are held together so loosely that the whole mass is flabby, and can easily be 
moulded into shapes which are only remotely suggestive of the normal, which 
was not known until revealed by modern methods. It is a body of irregular 
form, flattened from before backward, and curved from right to left over the ver- 
tebral column. We recognize anterior and posterior surfaces of considerable 
extent, a very narrow upper surface, a lower border, and right and left extremi- 
ties. Its right end spreads out into a head, which fills the curve of the duodenum, 
to which it is firmly attached. Its left extremity is the tail, and reaches into the 
left hypochondriac region, even to the spleen. The intervening portion is the THE LARGE INTESTINE. 
737 
body, and on its hind surface is marked off from the head by a vertical depression, 
sometimes called the neck, in which are lodged the portal vein and the superior 
mesenteric vessels. All of the pancreas except the head is quite movable. 
The color of the gland is pinkish, its weight between two and three ounces, its 
COLON / ' 
DUODENUM 
Fig. 796.—The pancreas, dorsal view. The head is seen in the embrace of the duodenum. The portal vein 
and superior mesenteric artery he behind the neck. (Drawn from the His cast. F. 11. G.) 
length about six inches, its breadth two inches, and its thickness about half an inch. 
In infancy and early youth it grows rapidly, and in old age it undergoes atrophy. 
The Structure of the Pancreas (Fig. 797).—Structurally it is a compound 
acinous gland, consisting of minute tubes, coiled up in little masses, called lobules. 
These are bunched together into lobes, and all the parts are 
held in more or less close relation to one another by 
areolar tissue, which spreads out over the surfaces every- 
where, and is also continuous with that of the immediate 
neighborhood. 
The secretory cells are commonly short cones, whose 
apices point toward the lumen of the tube. Besides these 
are certain cells of spindle-shape, lying against the free 
ends of the first mentioned, and protruding into the bore 
—called the centro-acinous cells. 
The excretory ducts at their beginning are fine tubes, 
consisting of a single layer of flattened epithelium, and 
lying in the delicate connective tissue. The union of 
these forms larger ducts, and these in turn join to make 
those of greater size, until a single great channel, the 
Fig. 797.—Cross section 
of pancreatic acini. (Testut.) 
pancreatic duct, results. As the tubes increase in size, a fibrous coat is added 
outside of the epithelial, and this is thickest in the largest ducts. 
The pancreatic duct (Fig. 798) runs from the tail to the head, in the very 
centre of the gland, and then bends downward, leaves the pancreas, enters the 
wall of the duodenum in the concavity of its second portion, unites with the com- 
mon bile-duct, and the compound duct perforates the mucous membrane. An 
accessory duct is usually found, springing from the main duct at about the neck 
of the gland, and emptying into the duodenum an inch above the other. 
Development.—The pancreas begins in the embryo as a sprout from the intes- 
tine, and this initial tube and its branches become the ducts of the mature organ, 
the true gland tissue budding from these little stalks as leaves form upon a twig. 
The vessels follow the interlobular connective tissue, and, as in all glands, are. 
supplied as capillaries to the secreting organism. 738 
THE ORGANS OF DIGESTION. 
The arteries of the pancreas are branches of the splenic and hepatic, and the 
inferior pancreatico-duodenalis from the superior mesenteric. Its nerves come 
from the solar plexus. 
ar 
//HEPATIC 
f DUCT 
CYSTIC DUCT- 
Str*'c „Rr 
llilf fit 
COMMON BILE DUCT— 
ORIFICE OF AC- 1 
CESSORY PANCRE- f' 
ATIC DUCT ) 
ORIFICE OF BILE) 
AND PANCRE- f 
ATIC DUCTS ) 
Sr-SUP. MESENTERIC 
ARTERY 
Fig. 798.—Ducts of the pancreas. Part of the front wall of the duodenum is cut away. (Testut.) 
THE LIVER. 
The largest and most complex of the appendages of the alimentary tube is the 
liver (hepar). Starting as a bud from the duodenum in the second week of 
embryonic life, it grows with such rapidity that by the second month its weight 
is one-third of that of the entire body. Though not retaining this relative magni- 
tude, it remains as the greatest gland of the body, and the most intricate. 
PHYSIOLOGICAL ANATOMY OF THE LIVER. 
Physiologically considered it is a community of minute livers, all substantially 
alike; and thus a comprehension of one of them is sufficient to put us in posses- 
sion of the anatomical facts requisite for understanding the functions of the entire 
system. 
We are assisted in our study of the liver by comparing it to a great manu- 
facturing town, made up of a vast number of establishments, each of which is 
identical with every other in its organization, size, facilities for work, and the 
quality and quantity of its products. Formerly it was supposed that the only 
service of the liver was the formation of bile ; and although it is now known that 
the secretion of this fluid is only one of several offices performed by this organ, 
it is convenient for our present purpose to take bile-making as the type and 
representative of the entire group of functions. 
A Typical Lobule. 
We will begin by studying a single factory, that is, a separate lobule of the 
liver. It is an irregular, polyhedral body, a twelfth of an inch or less in diameter. 
As in every other true gland, the secreting cells are the essential part of the THE LIVER. 
739 
lobule, and of these there is a multitude, packed together so closely that only 
enough room is left between them to permit the passage of the minute vessels and 
nerves. The hepatic cells are the workmen of the factory. To them the materials 
out of which they are to make bile are brought in the blood of the portal vein. 
Unlike veins generally, the portal divides into a vast number of branches, and a 
network of these encloses the lobule. From these embracing vessels, which are 
very minute, capillaries are sent inward between the cells of the lobule in such 
abundance that each cell is surrounded by them, and is thus plentifully supplied 
with blood containing the raw materials which the cell is capable of working over 
into a new product, the bile. The cells having abstracted the stulf which they 
require in their manufacturing processes, the blood passes on, and, at the centre of 
the lobule, to which point all of the capillaries converge, it enters a vein which 
runs perpendicularly to the course of the peripheral vessels, and carries the blood 
away from the lobule. 
Beginnings of the Bile-ducts.—The surfaces of the cells are grooved in such a 
manner that the gutters on the adjacent surfaces of two cells fit together and 
make a cylindrical channel; and into this passage-way, which may be regarded 
as a drain-pipe, the bile is poured as soon as it is formed by the cell. These 
channels form a network among the cells throughout the lobule, as intricate as 
the plexus of blood-vessels; and from this network the bile is discharged into 
ducts, which ramify abundantly upon the surface of the lobule. 
The Supply of Nutrient Blood.—When we remember that the blood furnished to 
the lobule by the portal vein is venous, we perceive that, however rich it may be in 
the materials necessary for the making of bile, it is not adapted to the nourishing 
of the lobule ; it does not contain the substances needed for the repair of the factory 
or the feeding of the operatives. These nutritious and restorative matters are 
furnished by a separate vessel, the hepatic artery, which sends to each lobule 
branches which course over its surface and give off capillaries inward between 
the cells; and thus another plexus is formed in the lobule. There is not, how- 
ever, a separate vein devoted to the task of removing from the lobule the blood 
introduced by the branches of the hepatic artery : its capillaries enter the plexus 
of portal-vein capillaries near the centre of the lobule, and the hepatic-artery 
blood mingles with the venous, flowing out with it through the central, per- 
pendicular vein. 
Lymphatics.—Besides the materials of various kinds which are carried away 
from the bile-factory by the channels already mentioned, there are certain uncon- 
sumed nutritious substances and certain waste products, which are removed by 
lymphatic vessels. These originate in irregular spaces in the lobule, form a net- 
work around it, and their current is in the direction of the stream of outflowing 
bile, that is, toward the portal at which the blood is introduced into the liver. 
Finally, there are nerves by which a regulation of the different processes is effected 
and harmony maintained among them. 
Arrangement of the Vessels. 
As previously remarked, the lobule is physiologically a minute liver—it is 
the hepatic unit; and the liver itself is merely an enormous aggregation of count- 
less lobules, packed together as solidly as is consistent with the presence of the 
numerous tubes required for its nutrition and the performance of its work. But 
this intimate association of a multitude of lobules necessitates some modification 
of the description which has been given of a single one. The branches of the 
portal vein and of the hepatic artery, and the radicles of the bile-ducts and 
lymphatics, all of which have been described as ramifying upon the outside of 
the lobule, are seen, when the lobules are packed together, to be between the 
lobules ; for the close approximation of a number of lobules brings the networks 
of vessels on the surface of each in contact with the similar plexuses on the sur- 
faces of all of its immediate neighbors. Thus, one set of vessels can be made to 740 
THE ORGANS OF DIGESTION. 
supply the lobules on both sides of it, as easily as upon one side, and this is exactly 
what obtains. As the vessels are between lobules, they receive the name imply- 
ing this, interlobular ; the capillary networks inside of the lobule are called intra- 
lobular (“ within the lobule ”), and the same name is applied to the central vein 
which carries away from the lobule the blood which is brought to it both by the 
portal vein and by the hepatic artery 
(Fig. 799.) The intralobular veins in 
a given region discharge into a very 
much larger vein, upon whose outer 
surface rest a vast number of lobules ; 
and, therefore, the name sublobular 
(“ under the lobule ”) is given to this 
kind of veins. These last empty 
into still larger veins, the hepatic, the 
greater part of them converging to a 
few large trunks, which terminate in 
the inferior vena cava, where it lies 
embedded in the posterior surface of 
the gland, and the remainder of them 
reaching the same destination directly. 
Thus it is seen that the blood 
which enters the portal vein and passes 
through the liver, by way of any 
lobule, must traverse the following 
vessels in succession : portal vein, 
interlobular vein, intralobular capil- 
lary plexus, intralobular vein, sub- 
Fig. 799.—Hepatic lobule in transverse section, show- 
ing the distribution of its blood-vessels, a, a, interlobu- 
lar veins; b, intralobular vein ;c,c, c, plexus of capillary 
blood-vessels within the lobule; d, d, twigs of interlobu- 
lar vein, passing to the adjacent lobules. (Dalton.) 
lobular vein, hepatic vein, inferior vena cava. The nourishing blood passes by 
way of the following vessels : hepatic artery, interlobular artery, its own intra- 
lobular capillaries, portal intralobular capillary plexus, intralobular vein, sub- 
lobular vein, hepatic vein, inferior vena cava,—its course beyond its own plexus 
being identical with that pursued by the portal blood. 
The Hepatic Cells, which are the essential elements in the lobule,—the active 
workers in the bile-factory—are irregular bodies, with flattened sides, and each 
measures about one thousandth of an inch in diameter. They are composed of 
granular protoplasm, have no cell-wall, but each has a single, clear, central 
nucleus. 
The Form of the Liver. 
Although the liver is a solid organ, its consistency is not sufficient to prevent 
its changing its shape materially when it is removed from the body. If placed 
upon a board, its weight so causes it to sprawl in different directions as to pro- 
duce an exaggerated idea of its lateral and antero-posterior dimensions, and an 
inadequate conception of its greatest thickness. When it is made to rest upon 
its upper surface, its mass sags to such an extent that the proper distinction 
between its inferior and posterior surfaces is obliterated, and the two seem to be 
one. To obtain a correct view of the liver, it should be hardened by some pro- 
cess while in its natural relations with contiguous organs. The pictures of its 
surfaces here given have been drawn from a cast of a liver frozen in situ. If the 
student will but remember that the vena cava inferior, which is for some inches 
actually embedded in the liver, always pursues a substantially perpendicular 
course, he will have no difficulty in seeing that the part of the viscus containing 
this great vessel must be behind and not beneath. Vesalius, the father of modern 
anatomy, described and figured the posterior surface in his great folio of 1555; 
but the correct view was lost sight of, and the grossly perverse presentation has 
been allowed to pass muster without question until very recent years, and even 
now the hind surface is not universally recognized. THE LIVER. 
741 
The liver is located in the uppermost part of the abdomen, immediately 
beneath the diaphragm, and more on the right than on the left. 
RIGHT LOBE 
LEFT LOBE 
Fig. 800.—The liver, front view. (Drawn from the His cast. F. H. G.) 
The liver has three surfaces : an upper, or superior, an under, or inferior, and 
a hind, or posterior; three borders, an anterior, a postero-superior, and a postero- 
inferior ; and two extremities, a right, and a left. 
RIGHT LOBE 
LEFT LOBE 
VENA 
CAVA 
INFERIOR 
Fig. 801.—The liver, upper surface. (Drawn from the His cast. F. H. G.) 
The Surfaces of the Liver. 
The Upper Surface (Fig. 801) is smooth, and is applied evenly to the under 
surface of the diaphragm from the extreme right side to about half way between 742 
THE ORGANS OF DIGESTION. 
the middle line and the left abdominal wall. This surface, consequently, is 
markedly convex on the right, slightly concave near the middle of the body, 
where the heart causes a sagging of the diaphragm, and moderately convex at 
the left. It is covered with serous membrane—a reflection of the peritoneum 
—excepting a very narrow strip running from before backward, and marking the 
line along which the membrane from the right side and that from the left meet 
and turn upward, and form the suspensory ligament, which thus divides the 
upper surface into two very unequal parts, a right lobe of extensive area, and a 
left lobe, which is much smaller. This division of the liver into right and left 
portions is observed on the hind and under surfaces also, and is made by a con- 
tinuation upon them of the line marked out by the suspensory ligament. Thus, 
if a cord is carried directly around the organ in this plane, it will nearly coincide 
on the under surface with the umbilical fissure, and on the hind surface with the 
ductus-venosus fissure. On these surfaces, however, all of the right portion is 
not called right lobe, for certain subdivisions are recognized, upon each of which 
distinctive titles have been bestowed. 
The Under Surface (Fig. 802) is very irregular and unevenly concave. It is 
divided into right and left portions by a groove, which, beginning at a notch in 
the anterior border, runs backward on a line substantially beneath the attachment 
right lobe 
,fT_LOSp 
IMPRE9SIOn\ 
OF CARDIAC 
END OF 
STOMACH 
IMPRESSION 
OF KIDNEY 
OMENTAL 
TUBEROSITY ;; 
IMPRESSION OF 
HEPATIC FLEX- 
URE OF COLON 
QUAD- 
RATE 
LOBE 
GALL \ 
BLADDER \ 
Fig. 802.—The liver, lower surface. (Drawn from the His cast. F. H. G.) 
of the suspensory ligament on the upper surface. This groove gives lodgment to 
the shriveled remains of the umbilical vein—an important foetal structure—from 
which fact it is named the umbilical fissure. The part of the surface at the left of 
this crease is the lefit lobe; that at the right is subdivided into three lobes, by two 
grooves. Near the hind edge of this surface is a broad gutter, which runs later- 
ally from and at a right angle to the umbilical fissure; and from the right end 
of this a wide, shallow depression runs to the anterior border, parallel to the 
umbilical fissure. The first of these is called the transverse fissure, from its 
lateral direction ; the portal fissure, from its being the opening or doorway at 
which vessels, ducts, and nerves pass into and out of the viscus ; and sometimes 
the hilum, a name often given to similar inlets in other glands. The second 
groove is named the gall-bladder fissure, from the reservoir of the bile, 
which occupies it. Between the umbilical fissure at the left, the portal fissure 
behind, the gall-bladder fissure at the right, and the anterior border in front, is a 
squarish area, which is called the quadrate lobe, from its shape. At the right of THE LIVER. 
743 
tlie gall-bladder fissure is a large, uneven area, the right lobe. Behind the left 
portion of the portal fissure appears the lower edge of the Spigelian lobe, the 
main portion of which is visible only from behind. Finally, a narrow ridge 
behind the portal fissure connects this inferior border of the Spigelian lobe with 
the right lobe, and is dubbed the caudate lobe, from its fancied resemblance to the 
tail of an animal. About one-half the area of the right lobe at the front and 
right is notably concave and receives the hepatic flexure of the colon. At the 
left of this, and obliquely behind the gall-bladder, is a small impression in which 
a knuckle of the duodenum is located ; and behind both of these areas is a some- 
what rhomboidal hollow which is occupied by the upper end of the right kidney. 
A considerable part of the surface of the left lobe is concave and fits the bulging 
fundus of the stomach ; but there is a prominent protuberance at the right and 
behind (the tuber omentale) against which lie the gastro-hepatic omentum, and 
the smaller curvature of the stomach. 
The Hind Surface (Fig. 803) presents two parallel, vertical grooves : one, 
narrow and shoal, connecting the umbilical fissure of the under surface with the 
VENA 
SITE OF LEFT 
LATERAL LIGAMENT 
LEFT 
SPIGELIAN LOBE 
LOBE 
RIGHT 
LOBE 
CAVA 
INFERIOR 
SITE OF RIGHT/** 
LATERAL LIGAMENT 
Fig. 803.—The liver, posterior surface. A part of the under surface is seen from the rear view, and this is 
shown merely in outline. (Drawn from the His cast. F. H. G.) 
posterior end of the space between the two layers of the suspensory ligament on 
the upper side, and containing the shrunken remnant of the ductus venosus of 
foetal life; the other, broad and deep, corresponds to the gall-bladder fissure of 
the under side, at the lower end is separated from it only by the breadth of the 
caudate lobe, and furnishes a spacious lodging for some inches of the vena cava 
inferior. These fissures are known by the names of the structures which are 
embedded in them. Between them lies a rectangular space called the Spigelian 
lobe, whose lower margin is seen on the inferior surface, and whose upper edge is 
visible from above. At the right of the vena-cava fissure is the large, convex 
right lobe; and at the left of the ductus-venosus fissure is the left lobe, small in 
extent, somewhat triangular in shape at the right, and rapidly tapering at the left 
and becoming a mere margin, which is directly continuous around the left extremity 
of the liver with the anterior border. 744 
THE ORGANS OF DIGESTION. 
Borders of the Liver. 
The Anterior Border separates the upper and under surfaces in front. It is 
thin, sharp, and bevelled at the expense of the inferior surface. It is con- 
tinuous around the right and left extremities of the viscus with the postero- 
inferior border. It is slightly notched at the beginning of the umbilical fissure, 
and more widely so where the gall-bladder touches it. 
The Postero-inferior Border separates the hind and under surfaces. It is well 
defined, except upon the left lobe between the Spigelian lobe and the place where 
the posterior surface is lost in the margin. 
The Postero-superior Border, that between the hind and upper surfaces, is 
marked far less distinctly than the others by any conformation of hepatic sub- 
stance. At the left of the vena cava the upper end of the Spigelian lobe and a 
ridge from it to the beginning of the posterior margin indicate sufficiently the line 
of separation ; but on the other side of the vein the dome-like superior surface 
of the right lobe slopes without break to the back of the organ. There is, 
however, a line along which the serous covering of the upper surface is reflected 
to the hind wall of the abdomen—a line seen with equal distinctness from above 
and from the rear—and this is taken as the natural delimitation of the surfaces 
in question. 
The Extremities of the Liver. 
The Right Extremity is massive, evenly convex above, and terminated below 
by a sharp edge, which is bevelled at the expense of the under surface. 
The Left Extremity is thin, flattened horizontally, convex above, concave 
below, and margined by a very distinct edge. 
Tunics of the Liver. 
The liver is closely invested by a delicate areolar membrane, which is reflected 
inward at the portal fissure upon the vessels and ducts passing through this open- 
ing, and encloses them even to their interlobular ramifications. This wrapping 
of the hepatic tubes is known as the capsule of Glisson. It is not found in con- 
nection with any vessels of the hepatic vein series, because it ceases between the 
lobules, and at least half of the diameter of each of these bodies intervenes 
between the interlobular space and the intralobular vein, which is the initial root- 
let of the system of hepatic veins. These last vessels are, as it were, channeled 
in the substance of the liver, and are so intimately adherent to it that, unlike 
most veins, they show no tendency to collapse, when cut across. The walls of 
the branches of the portal vein, on the other hand, tend to fall together when 
severed, the investment of areolar tissue not holding them open. The fibrous 
coat of the liver is most distinct at the areas over which there is no serous mem- 
brane. 
Like most other organs in the abdomen the liver has a serous tunic, derived 
from the peritoneum. From the small curvature of the stomach there passes to 
the portal fissure the double peritoneal layer which is known as the gastro-hepatic 
omentum, one layer coming from the front, the other from the hind surface of 
the stomach. The anterior of these spreads out upon the under surface of the 
liver, turns up over the anterior border and the two extremities, and then covers 
the upper surface, except small areas at the back edge of the right and left lobes, 
and except, also, where the membrane which comes from the right end meets that 
from the left. Here a very narrow strip of surface, widening into a triangular 
area behind, is left bare ; and on each side the membrane is reflected upward to 
the diaphragm, on reaching which the layers turn to the right and left respect- 
ively, and line its under surface. This double membrane is prolonged forward 
and downward to the anterior abdominal wall as far as the navel, and in the free 
edge (the hind border) of the part of it below the liver is included the obliterated THE LIVER. 
745 
umbilical vein. Thus is formed the suspensory ligament, a sickle-shaped struc- 
ture, with the round ligament in that part of its cutting edge which projects 
beyond the anterior border of the 
liver (Fig. 804). 
The posterior layer of the gastro- 
hepatic omentum spreads out upon 
the hind surface of the liver, but 
does not nearly cover it, the back of 
the right lobe being entirely bare. 
This layer is reflected onto the rear 
wall of the abdomen, along an irreg- 
ular line, extending from just above 
the lower end of the right lobe be- 
hind, along the postero-inferior bor- 
der to the vena cava, in front of this 
vessel, up by its left side, and then 
on the upper surface of the left lobe 
slightly in front of its posterior mar- 
gin, thus constituting the lower por- 
tion of the coronary ligament. The 
upper portion of this large ligament 
LIVER 
NAVEL 
ROUND LIGAMENT 
Fig. 804.—Diagram to show the relations of the sus- 
pensory and round ligaments to the liver and the abdom- 
inal wall. (F. H. G.) 
is made by the corresponding reflection of the serous membrane from the upper 
surface. 
Supports of the Liver. 
The liver is held in place by various agencies. Probably the most important 
of these is its intimate connection with the vena cava inferior. This great vessel, 
passing upward to the heart, is closely adherent to the back wall of the abdomen, 
is deeply lodged for some inches of its upper portion in the substance of the liver, 
and receives from this viscus the few great and many small hepatic veins, some 
of which come to it from a distance of nearly two inches. The support afforded 
by the underlying hollow viscera—the stomach and bowels—is not to be ignored. 
Usually these are occupied to a considerable extent by gas, and thus act as a sort 
of air-cushion upon which their bulky associate can repose. The fibrous cord, 
which results from the atrophy of the umbilical vein of intrauterine life, and is 
known as the round ligament of the liver, does its share in holding up the organ. 
Its upper part is firmly fastened in the umbilical fissure, from the front end of 
which it passes down, close to the anterior abdominal wall, enclosed in the free 
edge of the falciform ligament, and terminates in the navel, with the cicatricial 
tissue of which its end is fused. Finally, there are four ligaments formed by 
folds of peritoneum. Of these the superior has already been described in connec- 
tion with the serous tunic. It is called suspensory, because the liver seems to 
hang from it; broad, in comparison with its fellows ; and falciform, from its 
resemblance to the blade of a sickle. The coronary ligament is so named because 
it encloses or crowns an area, which results from the backward reflection of the 
serous covering of the upper and under surfaces to the hind walls of the abdo- 
men. This ligament is short, and its two layers come together at the right and 
also at the left. Just beyond each of the points of junction of these layers and 
continuous with them there is a small, triangular, double fold of peritoneum, 
which lies between the liver and the diaphragm, and can be best seen by drawing 
the adjacent side of the muscle away from the viscus. These are the lateral liga- 
ments, the right and the left. 
The vessels of the liver are the portal vein, the hepatic artery, the hepatic 
veins, and the lymphatics. The first two of these pass from between the layers 
Vessels of the Liver. 746 
THE ORGANS OF DIGESTION. 
of the gastro-hepatic omentum into the liver at the transverse fissure, their 
branches are embraced by the capsule of Glisson, and they are distributed as has 
been already stated, the one contributing material upon which the hepatic cells 
are to act, the other furnishing nourishing blood to the various structures of the 
liver. The hepatic veins receive the blood from the capillaries both of the portal 
vein and the hepatic artery, and discharge it into the ascending vena cava. 
The lymphatics of the liver are both deep and superficial. The deep are 
divided into a set associated with the portal vessels, and a set accompanying the 
hepatic veins. The former emerge through the portal fissure, and pass through 
the hepatic nodes on their way to the coeliac ; the latter empty into the vena- 
caval nodes. The superficial lymph-vessels of the under surface are tributaries of 
the hepatic nodes, while those from the upper aud hind surfaces drain into the 
anterior mediastinal and vena-caval. 
The nerves of the liver are derived from the left pneumogastric, and from the 
solar plexus, the latter being distributed mainly to the hepatic artery, though to 
some extent to the portal vein. 
The Bile-ducts. 
The minute, intralobular bile-channels empty into delicate interlobular tubes, 
lined with very thin cells, which are continuous with the bile-secreting cells. 
These ducts unite and form larger tubes, lined with columnar epithelium, and 
constitute an interlobular plexus. Passing toward the portal fissure in the cap- 
sule of Glisson, they attain great size, and present a distinct mucous lining and a 
thick fibrous coat, in which are many circular and longitudinal bundles of smooth 
muscular tissue, irregularly disposed. One trunk from the left and one from the 
right unite in the portal fissure and form the hepatic duct, which runs two 
inches downward and to the right, and there joins the cystic (gall-bladder) duct, 
thus forming the common bile duct (ductus communis choledochus),.o, tube about 
three inches long, which passes downward and 
backward to the second part of the duodenum, 
where it pierces the muscular wall of that bowel, 
runs in the submucous space for a half-inch or 
more, and opens in conjunction with the pan- 
creatic duct into the lumen of the duodenum, 
about four inches below the pylorus. 
The Gall-bladder. 
The gall-bladder {vesica, felled) (Fig. 805), the 
reservoir of the bile, is a pear-shaped bag, nearly 
four indies long, an inch and a half wide, and with 
a capacity of rather more than an ounce. It lies in 
the wide fissure to which it gives its name, some- 
times projecting a little beyond the front margin 
of the liver, covered on its blunt (forward) end, 
its sides, and its under surface by serous mem- 
brane, which is stretched across from the right 
lobe to the quadrate. Its principal coat is com- 
posed of condensed areolar tissue, in which are 
irregularly disposed many bundles of unstriped 
muscle. The lining of mucous membrane has a 
honey-comb appearance. The tube of discharge. 
common\' 
BILE DUCT\ 
Fig. 805,—The cystic duct in section, 
with part of the gall-bladder, hepatic and 
common bile ducts. (Testut.) 
the cystic duct, about an inch long, has a structure like the other bile duets, but 
presents the peculiarity of a number of oblique folds of its mucous membrane, 
which project into the bore and suggest the thread of a screw. All through the 
large bile ducts and in the gall-bladder there are mucus-secreting glands. THE LIVER. 
747 
Size and Weight of the Liver.—The adult liver measures 10 or 12 inches from 
end to end, 6or 7 inches fore-and-aft, 3or 4 vertically in the thickest part. Its 
weight is from three to four pounds. Its weight relatively to that of the entire 
body varies enormously at different periods, being one-third when the embryo is 
two months old, and one thirty-sixth or less in middle life. It diminishes in size 
and weight as old age creeps on. It is brownish-red in color, often presenting a 
mottled appearance. It is firm to the touch, but rather friable; and, when torn 
across, the exposed surface is seen to be distinctly granular on account of the 
presence everywhere of the lobules. 
Situation of the Liver (Fig. 806).—The position of the liver in the right hypo- 
chondriac, epigastric, and left hypochondriac regions is not entirely unchangeable, 
but is modified by a number of circumstances, particularly by respiration, the 
CAVITY or 
PERICARDIUM 
DIAPH- 
RAGM “I 
TENTH \ 
RIB '“’l 
LOWER 
LIMIT OF I 
PLEURA I, 
I 
LOWER 
■LIMIT OF 
PLEURA 
DUODENUM 
Fig. 806.—Coronal section of trunk, showing relations of thoracic and abdominal viscera. Front surface 
of rear segment. (Testut.) 
attitude of the body, the distension or emptiness of stomach and colon, and the 
tightness of the clothing of the thorax. To these influences, which are not 
pathological, may be added various others, which result from disease. In forced 
inspiration the dome of the right lobe may be driven down to the level of the 
ninth thoracic vertebra; in forced expiration it may rise as high as the upper 
border of the eighth thoracic vertebra. If a knife were to be inserted horizon- 
tally into the thorax on the plane of the fourth costo-chondro-sternal junction, it 
would be likely to shave the summit of the hepatic dome. This gives one a good 
idea of the greatness of the encroachment of the abdomen upon the space which 
the lower margins of the thoracic cage suggest to the casual observer as belong- 
ing to the chest cavity. 
Relations of the Liver.—The liver is in relation above with the diaphragm, 
which separates it from the heart and lungs, the first of these organs making its 
position apparent by a shallow depression on the top of the left lobe, and the 
others, more yielding in their nature, indicating their location by the great bulges 
which they permit the liver to make into their under surfaces. Its upper surface 
is also in contact with the anterior wall of the abdomen above a line drawn from 
the eighth costal cartilage on the right to the middle of the seventh on the left; 
for the upper surface slopes markedly forward and downward, and justifies the 
name which is sometimes given it—the antero-superior surface. The Spigelian 
lobe lies against the right crus of the diaphragm, opposite the tenth and eleventh 
thoracic vertebrae. The relations of the other portions of the liver with contiguous 748 
THE ORGANS OF DIGESTION. 
viscera are so clearly indicated in the pictures that it is unnecessary to recapitu- 
late them. 
Partial Summary.—Some of the principal facts of gross, hepatic anatomy may 
be tabulated for mnemonic purposes as follows : 
Umbilical Fissure 
Gall-bladder Fissure 
Portal, or Transverse Fissure 
Ductus-venosus Fissure 
Vena-cava Fissure 
Five Fissures 
on under surface 
on hind surface. 
Left. 
Bight, subdivided into 
Quadrate 1 1 L. 
n , , >on under surface. 
Caudate j 
Spigelian on hind surface. 
Five Lobes 
Branches of Portal Vein. 
Branches of Hepatic Artery. 
Badicles of Hepatic Veins. 
Bile Ducts. 
Lymphatics. 
Five Sets 
of 
Vessels 
Suspensory, Broad, or Falciform. 
Coronary. 
Bight Lateral, or Bight Triangular. 
Left Lateral, or Left Triangular. 
Bound—obliterated Umbilical Vein. 
Five Ligaments 
_ . , 
* enloneal 
In the preceding descriptions of the abdominal digestive organs it has been 
necessary to make frequent reference to their serous coat. In every case this 
covering is a part of the 'peritoneum ; and, although one organ which is com- 
pletely invested, and several which are only partly clothed by it, are yet to be con- 
sidered, it seems best at this stage to present an account of this great mem- 
brane as a whole. 
THE PERITONEUM. 
It may be well for the student to refresh his memory by referring to what is 
said of serous membranes in general on page 66, and of the development of the 
intestines on page 88. 
The peritoneum is by far the most extensive and most complicated of the 
serous membranes. Its extreme complexity is due to changes in the position of 
the viscera in their development, and to obliterations which have taken place on 
account of the adhesion of certain apposed surfaces. It does not meet all of the 
requirements of a typical serous membrane, because in females it is not a shut 
sac, there being a continuity of its surface and that of the mucous membrane 
lining the oviduct, and, consequently, a communication between its cavity and 
the surface of the body. 
Between it and the parietal structures which it lines is a variable amount of 
areolar tissue called subperitoneal, sometimes containing fat-cells. This permits a 
degree of motion of the peritoneum upon subjacent parts. The connection 
between the serosa and its viscera is usually much closer. 
The viscera are connected to the abdominal parietes and to each other by folds 
of peritoneum. These have received various names, as mesenteries, omenta, and 
ligaments. 
A mesentery is a double fold of peritoneum, enclosing the vessels, nerves, etc., 
devoted to a portion of intestine. Specifically, and always when used alone, the 
name refers to the mesentery of the small intestine, described on page 718 ; but 
the term is often employed in a larger and generic sense to indicate a similarly 
Mesenteries. THE PERITONEUM. 
749 
constituted structure, attached to any organ. Thus, we may speak of the mesen- 
tery of the gall-bladder, seen in cases where this reservoir, instead of being held 
close to the liver, as is usually the fact, hangs away from it at some little distance, 
depending from a double, serous fold, which encloses its vessels and nerves. 
The mesenteries of portions of the large intestine are called by specific names, 
as transverse mesocolon, sigmoid mesocolon ; and exceptionally we find an ascending 
mesocolon, or a descending mesocolon. The mesentery of the vermiform appendix 
is called the mesenteriolum (“ the little mesentery”). 
The Mesentery proper extends from the left side of the second lumbar verte- 
bra obliquely downward to the right iliac fossa. The transverse mesocolon 
crosses the abdomen horizontally at the level of the third portion of the duodenum. 
The sigmoid mesocolon begins in the left iliac fossa, passes downward and to the 
right until it reaches the middle line of the sacrum, in which it then goes down- 
ward a short distance. The occasional ascending mesocolon lies behind the portion 
of intestine to which it belongs, and the same is true of the rare descending 
mesocolon. 
Fig. 807.—The great omentum as seen from the front. (Testut.) 
Omenta. 
Omentum (epiploon) is a terra applied to a fold of peritoneum connecting the 
stomach with some other viscus. 
The gastro-hepatic (“ stomach-liver ”) omentum or small omentum extends from 750 
THE PERITONEUM. 
the small curvature of the stomach and the adjacent first part of the duodenum to 
the portal fissure of the liver, and encloses the tubes which enter and leave this 
opening. 
The gastro-colic (“stomach-colon”) omentum or great omentum (Fig. 807) con- 
nects the great curvature of the stomach and the adjoining first part of the 
duodenum with the transverse colon. This omentum is far more voluminous 
than is necessary to establish a bond of union between the stomach and colon : it 
hangs downward in front of the mass of small intestines like an apron, and car- 
ries in the interstices of its structure an amount of adipose tissue, which varies 
according to the fatness of the individual. This protective organ, so serviceable 
in keeping the bowels warm, justifies the alleged origin of its name, which makes 
it mean “ coverlet.” 
The gastro-splenic (“ stomach-spleen ”) omentum is a double fold of peritoneum, 
passing from the dorsal surface of the stomach, near its left border, backward 
and inward to the anterior margin of the hilum of the spleen. It runs below into 
the gastro-colic omentum. It is often called the gastro-splenic ligament. 
Ligaments. 
Other folds of peritoneum, connecting two viscera, or a viscus with the 
abdominal wall, are called ligaments. 
The name hepato-duodenal ligament is sometimes applied to the right, free mar- 
gin of the gastro-hepatic omentum, which connects the liver and duodenum. 
The ligaments of the liver, which are formed from peritoneum—suspensory, 
coronary, lateral—have already been discussed. 
The lieno-renal (“ spleen-kidney ”) ligament, including the lieno-pancreatic 
ligament, which is its ventral layer, will be described in connection with the 
spleen. The peritoneal ligaments of the bladder and the uterus will be more 
fittingly treated of in the chapters on the urinary and the reproductive organs. 
The phreno-eolie (“ diaphragm-colon ”) ligament, also called costo-colic, is a 
small fold stretching from the diaphragm near the tenth or eleventh rib of the 
left side to the colon near the spleen, and giving mechanical •support to the last- 
named organ. 
The peritoneum as a whole is to be regarded as a bag, constricted to a mere 
passage-way at one point, so that there are formed two cavities, a great one and a 
small one, communicating through a narrow throat. 
General View of the Peritoneum. 
\ gall\ , 
\B LADDER 
VENA CAVA INFERIOR 
HEPATO-REN/ffl 
LIG 
/ ■/ nmMt.issss 
mmmm 
DUODENUM 
Fig. 808.—Dissection to show relations of the foramen of Winslow, to which the dart points. The front of 
the right portion of the gastro-hepatic omentum has been cut and turned off to the left, and the liver lifted up 
and back, displaying the objects in the front wall of the foramen. The horizontal broken line marks the posi- 
tion of the section from which the next picture was made. (Testut.) 
The small sac of the peritoneum lies behind the large sac, and furnishes the 
serous surface for the back of the stomach, the Spigelian lobe of the liver, and the THE PERITONEUM. 
751 
front of the pancreas. The other abdominal viscera have their serosa from the 
great sac. 
The narrow strait between the great and small cavities of the peritoneum is 
called the foramen of Winslow, and foramen epiploicum (Figs. 808, 809). It is 
bounded in front by the vessels entering and leaving the portal fissure of the liver, 
VERTEBRA 
SUPRARENAL CAPSULE 
GREAT CAVITY OF 
PERITONEUM 
COMMON 
BILE DUCT 
HEPATIC 
ARTERY 
Fig. 809.—Transverse horizontal section through the foramen of Winslow. The lower end of the Spigelian 
lobe has been shaved off, and the upper surface of the piece is seen. (Testut.) 
behind by the vena cava inferior, above by the caudate lobe of the liver, and 
below by the duodenum. It is large enough to admit two fingers. 
The Small Sac of the Peritoneum (Figs. 810, 811).—In the embryo the small 
sac reaches at first but little lower than the stomach ; but afterward it enlarges 
rapidly by extension downward, and forms a pouch, which hangs from the great 
curvature of the stomach in front of the intestines, and contracts adhesion to and 
blends with the front part of the serous coat of the transverse colon, thus estab- 
LIVER 
LIVER 
NUM 
.DUODE- 
NUM 
TRANSVERSE 
“ COLON 
TRANSVERSE 
COLON 
SMALL 
—’INTESTINE 
SMALL 
INTESTINE 
Fig. 810.—Diagram of a sagittal section of the 
abdomen of an embryo, showing the reflections of 
the peritoneum in the great cavity and the small 
cavity. (Testut.) 
Fig. 811.—Diagram of a sagittal section of the abdo- 
men of an adult, showing the growth of the small 
cavity, and the application of its rear wall to the trans- 
verse colon and mesocolon. Compare with preceding 
figure. (Testut.) 
lishing a connection between the stomach and colon, which is called the gastro- 
colic omentum, on account of the organs which it unites, and great omentum, because 
it is so much larger than the gastro-hepatic. It is thus seen that the name “ cavity 
of the great omentum ” is synonymous with “ the small cavity of the peritoneum.” 
Not only does the small sac become adherent to the colon, but its posterior 
double layer becomes attached to and merged with the anterior (upper) surface of 
the transverse mesocolon,; and so intimate is this connection that this part of the 752 
THE PERITONEUM. 
colon seems to be entirely surrounded by the rear wall of the sac. Furthermore, 
adhesion takes place between the layers of the pouch which are below the level 
of the transverse colon, absorption occurs at many points, and the four-layered 
apron is converted into a coarse lace-work, in whose meshes a considerable deposit 
of fat appears. 
It is useful to trace the course of the peritoneum at different planes in order 
to obtain a comprehension of its continuity, the relations which it sustains to the 
abdominal viscera, and the relations which it maintains between them. 
If we make a horizontal section of the abdomen a little above the iliac crests, 
and inspect the upper surface of the lower segment, we shall obtain such a view 
as is presented in the semidiagram, Fig. 812. Beginning at the descending colon, 
Mesentery Aorta 
Small 
intestine 
Lymphatic 
node 
Vena cava 
inferior 
Ascending 
colon 
Peritoneum 
Mesocolon 
! (imperfect) 
y' Psoas 
Descending* 
colon 
Right 
kidney 
Left kidney 
Fig. 812.—Course of the peritoneum, as seen in a horizontal section above the iliac crests. Semidiagram- 
xnatic. (Tillaux.) 
we trace the peritoneum over its left side, front, and part of its right side, but 
not upon its back, for it has no mesentery ; thence it extends to the face of the 
left kidney, which, like its mate, lies entirely behind the serosa, in other words 
is retroperitoneal; from this organ the peritoneum stretches over the psoas mag- 
nus and onto the vertebral column and the aorta, which rests on its ventral sur- 
face ; then it passes forward as the left side of the mesentery, covering the vessels, 
nerves, nodes, and fat which are the essential parts of that structure, envelops 
the small intestine, and returns to the vertebral region as the right side of the 
mesentery; here it partially coats the inferior vena cava, runs onto the right 
psoas, touches the right kidney, and turns around the ascending colon, giving it 
a larger covering than it favored the descending colon with, though it leaves its 
dorsal part nearly or quite bare ; thence it again reaches the right kidney, whose 
anterior aspect it partially clothes, and from this is reflected to the abdominal 
wall, and sweeps around to the starting point in a great expanse of parietal peri- 
toneum . 
If we examine the surface of this anterior wall at a lower level, we shall 
observe a median ridge from the bladder to the umbilicus, due to the urachus; on 
each side of this a ridge, sloping down and outward from the navel, these being 
caused by the obliterated hypogastric arteries ; nearly parallel with these and 
further to the side, are slight elevations, which are produced by the epigastric 
vessels; and, running down and inward from the iliac spines, the inguinal liga- THE PERITONEUM. 
753 
merits. In the angle between the epigastric vessels and the inguinal ligament is 
a slight depression, the external inguinal fossa, marking the internal abdominal 
ring, the beginning of the inguinal canal; in the angle between the hypogastric 
ridge and the inguinal ligament is the middle inguinal fossa ; below this, toward 
the side and beneath the inguinal ligament, is the femoral fossa ; and between the 
urachus and the hypogastric artery is the internal inguinal fossa. 
If we trace the peritoneum vertically, beginning on the superior surface of 
the liver, we pass down to its anterior border, back and upward on its inferior 
surface to the portal fissure, where we come in contact with the small omentum, 
which guides us downward to the front of the stomach, passing over which we 
reach the anterior surface of the great omentum, and this, being followed over its 
lower edge and posterior aspect, leads to the transverse colon ; thence beneath the 
transverse mesocolon the course lies upward and backward to the third part of the 
duodenum, where an abrupt change of direction occurs, and the membrane is traced 
downward over the mesentery and jejuno-ileum, and back on the other side of the 
mesentery to the hind wall of the abdomen, which is again left to form the serous 
part of the sigmoid mesocolon and the outer tunic of the sigmoid colon. After 
this the course is different in the two sexes. In the male the peritoneum goes from 
the rectum to the bladder a short distance above the prostate gland, forming the 
recto-vesical pouch, covers the superior surface, and thence extends to the front 
abdominal wall. In the female it passes from the rectum to the upper extremity 
of the vagina and the uterus, forming the recto-vaginal or recto-uterine pouch, called 
also the cul-de-sac of Douglas ; then covers the supravaginal part of the uterus, from 
which it extends to the bladder, and then to the anterior wall of the abdomen. 
Its course upward requires no especial mention, other than that already given it, 
until the navel is reached. Above this there runs upward and slightly to the 
right a ridge which ends above at the anterior border of the liver, and encloses 
the round ligament of the liver. At the sides of this elevation the peritoneum is 
traced smoothly over the anterior belly-wall and onto the under surface of the 
diaphragm, from which it turns to the upper surface of the liver, where the 
excursion was begun. 
Variations from these two simple tracings occur, as the planes of the sections 
are made in different directions; but these examples give a correct idea of the 
chief features of the peritoneal complications. 
Retroperitoneal Fossae. 
At certain places the peritoneum is marked by the presence of one or more 
crescentic folds, bordering the openings of distinct pouches or fossae, which are 
of practical interest as being the sites of retroperitoneal herniae. They occur in 
the regions of the duodenum, the sigmoid colon, and the caecum. 
About the duodenum, three of these pits are recognized. The most common 
is the inferior duodenal fossa, situated in the lower and external portion of the 
fourth part of this intestine, its mouth directed upward. The superior duodenal 
fossa, also in connection with this part, opens downward, its orifice facing that of 
the superior fossa. Both of the preceding are frequent. The duodeno-jejunal 
fossa is rare. It begins on the back of the jejunum, and extends upward to the 
duodeno-jejunal junction. 
The intersigmoid fossa begins in the left iliac fossa at the proximal part of the 
sigmoid mesocolon, and runs upward behind the peritoneum of the dorsal abdomi- 
nal wall. 
In the csecal region a number of fossae may be found, of which the most 
important is the postccecal fossa, which extends upward behind caecum and 
ascending colon for a variable distance. It may include the proximal part of 
the appendix vermiformis, and cause annoyance in operations upon this organ. THE ORGANS OF RESPIRATION 
F. H. GERRISH. 
PHYSIOLOGICAL ANATOMY. 
RESPIRATION is a dual function, consisting of the simultaneous expulsion 
of certain waste matters and appropriation of a nourishing material. The 
substance which is introduced in this process is gaseous, and the things which 
are eliminated are either gaseous or vaporized. The double performance is popu- 
larly called breathing. 
The apparatus necessary for respiration consists of a thin, moist membrane, 
exposed on one side to air, and on the other to a moving stream of blood (Fig. 
813). Each of these fluids gains something from, and loses something to, the 
THIN MUCOSA 
A I R 
CAPILLARY BLOOD VESSEL 
Fig. 813.—Diagram of the essentials of a respiratory apparatus. (F. H. G.) 
other : the air parts with oxygen and takes on a load of effete materials ; while, 
at the same time, the blood gives up certain waste products and appropriates the 
oxygen—the most important item of the body’s income—these various substances 
passing readily through the delicate membrane, which is mucous. 
In different classes of animals the necessary structural conditions are afforded 
in various ways. In some aquatic creatures the respiratory membrane is spread 
over the surface of a plume-like organ that projects from the body and waves 
about in the water, which always contains air (Fig. 814). A more common device 
is that of gills, in which the mucous mem- 
brane is disposed in layers, between which 
the air-laden water is drawn, being taken in 
at the mouth and ejected at the sides of 
the head. In the tadpole, which lives en- 
tirely in the water, the breathing organs are 
gills; but the frog, into which the tadpole 
develops, has a very different apparatus. 
Gradually the structural peculiarities of the 
aquatic animal are lost, and those of the 
amphibian are acquired; and, synchron- 
ously with the shrinkage of the fish-like tail, 
and the growth of the limbs, is observed 
Fig. 814.—Head and gills of Menobranclius. 
(Dalton.) 
the development of a new breathing-apparatus, unfit for abstracting oxygen from 
the air which is contained in water, but capable of taking the gas directly from 
the ordinary atmosphere. It is a sac, wholly contained in the trunk, and into it, 
at brief intervals, a quantity of air is drawn, permitted to remain a short time, 
and then expelled by the channel of entrance. This sac is lined with a delicate 
755 756 
THE ORGANS OF RESPIRATION 
mucosa, with the attached surface of which a network of capillaries is in contact. 
It is a very simple kind of lung, and yet is the type on which the most complex 
respiratory organ is constructed. 
An animal which requires, on account of the rapidity of his tissue-changes, a 
very large supply of oxygen, would find locomotion impracticable, if his respira- 
tory membrane was at the surface, projecting like a tree, or arranged like gills ; 
but it is manifest that there is not sufficient room in the entire body for a simple 
sac, whose lining would afford a surface large enough to meet the requirements 
of the case. The problem presented is that of providing a great extent of sur- 
face within a limited cubic space. It is the same question as that which confronts 
the librarian, whose books are vastly too numerous to be accommodated by the 
entire available area of the walls of the room. He neither appropriates more 
apartments, nor builds an addition to the house; 
but he constructs partial partitions, projecting 
from the walls toward the centre of the room, 
making alcoves of the intervening spaces, and 
thus enormously multiplies the shelving capacity. 
Nature adopts this plan in the lung, and, by form- 
ing alcoves at the periphery of the original sac, 
augments its available surface without increasing 
its cubic capacity. The lung of the frog illus- 
trates this fact; a sectional view (Fig. 815) shows 
Fig. 815.—Lung of frog, cut open, 
showing its internal surface. (Dalton.) 
that the mucosa is folded into partial partitions, between which are little recesses 
around the periphery, all opening into a clear, central passage. 
The complex lung of man is built upon this type. But the complexity of the 
human lung arises not largely from elaboration of the plan, but from immense 
multiplication of the structure. The great size of the human being and his rela- 
tively greater activity require not a different kind of lung, but a host of lungs 
of the same kind. Therefore, the human lung may well be regarded as a vast 
community of batrachian lungs, with the addition of such accessories as the 
immensity of the collection makes necessary. 
The alcoves—to repeat the library simile—are called air-vesicles, alveoli, or air- 
cells—the last name being objectionable on account of the different use of the 
word “ cell ”in histology. A collection of alveoli around a central hall consti- 
tutes an infundibulum, so called from its funnel-shape. A group of closely 
related infundibula makes a lobule. A great community of lobules is a lobe. 
Two or three lobes make a lung. 
In mode of development and general appearance a lobule bears a striking 
resemblance to a racemose gland. The stem of a lobule is an air-duct, and from 
this, within the lobule, branch the more minute tubes, which serve as stems for 
the infundibula, three of the latter often being connected with one of the former. 
The duct of the lobule unites with another of like size, making a larger one; 
this last joins with its equal, and so on progressively until tubes of considerable 
size are reached, Avhich either pursue this method, or enter the sides of those 
which are larger. Finally, for each of the two lungs a single tube results, and 
the two combining form a great median pipe. Beyond this the air-channels do 
not have the regularity of shape which has characterized the system up to this 
point. They are the larynx, the pharynx, and the passages of the nose. 
x 7 L - 7 JO 
Tracing the air-ducts in reversed order from the surface of the body to the 
depths of the lung, we have— 
1. The nasal passages. 
2. The upper and middle portions of the pharynx. 
3. The larynx. 
4. The trachea (the windpipe). 
5. The two bronchi—one bronchus for each lung. 
6. The bronchia (bronchial tubes, bronchioles) of all sizes from the largest to 
the smallest. 757 
THE TRACHEA. 
The nasal passages, as cavities in the skull, are treated of in the chapter on 
osteology, as olfactory structures, in the chapter on the organs of the special 
senses. The pharynx, being an alimentary as well as a respiratory organ, has 
already been presented as a part of the digestive tract. -The larynx, which is the 
organ of voice, is the highly specialized upward continuation of the trachea, and 
its description would best be deferred until the simpler structures have been con- 
sidered. 
We now have before us an outline of the physiological anatomy of the breath- 
ing apparatus, and are prepared to study the structures in detail. This can 
most profitably be done by beginning with the windpipe and proceeding in an 
unbroken course to the air-vesicles. 
THE TRACHEA. 
The trachea (so called from the Greek word for “ rough/’ on account of the 
marked inequalities felt on its surface), or windpipe (Fig. 816), is a straight tube, 
situated in the middle line of the lower and 
front part of the neck and the upper part 
of the thorax, in front of the oesophagus, 
extending from the lower border of the 
larynx downward and backward to its di- 
vision in the bronchi, and from the plane 
of the sixth cervical to that of the fourth 
thoracic vertebra. When the face is di- 
rected forward, the trachea is a little more 
than four inches in length ; but this meas- 
urement may be increased by the forcible 
extension of the neck and diminished by 
sharp flexion, the variation between the 
shortest and longest measurements exceed- 
ing one and a half inch. Its average 
transverse diameter in the cadaver is four- 
fifths of an inch, the antero-posterior a 
trifle less; but both are smaller during 
life on account of the activity of the mus- 
cular part of the pipe. It is convex and 
rigid in front and at the sides, flat and flex- 
ible behind. 
The framework of the trachea consists 
of mixed white and yellow fibrous tissue, 
and strips of pure cartilage, the latter being 
embedded in the front and sides of the 
tube made by the former. The pieces of 
cartilage are very irregular in shape—some 
beina- of nearlv uniform width from one 
THYROID 
IMPRESSION 
AORTIC 
IMPRESSION 
Fig. 816.—Trachea and bronchi, front view. 
(Testut.) 
end to the other, some bifurcating at one 
end, some having a branch near the middle; but their general direction is hori- 
zontal, and, seen from the front or side, they produce the effect of nearly parallel 
bands. But they are not rings, though often so called ; for they do not encircle 
the trachea, but always end at the border of its flat, hind surface. They vary in 
number from fifteen to twenty. The highest one is wide and firmly attached to 
the lowest cartilage of the larynx; the lowest sends a spur downward and back- 
ward from its centre, between the origins of the bronchi. The fibrous mass in 
which the cartilages are embedded is caused by them to bulge in transverse lines, 
thus being produced the irregularities which give the trachea its name. Ossifica- 
tion of the cartilages begins at forty or fifty years of age. 
The flat, hind wall, instead of being stiffened with cartilage, is made contrac- 758 
THE ORGANS OF RESPIRATION. 
tile by a continuous sheet of unstriped muscle which it encloses. The bundles of 
muscular fibres run horizontally, and are attached to the ends of the cartilages 
where these exist, and to the fibrous wall in the interspaces. In front of the 
muscle are conspicuous longitudinal bundles of yellow fibrous tissue. 
The cartilages serve the purpose of preventing the collapse of the trachea from 
external pressure or from sudden internal suction. The necessities of human 
respiration require permanence of the lumen of the pipe, a condition which would 
not be satisfied by a less rigid material than cartilage. The elasticity of the yel- 
low fibrous tissue permits the considerable elongation which movements of the 
head demand, and ensures perfect restoration and even some shortening beyond 
the average length. The white fibrous tissue gives strength, flexibility, and 
toughness. The muscular tissue in the flat, hind portion causes approximation 
of the ends of the cartilages under nervous stimulus, and diminution of the 
calibre of the tube. 
The lining of the trachea is smooth mucous membrane, the epithelium of which 
is columnar, stratified, and ciliated. The deepest layer of the corium is com- 
posed almost wholly of yellow fibrous tissue. The submucous, areolar coat, con- 
necting the mucosa with the fibrous tunic (in which, as has been already said, are 
the cartilaginous and muscular elements), contains many racemose mucous glands, 
the ducts of which discharge into the tube. The greater part of these glands are 
in the spaces between the cartilages and in the hind wall. 
The principal arteries of the trachea are the inferior thyroid, its lymphatics are 
tributaries of the bronchial and deep cervical nodes, and its nerve-supply is derived 
from the pneumogastric and great sympathetic. 
The trachea lies in the midst of an abundant mass of areolar tissue, which is 
so loose as to permit free movement up, down, and horizontally. 
The lower end of the trachea bifurcates laterally into the bronchi (Fig. 817), 
which strangely get their name from the Greek word for “ throat.” They pass to 
the right and left lungs respectively. In structure and general form they are 
exact continuations of the trachea, with convex front and sides, which are 
stiffened with cartilaginous bands embedded in fibrous tissues, a flat back, which 
is fibrous and muscular, and a lining of mucous membrane, whose epithelium is 
cylindrical, ciliated, and in layers. The right bronchus is the shorter (a scant 
inch), wider (f inch), and more nearly horizontal; the left bronchus is the longer 
(about two inches), narrower (|- inch), and more nearly vertical. They are sup- 
plied by the bronchial arteries, and by nerves from the pulmonary plexus. 
THE BRONCHI. 
THE BRONCHIA. 
The air-ducts, leading from a bronchus into the depths of the lung, are called 
bronchia, bronchial tubes, or bronchioles (Fig. 817). The right bronchus gives 
three branches to its lung, the left only two. The tubes divide progressively, 
(sometimes dichotomously, sometimes otherwise), into smaller tubes down to the 
infundibula, the ducts of which are about inch in diameter. Although the 
bronchioles are continuous with the bronchi, as the latter are with the trachea, 
they have a different shape—the bronchi and windpipe being flat behind, all the 
other tubes perfectly cylindrical. In other words, the outline of a transverse 
section of every pipe concealed within the lung is circular, while that of those 
which are outside of the lung is convex only in front and at the sides. 
The bronchioles have three coats—mucous, muscular, and fibrous. The 
mucous membrane is everywhere provided with ciliated epithelium, the lashes of 
which beat always toward the larger tubes, thus preventing an accumulation of 
mucus in the air-vesicles. Glands are numerous, except in the very small tubes. 
The muscle fibres of the middle coat are transversely arranged, and are relatively MINUTE ANATOMY OF THE LUNGS. 
most conspicuous in the smallest tubes. The fibrous coat contains not only white 
fibrous tissue, but also many yellow fibres. It diminishes in thickness as the 
tubes become smaller, and is extremely thin within the lobules. In the tubes 
which have a diameter of inch or more this coat is strengthened by cartilagin- 
Fig. 817.—Bronchi and bronchioles. The lungs have been widely separated, and tissue cut away to expose 
the air-tubes. (Testut.) 
ous plates, not disposed in an annular way, as in the trachea and bronchi, but 
irregularly scattered through the tunic. 
The tubes which have no cartilages are also deficient in glands; but their 
lining membrane is kept moist by a smear of mucus furnished by goblet cells. 
The muscular tunic in these minute tubes, although scanty, is important, as it 
possesses the power of narrowing their calibre, and thus diminishing the size of 
the air-current. In asthma the exaggeration of the normal action of this coat is 
responsible for the difficulty in breathing. 
MINUTE ANATOMY OF THE LUNGS. 
Upon the walls of the minute bronchioles little bulges appear, at first rarely, 
but with increasing frequency as the distal end of the tube is approached. 
Finally the bronchiura widens out and terminates in an irregular chamber, the 
sides and blind end of which are closely set with these little protrusions, and we 
have the ultimate and essential part of the respiratory apparatus—an infundi- 
bulum. The minute blebs on the tubes seem to be the result of an effort of 
nature to form an infundibulum before all of the necessary conditions are favor- 
able. Again and again the attempt is made, always with greater results, and at 
last the whole remainder of the tube undergoes the transformation. The pouches 
are the alveoli (air-sacs, air-vesicles, air-cells). The infundibula are not always 
funnel-shaped, as the name implies, but are often very irregular in form. 
Structure of an Infundibulum (Fig. 818).—The framework of an infundibulum 760 
THE ORGANS OF RESPIRATION. 
is very thin, transparent, and composed of fibrous tissue, the yellow variety being 
conspicuous, and forming a delicate network. A few smooth muscular fibres are 
Fig. 818.—Diagram of a lobule of the lung. A bronchiole is seen dividing into two branches, one of which 
runs upward and ends in the lobule. In the lobule are four groups of infundibula. At the left are two infun- 
dibula the alveoli of which present their outer surfaces. Next are three infundibula in vertical section, the 
alveoli of each opening into the common passageway. Upon the ultimate bronchiole of this group are alveoli. 
In the next group the first infundibulum shows a pulmonary arteriole surrounding the opening of each alveo- 
lus, and the second gives the same with the addition of the close capillary network in the wall of each alveolus. 
The same arrangement of vessels is seen in the alveolus upon the bronchiole of this group. Around the 
fourth group is a deep deposit of pigment, such as occurs in old age, and in the lungs of those who inhale coal- 
dust and the like. On the bronchiole lies a branch of the pulmonary artery (blue), bringing blood to the 
infundibula for aeration. It also supplies nourishing blood to the tubes and other structures within the 
lobule. Beginning between the infundibula are the radicles of the pulmonary vein (red), a root of which lies 
upon the bronchiole. The bronchial artery is shown as a small vessel bringing nutrient blood to the bronchiole 
(outside of the lobule), the artery and vein, and all of the structures between and around the lobule. No attempt is 
made to show the sustentacular tissue which occupies the spaces within and around the lobule. (F. H. G.) 
found between the air-vesicles. Next to this wall is a dense network of capil- 
laries, the spaces between which are not as wide as the vessels themselves. 
The lining of an infundibulum and its air-vesicles is a delicate epithelium, 
which is directly continuous with that of the mucosa of the tubes. It is chiefly MINUTE ANATOMY OF THE LUNGS. 
761 
composed of broad, flattened, non-ciliated cells of extreme thinness, among which 
are scattered here and there little clusters of small polygonal cells, like those 
which in the foetus form the entire epithelium of this part. The iirst full expan- 
sion of the vesicle by the inrush of air after birth stretches out almost all of the 
cells, but leaves in their embryonic condition the few which, if enlarged like the 
majority, would make the lining too voluminous. The cells are so thin that the 
blood in the capillaries is separated from the air by so small an amount of tissue 
that the least possible resistance to the passage of gases back and forth is inter- 
posed. At points where the edges of several cells converge are often seen minute 
stomata, opening into lymph-channels of the areolar tissue. 
The free edges of the air-vesicles support a fine arteriole, which twists in and 
out, now on this and then on that side of the dividing line between two adjacent 
alveoli, and from this tortuous encircling vessel the capillary network is given off 
to the neighboring vesicles. Those portions of this plexus which are on walls 
between alveoli have two surfaces exposed to air, one in one vesicle and one in 
another. 
-LEFT AURICU 
APPENDIX 
—LEFT 
VENTRICLE 
RIGHT E 
VENTRICLES 
BRONCHIAL 
TUBES 
RIGHT 
AURICLE 
Fig. 819.—The pulmonary artery. The front part of the right lung has been removed, and the pulmonary 
vessels and the bronchial tubes are thus exposed. (Testut.) 
Two or three infundibula may start from the end of one bronchiole. The 
infundibula are gathered into groups of approximately uniform size, which, with 
the necessary vessels, nerves, and uniting areolar tissue, constitute lobules. Ihe 
lobules at the periphery of a lung are more or less pyramidal ; but the others are 
packed together so closely that they have become reciprocally compressed into 
various and fantastic forms. 
Between the lobules is areolar tissue, which is abundant in the infant, scanty 
in the adult; consequently their isolation is easy in the former, and difficult or 
even impossible in the latter case. This interlobular areolar tissue and also that 
between the alveoli after early life is the seat of a deposit of carbonaceous matter, 
doubtless inhaled, and carried by lymph-channels to this tissue and to lymph- 762 
THE ORGANS OF RESPIRATION. 
nodes. This deposition of pigment makes clear the outlines of the lobules and 
even of the bases of the infundibula. 
Blood-vessels of the Lungs.—Two sets of blood-vessels are distributed to the 
Jung and to all of its lobules—the branches of the pulmonary artery and those of 
the bronchial arteries. The latter furnish nourishing blood to the organ; the 
former carry to it venous blood, which is to be aerated, that is to say, to be re- 
lieved of certain materials which are the result of tissue-waste, and to be loaded 
up from the air with oxygen—the most important of the articles of physiological 
income. 
The pulmonary artery (Fig. 819), by its branches, accompanies the tubes and 
carries the greatest part of its blood to the capillary plexus of the alveoli; but 
some of it is supplied to the mucous membrane of those bronchioles which are 
near the infundibula—those which have air-vesicles upon them. The pulmonary 
veins (Fig. 820) begin by radicles at the margin of the capillary network of the 
ENTRANCE OF 
VENA AZYGOS 
BRANCH OF PU L- 
MONARY ARTERY 
VENTRICLE 
LEFT 
AURICLE 
Fig. 820.—Pulmonary veins, seen in a dorsal view of the heart and lungs. (Testut.) 
alveoli and the minute tubes—that is, they take blood from the parts to which 
the pulmonary artery is distributed. 
The bronchial arteries follow the divisions of the air-tubes, and supply arterial 
blood to the walls of the tubes (except the smallest), the coats of the large ves- 
sels, to which they are vasa vasorum, the bronchial lymph-nodes, the pleura, the 
areolar tissue beneath the pleura, and that between the lobules. The bronchial 
veins gather the blood from all of the parts to which the bronchial artery supplies 
it, excepting a little, which on account of a communication of the networks on 
the intralobular tubes and those which form the stems of the lobules, mingles 
with the blood furnished by the pulmonary artery, and is, consequently, taken 
up by the radicles of the pulmonary vein. 
GROSS ANATOMY OF THE LUNGS. 
The lungs (Figs. 821-823) (Latin pulmones, from which comes “pulmonary”) 
are two large organs, which occupy a great part of the chest cavity, one in each 
side of it, and separated from each other by the heart, the gullet, the great blood- GROSS ANATOMY OF THE LUNGS. 
763 
vessels, and other structures in the mediastinal space. Each lung presents an 
outer surface, which is convex, and adapted to the inner surface of the chest-wall 
of one side ; an internal or mesial surface, which is irregularly concave and occu- 
pied by mediastinal organs; an under surface or base, very concave and fitting to 
the upper surface of the diaphragm ; a summit or apex, which rises an inch above 
the level of the first rib; a hind border, rounded, vertical, and adjusted to the 
fev OBLIQUE 
l||k FISSURE 
IMPRESSIONS. 
OF RIBS 
-UPPER LOBE 
UPPER- 
LOBE 
JUNCTION OF] 
OBLIQUE AND I 
HORIZONTAL \l 
FISSURE JI 
LOWER 
LOBE 
MIDDLE LOBE 
LOWER LOBE 
Fig. 821.—Right lung, outer surface. (Testut.) 
Fig. 822.—Left lung, outer surface. (Testut.) 
long hollow made by the bodies of the thoracic vertebrae and the proximal portion 
of corresponding ribs; a front border, thin, irregular, and sloping from above 
downward and outward to the level of the fifth or sixth rib ; and a lower border, 
bevelled sharply at the expense of the lower surface, and marking the under limit 
of the outer surface. 
On the inner surface, three quarters way back from the front line, and about 
Fig. 823.—Lungs, dorsal view. (Testut.) 
equally distant from apex and base, is a vertical notch, the hilum, two inches long 
and an inch or more broad, which gives passage to the air-ducts, pulmonary artery 
and veins, bronchial artery and veins, lymph-vessels, and nerves, and affords 
lodgment to a considerable number of lymph-nodes. These different organs in 
the hilum are united into one large fagot, called the root of the lung. 
The inner surface of the left lung is much more deeply concaved than that of 
the right, on account of the greater encroachment of the heart upon the space at 764 
THE ORGANS OF RESPIRATION. 
the left of the middle line. The front border, also, for the same reason, is deeply 
notched. 
The right lung is on a somewhat higher plane than the left, on account of the 
greater elevation of the right half of the diaphragm, upon which muscle the 
lungs rest. 
Each lung is marked by a deep fissure (Fig. 824), which starts on the hind 
surface about three inches below the apex, and runs spirally around, terminating 
near the junction of the inner and lower borders. This fissure is very deep, 
extending inward nearly to the hilum, and dividing the lung into an upper lobe 
and a lower lobe. About half way of this oblique fissure on the right lung a second 
fissure (Fig. 825) begins and runs nearly horizontally toward the middle line, 
FiG. 824.—Position of the oblique Assure of the 
left lung with reference to the ribs. The humerus 
is raised. The line a* is the axillary line. (Testut.) 
Pig. 825.—Position of the Assures of the right 
lung with reference to the ribs. The humerus is 
raised. The line xx is the axillary line. (Testut.) 
ending at the anterior border. This fissure divides the upper lobe of the right 
side into two, which are called the middle lobe and the upper lobe. 
The left lung is taller, narrower, and more deeply excavated on its median 
surface ; the right is shorter, wider, less indented, and weighs a fifth more than 
the left. 
The volume of the lungs varies with the amount of contained air. In a new- 
born child, who has not breathed, the lungs occupy but a small part of the chest, 
seeming to be crowded upward and backward by the diaphragm, which stands at 
the level of the third rib. But they quickly expand when respiration is estab- 
lished, and thenceforth occupy all of the chest, except the central portion, as 
before stated. As, however, the capacity of the thorax is constantly fluctuating, 
owing to the respiratory movements, the lungs, which accompany the chest-walls 
in all of their advances and retreats, experience coincident and corresponding 
variations. 
The average capacity of the lungs is estimated to be nearly seven and a half 
pints. The entire respiratory surface at a moderate calculation is more than 870 
square feet, and some estimates place it very much higher. 
On account of the contained air the lungs are very light, and float readily in 
water. Fatal pulmonary tissue, however, never having contained air, is not 
very unlike liver in its specific gravity, as well as in its appearance, and sinks in THE PLEUREE. 
765 
water; and the presence or absence of the capacity of floating is a ready test of 
the establishment of breathing, where infanticide is suspected. _ 
The lunq substance or parenchyma is soft and spongy, and gives a crackling 
sound and a corresponding tactile sensation, when it is pressed between tic ngei 
and thumb, probably due to the crushing of the walls of the air-vesicles. The 
cohesive power of the lung is great, and it resists a high degree of pressure with- 
out rupturing. On account of the great figure played by the elastic tissue m the 
structure of the pulmonary substance, the lungs return readily to their former size 
immediately on the removal of the force which has caused their expansion. ic 
yellow fibrous tissue is always on the stretch in the normal condition, but never 
has an opportunity to assert its full power, even after death, unless the chest- 
cavity is opened. At a post-mortem examination the removal of the sternum and 
costal cartilages is instantly followed by the sudden collapse of the lungs, w nc i 
are reduced to one-third (or less) of their normal bulk the explanation being 
simply this : during life the air-pressure on the inside of the lung is sufficient to 
prevent the full action of the elastic tissue ; but, air being let in on the outer sur- 
face of the lung, the atmospheric pressure inside exactly balances that outside 
and the elasticity of the pulmonary substance, being unresisted, displays its lull 
The color of the lung differs widely according to age. Before respiration is 
established, it is a deep reddish-brown ; on inflation it changes to a beautiful rose- 
pink ; in early adult life it is grayish-white ; in early middle life it becomes brown- 
ish in spots and streaks ; and in old age it is often bluish-black. The alteration 
from the antenatal hue to the postnatal is manifestly due to the distention of the 
Inner with air—the color is diluted by distribution over a multiplied surface ; but 
the%)ther changes are largely caused by the deposition, in the areolar tissue 
between the infundibula and between the lobules, of carbonaceous particles, which 
have been taken up by the lymphatics. In the lungs of people who breathe air 
highly contaminated with such materials the changes occur much earlier in life, 
and are much more pronounced. This deposit makes a great deal clearer the out- 
lines of the lobules, and upon the free lung-surface their bases may be observed, 
occupying irregular polygonal areas from one-quarter of an inch and upward in 
diameterf Within these may be seen the outlines of the air-vesicles, measuring 
FlLifemC Ibundant in the areolar septa and in the bronchial mucous 
membrane, and are said to have been traced upon the walls of the alveoli, ihey 
drain these parts into the nodes in the root of the lung. 
The nerve-terminations are not known. The nerve-supply is from the pneumo- 
gastric and the sympathetic. 
THE PLEUEJE. 
Each lung is invested with a serous membrane, the pleura (from the Greek 
word for “side”) (Fig. 826). It is a perfectly typical shut-sac, one portion of 
which closely envelops the lung, entering its fissures and clothing their walls to 
the very bottom, and is called the visceral layer, or the pulmonary pleura and 
the other portion lines the walls of the great space in which the lung is contained, 
and is called the parietal layer. Different portions of the parietal layer are dis 
tinguished bv special names, which indicate their position. That which lines the 
ribs, costal cartilages, and intermediate muscles is the costal pleura; that which 
is attached to the diaphragm is the diaphragmatic pleura; that which is applied 
to the adjacent structures in the mediastinum is the mediastinal pleura - and that 
rising into the root of the neck and covering the dome of the lung is the cervical 
pf< As’a general rule the pulmonary or visceral pleura is in contact with some 
part of the parietal pleura; but in the fissures of the lung two layers of visceral 
pleura are in contact, and below the sharp, inferior border of the lung the two 766 
THE ORGANS OF RESPIRATION 
layers of the parietal pleura come together; for, although the lung everywhere 
else fills the space delimited by the pleura, it does not, even in the fullest inspira- 
Fig. 826.—Relations of lungs (red) and pleurae (blue) to the front walls of chest. (Testut.) 
tion, reach completely to the depths of this extra space (Fig. 827). We speak of 
a pleural cavity, but this is merely a term of convenience, and is not descriptive 
CAVITY OF 
PERICARDIUM 
vwm(avßsssKssshfis«se 
DIAPH- 
RAGM 
TENTH \j 
RIB | 
LOWER | 
LIMIT OF ! 
PLEURA / 
J 
7 LOWER 
'LIMIT OF 
PLEURA 
DUODENUM 
Fig. 827.—Coronal section of trunk, showing relations of thoracic and abdominal viscera. 
of anything which normally exists. The pleural cavity is virtual, and becomes 
actual only when some fluid (air, serum, pus) gets between the layers as a result THE LARYNX. 
767 
of accident or disease. In health only enough serous fluid is found between the 
layers to lubricate them and allow slipping of one upon the other with the least 
possible friction. 
The right pleura extends downward in the axillary line to the lower border 
of the ninth rib ; the left pleura goes to the border of the tenth rib, the greater 
thickness of the liver on the right side explaining the difference. The pleural 
sacs of the two sides nearly meet at the mid-line of the sternum. 
At the hilum of the lung the pulmonary pleura from above is reflected to 
the root, and thence to the mediastinal pleura; the visceral layers in front 
of and behind the vertical plane of the hilum not only cover the root, but 
come together directly beneath it, and form a double-layered, triangular sheet, 
extending vertically from the root of the lung to the diaphragm, and laterally 
from the lung to the mediastinal pleura. This fold is the broad ligament of 
the lung. 
The pleura upon the lung is delicate and so closely attached that it cannot be 
readily separated. The costal pleura is thick, and easily detached. The cervical 
pleura is liable to be injured in operations just above the clavicle. 
The visceral pleura is supplied by the bronchial arteries; the diaphragmatic 
and costal by the diaphragmatic and intercostal arteries ; and the mediastinal by 
the posterior mediastinal, bronchial, internal mammary, and superior diaphrag- 
matic. The nerves of the parietal pleura are the intercostal, pneumogastric, 
phrenic, and sympathetic; of the pulmonary pleura branches from the pulmonary 
plexus. 
THE LARYNX. 
The larynx is that portion of the air-passages which is so specially modified 
that it serves as the principal organ of voice. It connects the upper end of the 
trachea with the pharynx, and lies in front of the lowest segment of the latter, 
being itself thinly covered anteriorly by muscles, fasciae, and skin. It is the 
occasion of the protrusion (pomum Adami) which is plainly to be felt, and in 
adult males generally to be seen, in the middle of the fore part of the neck. Its 
framework consists of a series of firm cartilages, held to each other, to the wind- 
pipe and to the hyoid bone by ligaments, which permit varying degrees of motion. 
Mucous membrane, continuous with that of the pharynx above, and the trachea 
below, lines the larynx, the cavity of which is wide at both ends, but constricted 
in the middle in such a way that a median, fore-and-aft cleft, the glottis 
(rima glottidis, “ the cleft of the glottis ”) is produced. During ordinary, easy 
breathing, the cleft is wide open, and no noise is made ; but, if it is narrowed, 
voice is caused by the forcible discharge of air from the lungs, and the pitch is 
determined by the degree of the narrowing, a nearly complete closure resulting 
in a high tone, and a large separation determining a low one. The sides of the 
glottis are composed of fibrous bands, which are approximated and separated by 
the action of the muscles which cause movements of' the cartilages. These bands 
are known as the true vocal cords, and are the most essential portion of the organ- 
ism of the larynx, the work of other parts being directed to the production of 
proper attitudes in these cords. 
Besides its conspicuous function in the production of voice the larynx per- 
forms an important service in preventing the entrance to the air-passages below 
it of substances in process of being swallowed. This is accomplished mainly by 
the complete closure of the chink of the glottis. The same act, accomplished 
when the lungs are full, serves to prevent the expiration of the air, and thus to 
fix the diaphragm and make possible such compression of certain hollow organs 
of the abdomen as is necessary for the expulsion of their contents, as in defeca- 
tion, micturition, vomiting, parturition. 768 
THE ORGANS OF RESPIRATION. 
The Cartilages of the Larynx. 
The principal cartilages of the larynx are the cricoid, thyroid, arytenoid, and 
epiglottic. 
The cricoid cartilage (Fig. 828) is the lowest, and a firm union exists between 
it and the uppermost cartilage of the trachea. It derives its name from its 
ARYTCNCID ARTICU- 
LAR FACETS 
THYROID 
ARTIC.-" 
FACET 
Fig. 828.—Cricoid cartilage, front, right lateral, and rear views. (Testut.) 
resemblance to a finger-ring, and it is so placed that the signet of the ring is 
behind, its hoop in front. 
The thyroid cartilage (Fig. 829), so named from its resemblance to a shield, is 
UPPER 
CORNU 
UPPER 
CORNU 
lowerJ 
CORNU 
Fig. 829.—Thyroid cartilage, front and rear views. (Testut.) 
LOWER 
CORNU 
the largest of the set, and rests upon the cricoid. At each side it presents a 
squarish plate, and the two unite in a median line at the lower half of their front 
edges, leaving a deep notch above their line of union. The hind border of each 
CORNICULUM 
LA R Y N G I S 
CRICOID AR- 
TICULAR 
FACET 
VOCAL 
PROCESS 
VOCAL 
PROCESS 
Fig. 830.—Arytenoid cartilages, hind view. (Testut.) 
Fig. 831.—Arytenoid cartilages, front view. (Testut.) 
plate is projected downward in a process, and upward and backward in another 
process. 
The arytenoid cartilages (Figs. 830, 831), fancifully named “ pitcher-like,” are THE LARYNX. 
769 
two in number, are located upon the upper and back part of the cricoid, and are 
irregularly pyramidal in shape. Unon the summit of each is a corniculum 
laryngis (“ little horn of the lar- 
ynx somewhat cone-shaped, and 
bent backward and downward. 
(The cuneiform cartilages will be 
mentioned later.) 
The epiglottic cartilage (Fig. 832), 
situated, as its name implies, upon 
(or over) the glottis, is shaped like 
an oval leaf, its stem being received 
in the notch between the two wings 
of the thyroid. Its hind surface is 
concave above, and is convex 
below this, the prominence in the 
centre being called the cushion. 
The cricoid, the thyroid, and 
the arytenoids (except the apices 
of the last) are composed of pure 
cartilage ; the rest of the cartilages 
are of the yellow variety. The 
true cartilages are liable to ossify 
at any time after maturity is at- 
tained. At puberty the laryn x under- 
goes great changes of growth, which 
are ,especially marked in the male, 
and are prevented by castration. 
The position and relations of each of the cartilages are shown in Fig. 832. 
CORPUS 
TRITICEUM 
LATERAL THYRO- 
HYOID LIGAMENT 
Fig. 832.—Laryngeal cartilages and ligaments from be- 
hind. (Testut.) 
The Ligaments of the Larynx. 
The cartilages of the larynx are movably articulated with one another at 
various points. The lower cornua of the thyroid articulate with the raised oval 
facets on the outer side of the cricoid; the arytenoids are jointed with the surfaces 
at the upper and outer parts of the 
signet of the cricoid ; and the cornic- 
ula are usually attached to the apices 
of the arytenoid pyramids in such a 
way that motion is permitted. In 
all of these cases the movement is 
gliding, or rotary, or both, the car- 
tilages concerned in a joint are united 
by a capsular ligament, and the artic- 
ulation has a true synovial membrane. 
In addition to these there are 
numerous ligamentous bands, the most 
of them largely composed of yellow 
fibrous tissue, which serve to close in the 
gaps between nearly related cartilages, 
and by their elasticity to restore the 
connected parts when they have been 
displaced by the action of muscles. 
The names which these ligaments bear 
are suggestive of situation and action, 
as they are mostly composed of the 
names of the cartilages which they 
connect, and usually also contain some 
indication of their relative position. 
.LATERAL THYRO- 
HYOID LIGAMENT 
Fig. 833.—Laryngeal cartilages and ligaments from in 
ront. (Testut.) 770 
THE ORGANS OF RESPIRATION. 
The middle crico-thyroid ligament (Fig. 833) connects in front the upper 
border of the cricoid with the lower border of the thyroid. On each side this 
ligament is prolonged backward as the lateral crico-thyroid ligament (Figs. 834, 
835), which is attached below to the upper margin of the cricoid, but above, 
instead of running to the opposed edge of the thyroid, it slopes inward in its 
upward course, and is attached in front to the 
thyroid cartilage at the angle between the wings, 
behind to the anterior angle of the base of the 
INFERIOR 
-THYRO-ARYTENOID 
LIGAMENT 
THYROID 
CARTILAGE 
ARYT- 
ENOID 
CRICO-THYROID 
INF. THYRO-ARYtTIIgT 
CARTILAGE] 
LIGAMENT 
CRICOID 
CARTILAGE 
CARTILAGE 
CRICOID 
Fig. 834.—I>iagram of coronal section of lateral crico-thyroid 
ligaments. (F ,H. G.) 
Fig. 835.—Diagram of sagittal sec- 
tion of larynx, showing lateral crico- 
thyroid ligament of right side. (F. H. G.) 
arytenoid, and between these two points it is unattached. From its connections 
it would be more descriptively named crico-thryo-arytenoid. Its free margin, 
stretching between the thyroid and the arytenoid, is often called the inferior thyro- 
arytenoid ligament. This last is thick, flattened toward the middle line, and sharp 
on the upper edge. Covered with mucous membrane it constitutes one of the 
true vocal cords (Fig. 836). 
Close to the inferior is the superior thyro-arytenoid ligament, arising a little 
above it on the thyroid, and inserted upon the ridge on the front surface of the 
arytenoid. It is small, and with its covering of mucous membrane forms the 
upper or false vocal cord (Fig. 836). 
APEX OF SUP. HORN OF 
THYROID CARTILAGE 
l CORNICULUM 
ik LARYNGIS 
INFERIOR 
VOCAL CORD/ 
CARTI LAGE 
ARYTENO-EPIGLOT 
TIC FOLD 
APEX OF GREA 
HORN OF HYOI 
OF HYOID 
SUPERIOR 
VOCAL CORD 
LATERAL GLOSSO- 
EPIGLOTTIC FOLD 
MIDDLE GLOSSO- 
EPIGLOTTIC FOLD 
Fig. 836.—Larynx, viewed from above. (Testut.) 
From the cricoid to the inner, lower, and back part of the arytenoid is the 
c/rico-arytenoid ligament. The epiglottic cartilage is attached to the thyroid in the 
angle between its aim by the thyro-epiglottic ligament. Finally from the antero- THE LARYNX. 
771 
external surface of the arytenoid to the lateral border of the epiglottic cartilage 
runs the aryteno-epiglottic ligament, in which is usually found a small, yellow 
fibro-cartilage, called the cuneiform cartilage. 
All of these ligaments are in symmetrical pairs, except the middle crico- 
thyroid and the thyro-epiglottic, which are single and median, with bilateral 
symmetry. 
Besides these ligaments, which are called “ intrinsic ” from their forming a 
part of the larynx, there are others which connect it with the hyoid bone above 
and the trachea below, and are named “ extrinsic ” on account of their situation 
outside of the larynx (Fig. 833). The connection between the larynx and trachea 
is almost precisely like that between neighboring cartilages of the latter. From 
the anterior notch of the thyroid to the body of the hyoid extends the somewhat 
elastic middle thyro-hyoid ligament; and from the upper edges of the alse and 
front margins of the superior horns of the thyroid to the lower borders of the 
great cornua of the hyoid stretch the very elastic lateral thyro-hyoid ligaments, 
each perforated by the superior laryngeal vessels, and having in its hind edge a 
little bit of cartilage, the corpus triticeum (“ wheat-like body ”). 
The Muscles of the Larynx. 
The muscles of the larynx, like its ligaments, are divided into two groups— 
the extrinsic, which are outside of, but act upon, it; and the intrinsic, which are 
attached at both ends to parts of the larynx, and move these parts upon each 
other. The former are the sterno-thyroideus, thyro-hyoideus, stylo-pharyngeus, 
palato-pharyngeus, and constrictor inferior pharyngis, and are described in other 
places. The intrinsic are the following: Crico-thyroideus, crico-arytenoideus 
posterior, crico-arytenoideus lateralis, thyro-arytenoideus, thyro-epiglottideus, 
aryteno-epiglottideus, arytenoideus. 
All of these muscles are in symmetrical pairs, except the last, which is single, 
but bilaterally symmetrical. Their 
names are a guide to their situation, 
and suggestive of their action. They 
are members of the rather small class 
of muscles whose names are almost 
invariably Anglicized among English- 
speaking people, generally by the elimi- 
nation of the terminal eus, and, in the 
case of the third, of the last two let- 
ters of lateralis also. They are so 
plainly exhibited in the figures that 
elaborate description is unnecessary. 
Normally, they always act in pairs, 
and their action affects two things—the 
width of the aperture of the glottis, and 
the tension of the true vocal cords. 
The crico-thyroid muscle (Fig. 837) 
arises from the lower border of the ala 
of the thyroid and the front edge of its 
lower horn, con verges down ward and for- 
ward, and is inserted into the front and 
side of the cricoid. The thyroid being 
fixed, the anterior part of the pair of 
muscles lifts the front of the cricoid 
upward, and the portion of the cricoid 
behind the crico-thyroid articulation is, consequently, tilted downward, and, as 
this carries the arytenoids with it, the true vocal cords are tightened. The hind 
STERNO- 
THYROIDEUS 
Fig. 837.—Muscles of larynx, front view. The 
sterno-thyroids and right thyro-hyoid have been re- 
moved. (Testut.) 772 
THE ORGANS OF RESPIRATION. 
part of the muscle contributes to this result by drawing the cricoid backward. 
Nerve, the superior laryngeal. 
The posterior crico-arytenoid muscle (Figs. 838, 839) arises from nearly a 
lateral half of the hind surface of the cricoid, and converges to the outer angle 
of the base of the arytenoid, into which it is inserted. The two muscles draw 
their points of insertion backward and toward each other, and thus cause a diver- 
gence of the anterior processes and the vocal cords which are attached to them. 
Nerve, the inferior laryngeal. 
The lateral crico-arytenoid muscle (Fig. 838) arises from the side of the upper 
border of the cricoid, passes upward and backward, and is inserted into the exter- 
ARYTENOIDEUS- 
_C RICO-ARYTENOI* 
~ DEUS LATERALIS 
Fig. 838.—-Muscles of larynx, right side. The right ala of the thyroid cartilage has been cut through and 
turned down. (Testut.) 
rial angle of the arytenoid. The two cause approximation of the vocal cords by 
pulling the external arytenoid angles forward and downward, thus turning the 
anterior angles inward. Nerve, the inferior laryngeal. 
The thyro-arytenoid muscle (Fig. 838) consists of an internal portion, which 
occupies the most of the triangular space included in the mucous fold enwrapping 
the true vocal cord ; and a broad, external portion, flattened laterally against the 
inner surface of the thyroid ala. It arises from the lower half of the hind sur- 
face of the thyroid near its angle, and from the adjacent surface of the crico- 
thyroid ligament. It converges backward, outward, and upward, and is inserted 
(internal part) into the vocal process and (external part) into the adjacent por- 
tion of the outer surface and the outer angle of the arytenoid. The pair draws 
the arytenoids forward, relaxing the vocal cords. Nerve, the inferior laryn- 
geal. 
The thyro-epiglottic muscle (Fig. 838) arises from the thyroid, just above the 
thyro-arytenoid, passes upward and backward, and is inserted into the side of 
the epiglottic cartilage. It depresses the epiglottis. Nerve, the inferior laryn- 
geal. THE LARYNX. 
773 
The aryteno-epiglottic muscle (Fig. 838) arises near the apex of the arytenoid, 
passes forward and upward, and is inserted into 
the side of the epiglottic cartilage. With its 
mate it draws the epiglottis backward and 
downward. Nerve, the inferior laryngeal. 
The arytenoid muscle (Fig. 838) (ary-ary- 
tenoid) connects the two arytenoid cartilages, 
being attached to the outer half of the con- 
cavity on the back of each. The ventral fibres 
are transverse, but the dorsal are arranged in 
two oblique bundles, which cross each other, 
and are continued into neighboring muscles— 
the thyro-arytenoid, aryteno-epiglottic, and 
lateral crico-arytenoid—as well as inserted 
each into the highest part of the opposite 
arytenoid cartilage. The muscle draws the 
arytenoid cartilages together, thus closing the 
part of the rima glottidis included between 
them. Nerves, the superior and inferior lar- 
yngeal. 
It will be observed that the arytenoid mus- 
cle has both the superior and inferior laryngeal 
nerves distributed to it; the crico-thyroid the 
superior only; and all of the other muscles the 
inferior only. 
Fig. 839.—Muscles of larynx, from be- 
lind. (Testut.) 
Mucous membrane lines the larynx throughout. It is continued from the 
mucosa of the tongue and pharynx, extends over the epiglottic cartilage and 
from the aryteno-epiglottic ligaments downward and inward to the superior thyro- 
arytenoid ligaments, which it 
covers on their median and 
under surfaces, constituting 
with them the superior, or 
false, vocal cords. The mem- 
brane is continuous below with 
that of the trachea, and lines 
the inner surface of each of 
the lateral crico-thyroid liga- 
ments and the inner and upper 
surfaces of the thyro-arytenoid 
ligaments, which with it com- 
pose the inferior, or true, vocal 
cords. Between the false and 
true vocal cords of each side 
is a narrow horizontal opening 
of fusiform outline, the aper- 
ture of a cavity, called the 
ventricle of the larynx, which 
extends outward and then 
bends upward just on the 
mesial side of the upper part 
of the thyro-arytenoid muscle, 
and is lined with mucous 
membrane prolonged from that 
of the vocal cords. From the front of the ventricle extends upward a laryngeal 
pouch (sacculus laryngis), which is narrow, long, and embedded in fat. 
The Lining of the Larynx (Figs. 840, 841) 
ARYTENO- 
:piglottideus 
L_ INFERIOR 
VOCAL CORO 
CRICO- 
THYROIDEUS 
Fig. 840.—Coronal section of larynx, rear view of front half! 
(Testut.) 774 
THE ORGANS OF RESPIRATION. 
The mucosa is pale and thin, especially upon the true vocal cords. In most 
parts its epithelium is columnar and ciliated, but just above the false vocal cords 
it becomes flattened and stratified, and it is of this kind also upon the true vocal 
HYOID— 
_ARYTENO-EPI- 
FOLD 
THYRO-HYOIDEUS 
THYRO-EPIG LOT - 
TIC LIGAMENT 
THYROID 
CARTI LAGE 
CRICOID 
"CARTILAGE 
CRICOID 
CARTILAGE" 
Fig. 841.-—Sagittal section of larynx, right half. (Testut.) 
cords, and in small areas elsewhere. Beneath the membrane in the aryteno-epi- 
glottic region is a good deal of loose areolar tissue. Mucous glands are numerous 
and large, excepting on and about the true vocal cords. 
APEX OF SUP. HORN OF 
THYROID CARTILAGE 
CORNICULUM 
LARYNGIS 
CUNEIFORM 
k CARTILAGE 
INFERIOR 
VO CAL CORD 
ARYTENO-EPIGLOT- 
TIC FOLD 
APEX OF GREAT 
HORN OF HYOID 
SUPERIOR 
VOCAL CORD 
LATERAL GLOSSO- 
EPIGLOTTIC FOLD 
MIDDLE GLOSSO- 
EPIGLOTTIC FOLD 
Fig. 842.—Larynx, viewed from above. (Testut.) 
Viewing the larynx from above (Fig. 842), an upper opening is seen, its 
front wide and semicircular, its sides drifting together behind and below in an 
undulating curve. The anterior boundary of this aperture is made by the epi~ 775 
THE LARYNX. 
glottis, the downward-sloping sides by the aryteno-epiglottic folds of mucous 
membrane, which run from the sides of the epiglottis to the tops of the arytenoid 
cartilages, and are nodulated by the cuneiform and corniculate cartilages. 
Through this wide aperture are seen in front the backward projection from the 
surface of the epiglottis called its cushion; on the sides, diverging backward and 
outward, the upper or false vocal cords ; farther down in the cavity and nearer 
the median line the true vocal cords, and, on a level with them, the inner margins 
of the bases of the arytenoid cartilages; and finally, occupying the middle line 
and a little space on each side of it, the rima glottidis. This chink of the glottis 
is about an inch in its fore-and-aft measurement, the front two-thirds of this 
being bounded laterally by the true vocal cords, the hind third by the arytenoid 
cartilages. The portion between the vocal cords is called the vocal part, from its 
function in the production of voice; the portion between the arytenoids is known 
as the respiratory part, on account of its use in the process of breathing. THE URINARY SYSTEM 
F. H. GEREJSH. 
THE doable function of appropriation and elimination belongs both to the ali- 
mentary and to the respiratory systems, each being concerned in the supply 
of new material, and also in the casting off of effete substances. But the urinary 
system is simply excretory : its only office is relieving the body of certain waste 
products, which, if allowed to remain in it, would injure the organism, and ulti- 
mately destroy life. 
The organs of the urinary system are the two kidneys, which form the urine 
from materials furnished by the blood; the ureters, ducts which convey the urine 
away from the kidneys; the bladder, a reservoir in which the urine is stored 
until circumstances are convenient for its discharge ; and the urethra, a tube 
through which the urine passes from the bladder, and is finally voided. 
THE KIDNEYS. 
The essential organs of the urinary system are the kidneys. The materials 
which they abstract from the blood are in solution in water, and this solution is 
the urine. The formation of this fluid is constant; and, as fast as it is produced, 
it is conducted to the bladder. In some details of gross anatomy the two kid- 
neys differ slightly, as will be related subsequently ; but functionally they are 
identical, and the physiological anatomy of one is exactly like that of the other. 
A kidney is a compound, tubular gland—a vast multitude of microscopic 
tubes, all lined with epithelial cells, and abundantly supplied with blood-vessels. 
The study of a single one of these tubes reveals the physiological anatomy of the 
kidney, and with that it is best to begin. 
A uriniferous tube starts as a hollow globe (the capsule) ; then come in regular 
succession a constricted part (the neck), a tortuous (the proximal convoluted tube), 
an undulating and twisted (the spiral tube), a long portion bent so abruptly near 
its middle that the two parts are parallel (the looped tube), a portion with a zig- 
zag contour, full of short lines and marked angles (the irregular tube), a second 
tortuous part (the distal convoluted tube), a short, arching part (the junctional or 
arched collecting tube), and, finally, a long portion (the straight collecting tube), 
the wide, terminal part of which is called the excretory tube.1 
The various parts of this long tube differ not only in shape and direction but 
in diameter. All of these features will be seen in the part of Fig. 846, at the 
extreme left. 
Structure of a Uriniferous Tube.—The tube is composed of a basement mem- 
brane and a single layer of epithelial cells, which rest upon it and vary in form 
according to their situation. In most narrow portions of the tube and in the 
capsule they are flattened ; in the neck and collecting tubes they are cuboidal or 
columnar; and elsewhere they are somewhat cuboidal and granular toward the 
1 The capsule is called also the capsule of Bowman, the looped tube is known as Henle’s, the 
irregular bears the name of Schachowa, and the excretory is known as the duct of Bellini. 
777 778 
THE URINARY SYSTEM. 
bore (this part containing a large nucleus), and toward the membrane they look 
like a mass of rods and their sides are grooved. Where the tube is not very 
small, the lumen occupies only about one-third of the entire diameter on account 
of the relative thickness of the cells. 
The tube is enveloped in a network of blood-vessels, from whose contents its 
cells abstract the ingredients of the urine. The vascular apparatus will be 
described later on. 
Lobes of the Kidney.—lt has been estimated that each kidney contains about 
half a million capsules, and fifteen miles of tub- 
ing. The disposition of this vast number of 
tubes is very intricate, and yet so regular as to 
produce practically invariable gross appearances 
in ditferent parts of the compound organ. In 
some lower animals the kidney, instead of being 
a single, coherent mass, consists of a number of 
similar lobes, so slightly united that the appear- 
ance of the organ suggests a bunch of grapes. 
A condition approaching this obtains in the human 
embryo, though the independence of the lobes is 
not as marked (Fig. 843). The study of the 
naked-eye appearances of a separate lobe is neces- 
sary to an understanding of the arrangement of 
the tubes. 
An Ideal Lobe.—Each lobe is like a cone 
whose apex has been cut off, and its place sup- 
plied by the apex of a smaller cone (Fig. 844). 
A vertical section through the middle of this 
cone brings to view a cut surface in which are seen two apparently distinct kinds 
of material (Fig. 845). Within is a triangular portion, red and streaked with 
alternating dark and light lines from base to apex ; and, enclosing this, except at 
Pig. 843.—Foetal kidney, showing 
lobes. (Testut.) 
CORTEX 
MARGINAL ZONE 
MEDULLA 
\ PAPILLAR Y , 
ZONE 
Fig. 844.—Diagram of a lobe of the kidney. 
(F. H. G.) 
Fig. 845.—Diagram of a vertical section of a lobe 
of the kidney. (F. H. G.) 
the apex, is a thick, lighter colored, granular part. The former is the medulla 
(“ the pith ”), or medidlary pyramid; the latter is the cortex (“ the bark ”), or 
cortical portion. Reckoning from the base to the apex of the lobe, the cortex 
occupies a little more than a third of the distance. A fibrous capsule covers it, 
and a thin stratum of the cortex just beneath this is called the snbcapsular layer. 
The pyramid is divided into two parts—a smaller called the papillary zone, from 
its including the apex (papilla), and a larger, known as the marginal, boundary, 
or limiting zone, this being darker and more distinctly striated. Intruding from THE KIDNEYS. 
779 
CAVITY OF CALYX 
Fig. 846.—Diagram of the structure of a lobe of the kidney. The lobe is seen in vertical section, the cortex 
being marked off from the medulla. Four medullary rays encroach upon the cortex. At the left is shown the 
course of a single, continuous series of tubes—the straight and spiral tubes appearing in the medullary ray, 
the straight, looped, and excretory in the medulla proper, the capsule, neck, convoluted, irregular, and arched 
in the cortex proper. Next is seen the labyrinth, composed of a mass of tubes in the cortex, with a medullary 
ray for a centre. Equidistant from the ray on each side is a broken red line, marking the position of an inter- 
lobular artery. The parts between these lines constitute a lobule. Farther to the right is an interlobular 
artery, giving off lateral branches (afferent vessels), each of which ends in a tuft of capillaries, from which the 
blood is collected by an efferent vessel . The uppermost of the tufts is shown enclosed in a capsule. On the 
right of the interlobular artery the efferent vessels break up into a capillary network, which surrounds the 
(unrepresented) tubes in the cortex and ray. The lowest efferent sends vertical vessels also into the medulla. 
On the right the interlobular vein is seen gathering the blood from all the parts supplied by the interlobular 
artery. A branch of the renal artery courses upward between cortex and medulla, and forms an arch (here 
broken) over the base of the medulla. From it the interlobular arteries pass upward into the cortex, and 
straight branches go downward into the medulla, supplying its structure, and ending at the apex in the capil- 
laries. From the last the radicles of the renal vein arise, and accompany the straight arteries to the base of the 
medulla, where a venous arch is formed, continuous with which is the vena comes of the entering artery. The 
calyx embraces the apex of the medullary pyramid. It is lined with epithelium, which continues from it over 
the apex, the latter being perforated with the many apertures of excretory tubes. 780 
THE URINARY SYSTEM. 
the medullary portion into the cortical are a number of narrow triangles, their 
bases resting on the base of the pyramid, and their apices reaching nearly to the 
subcapsular layer. They are called medullary rays (pyramids of Ferrein), on 
account of their radiation from the medulla. 
The diagram (Fig. 846) will show that these various appearances are due prin- 
cipally to the arrangement of the different portions of the tubes. It will be seen 
that in the medullary rays are all of the spiral tubes, and the uppermost parts 
of the straight collecting tubes and of the ascending limbs of the looped tubes 
(distal spiral tubes), these being placed side by side in line with the chief axis of 
the ray, the longest being in the middle. In the remaining and greater part of 
DESCENDING LIMB OF 
HENLE’S TUBE j 
CONNECTIVE TISSUE 
BLOODVESSEL 
ASCENDING LIMB OF 
I HENLE’S TUBE 
Fig. 847.—-Transverse section of kidney, made in the marginal zone—greatly magnified. Observe the amount 
of the interstitial connective tissue. (Testut.) 
the cortex are the capsules and their necks, and the convoluted, irregular, and 
arched collecting tubes, all so intricately intermingled as to produce the granular 
look of the part, and to merit the name of labyrinth. The medulla contains the 
greater part of the length of the looped and of the collecting tubes; and, as these 
are straight and side by side, the delicate striation of the medulla is explained. 
Tire broad alternating dark and light streaks in the pyramid are due to a vascular 
distribution as will presently be seen. 
The Vessels of the Kidney.—The arteries enter the Jobe in the cortical sub- 
stance at the sides of the pyramid. When they reach the level of the base of 
the pyramid, they turn inward and run across between the medullary and cortical 
portions, constituting the arterial arches, and giving branches upward into the 
cortex, and, according to most authorities, branches downward into the medulla. 
The branches to the cortex, called interlobular, enter the cortex half way between 
the medullary rays, and give off short side-twigs, the afferent vessels (“the vessels 
carrying to ”), each of which terminates in a globular bunch of capillaries, the 
glomerulus, or Malpighian tuft. This tuft is commonly described as being inside 
of the capsule, which is the beginning of a uriniferous tube, and, in one sense, 
this is correct. But, from the physiological point of view, the tuft is outside of 
the capsule; for it is related to it only as if it had pushed in and stretched 
the capsular wall at a point opposite the neck, carrying everything before it until 
the cavity was nearly obliterated. The cells now lining the capsule are compar- 
able with the parietal layer of a. serous membrane, and those covering the glom- 
erulus with its visceral layer. The capsule and tuft together are called the Mal- 
pighian body. The blood leaves the tuft through a vessel, called efferent (“ carrying THE KIDNEYS. 
781 
from ”), which emerges beside the afferent. It is probably an artery, although it 
is often spoken of as a vein. It breaks up into a close capillary plexus, which 
surrounds the secreting tubes in the cortex. From this network come venous 
radicles, which empty into minute veins, the interlobular, accompanying the inter- 
lobular arteries. These veins terminate in venous arches between the cortex and 
medulla, and thence leave the lobe by the track taken by the artery in entering. 
The lowest efferent vessels give pencils of capillaries to the tubes in the medulla. 
The branches from the under side of the arterial arches, always accompanied 
by corresponding radicles of the venous arches, lie between the tubes of the pyra- 
mid in regular parallel groups, producing the darker lines in the alternating 
series of stripes of the boundary zone. These vessels are named vasa recta. On 
their way to the papilla the arterioles give capillaries to the tubes, and at the 
papilla these end in venous radicles, which run straight up to the suprapyraraidal 
venous arches. 
The vessels in the cortex, which run vertically to the vascular arches, mark the 
limits of the primary lobules of the labyrinth, and hence are called “interlobular.” 
A transverse section of the cortex shows the lobulation, each lobule having a cir- 
cular bundle of tubes, the medullary ray in its centre, and a tangled mass of 
tubes around it. 
At the apex of the papilla the uriniferous tubes end as the excretory tubes 
(ducts of Bellini) in from ten to eighty openings, called foramina papil/aria, 
producing the appearance of the nozzle of a watering-pot, through which the 
urine constantly trickles. As it escapes it is received into the upper end of the 
excretory duct of the lobe, which is here expanded and resembles a cup, from 
which it is named the calyx. The rim of the calyx is attached around the base of 
the papilla. The surface of the papilla is covered with mucous membrane, which 
is continuous with that lining the calyx and the rest of the excretory duct. 
Framework of the Kidney.—The capsule which covers the lobe is a condensed 
areolar tissue, which is continuous with that clothing the calyx, and immediately 
beneath it is a delicate stratum of unstriped muscular tissue. Quite a bundle of 
this last material surrounds the pyramid just above the attachment of the calyx. 
The tubes and vessels are supported by interstitial connective tissue, which is 
small in amount, except around the Malpighian bodies and in the papillary region. 
It is condensed at the surface, where it is intimately connected with the true 
capsule. 
Coalescence of the Lobes (Fig. 848).—There are from eight to twenty lobes in 
a kidney, and each of them answers to the foregoing description. Beginning as 
separate parts, they afterward coalesce at their adjacent surfaces, and the fusion is 
so perfect that the included portions of the tunic disappear, and the lines of con- 
tact cannot be traced. The apices of the lobes converge, and the papillae project 
into a central cavity, the sinus. A section of the kidney after the union of its 
lobes shows that the pyramids are separated by masses of cortical substance, the 
columns of Berlin, and that there is more of this between the pyramids than there 
is elsewhere. The incongruity of calling that part of an organ its bark, which is 
mostly not on the outside, is not dissipated until one learns that the name “ cor- 
tex” is applied primarily to the outer layer of renal substance in the individual 
lobes—a use of the term eminently descriptive in the circumstances—and it is not 
abandoned when the lobes are fused. The part of the cortex, whose title to the 
name in the compound kidney no one would think of disputing, presents in verti- 
cal section the appearance of curving across the base of each pyramid from one 
column to another, whence the name cortical arches. 
The coalescence of the lobes often goes so far that the apices of two pyramids 
become fused into one, their bases continuing separate ; so that in a kidney with 
fourteen pyramids there may be only ten papillae. 
Gross Features of the Kidney (Figs. 849, 850).—The kidney (in Latin ren, 
from which comes the adjective “ renal ”), made up of lobes as just described, 
is somewhat bean-shaped, presenting a convex front surface, and a flattened back 782 
THE URINARY SYSTEM. 
...COLUMN OF 
BERTIN 
MEDULLARY 
PYRAMID 
/....MEDULLARY 
PYRAMID 
URETER 
COLUMN OF 
BERTIN 
Fig. 848 —Vertical section of kidney, showing the secreting portion, the vessels, and the beginnings of the 
ureter. (Testut.) 
surface; rounded upper and lower ends, the former being a little the larger ; a 
convex outer border, and an inner border, which has a notch, called the hilum. 
SUPERIOR SUPRA- 
RENAL ARTERY 
SUPERIOR SUPRA- 
RENAL ARTERY 
URETER' 
URETER 
Fig. 849.—Right kidney, ventral aspect. (Testut.) 
Fig. 850.—Right kidney, dorsal aspect. (Testut.) 
The hilum presents a vertical cleft, with rounded front and back lips, and this is 
the narrowed entrance to the cavity (sinus) of the kidney. The sinus is a deep THE KIDNEYS. 
783 
excavation, flattened from before backward, and reaching half way from border to 
border. The papillae project into it, and it encloses the divisions of the renal 
vessels, the beginnings of the excretory apparatus, lymphatic vessels and nodes, 
nerves, and a quantity of adipose tissue, which fills the spaces left unoccupied by 
these structures, and affords an elastic bed upon which they rest. The outer 
tunic extends into the sinus through the hilum, becomes continuous with the 
sheaths of the vessels, and is reflected onto the calices. 
The kidney is about 4| inches long, 2| inches wide, and inch thick. It 
weighs from 4to ounces. Its surface is smooth, no traces of the foetal separa- 
tion of the lobes remaining. It is of a reddish-brown color. It has a firmer 
consistence than either liver or spleen, but is lacerated by moderate force. 
The artery of the kidney is the renal, and is large relatively to the size of the 
organ it supplies (Fig. 851). It divides into four branches, which pass into 
the sinus, and then break up into vessels, which enter the columns of Bertin, 
and pursue a course, which has already been described. The surface of the kid- 
ney receives small branches from the suprarenal, spermatic, and lumbar arteries. 
The veins course side by side with the arteries. The lymphatic vessels are numer- 
Fig. 851.—The kidneys, the ureters, and the bladder, in their normal position. (Testut.) 
ous, especially in the labyrinth, and there are several nodes in the sinus. Both 
the superficial and deep lymphatics are tributary to the lumbar nodes. The renal 
nerves come from the renal plexus and small splanchnic. They accompany the 
arteries, but have not been traced beyond the interlobular. Some fibres from the 784 
THE URINARY SYSTEM. 
pneumogastric, also, have been observed. About two-thirds of the anterior sur- 
face is invested with 'peritoneum. 
Situation of the Kidneys.—The kidneys are situated at the back of the abdo- 
men, one on each side of the spinal column, behind the peritoneal cavity, on a 
level with the bodies of the twelfth thoracic and upper two or three lumbar ver- 
tebrae, the right being about one-half inch lower than the left. The long axis of 
each is directed from above downward and a little outward, so that the upper ends 
are nearer the middle line than are 
the lower. Their hind surfaces look 
backward and inward. Their lower 
ends are two inches or less above the 
iliac crests. 
Supports of the Kidneys.—The kid- 
neys are kept in place by their ves- 
sels, the peritoneum, and the abund- 
ant fatty tissue in which they are 
embedded, and which constitutes the 
“adipose capsule” of some authors. 
Relations of the Kidneys (Fig. 
852).—The upper end of each kidney 
is capped by a suprarenal body, which 
laps over upon the front surface and 
inner border. The hind surface of 
each is in relation to the last rib, the 
diaphragm, and the quadratus lum- 
borura and psoas magnus muscles. 
The anterior surface of the right kid- 
ney is related from above downward 
to the suprarenal body, liver, duode- 
num, ascending colon, and jejuno- 
ileum ; the anterior surface of the left 
kidney to the suprarenal body, spleen, 
stomach, pancreas, splenic flexure, 
descending colon, and jejuno-ileum. 
OUTER BORDER OF# 
QUADRATUS / 
> OUTER LINE' 
lof ERECTOR 
• . 
THE EXCRETORY APPARATUS 
OF THE KIDNEYS. 
Fig. 852.—Relations of the left kidney to the lung, 
pleura, ribs, spine, muscles, and hip-bone. (Testut.) 
The urine is conducted from the 
kidneys by the ureters, by them 
poured into the bladder, and finally 
discharged from this reservoir through the urethra 
The Ureters. 
The ureter for each kidney begins with the calices which enclose the papillae. 
They are somewhat fewer than the papillae, because one calyx may embrace two 
or even three of them. By the convergence and union of the calices in the upper, 
middle, and lower regions of the sinus respectively three funnel-shaped tubes, the 
infundibula, are formed ; and these focus upon and empty into a large dilatation, 
the pelvis (“basin”), which terminates in the ureter proper. The pelvis lies 
partly within and partly outside of the sinus. When seen from front or back its 
form is suggestive of the bowl of a tobacco-pipe, the tubular ureter standing for 
the stem ; but it is much compressed antero-posteriorly, having to emerge from 
the sinus through the hilum, which, although but a narrow slit, gives passage also 
to the renal vessels, the latter lying in front of the pelvis. The ureter proper is 
as large as a small goose-quill, about 14 inches long, and passes downward and THE BLADDER. 
785 
inward to the upper level of the sacrum, and thence forward and inward to the 
base of the bladder, whose outer coat it perforates, and running obliquely between 
this and the inner tunic for three-quarters of an 
inch, opens into the cavity of the bladder by a nar- 
row slit, which is one and a half inch or less from 
its opposite fellow and from the beginning of the 
urethra (Fig. 853). The practical effect of this 
arrangement is to prevent the reflux of urine from 
the bladder; for, although the admission of the 
fluid is not interfered with, distension of the blad- 
der so presses together the sides of the channel that 
not a drop can return to the ureter. 
Structure of the Ureter.—The ureter has three 
coats : an inner or mucous, a middle or muscular, 
and an outer or fibrous. The mucous coat is con- 
tinuous with that of the bladder below and with 
that covering the renal papillae above. Its epithe- 
lium is stratified, the upper layer consisting of cuboidal cells, with concavities on 
their attached surfaces, into which fit the blunt ends of the pyriform cells next 
below, the taper ends of the latter fitting in between the processes of fusiform 
cells underlying them, and last of all a stratum of irregular cells. There is no 
well-defined submucous coat. The membrane displays longitudinal folds. The 
muscular tunic has two layers, an outer longitudinal and an inner circular. The 
fibrous coat is a mixture of the white and yellow varieties ; it is continuous with 
the renal capsule, which, entering at the hilum, is reflected upon the calices. The 
ureter is surrounded by areolar tissue. 
Branches from the renal, spermatic, internal iliac, and inferior vesical arteries 
supply the ureter, its veins correspond to these, its lymphatics run to the pelvic 
and lumbar nodes and to the receptaculum chyli, and its innervation comes 
through the inferior mesenteric, spermatic, and hypogastric plexuses. 
In its descent the ureter is behind the peritoneum all of the way. 
The pelvis is opposite the spine of the first lumbar vertebra. Behind the 
ureter are the psoas muscle, the sacro-iliac synchondrosis, and the common or 
external iliac vessels. It is covered in front by the spermatic vessels, and the vas 
deferens runs between it and the bladder. The right ureter has the vena cava 
inferior at its inner side. In the female the ureter courses beside the cervix uteri, 
but at the distance of nearly or quite half an inch, and then it obliquely crosses 
the upper third of the vagina. 
Fig. 853.—Diagram showing meth- 
od of entrance of the ureter into the 
bladder. (F. H. G.) 
The Bladder. 
The bladder (-vesica urinaria, “the urinary bladder,” always being meant 
when the noun is not qualified) is the reservoir in which the urine is collected 
from the ureters, and contained until a convenient time for evacuation. It has 
four tunics :'the mucous, which is that nearest the cavity, and then in order the 
areolar, the muscular, and the serous. The mucosa, has a stratified epithelium, 
similar to that of the ureter, is loosely attached to the muscular coat by the 
areolar, is deficient in well-defined glands and in muscularis mucosse, is smooth 
when spread out by accumulation of urine, but, during the empty condition is 
thrown into irregular rugae, excepting in a small, triangular space (trigonum) 
between the openings of the ureters and the urethra. This little area is never 
wrinkled, but is marked in the median line by a slight ridge, the uvula vesica. 
The muscular tunic has an outer, longitudinal layer, which runs sagittally; inside 
of this a stratum in which the fibres are intricately and irregularly criss-crossed, 
but have a general transverse (circular) direction, and internal to this an imperfect, 
thin, longitudinal layer. The serous coat is a reflection of the peritoneum, and is 
only a partial tunic, covering the superior surface, and the upper and hind part 786 
THE URINARY SYSTEM. 
of the lateral surfaces, and, in the male, the upper part of the posterior surface. 
The thickness of the combined walls varies much within normal limits, being 
small in distension, great in collapse, and especially marked if there is good tone 
to the muscular coat. 
Form, Size, and Position of the Bladder.—Without regarding several widely 
varying, normal circumstances, it is impossible to speak definitely of the form, 
size, position, and relations of the bladder. One must know the sex and approxi- 
mately the age of the individual, whether 
the organ is empty, rather full, or dis- 
tended, the condition of the muscular coat, 
and the fact as regards pregnancy. When 
the bladder is collapsed, its mucous walls 
fall together in such a way that a sagittal 
section shows the line between them in 
the shape of a V with unequal and widely- 
spread arms, the point of the V indicating 
the opening of the urethra (Fig. 854). 
This view affords a means of designation 
of the most important surfaces. The 
part included within the arms of the V 
we call superior or intestinal surface; 
that beneath the long arm the anterior or 
pubic surface; and that under the short 
arm, the posterior or rectal surface. 
Besides these are right and left lateral surfaces, which are narrow when the 
organ is empty. 
When the bladder is moderately full, its sagittal section is very different (Fig. 
855). The upper surface has changed from concavity to convexity, all of the 
others have become rounded, and the angles between the surfaces have vanished. 
The bladder in these circumstances holds about eight fluidounces, and has not 
risen out of the pelvic cavity. But, if this amount of urine is much exceeded, 
the limit of comfort is passed, and pronounced distention obtains, lifting the 
organ above the pelvic brim to a height 
commensurate with the degree of ful- 
ness, and bringing it within reach of 
recognition by abdominal percussion. In 
the female the bladder is flattened from 
behind forward, increasing the lateral and 
diminishing the antero-posterior diame- 
ters. In the child the bladder is almost 
an abdominal organ ; but, with increase 
of years, it sinks to its adult position in 
the pelvis. 
The orifice of the urethra is at the 
lowest point of the bladder, and is about 
an inch behind the middle of the pubic 
symphysis. In old men the posterior wall 
is liable to sag below this level, and thus 
permit the retention of a portion of the 
urine. Enlargement of the prostate gland 
causes a bulging into the vesical cavity, 
and raises the opening high above the surrounding walls. There is no constricted 
part of the bladder which is entitled to be called a neck : the vesical opening of 
the urethra (meatus urinarius internus) is not funnel-shaped, but occurs as an 
abrupt aperture. 
Supports of the Bladder.—The bladder is rather freely movable, but is held 
within normal limits in various ways. The recto-vesical portion of the pelvic 
/rectum. 
/anus 
Fig. 854.—Diagram showing the shape, position, 
and relations of the bladder, when empty. (F. H. G.) 
CAVITY OF 
\ BLADDER 
/rectun^ 
'ANUS 
Fig. 855.—Diagram showing the shape, position, 
and relations of the bladder, when distended. (F. 
H. G.) THE URETHRA. 
787 
fascia is an important means of fixation. Around the lower levels of the bladder 
this fascia is closely united to the muscular tunic, and is sometimes spoken of as 
a covering of the bladder, thinning out rapidly as it stretches upward. Several 
parts of tliis fascia are conventionally described as true ligaments of the bladder— 
two anterior, two lateral, two posterior—but they are usually indistinct, and it is 
not important to mention more than the two anterior or pubo-prostatic, which 
connect the lower part of the pubic body with the front of the prostate gland and 
the adjacent portion of the bladder. Just beneath each of these is a prolongation 
of the front and lower part of the longitudinal muscular layer, called the vesico- 
pubic muscle, connecting bladder and pubis. The urachus and the obliterated 
hypogastric arteries extend from the junction of the upper and anterior surfaces 
to the umbilicus. Folds of peritoneum aid in mooring the bladder, two posterior 
being reflected to it from the sides of the rectum, the hollow between them being 
called the recto-vesical pouch ; two lateral from the iliac fossae; and one superior, 
folded over the urachus. These serous reduplications are called false ligaments. 
The continuity of the vesical, prostatic, and ureteral mucous membranes, the 
strong areolar and adipose connections of the bladder with all of the immediately 
neighboring organs, and the blood-ves- 
sels—all these are factors in the fix- 
ation of the bladder. 
Relations of the Bladder.—The pre- 
vious description has involved inci- 
dentally so much mention of the 
relations of the bladder that but little 
more need be said of them. Its poste- 
rior surface, which is the widest, rests 
in the male upon the rectum (Fig. 856). 
The serous covering of the superior 
surface extends for a variable distance 
upon the posterior, and thence is re- 
flected to the rectum. The line of its 
lowest attachment to the bladder forms 
the base of a triangle, whose sides are 
made by the vasa deferentia. The area 
thus bounded is accessible to surgical 
operation through the rectum ; but it is 
unsafe to count upon more than an inch 
of non-serous surface in the median line 
between the hind limit of the prostate gland and the fold of peritoneum, though 
there may be double this amount. In the female the bladder has behind it the 
vagina and uterus. 
When the bladder is distended, the anterior (pubic) surface is so enlarged that 
it partly rises out of the pelvis, and at the same time the peritoneum is lifted 
away from the lower part of the abdominal wall, and stretched over the extended 
area of the superior surface. This leaves a space of two inches or more just above 
the pubic crest in which an incision can be made without injuring the peritoneum. 
The arteries of the bladder are the superior and inferior vesical, and, in the 
female, the uterine also; its veins are radicles of the internal iliac ; its lymphatics 
are tributary to the internal iliac nodes ; and its nerve-supply is from the third and 
fourth sacral, and the hypogastric plexus of the sympathetic. 
Fig. 856.—Base of the bladder, showing the vasa 
deferentia and seminal vesicles. The peritoneum is 
raised hy hooks. (Testut.) 
The Urethra. 
The urethra is the tube by which the urine is conducted from the bladder. Its 
name, like “ ureter,” is derived from the Greek word which means “ to urinate.” 
The male and female urethrae differ so materially that a separate description of 
each is necessary. 788 
THE UJRINABY SYSTEM. 
The Female Urethra. 
This tube (Fig, 857) begins at the meatus urinarius interims in the bladder, 
and ends at the meatus urinarius extern us in the vulva. It runs downward and 
DORSAL VEirC 
OF CLITORIS - 
PREPUCE OF- 
CLITORIS 
GLANS CLI - " 
TORIDIS 
MEATUS^ 
a little forward, curving with the concavity in front. It is about one inch and a 
half long, and its lumen is about a quarter inch across. It is situated directly in 
front of, and is closely associated with, the lower part of the anterior wall of the 
vagina, through which it can be easily felt. Its external orifice is the narrowest 
part, and is located between the clitoris and the opening of the vagina. The front 
and rear surfaces of the tube are in contact. 
The lining is a pale mucous membrane, and it is gathered into small, longi- 
tudinal folds (Fig. 858). Its epithelium is flattened and stratified, except at the 
uppermost part, where it is transi- 
tional ; its corium is beset with 
small papillae, which are most nu- 
merous near the lower end. Mu- 
cous glands are abundant. The 
submucous coat is areolar, and 
contains an unusual proportion of 
yellow fibrous tissue. Outside of 
this is the muscular tunic in two 
layers, an internal longitudinal, 
and an external circular. At the 
vesical end of the tube the circular 
fasciculi are particularly numer- 
ous, and form a ring, which is 
erroneously called the sphincter 
of the bladder, but is properly 
named the internal sphincter of the 
urethra. Between the muscular 
layers are scattered many elastic 
fibres. In both layers, and es- 
pecially in the longitudinal, is a 
great quantity of blood-vessels, the veins being far more conspicuous by their 
number and size, and in their arrangement highly suggestive of erectile tissue, 
Fig. 857.—The female urethra and surrounding parts seen in sagittal section. (Testut.) 
LONGITUDINAL 
, MUSCLE 
CI RCU LAR 
M USC LE 
—VEIN 
MUCOSA 
Fig. 858.—The female urethra, seen in coronal section. 
(Testut.) THE URETHRA. 
789 
though unlike this in being disseminated throughout the muscular coat, instead 
of constituting a discrete layer. 
The female urethra is very distensible, and may be dilated far beyond its 
usual calibre without loss of its tone. 
The male urethra (Fig. 859) is a tube which carries not only urine, but also 
semen, and only a small portion nearest the bladder is devoted exclusively to the 
former use. It extends from the meatus urinarius interims in the bladder to the 
The Male Urethra. 
PROSTATIC 
f URETHRA 
[MEMBRANOUS 
URETHRA 
SPONGY URETHRA 
meatus urinarius externus at the distal end of the penis. It is divided into three 
portions : first, the prostatic (called also the prostatic urethra), named from its 
being contained in the prostate gland; second, the membranous (called also the 
membranous urethra), reaching from the distal end of the prostate to the proximal 
end of the spongy body, and passing through the triangular ligament of the 
perineum, named because, instead of being embedded in the substance of some 
organ, as are the other portions, it is a free tube in the greater part of its extent; 
and third, the spongy portion or the spongy urethra, which occupies the corpus 
spongiosum of the penis. 
The length of the urethra varies at different times in the same individual, 
owing mainly to physiological changes in the condition of the erectile penis, in 
which the largest part of the urethra is contained. In the flaccid state it measures 
inches ; but this length is vastly increased by the erection of the penis. In the 
common operation of catheterization the urethra is stretched two inches or more. 
Its length is divided among its three portions as follows : prostatic inch, mem- 
branous f inch, spongy 4| inches. The first and second parts are not subject to 
great physiological changes such as characterize the third. 
The urethra has two pronounced curves. In the prostatic portion its course is 
nearly perpendicularly downward ; in the membranous it runs downward with a 
forward sweep ; in the spongy it passes forward almost horizontally for two inches, 
and then bends sharply downward. Thus, the first and second portions describe 
Fig. 859.—The male urethra, in sagittal section. (Testut.) 790 
THE URINARY SYSTEM. 
a gentle curve which is concave forward, and the third portion has a curve (so 
sharp as to be almost an angle) about midway of its length (Fig. 860). This 
second curve is obliterated when the body of the penis is raised, as in the intro- 
duction of an instrument to the bladder through the urethra, and also during 
erection. The part of the urethra between this curve and the bladder is called 
MUSCULAR WALL 
OF BLADDER 
-UTERUS MASCULINUS 
LONGITUDINAL MUS 
CLES OF URETHRA 
Fig. 860.—Proximal portions of urethra with surrounding parts. (After Testut.) 
the fixed portion ; but it is practicable for a skilled hand to pass a straight instru- 
ment into the bladder without injuring the tube or its surroundings. 
The bore of the urethra varies in size and shape in different parts (Fig. 861). 
The prostatic portion has the largest calibre, measuring one-third of an inch half 
way of its course, and a little less at its extremities. It is also the most dis- 
tensible segment. In its hind surface (the floor) is an elevation which rises 
gradually from behind and then descends more abruptly (Fig. 862). This is 
called by various names—verumontanurn, “ a mountain spit,” caput gallinaginis, 
“the cock’s head,” colliculus seminalis, “ the little seminal hill.” From the sum- 
mit of this ridge a little tubular cavity runs upward and backward for about half 
an inch, called uterus masculinus, “ the male womb,” because it is the homologue 
of the uterus of the female. It is also called sinus pocularis, “ the cuplike hol- 
low,” and vesicula prostatica, “ the prostatic vesicle.” Upon its lateral lips open 
the two ejaculatory duets, through which the semen is squirted into the urethra. 
On each side of this mound is a groove, the prostatic sinus, into which open the 
most and the largest of the ducts from the glandular masses of the prostate, the 
smaller ducts opening in the sides and roof (front surface) of the tube. The 
presence of the crest causes a transverse section of the urethra to look like an 
inverted U. The membranous portion has a diameter of one-fifth inch or less, 
which is also that of the meatus externus. The latter is the least dilatable part, 
and, consequently, an instrument which will pass the meatus will go through 
every other portion of the canal. Where the membranous urethra perforates the 
rigid triangular ligament it is not as readily dilated as elsewhere. The spongy 
urethra has a calibre between the other portions in size, and uniform except at its 
extremities. In front for about half an inch it is dilated and thus forms the 
fossa navicularis, “ the boat-shaped pit,” and behind for nearly an inch it widens 
in every direction, making the pars bulbosa, “ the bulbous part.” 
The lowest point of the membranous urethra is about one inch beneath the 
pubic arch. The upper part of this portion is in close relation to the rectum. THE URETHRA. 
791 
Structure of the Urethra.—The inner coat of the urethra is mucous membrane, 
continuous above with that of the bladder, below with the skin. It is unusually 
rich in elastic fibres. It has, most markedly in the spongy portion, fine longi- 
tudinal folds, which are effaced during urination. The tube does not stand open, 
like the trachea or a severed artery, but opposite surfaces (generally the front and 
rear) of mucosa are in contact. The epithelium of the prostatic portion is 
similar to the vesical; in most other parts it is a simple columnar, but for a 
VERUMON. 
TANUM 
I M EM BRANOUS 
1 PORTION 
COWPER’S 
GLAND. 
Fig. BGl.—Cross sections of the male urethra at va- 
rious distances from its free end, showing marked al- 
terations of form. (Testut.) 
Fig. 862,—The male urethra, laid open on its 
anterior (upper) surface. (Testut.) 
WEATUS 
quarter inch back from the meatus it is of the flattened variety and stratified. 
The corium is plentifully studded with small papillae. Mucous follicles and race- 
mose glands are practically everywhere proximal to the navicular fossa. There 
are also many openings which were formerly thought to belong to glandular 
structures, but have been ascertained to be blind depressions obliquely set in the 
mucosa, their mouths always directed toward the external meatus (Fig. 863). 
They are lacunae, “little lakes,” and are found in the free spongy portion, proxi- 
mal to the fossa navicularis, in two sets, large and small. The large are one- 
third inch deep and occur in a single, median row in the anterior (upper) wall; 
the small are located principally in the anterior surface and at the sides in 792 
THE URINARY SYSTEM. 
longitudinal rows. Half an inch or more from the meatus externus in the ante- 
rior surface is a very large depression, nearly covered by a valve-like fold and, 
PROBE IN 
MAGNA 
IW GLANS 
called lacuna magna, “ the great 
lacuna.” In any of the larger 
pits the point of a fine instru- 
ment may catch, with results 
diagnostically misleading and 
therapeutically injurious. 
Doubtless, also, the obstinacy 
of gonorrhoeal inflammation is 
often due to the concealment 
of the specific virus in some of 
these recesses, beyond the reach 
of topical remedies. It will be 
seen that there are many open- 
ings upon the surface of the 
membrane—those of mucous 
follicles, racemose glands, pros- 
tatic glands, ejaculatory ducts, 
the uterus masculinus, and the 
lacunae ; to which array must be 
added the mouths of the ducts 
RIGHT LIP OF MEATUS- 
PREPUCE RETRACTED' 
-SKIN 
UPPER WALL OF URETHRA 
LATERAL LACUN/E 
-SIDE OF URETHRA 
SPONGY BODY Cllt SUlfaCft— 
•LARGE LACUNA 
spongy body—cut surface 
MEDIAN LACUN/E 
Fig. 863.—The distal portion of the male urethra, laid open 
on its posterior (under) surface, showing the lacunae. (Testut.) 
CORPUS 
SPONGIOSUM 
of Cowper’s glands, in the proximal part of the spongy urethra, the glands them- 
selves being situated one on each side between the two layers of the triangular 
ligament, close to the membranous portion of the tube. 
The mucous membrane is surrounded by an areolar coat of great elasticity, in 
the meshes of which are large numbers of convoluted vessels, mostly venous, a 
tissue similar to the true erectile tissues being thus constituted. Outside of this is 
a coat of unstriped muscle in two layers, the inner being longitudinal in the dis- 
position of its fasciculi, the outer circular. The whole is enclosed in a fibrous 
tunic of variable thickness. In the upper part of the prostatic portion the circu- 
lar muscular layer is thick, and is sometimes spoken of as the sphincter of the 
bladder ; but it should be called the internal sphincter of the urethra. This should 
not be confounded with the structure of striped muscle which surrounds the 
membranous portion above the triangular ligament, and is the external sphincter 
of the urethra. The compressor urethrae embraces the membranous portion in the 
space between the two layers of this ligament. THE DUCTLESS GLANDS 
F. H. GERRISH. 
THERE are several organs whose general, gross appearance is very similar to 
that of secreting glands, but which are conspicuously unlike the latter in 
the respect that they do not possess any duct by which their secretion is dis- 
charged. From this fact they have long been called ductless glands. This name 
involves a seeming paradox, for the word “ gland ” implies the capacity to form 
a product known as a secretion, and not only had nobody seen a secretion from 
one of these organs, but the absence of a channel of exit strengthened the idea 
that there was no such material to be discharged. With this view of the case 
authors endeavored to devise a name for this class of bodies, which should be 
more in accordance with the supposed facts. No such name, however, obtained 
general adoption, and the old title continued to be commonly employed, though 
with a mental protest by those who disliked inaccurate nomenclature. 
In recent years investigations along physiological and pathological lines have 
shown that some of these organs have a profound influence upon nutritive changes 
in the body, and have established the fact of “ internal secretion,” In other 
words some of these bodies have been found to form substances out of materials 
brought to them in the circulation, and to discharge these products of their 
activity into the blood; and it is rendered highly probable that the others of the 
group have a similar office. Since the fact of internal secretion is so well estab- 
lished, it is unnecessary longer to seek for another name for this class of organs, 
which, though ductless, are really glands. 
These glands are the spleen, the thyroid body, the thymus, the suprarenal 
capsules, the hypophysis, the parathyroids, and the carotid and coccygeal glands. 
Some writers include the tonsils and the epiphysis in the enumeration ; but the 
former are more properly counted among the lymphatic structures, and the latter 
probably has no appreciable use, being an aborted attempt at the formation of a 
third eye. 
It is not inappropriate to remark in this connection that the possession of a 
secretion and an excretory duct for it does not necessarily prevent an organ’s 
having an additional function of like nature with that of the ductless glands. 
For example, the liver has other duties besides that of secreting the bile; and 
the testicles, while forming the essential elements of the semen, exert a profound 
impression upon the physical and mental attributes of the individual, as best 
shown in the arrest of development in various directions in those persons who 
have been castrated before reaching the age of puberty. 
THE SPLEEN. 
The spleen (lien) (Fig. 864) is the largest of the ductless glands. It is situ- 
ated in the dorsal part of the epigastric and left hypochondriac regions, behind 
793 794 
THE DUCTLESS GLANDS. 
the stomach, covering the distance from the eighth to the eleventh ribs, and lying 
with its long axis in line with that of the tenth rib. Its measurements are usually 
not less than five inches for length, three 
for breadth, and one inch for thickness, 
and they may be considerably more than 
the above without departure from the 
normal, so great are the variations of its 
size within physiologic limits. Its weight 
also differs, conformably with its size, but 
will generally be five ounces or more. It 
is purple in color, of a soft consistency, 
rather friable, and sags out of shape by 
its own weight. 
Surfaces and Borders.—lt presents three 
distinct surfaces, separated by three bor- 
ders. The phrenic surface, so called from 
its relation to the diaphragm, is convex, 
is as large as both of the others, and faces 
backward and to the left. The opposite 
(mesial) area is divided by a lengthwise 
ridge into a larger, anterior, concave gas- 
tric surface, in contact with the stomach, 
and a smaller, posterior, concave renal 
surface, which receives the left kidney. 
The lower end is blunt, and is sometimes 
designated as the basal surface. The 
anterior border is between the phrenic and 
gastric surfaces, is sharp and notched; 
Fig. 864.—The spleen, showing the gastric and 
renal surfaces and the blood-vessels. (Testut.) 
the posterior horder separates the phrenic and renal surfaces, and is rounded; the 
interned border is the ridge between the gastric and renal surfaces. Upon the 
gastric surface, close to the internal border is a notch, the hilum, marking the 
passage of the splenic vessels and nerves. 
Structure of the Spleen. 
The spleen has a complete serous coat (Fig. 865), which is reflected from it 
at the hilum, a layer passing to the stomach, as the front lamina of the gastro- 
splenic omentum, the hind lamina being contributed by the small sac of the 
peritoneum, and another layer passing to the kidney, as the hind lamina of the 
lieno-renal ligament, whose front lamina is furnished by the small sac of the 
peritoneum. From the upper end of the spleen a serous fold, the phreno-splenie 
ligament, connects it with the diaphragm. 
Beneath the serous coat is the tunica propria, composed of mingled white 
and yellow fibrous tissues, the latter material being very abundant, and giving 
the organ great elasticity. Many cords and bands (trabeculce) project into the 
organ from the inner surface of this tunic, and some plain muscle-cells are 
mixed with the fibrous elements. At the hilum the tunica propria is reflected 
inward upon the vessels, and forms sheaths around them. At some distance 
from the surface, the arteries having become smaller by branching, the character 
of the sheath is changed from fibrous material to lymphoid, and at frequent 
intervals it is thickened so as to present globular or ovoid masses, the Malpighian 
corpuscles, sometimes inch in diameter. 
By the entrance of the trabeculae in one direction and the ensheathed vessels 
in another, the contained room of the spleen is divided into numberless, minute, 
irregular, intercommunicating spaces ; and these last are subdivided by delicate 
fibrous strands, connecting trabeculae and vessel-sheaths, the surfaces of these 
little cords being covered by branched fibrous-tissue cells. The resulting areolae THE SPLEEN. 
795 
are occupied by the spleen-pulp, which is substantially blood, thickened by the 
addition of great numbers of leucocytes, among which are certain large cor- 
puscles, called splenic cells. 
The arrangement of the blood-vessels is extraordinary, and altogether peculiar 
to this organ. The splenic artery, which, judged by the standard of the arteries 
of other organs, is relatively very large, runs in the lieno-renal ligament, and 
divides into five or six branches before entering the organ. Rapidly breaking 
Fig. 865.—Horizontal section in the region of the spleen. (Testut.) 
up into smaller vessels, when the minute arteriole stage is reached, which is 
generally succeeded by the stage of capillaries, the vessels abruptly terminate, 
and the blood is poured into the wall-less spaces of the spleen-pulp, from which 
it is collected by venules. The Malpighian corpuscles are factories for leucocytes, 
and the arterial blood courses among the latter, its flow being impeded by their 
great number and by the filamentous framework of the pulp-spaces. The blood 
in the splenic vein is remarkably rich in leucocytes. It is thought that one func- 
tion of the spleen is the disintegration of worn-out colored corpuscles of the 
blood, as the pulp contains many fragments of these cells. 
The lymphatics run in the tunica propria, the trabeculae, and the walls 
and sheaths of the vessels. They discharge into the splenic nodes, from which 
the lymph passes to the coeliac nodes. The nerves are derived from the solar 
plexus. 
The structure of the spleen is in some respects very similar to that of the 
lymph-nodes. The adenoid reticular tissue, the accumulations of lymph-cells, 
the great relative size in children, the atrophy which occurs in old age—all 
suggest an immense community of lymph-nodes, especially modified by a peculiar 
blood-supply. 
Not very infrequently accessory spleens (lienculi) are found. They are globular 
and small, but otherwise look like the principal spleen, near which they are 
situated. 796 
THE DUCTLESS GLANDS. 
THE THYROID BODY. 
The thyroid body (gland,ula thyroided) (Fig. 866) has, independently of its 
function of internal secretion, a claim to the name of gland, because it began its 
PYRAMID OF 
THYROID BODY 
RIGHT LOBE OF, 
THYROID BODY 
Fig. 866.—The thyroid body and the related blood-vessels. (Testut.) 
career as a secreting organ with a duct. In the description of the tongue 
mention was made of the foramen csecnm, just at the rear of the hindmost 
circumvallate papilla. This blind hole is a remnant of the thyro-glossal duct, the 
channel through which the thyroid (in the early foetal condition a compound 
tubular gland) communicated with the pharynx. In the process of development 
the duct became shrunken, and finally was nearly obliterated. The acini of the 
gland, having thenceforth no excretory duct, become dilated with their secretion, 
which is introduced into the system doubtless through the lymphatics, perhaps 
also by the veins. 
The thyroid gland is commonly described in connection with the organs of 
respiration ; but this association is not justified by likeness of structure or simi- 
larity of function, and rests merely upon the circumstance of contiguity. 
The thyroid consists of twTo lettered lobes, usually connected at their lower 
parts by an isthmus. The gland extends vertically from the fifth or sixth tracheal 
ring to the side of the thyroid cartilage, and backward to the side of the pharynx 
and gullet. When present, the isthmus generally lies across the second, third, 
and fourth rings. The lobes are broadest below and taper to a point above. They 
are superficially convex, and adapted to the form of the structures against which 
they lie. Each is about two inches long, one and a fourth inch wide at its broad- 
est part, and three-fourths of an inch thick; but these figures are subject to great 
variations in different cases. During menstruation the thyroid of the female is 
somewhat increased in size. In infancy it is relatively larger than in the adult. 
The lobes are attached by fibrous tissue to the larynx and trachea, wherever in 
contact with these organs; and distinct lateral ligaments bind them to the cricoid 
and uppermost part of the windpipe. THE THYMUS. 
797 
Frequently a slender, tapering process, called the pyramid (pyramidal process, 
middle lobe), runs upward to the hyoid between the lateral lobes, from one of 
which (usually the left) or from the isthmus it arises. This is a part of the 
remains of the thyro-glossal duct, mentioned above. The gland is commonly of 
a dark red color, and its weight is an ounce or more. 
The thyroid body has a strong tunic of fibrous tissue, from the inner surface 
of which trabeculae are given off, incompletely dividing the parenchyma into 
irregular lobules. These lobules are composed of closed vesicles, which are the 
original, tubular acini of the gland, matured and altered by reason of the closure 
of their excretory ducts. The vesicles are of many shapes and various sizes, the 
largest not exceeding one twenty-fifth inch in diameter. They are lined with a 
single layer of short, columnar epithelial cells, and filled with a colloid fluid. 
They are held together by areolar tissue, in which course the vessels and nerves. 
The arteries of the gland are the superior thyroids, inferior thyroids, and 
occasionally the thyroidea ima. These vessels are of large size relatively to the 
volume of the gland, and make abundant anastomoses. The capillaries form a 
close plexus around the vesicles, and even penetrate between their epithelial cells. 
The veins are arranged in an intricate network on the surface of the gland, from 
which the blood is collected by the superior, middle, and inferior thyroid veins. 
The lymphatics begin in spaces about the vesicles, form a plexus in the capsule of 
the gland, and empty into the deep cervical nodes. Colloid matter, like that in 
the cavity of the vesicles, is found in the lymphatics. The nerve-supply is rather 
scanty, and is derived from the middle and inferior cervical ganglia of the 
sympathetic. 
Accessory thyroid glands of small size are occasionally found in this region. 
THE THYMUS. 
The thymus (Fig. 867) is a temporary organ, growing somewhat rapidly until 
it attains a considerable size, and then gradually dwindling until it is merely 
vestigial. 
It is situated in the anterior mediastinum and lower part of the neck, between 
Fig. 867.—The thymus, the sternum and costal cartilages having been removed. (Testut.) 
the lungs, in front of the heart, the great vessels, and trachea, and reaching 
upward nearly to the thyroid. It appears at the end of the second month of 798 
THE DUCTLESS GLANDS. 
intrauterine life. At birth it measures two inches vertically, and half an inch 
ventro-dorsally and laterally ; and it weighs a drachm and a quarter. It is 
largest when the child is two or three years old, and its weight at that time is six 
drachms. Thereafter it slowly and steadily atrophies, and has nearly disappeared 
by the fifteenth year, although traces of it may be discovered in old age. 
It has a rosy hue in the foetus, is grayish-pink in the infant, and later becomes 
yellowish. It is soft and compressible, and sags out of shape by its own weight. 
It is vertically elongated, and is largest below. 
It has two lobes, approximately symmetrical—the right lateral and the left 
lateral—perfectly independent of one another. Each lobe has a delicate fibrous 
envelop, from whose visceral surface partitions extend inward, dividing the lobe 
into a large number of irregular, polyhedral lobules. If the envelop is cut 
between the lobules, the whole lobe can be unfolded, and the lobules are then found 
to be arranged around a central cord, close to which they are continuous with each 
other, but at the periphery of the lobe are free. 
A lobule consists of clusters of little nodules, which are essentially lymphatic 
in character. Each nodule has a cortical and a medullary portion, the lymph- 
cells being more numerous in the former, and the latter containing peculiar cells 
(of Hassall) in nests, the large containing smaller. These medullary corpuscles 
are the representatives of the epithelium of which the thymus originally was 
largely composed, before the invasion of lymphatic tissue. A capillary network 
surrounds the nodule. 
As the gland shrinks away the interstitial, connective tissue increases, and 
multitudes of fat-cells are formed, the last fact accounting for the yellow tinge 
of the organ during this stage. 
The arteries of the thymus are derived from the internal mammary, the 
thyroids, the subclavian, and the carotid. The veins run to the left brachio- 
cephalic. The lymphatics empty into the superior mediastinal nodes. The 
nerves come from the pneumogastric and the sympathetic. 
THE SUPRARENAL CAPSULES. 
Suprarenal bodies, adrenals, glandules supra,renales—these are the most com- 
mon of the names given to the two organs, each of which surmounts a kidney, 
presenting an appearance suggestive of a liberty-cap, rakishly worn (Fig. 868). 
They are usually classed among the ductless glands, as is done here; but by 
some they are grouped with the organs of the central nervous system, on account 
of the prominence of their nerve-tissue, both fibrous and cellular. It is fairly 
well determined that they are essential to life, inasmuch as their complete removal 
is speedily followed by death, as also is their entire degeneration in disease. 
Their precise function is still unknown. 
The suprarenal capsules are situated in the epigastric region, resting upon the 
top, and the inner and front surfaces of the kidneys, to which organs they are 
attached by areolar tissue. They are separated by the vertebral column, the 
distance between them being about two and a half inches. Their size is variable ; 
but the length rarely exceeds two inches, the width one inch and a fourth, and 
the thickness one-fourth inch. Each weighs about a drachm. The left is a little 
larger than the rigid. At birth they have nearly attained their adult size. On 
the anterior surface is a groove, running nearly crosswise, called the hilum. 
The right suprarenal body is pyramidal. Its anterior surface is nearly covered 
by peritoneum. It is adherent to the liver in an impression on the under sur- 
face of that gland, at the right of the vena cava. 
The left suprarenal body is not as tall as the right, but extends farther down- 
ward on the vertebral border of the kidney. It is in contact with the spleen, 
stomach, and pancreas. The upper part of its anterior surface is clothed with 
peritoneum of the small sac. THE SUPRARENAL CAPSULES. 
799 
Structure.—Section of a suprarenal body (Fig. 869) shows it to be composed 
of a peripheral portion, the cortex, and a central portion, the medulla—the two 
being separated by loose, areolar tissue, and the whole mass enclosed in a thin, 
fibrous capsule, which sends inward numerous vertical trabeculae, between which 
are many connecting bands. Mingled with the fibrous tissue is smooth muscular 
tissue. Thus are formed spaces in which are lodged the active cells of the organ. 
In the cortex, which is of a deep yellow color, the cells, granular, nucleated, 
polyhedral, are for the most part arranged in columns, perpendicular to the sur- 
face. 
The medulla is pulpy and dark brown, its color being principally caused by 
the great abundance of the blood-vessels of the part. The vessels are veins, 
arranged in a plexus in the fibro-muscular framework, and closely related to 
groups of large, irregular cells. 
The arteries, derived from the renal, and the phrenic, as well as directly from 
the aorta, enter at various points of the surface, and run inward in the trabeculae, 
SUPERIOR SUPRA- 
RENAL ARTERY 
ISUPRARENAL 
VEIN 
MIDDLE SUPRA- 
RENAL ARTERY 
■INFERIOR SUPRA 
RENAL ARTERY 
-RENAL ARTERY 
RENAL VEIN 
URETER 
Fig. 868.—Right suprarenal capsule and kidney, 
viewed from in front. (Testut.) 
Fig. 869.—Sagittal section of the right 
suprarenal capsule. (Testut.) 
giving off capillaries to the columns and other clusters of cells. The veins are 
nearly all gathered into the medulla, and their efferents are the radicles of a 
single vessel, which emerges at the hilum, and passes on the right side to the 
adjacent vena cava, on the left to the corresponding renal. The lymphatics 
begin in lymph-paths between the groups of cells and the framework, and run 
to the median lumbar nodes. 
The nerves are derived from the solar and renal plexuses. They are very 
numerous, and present many ganglia before entering the organ, and ganglion- 
cells in the medulla. 
The suprarenal capsules, like the kidneys upon which they rest, are surrounded 
by a quantity of adipose tissue. Quite often small accessory bodies of identical 
structure are found in the immediate neighborhood. 
Embedded in the surface of each lateral lobe of the thyroid body are two 
little masses, each about one-quarter of an inch in diameter, one on the inner and 
The Parathyroids. 800 
THE DUCTLESS GLANDS. 
one on the outer aspect. They are called the parathyroids {glandules, parathy- 
roidece). They are not like the thyroid in structure, being solid accumulations 
of epithelioid cells, among which run many blood-vessels. Various theories 
concerning their function have been advanced, but we are still ignorant of their 
service. 
The two glanduke caroticce are thus named because each is situated in the 
bifurcation of a common carotid artery. They are composed of nodules, each of 
which is a mass of epithelioid cells, among which are large capillaries. A fibrous 
capsule covers the gland and sends trabeculae between the nodules. 
The Carotid Glands. 
The glandula coccygea, is situated in front of the tip of the coccyx. It is 
about one-tenth of an inch in diameter, and is very similar in structure to the 
carotid glands. 
The hypophysis has already been described. 
The Coccygeal Gland. THE ORGANS OF GENERATION 
G. D. STEWART. 
THE MALE ORGANS OF GENERATION. 
THE reproductive organs of the male may be divided into essential and acces- 
sory. The former are the testicles, two glandular organs, which produce the 
spermatozoa. The accessory organs are (1) a long canal from each testicle, by 
means of which the spermatozoa are conveyed into the vagina of the female. This 
canal is divided into the vas deferens, the ejaculatory duct, and the urethra—the 
last being single and also belonging to the urinary system. (2) The seminal 
vesicles, reservoirs of the semen ; (3) the 'prostate gland, which adds an element to 
the semen as it passes outward; (4) the bulbo-urethral glands (Cowper’s), which 
also contribute to the volume of the semen ; (5) the scrotum, a pouch, consisting 
of a series of concentric layers, which envelop the testicles; and (6) the penis, 
the organ of copulation, which encloses the extrapelvic portion of the urethra, 
and which, when erect, effects the discharge of the semen into the vagina. 
THE TESTICLES. 
The testicles (“little witnesses” to masculinity), or testes (Figs. 870, 871), 
are two glandular organs which produce the spermatozoa, the principal element 
of the seminal fluid. They are suspended from the inguinal region by the sper- 
matic cords, and are surrounded and further supported by the scrotum. The 
left, as a rule, is a little lower than the right, and its spermatic cord is thus a 
little the longer. Each gland is from one and a half to two inches in length, one 
and one-quarter inch in width from before backward, a little less than an inch 
in thickness (measured transversely), and weighs from five to eight drachms. The 
consistence of the testicle is peculiar, varying somewhat according to the condi- 
tion of its seminiferous canals. When the latter are engorged it is firm; when 
they are empty, it is soft. 
Each gland is divided into two parts—the testicle proper and the epididymis. 
The latter must be regarded as the first segment of a canal through which the 
spermatozoa, after leaving the testicle, must pass to reach the urethra; but it 
is so intimately connected with the testicle that it may be described with that 
structure. 
The testicle proper is ovoid, flattened transversely, and presents two surfaces, 
two borders, and two extremities. The external surface is convex and turned 
outward and a little backward; the internal, almost flat, looks in the opposite 
direction. The anterior border is convex and turned slightly downward ; the 
posterior, almost straight, is directed upward and backward and has attached 
along its whole length the epididymis. The superior extremity is rounded, and 
occupies a plane a little external and anterior to the more pointed inferior ex- 
tremity. The latter gives origin to a fibro-muscular band, the scrotal ligament, 
which is attached by its distal end to the bottom of the scrotum, thus fixing the 
testicle to its envelops. 802 
THE ORGANS OF GENERATION. 
The Epididymis (“ upon the testicle ”) is a long narrow body, which lies 
along the posterior border of the testicle, encroaching somewhat on its outer 
surface. It is composed chiefly of the convolutions of a long canal (to be 
described later), and is divided into an upper extremity or head, a lower extremity 
or tail, and an intervening portion called the body. The head or globus major 
(“ greater globe”), the largest part of the epididymis, is round and smooth. It 
reposes like a hood on the upper extremity of the testicle, to which it is united 
by the tunica vaginalis, by an intervening layer of connective tissue, and by the 
vasa efferentia, which, on emerging from the testicle, immediately enter the globus 
major and make up the greater part of its bulk. The body iu horizontal section 
resembles a comma, and presents in consequence two surfaces and two borders. 
The anterior surface is concave, the posterior convex. Between the former and 
the testicle there is a short cul-de-sac, 
the digital fossa, which opens outward, 
and is lined by the tunica vaginalis. 
The internal border, corresponding to 
the tail of the comma, is thin, and 
floats in the cavity of the tunica 
vaginalis ; the external is thick, and 
lies immediately to the outer side of 
the vessels and nerves, as they enter 
the testicle. The tail or globus minor 
(“ smaller globe ”), intermediate in 
size between the body and head, is 
connected to the lower extremity of 
the testicle by a reflexion of the tunica 
vaginalis and by loose connective 
tissue. 
VAS DEFERENS 
JUNCTION OF 
PARIETAL 
AND VISCERAL 
LAYERS OF 
TUNICA VAQI- 
- NALIS 
-GLOBUS MAJOR 
Migration of the Testicle.—ln early 
foetal life the testicle is an abdominal 
organ lying below the kidney and be- 
hind the peritoneum. To its lower 
extremity there is attached a muscular 
band, called the gubernaculum testis 
(“ rudder of the testis ”), consisting 
of a central bundle of unstriped mus- 
cular fibers, which passes through the 
inguinal canal and is attached to the 
dartos at the bottom of the scrotum, 
and of lateral bundles of voluntary 
muscular tissue, which are derived 
UPPER END 
' OF TESTIS 
•HYDATID 
GLOBUS 
MINOR ‘ 
LOWER ENDi 
OF TESTIS 
Fig. 870.—Right testicle, its external surface. (Testut.) 
‘PARIETAL LAYER OF 
TUNICA VAGINALIS 
from the oblique muscles of the abdomen and are, therefore, attached below to 
the internal ring and the sides of the inguinal canal. Later the peritoneum sur- 
rounds the testicle and gubernaculum, forming a mesentery, the testicular portion 
of which is called the mesorchium (“ mesentery of the testicle ”). 
Soon there appears on the gubernaculum, at the internal ring, a pouch of peri- 
toneum, the processus vaginalis (“ sheathlike process ”), which elongates gradually 
and pushes through the inguinal canal into the scrotum, carrying in front of it 
the subperitoneal tissue, an infundibuliform process of the fascia transversalis, a 
few fibres of the internal oblique (which form the cremaster muscle), and the 
intercolumnar fascia. This pouch is then occupied by the testicle, which leaves 
its abdominal position about the third month of foetal life, reaches the internal 
ring about the sixth month, the external by the eighth, and shortly before birth 
descends into the scrotum. 
The cause of this descent is uncertain. That it may be due in small part to 
the progressive shortening of the gubernaculum is undeniable ; that it is in 
greater measure owing to the fact that the lumbar region grows away from the THE TESTICLES. 
803 
testicle, which is fixed by the gubernaculum, is probable. It must be noted too 
that the peritoneal pouch precedes the testicle, and, since the former is attached 
to a lower point in the gubernaculum, this fact may be explained in the same 
way. After descent has been completed, the remains of the central gubernacular 
VAS DEFERENS 
GLOBUS ( 
MAJOR ' j 
UPPER END, 
OF TESTISi 
HYDATIDJi 
HIND BORDER 
OF TESTIS 
Fig. 871.—Right testicle, its internal surface. (Testut.) 
band may be found in the scrotal ligament already described ; the lateral bands, 
having ceased to act after the testicle has reached the external ring, are drawn 
down, and may be found in the form of scattered bundles (the internal cremaster 
of Henle), lying amidst the other elements of the spermatic cord. 
The peritoneal sac which preceded the testicle is at first continuous with the 
general peritoneal cavity. Shortly before birth, however, the upper part of the 
tube of communication becomes closed, and this obliteration extends gradually 
downward to within a short distance of the testicle. That portion of the sac 
which surrounds the testicle is thereby completely cut off from the peritoneal 
cavity, and forms the tunica vaginalis. The obliterated portion of the pouch 
usually remains as a fibro-cellular thread, lying among the other elements of the 
cord. Sometimes this maybe traced as a distinct band from the peritoneum at the 
internal ring above to the tunica vaginalis below ; sometimes it is lost on the cord. 
Occasionally the tube of communication remains open, and then the abdominal 
viscera may pass into the tunica vaginalis, forming the congenital variety of 
hernia. In other cases the tube contracts, and forms a very minute canal, which 
may be traced downward a greater or less distance on the cord. A similar minute 
tube of peritoneum, observed in connection with the round ligament in the female, 
is called the canal of JVuek. 
One or both testicles may fail to reach the scrotum until shortly after birth, or 
their descent may be delayed until puberty; they may even remain permanently 
within the abdomen, or be arrested at any part of their course. 
The Tunica Vaginalis (“ sheathlike coat ”) is a closed serous sac, of peritoneal 
origin, which invests the testicles and lines the scrotum, and may, therefore, be 
divided into visceral and parietal portions. 804 
THE ORGANS OF GENERATION. 
The visceral layer is intimately adherent to the tunica albuginea of the testicle 
proper, except along the posterior border of the gland, where the epididymis is 
attached, and where the vessels and nerves enter or emerge. It also invests the 
globus major, lines the digital fossa, and covers the external border and posterior 
surface of the body of the epididymis, but leaves uncovered almost the whole of 
the globus minor. 
The parietal layer, of greater extent than the visceral, lines the infundib- 
uliform fascia, to which it is loosely attached by a prolongation of the sub- 
peritoneal tissue. It also covers the spermatic cord for a short distance above 
the testicle, extending somewhat higher on the inner than on the outer side. At 
the posterior border of the gland the two layers are, of course, continuous. 
The inner surface of the tunica vaginalis is lined by a layer of epithelial cells, 
and the membrane secretes enough fluid to moisten the apposed surfaces. 
Minute Structure of the Testicle.—Structurally the testicle consists of the fol- 
lowing parts : (1) a fibrous covering, the tunica albuginea, from which is derived 
a framework ; (2) the tubuli seminiferi ; (3) certain excretory canals ; (4) inter- 
stitial tissue. 
The Tunica Albuginea (“whitish coat”) is a dense, white, fibrous, inelastic 
capsule, about one-sixteenth of an inch in thickness. Its inner surface reposes 
on the parenchyma of the testicle ; its outer is covered by the visceral layer of 
the tunica vaginalis. Behind, where the tunica albuginea covers the posterior 
border of the testicle, it becomes immensely thickened forming a cone-shaped 
body, the corpus Highmorianum or mediastinum testis (“ standing in the middle of 
the testis”), which projects forward a varying distance into the mass of the gland. 
This body approaches a little nearer to the upper than to the lower extremity of 
the testicle, lies closer to the internal than to the external surface of that organ, 
and is tunnelled by the larger blood-vessels and a network of ducts, the rete 
(“ net”) testis. By its summit and lateral faces the mediastinum gives origin to a 
system of thin laminae and slender trabeculae, which radiate to become attached to 
the inner surface of the tunica albuginea, thus divid- 
ing tine testicle into a varying number (150 to 300) of 
small pyramidal spaces, called loculi (“little places”). 
In these cavities are lodged the seminiferous canals 
and the interstitial tissue. The visceral surface of 
the tunica albuginea and its trabeculae is covered by 
a network of minute blood-vessels, connected with 
the spermatic blood-vessels, and called the tunica 
vasculosa. 
H€AD 
MIDDLE. 
PIECE 
Histologically the tunica albuginea is composed 
of bundles of white fibrous tissue, which interlace in 
every direction, mingled with a small number of fine 
elastic fibres. 
AXIAL 
FILAMENT 
The Tubuli Seminiferi (“ seed-bearing tubules ”), 
or seminiferous canals, produce the spermatozoa (Fig, 
872), and hence form the essential structure of the 
testicle. They occupy the loculi, and are by the lat- 
ter divided into a corresponding number (150 to 300) 
of more or less distinct masses, called lobules. These, 
like their containing loculi, are pyramidal, their bases 
corresponding to the inner surface of the albuginea, 
their apices resting on the mediastinum. They each 
contain two or more seminiferous tubes, making of 
the latter from five to nine hundred for each testicle. 
TERMINAL 
SEGMENT 
Fig. 872.—Human spermatozoa. 
The right one is seen in profile, 
(Testut.) 
The tubes vary in diameter from to T|y of an inch, and are so flexuous 
that, when uncoiled, their length is increased twenty to thirty times (over two 
feet). They begin near the bases of the lobules by blind extremities. In their 
course toward the mediastinum they give off* two or three csecal diverticula, and THE TESTICLES. 
805 
exhibit frequent anastomoses, particularly near their origin, not only with the 
tubes of the lobule to which they belong, but with those of adjoining lobules. 
Near the mediastinum the canals of each lobnle unite to form a single straight 
excretory tube, one of the tubuli recti. 
The wall of a seminiferous tubule, on cross section, is seen to consist of several 
concentric layers of epithelial cells. The cells of the innermost layer are united 
edge to edge to form a basement membrane ; the outer layers are incomplete. 
Within the tubule are several layers of small epithelial nucleated cells, the pro- 
genitors of the spermatozoa. (See page 77.) 
The excretory canals (Fig. 873) of the testicle do not produce spermatozoa, 
but simply serve to convey the latter from the tubuli seminiferi to the canal of 
the epididymis. They are the tubuli recti, the rete testis, and the vasa elferentia. 
The tubuli recti, formed in the manner already indicated at the apices of the 
lobules, are short, straight, and of smaller calibre than the seminiferous canals 
from which they spring. They penetrate the mediastinum, and in its anterior 
EFFERENT 
CONES 1 
-VAS DEFERENS 
-EPIDIDYMIS 
LOBULE- 
-MEDIASTINUM 
WITH RETE 
TRABECULA- 
... TUNICA 
ALBUGINEA- 
-VAS ABERRANS 
Fig. 873.—Diagram of testicle proper and epididymis. (Testut.) 
portion break up into the rete testis. The walls of the straight tubules are made 
up of the fibrous tissue of the mediastinum, lined by a single layer of prismatic 
cells. The rete testis occupies the whole length of the mediastinum, and is com- 
posed of anastomosing vessels of irregular calibre, which vary in diameter, but are 
always larger than the seminiferous canals or the straight tubules. Like the lat- 
ter they have no proper wall but are simply channels dug out of the fibrous tissue 
of the mediastinum, and lined by an epithelium which is here cylindrical, there 
cubical, or even of the flattened variety. At the upper and back part of the tes- 
ticle these channels finally unite to form a smaller number of canals, the vasa effer- 
entia (“ vessels carrying from ”). The latter almost immediately escape from the 
albuginea, and enter the globus major, with which structure they will be described. 
The interstitial tissue is a very delicate connective tissue, which supports the 
seminal tubules and the smaller ramifications of the blood-vessels. It is derived 
from the trabeculae, and is peculiar in that it contains, besides the ordinary cells 
of connective tissue, the so-called interstitial cells. These are large, rounded or 
oval corpuscles, some of which exhibit branching processes. Their protoplasm is 
granular, often filled with fat, and may contain a brown or yellowish pigment. 
They occupy divers situations, surrounding the smaller vessels and lying between 
the tubules, and are either a special variety of connective-tissue cells, or are derived 
from cells of the germinal epithelium, which have not been utilized in forming the 
tubes. In the spaces of this tissue the lymphatics of the testicles take birth. 
Minute Structure of the Epididymis.—The vasa eferentia, ten to fifteen in 
number, carry the spermatozoa from the rete testis to the canal of the epididymis. 
Emerging from the testicle at its upper and back part, they are at first straight, 806 
THE ORGANS OF GENERATION. 
but soon become coiled and convoluted, forming a.series of cone-shaped masses, 
the com vasculosi. These cones, their apices turned toward the tunica albuginea, 
are each about one-third of an inch in length ; together they constitute the 
globus major. The tube of which each is composed is about one-thirtieth of an 
inch in diameter near its origin, about half as large at its termination, and 
measures when uncoiled from six to eight inches in length. The uppermost 
vessel merges without line of demarcation into the canal of the epididymis, the 
remainder open at regular intervals into that canal. The walls of the etferent 
vessels are made of smooth muscular fibres, circularly arranged, and lined by a 
ciliated, cylindrical epithelium. 
The canal of the epididymis takes origin in the globus major in the manner 
already described. Extending downward, it forms the body and globus minor, 
and then merges into the vas deferens. It is disposed in numerous coils, held 
together by areolar tissue. The length of the canal when uncoiled varies from 
twelve to twenty feet, and its diameter, about one-sixtieth of an inch above, 
gradually decreases as it approaches the globus minor, to enlarge again beyond 
that point. The walls are thin, and are composed of smooth muscular tissue, 
which near the vas may be separated into a superficial longitudinal layer and a 
circular one. This muscular coat is lined by a layer of ciliated, columnar 
epithelium. The cilia of the canal are longer than those found in the efferent 
vessels, but like the latter their motion is toward the vas. Beneath the fixed 
ends of the columnar cells is found a layer of young cells, destined later to 
replace the former. 
Vessels and Nerves.—The arterial supply of the testicle is derived chiefly 
from the spermatic artery, which joins the other structures of the spermatic cord 
at the internal ring. Approaching the gland it divides into two sets of branches 
—testicular and epididymal. The former, at the posterior superior portion of 
the testicle, subdivides into two sets of branches, as follows : (1) a peripheral 
group which travels forward in the thickness of the albuginea; (2) a central 
group, which pierces the mediastinum, and breaks up into a plexus on the walls 
of the loculi. From this a multitude of fine branches are sent to form plexuses 
around the walls of the seminiferous canals. The epididymal branches, joining 
with the terminal twigs of the deferential artery, form a plexus around the canal 
of the epididymis. 
The veins pierce the mediastinum, and unite into six or seven trunks, which 
form a plexus, the pampiniform (“ tendril-shaped ”), surrounding the spermatic 
artery, and lying in front of the vas. Farther up in the cord the veins become 
reduced to two or three, and these, following the artery into the abdominal 
cavity, finally unite to form a single trunk, the spermatic vein, which empties on 
the right into the inferior vena cava, on the left into the corresponding renal 
vein. The veins from the epididymis form a second group of two or three 
trunks only, which pass upward in the cord behind the vas, and empty into the 
deep epigastric veins. The lymphatics form a plexus around the seminiferous 
canals, where they begin as minute spaces lined by epithelial cells. Together 
with the lymphatics of the epididymis, they accompany the spermatic vessels to 
end in the lumbar nodes. The nerves are derived from the aortic, renal, and 
hypogastric plexuses of the sympathetic. Branches from these form a secondary 
plexus around the spermatic artery and the artery of the vas. Their mode of 
termination is not well understood. 
Foetal Remains.—The hydatids (“vesicles”) of Morgagni are two small bodies 
—one pediculated, the other sessile—which are found in connection with the 
globus major and the upper extremity of the testicle. The pediculated hydatid, 
rounded or pyriform in outline, and from one-eighth to one-third of an inch in 
length, is attached to the head of the epididymis, and covered by the tunica 
vaginalis. Its cavity, lined by a cylindrical, ciliated epithelium, contains a trans- 
parent fluid. This body is not always present, and its morphological significance 
has not been satisfactorily explained. The sessile hydatid, a rounded or flattened THE VAS DEFERENS. 
807 
projection of about the same size, is seated either on the front of the globus 
major, the upper extremity of the testicle, or between the two. It is nearly 
always present, is sometimes divided into several lobes, and contains in its centre 
a tubular cavity or canal, which either ends in blind extremities or becomes 
continuous with a seminiferous canal. Morphologically, this body represents the 
peritoneal end of the duct of Muller, and is, therefore, homologous with the 
fimbriated extremity of the Fallopian tube in the female. Sometimes, indeed, it 
may be found as an empty orifice with fringed borders. 
The organ of Giraldes or 'paradidymis (“beside the testicle”), a small, 
irregular, yellowish-white patch, which lies in front of the cord, immediately 
above the head of the epididymis and beneath the funicular portion of the tunica 
vaginalis, is made up of several small nodules, each containing a blind convoluted 
tube, lined with cylindrical, ciliated epithelium. It is a relic of the inferior 
portion of the Wolffian body. 
THE VAS DEFERENS 
The vas deferens (“vessel carrying away”) (Figs. 874, 875) is the prolonga- 
tion of the canal of the epididymis, and extends from the tail of the latter to the 
base of the prostate gland. 
It varies in length from six- 
teen to twenty inches, is cylin- 
drical in outline throughout 
the greater part of its course, 
and has an average diameter 
of about one-tenth of an inch. 
The vas travels upward in 
the spermatic cord, and may 
be divided into four portions 
as follows: (1) testicular; (2) 
funicular ; (3) inguinal; (4) 
abdomi no-pelvic. 
Direction and Relations.— 
The testicular portion, mark- 
edly tortuous, runs from its 
origin upward and a little 
forward, to about the middle 
of the testicle. It lies to the 
inner side of the epididymis 
and behind the testicle, and is 
separated from both by the 
spermatic vessels and nerves. 
The funicular portion is 
straight, and is continued 
vertically upward to the ex- 
ternal abdominal ring, lying 
behind the spermatic artery, 
nerves, and anterior group of veins, but in front of the posterior veins. The 
inguinal portion occupies the inguinal canal. The abdomino-pelvic division is, in 
the greater part of its course, retro-peritoneal. At the internal abdominal ring it 
leaves the spermatic vessels and turns inward, curving around the outer side of 
the deep epigastric artery. Crossing the external iliac vessels on their inner 
side, it then enters the pelvis close to the ilio-pubic suture, and curves downward 
and backward on the lateral wall of the bladder, crossing in this part of its 
course obliquely and to the vesical side of the obliterated hypogastric artery and 
the ureter. The terminal segment of this division, about two inches in length, 
runs forward between the bladder and the rectum. It is dilated, flattened from 
VAS DEFERENS'! 
UPPER LIMIT OF 
VESICULA BEFORE 
BEING UNRAVELED 
AMPULLA™ 
EJACULATORY 
DUCT 
Fig. 874.—Right seminal vesicle, unraveled and viewed from 
behind. (Testut.) 808 
THE ORGANS OF GENERATION. 
before backward, sacculated, resembles the seminal vesicle, and is called the 
ampulla of Henle. The anterior surface of the latter is directly applied to the 
bladder wall; the posterior is separated from the rectum for a short distance 
above by the recto-vesical pouch of the peritoneum, below this, by the recto- 
vesical fascia. The external border of the ampulla lies in contact with the inner 
border of the corresponding seminal vesicle. The ampullae of opposite sides are 
separated by a triangular space, the inter deferential triangle, the apex of which 
corresponds to the base of the prostate, and in the opening of which the bladder 
and rectum are in almost immediate contact, separated only by the recto-vesical 
fascia. Close to the base of the prostate the ampulla again becomes narrow and 
straight, and is joined on its outer side by the corresponding seminal vesicle, to 
form one of the common or ejaculatory ducts. 
Minute Anatomy.—The walls of the vas consist of three coats-—areolar, mus- 
cular, and mucous. The outer or areolar coat is composed of fibrous tissue, 
mixed with blood-vessels, nerves, and smooth muscular fibres, arranged parallel 
to the long axis of the canal. The muscular coat constitutes about four-fifths of 
the entire thickness of the wall, and gives to the vas a firm, resistant feel, by 
means of which it may easily be distinguished from the other elements of the 
cord. It is composed of smooth muscular fibres, arranged in three planes. In 
the superficial and deep planes the fibres are longitudinal, in the median, which 
is much the thickest, they are circular. The mucous coat is whitish, presents 
three or four longitudinal folds, which are effaced by distention, and is lined by 
cylindrical, non-ciliated epithelium. In the ampulla the walls are thinner, and 
the mucous membrane presents many folds, which, uniting at divers angles, give 
to this portion an areolar appearance, resembling the seminal vesicles. These 
areoke are lined by cubical epithelium. 
Vessels and Nerves.—The artery, a branch of the superior vesical, joins the 
vas near its origin, and accompanies it to the testicle, anastomosing in the latter 
with the spermatic artery. The veins empty into the vesico-prostatic plexus and 
the veins of the cord. The nerves come from the inferior hypogastric plexus. 
The vas aberrans (“ vessel wandering from ”) is a narrow tube which comes 
from the lower end of the canal of the 
epididymis, or from the beginning of 
the vas. Becoming convoluted into an 
irregular mass, it extends upward be- 
tween the structures mentioned for an 
inch or more, and ends in a ceecal 
extremity. The tube when uncoiled 
measures from one and a half to fifteen 
inches in length. It agrees in structure 
with the vas, and is a relic of the upper 
part of the Wolffian body. 
THE SEMINAL VESICLES. 
The seminal vesicles (Figs. 874, 
875) are two lobulated pouches, serving 
as reservoirs for the semen, to which they 
add a secretion of their own. They are 
placed one on either side, external to the 
ampullfe of the vasa deferentia, and 
between the bladder and the rectum. 
Each vesicle is pyramidal in form, with the broad end directed backward, meas- 
ures two inches in length, and about a half inch in breadth at its posterior and 
widest part, and presents two surfaces, two borders, and two extremities. 
The anterior surface is attached to the base of the bladder, overlapping, for 
a short distance above, the ureter. The posterior surface is convex and covered 
Fig. 875.—Base of the bladder, showing the semi- 
nal vesicles and the vasa deferentia. (Testnt.) THE SCROTUM. 
809 
above by the recto-vesical pouch of peritoneum, below this, by the recto-vesical 
fascia, which alone separates it from direct contact with the rectum. The poste- 
rior extremities or bases are widely separated; the anterior converge, become 
narrowed, and near the base of the prostate unite on their inner sides with the 
corresponding vasa deferentia to form the ejaculatory ducts. Along the inner 
margin of each vesicle there runs the ampulla of the corresponding vas. 
Each vesicle consists of a central tube, four to six inches in length, from 
which are given olf many blind diverticula, the whole being coiled into the form 
just described, and held thus by dense, fibrous tissue. In minute structure it 
closely resembles the vas. Like the latter it has an external fibrous coat derived 
from the recto-vesical fascia, and containing blood-vessels, lymphatics, and nerves. 
Its middle or muscular coat is thin, but it is arranged in superficial and deep 
longitudinal layers and a middle plane of circular fibres. The mucous membrane, 
areolar in structure, like that of the ampulla, is lined witli non-ciliated, cylin- 
drical epithelium, beneath which is a deeper layer of polyhedral cells. 
Over the posterior surfaces and extending between the two vesicles is found 
a certain amount of smooth muscular tissue, also some longitudinal fibres, con- 
tinuous with those of the bladder wall. 
THE EJACULATORY DUCTS. 
The ejaculatory ducts (Fig. 876), two in number, one right, the other left, 
are formed close to the base of the prostate by the union, at a very acute angle, 
of the ampulla of the vas and the corre- 
sponding seminal vesicle. They convey the 
seminal fluid from the vesicles and vasa 
deferentia into the urethra. From their 
origins the two ducts run downward and 
forward, converging as they descend. After 
a very short course they enter the prostate, 
and pass forward side by side between its 
middle and lateral lobes, opening finally 
into the prostatic urethra by two small ellip- 
tical orifices, placed one on either side of 
the sinus pocularis. Each duct is about 
three-quarters of an inch in length, and its 
lumen, diminishing from behind forward, is 
so small at the urethral end as barely to 
admit a very fine bristle. The walls of this 
tube are very thin ; the outer, areolar coat, 
found in the vas deferens and vesicula seminalis, has entirely disappeared; and 
the outer plane of longitudinal muscle-fibres becomes blended with the prostate. 
The muscular coat proper is therefore reduced to two layers, an outer of circular, 
an inner of longitudinal fibres. The mucous membrane resembles closely that 
found in the vas deferens. 
Arterial branches from the inferior vesical and middle hemorrhoidal supply 
the seminal vesicles and the extra-prostatic portion of the ejaculatory duct. The 
veins correspond, emptying into the vesico-prostatic plexus; the nerves are 
derived from the hypogastric plexus. The intra-prostatic portion of the ejac- 
ulatory duct receives its nutrient and nervous supply from the prostate. 
iAM PULLA 
SEMINAL 
“vesicle 
EJACULATORY 
DUCT 
URETH RA 
Fig. 876.—Ejaculatory duct in sagittal sec- 
tion. (Testut.) 
THE SCROTUM. 
The scrotum (Fig. 877) is a pouch, which contains the testicles and a part 
of each spermatic cord. It consists of several layers which are from without 
inward as follows : (1) the integument; (2) the dartos; (3) the intercolumnar 
fascia; (4) the cremasteric fascia; (5) the infundibuliform fascia; (6) the sub- 810 
THE ORGANS OF GENERATION. 
peritoneal tissue; (7) the parietal tunica vaginalis. The integument forms 
a common covering for both testicles; the remaining layers, meeting in the 
median line, form the septum scroti, which passes inward between the two glands, 
giving to each a separate compartment. 
The Integument is thin, very distensible, deeply pigmented, covered with 
v 
RIGHT INGUINAL CANAL‘S 
(opened) 
( PERSISTENT SEROUS 
< CAVITY AROUND 
(cord—EXCEPTIONAL 
CREMASTERIC MUSCLE- 
AND FASCIA 
lIMTERCOLUM NAR 
FASCIA 
TUNICA VAGINALIS— 
PARIETAL LAYER 
■INFUNDIBULIFORM 
FASCIA 
DARTOS 
RIGHT HALF OF SCROTUM SKIN 
LEFT HALF OF SCROTUM 
Fig. 877.—The scrotum. On the left side the cavity of the tunica vaginalis has been opened; on the right 
side only the layers superficial to the cremaster have been removed. (Testut.) 
short hairs, and studded with numerous sudoriparous and sebaceous glands. 
Along its median line there runs a longitudinal ridge or raphe, from which 
numerous folds are directed transversely outward. 
The Dartos (“flayed”) is a thin, reddish, fibrillated layer, which lines 
and is intimately attached to the deep surface of the integument. It corre- 
sponds to the two layers of the superficial fascia, with which it is continuous 
over the abdomen and groin ; but it differs from these in that it consists of 
elastic tissue, with abundant, smooth, muscular fibres, and contains no fat. The 
muscular fibres, mostly longitudinal in direction, are attached to the deep surface 
of the skin. Under the influence of cold, mental emotion, and in the healthy, 
they are contracted, causing the scrotum thereby to become short and corrugated ; 
in the feeble, and under the influence of warmth, they relax, and the scrotum 
becomes pendulous, and its ridges almost effaced. The dartos, as such, is con- 
tinued over the penis and perineum. 
The Intercolumnar Fascia (external spermatic) is a thin, fatless, transparent 
membrane, which lines the dartos. It is continuous above with the pillars 
of the external abdominal ring, and with the transverse fibres connecting 
them. THE SCROTUM. 
811 
The Cremasteric Fascia (-middle spermatic) consists of two layers of thin 
areolar tissue, between which are placed the voluntary muscular bundles—cre- 
master (“supporting”) muscle—derived from the internal oblique. At the 
bottom of the scrotum this layer blends with the dartos. 
The Infundibuliform Fascia (internal spermatic) is a delicate membrane derived 
from the fascia transversal is. It lines the cremasteric fascia. 
The Subperitoneal Tissue does not, properly speaking, form one of the layers of 
the scrotum. As a loose areolar structure continuous with the sub peritoneal tissue 
of the abdominal wall, it lines the infundibuliform fascia, investing and forming 
laminae between the different elements of the spermatic cord. Below, it connects 
loosely the inner surface of the infundibuliform fascia to the parietal layer of the 
tunica vaginalis. This with the preceding layer forms the so-called fascia propria. 
The tunica vaginalis has already been described. 
Vessels and Nerves.—The arterial supply of the scrotum comes from the 
superficial and deep external pndic, and from the superficial perineal, a 
branch of the internal pudic. The cremasteric artery, a branch of the deep 
Fig. 878.—Spermatic veins. (Testut.) 
epigastric, is distributed chiefly to the cremaster muscle; but it also sends 
branches to the deeper layers of the scrotum and anastomoses with the arte- 
ries of the testicle. The veins follow the corresponding arteries, and empty 
into the external saphenous and internal pudic. The lymphatics terminate in the 
superficial inguinal nodes. The nerves are from the ilio-inguinal, the two super- 
ficial perineal, the inferior pudendal, and the genital branch of the genito-crural. 
The latter is distributed chiefly to the cremaster muscle. 812 
THE ORGANS OF GENERATION. 
THE SPERMATIC CORD. 
The spermatic cord forms the pedicle of the testicle, and consists of the fol- 
lowing parts : (1) the vas deferens; (2) arteries ; (3) veins; (4) lymphatics ; (5) 
nerves ; (6) the processus vaginalis ; (7) the internal cremaster of Henle. These 
are cemented together by a loose areolar tissue, continuous with the subperitoneal 
fascia, and are surrounded by certain layers, continuous with those found in the 
scrotum. 
The vas deferens (page 807) forms the nucleus of the cord. The spermatic 
artery lies in front of, the deferential artery is placed behind, the vas. The veins 
from the testicle, six or seven in number, form the pampiniform plexus, which 
runs upward in front of and surrounding the spermatic artery. The veins from 
the epididymis form a group of two or three trunks only, which run upward behind 
the vas. The lymphatics accompany the veins. The nerves run with the arteries. 
The processus vaginalis may run to the testicle or be lost at any level of the cord. 
The internal cremaster of Henle, in the form of scattered bundles, is supposed to 
represent the lateral bands of the gubernaculum. 
The coverings are, from without inward, the skin, dartos or superficial fascia, 
intercolumnar fascia, cremasteric fascia, and infundibuliform fascia. At the level 
of the external ring the four outer coverings are lost. From this point the cord 
traverses the inguinal canal, and at the internal ring its elements diverge, the 
cord as such ceasing to exist. 
The penis (Figs. 879-886) is the male organ of copulation. It takes origin 
in the perineal region between the superficial perineal fascia and the inferior 
THE PENIS. 
PROSTATIC 
URETHRA 
MEMBRANOUS 
URETHRA 
SPONGY URETHRA 
Fig. 879.—The male urethra, in sagittal section. (Testut.) 
layer of the triangular ligament. Running upward and forward parallel with the 
ischio-pubic rami, it reaches a point above the scrotum and in front of the sym- 
physis, where it becomes free and surrounded by a cutaneous covering. It may 
be divided into an anterior expanded extremity or glans, a posterior perineal 
extremity or root, and an intervening portion, called the body. The first will be THE PENIS. 
813 
described with the corpus spongiosum from which it is derived ; the other divisions 
will be taken up separately after the minute anatomy of the organ has been 
considered. 
Structure.—The penis consists of three cylindrical masses of erectile tissue 
(two corpora cavernosa and a corpus spongiosum), and a system of envelops, 
which surround and hold these together. 
The Corpora Cavernosa, eacli about six inches long and half an inch in diameter, 
make up the greater part of the body of the penis. They are placed side by side 
and united along the anterior three-fourths of their extent, their contiguous sur- 
faces being somewhat flattened. Behind they diverge, and, becoming gradually 
narrower, terminate in pointed extremities, 
which are inserted, one on either side, into 
the middle of the ischio-pubic rami. The 
divergent portions, called the crura penis 
(Fig. 880), are fixed to the descending rami 
of the pubes by connective tissue, and in- 
vested by the ischio-cavernosi (erectores penis) 
muscles, which surround them more or less 
completely. In its course each crus presents 
a slight enlargement called the bulb. The 
distal extremities of the cavernous bodies, 
conical in outline, are received into corre- 
sponding depressions in the base of the glans, 
where they are firmly secured by fibrous tis- 
sue. Two longitudinal grooves, one dorsal, the 
other ventral, are formed by the union of these 
VERUMON^ 
TANUM 
COWPER’S 
GLAND 
MEM BRANOUS 
PORTION 
MEATUS 
Fig. 880.—The penis, proximal portion, seen 
from below. (Testut.) 
Fig. 881.—The male urethra, laid open on 
its anterior (upper) surface. (Testut.) 
bodies. The former lodges the deep dorsal vein, the latter, much the deeper, 
is occupied by the corpus spongiosum. 
Structurally each corpus cavernosum consists of erectile tissue, invested by a 
sheath, the tunica albuginea. The latter is composed of fibrous and elastic tissue, 
and is both tough and distensible. It is arranged in two layers, superficial and 
deep. The former, of longitudinal fibres, is common to both bodies; the latter, 
of circular fibres, is proper to each. In the median line, where the two bodies 
touch, these circular fibres blend, making a septum, dense and complete behind, 
but in its anterior portion interrupted by numerous vertical slits, and hence called 
the septum peetini for me (“ comb-shaped partition ”). From the inner surface of 814 
THE ORGANS OF GENERATION. 
the albuginea, numerous fibro-muscular lamellated or filamentous trabeculce are 
derived. These become smaller near the central axis of the body, and are stronger 
behind, in the vicinity of the crura, than in front. Crossing each other in divers 
directions, the trabecula! divide the cylindrical cavity of the albuginea into an 
immense number of spaces, called areolae,. The latter communicate freely with 
each other, and with those of the opposite body through the fissures in the sep- 
tum. They are lined by epithelial cells, resembling those found in the smallest 
arterial branches, and, therefore, represent widely dilated capillaries. At several 
points in their walls these spaces communicate with the arteries; they also give 
origin to the veins. 
The Corpus Spongiosum (Fig. 881) is traversed throughout its whole extent by 
the urethra. Its posterior extremity, somewhat dilated, is called the bulb, its 
anterior extremity, much dilated, makes up the glans, while the intervening por- 
tion is known as the body. 
The bulb (Fig. 880) is pear-shaped, about one and a half inches in length, and 
three-quarters of an inch in diameter at its widest part. It is larger than the 
body, and contains the bulbous portion of the urethra, which is here surrounded 
by a greater amount of erectile tissue than elsewhere. Its posterior extremity 
lies about half an inch in front of the anus. Tapering anteriorly, it soon gains 
the inferior groove, formed by the junction of the corpora cavernosa, and merges 
into the body. The superior surface of the bulb rests against the inferior layer 
of the triangular ligament from which it receives an investment ; its inferior 
surface is covered by the bulbo-cavernosi (acceleratores urinse) muscles. These 
muscles, two in number, arise from a median raphe on the under surface of 
the bulb. Diverging they encircle the latter and meet on its dorsal surface. A 
few of their most anterior fibres are sometimes inserted into the sides of the cor- 
pora cavernosa, or into the fascial sheath of the penis, in which case they com- 
press during erection the dorsal vein. The urethra does not occupy the central 
axis of the bulb, but lies nearer to its superior surface. 
The body is cylindrical or slightly tapering. It occupies the inferior groove 
formed by the junction of the cavernous bodies, and is tunnelled along its centre 
by the urethra. 
MEATUS 
DISTAL PART OF SEP- 
TUM PECTINIFORME" 
.FOSSA NAVIC 
U LARIS 
FRENUM 
GLANS. 
PENIS 
VALVE OF LA- 
CUNA MAGNA 
■LEFT SIDE OF URETHRA 
FLOOR OF URETHRA 
LACUNA MAGNA 
PREPUCE 
RETRACTED 
■>SKIN 
DORSAL 
VEIN 
CORPUS 
CAVERNOSUM 
CORPUS 
SPONGIOSU M 
Fig. 882.—The penis, distal end, in sagittal section one-twelfth inch at left of middle line. (Testut.) 
The glans (Figs. 882-884) forms the anterior extremity of the penis. It is 
conoidal in outline and presents at its summit a vertical fissure, the meatus urina- 
rius externus, the anterior opening of the urethra. Its base, directed backward, THE PENIS. 
815 
and hollowed to receive the tips of the cavernous bodies, as already mentioned, is 
not at right angles to the long axis of the penis, but so placed that it extends 
farther backward on the dorsal than on the ventral aspect of that organ. The 
prominent border of the base is called the corona glandis; the constricted portion 
of the body behind this, the cervix. The external surface of the glans is smooth, 
and presents below a longitudinal groove, which begins a little behind the meatus, 
extends backward, and lodges the frenum of the prepuce. 
Structure.—The corpus spongiosum is composed of a thin layer of erectile 
tissue, which surrounds the urethra and is enclosed in a fibrous sheath. It there- 
fore resembles the cavernous bodies; but the sheath is thinner and contains more 
elastic fibres, and the areolae are smaller. The erectile layer of the bulb is 
thickened and prolonged backward, so as to surround the membranous and pros- 
tatic portions of the urethra. The erectile structure of the glans is continuous 
with that of the spongy body, from which, however, it is derived only in small 
part, the greater portion being developed from the integumental tissues which 
invest the glans (Retterer). Its trabeculae are very coarse, its areolae small. 
During erection the corpus spongiosum never attains the same degree of rigidity 
as the cavernous bodies. 
The Envelops of the Penis, four in number, are concentrically arranged around 
the erectile cylinders. They are from without inward as follows : (1) the integu- 
ment; (2) the dartos ; (3) an areolar layer ; (4) the fascia of the penis. 
The cutaneous envelop (Figs. 882, 883, 886) is continuous with the integument of 
the pubic region and scrotum behind, and in front assists in forming the prepuce. 
It is thin, deeply pigmented, and free 
from fat; contains abundant elastic 
tissue ; and is remarkable for its dis- 
tensibility and the laxity of its 
attachment to the subjacent tissues. 
It is studded with sebaceous glands, 
and presents a median raphe on the 
under (hind) surface of the penis, 
continuous with that of the scrotum. 
The prepuce, or foreskin, is a 
tegumentary fold, disposed like a 
cuff around the glans. It is formed 
as follows: just behind the cervix 
the integument leaves the surface of 
the penis and is continued forward 
for a Varying distance, forming the 
outer layer of the prepuce; then it 
turns backward within itself, form- 
ing the inner layer, and rejoins the surface at the level ot the cervix. From 
this point the integument is reflected anew over the cervix and glans, to which it 
is intimately adherent, finally becoming continuous at the meatus with the mucous 
membrane of the urethra. Thus constituted, the prepuce presents two surfaces, 
outer and inner, and an anterior opening, the preputial orifice. Below, it is 
drawn forward in a median fold, the frenum, which occupies the ventral groove 
on the glans, and is attached a little behind the urinary meatus. The integu- 
ment, which forms the inner surface of the prepuce and covers the cervix and 
glans, is so modified in character as to resemble mucous membrane. Over the cervix 
and corona it is studded with numerous sebaceous follicles, the glandulce odoriferce, 
the secretion of which, added to the desquamated epithelial cells of this vicinity, 
forms a whitish substance of peculiar odor, the smegma prceputii (“ unguent of 
the foreskin ”). The integument over the glans adheres closely to the erectile 
tissue beneath, possesses only rudimentary sebaceous follicles, and is beset with 
large nervous and vascular papillae. 
The dartos layer is continuous with a similar structure in the scrotum, and is 
MEATUS 
-MEDIAN GROOVE 
FOSSA OF 
FRENUM 
.FRENUM 
CORONA 
NECK 
PREPUCE 
RETRACTEDJ 
Fig. 883—Glans penis, under surface. (Testut.) 816 
THE ORGANS OF GENERATION. 
formed chiefly of plain muscular fibres, the great majority of which are arranged 
longitudinally. It extends to the preputial orifice, then like the skin turning 
backward, it becomes more and more attenuated, and is finally lost on the cervix. 
When contracted, the dartos compresses the veins, and thus favors engorgement. 
The areolar sheath lying beneath the dartos, is prolonged forward as far as 
the preputial orifice. It is loose, rich in elastic fibres, but almost devoid of fat, 
and contains the superficial vessels and nerves. To this layer the skin owes its 
mobility. 
The fascia of the penis reposes on the erectile bodies. Anteriorly it does not 
enter into the formation of the prepuce, but passes directly to the base of the 
glans, where it fuses with the integument. Behind, it is continuous with the 
superficial perineal fascia and the suspensory ligament. Structurally it is com- 
posed almost entirely of elastic tissue, and it therefore acts as a compressor of 
the deep veins. 
Conformation and Fixation.—The anterior extremity or glans penis has already 
been described. The body, when flaccid, is soft, cylindrical in outline, and hangs 
vertically from the front of the symphysis, forming with the root an acute angle, 
the angle of the penis; when erect, it becomes much larger, changes in direction, 
and is prismatic in outline with rounded borders. The root is made up chiefly 
by the diverging crura. These are held in position by their insertion into the 
ischio-pubic rami, and by short fibrous bands, which unite them to the pubic 
arch, the symphysis, and the inferior layer of the triangular ligament. The 
suspensory ligament, a triangular band of elastic tissue, also aids in securing the 
root. Its apex is attached to the upper part of the symphysis and the neighbor- 
ing linea alba; its posterior border blends with the front of the symphysis; its 
anterior border is free. Below, its fibres divide into two groups, median and 
lateral. The former are inserted into the fascial sheath to the right and left of 
the dorsal vein, the latter separate to surround the cavernous bodies. 
Vessels.—The arterial supply (Fig. 884) of the envelops is derived from the 
external pudic, and from the superficial perineal and dorsal artery of the penis, 
CAVERNOUS 
BRANCH 
DORSAL ARTERY 
CORPUS CAVERNOSUM 
~GLANS PENIS 
ANTERIOR 
BRANCH 
CORPUS SPONGIOSUM 
•BULBOUS 
BRANCH 
-BULB 
INTERNAL PUDIC 
ARTERY 
Fig. 884.—Diagram of the arteries of the penis. (Testut.) 
branches of the internal pudic. Each cavernous body receives from the corre- 
sponding internal pudic a branch, which penetrates the albuginea on its inner 
side just behind the point where the converging crura meet. This vessel sends a 
recurrent branch to the crus, and then passes forward in the central axis of the 
body, anastomosing frequently through the fissures in the septum with its fellow. 
Small twigs from the dorsal artery of the penis also perforate the albuginea. 
The bulb and body of the corpus spongiosum are supplied by a branch (artery 
of the bulb) from each internal pudic. A smaller branch from the same source 
or from the transverse perineal also enters the dorsal surface of the bulb. The 
glans is supplied by the dorsal artery of the penis. In the erectile tissue the 
arteries are supported by the trabeculae, and are divided into two groups— THE PENIS. 
817 
nutritive and functional The former supplies the histological elements, breaking 
up into capillaries, which merge into veins in the ordinary way. The latter, 
according to Eckhard, forms bouquets of short terminal branches, which open 
into the areolae by means of small 
orifices. These orifices are sur- 
rounded by elastic tissue, which 
keep them closed when the penis 
is flaccid. Small convoluted twigs, 
called helicine arteries, are some- 
times seen projecting into the areolae. 
The veins (Fig. 885) from the 
envelops and the prepuce converge 
toward the dorsum of the organ, 
where they form a common canal, 
the superficial dorsal vein, which 
follows the median line, lying in 
the areolar layer beneath the dartos, 
and ends in the external pudic and 
obturator veins. The veins from 
the corpus spongiosum emerge along 
its whole length. Those from the 
glans pass backward to the excava- 
tion at its base, where they form the 
deep dorsal vein, which runs beneath 
the fascial sheath, in the superior 
groove formed by the cavernous 
bodies, and perforates the triangu- 
lar ligament to end in the prostatic 
plexus. Those from the body and 
bulb terminate in the same plexus or 
in the internal pudic veins. Small 
venous branches from the cavernous 
bodies emerge from both the superior 
and inferior surfaces; the former pass 
SUPERFICIAL DORSAL VEIN 
EXTERNAL PUDIC VEIN 
OS PUBIS 
OBTURATOR VEIN 
Fig. 885.—Veins of the penis. (Testut.) 
directly into the deep dorsal vein, the latter terminate in the same vessel after first 
encircling these bodies. The principal efferent trunk, however, conies from the 
posterior extremity of the cavernous body and perforates the triangular ligament 
to end in the prostatic plexus or the internal pudic veins. 
The lymphatics from the prepuce and envelops form a single superficial dorsal 
trunk, which accompanies the vein of the same name, and, dividing at the root 
of the penis into right and left 
branches, terminates in the super- 
ficial inguinal nodes. The deep 
lymphatics take origin in the erec- 
tile structures. In the glans they 
communicate freely with the lym- 
phatics of the urethra. Behind the 
glans they form a trunk, which fol- 
lows the deep dorsal vein, and ends 
in the internal iliac nodes. 
Nerves.—The coverings of the 
penis receive their nerve-supply from 
the genital branch of the genito- 
crural, and from the inferior perineal 
branch of the internal pudic. The 
SUPERFICIAL DOR- 
SAL VEIN 
DORSAL ARTERY j .DEEP DORSAL VEIN 
CORPUS CAVERNOSUM 
SKIN- 
AREOLAR 
' TISSUE 
CAVERNOUS... 
ARTERY 
DARTOS- - 
DEEP 
FASCIA 
BULBO-CAVERNOUS ARTERY 
ANTERIOR BRANCH 
URETHRA 
Fig. 886.—IThe penis in transverse section, showing the 
blood-vessels. (Testut.) 
CORPUS 
SPONGIOSUM 
erectile structures receive sympathetic branches from the hypogastric plexus, and 
spinal branches from the dorsal nerve of the penis and the superficial perineal. 818 
THE ORGANS OF GENERATION. 
THE PROSTATE GLAND. 
The prostate (“standing in front”) (Figs. 887,888) is a glandular body, situ- 
ated around the initial portion of the urethra. It develops at puberty, atrophies 
after castration, and in certain animals increases in size during the breeding 
season. 
EJACULATORY 
DUCT 
“ UTERUS 
t MASCULI NUS 
MOUTH OF EJACU-., 
LATORY DUCT 
VERUMONTANUM— 
...PROSTATE—CUT SURFACt 
OPENINGS OF 
PROSTATE GLAND 
GLAND OF 
COWPEH 
-MEMBRANOUS URETHRA 
GLAND OF 
fVc°WPER. // 
—A RIDGE OF 
MUCOSA 
BULBOUS 
URETHRA 
DUCT OF COWPER’S. 
GLAN D—LAID BARE 
.CORPUS SPON- 
GIOSUM—CUT SURFACE 
Fig. 887.—Proximal portion of the urethra, laid open hy a median, anterior cut. (Testut.) 
Form and Location.—It is irregularly cone-shaped, flattened from before back- 
ward, and is so directed that its central axis, running downward and forward 
from base to apex, makes with the vertical an angle of twenty to twenty-five 
degrees. It occupies the median line, lying below the bladder, above the tri- 
angular ligament, behind the symphysis, and in front of the rectal ampulla. 
Volume.—ln the child the prostate is only rudimentary in size ; but at puberty 
it begins to enlarge, attaining its full development from the twentieth to the 
twenty-fifth year. Its size, therefore, depends on the age of the subject. In the 
adult it is about one inch and a quarter in length (from base to apex), one and 
one-half inch in width at the base, a little over an inch in thickness, and it 
weighs from four to six drachms. After the sixtieth year of life, often earlier, 
the prostate frequently becomes enlarged to double or even triple its original size ; 
and this senile hypertrophy, which is probably always pathological, may be con- 
fined to the middle lobe, or may affect the entire organ. 
Conformation and Relations.—The gland presents for description a base, an 
apex, an anterior, a posterior, and two lateral surfaces. The posterior surface, 
looking backward and downward, rests on the anterior wall of the rectum, 
through which it may be felt above the internal sphincter and below and in front 
of the trigone of the bladder. This surface presents along the median line a 
shallow groove, which indicates the division of the gland into lobes. The anterior 
or pubic face, convex, shorter, and of less extent than the posterior, is turned 
toward the symphysis, from which it is separated by the prostatic plexus of THE PROSTATE GLAND. 
819 
veins, the pubo-prostatic ligaments, and the anterior ligament of the bladder. 
The lateral surfaces are convex, and covered by the anterior margins of the leva- 
tores ani muscles, the vesico-prostatic plexus of veins intervening. The base is 
situated immediately below the bladder, with the muscular fibers of which it is 
directly continuous. The apex rests on the upper surface of the superior layer of 
the triangular ligament, about half an inch behind the symphysis, and a little 
below the horizontal plane drawn through the highest point of the subpubic 
arch. 
The prostate is traversed from base to apex by the first portion of the urethra, 
which occupies the median plane, but is nearer to its anterior than to its posterior 
surface. The direction of the ejaculatory ducts has already been described. 
Lobes.—The prostate consists of two lateral lobes, which meet and become 
continuous both in front of and behind the urethra ; and this bilobed condition is 
indicated by a posterior median groove, the 
prostatic fissure, which lodges the vasa defer- 
entia and the vesiculae seminales. On median 
section, however, the gland is seen to consist of 
three parts, one in front of and two behind the 
the urethra. Of the two posterior divisions 
that above the ejaculatory ducts is called the 
third or median lobe. It is, of course, continu- 
ous at the sides with the lateral lobes. When 
slightly enlarged the median lobe forms a pro- 
jection on the middle zone of the base ; greater 
degrees of enlargement cause the posterior wall 
of the vesico-urethral opening to become convex, 
thus changing both the length and direction of 
MUSCULAR FIBRES OF BLADDER 
—CUT AT THEIR PROSTATIC INSERTION 
SEMINAL VESICLE 
VAS DEFERENS 
SINUS POCU LARIS 
Fig. 888.—Base of the prostate gland. 
(Testut after Sappey.) 
the urethra, and often interfering with micturition and the passage of sounds. 
Minute Structure.—Structurally the prostate consists of two principal ele- 
ments—stroma, and glandular tissue. The stroma, made up of connective tissue 
and smooth muscular fibres, forms for the prostate a sort of external capsule, in 
the thickness of which are lodged the veins of the prostatic plexus. By its 
outer surface this capsule is in contact and blended with the recto-vesical fascia 
and the superior layer of the triangular ligament. The inner surface of the 
capsule gives birth to a system of trabeculae, which, radiating toward the veru- 
montanum in the floor of the urethra, divide the gland into a number of triangu- 
lar spaces, in which is lodged the glandular tissue. The muscular fibres of the 
stroma are abundant, constituting about one half of the entire mass of the gland. 
Above, they are continuous with the muscular fibres of the bladder wall, and 
form a strong ring surrounding the urethra; below, they are mingled with 
a small amount of voluntary muscular tissue, derived probably from the trans- 
verse perineal muscles. 
The glands are of the branched or tubular variety, and number 30 or 40. 
They are disposed in a radiating direction around the urethra. Their ducts 
communicate with the urethra by minute orifices, opening into the prostatic 
sinuses on either side of the verumontanum. The glands are lined by a layer 
of columnar epithelium. They secrete a milky fluid, which at the moment of 
ejaculation is added to the seminal fluid. 
Vessels and Nerves.—The arterial supply is derived from the inferior vesical 
and the middle hemorrhoidal arteries. These furnish branches of small calibre, 
which ramify in the thickness of the organ, forming capillary plexuses around 
the walls of the glands. The veins empty into the plexus (vesico-prostatic), 
which surrounds the prostate, terminating finally in the internal iliac vein. The 
lymphatics take origin around the glandular walls, ramify with the venous plexus, 
and finally end in the internal iliac nodes. The nerves are branches of the hypo- 
gastric plexus. 820 
THE ORGANS OF GENERATION. 
THE BULBO URETHRAL GLANDS. 
The bulbourethral or suburethral glands, more commonly called the glands 
of Cowper (Fig. 887), are two firm, rounded, somewhat lobulated bodies, about 
the size of peas. They are situated between the two layers of the triangular 
ligament, one on either side of the membranous urethra, and immediately above 
the posterior extremity of the bulb. From the last they are separated by the 
inferior layer of the triangular ligament, and some fibres of the compressor 
urethrae muscle. 
Each of these bodies represents a compound racemose gland made up of 
several lobules, held together by fibrous tissue. The ducts of the lobules unite 
to form a single duct, which escapes from the gland at its anterior and superior 
aspect. The ducts from both glands pierce the triangular ligament, and con- 
verging, run forward beneath the mucous membrane for an inch or more, to 
open finally by minute orifices into the floor of the bulbous urethra. The acini 
of the glands are lined with pyramidal epithelium, the ducts by a finely granular 
epithelium disposed in two layers. The product of these glands is a viscid, 
transparent, albuminoid fluid, which is mixed with the seminal fluid at the 
moment of ejaculation. 
THE MUSCLES OF THE MALE PERINEUM. 
These are divided into two groups, according as they are closely related to the 
anal canal or to the genito-urinary organs. In the former set are the anal sphinc- 
Fig. 889.—Muscles of the male perineum. (Testut.) 
ters, the levatores ani, and the coccygei; in the latter are the transversi perinei, 
the ischio-cavernosi, the bulbo-cavernosi, and the constrictor urethrae. All are 
in pairs, excepting the sphincters (including the constrictor), which are bilaterally 
symmetrical. 
About an inch in front of the anus four of these muscles—one behind, one in 
front, and one on each side—unite in a small, tendinous area, called the central 
point of the perineum. THE MUSCLES OP THE MALE PERINEUM. 
821 
The Anal Group (Fig. 889). 
The internal sphincter has already been described in connection with the organs 
of digestion. 
Sphincter Ani Externus, “ the external sphincter of the anus,” surrounds the 
lower part of the anal canal. It is three or four inches long and two wide. It 
arises from the tip of the coccyx ; its lateral halves run forward, one on each 
side of the canal, and unite in front of it, where they presently become inserted 
into the central point of the perineum. It closes the anal canal. Its nerves are 
the fourth sacral and the inferior hemorrhoidal branch of the pudic. 
Levator Ani, “ the lifter of the anus,” forms the greater part of the floor of 
the pelvic cavity on each side. It arises partly from bone, but mostly from fascia 
upon a line which extends from the body of the os pubis to the ischial spine. 
Its insertions are all at lower levels than any part of its origin, the pelvic floor 
sagging in the middle. Its front fibres run backward to the central point of the 
perineum, embracing the prostate ; those at the rear pass mesially to the coccyx ; 
and those between the front and rear, constituting the bulk of the muscle, course 
toward the middle line, and are inserted some into the wall of the anal canal, and 
some into a median raphe in front of and behind the canal. Its upper surface is 
covered with the recto-vesical fascia. The two muscles, like all of the perineal 
muscles, act in concert. Their contraction lifts the pelvic floor and tends to 
counteract the action of the sphincters, thus aiding in defecation. They also 
assist in other expulsive movements by compressing the abdoraino-pelvic con- 
tents. The supplying nerves are the fourth sacral and the perineal branch of the 
pudic. 
Coccygeus, “the coccyx muscle,” completes the muscular floor of the pelvis on 
each side, so largely formed by the levator. It arises from the spine of the 
ischium, expands into a triangle, and is inserted into the margin of the coccyx 
and the last segment of the sacrum. It acts with the levator, and pulls the 
coccyx forward when it has been displaced backward, as in defecation. Its nerve 
is the fourth sacral. 
Transversus Perinei, “the transverse muscle of the perineum,” is sometimes 
called “ superficial ”to distinguish it from the “ deep transverse,”—a name often 
given to the constrictor urethrae. It arises from the mesial side of the tuber 
ischii, passes forward and inward, and is inserted into the central point, fusing 
with its opposite fellow, the external sphincter, and the bnlbo-cavernosus. Its 
nerve is the perineal branch of the pudic. The transversi serve to fix the central 
point, and thus aid the action of the other muscles which are attached to it. 
Ischio-cavernosus, named from its attachments, is also called erector penis. It 
arises from the mesial surface of the tuberosity and ramus of the ischium at the 
sides of the crus penis, thus embracing this structure. It is inserted into the 
external and inferior surfaces of the anterior part of the crus. It is supplied by 
the perineal branch of the pudic nerve. Its action, by compressing the crus, is 
to cause and maintain erection. 
The Genito-urinary Group (Fig. 889). 
Bulbo-cavernosus is thus named from its attachments to the bulb of the corpus 
spongiosum and to the corpus cavernosum. It is also known as the ejaculator 
urince, accelerator urince, and ejaculator seminis. From the central point of the 
perineum a tendinous raphe extends forward in the mid-line upon the bulb. 
This and the central point give origin on each side to one of these muscles, the 
fibres passing obliquely forward, embracing the bulb and the part of the corpus 
spongiosum just in front of it. The greater part are inserted on the dorsum of 
the spongy body, while the foremost fibres extend around the side of the cavern- 
ous body and are inserted on its dorsum in the mid-line. The perineal branch 
of the pudic nerve supplies it. The two muscles compress the hind part of the 
spongy urethra and drive its contents forward. 822 
THE ORGANS OF GENERATION 
Constrictor Urethrae, also named compressor urethrae, is enclosed between the 
two layers of the triangular ligament, and includes the membranous portion of 
the urethra, for which it acts as a sphincter. It is sometimes called the deep 
transverse muscle, because it extends across from side to side between the ischio- 
pubie rami. Part of it goes in front and part behind the urethra. It squeezes 
the membranous urethra, and thus expels its contents. The dorsal nerve of the 
penis supplies it. 
THE FEMALE ORGANS OF GENERATION. 
The female generative organs arc divided into an internal and an external 
group. The former are contained within the pelvis and comprise the following 
structures : (1) the ovaries, two glandular organs devoted to the production of the 
ova; (2) the Fallopian tubes, canals through which the ova reach the uterine 
cavity ; (3) the uterus, a single, median, hollow organ, which receives the fecun- 
dated ovum, provides it with nutrition, and expels it at maturity ; (4) the vagina, 
a canal by means of which the uterine cavity communicates with the external 
surface of the body. 
The external organs, grouped under the common term of vulva or pudendum, 
include the vulval canal and certain surrounding and contiguous structures. 
f INSERTIONS OF 
*) ROUND LIGA- 
I MENT 
Fig. 890.—Female pelvic viscera, from above. The ovary and tube of the left side have been lifted out of 
place. (Testut.) 
THE OVARIES. 
The ovaries (Figs. 890, 891), two in number, are the essential female organs 
of generation. They are firm, fibrous, ovoid bodies, situated in the retro-uterine THE OVARIES 
823 
compartment of the pelvis, where they are connected, one on either side of the 
uterus, with the posterior layer of the broad ligaments. On the surface of the 
abdominal wall, their position is indicated by the mid-point of a line drawn from 
the anterior superior spinous process of the ilium to the pubic symphysis. 
Dimensions, Color, and Consistence.—Each ovary is about an inch and a half 
in length, three-quarters of an inch in breadth, from one-third to one-half an 
inch in thickness, and weighs from one to two drachms. During pregnancy, the 
gland which contains the corpus luteum is much larger than its fellow. In the 
child the ovaries are rosy white, in the adult they are reddish ; and during men- 
struation, owing to the vascular engorgement, they assume a deeper tinge. They 
resemble the testicle in consistence, but are much less dense. In the old, the 
entire gland atrophies, and becomes hard and fibrous. 
Conformation and Relations.—Each ovary presents for examination two sur- 
faces, a superior or mesial, and an inferior or lateral; two borders, an anterior 
and a posterior; and two extremities, an external or superior, and an internal or 
inferior. The superior surface, convex and free, looks upward, forward, and in- 
ward, and is more or less covered by the fimbriae of the Fallopian tube and the 
meso-salpinx. The inferior surface, turned toward the side wall of the pelvis, 
often reposes in a shallow depression, the ovarian fossa, which is bounded behind 
and below by the internal iliac vessels and the ureter, above by the external iliac 
vessels, and in front by the pelvic attachment of the broad ligament. The 
anterior border, almost straight, is attached to the posterior layer of the broad 
ligament, between the layers of which the vessels and nerves run to enter the 
ovary at a depression in this border, called the hilum. The posterior border is 
free, turned toward the rectum, and covered to a varying extent by the fimbriae 
of the Fallopian tube. The superior extremity is rounded ; the inferior, more 
pointed, does not quite reach to the pelvic floor. (The relation which the ovary 
bears to the Fallopian tube will be included with a description of the latter 
structure.) 
Fixation.—The ovaries are held in position by their attached anterior borders, 
and by the utero-ovarian, the tubo-ovarian, and the suspensory ligaments. The 
FIMBRIAE 
UTERO-OVARIAN ( 
LIGAMENT _• 
HYDATID 
UTERO-OVARIAN 
VESSELS 
UTERINE VESSELS- 
DORSAL FOLD OF 
BROAD LIGAMENT 
OS UTERI VAGINA 
Fig. 891.—The uterus and appendages, front view. On the left side the tube is pulled down, the ovary lifted 
up. (Testut.) 
utero-ovarian ligament is a short rounded cord somewhat over an inch in length, 
which, running between the folds of the broad ligament, connects the inferior 
extremity of the ovary with the superior angle of the uterus, where it is attached 
a little below and behind the origin of the Fallopian tube. It is composed of 
fibrous tissue and plain muscular fibres, the latter derived from the superficial 824 
THE ORGANS OF GENERATION. 
muscular layer of the uterus. The tuba-ovarian ligament, or ovarian fimbria, 
connects the superior extremity of the ovary with the fimbriated extremity of 
the Fallopian tube. The suspensory ligament, also called the lumbo-ovarian liga- 
ment, or ligamentum infundibulo-pelvicum, is the upper part of the external border 
of the broad ligament. Running downward from the brim of the pelvis, it is 
attached to the superior extremity of the ovary and carries between its folds the 
ovarian vessels and nerves. 
Direction.—Usually the ovaries assume a slightly oblique direction, running 
downward, inward, and a little forward, so that their long axes, if extended 
below, would meet in front of the uterus. Their direction, however, varies 
widely within normal limits, and is much influenced by the fact that their liga- 
ments are not only extensible, but two of them, the utero-ovarian and tubo- 
ovarian, take origin from movable points. Another important factor in deter- 
mining the direction of the ovary is the condition of the neighboring organs. 
When the uterus deviates from the median line, the ovary of the side to which 
the uterus turns is vertical; while that of the opposite side, its lower extremity 
pulled ou by the utero-ovarian ligament, is nearly or quite horizontal. A full 
bladder or rectum, by changing the position of the uterus, must also modify the 
direction of the ovary. 
Structure.—The ovary consists of a framework of stroma, Graafian follicles, 
and an epithelial covering continuous with but differing from the peritoneum. 
The stroma(“bed”) is a connective tissue composed of abundant cells, white 
and yellow fibrous tissue, plain muscular fibres, blood-vessels, and nerves. Many 
of the cells are spindle-shaped, and are held by some anatomists to be cells of 
involuntary muscular tissue, while others regard them as connective-tissue cells. 
From the hilura there projects into the centre of the ovary a core made up wholly 
of stroma and called the medullary substance. It is very vascular and contains 
no Graafian follicles. From the periphery of this core numerous bands of stroma 
run toward the surface of the ovary, crossing and intersecting each other in every 
direction. Arrived at the surface, these bands reunite to form beneath the epi- 
thelial covering a thin fibrous layer, the tunica albuginea ovarii, which bears, 
however, but a faint resemblance to the tunica albuginea of the testicle, and can- 
not be dissected from the subjacent parenchyma. Between the tunica albuginea 
and the medullary substance is a thin zone called the cortical layer. It is only 
slightly vascular, and contains in various stages of development the Graafian 
follicles. The epithelial covering, composed of a single layer of columnar cells, 
reposes ou the tunica albuginea, and is the remains of the germinal epithelium. 
The peritoneum, covered by flattened epithelial cells, is totally unlike this 
structure, which it joins at the level of the attached anterior border. 
Graafian Follicles (Fig. 892).—The Graafian follicles contain the ova, and are 
embedded in the meshes of the ovarian stroma. Their structure depends on the 
degree of maturity which they have attained, and will therefore be described in 
several stages. 
The smallest follicles, varying in size from to of an inch in diameter, 
consist of a single layer of flattened or spindle-shaped cells, which closely invest 
a larger cell, the ovum. In the young child each ovary contains about thirty-six 
thousand follicles of this grade. 
In a second and mare advanced stage the following structural changes are 
noted: (1) The surrounding stroma forms for the follicle a special wall, divisible 
into two layers—an outer, fibrous layer (tunica fibrosa), which encloses the blood- 
trunks and lymphatic spaces of the follicle ; and an inner, vascular layer (tunica 
propria) composed of connective-tissue cells and a capillary plexus. (2) The 
spindle-shaped cells, which invested the ovum in the earlier stage, now become 
columnar and proliferate, making two layers, one of which lines the tunica 
propria, and is called the membrana granulosa, while the other invests the ovum 
and is known as the discus proligerus. (3) Between these two layers an albu- 
minous transparent liquid, the liquor folliculi, is developed; and it crowds the 825 
THE O VARIES. 
ovum to one side of the follicle, usually that nearest to the surface of the ovary, 
where the cells of the discus proligerus are continuous with those of the mem- 
brana granulosa. (4) Between the membrana granulosa and the tunica propria 
there appears a thin structureless membrane, the membrana propria. 
The largest follicles are from to Jan inch or more in diameter. Their 
increased size is due mainly to an increase of the liquor folliculi. In this stage 
the membrana granulosa and discus proligerus each consists of several layers of 
GRANULAR 
-MEMBRANE 
GRANULAR 
MEMBRANE- 
pOVUM / 
OVUM- 
ETICULAR 
PROPER- 
MEMBRANE 
GRANULAR 
• MEMBRANE 
PROPER- 
TUNIC 
-FIBROUS 
TUNIC 
LIQUOR 
FOLLICULI 
DISCUS ' 
PR O LI G E RUS 
OVUM 
PROPER 
MEMBRANE- 
-OVUM 
VITELLINE 
M EMBRANE 
GRANULAR 
MEMBRANE* 
1 
fff-V ITELLINE 
V/j MEMBRANE 
leucocytes in \ 
' RETICULUM 
Fig. 892.—Graafian follicles, in different stages of development. Diagrammatic. (Testut.) 
cells, derived by proliferation from the pre-existing cells. In the external layer, 
that is next to the tunica propria and the ovum, the cells retain their columnar 
outline, but the remaining layers are composed of irregular or rounded cells. 
Origin.—ln early foetal life, the ovary is represented by a cellular mass derived 
from the peritoneal cover of the Wolffian body, and called the germinal epithelium. 
Among the small cells of which it is composed are certain larger, spherical, 
nucleated cells, the primordial ova.. Soon, from the fibrous stroma beneath the 
epithelium, prolongations of connective tissue grow into the mass of cells; and 
coincident!y the cells, themselves becoming involuted at certain points, grow into 
the stroma. In this way irregular tubes lined with polyhedral or rounded cells 
are formed. Later, bands of stroma grow across these tubes and divide them into 
nests of cells. These nests are the future Graafian follicles, and each contains at 
least one primordial ovum. From the smaller cells are developed the membrana 
granulosa and discus proligerus. By about the seventh month of intra-uterine 
life these processes cease, and thereafter the ovary is covered by the single layer 
of epithelium already described. 
Location.—The smallest follicles are found in the outer layer of the cortical 
zone of the ovary, where they are so numerous as to impart to this region a granu- 
lar appearance. Many of these never develop. The larger follicles (ten to twenty 
in each ovary) occupy the deeper layer of the cortical zone. The largest and most 
mature follicles are in contact with the medullary substance and nourished by its 
rich vascular supply. Extending entirely across the cortical layer, they project 
from the surface of the ovary in the form of clear vesicles, to of an inch in 
diameter. 
At puberty a certain number of follicles become enlarged, and from that time 
until the climacteric new ones are being constantly developed. 
Structure of the Ova.—The human ovum in the primordial stage is about 
ToVo °f an inch in diameter, in the mature stage its diameter is increased to 
of an inch. It is developed from a nucleated cell and presents the following 
parts: (1) an outer covering representing the cell wall, and called the zona pel- 
lueida or vitelline membrane; (2) within this a mass of protoplasm, the vitellus or 826 
THE ORGANS OF GENERATION. 
yolk; (3) situated excentrically in the vitellus the germinal vesicle, which repre- 
sents the nucleus of the cell; (4) the nucleolus or germinal spot. 
The zona pellucida, a thick strong and transparent membrane, forms the outer 
covering of the ovum. It is marked by numerous radiating striae, and for this rea- 
son is sometimes called the zona radio,ta. The striae are supposed to be minute canals, 
through which nutrition reaches the ovum, while it is still in the Graafian follicle, 
and through which the spermatozoa may afterward pass in the process of fecunda- 
tion. The yolk or vitellus is a soft substance contained within the zona radiata. 
It consists of granules embedded in a fine reticulum of protoplasm. The germinal 
vesicle, to °f an inch in diameter, lies near the periphery of the ovum. 
It is composed of a structureless membrane, containing a fine clear matrix, in 
which are embedded a few granules. The germinal spot, or nucleolus, ygVo' 
o' an *n diameter, occupies the side of the germinal vesicle nearest to 
the periphery of the ovum. There may be more than one. 
Origin.—The primordial ova are scattered among the other cells of the germi- 
nal epithelium, and with them descend into the substance of the ovary, as already 
described. Some, however, remain behind, and are found among the single layer 
of columnar cells, which covers the surface of the ovary. These probably undergo 
no further development. 
Discharge.—Rupture of a Graafian follicle, and sometimes more than one, 
occurs shortly before or during each menstrual period. It takes place at a point 
in the peripheral pole of the follicle called the stigma (“ point ”) or macula 
(“ spot ”) folliculi. The wall at this point is scantily supplied with blood-vessels, 
and, as the follicle nears maturity, it undergoes fatty degeneration. The ovum 
with the liquor folliculi and cells of the discus proligerus is discharged on the 
surface of the ovary. 
Corpora Lutea.—A corpus luteum (“ yellow body ”) occupies the site of each 
ruptured Graafian follicle, and is produced by certain changes which take place in 
the follicular wall. A short time before the follicle is ready to rupture, the cells 
of the tunica propria begin to proliferate, and the wall of the follicle is thrown 
into folds, into which project newly formed vascular loops. A blood-clot fills the 
follicle after rupture, but it is soon absorbed and the folds, growing into the 
cavity, take its place. In the non-pregnant the whole structure begins to shrink 
in about two weeks, and in a short time disappears. The corpus luteum of preg- 
nancy differs much from that just described. It is larger and persists for a longer 
time. As the blood-clot disappears, a peculiar yellowish connective tissue (yel- 
low probably because the cells are loaded with oil-globules) takes its place. After 
several months the corpus luteum ceases to grow, but it is still present, though 
much reduced in size, even at the end of pregnancy. 
The surface of the ovary is smooth until puberty. After that time it grows 
more and more uneven, due to the scarring which follows the formation of the 
corpora lutea. 
Vessels and Nerves.—Each ovary is supplied with blood by a branch from 
the abdominal aorta, the ovarian artery, which corresponds to the spermatic in 
the male. This vessel is carried to the ovary between the layers of the suspensory 
ligament. It divides into two branches : a tubal, distributed to the Fallopian 
tube, and an ovarian. The latter runs in a flexuous course along the attached 
border of the ovary, to which it sends from ten to twelve branches, and ends by 
anastomosing with the uterine artery near the superior angle of the uterus. The 
branches to the ovary, also tortuous, end in capillary plexuses in the tunica 
propria of the Graafian follicles. The veins form in the middle of the organ a 
considerable mass, called the bulb of the ovary. Emerging from the hilum, these 
vessels join with some of the uterine veins to form between the layers of the 
broad ligament the pampiniform (“ tendril-form ”) plexus. From this the blood 
is collected by a single trunk, the ovarian vein, which follows the course of the 
corresponding artery. The right ovarian vein empties into the inferior vena cava, 
where it is supplied with a valve. The left joins the renal vein at a right angle, THE FALLOPIAN TUBES. 
827 
and is without valves. The lymphatics begin as minute spaces in the tunica 
fibrosa of the follicles, around which they form plexuses. At the hilum they are 
condensed into five or six trunks; and, following the veins, they finally empty 
into the lumbar nodes. The nerves are derived from the ovarian plexus of the 
sympathetic. An additional supply is probably received from the uterine nerves, 
branches of the third and fourth sacral. 
Migration.—The ovaries are situated primarily in the lumbar region, in front 
of the psoas, and near the kidney. About the third month of intra-uterine life 
they begin to descend, and at the ninth month they reach the brim of the pelvis. 
This descent is chiefly due to the fact that the lumbar region grows away from 
the ovary. Sometimes, though rarely, the gland may remain in its primitive 
situation, or it may descend into the inguinal canal, even passing through the 
external abdominal ring. 
THE FALLOPIAN TUBES. 
The Fallopian tubes, or oviducts (“ egg-ducts ”) (Figs. 890, 891), two in 
number, are the excretory ducts of the ovaries and serve to convey the ova to 
the uterine cavity. 
Location.—They are situated in the free or upper margin of the broad liga- 
ments, between the ovaries behind and the round ligaments in front. Internally 
they are continuous with the superior angles of the uterus, externally each tube 
is attached to the superior or outer extremity of the corresponding ovary. That 
portion of the broad ligament below each tube, and between it and the ovary, is 
called the meso-salpinx (“ mesentery of the tube ”). The oviducts are, therefore, 
fixed in position by their continuity with the uterus, by their attachments to the 
ovaries, and by their imprisonment between the two peritoneal laminae, of which 
the broad ligaments are composed. 
External Conformation.—Each tube is trumpet-shaped, and increases in size 
from within outward. At the ovarian extremity, it expands to enclose a funnel- 
shaped space, the infundibulum or pavilion. It varies in length from four to five 
inches, and is divided into three parts as follows : (a) the inner extremity or 
interstitial portion ; (6) the middle portion or body; (c) the external or fim- 
briated extremity. The interstitial portion is contained in the thickness of the 
uterine wall. Its canal, very narrow, is continuous with the uterine cavity 
through a small opening, the ostium uterinum (“ door of womb ”), which is only large 
enough to admit a small bristle. The body is subdivided into two parts, an inner 
or isthmus and an outer or ampulla. The isthmus is hard, cylindrical, straight, 
and nearly horizontal. It measures an inch and a half in length, and has a 
diameter of about one-eighth of an inch. The canal of this division is still very 
small, though somewhat increased as compared with that of the interstitial por- 
tion, with which it is continuous. The ampulla (“bottle”) or receptaculum 
seminis (“ reservoir of seed ”) extends from the isthmus to the fimbriated 
extremity. It is distinguished from the former by the fact that it has thinner 
walls, and is softer, and flattened antero-posteriorly. It is also markedly flexuous, 
and the diameter is almost twice that of the isthmus. Its canal, increased in 
size toward the outer extremity, is irregular in calibre, and large enough to admit 
a uterine sound. 
The fimbriated extremity (infundibulum) opens downward, backward, and 
inward. It is the most movable part ot the tube, and receives the ova after 
their discharge from the Graafian follicles. This extremity may be divided for 
description into an internal and an external surface, a base and a summit. The 
external surface, continuous with the outer surface of the tube, is smooth and 
covered by visceral peritoneum. The internal surface is continuous with the 
corresponding surface of the ampulla, and lined by a prolongation of its mucous 
membrane. At the summit, the infundibulum communicates with the cavity of 
the ampulla through a narrow opening, a line to a line and a half in diameter, 828 
THE ORGANS OF GENERATION. 
called the ostium abdominale. The base is festooned by ten to fifteen diverging 
processes, called fimbrioe, (“ fringes ”), which are arranged in two or three con- 
centric circles. The bases of these are attached, their apices are free, and their 
edges are cut into numerous secondary fringes. The ovarian fimbria, longer than 
its fellows, runs from the lower part of the ampulla, to become attached to the 
superior extremity of the ovary. On its inner surface a gutter, lined by mucous 
membrane, extends from the ovary to the ostium abdominale. By its outer 
surface it is in contact with a band of smooth muscular fibres continued from the 
muscular tunic of the tube. Sometimes the ovarian fimbria is not quite long 
enough to reach the ovary ; it is then attached through the medium of this mus- 
cular band, which also carries the terminal portion of the mucous gutter. 
Internal Conformation.—The canal, as already stated, increases in diameter as 
it passes outward. Its mucous membrane is thrown into folds, making a system 
of longitudinal plications, which extend throughout the whole length of the 
canal. In the interstitial portion and isthmus these folds are simple ridges 
separated by shallow grooves. In the ampulla they increase in number and 
volume; and the larger, extending clear across the canal, may bear on their 
sides secondary folds. The outer ends of these plications cross the ostium 
abdominale and are continued on to the inner surface of the fimbrise. 
Direction.—The Fallopian tubes are freely movable particularly in their outer 
portion. They are pushed backward by a full bladder, depressed by intestinal 
folds from above, or pushed forward when the intestines occupy the retro-uterine 
space. They are affected, too, by any change of position in the uterus. The 
direction which they pursue is therefore variable. Usually each tube runs from 
its inner extremity transversely outward to a point opposite the middle of the 
ovary, a distance of half an inch to one inch. It then runs upward, also a little 
backward and outward, in front of the attached border of the ovary, near to and 
parallel with the pelvic wall. Arrived at the superior extremity of the ovary it 
bends backward, and, after a short course in this direction, terminates by running 
inward and downward. It thus forms a sort of bay whose concavity, directed 
downward and inward, embraces the upper end of the ovary, while the fimbriae 
lie in contact with the posterior border and mesial surface of the gland. 
Structure.—The tube has three tunics—serous, muscular, and mucous. The 
two laminae of the broad ligament furnish the serous covering, and these, as they 
approach the tube, diverge, leaving along its lower border a narrow uncovered 
strip. A layer of loose areolar tissue, continuous with the subperitoneal fascia 
and rich in elastic fibres and blood-vessels, is found beneath the serous coat. The 
muscular tunic may be divided into two layers, longitudinal and circular. The 
former is superficial and continuous internally with the uterine muscle; externally 
it ends at the origin of the pavilion, except for the band, already mentioned, 
which accompanies the ovarian fimbria. The circular layer, also continuous with 
the uterine muscle, is thinnest near the fimbriated extremity, and ends at the 
ostium abdominale. In the vicinity of the uterus some longitudinal fibres are 
found within the circular. The mucous coat is continuous with the mucous lining 
of the uterus. Having no special submucosa, it is intimately adherent to the 
muscular layer. It forms the plications already described, and is lined by a 
single layer of columnar, ciliated epithelium, in which the ciliary motion is 
toward the uterus. Crossing the ostium abdominale the mucous membrane 
establishes itself on the inner surface of the fimbriae. At the borders of the 
latter, or on their outer surfaces a little beyond the borders, it merges into the 
peritoneum. It has no glands. 
Vessels and Nerves.—Arteries.—The external tubular artery is derived from 
the ovarian, the internal tubular from the uterine. Together these form an 
arcade, which travels between the layers of the meso-salpinx, and sends branches 
to the lower borders of the tube. The veins form in the meso-salpinx a plexus 
parallel to the axis of the tube, and finally empty through the pampiniform 
plexus into the utero-ovarian veins. The lymphatics, joining with those of the THE UTERUS. 
829 
ovary and uterus, empty into the lumbar nodes. The nerves, derived from a 
plexus around the uterine and ovarian arteries, are numerous; but their course 
and mode of termination are not well known. 
THE UTERUS. 
The uterus or womb (Figs. 890, 891, 893), a hollow organ with thick, muscular, 
contractile walls, is situated in the pelvis between the bladder and the rectum. 
' (% 
CLITORIS'— 
Fig. 893.—Sagittal section of the lower part of a female trunk, right segment. (Testut.) 
In its cavity the ovum is received, retained, and developed; and the foetus, after 
reaching maturity, is expelled chiefly by the contractions of its muscular fibres. 
External Conformation.—The uterus, in form, resembles a truncated cone, 
whose base, turned upward, reaches to or a little above the level of the pelvic 
brim ; and whose summit, directed downward, projects into the upper extremity 
of the vagina. It is flattened from before backward, and divided into two parts 
by a slight circular constriction, called the isthmus, which corresponds externally 
and in front with the point at which the peritoneum is reflected from the uterus 
to the bladder, while internally it coincides with a narrowing of the uterine canal, 
known as the internal os. In virgins the isthmus is a little below the middle of 830 
THE ORGANS OF GENERATION 
the long axis of the uterus; in women who have borne children it is placed at 
the junction of the middle and lower thirds. It divides the uterus into the body 
above and the cervix below. 
The body presents for description two surfaces, two borders, two extremities, 
and two angles. The anterior surface is slightly, the posterior markedly, convex 
and both are covered by peritoneum. The lateral borders, also convex, converge 
a little as they run downward to the isthmus. The superior extremity or fundus 
(sometimes called a border) is broad, convex, and covered by the peritoneum, as 
it passes from the anterior to the posterior surface. At the inferior extremity 
the body is continuous with the cervix. The angles, right and left, are formed 
by the junction of the superior extremity with the lateral borders. They are 
continuous with the corresponding Fallopian tubes. 
The cervix, narrower than the body and cylindrical in form, has a slightly 
wider diameter in the middle than at either extremity. It is continuous above 
with the body, below it projects into the vagina, which is attached around its 
circumference somewhat higher behind than in front. That portion above the 
vaginal attachment (supra-vaginal segment) comprises about two-thirds of the 
total length of the cervix in front, about one half behind. The middle or vaginal 
segment—that part to which the vagina is attached—is about one-tifth of an 
inch in length, and is placed obliquely. The lower or intra-vaginal segment is 
cone-shaped, covered by mucous membrane like that of the vagina, and presents 
at its summit a circular or transverse aperture, the external os. 
Internal Conformation.—The cavity of the uterus is divided into two parts 
by the internal os. The upper portion belongs to the body, the lower to the 
cervix. The long axes of these segments may lie in the same straight line, but 
usually they join to form an angle, opening anteriorly, of 140° to 170° (Testut). 
The cavity of the body (Figs. 894, 895), triangular in outline and with the 
FUNDUS 
CORPUS— 
INTERNAL OS- 
UPPER LIMIT 
OF CERVIX 
CANAL OF 
CERVIX 
SUPRAVAGINAL 
CERVIX 
VAGINAL. 
FORNIX 
VAGINAL 
1 FORNIX 
Pig. 894—The uterus of a virgin, in coronal 
section. 
EXTERNAL OS VAGINA 
Fig. 895.—The uterus of a woman who has borne a 
child, in coronal section. 
base uppermost, presents two surfaces, three borders, and three open angles. 
The surfaces, anterior and posterior, are in contact. All the borders, in the 
virgin, are convex internally; in women who have borne children the two lateral 
are straight or even concave. At the superior angles the cavity of the body 
communicates with the oviducts, at the inferior angle, or internal os, it is con- 
tinuous with the cervical canal. 
The cavity of the cervix, fusiform in outline, presents two surfaces, two 
borders, and two openings. The surfaces, distinguished as anterior and posterior, 
are in contact. On each may be seen a peculiar formation, the arbor vitae uterina 
(“ cedar of the womb ”), consisting of a median longitudinal ridge, from which THE UTERUS. 
831 
secondary and parallel ridges pass upward and outward to the lateral borders. 
In these ridges are smooth muscular fibres derived from the internal muscular 
layer of the uterine wall. The borders, situated laterally, are concave internally, 
thus widening the central portion of the cavity. The superior opening (os uteri 
internum) is not a simple opening, but a short canal. The inferior opening (os 
uteri externum) is usually a transverse aperture, about one-twelfth of an inch in 
length. It is bounded by two lips, an anterior and a posterior. The latter is 
the longer, due to the higher attachment of the vagina behind, but the former is 
placed on a lower level and hence appears on palpation to be the longer. Both 
are normally in contact with the posterior vaginal wall. The outline of the 
external os is much modified by child-bearing. 
Dimensions, Consistence, and Weight.—The uterus is about three inches in 
length, one and one-half to two inches in breadth at the upper and widest part 
of the body, and nearly an inch in thickness. In women who have borne 
children these diameters are all increased. The walls are about three-eighths 
of an inch in thickness. After death they are dense and resisting, but during 
life they are soft enough to retain sometimes the imprint of contiguous intestinal 
folds. The whole organ varies in weight from seven to twelve drachms. 
Direction.—The direction of the uterus is variable, and much influenced by 
the condition of the surrounding organs. Thus, a full bladder will push the 
uterus toward the sacrum, a full rectum will press it forward. When the bladder 
and rectum are empty, the fundus looks toward the umbilicus, and the uterus 
forms with the vagina a right or slightly obtuse angle. As a rule, the organ 
does not occupy the median line of the body, but is somewhat deflected, usually 
to the right. There is also present a certain amount of torsion, by means of 
which the left superior angle is carried a little farther forward than the right. 
Peritoneum (Fig. 896).—The peritoneum is reflected from the bladder to the 
anterior surface of the uterus at a level which usually corresponds to the isthmus, 
but may be slightly above or below. 
It then invests in the order named the 
anterior surface of the body, the fun- 
dus, the posterior surface of the body, 
and the posterior surface of the supra- 
vaginal segment of the cervix. It is 
also continued downward over the 
upper fourth of the posterior vaginal 
wall, and is then reflected to the 
front and sides of the rectum. At 
the lateral borders of the uterus the 
peritoneum from the anterior surface 
joins with that from the posterior 
to make up the broad or lateral liga- 
ments. Certain portions of the cervix 
have thus no peritoneal covering. 
They are the intra-vaginal and vaginal 
,RECTAL PERITONEUM 
POUCH 
ANTERIOR AND POS- 
TERIOR LAYERS OF 
BROAD LIGAMENT 
VESICAL 
■ PERITON EUM 
VESICO-UTERINE 
POUCH 
Fig. 896.—The cervix uteri and upper end of the 
vagina, showing their relations to the peritoneum. 
Diagrammatic. (Testut.) 
segments, and the anterior surface of the snpra-vaginal portion. This latter 
rests against the bladder from which it is separated by areolar tissue, continuous 
with the subperitoneal fascia. Areolar tissue is also found covering the lower 
part of the posterior surface of the uterus, and extending outward between the 
layers of the broad ligaments. 
Peritoneal Pouches.—The peritoneum, as it dips into the recess between the 
bladder and the uterus, forms a shallow pouch, the utero-vesical, which is occupied, 
when the bladder is empty, by coils of small intestine. Behind the uterus it forms 
a second and deeper pouch, the recto-vesical, or cul-de-sac of Douglas. This is 
limited in front by the cervix and upper part of the vagina, behind by the 
rectum, and laterally by two folds of peritoneum, the folds of Douglas, which 
extend from the cervix in front to the sides of the rectum behind. The folds 832 
THE ORGANS OF GENERATION. 
of Douglas, together with the smooth muscular fibres contained between their 
layers, constitute the utero-sacral ligaments. Coils of small intestine frequently 
occupy the upper, but are rarely found in the lower, part of the recto-vaginal 
pouch. 
Ligaments.—The uterus is maintained in position by six important ligaments, 
arranged in three pairs. They are the broad or lateral, the round, and the utero- 
sacral. 
The broad or lateral ligaments, two in number, extend from the lateral borders 
of the uterus and upper part of the vagina outward to the lateral walls of the 
pelvis, where they merge into the parietal peritoneum. They are composed of 
two apposed, serous laminae, which are continuous with the peritoneum covering 
the anterior and posterior surfaces of the uterus. Between these laminae are 
found the following structures : (a) the Fallopian tube; (6) the ovary and its 
ligament; (c) the round ligament; (d) blood-vessels and lymphatics ; (e) nerves; 
(/) remains of certain foetal structures; (</) smooth muscular fibres; (A) areolar 
tissue, rich in fat and continuous with the subperitoneal fascia. Each ligament 
has two surfaces and four borders. At the superior border, which is free, the 
laminae are continuous and enfold the Fallopian tube. The inferior border 
is attached to the floor of the pelvis, areolar tissue intervening between 
it and the recto-vesical fascia. The ureter crosses obliquely beneath this 
border. The external border is divided into two portions, upper and lower. 
The latter is firmly attached to the pelvic fascia, and transmits the uterine 
artery and the round ligament. The upper and shorter portion is free, and con- 
nects the fimbriated extremity of the Fallopian tube with the side of the pelvis. 
It is called the ligamentum infundibulo-pelvicwm, and carries between its layers 
the ovarian vessels. (This is usually described as a part of the superior border.) 
The internal border is in relation with the side of the uterus and upper part of 
the vagina, and lying between its laminae are the utero-vaginal vessels. The 
anterior lamina, shorter than the posterior, is in relation with the bladder. It is 
partially raised from the posterior by the round ligament, over which it falls in 
a more or less definite fold. The posterior lamina, directed toward the rectum, 
gives off a special extension to enclose the ovary and its ligament. The fold or 
extension surrounding the Fallopian tube is sometimes called the meso-salpinx ; 
between its layers there are no muscular fibres. 
The smooth muscular fibres of the broad ligaments are derived from the 
superficial muscular layer of the uterus. Passing outward between the laminae, 
they become attached to the pelvic fascia and help to sustain the uterus. With 
the areolar tissue they also form a support for the blood-vessels. 
The round ligaments, about five inches in length, are also symmetrically ar- 
ranged, one on either side. Each takes origin from the corresponding superior 
angle of the uterus in front and a little below the attachment of the Fallopian 
tube. From this point it runs obliquely forward and outward to gain the internal 
abdominal ring. Entering this, it traverses the inguinal canal, and, after 
emerging from the external ring, it finally ends in the tissues of the labia majora 
and mons Veneris. It is divided into four portions—pelvic, iliac, inguinal, and 
vulvar. The direction of the pelvic portion is at first a little downward, then 
upward as it emerges from the pelvis. The iliac portion, lying behind the 
peritoneum, crosses in front of the external iliac artery and vein. At the 
internal ring the ligament winds around the outer side of the deep" epigastric 
artery, and the inguinal portion gives off fibres, which are attached to the walls 
of the canal. The vulvar portion breaks up into numerous divergent, connective- 
tissue filaments, some of which are attached to the symphysis, while the remainder 
are lost in the tissues of the mons and labia majora. Structurally the round 
ligaments are composed of plain and striated muscular fibres, areolar tissue, 
blood-vessels, and nerves. The plain fibres are derived from the superficial 
muscular layer of the uterus; the striated, found only in the distal portion of the 
ligament, are acquired from the internal oblique and transversalis muscles and THE UTERUS. 
833 
represent the cremaster in the male. They help to attach the ligament to the 
pillars of the external ring and the pubic spine. A tube of peritoneum, repre- 
senting the processus vaginalis, accompanies the ligament into the inguinal canal. 
It sometimes remains pervious even in the adult, and is called the canal of Nuck. 
The utero-sacral ligaments are partly serous, partly of smooth muscular fibres. 
The serous portions are identical with the folds of Douglas already described. 
They extend between the cervix and sides of the rectum, forming the lateral 
boundaries of the recto-vaginal pouch. The muscular fibres are continuous with 
the superficial muscular layer of the uterus and vagina. Running between the 
layers of the folds of Douglas they serve to connect the cervix and vagina with 
the sacrum. 
The peritoneum at the bottom of the utero-vesical pouch is sometimes referred 
to as the anterior ligament of the uterus, while that which floors the recto-vaginal 
pouch is called the recto-vaginal ligament. 
Minute Structure.—The uterus consists of three coats—serous, muscular, and 
raucous. The serous coat has already been described. 
The muscular coat makes up the bulk of the uterine walls. It is dense and 
resisting, cuts with a grating sound, and is grayish on section. It is composed 
of smooth muscular fibres, intermingled with areolar tissue, vessels, and nerves. 
The arrangement of these fibres is very complex, but in the gravid uterus they 
may be divided into three layers, which are, however, not entirely independent. 
The mucous membrane lining the body of the uterus is intimately adherent to 
the internal muscular layer. It is pale and smooth, and presents the openings of 
numerous glands. Its external layer, or corium, is composed of embryonic con- 
nective tissue in which may be seen numerous round, spindle-shaped, or irregular 
cells. Lining this is a single, ciliated, columnar epithelium, the ciliary motion 
being from within outward. The glands are of the tubular variety, bounded by 
a basement membrane, and lined by ciliated, columnar epithelium, continuous 
with that found on the free surface. They pass obliquely or take a tortuous 
course through the corium ; and their blind extremities, single, bifurcated, or 
even trifurcated, repose on the internal muscular layer, or penetrate between its 
fibres. The ciliary motion in the glands is toward the uterine cavity. 
The mucous membrane of the cervix differs from that of the body. It is 
firmer and thrown into numerous folds, the ridges of the arbor vitse already 
described. The corium has fewer cell-elements, but is richer in fibres. The 
epithelium in the upper part of the cervix is the same as that found in the body; 
below, at the level of the external os or a little higher, it changes into a laminated 
epithelium, continuous with that which lines the vagina and covers the external 
surface of the os. The glands, tubular and racemose in type, are numerous and 
open between the ridges. They are lined in their deeper portions by goblet cells, 
and produce a thick alkaline mucus. Sometimes by the occlusion of their open- 
ings these glands become cystic ; they then appear as clear or yellowish vesicles, 
and are called the ovula of Naboth. Vascular papilhe are found in the lower part of 
the cavity of the cervix, and over the outer surface of its intra-vaginal segment. 
In the latter situation there are no glands. 
Structural Modifications During Menstruation and Pregnancy.—ln menstruation 
the more important changes take place in the mucous membrane of the body, 
which increases in vascularity and becomes thickened. Following this there are 
disintegration and removal of the superficial part of the membrane, the process 
beginning at the internal os and extending toward the fundus. Regeneration, 
brought about by a proliferation of the cells which remain in the deeper portions 
of the glands, is rapid and complete. In these changes the cervix takes little or 
no part. In gestation the whole organ becomes immensely hypertrophied, 
increasing in weight from an ounce to a pound and a half or even more. The 
muscular fibres not only increase in size, but in the early months new ones are 
added. The mucous membrane is at first the seat of changes similar to those 
which occur in menstruation, but these proceed further, and later bring about the 834 
THE ORGANS OF GENERATION. 
formation of the decidua. The membrane, as soon as the ovule has been engrafted 
upon it, loses its cylindrical epithelium while the cells of the corium increase. 
The ridges of the arbor vitae disappear ; otherwise there is but little change in the 
cervix. At parturition the greater part of the mucous membrane is destroyed to 
be restored in twenty to twenty-five days by the same method as after men- 
struation. 
Following parturition the uterus never attains its former (virgin) size. 
Variations Depending on Age.—-In the foetus, the uterus is contained in the 
abdominal cavity, the cervix is larger than the body, the fundus is undeveloped, 
and the ridges of the arbor vitae are distinct. At puberty, the cervix and body 
are about equal in length, and the fundus has reached the level of the pelvic brim. 
In the old the entire organ atrophies. 
Vessels and Nerves (Fig. 897).—The arteries which supply the uterus are 
arranged in three pairs—the uterine, the funicular, and the ovarian. The uterine 
artery is a branch of the anterior division of the internal iliac. From its origin 
TUBAL VESSELS 
ANASTOMOSIS OF 
UTERINE AND 
OVARIAN ARTERjES 
HELICINE BRANCHES \ 
FALLOPIAN 
TUBE 
I 
UTERINE VENOUS PLEXUS/ 
P UTERO- 
* SACRAL 
h ■' LIG A - 
i I WENT 
l-ROUND LIGAMENT 
ARTERY 
VAGINAL VENOUS PLEXUS 
VAGINAL 
ARTERIES 
Fig. 897.—Vessels of the uterus and its appendages, rear view. (Testut.) 
Os uteri' Vagina cut open behind 
it descends along the pelvic wall into the base of the broad ligament, then, taking 
a horizontal course, it crosses in front of the ureter and reaches the side of the cer- 
vix at the level of the vaginal insertion or a little below. From this point it is 
reflected upward, running close beside the lateral border of the uterus until it 
reaches the superior angle, where it ends by dividing into two branches, one of 
which anastomoses with the ovarian artery while the other is distributed to the 
Fallopian tube. From the ascending portion of the vessel numerous transverse 
tortuous branches are given off to the anterior and posterior surfaces of the uterus. 
These penetrate the uterine walls, and ramify in the middle muscular layer, where 
they divide into two sets of branches, superficial and deep. The former return to 
supply the outer muscular layer and the serous coat, the latter are distributed to 
the mucous membrane, forming plexuses in its superficial layers and around the 
glands. At the level of the isthmus the transverse branches are larger than else- 
where, and, with the corresponding divisions of the opposite artery, they form on 
the outer surface of the uterus the arterial circle of Huguier. Several small 
branches to the bladder and vagina arise from the uterine artery at or near its 
point of reflection. The funicular (“ pertaining to a rope”) artery, from the 
superior vesical, joins the round ligament at the internal abdominal ring and 
divides into two branches, superior and inferior. The former accompanies the 
ligament to the superior angle of the uterus, where it anastomoses with the uterine 
and ovarian arteries; the latter follows the ligament to its distal termination, THE VAGINA. 
835 
communicating there with the external pudic. The ovarian artery—described 
with the ovary—aids in supplying the uterus through its communications with 
the uterine and funicular arteries. The veins, which are very large, have no 
valves. Taking origin in the capillary plexuses, they converge to form a set of 
special canals, the uterine sinuses, which are lodged in the meshes of the middle 
muscular layer. From this point they are directed to the lateral borders of the 
uterus, where they form between the layers of the broad ligament the uterine 
plexuses, one on either side. From these the blood is collected by three trunks. 
One, the uterine vein, accompany hi g the artery of that name, empties into the 
internal iliac vein ; a second, by its junction with the veins from the ovary and 
Fallopian tube, helps to make up the pampiniform plexus; while a third (unim- 
portant) trunk follows the funicular artery. The lymphatics of the mucous mem- 
brane begin as minute spaces between the fibres of the corium. Joined by the 
lymphatics of the muscular coat, they emerge and form beneath the serous cover- 
ing a rich plexus, from which the lymph is carried by three trunks. The first, 
collecting chiefly from the body of the uterus, the ovary, and the Fallopian tube, 
accompanies the ovarian vein and empties into the lumbar nodes ; the second, 
carrying lymph from the cervix, follows the uterine vein, and ends in the pelvic 
nodes ; while the third, following the vein of the round ligament, ends in the 
inguinal nodes. The nerves, consisting of both medullated and non-medullated 
fibres, are derived from the inferior hypogastric and renal plexuses of the sym- 
pathetic, and from the third and fourth sacral nerves. 
The foetal remains to be observed in connection with the uterus or its adnexa 
are the parovarium, the duct of Gartner, the organ of Giraldes, and the hydatid 
of Morgagni. 
The parovarium (epoophoron, or organ of Rosenmfiller) is a vestige of the 
Wolffian body, and represents the vasa efferentia of the testicle. It consists of 
twelve to twenty tubules, arranged in the form of a triangle, and contained in the 
thickness of the broad ligament, between the ovary and the Fallopian tube, where 
it may be seen by holding the ligament against the light. The apex of the 
triangle reaches to the attached border of the ovary, the base is turned toward the 
Fallopian tube. The ovarian ends of the tubules are blind ; their opposite 
extremities open into a collecting duct which runs parallel with the outer portion 
of the Fallopian tube, and represents the canal of the epididymis. Both the col- 
lecting duct and the tubules are lined with a ciliated, columnar epithelium. 
The canals of Gartner, always present in certain animals, are the remnants of 
the lower portions of the Wolffian ducts. The latter, in the male, develop into 
the tail of the epididymis and the vas deferens; in the female they usually dis- 
appear. When persistent, however, they are found, as minute tubes or fibrous 
eords, one on either side of the uterus and vagina. Above, these tubes may be 
continuous with the collecting tubes of the parovarium ; below, they may some- 
times be traced to the vicinity of the urinary meatus. 
The organ of Giraldes in the male, is represented in the female, by a few scat- 
tered tubules, remnants also of the Wolffian body, which lie between the layers 
of the broad ligament, nearer to the uterus than the parovarium. 
The hydatid of Morgagni, a relic of the Mullerian duct, is usually found in 
the form of a small pediculated cyst, attached to one of the fimbriae of the Fal- 
lopian tube. It is lined with ciliated, columnar epithelium, and filled with a clear 
fluid. 
THE VAGINA. 
The vagina (“ sheath ”) (Fig. 898) is a distensible, musculo-membranous 
canal, which extends from the uterus to the vulva. It is the organ of copulation 
in the female, and in addition affords passage to the menstrual flow and the 
foetus. 
Location, Direction, and Dimensions.—It is situated in the median line of the 
pelvis, between the bladder and rectum. Running downward and forward, its 836 
THE ORGANS OF GENERATION. 
lower extremity makes with the horizontal plane an angle of 60° to 70°, open- 
ing posteriorly. The axis of the canal is not straight, but presents a posterior 
concavity, which fits a corresponding convexity of the rectal wall. The anterior 
vaginal wall measures two to two and a half inches in length; the posterior 
varies from two and a half to three and a half inches. Continuous above with 
DORSAL VEI N ' 
OF CLITORIS - 
PREPUCE OF— 
CLITORIS 
CLANS CLI- 
TORIDIS 
MEATUS^ 
Fig. 898—Sagittal section of the vagina and neighboring parts. (Testut.) 
the cervix, the vagina is further fixed in position by its connections with the 
bladder, rectum, vulva, and perineum. 
Conformation and Relations.—Above, where the vagina embraces the cervix, it 
is circular; below, at the vulvo-vaginal junction, it is elliptical, with the major 
axis antero-posterior. Between these points the anterior and posterior walls are 
in contact, thus reducing the canal to a mere fissure, which on transverse section 
is H-shaped. The vagina may therefore be divided for further description into 
two surfaces—the external or attached, and the internal or free; and two ex- 
tremities—the upper and the lower. 
The external surface presents two faces, an anterior and a posterior, and two 
lateral borders. The upper half of the anterior face is in relation with the 
bladder, the lower half with the urethra. The lower two-thirds of the latter is 
buried in the anterior vaginal wall, the upper third and the bladder are separated 
from this face by areolar tissue, continuous with the subperitoneal fascia. In 
this fascia the terminal segment of the ureter runs obliquely, to open into the 
bladder wall at a point one and a quarter inches below the level of the external 
os. (It must not be forgotten that in the female a portion of the base of the 
bladder rests against the anterior surface of the cervix.) The posterior face is 
covered above to a varying extent (usually about one inch) by the peritoneum as 
it dips into the cul-de-sac of Douglas. The middle portion rests against the 
rectum, from which it is separated by a continuation of subperitoneal fascia. 
Below, it is widely separated from the termination of the rectum by the triangu- 
lar perineal body. The lateral borders are in contact above with a small portion 
of the broad ligaments. In the upper third they are crossed obliquely by the 
ureters, and below this they are embraced by the anterior margins of the levatores 
ani muscles and the accompanying recto-vesical fascia. By the side of the upper 
half of each lateral border may sometimes be found a small tube, the continuation 
of the duct of Gartner. THE VULVA. 
837 
On the internal or mucous surface are two median longitudinal ridges, the 
columns of the vagina, situated one on the anterior, the other on the posterior 
wall. The latter is sometimes double. From these, numerous secondary ridges 
pass transversely outward to the lateral borders. Both the columns and secondary 
ridges are better marked in the lower portion of the vagina than above. After 
child-birth they diminish in prominence or entirely disappear. 
The superior extremity is attached to the circumference of the cervix reaching 
higher behind than in front. With the outer surface of the intra-vaginal seg- 
ment of the cervix it makes a circular pericervical trench, the fornix, which is 
deepest behind. The inferior extremity pierces the triangular ligament, and is the 
narrowest and least dilatable portion of the canal. 
Structure.—The vaginal wall, about one-sixth of an inch in thickness, con- 
sists of three coats—an outer of connective tissue, a middle of muscular tissue, 
and an inner of mucous membrane. The connective-tissue coat is a thin white 
fibrous structure, derived from the recto-vesical fascia. It contains a few smooth 
muscular fibres, and carries in its meshes a plexus of veins. The muscular coat, 
of unstriped fibres, may be divided into two layers, superficial and deep. The 
fibres of the superficial layer, longitudinal in arrangement, are continuous with 
the superficial muscular layer of the uterus. They are also continuous above 
with the utero-sacral ligaments, by means of which the vagina is attached to the 
sacrum. Below, some of the longitudinal fibres are inserted into the ischio- 
pubic rami, while others are lost on the triangular ligament and recto-vesical 
fascia. The deep layer is made up of circular fibres, which surround the canal. 
Near the vulvo-vaginal orifice these fibres are condensed into a ring of some 
strength, which forms an involuntary sphincter. The striated sphincter of the 
vagina is derived from the muscles of the perineum. The mucous coat, thrown 
into folds as already described, is covered with stratified epithelium, continuous 
witli that lining the vulva below and covering the cervix above. Its deep layer 
or corium is closely attached to the muscular tunic, no special submucosa inter- 
vening. The lower portion of this coat is studded with numerous conical or fili- 
form papillae. The upper portion presents a few closed follicles; otherwise the 
mucous membrane is entirely devoid of glands. 
Vessels and Nerves.—The arteries are all derived from the internal iliac or its 
branches. The vaginal artery, corresponding to the inferior vesical in the male, 
runs along the lateral borders of the vagina, supplying arteries to the anterior 
and posterior surfaces. A small vaginal branch from the uterine, and anastomos- 
ing branches from the remaining vesicals, middle hemorrhoidal, and internal pudic 
are also supplied. The veins, remarkable for their number and volume, direct 
themselves to the lateral borders, where they form the vaginal plexuses, one on 
either side. These communicate with the veins of the uterus, broad ligaments, 
bladder, rectum, and bulbs of the vagina, and finally empty through the uterine 
and vaginal trunks into the internal iliac vein. The lymphatics from the lower 
third of the vagina, joining with those from the vulva, empty into the superficial 
inguinal nodes; the remainder end in the internal iliac nodes. The nerves, 
derived from the hypogastric plexus, the fourth sacral, and the pudic, are dis- 
tributed to the mucous and muscular tunics. Their mode of termination is 
unknown. 
THE VULVA. 
The vulva or pudendum (Fig. 899), ovoid in outline, is bounded in front by 
the anterior abdominal wall, behind by the perineum, and laterally by the inner 
surfaces of the thighs. It includes the following parts ; (1) the mons Veneris, 
the labia raajora, and the labia minora (all derived from the integument); (2) 
between the labia a median space called the interlabial or vulval cleft; (3) an 
erectile apparatus ; (4) certain glandular structures. 838 
THE ORGANS OF GENERATION. 
The Mens Veneris. 
The mens Veneris is an elevation situated in front of the upper part of the 
pubic symphysis. Anteriorly and above, it merges into the integument covering 
the lower part of the abdomen, posteriorly it is continuous with the labia majora, 
laterally it is limited by the right and left inguinal folds. In structure the mons 
consists of modified skin, deeply pigmented, and covered with hair, beneath 
which is a collection of areolar and adipose tissue, intersected by a series of 
MONS VENERIS 
CLITORIS 
M EATUS 
URI N ARIUS 
Fig. 899.—Vulva of a virgin. The labia have been widely separated. (Testut.) 
elastic laminae. The latter take origin deeply from the linea alba and abdominal 
aponeurosis, and end by becoming attached to the deep surface of the skin.. 
The Labia Majora. 
The labia majora (“ greater lips”), two longitudinal folds of modified integu- 
ment, are continuous with the mons Veneris in front, and extend to within an 
inch of the anus behind. Each fold is about three inches in length, and presents 
for description two extremities, two surfaces, and two borders. The anterior 
extremities by their junction with the mons and with each other make up the 
anterior• commissure; the posterior, having become very thin, are united by the 
posterior commissure or fourchette (“ fork ”), which constitutes the thin, anterior 
edge of the perineum. The outer surface, separated from the corresponding 
thigh by the genito-crural fold, is deeply pigmented, covered with hair, and 
abundantly supplied with sudoriparous and sebaceous glands; the inner is in con- 
tact, when closed, in part with its fellow, in part with the labium minus of the 
same side. The skin, which lines this surface in the vicinity of the free border, 
resembles that on the outer surface; more deeply it is rosy, moist, studded with THE VULVA. 
839 
sebaceous follicles, and presents only rudimentary hairs. The superior or attached 
borders correspond to the ischio-pubic rami, with which they are connected by 
numerous fibrous bands. The inferior borders are free, and the fissure between 
them is called the rima (“crack”) pudendi. In infants, young women, and 
fleshy subjects the labia majora are firm, and directly applied one to the other; 
in the old, the thin, and those who have borne many children, they shrivel and 
gape apart. 
Beneath the integument of each labium majus there is found a tissue, resem- 
bling the dartos of the scrotum, but much thinner; beneath this a layer of 
adipose and connective tissue ; and still deeper an elastic, pear-shaped sac, called 
Broca’s pouch. This contains connective tissue and fat; and its mouth, applied 
to the external abdominal ring, may sometimes receive the termination of the 
canal of Nuck. Morphologically the labia majora correspond to the scrotum in 
the male. 
The Labia Minora. 
The labia minora (“ smaller lips ”), or nymphce, are two smaller longitudinal 
folds, placed within the labia majora, and running from the clitoris downward 
and backward for about one and one-half inches. They also present two sur- 
faces, two borders and two extremities. The external surfaces are in contact 
with the labia majora, the internal with each other. The superior borders are 
attached, the inferior, often crenated, are free. The anterior extremities 
divide, each into two bands. The superior of these unite above the dorsum of 
the clitoris to form its prepuce; the inferior, uniting beneath the clitoris to which 
they are attached, form its frenum. Posteriorly each labium terminates opposite 
to or a little behind the middle of the rima pudendi. Rarely it is continuous 
farther backward, and is joined to its fellow by a slender transverse fold, placed 
on the anterior edge of the posterior commissure. This fold then becomes the 
fourchette. The nymphse are composed of modified skin, beneath which is 
a connective tissue, rich in elastic and smooth muscular fibres, but containing 
no fat. In the young, where they are protected by the labia majora, they are rosy 
in color and moist, approaching in character the mucous membranes; when they 
project beyond the labia majora, however, they become dry and deeply pigmented. 
Their surfaces are free from hairs and sudoriparous glands, but are abundantly 
supplied with sebaceous glands, which secrete a thick, white substance, akin to 
the preputial smegma, and with papillae, which contain nerves ending in tactile 
corpuscles. 
The Interlabial Space. 
The interlabial space or vulval cleft is bounded on either side by the labia 
majora and minora, in front by the clitoris, and behind by the posterior commis- 
sure. It receives the orifice of the vagina and the external opening of the 
urethra, becoming therefore the common uro-genital opening. Ordinarily, .the 
tissues falling together, the space is obliterated, becoming merely a fissure ; but, 
when the labia are drawn apart, it becomes broad, shallow, and elliptical in out- 
line. Superficially, it is lined with modified skin, deeply with mucous membrane, 
which merges into that of the vagina and urethra. The line of demarcation 
between the skin and mucous membrane runs from beneath the prepuce of the 
clitoris backward along the inner surface and attached border of the labium 
minus to the outer aspect of the hymen (Hart). In the floor of the interla- 
bial space from before backward may be seen the vestibule, meatus urinarius, 
orifice of the vagina, hymen, and fossa navicularis. 
The Vestibule is a shallow triangular space, bounded laterally by the nymphse, 
and behind by the orifice of the vagina. Its apex, directed forward, coincides 
with the clitoris. 
The Meatus Urinarius, the external opening of the urethra, is situated in the 
median line, at the back part of the vestibule, about an inch behind the clitoris,. 840 
THE ORGANS OF GENERATION. 
and just in front of the vagina. Directly behind it there is an elevation of mucous 
membrane, the vaginal tubercle, which serves as a guide to the introduction of 
a catheter. 
The Inferior Orifice of the Vagina (■introitus vaginae), when the hymen has 
been removed, is elliptical in outline. Its diameters are much greater in women 
who have borne children than in the nulliparous. 
The Hymen (“ a membrane”) (Fig. 900) is placed at the vulvo-vaginal junction, 
narrowing to a greater or less degree the inferior vaginal orifice. It is composed 
CRESCENTJC 
FRINGED 
Fig. 900.—Varieties of hymen. (Testut after Roze.) 
BILABIAL 
BI PERFORATE 
CRIBRIFORM 
of a double fold of raucous membrane, between the layers of which is found 
connective tissue, rich in elastic fibres. In shape it varies widely, the commonest 
forms being the falciform and the annular. In the former the hymen is semi- 
lunar in outline, with the concavity looking forward; in the latter a complete 
ring, usually widest posteriorly, surrounds the opening. Sometimes it forms 
a complete septum (imperforate hymen) or has many small openings (cribriform). 
The hymen is usually torn during the first coition, but may, when very elastic, 
escape rupture. After parturition there remain of if only some slight rounded 
elevations, the carunculce myrtiformes (“ little masses of flesh like myrtle-berries ”), 
which occupy the site of its attached border. 
The navicular fossa is that portion of the interlabial space, which lies behind 
the entrance to the vagina. It is bounded superficially by the fourchette, deeply 
by the superficial surface of the hymen. 
The erectile organs belonging to the vulva are the clitoris and the bulbs of 
the vagina. 
The Clitoris, about one inch in length, is situated at the apex of the vestibule, 
between the anterior extremities of the nymphse. It is the homologue of the 
penis, but has no corpus spongiosum, and no urethra. The two corpora cavernosa, 
of which it is mainly composed, are similar in minute structure to those of the 
male. Diverging behind, they constitute the crura, which are attached to the 
ischio-pubic rami superficial to the triangular ligament, and covered by the ischio- 
cavernosi (erectores clitoridis) muscles. In front the corpora cavernosa unite to 
form the body of the clitoris, the septum pectiniforme between them being 
imperfect. Their united distal extremities are surmounted by a glans, composed 
of very sensitive, spongy, erectile tissue. The clitoris has a prepuce and a 
frenum, both derived from the nymphse, and is also provided with a suspensory 
ligament. It is supplied with helicine arteries and numerous anastomosing veins, 
Erectile Organs. THE VULVA. 
841 
agrees in structure with the erectile tissues described elsewhere, and is capable of 
erection. 
The Bulbi Vestibuli (Fig. 901), or bulbs of the vagina, are two pyriform masses 
of erectile tissue, made up chiefly of a plexus of veins, enclosed in a thin, fibrous 
tunic. They are about an inch in length, and are placed one on either side of the 
uro-genital space, a little above the level of the nymphse. Together they repre- 
sent the bulb of the corpus spongiosum in the male. They each present 
two surfaces, two borders, and two extremities. The inner surfaces, covered by 
mucous membrane, are in close relation with the orifices of the urethra and 
vagina; the outer are covered by the bulbo-cavernosi muscles (acceleratores urinse 
in the male), which here become the constrictors of the vagina. The upper 
borders are attached to the superficial layer of the triangular ligament, while the 
lower correspond with the attached borders of the nymphse. The posterior 
extremities are rounded, and reach to the navicular fossa. The anterior pointed 
extremity of each is continued forward by means of a narrower plexus, the pars 
intermedia, which communicates with its fellow beneath the clitoris. The pars 
intermedia is homologous to that portion of the corpus spongiosum, which lies 
between the bulb and the glans. It receives veins from the nymphse, and serves 
to connect the bulbs with the veins of the glans clitoridis and corpora cavernosa. 
When engorged the bulbi vestibuli narrow the vaginal orifice. 
Glands. 
In connection with the vulva are found : (1) the vulvo-vaginal glands; (2) 
the urethral and peri-urethral glands. 
The Vulvo-vaginal Glands, or glands of Bartholin (Fig. 901), two in number, are 
situated one on either side of the vagina posteriorly, between the layers of the triangu- 
lar ligament. They are round 
or oval in outline, measuring 
about half an inch in their 
longest diameter. Their 
ducts run forward and in- 
ward to open into the vulval 
canal, one on either side, 
in the groove between the 
hymen and labia minora. 
They are racemose, mucous 
glands, homologues of the 
glands of Cowper in the 
male, and their secretion 
lubricates the vulval canal. 
BULB OF_ 
VAGINA 
VULVO-VAGINAL 
GLAND 
The Urethral Glands, 
found chiefly beneath the 
lateral walls and floor of 
the urethra, vary in struct- 
ure from simple inversions 
of the mucous membrane 
to racemose glands. Their 
openings are arranged in 
rows parallel with the long axis of the canal. They secrete mucus, and corre- 
spond morphologically with the prostatic glandular structure. Other glands 
found in the vestibule near to the urethra are designated peri-urethral or glandulce 
vestibulares minores, the latter to distinguish them from the glandulce vestihulares 
majores or glands of Bartholin. 
Vessels and Nerves.—Arteries.—The superficial portions of the vulva are 
supplied by branches of the external and internal pudics; the deeper, by branches 
of the internal pudics alone. The clitoris and bulbi vestibuli receive branches 
Fig. 901.—Vulvo-vaginal gland. The broken line indicates the 
limits of the bulb of the vagina. (Testut.) 842 
THE ORGANS OF GENERATION. 
from the internal pudics, corresponding in name to similar branches in the male. 
The veins for the most part end in trunks, which accompany the arteries. Those 
of the labium majus communicate freely with the veins of the round ligament at 
its distal extremity, while the bulbi vestibnli communicate with the vaginal 
plexuses, the dorsal vein of the clitoris, the veins of the corpora cavernosa, and 
the obturator veins. The lymphatics accompany the veins and empty into the 
superficial inguinal nodes. 
Nerves.—Sympathetic nerves derived from the pelvic or inferior hypogastric 
plexus accompany the arteries. In addition spinal branches are supplied by the 
genito-crural, inferior pudendal, and internal pudic. In the nymphaj and glans 
clitoridis they end in the tactile corpuscles of Pacini and Meissner, and on the 
glans alone in the so-called genital corpuscles. 
THE MUSCLES OF THE FEMALE PERINEUM. 
The muscles of the female perineum (Fig. 902) are the homolognes of those 
in the male. 
Fig. 902.—Muscles of the female perineum. (Testut.) 
The sphincter ani externus and coccygeus are identical in the two sexes. 
The transversi perinei and ischio-cavernosi differ from their male counterparts 
only in being smaller. The ischio-eavernosus is more frequently called the 
erector clitoridis, as it sustains the same relations to the clitoris that its enlarged 
masculine fac-simile does to the penis. 
In the levator ani the anterior portion courses at the side of the vagina, and 
the pair of muscles probably produce some constriction of the lumen of the tube. 
The bulbo-cavernosi are more commonly called the sphincter vaginae or com- 
pressor vaginae. They are smaller than in the male, and, instead of being united 
by a median raphe, are separated, and include in their grasp the opening of the 
vagina and the bulbs of the vestibule. They are inserted into the cavernous 
bodies of the clitoris. 
The constrictor urethrae, or transversus perinei profundus, is mainly composed 
of unstriped muscular tissue. Its origin, as in the male, is from the ischio-pubic 
rami. The smaller anterior portion stretches across the subpubic arch in front THE MAMMARY GLANDS. 
843 
of the urethra. The larger, posterior portion is lost rnesially in the muscular 
wall of the vagina. 
The two mammary glands, mammce, or breasts, are accessory organs of genera- 
tion, their secretion, the milk, serving to sustain the infant until it is capable of 
deriving its nourishment from other sources. Philosophically considered, each 
mamma is a collection of sebaceous glands, greatly enlarged, and extending far 
THE MAMMARY GLANDS. 
CLAVICLE 
_FIRST 
RIB 
PECTORAI-IS MAJOR- 
SKIN - 
SECOND 
RIB 
PECTORALIS 
MINOR 
INTERCOSTALES 
FIBROUS SEPTUM 
SHEATH OF PEC- 
TORALIS MAJOR 
GLAND SUBSTANCE 
'THIRD RIB 
ADIPOSE TISSUE 
•AREOLAR TISSUE 
SUPERFICIAL 
FASCIA 
AREOLA- 
FOURTH RIB 
LUNG 
NIPPLE- 
ADIPOSE TISSUE 
HORIZONTAL PLANE 
OF NIPPLE 
FIFTH RIB 
SIXTH RIB 
Fig. 903.—Right breast in sagittal section, inner surface of outer segment. (Testut.) 
into the subcutaneous region, which here is vastly deeper than elsewhere. The 
secretion of the sebaceous glands is oily, and that of their prodigious congeners is 
of the same character, though in the one case the fluid is devoted to purposes of 
lubrication, in the other to nutritive uses. 
Each breast is approximately hemispherical, and a little below the centre of 
its convexity presents a mammilla (nipple, teat, dug), usually shaped like a trun- 
cated cone, half an inch long, pointing forward, upward, and outward, and set in 
the middle of a circular area of darker skin, the areola. 
The breast covers a nearly circular space, mostly in front of the pectoralis 
major, extending from the second to the sixth rib, and from the sternum to the 
border of the armpit. The location of the nipple is usually given as at the level 
of the fourth rib ; but its position is dependent upon various circumstances, such 
as age, pregnancy, lactation, corpulence, firmness of tissues, race, attitude of body, 
(not to mention numerous diseases), so that it becomes one of the least trust- 
worthy of landmarks. 844 
THE ORGANS OF GENERATION. 
The weight of the breast is usually above five ounces in the inactive condition. 
The secreting structure of the breast consists of from ten to twenty separate 
lobes, each of which is a compound, racemose, acinous gland. Each of these 
AREOLA 
LARGE 
SEBACEOUS 
CONCENTRIC 
RIDGES 
GLANDS 
SKIN OF 
BREAST 
Fig. 904.—Nipple and areola of a virgin. (Testut.) 
glands is made up of lobules, which are colonies of alveoli, and has its own ulti- 
mate excretory duct, called galactophorous or lactiferous (“milk-carrying”). The 
ducts from all parts of the breast converge toward the nipple, and, when they 
reach the areola, each dilates into a sinus or ampulla, half an inch long and half as 
wide, which serves as a little reservoir for the milk. Beyond this the duct is 
reduced to a small calibre, and terminates at the summit of the nipple in a con- 
tracted orifice. 
The alveoli and ducts are lined with a simple epithelium, partly flattened and 
partly cuboidal or cylindrical. The wall of the ducts is composed of mixed white 
and yellow fibrous tissues, arranged in longi- 
tudinal and circular bundles. 
SECONDARY AREOLA 
The proper gland-substance is supported 
on a framework of the fibrous tissues, which 
also form an enclosing capsule for the organ. 
This capsule sends processes inward between 
the lobes and lobules, and processes outward 
to the deep surface of the skin. Among the 
masses of glandular material are many nodules 
of adipose tissue, which are of greatest size 
near the convex surface, though some con- 
siderable collections are found at the flat, hind 
surface of the gland. No fat, however, appears 
beneath the nipple and areola. 
The mammilla is composed of skin, pecu- 
liarly modified, and containing the terminal 
portion of the milk-ducts. It is dark, wrinkled, 
beset with papillae, which are extremely sensi- 
tive, but has no sweat-glands or hairs. It is very vascular, and among the ves- 
sels are many fibres of unstriped muscular tissue—an arrangement which gives it 
the properties of erectile tissue, so that under the stimulus of contact or even 
emotion, it may swell and become rigid. Its summit presents the orifices of the 
many lactiferous ducts. 
The areola resembles the nipple in color and in structure, being pigmented 
and somewhat erectile. In addition it is dotted over with little, roundish pro- 
jections, due to large, sebaceous glands in the skin, in connection with each of 
which is a delicate, minute hair. 
Fig. 905.—Nipple and areolse of a preg- 
nant woman. (Testut.) 
Modifications.—ln women who have not become pregnant the glandular tissue THE MAMMARY GLANDS. 
845 
is but slightly developed (even though the breast may be plump and firm), and 
the nipple and areola are pink. But as early as the second month of pregnancy 
the color of these parts deepens, and may become dark brown, and the secreting 
structure begins to develop. A secondary areola, much fainter than the primary, 
may be observed encircling it. The breasts become very large and heavy during 
the period of nursing, but shrink when lactation is completed, and simultaneously 
the added pigment mostly disappears from the areola and nipple ; but the delicate 
rosy hue of the -virgin state is never restored. After the menopause the gland 
shrivels into a thin disc, incapable of function ; but this diminution may not be 
outwardly manifest in the corpulent on account of the great accumulation of fat. 
During menstruation the breasts may swell, owing to sympathetic congestion. In 
some women the nipple does not project beyond the surface of the breast, and in 
certain cases it is even retracted, a dimple marking its situation. In the male the 
mammary gland is rudimentary and minute. The nipple is small, and the areola 
presents a growth of rather strong hairs. 
Very rarely women have supernumerary mammae, thus imitating many of the 
lower animals. One case is recorded in which a woman had eight supplementary 
breasts, in addition to the usual pair. On the other hand there may be entire 
failure of development beyond the rudimentary condition. Very phenomenally 
the male breast ceases to be a mere rudiment, and becomes capable of furnishing 
milk. 
Vessels and Nerves.—The arteries of the mamma are branches of the axillary, 
internal mammary, and intercostals. The veins correspond. The lymphatics run 
to the axillary nodes (primarily to the pectoral group, secondarily to the others) 
and to the sternal. The nerves are chiefly intercostal. RELATIONAL ANATOMY 
F. H. GERRISH. 
IN the chapters on Systematic Anatomy much has been presented concerning 
the relations existing between the parts and organs described. It would 
doubtless be useful to have all of these statements gathered into a single section, 
but the prescribed limits of this work forbid such a course. The purpose of this 
chapter is to introduce certain matters which did not conveniently fall into line 
with any of the topics of Systematic Anatomy, to emphasize some of the most 
important points which have previously been made, and to show by methods, 
hitherto little employed, facts of interest and value concerning the structure 
of the body. 
The chapter will be divided into three parts, each of which will be devoted 
to a different method of studying Relational Anatomy. In the first part will be 
presented a series of plane sections of the trunk and limbs; in the second part, 
reproductions of photographs of the surface; and in the third part, skiagraphs 
of every portion of the body, whose osseous structure can be profitably studied 
by the aid of the so-called X-rays. 
However full may be the descriptions in such a chapter, its chief and essential 
value will always reside in the pictures; and those that are here given are so 
clear, and tell their own story so distinctly, that only a few words of introduction 
for each are needed, and the descriptive text can, therefore, be reduced to a 
minimum. 
It is recommended that each of these pictures be studied in connection with 
everything else in the book which bears upon the subjects involved. For example, 
in considering the region of the forearm, the systematic anatomy of the bones, 
muscles, fasciae, arteries, veins, lymphatics, and nerves of the part should be 
studied anew; next, the plane section should be examined with care, and the 
location of every organ fixed in mind; then the various photographs of the 
surface of the part should receive attention ; and, finally, the corresponding 
skiagraphs should be regarded. By the combination of all these methods the 
student will be able to obtain all of the anatomical information of the locality 
that a text-book can afford. 
I. PLANE SECTIONS. 
In each of these pictures the upper surface of the lower segment resulting 
from the section is shown—in other words, the upper segment has been removed, 
and we look down upon the specimen. In the case of the sections of the limbs 
we may profitably imagine them to be the stumps of amputations of the opposite 
limbs at the same level—that is, they present such a view as would be given by 
the cut surface of the proximal part on the other side. 
In the representations of sections of the trunk much lack of bilateral sym- 
metry will be found, not only as concerns details, but also in the outlines of the 
figure. This is due to several causes. Perfect symmetry of contour on the 
opposite sides is practically unknown; the corresponding parts are rarely exactly 
847 848 
BELA TIONAL ANA TOMY. 
Fig. 906.—Horizontal section through the lowest part of the body of the seventh cervical vertebra, close to junction of neck and trunk. (After Braune.) 
The upper cartilage of the trachea is cut, and on the front of it is a small part of the lower portion of the cricoid cartilage. The thyroid vessels are seen in and near the 
thyroid gland. The head of the first rib appears on the right side of the vertebral body. The transverse processes belong to the first thoracic vertebra. The muscle on the 
front of the body of the vertebra is the longus colli. The ventral, unlabelled part of the mass of scaleni, is the scalenus anterior. In front of the vertebral artery is the 
vertebral vein, and in front of the latter, on the right side, is the inferior cervical ganglion of the sympathetic. On each side, between the trachea and oesophagus, is the 
recurrent laryngeal nerve. The spinal accessory nerve is seen in the right trapezius, close to the clavicle ; on the left side it is not drawn. On the right side the section has 
opened the acromio-clavicular joint; on the left it passes below it. The serratus magnus does not appear on the left. The brachial plexus is seen in three parts, ranged in 
a ventre-lateral line from the spinal cord. PLANE SECTIONS. 
849 
Pig. 907.—Horizontal section through the body of the third thoracic vertebra. (After Braune.) 
.. tern(-:,'clei5lo;mastoif-?<;lls'. V. A., vertebral artery. BIC., tendon of long head of biceps. The cut passes through the upper border of the sternum, the spine of 
tne second thoracic vertebra, and the head of each humerus. Between the trachea and oesophagus is the left recurrent laryngeal nerve. Observe that the trachea is much 
further from the ventral surface than in Fig. 906. The brachio-cephalic artery is median, and obliquely at its left are the left carotid and left subclavian. The brachial 
plexus is in close relation to the subclavian artery. The apices of the lungs have been cut off. 850 
RELATIONAL ANATOMY. 
Fig. 908,—Horizontal section through the body of the sixth thoracic vertebra. (After Braune.) 
The cut passes through the spine of the fifth thoracic vertebra, the body of the sternum, the humerus just below the tuberosities, and the scapula near the lower angle. 
The axilla, with its vessels and nerves, is opened. The lungs show their great fissure. The uppermost part of the heart has been removed, and we look down upon the pul- 
monary and aortic valves. Observe the pericardium and pleura; the descending aorta at the left of the vertebra; the thoracic duct (here double); and the pnepmogastric 
nerves. PLANE SECTIONS. 
851 
Fig. 909.—Horizontal section through the upper part of the body of the eighth thoracic vertebra. (After Braune.) 
has been cut so obliquely that the ventricular walls appear thicker than they are. The lungs present large surfaces, and both fissures 
upperVimbsno Hunger are^seen6 116 pericardluln’ Pleurse> an(i the position of the aorta and oesophagus. The section being below the axilla, the 852 
BELA TIONA L ANA TO MY, 
Fig. 910.—Horizontal section through the lower part of the body and arch of the eleventh thoracic vertebra. (After Braune.) 
The diaphragm encircles the abdominal cavity, having peritoneum on its inner surface and the pie tine on its outer. Observe the great space 
occupied by the liver, the relations of the stomach and spleen, the position of the right suprarenal body. PLANE SECTIONS. 
853 
Fig. 911—Horizontal section through the middle of the first lumbar vertebra. (After Braune.) 
The twelfth rib appears on the right, but the section is below it on the left. Between the vena cava and the pancreas is the common bile' duct. 
The lowest parts of pleura, liver, spleen, and stomach are seen. The pancreas is cut in its entire length. The right kidney is cut near its upper end, 
the left in the middle. 854 
RELATIONAL ANATOMY. 
EXTERNAL ILIAC ARTERY 
ANTERIOR CRURAL NERVE 
EXTERNAL ILIAC VEIN 
VAGIN/E 
|Tn~“FEMORIS 
SCIATIC NERVE 
INFERIOR GLUTEAL ARTERY1 
Fig. 912.—Horizontal section three inches below the sacral promontory. (Testut.) The unlabelled parts in 
front of and at the right of the bladder are coils of small intestine. 
INTERNAL PUDIC ARTERY 
Pro. 913.—Horizontal section at middle of right arm—upper surface of lower segment. B. V., basilic vein ; 
CEPH. V., cephalic vein; I. C. N., internal cutaneous nerve; I. P. A., inferior profunda artery ; M. C. N., mus- 
culo-cutaneous nerve ; M. N., median nerve; M. S. N., musculo-spiral nerve •. S. P. A.,superior profunda artery ; 
U. N., ulnar nerve. (After Braune.) PLANE SECTIONS. 
855 
mated; and, finally, it is almost impossible to carry the saw with absolute pre- 
cision through all parts of the plane intended. 
The subjects from which these sections were taken were particularly muscular 
young men, and the appearances differ considerably from those observed in poorly 
developed or emaciated people. This is very marked in the case of the shoulders, 
whose high appearance is at least partly due to the very pronounced muscularity. 
RADIAL ARTERY \ 
TENDON OF EXTENSOR CARPI 
J RADIALIS LONGUS 
PALMARIS 
LONGUSy 
MEDIAN NERVE- 
ULNAR \ 
ARTERY -i 
ULNAR NERVE \ 
Fig. 914.—Transverse section through the middle of the right forearm, in the position of semipronation, 
(After Braune.) 
In all of these drawings conventionalized shading is employed for the sake of 
clearness, and thus a somewhat diagrammatic effect is produced. But the pur- 
pose is to show relations, and not composition. 
The serous and synovial (virtual) cavities are represented by heavy black 
lines. Only by some such exaggerated method can they be made distinct in 
plane sections. 
Vessels and other tubes, when cut obliquely, present peculiar outlines; and 
these are more marked the more nearly the section is in line with the long axis 
of the cylinder. 
In the cut surfaces of many muscles will be seen tendons embedded in their 
substance. This fact is referred to in the general considerations concerning 
myology, but was purposely omitted from the description of the individual 
muscles. 
In some of the pictures which have substantially bilateral symmetry the parts 
are labelled on one side only. 
The important parts are, as a rule, labelled; but in some cases this method 
was impracticable, and in these the legend will direct attention to the unlabelled 
objects. 856 
RELATIONAL ANATOMY. 
FEMORAL ARTERY 
FEMORAL VEIN. 
ANTERIOR CRURAL NERVE 
PROFUNDA ARTERY 
BRANCHES OF 
OBTURATOR NERVE\ 
SAPHENOUS VEIN 
EXTERNAL CUTANEOUS 
NERVE 
Fig. 915.—Transverse section of the thigh below the trochanter minor. (After Braune.) SURFACE ANATOMY. 
857 
POSTERIOR 
TIBIAL / 
artery/ 
rNARTE.RY 
PLANTARIS\ 
Fig. 916-—Transverse section at the middle of the leg, (After Braune.) In front of the interosseous mem- 
brane are the anterior tibial vessels and nerve ; in front of the soleus, the posterior tibial vessels and nerve; 
and close to the fibula, the peroneal vessels. 
11. SURFACE ANATOMY. 
The subject of the photographs, of which the series of pictures in this section 
are reproductions, was a young athlete of well-balanced development. It would 
be easy to procure representations of a man with much larger muscles, but they 
would be less useful in the illustration of normal anatomy. The main purpose 
of these engravings is to show the relations of structures, especially muscles, to 
the surface. The most of them are accompanied by keys, which more than sup- 
ply the place of verbal description; in the remainder the principal features are 
sufficiently apparent without explanation other than occurs in the legend. 
Every student is earnestly advised to study surface anatomy upon the living 
model. Each can use his chum for this purpose, if he will reciprocate such favors 
as he receives ; and many things he can learn from his own person, particularly 
well in front of a large mirror. He should carry his studies in this direction 
much further than is attempted in this series of pictures, and in this effort he 
will derive all the help that he needs from the numerous cuts which embellish 
the pages devoted to descriptive anatomy. 858 
JR EL A TIONA L ANA TOM Y. 
Fig. 918.—Key to Fig. 917. SURFACE ANATOMY. 
859 
Fig. 920.—Key to Fig. 919. 860 
RELATIONAL ANATOMY. 
Fig. 922.—Key to Fig. 921. SURFACE ANATOMY. 
861 
Fig. 924.—Key to Fig. 923. 862 
RELATIONAL ANATOMY. 
Fig. 925.—Abduction of the arm with flexion of the forearm and digits. SURFACE ANATOMY. 
863 
GLUTEUS 
MEDIUS 
■ADDUCTOR 
MAGNUS 
RECTUS 
.LIGAMENTUM 
PATELLA 
SOLEUS. 
PERONEUS 
LONGUS— 
.GASTROCNEMIUS 
SOLEUS 
JNNER MALLEOLUS 
OUTER MALLEOLUS. 
-EXTENSOR PROPRIUS 
HALLUCIS 
PERONEUS TERTIUS 
Pig. 926.—The right lower limb, front view. 
Pig. 927.—Key to Fig. 926. 864 
BELA TIONA L ANA TO MY. 
GLUTEUS 
MEDIUS 
GLUTEUS 
MAXIMUS 
GRACILIS 1 
BICEPS 
POPL. 
SPACE 
SARTORIUS _ 
GASTROCNEMIUS 
,SOLEUS 
SOLEUS— 
PERONEUS LONGUS 
FLEXOR LONGUS 
DIGITORUM 
FLEXOR LONGUS 
HALLUCIS 
INTERNAL 
MALLEOLUS- 
-EXTERNAL 
MALLEOLUS 
TIBIALIS 
POSTERIOR- 
-PERONEUS BREVIS 
Fig. 928.—The right lower limb, rear view. 
Fig. 929.—Key to Fig. 928. SURFACE ANATOMY. 
865 
GLUTEUS 
MEDIUS 
GLUTEUS 
MAXIMUS 
VASTUS 
EXTERNUS 
SEMIMEMBRA- 
NOSUS— 
PATELLA 
ILIO-TIBIAL BAND 
HEAD OF FIBULA 
HEAD OF TIBIA 
.LIGAMENTUM PATELLA 
PERONEUS BREVIS 
.EXTENSOR PROPRtUS HALLUCIS 
-PERONEUS TERTiUS 
, EXTENSOR BREVIS 
DIGITORUM 
Fig. 930.—The right lower limb, external lateral view, 
Fig. 931.—Key to Fig. 930. 866 
RELATIONAL ANATOMY. 
ADD. 
\ LONG. 
ADD. 
MAG./ 
VASTUS 
INTERNUS 
/ INNER 
t^ONDYLi 
TIBIALIS 
ANTERIOR- 
GASTROC- 
NEMIUS 
FLEXOR LONGUS 
_HALLUCIS 
TIBIALIS ANTERIOR- 
TIBIALIS 
- ANTERIOR 
EXTENSOR PROPRIUS / 
HALLUCIS —7^/ 
Fig. 932.—The right lower limb, internal lateral view. 
Fig. 933—Key to Fig. 932. SURFACE ANATOMY. 
867 
Fig. 934.—Comparison of axilla; with the arm abducted and with the arm vertical. The latter attitude is 
seen to flatten and nearly obliterate the'pit. 868 
BELA TIONA L ANA TOMY. 
Fin. 935.—Comparison of shoulders and arms in different attitudes. The sliding outward of the scapula 
when the arm is raised is very marked. 
Fig. 93R. The platysma muscle in contraction. The front and rear fasciculi can be brought out more prom- 
inently" by forcible protrusion of the chin; but strong pressure of the forehead against a resisting object dis- 
plays the whole muscle more evenly. SURFACE ANATOMY. 
869 
Fig. 937.—This figure and the next one are de- 
signed to show the capacity of the body for rotation. 
The feet point in one direction, the face exactly op- 
posite. This was accomplished without previous 
practice. 
Fig. 938.—T0 be compared with Fig. 937. The 
thighs and feet are held pointing away from the 
spectator, and the sitter has turned to face the camera 
as_squarely as possible. If the effect obtained by 
this method be subtracted from that in Fig. 937, the 
amount of rotation below the movable vertebrae will 
be ascertained. 870 
RELATIONAL ANATOMY. 
J3REGM A 
GLABELLA^ 
NASIOHB 
■OB ELION 
[LAMBDA 
ANTERIOR NASAL, 
SPINE 
PROSTHIONJ 
ni n i on 
GNATH ION! 
GO N lON 
Fig. 939. (Extra-serial.)— The relations of the principal fissures and of the lower borders of the cerebral 
hemisphere to the surface of the skull. The fissures and borders are not labelled, as the Sylvian, central, and 
parieto-occipital fissures cannot be mistaken. The inferior line does not show the lowest level reached by the 
temporal and occipital lobes, but the lowest parts of them that come close to the skull. NORMAL SKIAGRAPHS. 
871 
111. NORMAL SKIAGRAPHS. 
A little more than three years ago it was discovered that certain rays of light 
have the power of passing through substances which to ordinary rays are impene- 
trable. On account of their undetermined character they were called originally 
by the name of the letter which in algebraic formulae indicates the unknown ; 
and the title X-rays is still as well deserved as in the beginning. They are also 
called, from their discoverer, Rontgen rays. 
The degrees of perviousness to these rays presented by different substances 
vary widely. Wood offers but little obstruction to their passage, glass cuts them 
off. Of the tissues of the body those containing lime salts stop the rays most 
completely ; cartilage permits their passage with great readiness; and the other 
textures stand at various points between these extremes. The result is, that if a 
part of the body be suitably placed between an apparatus which generates these 
rays and a properly sensitized plate, shadows of the intervening structures which 
interfere with the rays will be cast upon the plate, and fixed there with different 
degrees of intensity. The plate is a negative from which photographic prints can 
be made, and these are called skiagraphs (“shadow-writings”). 
That this wonderful discovery could be turned to great advantage in surgery 
was immediately perceived, and its usefulness in the diagnosis of fractures and 
dislocations, and in the detection of certain foreign bodies, especially those which 
are metallic, in the tissues or cavities, has been abundantly demonstrated. 
In order, however, to appreciate the existence and degree of the abnormal it 
is important to become familiar with the normal. Consequently, there are here 
presented skiagraphs of different portions of the body, pictures from more than 
one point of view being given wherever it seemed necessary to elucidate relational 
anatomy by this novel means. No skiagraph of the head is included, as it has 
not thus far been found practicable to determine anything useful anatomically 
from those which have been made. 
In studying skiagraphs several considerations should be borne in mind, among 
which the following are prominent: 
A more dense portion of a given tissue throws a deeper shadow than a less 
dense portion of the same. Thus, the expanded extremities of bones, largely 
composed of cancellated tissue, show lighter than the shafts, where the tissue is 
compact. 
The thickness of the part influences the depth of the shadow. Thus, in a 
long bone the compact structure of the shaft gives a deeper shade at the sides 
than in the centre, not because the tissue is denser, but because, from a given 
point, the rays pass through a greater amount of it, (See the metacarpal bones 
in Fig. 944.) 
An accumulation of tissue of the same or different kinds deepens the shadow. 
(See the condylar region in Fig. 943.) 
The overlapping of one part by another causes a deepening of the shadow. 
(See the head of the radius and the coronoid process of the ulna in Fig. 943.) 
As cartilage gives a ready passage to the rays, the ends of bones in movable 
joints seem separated by unoccupied spaces, except when a convexity of one bone 
is received into a concavity of another of sufficient depth to produce apparent 
continuity of osseous tissue; and epiphyses, not yet united to their diaphyses, 
are held off from them by obvious gaps. 
The outline of a shadow does not necessarily represent the true size or shape 
of certain parts. For example, the outlines of the skiagraph of the heart, which 
is in constant active motion, and of the liver, which is in incessant passive motion, 
include greater areas than do the real shadows at any one moment of time. When 
such parts can be skiagraphed instantaneously, this objection will be removed. 872 
RELATIONAL ANATOMY. 
Fig. 940.—The trunk, upper part. From a man of 28 years. The shadow of the heart and great vessels has an obscure outline, owing to their being in incessant motion The vertebras 
do not show plainly ; they would be seen much more distinctly in a person in his teens. The lungs interfere very slightly with the passage of the rays. NORMAL SKIAGRAPHS. 
Fig. 941.—The shoulder. From a man of 28 years. Observe the vertebral border of the scapula, faint because thin ; its heavy, 
thick, axillary border; the coracoid process ; the spine and acromion ; the clavicle; the cartilaginous gap at the acromio-clavicular 
joint; the upper end of the humerus; the ribs; the vertebral column ; and the intervertebral discs in the upper thoracic region. 874 
RE LA TIONA L ANA TOM Y. 
Pig. 942.—The elbow-joint and adjacent parts, ventro-dorsal view. From a man of 28 years. NORMA L SKI A GRAPHS. 
875 
Fig. 943.—The arm and forearm, side view. From a man of 28 years. The forearm is in semipronation. 
Observe the dense shadows where the head of the radius and coronoid process of the ulna overlap, and where 
the condyles are most prominent. 876 
BELA TIONA L ANA TOMY. 
Fig. 944—The hand. From a man of 53 years. Observe the sesamoid bone at the metacarpo-phalangeal 
joint of the thumb; the different thickness of the folds of skin in the web between the thumb and index- 
finger; and the faint shadow of the nails, plainest in the ring-finger. NORMAL SKIAGRAPHS. 
877 
Fig. 945.—The lower part of the trunk and the upper part of the thighs. From a hoy of 15 years. Observe 
the sacral foramina and intervertebral spaces. The hip-bones show with great distinctness. The penis is 
turned to one side. 878 
RELATIONAL ANATOMY. 
Fig. 946.—The hip-joint and surrounding parts. From the same skiagraph as Fig. 945. The interference of 
overlapping parts of hone, the thinness of the ilium in the fossa, and the apparent deficiency between the 
caput femoris and the acetabulum deserve attention. NORMAL SKIAGRAPHS. 
879 
Fig. 947.—The knee, ventrodorsal view. From a man of 28 years. The tibia and fibula overlap. 880 
RELATIONAL ANATOMY. 
Fig. 948.—The knee, side view. From a man of 28 years. Observe that the patella touches the femur above, 
but seems to stand away from it below. The ligamentum patellae makes a slight appearance. NORM A L SKI A GBA PHS. 
881 
prr 040 _The foot in full extension, dorso-plantar view. From a man of 21 years The first and fifth toes 
are deformedbythe wearing of pointed shoes'. The deep shadow about the ankle-joint is due to the great 
thickness of the bony mass. 882 
RELATIONAL ANATOMY. 
Fig. 950.—The foot, side view. From the same man as Fig. 949. Every hone is more or less overlapped by 
some other. PRACTICAL ANATOMY 
By F. H. GERRISH. 
IT is the purpose of this final chapter to give directions concerning the conduct 
of dissections. 
Preparatory Study.—There is but little profit in attempting a dissection until 
one has become familiar with the appearance of the parts involved, and has 
learned the chief facts concerning their structure. This acquaintance should be 
gained by careful study of their descriptive anatomy, and by frequent inspection 
and handling of well-dissected parts, prepared for this very purpose of pre- 
liminary drill. Without such equipment it is impossible to follow fully the 
admirable precept of Oliver Wendell Holmes—“ Let the eye go before the hand, 
and the mind before the eye.” 
Cooperation in Work.—The men who are dissecting on the same subject 
should work harmoniously. A spirit of accommodation is essential, for it is 
necessary that the attitude of a part and even of the whole cadaver should be 
changed at times, and occasionally this circumstance will oblige a student to alter 
his order of work temporarily, or even to suspend it altogether for a while. Those 
whose parts of the subject have a structural continuity or adjacency will sometimes 
work to best advantage at different hours. 
The Taking of Pains.—All work should be done with care and deliberation. 
Patience and intelligence are essential to good results. Hurry is not only waste- 
ful, but ineffective. The number of days which should be spent upon a stated 
part is not here prescribed, because competent men work with different degrees 
of speed. The task is soon enough done, when it is well enough done. 
Cleaning Organs.—“ The art of dissection consists in the complete removal of 
this [areolar] tissue from around the other structures, so as to expose the parts 
enwrapped therein” (Macalister). When the meshes of areolar tissue are occu- 
pied by cells of fat, dissection is much more difficult, and the result is less satis- 
factory. Consequently, when a choice is possible, a subject should be selected 
which is lean. 
Every part as it comes to view should be cleaned thoroughly—that is, freed 
from enveloping areolar tissue. 
In doing this, the cuts of the knife should be parallel with the fibres of the 
part, if it be muscle, nerve, or fascia; in the direction of its long axis, if it be a 
vessel. 
The vessels and nerves should be cleaned from large trunks to small. 
Finish the cleaning of one fasciculus or vessel before attempting another. 
In dissecting fine vessels and nerves, the point of the scalpel may be used to 
advantage; but in the dissection of muscles it is ordinarily advisable to employ 
the belly of the blade, making long, sweeping cuts. In this way greater smooth- 
ness of dissection is obtained. 
Whatever the part, it should be made tense before dissection. In the case of 
muscles the requisite tension may be gained by position; but in the case of a 
muscle whose fibres run in various directions, it is necessary to place the part in 
a different attitude for each of them. Blocks of wood, variously adjusted between 
883 884 
PRACTICAL ANATOMY. 
the thorax or abdomen and the table, assist greatly in this matter. Nerves may 
be made taut by the use of the hooks and chains. 
Further Directions.—The under surface of a muscle should always be examined 
carefully to observe the arteries, veins, nerves, and deep attachments. 
Every tendon should be followed to its attachment. 
In cutting through a muscle in order to remove or reflect it, care must be 
taken not to injure a subjacent part. 
If a muscle is to be reflected, it should, as a rule, be divided in the middle. 
When a group of muscles is to be reflected, each should be cut at a different 
level from the others, as replacement can thus be accomplished more readily and 
accurately. 
Handle parts delicately. Rough manipulation hurts them, especially the 
bellies of muscles. Forceps tear muscular fibres, and leave a ragged surface ; 
fingers injure them very little, and should always be used, when practicable. 
Do not finally remove any part until obliged to do so in order to reach under- 
lying structures. By keeping parts attached a long time, opportunity is afforded 
for many repeated examinations. , 
Prevention of Drying.—Fvery part should be kept a little moist (but not 
soaked) with some antiseptic liquid. One can learn something, perhaps a good 
deal, from a decaying organ; nothing from a part which has been allowed to dry. 
One of the best preparations for this purpose is composed as follows : Alcohol 
30 per cent., glycerine 10, carbolic acid 2, and water 58. 
Clearing up after Work.—After the day’s dissecting is done, the dissected 
organs should be slightly moistened with the above fluid, and adjusted as nearly 
as possible in their natural relations; the edges of the skin should be fastened 
with a continuous suture; and the whole wrapped in cotton cloth which has been 
wetted with the same solution. Finally, it is desirable that the entire subject 
should be covered with a sheet of rubber cloth. If care is taken along these 
lines, a dissection may be continued a number of weeks without discomfort or 
offence. 
The skin of a part should be saved until the dissection is completed, because 
it is the best covering. The original incisions should be so made as to leave 
large flaps of skin, as these are more easily managed. 
Disposal of Waste.—As regards the disposal of waste materials: all fluids 
from the subject should be turned into the waste-pipe connected with the sewer; 
small fragments should be deposited upon a piece of paper, and the collection 
from each day’s work placed in a box provided for the purpose, which should 
also receive the large masses, as they are removed; and the box should be 
buried at the close of the dissecting season, or as soon as it is filled, if that be 
earlier. 
Care of the Hands.—Chaps or abrasions on the hands of the dissector 
should be protected by small bits of court-plaster, over and around which a 
coating of flexible collodion is applied. When the hands are to be brought exten- 
sively in contact with the viscera, it is well to anoint them with vaseline or some 
other oil. 
Treatment of a Dissection Wound.—lf a wound is received from a dissecting 
instrument or a spicule of bone, it should be encouraged to bleed by holding it in 
the stream from the hot water faucet, and then sucking it vigorously, so that the 
poison may be removed before it has a chance to be absorbed. The danger of 
infection from the dissection material usually provided in our schools is very 
small, if reasonable precautions are observed. 
Cleanliness of Clothing.—ln preparation for dissection the student should 
either clothe himself in an old suit, which thereafter will be used for no other 
purpose, or else cover his ordinary raiment with a dissecting gown, which reaches 
nearly to his feet and is gathered in at the wrists. If consideration for his own 
cleanliness and comfort is not sufficient to suggest some such procedure, a decent 
regard for the rights of others will forbid his mingling with people of common PRACTICAL ANATOMY. 
885 
sensitiveness with a coat which is in any degree contaminated by contact with 
dissecting material, however well preserved the latter may be. 
Avoidance of Publicity.—The beginner in practical anatomy is usually so 
impressed with the novelty and interest of his work that he talks about it when 
among non-medical people, forgetting that to many of them the mention of such 
topics is offensive. In the interest of his own standing and of the repute of the 
profession he would far better maintain the strictest reticence in all such matters. 
Dissect Often !—Finally, in way of general advice, the student is counselled to 
lose no opportunity to dissect, bearing in mind that the most accomplished anato- 
mists never consider themselves so perfect in their knowledge that they cannot 
learn something by another dissection. 
Implements Needed.—The following instruments the student should provide 
himself with : a large scalpel, a small scalpel, both with the cutting edge markedly 
convex, a cartilage knife, a pair of scissors, best curved on the flat, a dissecting 
forceps, a tenaculum, a pair of hooks connected by a chain, a grooved director, a 
small blow-pipe, and a foot of rubber-tubing to fit onto the large end, and a large 
straight needle. The chisel, saw, and hammer, which he will need at times, are a 
part of the furnishings of the dissecting-room. Additionally he should procure 
some coarse thread for sewing the skin over the dissection at the close of the 
day; a pint of the preservative mentioned elsewhere in these directions; a piece 
of cotton cloth, large enough to enwrap his part of the subject; an ounce of 
vaseline for his hands ; and a good hone and strop for sharpening his knives— 
the strop never to be employed for other instruments after having been used for 
dissecting scalpels. He would do well to have his own cake of soap, nail-brush, 
and towels, for manifest reasons. 
The instruments, especially those for cutting, should be of excellent quality. 
There is no economy in buying inferior tools. 
After the day’s dissecting is done, every instrument which has been used 
should be scrupulously cleansed, dried, and made ready for the next session. The 
hands should be washed with hot water and soap, particular attention being 
bestowed upon the nails. 
DIVISION OF THE CADAVER. 
The number of parts into which the body is divided for dissection purposes 
varies greatly in different schools ; but the method of presentation here adopted 
will readily lend itself to any division which may be preferred. 
The organs in a given region arc mentioned in the order in which they are 
encountered in dissecting. The name of each is followed by a numeral which 
refers to the page of this book upon which it is described, with the exception 
that a few of the references direct attention to pictures, which are especially ser- 
viceable in dissecting, and from which the verbal descriptions can readily be 
turned to. 
Many parts are entered more than once in the enumerations, because they 
occur in two or more regions. 
The small branches of arteries are not generally given, as they will naturally 
attract attention in connection with the trunks from which they spring. The same 
omission is commonly made in the case of veins which are companion to arteries 
of the same name. Reference to a viscus is intended to include its parts, as 
ducts, vessels, etc. 
It is assumed that the dissection is done under the personal supervision of a 
competent demonstrator, who will prescribe the order in which parts are to be 
taken, and will give all necessary instructions as to the best method of making 
primary incisions, reflecting and removing parts, and displaying whatever requires 
demonstration—points upon which equally competent teachers differ—and, there- 
fore, specific directions on such matters are not here given. 886 
PRACTICAL ANATOMY. 
THE THORAX AND UPPER LIMB. 
Platysma, 337. 
Cutaneous nerves, 605, 619, 621. 
Mammary gland, 843. 
Cephalic vein, 470. 
Acromiothoracic artery, 415. 
Deep fascia, 353, 354. 
Pectoralis major, 260. 
Axillary space, 415. 
Lymph-nodes, 492. 
Axillary vein, 470. 
Axillary artery, 412, 
Brachial plexus, 606. 
Pectoralis minor, 256. 
Costocoracoid membrane, 354. 
Subclavius, 257. 
Serratus magnus, 256. 
Posterior thoracic nerve, 607. 
Intercosto-humeral nerve, 620. 
Intercostales extend, 336. 
Intercostales intend, 336. 
Intercostal nerves, 619. 
Intercostal arteries, 425. 
Internal mammary artery, 409. 
Superior epigastric artery, 410. 
Musculophrenic artery, 409. 
Sternal lymph-nodes, 495. 
Triangularis sterni, 336. 
Superior mediastinal lymph-nodes, 495. 
Gangliated cord of the sympathetic, 642. 
Azygos veins, 471. 
Posterior mediastinal lymph-nodes, 495. 
Diaphragma, 334. 
Costo-vertebral articulations, 211. 
Front of the Arm. 
Cutaneous nerves, 617. 
Superficial veins in arm and at bend of 
elbow, 468. 
Epicondylar lymph-node, 493. 
Deep fascia, 355. 
External and internal intermuscular 
septa, 355. 
Brachial artery, 415. 
Venae comites of brachial artery, 470. 
Internal cutaneous nerves, 612. 
Median nerve, 608. 
Ulnar nerve, 612. 
Musculo-cutaneous nerve, 608. 
Biceps, 263. 
Coracobrachialis, 260. 
Brachialis, 264. 
Front of the Forearm. 
Thoracic Cavity. 
Superficial veins, 469. 
Cutaneous nerves, 617, 618. 
Deep fascia, 355. 
Intermuscular septa, 356. 
Pronator teres, 267. 
Flexor carpi radialis, 269. 
Palmaris longus, 269. 
Flexor carpi ulnaris, 269. 
Radial artery, 421. 
Flexor sublimis digitorum, 273. 
Radial and posterior interosseous nerves, 
616. 
Pleurse, 765. 
Anterior mediastinal lymph-nodes, 495. 
Lungs, 762. 
Roots of lungs, 763. 
Phrenic nerve, 605. 
Pericardium, 373. 
Thymus, 797. 
Brachio-cephalic veins, 457. 
Superior vena cava, 456. 
Inferior vena cava, 474. 
Heart, 365. 
Coronary arteries, 386, 
Cardiac veins, 455. 
Cardiac nerves, 595, 643, 644. 
Ulnar artery, 417, 
Interosseous arteries, 418. 
Median nerve, 608. 
Flexor profundus digitorum, 274. 
Flexor longus pollicis, 282. 
Pronator quadratus, 267. 
Pulmonary artery, 379. 
Aorta, 383. 
Brachio-cephalic artery, 386. 
Left common carotid artery, 389, 
Left subclavian artery, 404. 
Trachea, 757. 
The Palm. 
Palmaris brevis, 285. 
Cutaneous nerves, 617, 618. 
Anterior annular ligament, 356. 
Palmar fascia, 356. 
Synovial sheaths of tendons, 357. 
Superficial palmar arch, 420. 
Ulnar nerve, 612. 
Bronchi, 758. 
Pneumogastric nerves, 592. 
Recurrent laryngeal nerves, 594. 
Gullet, 712, 
Branches of descending aorta, 425. 
Thoracic duct, 487. PEA OTIC A L A JVA TO MY. 
887 
Median nerve, 608. 
Abductor pollicis, 284. 
Flexor ossis metacarpi pollicis, 281. 
Flexor brevis pollicis, 282. 
Adductor pollicis, 284. 
Abductor minimi digiti, 279. 
Flexor brevis minimi digiti, 275. 
Flexor ossis metacarpi minimi digiti, 
275. 
Musculospinal nerve, Gl4. 
Superior profunda artery, 416. 
Ulnar nerve, 612. 
Anastomotica niagna and anastomoses 
around elbow, 416. 
Back of the Forearm. 
Cutaneous nerves, 617, 618. 
Deep fascia, 355. 
Anconeus, 266. 
Brachioradialis, 265. 
Extensor carpi radialis longns, 269. 
Extensor carpi radialis brevis, 270. 
Extensor communis digitorum, 277. 
Extensor minimi digiti, 278. 
Extensor carpi nlnaris, 270. 
Extensor ossis metacarpi pollicis, 282. 
Extensor brevis pollicis, 282. 
Extensor longns pollicis, 282. 
Extensor indicis, 278, 
Posterior interosseous artery, 418. 
Posterior interosseous nerve, 616. 
Supinator, 268. 
Lumbricales, 276. 
Deep palmar arch, 422. 
Interossei palmares, 280 
Back of Thorax and Upper Limb 
Deep fascia, 354. 
Trapezius, 253. 
Latissiraus, 261. 
Omohyoidens, 337. 
Phomboideus minor, 255. 
Phomboideus major, 255. 
Deltoideus, 258. 
Circumflex arteries, 415. 
Circumflex nerve, 613. 
Teres major, 261. 
Supraspinatus, 260. 
Infraspinatus, 261. 
Teres minor, 261. 
Subscapularis, 263. 
Suprascapular artery, 410. 
Suprascapular nerve, 607. 
Dorsalis scapulae artery, 415. 
Back of the Hand. 
Radial artery, 422. 
Posterior annular ligament, 356. 
Digital extensors, tendons, 276. 
Posterior interosseous nerve, 616. 
Interossei dorsales, 278, 
The articulations of the upper limb : 
Sterno-clavicular joint, 216. 
Scapulo-clavicular joint, 217. 
Shoulder joint, 218. 
Elbow joint, 221. 
Wrist joint, 224. 
Joints in the hand, 225-227. 
Deep fascia, 355. 
Cutaneous nerves, 617, 618. 
Triceps, 265. 
Back of the Arm. 
THE ABDOMEN AND LOWER LIMB. 
Superficial fascia—two layers, 349. 
Lymph-nodes in groin, 493. 
Cutaneous nerves : 
The Abdomen. 
Obliquus interims, 332. 
Cremaster, 333. 
Nerves in abdominal wall 
Anterior cutaneous, 621. 
Lateral cutaneous, 621. 
Ilio-hypogastric, 623. 
Ilio-inguinal, 624. 
Last thoracic, 621. 
Superficial pudic arteries, 443. 
Superficial epigastric artery, 443. 
Superficial circumflex iliac artery, 443 
Obliquus externus, 332. 
Linea alba, 331. 
External abdominal ring, 332. 
Inguinal ligament, 332. 
Gimbernat’s ligament, 332. 
Intercostals—lower six, 619. 
Last thoracic, 621. 
Ilio-hypogastric, 623. 
Ilio-inguinal, 624. 
Transversalis, 333, 
Pectus abdominis, 331. 
Pyramidalis, 332. 
Linea alba, 331. 
Lumbar fascia, 358. 
Transversalis fascia, 359. 
Internal abdominal ring, 360. 
Objects in anterior abdominal wall 
below umbilicus, 752. 
Deep epigastric artery, 438. 888 
PRACTICAL ANATOMY. 
Deep circumflex iliac artery, 439. 
Superior epigastric artery, 410. 
Musculo-phrenic artery, 409. 
Scrotum, 809. 
Spermatic cord, 812. 
Testicles, 801. 
Penis, 812. 
The Pelvic Cavity of the Male, 
Hypogastric plexus, 647. 
Pelvic fascia, 360. 
Bladder, 785. 
Ureters, 784. 
Prostate, 818. 
Rectum, 732. 
Seminal vesicles, 808. 
Vasa deferentia, 807. 
Internal iliac artery, 433. 
Obturator artery, 434. 
Internal pudic artery, 435. 
Sciatic artery, 436. 
Ilio-lumbar artery, 437. 
Gluteal artery, 437. 
Lateral sacral artery, 437. / 
Internal iliac lymph-nodes, 497. 
Superior hemorrhoidal artery, 431. 
Middle sacral artery, 432. 
Sacral plexus, 628. 
Sacral lymph-nodes, 497. 
Gangliated cord of sympathetic, 648. 
Coccygeal gland, 800. 
Obturator interims, 299. 
Pyriforrais, 298. 
Deep inguinal lymph-nodes, 494. 
Articulations of pelvis, 227. 
Abdominal Cavity. 
Abdomen Proper. 
Liver, 738. 
Spleen, 793. 
Stomach, 715. 
Gullet, 712. 
Jejuno-ileum, 723. 
Ctecum, 727. 
Colon, 728. 
Peritoneum, 748. 
Foramen of Winslow, 751. 
Mesentery proper, 749. f 
Lymph-nodes of mesentery, 497. 
Superior mesenteric artery, 429. 
Inferior mesenteric artery, 430. 
Aortic plexus of nerves, 647. 
Branches of abdominal aorta, 427. 
Portal vein, 477. 
Duodenum, 721. 
The Pelvic Cavity of the Female, 
Pancreas, 736. 
Pneumogastric nerves, 592. 
Solar plexus, 649. 
Lumbar lymph-nodes, 497. 
Kidney, 777. 
Suprarenal capsules, 798. 
Ureters, 784. 
Diaphragraa, 334. 
Abdominal aorta, 426. 
Receptaculum chyli, 487. 
Inferior vena cava, 474. 
Ganglia of sympathetic, 646. 
Common iliac vessels, 432, 476. 
External iliac vessels, 438, 477. 
External iliac lymph-nodes, 497. 
Iliac fascia, 360, 
Psoas magnus, 290. 
Iliacus, 291. 
Quadratus lumborum, 334. 
Psoas parvus, 323. 
Lumbar plexus, 622, 
Last thoracic nerve, 621. 
Ilio-hypogastric nerve, 623. 
Ilio-inguinal nerve, 624. 
Genito-crural nerve, 624. 
External cutaneous nerve, 624. 
Anterior crural nerve, 624. 
(Organs not in mule pelvis.) 
Uterus, 829. 
Broad ligaments, 832. 
Ovaries, 822. 
Parovaria, 835. 
Fallopian tubes, 827. 
Round ligaments, 832. 
Urethra, 788, 
Uterine artery, 434. 
Vaginal artery, 434. 
Ovarian artery, 431. 
The Male Perineum. 
Superficial fascia, 361. 
Sphincter ani externus, 821. 
Superficial perineal artery, 436. 
Transverse perineal artery, 436. 
Superficial perineal nerves, 631. 
Inferior pudendal nerve, 630. 
Ischio-rectal fossa, 361. 
Transversus perinei, 821. 
Central point of perineum, 820. 
Bulbo-cavernosus, 821, 
Ischio-cavernosus, 821. 
Bulb of corpus spongiosum, 814. 
Crura penis, 813. PR A CTICA L ANA TOMY. 
889 
Internal pudic artery, 435. 
Pudic nerve, 631. 
Vastus interims, 307. 
Vastus intermedins, 307. 
Inferior hemorrhoidal artery, 436. 
Inferior hemorrhoidal nerve, 631. 
Triangular ligament, 361. 
Musculus articularis genu, 308. 
Ligamentum patellae, 303. 
Prepatellar bursa, 155. 
Membranous urethra, 789. 
Constrictor urethrae, 822. 
Bui bo-urethral glands, 820. 
Levator ani, 821. 
Inner Side of the Thigh. 
Adductor longus, 294. 
Profunda femoris artery, 443. 
Perforating arteries, 443. 
Pectineus, 297. 
Internal circumflex artery, 443. 
Adductor brevis, 297. 
Gracilis, 297. 
Adductor magnus, 294. 
Obturator externus, 298. 
Obturator nerve, 626. 
Obturator artery, 434. 
Psoas magnus, 290, 
Iliacus, 291. 
Coccygeus, 821. 
Anal canal, 734. 
Seminal vesicles, 808. 
Prostate gland, 818. 
The Female Perineum. 
Vulva, 837. 
Vagina, 835. 
Cervix uteri, 830, 
Bulbs of vestibule, 841. 
Vulvo-vaginal glands, 841. 
Front of the Leg and Dorsum of the 
Foot. 
Superficial epigastric artery, 443. 
Superficial external pudic artery, 443. 
Superficial circumflex iliac artery, 443. 
Lymph-nodes, 493. 
Internal saphenous vein, 481. 
Cutaneous nerves : 
Front of the Thigh. 
Superficial veins, 481. 
Cutaneous nerves: 
External popliteal, 636. 
External saphenous, 633. 
Internal saphenous, 625. 
Musculo-cutaneous, 637. 
Anterior tibial, 637. 
1110-inguinal, 624. 
Genito-crural, 624. 
Long saphenous, 625. 
External cutaneous, 624. 
Middle cutaneous, 624. 
Internal cutaneous, 625. 
Fascia lata, 362. 
Deep fascia, 362. 
Anterior annular ligament, 363. 
Internal annular ligament, 363. 
Intermuscular septa, 363. 
Tibialis anterior, 308. 
Extensor longus digitorum, 319. 
Extensor proprius hallucis, 319, 
Peroneus tertius, 308. 
Anterior tibial artery, 450. 
Malleolar arteries, 452. 
Dorsalis pedis artery, 452. 
Tarsal arteries, 452, 
Metatarsal arteries, 453. 
Interossei dorsales, 322. 
Peroneal artery, 447. 
Extensor brevis digitorum, 319. 
Anterior tibial nerve, 637. 
Ilio-tibial band, 362. 
Intermuscular septa, 362. 
Saphenous opening, 362. 
Inguinal ligament, 332. 
Gimbemat’s ligament, 332. 
Femoral canal, 362. 
Femoral sheath, 359. 
Scarpa’s triangle, 440, 
Femoral artery, 439. 
Profunda artery, 443. 
Deep external pudic artery, 443. 
Sartorius, 301. 
Adductor (Hunter’s) canal, 440. 
Anastomotica magna artery, 443. 
Femoral vein, 482. 
Outer Side of the Leg. 
External annular ligament, 363. 
Peroneus longus, 316. 
Peroneus brevis, 316. 
Peroneal artery, 447. 
External popliteal nerve, 636. 
Musculo-cutaneous nerve, 637. 
Anterior crural nerve, 624. 
External circumflex artery, 443. 
Tensor vaginae femoris, 292. 
Rectus femoris, 304. 
Vastus externus, 307. 890 
PRACTICAL ANATOMY. 
Back of the Hip. 
Intermuscular septa, 363. 
External annular ligament, 363. 
Internal annular ligament, 363. 
Gastrocnemius, 309. 
Plantaris, 314. 
Soleus, 313. 
Tendo-calcaneus, 314. 
Popliteal artery, 443. 
Posterior tibial artery, 446. 
External popliteal nerve, 636. 
Posterior tibial nerve, 633. 
Deep transverse fascia, 363, 
Popliteus, 302. 
Flexor longus hallucis, 316. 
Flexor longus cligitorum, 317. 
Tibialis posterior, 308. 
Peroneal artery, 447, 
Cutaneous nerves: 
Sacral, 628. 
Lumbar, 622. 
Ilio-hypogastric, 623. 
Last thoracic, 621. 
External cutaneous of thigh, 624. 
Small sciatic, 629. 
Fascia lata, 362. 
Gluteus maximus, 291. 
Small sciatic nerve, 629. 
Great sciatic nerve, 631. 
Internal pudic artery, 435. 
Internal pudic nerve, 631. 
Pyriformis, 298. 
Sciatic artery, 436. 
Obturator internus and gemelli, 298- 
301. 
Quadratus femoris, 298. 
Obturator externus, 298. 
Internal circumflex artery, 443. 
Gluteus medius, 292. 
Gluteal artery, 437. 
Superior gluteal nerve, 629. 
Gluteus minimus, 292, 
The Sole. 
Internal calcaneal nerve, 634. 
Plantar fascia, 364. 
Abductor hallucis, 321. 
Flexor brevis digitorum, 317. 
Abductor minimi digiti, 321. 
Internal plantar nerve, 634. 
Internal plantar artery, 449. 
External plantar artery, 449. 
External plantar nerve, 635. 
Flexor tendons, 318. 
Accessorius, 317. 
Lumbricales, 318. 
Flexor brevis hallucis, 317. 
Adductor obliquus hallucis, 322. 
Adductor transversus hallucis, 322. 
Flexor brevis minimi digiti, 317. 
Plantar arch, 449. 
Dorsalis pedis,plan tar digital branch,4s3. 
Interossei plantares, 323. 
Peroneus longus tendon, 318. 
Articulations of lower limb : 
Cutaneous nerves, 640. 
Deep fascia, 362. 
Biceps flexor cruris, 301. 
Semitendinosus, 301. 
Semimembranosus, 301. 
Great sciatic nerve, 631. 
Perforating arteries, 443. 
External saphenous vein, 481. 
Small sciatic nerve, 629. 
Popliteal space, 444. 
Internal popliteal nerve, 632. 
External popliteal nerve, 636. 
Popliteal artery, 443. 
Popliteal vein, 482. 
Popliteal lymph-nodes, 494. 
Back of the Thigh. 
Hip joint, 230. 
Knee joint, 233. 
Ankle joint, 239. 
Tarsal joints, 240. 
Tarso-metatarsal joints, 243. 
Metatarso-phalangeal joints, 244. 
Phalangeal joints, 244. 
Back of the Leg. 
Superficial veins, 481. 
Cutaneous nerves, 640. 
Deep fascia, 363. 
Cranial Region. 
THE 
HEAD AND NECK. 
In the superficial fascia : 
Attollens aurem, 678. 
Attrahens aurem, 679. 
Ketrahens aurem, 679. 
Supratrochlear nerve, 576. 
Supraorbital nerve, 576. 
Facial nerve, temporal branches, 588 
Orbital nerve, 578. 
Anricnlo-temporal nerve, 582. 
Posterior auricular nerve, 587. 
Great auricular nerve, mastoid branch 
604. 
Small occipital, 604. PRACTICAL ANATOMY. 
891 
Great occipital nerve, 602. 
Epicranial aponeurosis, 348. 
Occipitalis, 348. 
Frontalis, 348. 
Temporal fascia, 350. 
Side of the Neck. 
Platysma, 337. 
External jugular vein, 460. 
Superficial cervical lymph-nodes, 490. 
Anterior jugular vein, 460. 
Cervical plexus, superficial branches, 
604, 605. 
Facial nerve, inframandibular branch, 
588. 
Inside of the Cranium. 
Encephalon (to be hardened for subse- 
quent study), 509. 
Dura, 558. 
Venous sinuses of dura, 463. 
Cranial nerves at foramina of exit, 
565. 
Deep fascia, 351. 
Sternocleidomastoideus, 337. 
Triangles of the neck, 411. 
Subclavian artery, 404. 
Suprascapular artery, 410. 
Transversalis colli artery, 411. 
Brachial plexus, 606. 
Supraclavicular branches : 
to rhomboids, 606. 
to subclavius, 607. 
suprascapular, 607. 
posterior thoracic, 607. 
Sternohyoideus, 337. 
Omohyoideus, 337. 
Sternothyroideus, 337. 
Thyrohyoideus, 338. 
Stylomandibular ligament, 350, 352. 
Digastricus, 338. 
Stylohyoideus, 338. 
Hypoglossal nerve, 596. 
Scalenus anterior, 339. 
Scalenus medius, 339. 
Internal carotid artery, 401. 
Meningeal arteries, middle and small, 
400. 
Vertebral arteries, 406 
Hypophysis, 534. 
Back of the Neck 
Superficial nerves : 
Great occipital, 602. 
Branches of third, fourth, and fifth 
cervical, 603-606. 
Small occipital, 604. 
Great auricular, 604. 
Trapezius, 253. 
Spinal accessory nerve, 596. 
Levator scapulae, 254. 
Transversalis colli artery, 411. 
Omohyoideus, posterior belly, 337. 
Posterior scapular artery; 411. 
Suprascapular artery, 410. 
Suprascapular nerve, 607. 
Vertebral fascia, 358. 
Scalenus posterior, 340. 
Subclavian artery, 404. 
Vertebral artery, 406. 
Thyroid axis, 410. 
Inferior thyroid artery, 410. 
Internal mammary artery, 409. 
Superior intercostal artery, 411. 
Subclavian vein, 470. 
Thoracic, or right lymphatic, duct, 487. 
Cervical pleura, 765. 
Cervical plexus, muscular branches of, 
605. 
Splenius cervicis, 327. 
Splenius capitis, 326. 
Cervicalis ascendens, 329. 
Transversalis cervicis, 329. 
Trachelomastoideus, 329. 
Occipital artery, 397. 
Complexus, 329. 
Ligamentum nuchse, 207. 
Arteria princeps cervicis, 398. 
Cervical spinal nerves, dorsal primary 
divisions, 602. 
Semispinalis cervicis, 330, 
Multifidus, 330. 
Rectus capitis posterior major, 330. 
Rectus capitis posterior minor, 331. 
Obliquus capitis inferior, 331. 
Obliquus capitis superior, 331. 
Suboccipital nerve, dorsal primary di- 
vision, 602. 
Ramus cervicalis descendens, 605, 
Phrenic nerve, 605. 
Communicating branches, 605. 
Carotid artery (common and internal), 
389, 401. 
Internal jugular vein, 461. 
Pneumogastric nerve, 592. 
Deep cervical lymph-nodes, 489. 
Carotid gland, 800. 
External carotid artery, 392. 
Superior thyroid artery, 393. 
Lingual artery, 395. 
Facial artery, 396. 
Occipital artery, 397. 
Vertebral artery, 406. 892 
PBA CTICAL ANA TOMY 
Posterior auricular artery, 398. 
Ascending pharyngeal artery, 398. 
Thyroid body, 796. 
Trachea, 757. 
Gullet, 712. 
Chorda tympani, 587. 
Otic ganglion, 584. 
Mandibular Region. 
Mylohyoideus, 338. 
Hyoglossus, 709.. 
Styloglossus, 709. 
Geniohyoideus, 339. 
Submaxillary gland, 735. 
Sublingual gland, 736. 
Lingual nerve, 583. 
Submandibular ganglion, 583. 
Hypoglossal nerve, 596. 
Genioglossus, 709. 
Lingual artery, 395. 
The Face. 
Platysma, 337. 
Great auricular nerve, facial branch, 605. 
Parotid gland, 735. 
(In the parotid: external carotid, 
temporal, and internal maxil- 
lary arteries, temporomaxillary 
vein, facial, great auricular, and 
auriculotemporal nerves.) 
Temporal artery, 398. 
Orbicularis palpebrarum. 
Corrugator supercilii, 347. 
Eyelids, 691. 
Pi so ri us, 346. 
Levator labii superioris alseque nasi, 346. 
Levator labii superioris proprius, 346. 
Zygomaticus minor, 346. 
Zygomaticus major, 346. 
Levator anguli oris, 346. 
Depressor labii inferioris, 346. 
Depressor anguli oris, 346. 
Buccinator, 346. 
Orbicularis oris, 345. 
Deep Parts of the Neck. 
Stylopharyngeus, 711. 
Internal carotid artery, 401. 
Ascending pharyngeal artery, 398. 
Internal jugular vein, 461. 
Glossopharyngeal nerve, 591. 
Pneumogastric nerve, 592. 
Pharyngeal nerve, 594. 
Superior laryngeal nerve, 594. 
Inferior laryngeal nerve, 594. 
Cardiac nerves, 595. 
Spinal accessory nerve, 596. 
Pharyngeal plexus, 596. 
Hypoglossal nerve, 596. 
Sympathetic ganglia of neck, 642. 
Rectus capitis lateralis, 340. 
Levator meuti, 346. 
Nasal muscles, 347. 
Facial nerve and branches, 585. 
Trifacial nerve and branches, 574. 
Facial artery and branches, 396. 
Facial vein, 457. 
Pinna, 678. 
Eyelids, 691. 
Levator palpebrse, 691. 
Lachrymal gland, 694. 
Lachrymal canals, 694. 
Nasal duct, 666. 
Nasal cartilages, 664. 
Prevertebral Region. 
Longus colli, 341, 
Rectus capitis anterior major, 340 
Rectus capitis anterior minor, 340 
Cervical nerves, 605. 
Vertebral artery, 406. 
The Orbit. 
Temporal and Zygomatic Fossae. 
Eyeball, 381. 
Capsule of Tenon, 381. 
Frontal nerve, 576. 
Supraorbital artery, 402. 
Lachrymal nerve, 576. 
Nasal nerve, 576. 
Lachrymal gland, 694. 
Levator palpebrse superioris, 691. 
Rectus superior, 690. 
Obliquus superior, 690. 
Optic nerve, 568. 
Ophthalmic ganglion, 577. 
Ophthalmic artery, 402. 
Temporal fascia, 350. 
Masseter, 342. 
Temporalis, 342. 
Pterygoideus extern us, 342. 
Pterygoideus interims, 342. 
Internal maxillary artery, 399. 
Internal maxillary vein, 460. 
Trifacial nerve, mandibular division,sBo. 
Long buccal nerve, 582. 
Auriculotemporal nerve, 582. 
Inferior dental nerve, 582. 
Lingual nerve, 583. 
o y PRACTICAL ANATOMY. 
893 
Rectus externus, 690. Eustachian tube, 676. 
Rectus interims, 690. The larynx, 767. 
Ligament of Zinn, 690. The nasal fossae, 664. 
Oculomotor nerve, 571. 
AMucent nerve 585 The Back 
Ciliary nerves, 5/6, on. 
Obliquus inferior, 691. Deep fasciae, 358. 
Rectus inferior, 690. Muscles in third layer, 325. 
Orbital nerve, 578. Muscles in fourth layer, 327. 
The ear, 668. Muscles in fifth group, 329. 
The mouth, 698. Branches of lower thoracic and upper 
Tongue, 707. lumbar nerves, 619. 
The pharynx, 710. Intercostal nerves, 619. 
Soft palate, 700. The spinal cord, 552. 
Tonsils, 711. Membranes of cord, 561. INDEX 
Anatomy, clinical, 20 
comparative, 18 
definition of, 17 
A. 
Aponeurosis, 348 
Apophysis, 115 
Appendages of the eye, 691 
Appendices epiploicse, 729 
Appendix vermiformis, 728 
Applied anatomy, 20 
Aqueduct of Fallopius, 174 
of mesencephalon, 539 
region of, 538 
Aqueductus cochleae, 674 
vestibuli, 673 
Aqueous humor, 689 
Arachnoid of brain, 560 
of spinal cord, 562 
Arantius, body of, 368 
Arbor vitae, cerebellar, 542 
uterina, 830 
Arch, deep crural, 360 
palmar, 422 
neural, 115 
posterior carpal, 420 
superficial palmar, 420 
Arciform nuclei, 547 
Area, auditory, 551 
embryonic, 82 
hypoglossal, 551 
opaca, 82 
pellucida, 82 
vagus, 551 
vasculosa, 83 
Areola of breast, 843, 844 
secondary, 845 
Areolar tissue, 47 
Arm, back of, dissection of, 887 
fascia of, 355 
front of, dissection of, 886 
muscles moving, 258 
Arnold’s nerve, 594 
Abdomen, lymph-nodes of, 497 
muscles of, 331 
regions of, 714 
Abdominal aorta, 426 
branches of tenth, 596 
cavity, 713 
dissection of, 888 
fascia of, 359 
ring, external, 332 
internal, 360 
walls, dissection of, 887 
Abducent nerve, 585 
Abductor hallucis, 321 
longus pollicis, 282 
minimi digiti, 279 
pedis, 321 
pollicis muscle, 284 
Accessorius ad ilio-costalem, 329 
Accessory obturator nerve, 626 
olivary nuclei, 547 
spleens, 795 
thyroid glands, 797 
Acetabulum, 149 
Acoustic tubercle, 551 
Acromio-thoracic artery, 414 
Adductor brevis muscle, 297 
gracilis muscle, 297 
longus muscle, 294 
magnus muscle, 294 
obliquus hallucis, 322 
pollicis muscle, 284 
transversus hallucis, 322 
Adenoid reticular tissue, 50 
Adipose tissue, 49 
Adrenals, 798 
After-birth, 85 
Aggregated lymph-nodules, 724 
Agminated glands, 724 
Ala, cerebellar, 543 
Albicantia, corpora, 522, 534 
Alimentary canal, tunics of, 697 
Allantois, 83 
Alveolar artery, 401 
Amniotic cavity, 84 
fold, 83 
Amoeba, 695 
Amoeboid movements, 38 
Amphiarthrosis, 204 
Ampulla of Henle, 808 
rectal, 733 
of semicircular canal, 669 
Amygdala, 526, 711 
cerebellar, 544 
Amygdaloid nucleus, 526 
Anal canal, 734 
columns, 734 
Anastomotica magnaof brachial, 
416 
descriptive, 18 
general, 19 
gross, 18 
macroscopic, 18 
medical, 18 
microscopic, 18 
minute, 18 
morphological, 20 
normal, 20 
pathological, 20 
philosophic, 20 
physiological, 20 
practical, 20, 883 
regional, |8 
relational! 18,4Wf 
surface, 857 
surgical, 18 
systematic, 18 
topographical, 18 
transcendental, 20 
Anconeus muscle, 266 
Angular artery, 397 
gyrus, 516 
veins, 458 
Ankle-joint, 239 
Annular ligament of ankle, an 
terior, 363 
external, 363 
internal, 363 
of carpus, anterior, 356 
of forearni, posterior, 356 
Annulus ovalis, 367 
Ansa hypoglossi, 597 
Anterior brachium, 533 
commissure, 522 
crural nerve, 624 
forceps, 519 
interosseus nerve, 610 
ligament of uterus, 832 
nares, 663 
palatine nerve, 580 
perforated space, 525 
superior dental nerves, 578 
tibial nerve, 637 
Arrectores pilorum, 658 
Arteria centralis retinae, 687 
Arterial circle of Huguier, 834 
system, pulmonary, 379 
Arteries, helicine, 817 
Artery or arteries, 379 
acromio-thoracic, 414 
alar thoracic, 415 
alveolar, 401 
anastomotica magna of brach 
ial, 416 
of femoral, 443 
angular, 397 
anterior auricular, 399 
carpal of radial, 422 
of ulnar, 420 
cerebral, 403 
choroid, 403 
ciliary, 402 
circumflex, 415 
communicating, 403 
ethmoidal, 402 
Antihelix, 678 
fossa of, 678 
Anti tragus, 678 
Antrum of Highmore, 183 
mastoid, 675 
maxillary, 666 
pyloricum, 716 
sphenoidal, 666 
Anus, 734 
Aorta, 383 
abdominal, 426 
arch of, 383 
descending, 423 
thoracic, 423 
Aortic plexus, 647 
funicular, 834 
intercostal, 409 
of femoral, 443 
Anatomy, applied, 20 
artistic, 20 
valve, 369 
interosseous, 418 
895 896 
INDEX. 
Artery or arteries, anterior men 
ingeal, 402 
spinal, 407 
temporal, 399 
tibial, 450 
recurrent, 451 
articular, of popliteal, 145 
of sciatic, 437 
Artery or arteries, deep external 
pudic, 443 
palmar, of ulnar, 420 
dental, inferior, 400 
descending palatine, 401 
development of, 95 
digital, of external plantar, 449 
of ulnar, 420 
Artery or arteries, interosseous, 
of ulnar, 418 
intestinal, 430 
labial, inferior, 397 
lachrymal, 402 
laryngeal, inferior, 410 
superior, 395 
lateral nasal, 397 
sacral, 437 
azygos, 446 
ascending cervical, 410 
palatine, 397 
pharyngeal, 398 
auricular, 397 
anterior, 399 
posterior, 398 
axillary, 412 
azygos articular, 446 
basilar, 408 
brachial, 415 
brachio-cephalic, 386 
bronchial, 425 
dorsal interosseous, 422 
lingual, 396 
of penis, 436 
dorsalis hallucis, 453 
indicis, 422 
spinal, 407 
left carotid, in the thorax, 389 
colic, 431 
lenticnlo-striate, 404 
lingual, 395 
dorsal, 396 
long ciliary, 402 
thoracic, 415 
pedis, 452 
pollicis, 422 
scapulae, 415 
epigastric, deep, 438 
superior, 410 
ethmoidal, 402 
anterior, 402 
external carotid, 392 
lumbar, 431 
malleolar, 452 
mammary, internal, 409 
masseteric, 401 
maxillary, internal, 399 
mediastinal, 409 
posterior, 425 
meningeal, 398 
anterior, 402 
buccal, 401 
calcanean, internal, 449 
carotid, common, in neck, 389 
external, 392 
internal, 401 
left, in thorax, 389 
carpal, anterior, of radial, 422 
of ulnar, 420 
posterior, of radial, 422 
of ulnar, 420 
recurrent, 423 
central of retina, 402 
cerebellar, posterior inferior, 
408 
circumflex, 443 
iliac, 438 
obturator, 434 
plantar, 449 
pudic, deep, 443 
superficial, 443 
facial, 396 
transverse, 398 
femoral, 439 
frontal, 403 
gastric, 427 
gastro duodenalis, 428 
-epiploica dextra, 428 
sinistra, 429 
glandular, 397 
gluteal, 437 
hemorrhoidal, inferior, 436 
middle, 434 
superior, 431 
hepatic, 427, 739 
hyoid, 395, 396 
ileo-colic, 430 
iliac, common, 432 
deep circumflex, 439 
external, 438 
internal, 433 
superficial circumflex, 443 
ilio-lumbar, 437 
inferior dental, 400 
hemorrhoidal, 436 
labial, 397 
laryngeal, 410 
mesenteric, 430 
pancreatico duodenalis, 430 
profunda, 416 
thyroid, 410 
infraorbital, 401 
intercostal, 425 
anterior, 409 
collateral, 425 
superior, 411 
internal calcanean, 449 
carotid, 401 
circumflex, 443 
iliac, 433 
middle, 400 
posterior, 407 
small, 400 
mesenteric, inferior, 430 
superior, 429 
metatarsal, 453 
middle cerebral, 403 
colic, 430 
hemorrhoidal, 434 
meningeal, 400 
temporal, 399 
musculo-phrenic, 409 
nasal, 402 
lateral, 397 
nutrient of brachial, 416 
cerebral, anterior, 403 
hemisphere, 530 
middle, 403 
cervical, ascending, 410 
deep, 411 
superficial, 411 
choroid, anterior, 403 
ciliary, 686 
anterior, 402 
to clavicle, 411 
to fibula, 448 
to tibia, 449 
obturator, 434 
external, 434 
internal, 434 
occipital, 397 
oesophageal, 410, 425 
of bulb, 436 
of upper limb, 404 
ophthalmic, 402 
ovarian, 431 
palatine, ascending, 397 
descending, 401 
palmar, deep, of ulnar, 420 
palpebral, 402 
pancreatic, 429 
pancreatico-duodenalis, supe 
rior, 428 
inferior, 430 
perforating, 409 
of profunda, 443 
of radial, 423 
posterior, 449 
pericardial, 425 
perineal, superficial, 436 
transverse, 436 
long, 402 
short, 402 
circumflex, anterior, 415 
external, 443 
iliac, deep, 439 
superficial, 443 
internal, 443 
posterior, 415 
coccygeal, 437 
colic, 430 
left, 431 
middle, 430 
right, 430 
collateral intercostal, 425 
comes nervi ischiadic!, 437 
common carotid, in the neck, 
389 
iliac, 432 
communicating, anterior, 403 
dorsalis pedis, 453 
peroneal, 448 
posterior, 403 
of posterior tibial, 449 
coronary, of the face, 397 
corpus cavernosum, 436 
cremasteric, 438 
crico-thyroid, 395 
cystic, of hepatic, 428 
deep cervical, 411 
circumflex iliac, 439 
mammary, 409 
maxillary, 399 
obturator, 434 
plantar, 449 
pudic, 435 
interosseous, anterior, 418 
dorsal, 422 
peroneal, 447 
pharyngeal, 398 
ascending, 398 
phrenic, 431 
superior, 409 
plantar, external, 449 
posterior, 418 
epigastric, 438 
of radial, 422 
internal, 449 INDEX. 
897 
Artery or arteries, popliteal, 443 
posterior auricular, 398 
carpal, of radial, 422 
of ulnar, 420 
circumflex, 415 
communicating, 403 
inferior cerebellar, 408 
Artery or arteries, superior 
phrenic, 409 
profunda, 416 
thoracic, 414 
thyroid, 393 
supra-acromial, 411 
supraorbital, 402 
suprarenal, 431 
suprascapular, 410 
suprasternal, 410 
tarsal, 452 
temporal, 398, 401 
anterior, 399 
middle, 399 
posterior, 399 
thoracic, alar, 415 
long, 415 
superior, 414 
thyroid, inferior, 410 
superior, 393 
thyroidea ima, 389 
tibial, anterior, 450 
posterior, 446 
recurrent, anterior, 451 
posterior, 451 
tonsillar, 397 
Articulations, radio-ulnar, mid- 
dle, 223 
superior, 223 
sacro-coccygeal, 228 
-iliac, 228 
scapho-cuneiform, 242 
-clavicular, 217 
sternal, 213 
sterno-clavicular, 216 
tarso-metatarsal, 243 
of tarsus, 240 
temporo-mandibular, 214 
of thorax, 211 
tibio-fibular, 237 
inferior, 238 
superior, 237 
transverse, 225 
interosseous, 418 
mediastinal, 425 
meningeal, 407 
perforating, 449 
scapular, 411 
spinal, 407 
temporal, 399 
tibial, 446 
recurrent, 451 
prevertebra!, 398 
princeps cervicis, 398 
pollicis, 422 
profunda feraoris, 443 
inferior, 416 
superior, 416 
pterygoid, 401 
pterygo-palatine, 401 
pubic, 489 
pudic, deep external, 443 
internal, 435 
superficial external, 443 
pulmonary, 379 
pyloric, 428 
radial, 421 
recurrent, 421 
radialis indicis, 422 
of trunk, 205 
of upper extremity, 216 
of vertebral column, 205 
Articularis genu muscle, 308 
Arytenoid cartilages, 768 
Aryteno-epiglottideus, 773 
Arytenoideus, 773 
Ascending colon, 729 
vena cava, 474 
Association fibres in cerebrum, 
520 
tracheal, 410 
transversalis colli, 411 
transverse facial, 398 
perineal, 436 
tympanic, 400 
ulnar, 417 
recurrent, 418 
Astragalus, 158 
Atlas, 116 
Atrium of right auricle, 367 
Attolens aurem, 678 
Attrahens aurem, 679 
Auditory area, 551 
meatus, external, 677 
nerve, 589, 674 
distribution in labyrinth, 672 
organ, development of, 108 
Auricle, left, of heart, 369 
right, 367 
atrium of, 367 
Auricular artery, 397 
anterior, 399 
posterior, 398 
nerve, posterior, 587 
of tenth, 594 
veins, anterior, 460 
posterior, 460 
Auricularis anterior, 679 
posterior, 679 
superior, 678 
Auriculotemporal nerve, 582 
Axilla, 415 
suspensory ligament of, 354 
Axillary artery, 412 
fascia, 353 
ranine. 396 
uterine, 434 
vaginal, 434 
vertebral, 406 
vesical, 434 
Vidian, 401 
Articular synovial membrane, 70 
Articulations, 203 
acromio-clavicular, 217 
of astragalus, 240 
between articular processes of 
vertebrae, 207 
receptacular, 402 
recurrent, anterior tibial, 451 
carpal. 423 
posterior tibial, 451 
radial, 421 
ulnar, 418 
renal, 431 
right colic, 430 
sacra media, 432 
sacral, lateral, 437 
scapular, posterior, 411 
sciatic, 436 
atlas and occipital bone, 210 
axis and atlas, 208 
and occipital bone, 209 
bodies of vertebrae, 205 
pisiform and cuneiform, 225 
calcaneo-cuboid, 241 
carpal, 225 
carpo-metacarpal, 226 
chondro-sternal, 212 
coraco-clavicular, 217 
costo-chondral, 212 
-vertebral, 211 
cubo-cuneiform, 242 
short ciliary, 402 
gastric, 429 
sigmoid, 431 
small meningeal, 400 
spermatic, 431 
spinal, 425 
anterior, 407 
lateral, 407 
posterior, 407 
splenic, 428 
spheno-palatine, 401 
sterno-rnastoid, 395, 397 
stylo-mastoid, 398 
subclavian, 404 
sublingual, 396 
submental, 397 
subscapular, 411, 415 
superficial cervical, 411 
circumflex iliac, 443 
epigastric, 443 
external pudic, 443 
perineal, 436 
superficialis volae, 422 
superior epigastric, 410 
hemorrhoidal, 431 
-scaphoid, 242 
of head, 205 
interchondral, 213 
intercoccygeal, 228 
intercuneiforrn, 242 
intermetacarpal, 226 
intermetatarsal, 244 
interphalangeal, 227, 244 
of lower limb, 230 
lymph-nodes, 492 
space, 415 
veins, 470 
Axis, 117 
cerebro-spinal, 499 
cceliac, 427 
thyroid, 410 
Azygos uvulae, 702 
veins, great, 471 
left lower, 472 
lower, left, 472 
right, 471 
small, 472 
medio-carpal, 225 
metacarpophalangeal, 227 
metatarso-phalangeal, 244 
of pelvis, 227 
with last lumbar vertebra, 
227 
intercostal, 411 
laryngeal, 395 
mesenteric, 429 
pancreatico-duodenalis, 428 
B. 
radio-carpal, 224 
-ulnar, 223 
Back, dissection of, 893 
fascia of, 358 
muscles of, 325 
inferior, 223 898 
INDEX. 
Band, ilio-tibial, 362 
moderator, 369 
Bartholin, glands of, 841 
Basal, commissure, gray, 535 
white, 518 
Basement membrane, 41 
Basilar artery, 408 
membrane, 670 
plexus, 466 
sinus, 466 
vein, 469 
median, 469 
Bone or bones, of lower limb, 146 
malar, 186 
maxillary, inferior, 187 
superior, 181 
metacarpal, 144 
of metatarsus, 161 
nasal, 185 
navicular, 160 
number of, 113 
occipital, 165 
os calcis, 159 
innorninatum, 146 
magnum, 143 
pubis, 149 
outward forms of, 113 
palate, 183 
parietal, 168 
patella, 154 
pelvic, 150 
phalanges of hand, 144 
of foot, 162 
pisiform, 143 
pyramidal, of carpus, 141 
radius, 139 
Breasts, 843 
Broad ligament of lung, 767 
of uterus, 832 
Broca, pouch of, 839 
Bronchi, 758 
Bronchia, 758 
Bronchial artery, 425 
lymph-nodes, 495 
tubes, 758 
veins, 472 
Bronchioles, 758 
Brunner, glands of, 723 
Buccal artery, 401 
glands, 699 
lymph-nodes, 490 
nerve, 588 
long, 582 
veins, 459 
Buccinator fascia, 350 
muscle, 346 
Bulb, arteries of, 4ST6 
of corpus spongiosum, 814 
of crus penis, 813 
end, 655 
olfactory, 567 
in posterior horn of lateral 
ventricle, 528 
spinal, 545 
Bulbi vestibuli, 841 
Bulbo-cavernosus muscle, 821,. 
842 
Bauchstiel, 83 
Bell, nerve of, 607 
Bellini, ducts of, 781 
Belly-stalk, 83 
Bertin, columns of, 781 
Biceps flexor cruris, 301 
cubiti, 263 
Bicuspid teeth, 703 
valve, 369 
Bile-ducts, 739, 746 
Biventer cervicis muscle, 330 
Bladder, false ligaments of, 787 
gall, 746 
ligaments of, 361 
trigonum of, 785 
urinary, 785 
development of, 102 
Blandin, gland of, 734 
Blastodermic vesicle, 80 
Blood, 57 
circulation of, 366 
islands, 83 
-vascular system, 365 
-vessels, development of, 93 
of lungs, 762 
physiological anatomy of, 
374 
ribs, 127 
sacrum, 120 
scaphoid, 141 
scapula, 133 
semilunar, 141 
sesamoid, 245 
sphenoid, 176 
sternum, 126 
of tarsus, 158 
temporal, 171 
tibia, 155 
trapezium, 143 
trapezoid, 143 
turbinate, inferior, 185 
tympanic, 175 
ulnar, 137 
of upper limb, 131 
unciform, 143 
vertebra prominens, 117 
vertebra, lumbar, 119 
peculiar, 118 
sacral, 120 
thoracic, 117 
vomer, 184 
Wormian, 190 
Bony cochlea, 673 
Borders of liver, 744 
Bowman, glands of, 667 
Brachial artery, 415 
fascia, 355 
plexus, 606 
Brachialis muscle, 264 
Brachio-cephalic artery, 386 
vein, 457 
-radialis muscle, 265 
Brachiura, anterior, 533 
posterior, 533 
Brain, 499 
arachnoid of, 560 
diagrammatic description of, 
506 
-urethral glands, 820 
Bundle of Yicq-d’ Azyr, 522 
Burdach, tract of, 556 
Bursa, pharyngeal, 710 
Bursal synovial membrane, 70 
c. 
Body-ciliary, 684 
Malpighian, of kidney, 780 
restiform, 546 
Cacumen, 543 
Cadaver, division of, 885 
Ctecurn, 727 
Calamus scriptorius, 547 
Calcanean artery, internal, 449* 
Calcaneo-plantar nerve, 634 
Calcaneum, 159 
Calcar, 528 
Calcarine fissure, 512 
Callosal fissure, 512 
Calloso-marginal fissure, 512 
Callosum, 517 
peduncles of, 520 
Calvaria, 196 
Canal or canals, alimentary, tu- 
nics of, 697 
thyroid, 796 
Wolffian, 99 
Bone or bones, 113 
astragalus, 158 
atlas, 116 
axis, 117 
calcaneum, 159 
carpal, 140 
clavicle, 131 
coccyx, 122 
composition of, 113 
cranium, 165 
cuboid, 159 
cuneiform, of carpus, 141 
of tarsus, 160 
development of, 113 
ethmoid, 179 
extremities, development of, 
93 
anal, 734 
central, of spinal cord, devel- 
opment of, 103 
of cochlea, 669 
of Corti, 672 
crural, 362 
femoral, 362 
of Gartner, 835 
development of, 100 
Plunter’s, 440 
lachrymal, 692 
of Nuck, 803 
of Petit, 689 
of Schlemm, 683 
semicircular, 669, 673 
spinal, 124 
Stenson’s, 666 
of Stilling, 689 
Canalis reunions, 670 
of face, 181 
femur, 151 
fibula, 157 
of foot, 158 
frontal, 169 
functions of, 113 
of hand, 140 
dura of, 558 
infundibulum of, 534 
membranes of, 558 
pia of, 560 
-sand, 535, 561 
veins of, 467 
ventricles of, development of, 
103 
of hip, 146 
humerus, 135 
hyoid, 189 
ilium, 146 
internal arrangement of, 113 
ischium, 148 
lachrymal, 186 
Branchial cleft, 85 
Breast, male, 845 
utriculo-saccularis, 669 INDEX. 
899 
Canine teeth, 703 
Canthi, 691 
Centrum, 115 
Cephalic vein, 470 
Choroid, 684 
anterior, 403 
Capsule, external, 537 
of Glisson, 744 
Cephalo-rachidian fluid, 500 
Cerebellar ala, 543 
fissure, 528 
plexuses, 526 
of fourth ventricle, 546 
veins, 468 
Chyle, 57 
Chyli, receptaculum, 487 
Cilia, 692 
Ciliary arteries, 686 
artery, anterior, 402 
long, 402 
short, 402 
internal, 537 
suprarenal, 798 
of Tenon, 680 
Caput coli, 727 
gallinaginis, 790 
Cardia of stomach, 716 
Cardiac nerves, 643, 644 
cervical, 595 
thoracic, 595 
plexus, 648 
veins, 455 
anterior, 456 
amygdala, 544 
arbor vitae, 542 
artery, posterior inferior, 408 
corpus dentatum, 544 
dorsal tuber, 544 
folia, 542 
lingula, 543 
nodule, 544 
peduncles, 542 
pyramid, 544 
trapezium, 542 
uvula, 544 
veins, inferior, 468 
superior, 468 
Cerebellum, 541 
development of, 104 
hemispheres of, 542 
Cerebral artery, anterior, 403 
middle, 403 
hemisphere, arteries of, 530 
peduncles, 538 
veins, anterior, 468 
deep, 468 
inferior, 468 
middle, 468 
body, 684 
ganglion, 577 
muscle, 684 
nerves, 686 
processes, 685 
zone, 684 
Ciliated epithelium, 43 
Cinereum, tuber, 534 
Circle of Willis, 408 
Circular fissure, 514 
sinus, 466 
Circulation of the blood, 366 
Circulus major iridis, 686 
Circumflex artery, anterior, 415 
external, 443 
internal, 443 
posterior, 415 
nerve, 613 
Circumvallate papillae, 660 
Cisternae arachnoidales, 561 
Clarke, column of, 554 
Classes of tissues, 41 
Claudius, cells of, 672 
Claustrum, 525 
Clavicle, 131 
Clavi-coraco-axillary fascia, 354 
Clavi-pectoral fascia, 354 
Clefts, branchial, 85, 87 
structures derived from, 87 
Clinical anatomy, 20 
Clitoris, 840 
development of, 102 
Clivus, 543 
Cloaca, 102 
Coccygeal artery, 437 
gland, 800 
nerves, 627, 639 
Coccygeus muscle, 821 
Coccyx, 122 
Cochlea, bony, 673 
canal of, 669 
Cceliac axis, 427 
great, 455 
middle, 456 
posterior, 456 
smallest, 456 
Carotid artery, external, 392 
internal, 401 
glands, 800 
plexus, 643 
Carpal arch, posterior, 420 
artery of radial, anterior, 422 
posterior, 422 
of ulnar, anterior, 420 
posterior, 420 
Cartilage, arytenoid, 768 
costal, 129 
cricoid, 768 
cuneiform, 771 
epiglottic, 769 
hyaline, 51 
Meckel’s, 92 
superficial, 467 
superior, 467 
Cerebro-spinal axis, 499 
cavity of, 501 
membranes of, 557 
walls of, 505 
fluid, 500 
nerve, typical, 563 
Cerebrum, 509 
surface of, 509 
Cerumen, 678 
Ceruminous glands, 678 
Cervical artery, ascending, 410 
deep, 411 
superficial, 411 
cardiac nerves, 595 
curve of spinal cord, 553 
enlargement of spinal cord, 553 
fascia, 351 
ganglion, inferior, 644 
middle, 644 
nasal, 664 
reticular, 52 
thyroid, 768 
true, 51 
white fibro-, 51 
yellow fibro-, 52 
Caruncnla lachrymalis, 692 
myrtiformes, 810 
Cauda equina, 557 
Caudate lobe, 743 
nucleus, 524 
Cavernous plexus, 643 
sinus, 466 
Cavities opening into nasal fos- 
sae, 666 
in sustentacular tissues, mem- 
brane lining, 69 
Cavity, abdominal, 713 
amniotic, 84 
of cerebro-spinal axis, 501 
membrane lining, 69 
general ventricular, 504 
nasal, 663 
Cavum oris, 699 
Cells, 37 
chalice, 44 
superior, 642 
lymph-nodes, deep, 489 
superficial, 490 
nerves, 603 
first, 602 
superficial, 605 
plexus, 603 
veins, deep, 463 
transverse, 460 
vertebra, 116 
Cervicalis ascendens, 329 
lymph-nodes, 497 
plexus, 646 
Coelom, 82 
Colic arterv, 430 
left, 430 
of Claudius, 672 
of Deiters, 672 
ethmoidal, 666 
goblet, 44 
Cervicofacial division of seventh 
nerve, 588 
Cervix of uterus, 830 
Chalice cells, 44 
Chamber, aqueous, 689 
Cheeks, 699 
Chiasrna, optic, 568 
Chink of glottis, 775 
Choanse, 663 
Chondroglossus, 710 
Chorda tyrnpani. 677 
Chordae tendinese, 369 
Chorio-capillaris, 684 
middle, 430 
right, 430 
Collar-bone, 131 
Collateral fissure, 513 
Colliculus seminalis, 790 
Colon, 728 
hepatic, 740 
mastoid, 675 
prickle, 43 
reproduction, 39 
Cement, 87 
Central canal of spinal cord, 554 
lobe, 511 
point of perineum, 820 
ascending, 729 
descending, 729 
sigmoid, 730 
transverse, 7 29 
Column of Clarke, 554 
lateral, of oblongata, 545 
muscle, 61 
vertebral, 115 
Centrosome, 78 
Chorion, 83, 84 
Columna nasi, 663 900 
INDEX. 
Columnse carneae, 368 
Columnar epithelium, 42 
Columns, anal, 734 
of Bertin, 781 
of spinal cord, 553 
Commissure, anterior, 522 
basal gray, 535 
white, 518 
middle, 533 
optic, 568 
posterior, 535 
of spinal cord, gray, 554 
white, 554 
Corpora quadrigemina, develop- 
ment of, 105 
Cutaneous membrane, 74 
nerve of anterior crural, in- 
Corpus Arantii, 368 
callosum, 518 
genu of, 518 
rostrum of, 518 
cavernosum, arteries of, 436 
dentatum, cerebellar, 544 
fimbriatum, 521 
Highmorianum, 804 
luteum, 826 
spongiosum, 814 
bulb of, 814 
striatum, 523 
subthalamicum, 536 
triticeum, 771 
Corpuscles, Malpighian, 794 
muscle, 61 
Pacinian, 655 
touch, 654 
Corrugator supercilii muscle, 347 
Corti, canal of, 672 
organ of, 671 
development of, 109 
rods of, 671 
Costal cartilages, 129 
Costo-colic ligament, 750 
-coracoid ligament, 354 
membrane, 354 
Cowper, glands of, 820 
Cranial cavity, floor of, 197 
nerves, 565 
ternal, 625 
middle, 624 
internal, 612 
perforating, 630 
small internal, 612 
of thigh, external, 624 
Cuticle, 652 
Cutis vera, 653 
Cystic duct, 746 
of vulva, anterior, 838 
posterior, 838 
Common bile duct, 746 
Communicans hvpoglossi nerve, 
597 
Communicating artery, anterior, 
403 
I). 
Dartos, 810 
Decidua reflexa, 84 
serotina, 84 
vera, 84 
Deciduous teeth, 703 
Decussation of pyrarpids, 545 
Deep fascia, 350 
lymph-vessels, 486 
temporal nerve, 581 
Deiters, cells of, 672 
Delimitations of surface parts, 21 
Deltoid fascia, 355 
Deltoideus muscle, 258 
Dental artery, inferior, 400 
nerve, inferior, 582 
shelf, 86 
Dentate gyrus, 517 
nucleus, 547 
Denticulate ligament, 562 
Dentine, 56 
Depressor alse nasi, 347 
anguli oris, 346 
labii inferioris, 346 
Derma, 653 
Descemet, membrane of, 682 
Descend ens hypoglossi nerve, 
597 
posterior, 403 
Comparative anatomy, 18 
Complexus muscle, 329 
Compressor naris muscle, 347 
nariurn minor, 347 
urethrae muscle, 822 
Conariurn, 535 
Concha, 678 
Conduction paths in spinal cord, 
554 
Cone, terminal, of spinal cord, 
553 
Coni vasculosi, 806 
Conjunctiva, 693 
fornix of, 694 
Connective tissue, 46 
Constrictor, inferior, 711 ' 
medius, 711 
superior, 711 
Coraco-brachialis muscle, 260 
Cord, spermatic, 812 
spinal, 499, 552 
arachnoid of, 562 
nuclei of, 569 
region, dissection of, 890 
Cranium, bones of, 165 
cerebral lobes in, 517 
inside of, dissection of, 891 
interior of, 196 
Cremaster of Henle, 812 
Cremasteric artery, 438 
fascia, 811 
Cribriform fascia, 362 
Cri co-ary tenoideus lateralis, 772 
posterior, 772 
■thyroid artery, 395 
-thyroideus, 771 
Cricoid cartilage, 768 
Crista acnstica, 669 
Descending colon, 729 
vena cava, 456 
of the abdomen, 474 
hepatic, 475 
phrenic, 475 
renal, 475 
suprarenal, 475 
Development of arteries, 95 
of blood-vessels, 93 
of bones, 113 
central canal of, 554 
cervical curve of, 553 
enlargement of, 553 
conduction paths in, 554 
dura of, 561 
gray commissure of, 554 
length of, 553 
lumbar enlargement of, 553 
pia of, 561 
terminal cone of, 553 
vestibuli, 673 
Cross-striped muscular tissue, 59 
Crura cerebri, 538 
penis, 813 
Crural arch, deep, 360 
canal, 362 
of extremities, 93 
of canals of Gartner, 100 
thoracic curve of, 553 
weight of, 553 
white commissure of, 554 
umbilical, 83 
vocal, false, 770 
true, 770 
Coriurn, 653 
Cornea, 682 
Corniculum laryngis, 769 
Corona ciliaris, 685 
glandis, 815 
radiata, 537 
Coronary ligament of liver, 745 
plexus, 649 
sinus, 455, 466 
- veins, 455 
right, 456 
small, 456 
Corpora albicantia, 522, 534 
cavernosa, 813 
geniculata, 533 
quadrigemina, 538 
of central canal of spinal cord, 
103 
Crusta, 539 
Crypts of Lieberkiihn, 720 
Cuboid bone, 159 
Cucullaris muscle, 253 
Cul-de-sac of Douglas, 831 
Culmen, 543 
Cuneiform bone of the carpus, 
141 
nerve, anterior, 624 
sheath, 359 
of cerebellum, 104 
of clitoris, 102 
of cloaca, 102 
of corpora quadrigemina, 105 
of diaphragm, 97 
of ear, 108 
early stages of, 79 
of enamel, 86 
external, 161 
internal, 160 
middle, 161 
of tarsus, 160 
cartilage, 771 
Cuneus, 516 
Cupola, 674 
Curve, cervical, of spinal cord, 
553 
of epencephalon, 104 
of epididymis, 101 
of excretory organs, 98 
of eye, 107 
of eyelids, 108 
of Fallopian tubes, 100 
of gubernaculum, 102 
of the gustatory organs, 106 
of heart, 93 . 
of hydatid of Morgagni, 100 
of insula, 106 
of intestines, 88 
thoracic, of spinal cord, 553 
Cushion of epiglottis, 775 INDEX. 
901 
Development of labia majora, 
103 
Dilatator naris, posterior, 347 
Diploe, veins of, 463 
Discus proligerus, 824 
Dissection of abdomen and lower 
Ducts, pancreatic, 737 
of Stenson, 735 
minora, 103 
of lachrymal duct, 108 
glands, 108 
of liver, 90 
of lungs, 88 
of lymphatic vessels, 98 
of medulla oblongata, 104 
of mesenteries, 88 
of metencephalon, 104 
of muscular system, 98 
of nervous system, 103 
of neuroglia, 103 
of oblongata, 104 
of olfactory organs, 106 
of optic thalamus, 105 
of organ of Corti, 109 
of Giraldes, 101 
thoracic, 487 
of Wharton, 736 
Wolffian, 98 
Ductus arteriosus, 96, 380 
cochlearis, 670 
limb, 887 
of abdominal cavity, 888 
walls, 887 
of back, 893 
of arm, 887 
of hand,BB7 
communis choledochus, 746 
endolymphaticus, 669 
venosus fissure, 743 
Duodenal glands, 723 
Duodenum, 721 
Dura mater of brain, 558 
of spinal cord, 561 
of hip, 890 
of leg, 890 
of neck, 891 
of thigh, 890 
of thorax and upper limb, 
887 
E. 
of cranial region, 890 
of deep parts of the neck, 892 
of face, 892 
of female perineum, 889 
of front of arm, 886 
of forearm, 886 
Ear, 668 
development of, 108 
drum of, 674 
external, 677 
internal, 668 
labyrinth of, 668 
middle, 674 
Ectoderm, 80 
organs derived from, 103 
Eighth nerve, 589 
Ejaculatory ducts, 809 
Elastic tissues, 47 
Elbow-joint, 221 
Elementary tissues, 37 
Eleventh nerve, 596 
of ovaries, 99 
of pancreas, 91 
of paroophoron, 100 
of parovarium, 100 
of penis, 102 
of perineum, 102 
of placenta, 83, 85 
of pons, 104 
of prosencephalon, 105 
of quadrigemina, 105 
of reproductive organs, 98 
of rhinencephalon, 106 
of ribs, 92 
of round ligament, 100 
of scrotum, 102 
of sinus pocularis, 101 
of skeleton, 91 
of skull, 92 
of spleen, 98 
of sternum, 127 
of stomach, 90 
of suprarenal bodies, 98 
of the sympathetic system, 106 
of the tactile organs, 106 
of teeth, 86 
of leg and dorsum of foot, 
889 
of thigh, 889 
of head and neck, 890 
of inner side of thigh, 889 
of inside of cranium, 891 
of male perineum, 888 
of mandibular region, 892 
of orbit, 892 
of outer side of leg, 889 
of palm, 886 
of pelvic cavity of female, 888 
of male, 888 
of prevertebral region, 892 
of side of neck, 891 
of sole, 890 
of temporal and zygomatic 
fossae, 892 
of thoracic cavity, 886 
of thorax and upper limb, 886 
Distribution of spinal nerves, 
mode of, 600 
nuclei of, 590 
Embryology, 77 
Embryonic area, 82 
shield, 80 
Eminentia collateralis, 528 
teres, 540, 551 
Emissary veins, 463 
Enamel, development of, 86 
organ, 86 
second, 87 
Encephalic vesicles, 500 
Encephalon, 499 
weight of, 552 
End bulbs, 655 
Endocardium, 366 
of testes, 100 
of thalamencephalon, 105 
of thymus, 88 
of thyroid gland, 88 
of tongue, 88 
of trachea, 88 
of tunica vaginalis, 101 
of urachus, 102 
Division of cadaver, 885 
Divisions, anterior primary, of 
spinal nerves, 603 
dorsal primary, of first cervi- 
cal nerve, 602 
of spinal nerves, 601 
Dorsal artery of penis, 436 
nerve of penis, 631 
pyramid, 546 
tuber, cerebellar, 544 
veins of penis, 480 
Dorsalis hallucis artery, 453 
pedis artery, 452 
Dorsum of foot, dissection of, 889 
Douglas, cul-de-sac of, 831 
folds of, 831 
Drum of ear, 674 
Ductless glands, 793 
Ducts of Bellini, 781 
bile, 746 
common, 746 
cystic, 746 
ejaculatory, 809 
hepatic, 746 
lachrymal, development of, 
108 
Endoderrn, 80 
organs derived from, 86 
Endomysium, 61 
Endoneurium, 64 
Endosteum, 53 
Endothelium, 41 
End-plate, motorial, 65 
Endyma, 500 
Enlargement, of spinal cord, 
cervical, 553 
of ureters, 99, 102 
of urethra, 102 
of urinary bladder, 102 
of urogenital sinus, 102 
of uterus, 100 
masculinus, 101 
of vagina, 100, 103 
of vas deferens, 101 
of veins, 96 
of ventricles of brain, 103 
of vertebra, 91 
Diaphragm, development of, 97 
of sella, 559 
Diaphragrna muscle, 334 
Diaphragmatic plexus, 646 
Diaphysis, 114 
Diarthrosis, 204 
Digastric lobe, 544 
Digestion, organs of, 695 
Digital arteries of ulnar, 420 
fossa, 802 
nerves of foot, 635 
Dilatator naris, anterior, 347 
lumbar, 553 
Ensiform' process, 126 
Epencephalon, 540 
development of, 104 
Ependyma, 500 
Epicardium, 374 
Epicondylar lymph-nodes, 493 
Epidermis, 652 
Epididymis, 802, 805 
canal of, 806 
development of, 101 
Epidural space, 561 
Epigastric artery, deep, 438 
superficial, 443 
superior, 410 
plexus, 649 
veins, superficial, 481 
Epiglottic cartilage, 769 
of liver, 739 
lymphatic, left, 487 
right, 487 
Mullerian, 99 
nasal, 666, 694 902 
INDEX. 
Epimysium, 61 
Epineurium, 64 
Epiphyses, 114, 535 
Epithelium, 41 
ciliated, 43 
columnar, 42 
flattened, 42 
Face, coronary artery of, 397 
Facial artery, 396 
transverse, 398 
nerve, 585 
region of skull, 194 
vein, 457 
anterior, 457 
Fascia or fasciae, of shoulder, 354 
subscapular, 355 
superficial, 349 
supraspinous, 355 
temporal, 350 
thoracic, 353 
transversalis, 359 
vertebral, 358 
glandular, 44 
neuro-, 43 
pigmented, 43 
prickle cell of, 43 
sensory, 43 
simple, 44 
stratified, 44 
transitional, 44 
common, 458 
deep, 459 
posterior, 459 
transverse, 460 
Falciform ligament of liver, 745 
lobe, 513 
process, 362 
Fallopian tubes, 827 
development of, 100 
fimbriae of, 828 
fimbriated extremity of, 827 
Fallopius, aqueduct of, 174 
False ligaments of bladder, 787 
ribs, 127 
vertebrae, 115 
vocal cords, 770 
Fasciculus cuneatus, 547 
gracilis, 547 
solitary, 648 
Fatty tissues, 49 
Fauces, isthmus of, 700 
Female perineum, dissection of, 
889 
Epoophoron, 835 
Erector penis muscle, 821 
spinse, 327 
Eruption of teeth, 703 
Ethmoid bone, 179 
Ethmoidal artery, 402 
anterior, 402 
cells, 666 
Eustachian tube, 676 
valve, 368 
Excretory organs, development 
of, 98 
Expression, muscles of, 343 
Extensor brevis digitorum, 319 
pollicis, 282 
carpi radialis brevis, 270 
longus, 269 
ulnaris, 270 
communis digitorum, 277 
indicis, 278 
longus digitorum, 319 
hallucis, 319 
pollicis, 282 
minimi digiti, 278 
ossis metacarpi pollicis, 282 
prirai internodii pollicis, 282 
proprius hallucis, 319 
secundi internodii pollicis, 282 
External anterior thoracic nerve, 
608 
Femoral artery, 439 
canal, 362 
ring, 360 
sheath, 359 
veins, 482 
Femur, 151 
Fenestra ovalis, 673, 675 
rotunda, 674, 675 
Ferrein, pyramids of, 780 
Fibres, association, 520 
of Sharpey, 54 
Fibro-cartilage, white, 51 
yellow, 52 
Fibrous tissues, white, 46 
yellow, 47 
tunic of eye, 683 
Fibula, 15? 
Fibnlar nerve, 634 
Fifth nerve, 574 
ophthalmic division of, 575 
sacral, 639 
Falx cerebelli, 559 
cerebri, 559 
Fascia or fasciae, 349 
of the abdominal cavity, 359 
of the arm, 355 
axillary, 353 
of the back, 358 
brachial, 355 
buccinator, 350 
cervical, 351 
inner, 352 
middle, 352 
outer, 351 
clavi-coraco-axillary, 354 
-pectoral, 354 
cremasteric, 810 
cribriform, 362 
deep, 350 
transverse, 363 
deltoid, 355 
dentata, 517 
dorsal, of hand, 357 
external spermatic, 810 
of foot, 364 
Filiform 661 
Fillet, 550 
Filuin terminale, 553 
Fimbria, 521 
ovarian, 824, 828 
Fimbriae of Fallopian tube, 828 
Fimbriated extremity of fallo- 
pian tube, 827 
Fingers, muscles moving, 272 
First nerve, 567 
auditory meatus, 677 
capsule, 537 
cutaneous nerve of musculo- 
cervical, 602 
Fissure, calcarine, 512 
callosal, 512 
calloso-marginal, 512 
central, 510, 512 
spiral, 615 
of thigh, 624 
ear, 677 
laryngeal nerve, 594 
medullary lamina, 525 
os, 830, 831 
palatine nerve, 580 
plantar nerve, 635 
popliteal nerve, 636 
pterygoid nerve, 582 
respiratory nerve, 607 
spermatic fascia, 810 
superficial petrosal nerve, 587 
Extraspinal veins, 472 
Extremities of liver, 744 
Eye, 680 
appendages of, 691 
development of, 107 
Eyeball, muscles of, 690 
Eyelashes, 692 
Eyelids, 691 
of forearm, 355 
of hand, 356 
of head, 350 
of hip and thigh, 362 
iliac, 360 
infraspinous, 355 
infundibuliform, 360, 811 
intercolumnar, 810 
intercostal, 354 
external, 354 
choroid, 528 
circular, 514 
collateral, 513 
ductus venosus, 743 
gall-bladder. 742 
of Glaser, 172 
hippocampal, 517 
intraparietal, 515 
longitudinal, of cerebrum, 510 
olfactory, 515 
parallel, 516 
parietooccipital, 511, 512 
portal, 742 
precentral, 514 
precuneal, 513 
pterygo-maxillary, 191 
Eolandic, 510 
internal, 354 
spermatic, 811 
lata, 362 
of leg, 362 
lumbar, 358 
masseteric, 350 
middle spermatic, 811 
obturator, 360 
palmar, 356 
parotid, 350 
pectoral, 353 
pelvic, 360 
development of, 108 
of perineum, 361 
plantar, 364 
prevertebral, 352 
propria, 811 
pyriformis, 361 
recto-vesical, 361 
spheno-maxillary, 192 
of spinal cord, 553 
supraorbital, 515 
Sylvian, 510 
transverse, 528, 742 
umbilical, 742 
vena caval, 743 
Face, bones of, 181 
dissection of, 892 
F. INDEX. 
903 
Flattened epithelium, 42 
Flexor accessorius, 317 
brevis digitorum, 317 
hallucis, 317 
minimi digiti, 275 
pedis, 317 
pollicis, 282 
carpi radialis, 269 
ulnaris, 269 
longus digitorum, 317 
hallucis, 316 
pollicis, 282 
ossis rnetacarpi minimi digiti, 
275 
Fourth nerve, 574 
sacral, 638 
ventricle, 550 
Fovea centralis, 687 
hemielliptica, 673 
hemispherica, 673 
inferior, 551 
superior, 540, 551 
Frfenum labii, 699 
linguae, 708 
preputii, 815 
Framework organs, 32 
Frenulum, 543 
Frontal artery, 403 
bone, 169 
gyri, 514 
lobe, 511, 513 
nerve, 576 
sinuses, 666 
veins, 459, 463 
Frontalis muscle, 348 
Fronto-nasal process, 86 
Fundus of uterus, 830 
Fungiform papillae, 661 
Furrow, spinal, 124 
Geniculate ganglion, 585 
Genioglossus, 709 
Genio-hyoideus muscle, 339 
Genito-crural nerve, 624 
Genu of callosum, 518 
Germinal epithelium, 825 
spot, 826 
vesicle, 826 
Gimbernat’s ligament, 332 
Gingivae, 707 
Giraldes, organ of, 807, 835 
development of, 101 
Gladiolus, 126 
Gland or glands, 75 
agminated, 724 
of Bartholin, 841 
of Blandin, 734 
of Bowman, 667 
of Brunner, 723 
buccal, 699 
bulbo-urethral, 820 
carotid, 800 
ceruminous, 678 
coccygeal, 800 
of Cowper, 820 
ductless, 793 
duodenal, 723 
intestinal, 720 
pollicis, 281 
perforans muscle, 274 
perforatus digitorum pedis, 
317 
muscle, 273 
profundus digitorum, 274 
sublirnis digitorum, 273 
Flexure, hepatic, 729 
splenic, 729 
Flocculus, 544 
Fluid, cephalo-rachidian, 500 
cerebro-spinal, 500 
Fold, amniotic, 83 
of Douglas, 831 
Folia, cerebellar, 542 
Follicle, Graafian, 824 
hair, 657 
Fontana, spaces of, 683 
Fontanelles, 190 
Foot, bones of, 158 
dorsujp of, dissection of, 889 
fascise of, 364 
muscle moving the whole, 308 
phalanges of, 162 
as a whole, 163 
Foramen csecum of oblongata, 
545 
Gr. 
Galactophorous ducts, 844 
Galen, veins of, 456, 468 
Gall-bladder, 746 
fissure, 742 
Ganglia of the hemisphere, 522 
of nerves, 65 
sporadic, of fifth nerve, 576 
Gangliated cord, lumbar portion 
of, 646 
thoracic portion of, 644 
Ganglion, aortico-renal, 649 
cervical, inferior, 644 
middle, 644 
superior, 642 
ciliary, 577 
Gasserian, 574 
geniculate, 585 
impar, 648 
jugular, 591 
lenticular, 577 
mesenteric, superior, 649 
ophthalmic, 577 
otic, 584 
petrous, 591 
semilunar, 574 
of sympathetic, 649 
spiral, 674 
submandibular, 583 
labial, 699 
lachrymal, 684 
development of, 108 
mammary, 843 
Meibomian, 692 
molar, 699 
palatine, 700 
parotid, 735 
periurethral, 841 
pineal, 535 
pituitary, 534 
prostate, 818 
salivary, 734 
development of, 86, 87 
sebaceous, 658 
of tongue, 707 
epiploicum, 751 
of Magendie, 505, 547 
of Monro, 535 
obturator, 149 
solitary, 720 
sublingual, 736 
submaxi 11 ary, 735 
suburethral, 820 
sweat, 659 
ovale, 367 
of Winslow, 751 
Foramina Thebesii, 367 
Forceps, anterior, 519 
posterior, 519 
Forearm, fascia of, 355 
muscles moving outer part of, 
266 
thyroid, 796 
urethral, 841 
vulvo-vaginal, 841 
of Weber, 734 
Glandulse odoriferse, 815 
Pacchionii, 561 
vestibulares majores, 841 
minores, 841 
Glandular artery, 397 
epithelium, 44 
Gians penis, 814 
Glaser, fissure of, 172 
Glisson, capsule of, 744 
Globus major, 802 
minor, 802 
whole, 263 
Forehead, muscles of, 347 
Foreskin, 815 
Form of liver, 740 
Fornix, 520 
of conjunctiva, 694 
Fossa of antihelix, 678 
digital, 802 
of helix, 678 
submaxillary, 583 
Gartner, canals of, 835 
development of, 100 
Gasserian ganglion, 574 
Gastric artery, 427 
short, 429 
veins, 479 
Gastrocnemius muscle, 309 
Gastro-colic omentum, 751 
-duodenalis artery, 428 
-epiploi’ca dextra artery, 428 
sinistra artery, 429 
Gelatinous tissues, 50 
Gemellus muscle, inferior, 301 
superior, 298 
Generation, organs of, 801 
female, 822 
male, 801 
ischio-rectal, 361 
nasal, 195, 664 
navicular, 840 
navicularis of urethra, 790 
ovalis, 367 
pallidus, 525 
Glossopharyngeal nerve, 591 
Glottis, chink of, 767, 775 
Gluteal artery, 437 
lines, 147 
lymph-nodes, 494 
nerve, inferior, 629 
superior, 629 
veins, 480 
Gluteus maximus muscle, 291 
medius muscle, 292 
minimus muscle, 292 
patellaris, 689 
spheno-maxillary, 191, 192 
temporal, 191 
dissection of, 892 
zygomatic, 191 
dissection of, 892 
Fourchette, 838 
Geniculate, corpora, 533 904 
INDEX. 
Goblet cells, 44 
Goll, tract of, 556 
Gowers, tract of, 555 
Graafian follicles, 824 
Gracilis muscle, 297 
Gray commissure, basal, 535 
of spinal cord, 554 
matter of spinal cord, 553 
Great deep petrosal nerve, 580 
occipital nerve, 602 
omentum, 751 
sciatic nerve, 631 
splanchnic nerve, 645 
superficial petrosal nerve, 580, 
587 
Groove, lateral, of mesencepha- 
lon, 539 
vertebral, 124 
Gross anatomy, 18 
of lungs, 762 
features of kidney, 781 
Gubernaculurn, 102 
testis, 802 
Gullet, 712 
Gums, 707 
Gustatory organs, development 
of, 106 
Gyri, frontal, 514 
limbic, 516 
occipital, 516 
operti, 512 
parietal, 515 
temporal, 516 
Gyrus, angular, 516 
dentate, 517 
Heart, veins of, 455 
Helicine arteries, 817 
Helicotrema, 674 
Iliac veins, common, left, 476 
right, 476 
external, 477 
internal, 479 
Helix, 678 
fossa of, 678 
Hemispheres of cerebellum, 542 
Hemorrhoidal artery, inferior, 
436 
superficial circumflex, 481 
Iliacus muscle, 291 
Ilio-costalis muscle, 327 
Iliohypogastric nerve, 623 
Ilio-inguinal nerve, 624 
-lumbar artery, 437 
veins, 476 
-psoas muscle, 291 
-tibial band, 362 
Ilium, 146 
Incisor teeth, 702 
Incus, 676 
Inferior cervical ganglion, 644 
dental nerve, 582 
fovea, 551 
middle, 434 
superior, 431 
nerve, inferior, 631 
plexus, 480, 648 
Henle, cremaster of, 812 
layer of, 657 
Hepatic arterv, 427, 735 
cells, 740 
duct, 746 
flexure, 729 
veins, 740 
Hepato-duodenal ligament, 750 
Herophilus, torcular of, 166, 
464 
gluteal nerve, 629 
hemorrhoidal nerve, 631 
laryngeal nerve, 594 
maxillary division of fifth 
nerve, 580 
mesenteric plexus, 647 
palpebral nerve, 579 
petrosal sinus, 461 
pudendal nerve, 630 
vena cava. 474 
Hiatus semilunaris, 666 
Highmore, antrum of, 183 
Hilum of kidney, 782 
of liver, 742 
of lung, 763 
Hip, back of, dissection of, 890 
-bone, 146 
fascia of, 362 
-joint, 230 
Hippocampal gyrus, 516 
Hippocampus major, 529 
minor, 528 
Histology, 19 
Homologies of bones of the 
limbs, 164 
Horn of lateral ventricle, mid- 
dle, 528 
vermis, 543 
Infracostales muscles, 336 
Inframandibular nerve, 588 
Infraorbital artery, 401 
nerve, 579 
of seventh, 588 
Infraspinatus muscle, 26l 
Infraspinous fascia, 355 
Infratrochlear nerve, 576 
Infundibula of ureter, 784 
Infundibuliform fascia, 360, 811 
Infundibulum of brain, 534 
of heart, 368 
of lung, 759 
of nose, 666 
hippocampal, 516 
marginal, 515 
paracentral, 515 
postcentral, 516 
precentx-al, 515 
subcalcarine, 516 
subcollateral, 516 
superior parietal, 516 
supramarginal, 516 
uncinate, 517 
posterior, 528 
Horny layer, 653 
Huguier, arterial circle of, 834 
Humerus, the, 135 
Humor, aqueous, 689 
vitreous, 689 
Hunter, canal of, 440 
Huxley, layer of, 657 
Hyaline cartilage, 51 
Hyaloid membrane, 689 
Hyaloplasm, 38 
Hydatid of Morgagni, 806, 835 
development of, 100 
Hymen, 840 
Hyoglossus, 709 
Hvoid artery, 395, 396 
bone, 189 
Hypogastric plexus, 647 
Hypoglossal area, 551 
nerve, 597 
Inguinal ligament, 332 
lymph-nodes, deep, 494 
superficial, 493 
Innominate veins, 457 
Insula, 511, 513 
development of, 106 
Intercavernous sinus, 466 
Interclavicular notch, 127 
Intercolumnar fascia, 810 
Intercostal artery, 425 
anterior, 409 
superior, 411 
fascia, 354 
external, 354 
interna], 354 
11. 
Hair follicle, 657 
papilla, 658 
Hairs, 656 
Hand, back of, dissection of, 887 
bones of, 140 
fascia of, 356 
muscles moving whole, 269 
phalanges of, 144 
Hard palate, 699 
Haustrum, 726 
Haversian system, 53 
Head, articulations of, 205 
fascia of, 350 
lymph-nodes of, 489 
muscles of, 341 
and neck, dissection of, 890 
veins of, 457 
Heart, 365 
apex of, 373 
auricle of left, 367 
development of, 93 
external configuration of, 371 
grooves of, 371 
infundibulum of, 368 
surfaces of, 371 
thickness of walls of, 367 
tissues of, 366 
Hypophysis, 534 
lymph-nodes, 495 
nerves, 619 
veins, 472 
superior, 471 
Intercostales externi muscle, 336 
intern! muscle, 336 
Interdeferential triangle, 808 
Interlabial space, 839 
Interlobular veins, 740 
Internal anterior thoracic nerve, 
608 
I. 
Ideal lobe of kidney, 778 
Ileo-caecal valve, 727 
-colic valve, 727 
artery, 430 
Iliac artery, common, 432 
deep circumflex, 439 
external, 438 
internal, 433 
superficial circumflex, 443 
fascia, 360 
lympb-nodes, external, 497 
internal, 497 
capsule, 537 
cutaneous nerve, 612 
of anterior crural, 625 
of musculo-spiral, 615 
laryngeal nerve, 594 INDEX. 
905 
Internal medullary lamina, 525 
os, 829, 831 
plantar nerve, 634 
popliteal nerve, 632 
saphenous nerve, 625 
secretion, organs of, 32 
spermatic fascia, 811 
sphincter, 734 
of urethra, 788, 792 
structure of oblongata, 547 
Interossei dorsales pedis, 322 
manus, 278 
palmares, 280 
plantares, 323 
volares muscle, 280 
Interosseous artery, anterior, 418 
posterior, 418 
of radial, 422 
of ulnar, 418 
membrane, 238 
nerve, anterior, 610 
posterior, 616 
Interpeduncular space, 534 
Interspinales muscles, 330 
Intertransversales muscles, 330 
Interventricular vein, posterior, 
456 
Kidneys, gross features of, 781 
hilum of, 782 
labyrinth of, 780 
lobes of, 778 
sinus of, 781 
situation of, 784 
Least splanchnic nerve, 646 
Left lobe of liver, 742 
Leg, back of, dissection of, 890 
fascia of, 362 
front of, dissection of, 889 
muscles moving, 301 
outer side of, dissection, of, 889 
Lemniscus, 539, 550 
Lens, 689 
vessels of, 780 
Knee-joint, 233 
Krause, membrane of, 60 
Jj. 
suspensory ligament of, 689 
Lenticular ganglion, 577 
nucleus, 525 
Leucocytes, 57 
Levator anguli oris, 346 
ani muscle, 821, 842 
labii inferioris, 346 
superioris ateque nasi, 346 
proprins, 346 
palati, 701 
palpebrse superioris, 691 
proprius ate nasi anterior, 347 
posterior, 347 
scapute, 254 
Levatores costarum muscle, 335 
Lieberkiihn, crypts of, 720 
Lienculi, 795 
Lieno-pancreatic ligament, 750 
-renal ligament, 750 
Ligament or ligaments, annular, 
of ankle, anterior, 363 
external, 363 
internal, 363 
of axilla, suspensory, 354 
of bladder, false, 787 
true, 361 
of carpus, anterior, 356 
costo-colic, 750 
Labia majora, 838 
development of, 103 
minora, 839 
development of, 103 
Labial artery, inferior, 397 
glands, 699 
nerve, superior, 579 
Labyrinth of ear, 668 
of kidney, 780 
membranous, 668 
Lachrymal artery, 402 
bone, 186 
canal, 692 
duct, development of, 108 
gland, 694 
development of, 108 
nerve, 576 
Intestinal artery, 430 
glands, 720 
Intestine, large, 724 
tunics of, 725 
small, 717 
tunics of, 718 
Intestines, development of, 88 
Intestinum tenue, 717 
sac, 692 
Lactiferous ducts, 844 
Lacuna rnagna, 792 
Lacunae of urethra, 791 
Lacunar ligament, 332 
Lamina cinerea, 535 
cribrosa, 682 
external medullary, 525 
internal medullary, 525 
quadrigemina, 539 
reticular, 672 
spiralis, 673 
terminate, 535 
vitreous, 684 
Intralobular veins, 740 
Intraparietal fissure, 515 
Intraspin al veins, 472 
Introitus vaginre, 840 
Iris, 685 
Ischio-cavernosus muscle, 821, 
842 
-coracoid, 354 
of forearm, posterior, 356 
Gimbernat’s, 332 
hepato-dnodenal, 750 
inguinal, 332 
lacunar, 332 
of larynx, 769 
of lens, suspensory, 689 
lieno-pancreatic, 750 
-renal, 750 
of liver, coronary, 745 
falciform, 745 
lateral, 745 
round, 745 
suspensory, 745 
lumbo-ovarian, 824 
palpebral, 693 
peritoneal, 750 
phreno-colic, 750 
-splenic, 794 
Poupart’s, 332 
round, development of, 100 
of scapula, 218 
scrotal, 801 
spiral, 674 
stylo-mandibular, 350, 352 
superficial transverse, 357 
suspensory of ovary, 824 
of penis, 816 
tubo-ovarian, 824 
uniting neural arches, 207 
of urethra, triangular, 361 
utero-ovarian, 823 
of uterus, anterior, 832 
-rectal fossa, 361 
Ischium, 148 
Island of Eeil, 511 
Islands, blood, 83 
substance, 83 
Isthmus cerebri, 538 
of fauces, 700 
Lanugo, 656 
Large intestine, 724 
tunics of, 725 
Laryngeal artery, inferior, 410 
superior, 395 
nerve, external, 594 
inferior, 594 
recurrent, 594 
of thyroid, 796 
J. 
superior, 594 
pouch, 773 
Laryngo-pharynx, 710 
Larynx, 767 
cartilages of, 768 
ligaments of, 769 
lining of, 773 
muscles of, 771 
ventricle of, 773 
Lateral column of oblongata, 
545 
Jacobson, nerve of, 591 
organ of, 666, 667 
Jejuno-ileum, 723 
Jelly, Whartonian, 83 
Joint, elbow-, 221 
kinds of, 204 
shoulder-, 218 
Jugular ganglion, 591 
nerve, 643 
sinus, 461 
veins, anterior, 460 
external, 460 
posterior, 460 
posterior external, 460 
internal, 461 
Juice canals, 484 
channels, 484 
groove of mesencephalon, 539 
ligaments of liver, 745 
nasal nerve, 579 
sinus, 464 
tract of oblongata, 545 
ventricle, horn of, middle, 
528 
posterior, 528 
Latissimus muscle, 261 
K. 
Layer of Henle, 657 
horny, 653 
of Huxley, 657 
Malpighian, 652 
broad, 832 
recto-vaginal, 832 
round,B32 
utero-sacral, 832 
Karyokinesis, 39 
Kidneys, 777 906 
INDEX. 
Ligament or ligaments, vaginal, 
of hand, 357 
of Zinn, 690 
Ligamentum denticulatum, 562 
infundibulo - pelvicum, 824, 
832 
Long saphenous nerve, 625 
Longissimus dorsi muscle, 329 
Longitudinal fissure of cere- 
brum, 510 
sinus, inferior, 464 
Lymph-node or lymph-nodes, 
parotid, 492 
pectoral, 493 
popliteal, 494 
posterior mediastinal, 495 
postpharyngeal, 492 
rectal, 497 
sacral, 497 
sternal, 495 
subclavian, 493 
submaxillary, 490 
suboccipital, 490 
subscapular, 493 
superficial cervical, 490 
inguinal, 493 
superior mediastinal, 495 
suprahyoid, 490 
of thorax, 495 
of upper limb, 492 
vena-caval, 497 / 
Lymph-nodules, aggregated, 724 
solitary, 720 
Lymph-vessels, 484 
deep, 486 
structure of, 485 
superficial, 485 
Lyra, 521 
pectinatum i rid is, 682 
Ligula, 547 
Limb, lower, articulations of, 230 
bones of, 146 
upper, articulations of, 216 
bones of, 131 
classification of muscles of, 
252 
superior, 463 
Longus colli muscle, 341 
Lubbe, veins of, 468 
Lumbar artery, 431 
enlargement of spinal cord, 
553 
fascia, 358 
lymph-nodes, lateral, 497 
median, 497 
movements of, 251 
Limbic gyri, 516 
lobe, 513 
Limbus, 674 
Line, white, 361 
Lines, gluteal, 147 
Lingua, 707 
Lingual artery, 395 
dorsal, 396 
lymph-nodes, 492 
nerve of ninth, 591 
of seventh, 587 
nerves, 622 
plexus, 622 
portion of gangliated cord, 646 
veins, 475 
ascending, 476 
Lumbo-ovarian ligament, 824 
Lumbricales manus, 276 
pedis, 318 
Lungs, blood-vessels of, 762 
broad ligament of, 767 
development of, 88 
gross anatomy of, 762 
hilum of, 763 
infundibulum of, 759 
minute anatomy of, 759 
Lunula, 656 
Lymph, 57 
Lyrnphadenoid structures, 487 
tissue, 487 
diffuse, 487 
Lymphatic duct, left, 487 
right, 487 
system, 484 
vessels, development of, 98 
Lymph-chambers, 485 
Lymph-node or lymph-nodes, 
487 
of vagus, 597 
Lingualis, 70S 
Lingula, cerebellar, 543 
Lining of the larynx, 773 
Lips, 699 
Liquid tissues, 57 
Liquor folliculi, 824 
Liver, 738 
borders of, 744 
broad ligament of, 745 
development of, 90 
extremities, 744 
Macroscopic anatomy, 18 
Macula acustica, 668, 669 
folliculi, 826 
M. 
lutea, 687 
Magendie, foramen of, 505, 547 
Magnum, os, 143 
Malar bone, 186 
of seventh nerve, 588 
Male perineum, dissection of, 
888 
form of, 740 
liilum of, 742 
lobule of, 738 
relations of, 747 
situation of, 747 
size of, 747 
surfaces of, 741 
tunics of, 744 
vessels of, 739, 745 
weight of, 747 
Lobe or lobes, central, 511 
digastric, 544 
on external cerebral surface. 
511 
muscles of, 820 
Malleus, 676 
Malpighian body of kidney, 780 
corpuscles, 794 
layer, 653 
Mammae, 843 
supernumerary, 845 
Mammary artery, internal, 409 
glands, 843 
veins, internal, 470 
Mandible, 187 
Mandibular division of fifth 
of abdomen, 497 
anterior mediastinal, 495 
axillary proper, 492 
bronchial, 495 
buccal, 490 
cervical, deep, 489 
superficial, 490 
cceliac, 497 
deep cervical, 489 
inguinal, 494 
epicondylar, 493 
external iliac, 497 
gluteal, 494 
of head and neck, 489 
iliac, external, 497 
internal, 497 
inguinal, deep, 494 
superficial, 493 
intercostal, 495 
internal iliac, 497 
maxillary, 492 
latei’al lumbar, 497 
lingual, 492 
of the lower limb, 493 
lumbar, lateral, 497 
nerve, 580 
process, 86 
region, dissection of, 892 
Manubrium, 126 
Marginal gyrus, 515 
veins, left, 456 
right, 456 
Marrow, 53, 55 
-cavity, 52 
Marshall, veins of, 455 
Masseter muscle, 342 
falciform, 513 
frontal, 511, 513 
of kidney,77B 
ideal, 778 
limbic, 513 
of liver, caudate, 743 
left, 742 
quadrate, 742 
right, 742 
Spigelian, 743 
of mesial and tentorial sur- 
internal, 342 
Masseteric artery, 401 
fascia, 350 
faces, 512 
occipital, 511, 513 
parietal, 511, 513 
slender, 544 
temporal, 511, 513 
Lobule of ear, 678 
nerve, 581 
veins, 459 
Mastication, muscles of, 342 
Mastoid antrum, 675 
cells, 675 
lymph-nodes, 490 
Matrix of nail, 656 
Maxilla, 181 
Maxillary antrum, 666 
artery, internal, 399 
median, 497 
mastoid, 490 
maxillary, internal, 492 
median lumbar, 497 
mediastinal, anterior, 495 
posterior, 495 
superior, 495 
mesenteric, 497 
of liver, 738 
Loculi, 804 
Locus ceruleus, 540, 551 
lachrymalis, 692 
niger, 539 
Long buccal nerve, 582 
mesocolic, 497 INDEX. 
907 
Maxillary division of fifth 
nerve, 577 
inferior, 580 
Mesencephalon, 538 
aqueduct of, 539 
lateral groove of, 539 
nates of, 539 
testes of, 539 
Mesenchyme, 91 
Mesenteric artery, inferior, 430 
superior, 429 
lymph-nodes, 497 
plexus, inferior, 647 
superior, 647 
veins, inferior, 479 
superior, 479 
Mesenteries, 748 
Muscle or muscles, abductor lial- 
lucis, 321 
longus pollicis, 282 
minimi digiti, 279 
pedis, 321 
pollicis, 284 
accessorius ad ilio-costalera, 
329 
lymph-nodes, internal, 492 
process, 86 
veins, anterior internal, 459 
internal, 460 
Meatus, external auditory, 677 
inferior, 664 
accelerator u rinse, 821 
adductor brevis, 297 
gracilis, 297 
longus, 294 
magnus, 294 
obliquus hallucis, 322 
pollicis, 284 
transversus hallucis, 322 
affecting the orifice of the 
mouth, 344 
anconeus, 266 
articularis genu, 308 
of back, 325 
middle, 664 
superior, 665 
urinarius externus, 814 
female, 839 
internus, 786 
Meckel, cartilage of, 92 
Median nerve, 608 
veins, basilic, 469 
cephalic, 469 
Mediastinal artery, 409 
posterior, 425 
lymph-nodes, anterior, 495 
posterior, 495 
superior, 495 
Mediastinum testis, 804 
development of, 88 
Mesentery, 718 
Mesial surface, 512 
Mesocolic lymph-nodes, 497 
Mesoderm, 81 
organs derived from, 91 
Mesodermal somites, 82 
Mesonephros, 99 
Mesorchium, 802 
Mesothelium, 91 
Metacarpal bones, 144 
Metanephros, 99 
Metapore, 547 
Metasternum, 126 
Metatarsal artery, 453 
Metatarsus, bones of, 161 
Metatela, 546 
Metencephalon, development of, 
104 
biceps flexor cruris, 301 
cubiti, 263 
biventer cervicis, 330 
brachialis, 264 
brachio-radialis, 265 
buccinator, 346 
bulbo-cavernosus, 821, 842 
cervicalis ascendens, 329 
ciliary, 684 
classification of, 250 
Medical anatomy, 18 
Medulla oblongata, 545 
Medullary lamina, external, 525 
internal, 525 
velum, posterior, 546 
Meibomian glands, 692 
Merabrana granulosa, 824 
suprachoroidea, 684 
tympani, 675 
Membrane or membranes, 65 
basement, 41 
basilar, 670 
coccygeus, 821 
-column, 61 
complexus, 329 
compressor naris, 347 
nariurn minor, 347 
urethrae, 822 
vaginae, 842 
constrictor urethrae, 822, 842 
coraco-brachialis, 260 
-corpuscles, 61 
corrugator supercilii, 347 
cucullaris, 253 
deep transverse, 822 
deltoideus, 258 
depressor alae nasi, 347 
anguli oris, 346 
labii inferioris, 346 
diaphragma, 334 
digastricus, 338 
dilatator naris anterior, 347 
posterior, 347 
of dorsum of neck, 325 
Methods of study, 33 
Microscopic anatomy, 18 
Mid-brain, 538 
Middle cervical ganglion, 644 
commissure, 533 
cutaneous nerve of anterior 
of the brain, 558 
of cerebro-spinal axis, 557 
costo-coracoid, 354 
cutaneous, 74 
of Desceraei, 682 
fibro-serous, 67 
crural, 624 
ear, 674 
horn of lateral ventricle, 528 
spermatic fascia, 811 
superior dental nerve, 578 
Migration of testicle, 802 
Milk-teeth, 703 
Minute anatomy, 18 
of the lungs, 759 
Mitral valves, 369 
Moderator band, 369 
Modiolus, 673 
Molar glands, 699 
teeth, 703 
Monro, foramen of, 531 
sulcus of, 533 
Mons Veneris, 838 
Monticulus, 542 
Morgagni, hydatid of, 806, 835 
development of, 100 
Morphological anatomy, 20 
Morphology of skull, 199 
of vertebrae, serial, 125 
Morula, 79 
Motion, organs of, 32 
Mouth, 698 
Movement, kinds of, in joints, 205 
amoeboid, 38 
Mucus,' 73 
Mucous membranes, 71 
gastro-pulmonary, 71 
genito-urinary, 72 
Mullerian duct, 99 
hyaloid, 689 
interosseous, 238 
of Krause, 60 
lining cavity of cerebro-spinal 
axis, 69 
cavities in sustentacular tis- 
sues, 69 
vascular system, 68 
mucous, 71 
gastro-pulmonary, 71 
genito-urinary, 72 
pituitary, 666 
of Reissner, 670 
Schneiderian, 666 
ejaculator seminis, 821 
urinae, 821 
erector spinae, 327 
of expression, 343 
extensor brevis digitorum, 319 
pollicis, 282 
carpi radialis brevis, 270 
longus, 269 
ulnaris, 270 
communis digitorum, 277 
indicis, 278 
longus digitorum, 319 
hallucis, 319 
pollicis, 282 
minimi digiti, 278 
ossis metacarpi pollicis, 282 
primi internodii pollicis, 
282 
serous, 66 
proper, 68 
of spinal cord, 561 
synovial, 69 
articular, 70 
bursal, 70 
vaginal, 70 
tectorial, 672 
typical, 66 
vitelline, 825 
Membranous labyrinth, 668 
Meningeal artery, 398 
anterior, 402 
middle, 400 
posterior, 407 
small, 400 
nerve of ninth, 591 
of tenth, 597 
Meningo-rachidian veins, 472 
Multifidus muscle, 330 
Muscle or muscles, of the ab- 
domen, 331 
proprius hallucis, 319 
secundi internodii pollicis, 
282 
penis, 821 908 
INDEX. 
Muscle or muscles, of eyeball, 690 
of female perineum, 820, 842 
in fifth group of back, 329 
flexor accessorius, 317 
brevis digitorum, 317 
hallucis, 317 
minimi digiti, 275 
pedis, 317 
pollicis, 282 
carpi radialis, 269 
ulnaris, 269 
longus digitorum, 317 
hallucis, 316 
Muscle or muscles, moving 
fingers, 272 
outer part of forearm, 266 
the leg. 301 
shoulder, 253 
thigh, 289 
thumb, 280 
whole foot, 308 
forearm, 263 
hand, 269 
multifidus, 330 
mylo-hyoideus, 338 
of neck, 336 
Muscle or muscles, serratus raag- 
nus, 256 
posterior inferior, 326 
superior, 325 
of soft palate, 701 
soleus, 313 
sphincter ani externus, 821 
vaginae, 842 
spinalis dorsi, 329 
splenius capitis, 326 
cervicis, 327 
colli, 327 
sterno-cleido-mastoideus, 337 
-hyoideus, 337 
-thyroideus, 337 
stylo-hyoideus, 338 
subclavius, 257 
subcostales, 336 
suboccipital, 330 
subscapularis, 263 
superficial, of head, 342 
supinator, 268 
supraspinatus, 260 
suspensory, 723 
temporalis, 342 
tensor fasciae latse, 292 
vaginae fernoris, 292 
teres major, 261 
minor, 261 
in third layer of back, 325 
of thorax, 334 
thyro-hyoideus, 338 
tibialis anterior, 308 
posterior, 308 
trachelo-mastoideus, 329 
transversalis abdominis, 333 
cervicis, 329 
transversus pedis, 322 
perinei, 821, 842 
thoracis anterior, 336 
trapezius, 253 
triangularis sterni, 336 
triceps extensor cubiti, 265 
surae, 314 
of trunk, 325 
of tympanum, 677 
of upper limb, 251 
vastus externus, 307 
intermedius, 307 
internus, 307 
lateralis, 307 
medialis, 307 
pollicis, 282 
ossis metacarpi minimi dig- 
iti, 275 
nomenclature of, 248 
of nose, 347 
obliquus capitis inferior, 331 
superior, 331 
externus abdominis, 332 
internus abdominis, 332 
obturator externus. 298 
pollicis, 281 
perforans, 274 
perforatus, 273 
digitorum pedis, 317 
profundus digitorum, 274 
sublimis digitorum, 273 
of forehead, 347 
in fourth layer of back, 327 
of front and side of neck, 337 
frontalis, 348 
gastrocnemius, 309 
gemellus inferior, 301 
superior, 298 
general considerations, 245 
genio-hyoideus, 339 
gluteus maxirnus, 291 
medius, 292 
minimus, 292 
gracilis, 297 
of head, 341 
iliacus, 291 
ilio-costalis, 327 
internus, 299 
occipitalis, 348 
occipito-frontalis, 348 
omo-hyoideus, 337 
opponens minimi digiti, 275 
pollicis, 281 
orbicularis oris, 345 
palmaris brevis, 285 
longus, 269 
papillary, 368 
pectineus, 297 
pectoralis major, 260 
minor, 256 
peroneus brevis, 316 
longus, 316 
tertius, 308 
of pharynx, 711 
of pinna, 678 
plantaris, 314 
platysrna, 337 
popliteus, 302 
pronator quadratus, 267 
teres, 267 
psoas magnus, 290 
parvus, 323 
pterygoideus externus, 342 
internus, 342 
pyrarnidalis, 332 
nasi, 347 
pyriformis, 298 
quadratus fernoris, 298 
lumborum, 334 
ilio-psoas, 291 
infracostales, 336 
infraspinatus, 261 
intercostales extern!, 336 
interni, 336 
interossei dorsales manus, 278 
pedis, 322 
palmares, 280 
plantares, 323 
volares, 280 
interspinales, 330 
intertransversales, 330 
ischio-cavernosus, 821, 842 
of larynx, 771 
latissimus, 261 
levator anguli oris, 346 
ani, 821, 842 
labii alaeque nasi, 346 
inferioris, 346 
superioris proprius, 346 
proprius ahe nasi anterior, 
347 
plantae, 317 
quadriceps extensor cruris, 303 
rectus abdominis, 331 
capitis anterior major, 340 
minor, 340 
lateralis, 340 
posterior major, 330 
minor, 331 
fernoris, 304 
rhomboideus major, 255 
minor, 255 
risorius, 346 
rotatores, 330 
sacro-lumbalis, 329 
sartorius, 301 
scalenus anterior, 339 
medius, 339 
posterior, 340 
semimembranosus, 301 
semispinalis capitis, 329 
cervicis, 330 
dorsi, 330 
semitendinosus, 301 
vesico-pubic, 361, 787 
zygomaticus major, 346 
minor, 346 
Muscular system, development 
of, 98 _ 
tissue, cardiac, 61 
cross-striped, 57 
plain, 58 
Musculi pectinati, 368 
Musculo-cutaneous nerve, 608 
of leg, 637 
-phrenic artery, 409 
-spiral nerve, 614 
Myelon, 499 
Mylo-hyoideus muscle, 308 
Myocardium, the, 367 
posterior, 347 
scapulae, 254 
levatores costarurn, 336 
longissirnus dorsi, 329 
longus colli, 341 
of lower limb, 287 
classification of, 288 
lumbricales manus, 276 
pedis, 318 
masseter, 342 
internal, 342 
of mastication, 342 
N. 
Naboth, ovula of, 833 
Nails, 656 
matrix of, 656 
Nares, anterior, 663 
posterior, 663 
moving arm, 258 
digits of foot, 316 
fifth metacarpal bone, 272 INDEX. 
909 
Nasal artery, 402 
lateral, 397 
Nerve or nerves, cutaneous, small 
internal, 612 
deep temporal, 581 
dental, anterior superior, 578 
inferior, 582 
middle superior, 578 
posterior superior, 578 
descendens hypoglossi, 597 
digital, of foot, 635 
dorsal, of penis, 631 
efferent, 65 
eighth, 589 
eleventh, 596 
nuclei of, 590 
external anterior thoracic, 608 
cutaneous, 624 
of musculo-spiral, 615 
laryngeal, 594 
palatine, 580 
plantar, 635 
popliteal, 636 
pterygoid, 582 
respiratory, 607 
superficial petrosal, 587 
facial, 585 
fibular, 634 
Nerve or nerves, interosseous, 
posterior, 616 
of Jacobson, 591 
jugular, 643 
labial, superior, 579 
lachrymal, 576 
laryngeal, internal, 594 
superior, 594 
lateral nasal, 579 
least splanchnic, 646 
lingual, 583 
of ninth, 591 
of seventh, 587 
of vagus, 597 
long buccal, 582 
saphenous, 625 
lumbar, 622 
malar, of seventh, 588 
masseteric, 581 
median, 608 
external terminal division, 
611 
bone, 185 
cartilages, 664 
cavity, 663 
duct, 666, 694 
fossae, 664 
cavities opening into, 666 
nerve, 576 
lateral, 579 
superior, 580 
veins, transverse, 459 
Nasopalatine nerve, 580 
Naso-pharynx, 710 
Nates of mesencephalon, 539 
Navicular bone, 160 
fossa, 840 
Neck, back of, dissection of, 891 
deep dissection of, 892 
dorsum of, muscles of, 325 
and head, dissection of, 890 
lymph-nodes of, 489 
muscles of, 336 
side of, dissection of, 891 
sympathetic nerves in, 642 
triangles of, 411 
veins of, 457 
Nerve or nerves, 563 
meningeal, of ninth, 591 
of tenth, 597 
middle cutaneous, of anterior 
crural, 624 
superior dental, 578 
musculo-cutaneous, 608 
of leg, 637 
-spiral, 614 
nasal, 576 
lateral, 579 
internal terminal division, 
612 
fifth, 574 
mandibular division of, 580 
maxillary division of, 577 
inferior, 580 
sacral, 639 
sporadic ganglia of, 576 
first, 567 
cervical dorsal, primary di- 
vision of, 602 
fourth, 574 
sacral, 638 
frontal, 576 
ganglia of, 65 
genito-crural, 624 
glosso-pharyngeal, 591 
gluteal, inferior, 629 
superior, 629 
great auricular, 604 
deep petrosal, 580 
occipital, 602 
sciatic, 631 
splanchnic, 645 
superficial petrosal, 580, 
587 
hemorrhoidal, inferior, 631 
hypoglossal, 596 
iliohypogastric, 623 
ilioinguinal, 624 
inferior dental, 582 
gluteal, 629 
hemorrhoidal, 631 
laryngeal, 594 
palpebral, 579 
pudendal, 630 
inframandibular, 588 
infraorbital, 579 
of seventh, 588 
infratrochlear, 576 
intercostal, 619 
internal anterior thoracic, 608 
cutaneous, 612 
of anterior crural, 625 
of musculo-spiral, 615 
laryng eal, 594 
plantar, 634 
popliteal, 632 
pterygoid process, 581 
saphenous, 625 
interosseous, anterior, 610 
abdominal, 596 
abducent, 585 
accessory obturator, 626 
afferent, 65 
anterior crural, 624 
interosseous, 610 
palatine, 580 
superior dental, 578 
tibial, 637 
of Arnold, 594 
auditory, 589, 674 
distribution in labyrinth, 
672 
superior, 580 
nasopalatine, 580 
ninth, 591 
nuclei of, 590 
obturator, 626 
accessory, 626 
occipital, great, 602 
small, 604 
third, 603 
oculo motor, 571 
oesophageal, 596 
olfactory, 567 
optic, 568 
palatine, anterior, 580 
external, 580 
auricular, great, 604 
posterior, 587 
of tenth, 594 
auriculo-temporal, 582 
of Bell, 607 
buccal, 588 
long, 582 
calcaneo-plantar, 684 
cardiac, 643, 644 
cervical, 595 
thoracic, 595 
cerebro-spinal, 563 
typical, 563 
•cervical, 603 
cardiac, 595 
superficial, 605 
chorda tympani, 587 
ciliary, 686 
short, 577 
circumflex, 613 
coccygeal, 627, 639 
communican.s hypoglossi, 597 
cranial, 565 
deep origins, 566 
superficial origins, 565 
crural, anterior, 624 
cutaneous, external, 624 
of musculo-spiral, 615 
internal, 612 
of anterior crural, 625 
of musculo-spiral, 615 
middle of anterior crural, 
624 
posterior, 580 
palmar, cutaneous, of median, 
611 
palpebral, inferior, 579 
patellar, 626 
perforating cutaneous, 630 
perineal, 631 
peroneal, 636 
petrosal, external superficial, 
587 
of ulnar, 612 
great deep, 580 
superficial, 580,587 
small deep, 591 
superficial, 587 
pharyngeal, of ninth, 591 
of sympathetic, 643 
of tenth, 594 
of Vidian, 580 
phrenic, 605 
plantar, external, 635 
internal, 634 
pneumogastric, 592 
popliteal, external, 636 
internal, 632 
posterior auricular, 587 
perforating, 630 910 
INDEX. 
Nerve or nerves, posterior inter- 
osseous, 616 
palatine, 580 
superior dental, 578 
thoracic, 607 
tibial, 633 
pterygoid, external, 582 
pudendal, inferior, 630 
pudic, 631 
pulmonary, 595 
radial, 616 
recurrent laryngeal, 594 
respiratory, external, 607 
rhomboid, 606 
-roots, spinal, 557 
sacral, 627 
fifth, 639 
fourth, 638 
sciatic, great, 631 
small, 629 
second, 568 
Nerve or nerves, thoracic, pos- 
terior, 607 
twelfth, 621 
tibial, anterior, 637 
posterior, 633 
tonsillar, of ninth, 591 
trifacial, 574 
trochlear, 574 
twelfth, 596 
thoracic, 621 
tympanic, 591 
ulnar, 612 
vagus, 592 
Yidian, 579 
of Wrisberg, 612 
Nervi nervorum, 64 
vasorum, 375 
Nervous system, development of, 
103 
Oblongata, 545 
development of, 104 
foramen caecum of, 545 
lateral column of, 545 
tract of, 545 
olive of, 546 
sensory nucleus of, 548 
Obturator artery, 434 
external, 434 
internal, 434 
externus muscle, 298 
fascia, 360 
interims muscle, 299 
foramen, 149 
nerve, 626 
accessory, 626 
veins, 480 
Occipital artery, 397 
bone, 165 
gyri, 516 
tunic of eye, 686 
Neural arch, 115 
seventh, 585 
branches of, below base of 
skull, 587 
ligaments uniting, 207 
Neurilemma, 63 
Neuroblasts, 103 
Neuro-epithelium, 43 
Neuroglia, 50 
development of, 103 
Neuromeres, 104 
Neuron, 62 
Neuroplasm, 64 
Ninth nerve, 591 
nuclei of, 590 
lobe, 511, 513 
nerve, great, 602 
small, 604 
third, 603 
sinus, 465 
veins, 460, 463 
Occipitalis muscle, 348 
Occipito-frontalis muscle, 348 
Oculo-motor nerve, 571 
in petrous bone, 587 
cervicofacial division of, 588 
pars intermedia of, 585 
temporofacial division of, 
588 
short ciliary, 577 
sixth, 585 
of skin, 653 
Odontoblasts, 86 
(Esophageal artery, 410, 425 
nerves, 596 
(Esophagus, 712 
Olfactory bulb, 567 
fissure, 515 
nerve, 567 
organs, development of, 106 
tract, 567 
Olivary nuclei, accessory, 547 
Olive of oblongata, 546 
Omenta, 749 
Omentum, gastro-colic, 751 
great, 751 
Omo-hyoideus muscle, 337 
Oogenesis, 78 
Opening, auriculo-ventricular, 
left, 369 
right, 367 
saphenous, 362 
Operculum, 512 
Ophthalmic artery, 402 
division of fifth nerve, 575 
ganglion, 577 
veins, common, 467 
inferior, 467 
superior, 467 
Opponens minimi digiti, 275 
pollicis muscle, 281 
Optic chi asm a, 568 
commissure, 568 
nerve, 568 
tract, 568 
Ora serrata, 687 
small deep petrosal, 591 
internal cutaneous, 612 
occipital, 604 
sciatic, 629 
splanchnic, 646 
superficial petrosal, 587 
spheno-palatine, 578 
spinal, 598 
accessory, 596 
anterior, primary divisions 
of, 603 _ 
dorsal, primary divisions of, 
601 
Nodes of Kanvier, 63 
Nodule, cerebellar, 544 
Nomenclature of muscles, 248 
Normal anatomy, 20 
skiagraphs, 870 
Nose, 663 
infundibulum of, 666 
muscles of, 347 
Nostrils, 663 
Notch, interclavicular, 127 
sacro-sciatic, great, 147 
small, 148 
Notochord, 81, 91 
Nourishment, organs supplving, 
31 
mode of distribution of, 600 
splanchnic, great, 645 
least, 646 
small, 646 
subclavius, 607 
suboccipital, 602 
subscapular, 608 
superficial cervical, 605 
temporal, 582 
superior gluteal, 629 
labial, 579 
laryngeal, 594 
nasal, 580 
supramandibular, 588 
suprascapular, 607 
supratrochlear, 576 
sympathetic, 639 
in the neck, 642 
temporal, deep, 581 
of seventh, 588 
Nuck, canal of, 803 
Nuclei, accessory olivary, 547 
arciform, 547 
of cranial nerves, 569 
Nucleolus, 38 
Nucleus, 38 
ambiguus, 548 
amygdaloid, 526 
caudate, 524 
cuneatus, 547 
dentate, 547 
emboli form is, 544 
fastigii, 544 
globosus, 544 
gracilis, 547 
lenticular, 525 
of olive, 547 
red, 539 
sensory, of oblongata, 548 
Nymphse, 839 
Oral sinus, 86 
Orbicularis oris muscle, 345 
Orbits, 194 
dissection of, 892 
Organ or organs, auditory, de 
velopment of, 108 
of Corti, 671 
development of, 109 
derived from ectoderm, 103 
from endoderm, 86 
of digestion, 695 
enamel, 86 
superficial, 582 
temporo-rnalar, 578 
tenth, 592 
nuclei of, 590 
third, 571 
occipital, 603 
thoracic, 619 
cardiac, 595 
external anterior, 608 
internal anterior, 608 
O. 
Obex, 547 
Obliquns capitis, inferior, 331 
superior, 331 
externns abdominis, 332 
internus abdominis, 332 INDEX. 
911 
Organ or organs, framework, 32 
generative, 801 
female, 822 
Palmar cutaneous nerve of ul- 
nar, 612 
fascia, 356 
Palmaris brevis muscle, 285 
longus muscle, 269 
Palpebrse, 691 
Palpebral artery, 402 
ligaments, 693 
nerve, inferior, 579 
veins, inferior, 459 
Pampiniform plexus, 475, 806, 
812 
Perforating artery, posterior, 449 
of radial, 423 
cutaneous nerve, 630 
Pericardial artery, 425 
Pericardium, 366, 373 
Perimysium, 61 
Perineal artery, superficial, 436 
transverse, 436 
nerves, 631 
Perineum, development of, 102 
fascia of, 361 
female, dissection of, 889 
male, dissection of, 888 
Perineurium, 64 
central point of, 820 
muscles of female, 842 
Periosteum, 52 
Peritoneal ligaments, 750 
Peritoneum, 748 
male, 801 
of Giraldes, 807, 835 
development of, 101 
gustatory, development of, 106 
of internal secretion, 32 
of Jacobson, 666, 667 
of motion, 32 
olfactory, development of, 106 
of relation, 32 
removing waste matters, 30 
of reproduction, 33 
of respiration, 755 
physiological anatomy, 755 
of Eosenmuller, 835 
of special senses, 651 
Pancreas, 736 
development of, 91 
Pancreatic artery, 429 
duct, 737 
Pancreatico - duodenalis artery, 
inferior, 430 
superior, 428 
Papilla, hair, 658 
lachrymalis, 692 
Papillae, circumvallate, 660 
filiform, 661 
fungiform, 661 
Papillary muscles, 368 
Paracentral gyrus, 515 
Paradidymis, 807 
Parathyroids, 799 
Parietal bones, 168 
gyri, 515 
lobe, 511, 513 
Parieto-occipital fissure, 511 
Paroophoron, development of, 
100 
supplying nourishment, 31 
systems of, 29 
tactile, development of, 106 
of taste, 662 
Orifice, pyloric, 717 
Oro pharynx, 710 
Os calcis, 159 
external, 830, 831 
internal, 829, 831 
innominatum, 146 
Magnum, 143 
pubis, 149 
Osseous labyrinth, 672 
tissue, 52 
cancellous, 53 
spongy, 53 
Ossicles of ear, 676 
Ossicula auditus, 676 
Ossification of sternum, 127 
of vertebrae, 124 
Ostium abdominale, 828 
Periurethral glands, 841 
Peroneal artery, 447 
nerve, 636 
Peroneus brevis muscle, 316 
longus muscle, 316 
tertius muscle, 308 
Pes anserinus, 588 
hippocampi, 529 
Petit, canal of, 689 
Petrosal nerve, external super- 
ficial, 587 
great deep, 580 
superficial, 587 
small deep, 591 
superficial, 580, 587 
sinus, inferior, 466 
superior, 466 
Petro-squarnous sinus, 466 
Petrous ganglion, 591 
Peyer, patches of, 724 
Phalanges of foot, 162 
of hand, 144 
ungual, 146 
Pharyngeal artery, 398 
ascending, 398 
bursa, 710 
nerve of ninth, 591 
Parotid fascia, 350 
gland, 735 
lymph-nodes, 492 
veins, 459, 460 
Parovarium, 835 
development of, 100 
Pars ciliaris retinae, 687 
intermedia of seventh nerve, 
585 
internum, 827 
Otic ganglion, 584 
Otoliths, 669 
Ovarian artery, 431 
fimbria, 824 
plexus, 646 
veins, 475 
Ovaries, 822 
development of, 99 
Oviducts, 827 
Ovula of Naboth, 833 
iridica retime, 687 
Patches of Peyer, 724 
Patella, 154 
Patellar nerve, 626 
Pathological anatomy, 20 
Paths, conduction, in spinal 
cord, 554 
Pectineus muscle, 297 
Pectoral fascia, 353 
lymph-nodes, 493 
Pectoralis major, 260 
minor, 256 
Peduncles of callosum, 520 
cerebellar, 542, 544 
cerebral, 538 
Pelvic cavity of female, dissec- 
tion of, 888 
of male, dissection of, 888 
fascia, 360 
plexus, 648 
Pelvis, 150 
articulations of, 227 
of ureter, 784 
veins of, 479 
Penis, 812 
yr development of, 102 
dorsal artery of, 436 
nerve of, 631 
veins of, 480 
of sympathetic, 644 
of tenth, 594 
plexus, 461 
tonsil, 710 
Pharyngoglossus, 711 
Pharynx, 710 
muscles of, 711 
Philosophic anatomy, 20 
Phrenic artery, 431 
superior, 409 
nerve, 605 
Pacchioni, glandules of, 561 
Pacinian corpuscles, 655 
Palate bone, 183 
hard, 699 
pillars of, 700 
soft, 700 
Palatine artery, ascending, 397 
descending, 401 
glands, 700 
nerve, anterior, 580 
external, 580 
posterior, 580 
Palatoglossus, 701 
Palatopharyngeus, 701 
Palatum durum, 699 
P. 
plexus, 646 
Phreno-colic ligament, 750 
-splenic ligament, 794 
Physiological anatomy, 20 
Pia mater, 500 
of brain, 560 
of spinal cord, 561 
Pigmented epithelium, 43 
Pillars of palate, 700 
Pineal gland, 535 
Pinna, 678 
molle, 700 
Palm, dissection of, 886 
Palmar arch, deep, 422 
superficial, 420 
artery of ulnar, deep, 420 
cutaneous nerve of median, 
611 
muscles of, 678 
Pisiform bone, 143 
Pituitary gland, 534 
membrane, 666 
Placenta, development of, 83, 85 
Plain muscular tissue, 58 
Plantar artery, external, 449 
suspensory ligament of, 816 
Perforated space, anterior, 525 
Perforating artery, 409 912 
INDEX. 
Plantar artery, internal, 449 
fascia, 364 
Post-pharyngeal lymph-nodes, 
492 
Pyramidalis muscle, 332 
nasi muscle, 347 
Pyriformis fascia, 361 
muscle, 298 
nerve, external, 635 
Plantaris muscle, 314 
Platysma muscle, 337 
Pleurae, 765 
Plexus or plexuses, aortic, 647 
basilar, 466 
brachial, 606 
cardiac, 648 
carotid, 643 
cavernous, 643 
cervical, 603 
choroid, 526 
of fourth ventricle, 546 
coeliac, 646 
Pouch of Broca, 839 
laryngeal, 773 
recto-vesical, 787, 831 
utero-vesical, 831 
Poupart’s ligament, 332 
Precentral fissure, 514 
gyrus, 515 
Precuneal fissure, 513 
Precuneus, 516 
Prepuce, 815 
Prevertebral artery, 398 
fascia, 352 
Prickle cells, 43 
Primitive streak, 81 
Primordial ova, 825 
Princeps pollicis artery, 422 
Process, ensiform, 126 
falciform, 362 
fronto-nasal, 86 
mandibular, 86 
maxillary, 86 
xiphoid, 126 
Processes, ciliary, 685 
Processus reticularis, 553 
vaginalis, 802, 812 
Profunda artery, inferior, 416 
superior, 416 
Pronator quadratus, 267 
teres, 267 
Pronephros, 98 
Prosencephalon, development of, 
105 
Q. 
Quadrate lobe of liver, 742 
Quadratus femoris muscle, 298 
lumborum muscle, 334 
plantse muscle, 317 
Quadriceps extensor cruris, 803 
Quadrigemina, development of, 
105 
coronary, 649 
diaphragmatic, 646 
epigastric, 649 
hemorrhoidal, 480, 648 
hypogastric, 647 
inferior mesenteric, 647 
lumbar, 622 
mesenteric, inferior, 647 
superior, 647 
ovarian, 480, 646 
pampiniform, 475, 806, 812 
patellae, 626 
pelvic, 648 
pharyngeal, 461 
phrenic, 646 
prostatic, 480, 648 
pterygoid, 460 
renal, 646 
Radial artery, 421 
nerve, 616 
K. 
recurrent artery, 421 
veins, 469 
Eadialis indicis artery, 422 
Radius, 139 
Ramus cervicalis descendens, 
605 
communicans peronei, 636 
descendens hypoglossi, 597 
Ranine artery, 396 
veins, 461 
Ranvier, nodes of, 63 
Receptaculum chyli, 487 
seminis, 827 
Recess, spheno-ethmoidal, 665 
Rectal ampulla, 733 
lymph-nodes, 497 
Recto-vaginal ligament, 832 
-vesical fascia, 361 
pouch, 787, 831 
Rectum, 732 
semilunar valves of, 734 
Rectus abdominis muscle, 331 
capitis anterior major, 340 
minor, 340 
lateralis, 340 
posterior major, 330 
minor, 331 
sacral, 628 
solar, 649 
spermatic, 646 
subsartorial, 627 
superior mesenteric, 647 
suprarenal, 646 
uterine, 480, 648, 835 
vaginal, 480, 648 
vesical, 480, 648 
Plica semilunaris, 694 
sigmoidea, 726 
recti, 733 
Pneumogastric nerve, 592 
Poraum Adami, 767 
Pons, development of, 104 
Yarolii, 540 
Popliteal artery, 443 
lymph-nodes, 494 
nerve, external, 636 
internal, 632 
space, 444 
veins, 482 
Popliteus muscle, 302 
Porta, 535 
Prostate gland, 818 
Prostatic plexus, 480, 648 
Protoplasm, 38 
Psoas magnus muscle, 290 
parvus muscle, 323 
Pterygo-maxillary fissure, 191 
-palatine artery, 401 
Pterygoid artery, 401 
nerve, external, 582 
plexus, 460 
Pterygoideus externus, 342 
interims, 342 
Pubic artery, 439 
Pudendal nerve, inferior, 630 
Pudendum, 887 
Pudic arterv, deep external, 
443 
femoris muscle, 304 
Recurrent carpal artery, 423 
laryngeal nerve, 594 
Red nucleusj 539 
Region of aqueduct, 538 
subthalamic, 536 
internal, 435 
superficial external, 443 
nerve, 631 
veins, external, 481 
internal, 480 
Pulmonary arterial system, 379 
nerves, 595 
valve, 368 
of third ventricle, 531 
Regional anatomy, 18 
Regions of abdomen, 714 
Reil, island of, 511 
Reissner, membrane of, 670 
Relation of lobes to parts of lat- 
eral ventricle, 517 
organs of, 32 
Relational anatomy, 18 
Renal artery, 431 
plexus, 646 
Reproduction, cell, 39 
organs of, 33 
Reproductive organs, develop- 
ment of, 98 
Respiratory nerve, external, 607 
Restiform body, 546 
Restis, 546 
Rete testis, 804 
Portal fissure, 742 
system of veins, 477, 739 
Porus opticus, 687 
Postcentral gyrus, 516 
Posterior auricular nerve, 587 
brachium, 533 
commissure, 535 
forceps, 519 
horns of lateral veritricle, 528 
veins, 454 
Pulvinar, 533 
Punctum lachrymale, 692 
Pupil, 685 
Putamen, 525 
Pyloric artery, 428 
orifice, 717 
veins, 479 
Pylorus, 717 
Pyramid, cerebellar, 544 
decussation of, 545 
dorsal, 546 
of Ferreln, 780 
interosseous nerve, 616 
medullary velum, 546 
nares, 663 
palatine nerve, 580 
perforated space, 534 
superior dental nerve, 578 
thoracic nerve, 607 
Reticula, 554 
Reticular cartilage, 52 
lamina, 672 
of tympanum, 675 
ventral, 545 
Pyramidal bone of carpus, 141 
tibia! nerve, 633 
Retina, 686 INDEX. 
913 
Retrahens aurem, 679 
Bhinencephalon, development 
of, 106 
Rhomboid nerve, 606 
Rhomboidens major, 255 
minor, 255 
Ribs, 127 
Sciatic artery, 436 
nerve, great, 631 
small, 629 
Scleral sulcus, 682 
Sclerotic, 682 
Scrotal ligament, 801 
Scrotum, 809 
Sebaceous glands, 658 
Second nerve, 568 
Sella, diaphragm of, 559 
Semicircular canals, 669 
Semilunar, the, of the carpus, 
141 
Sinus or sinuses, superior petro- 
sal, 466 
transverse, 466 
urogenital, 102 
uterine, 835 
of Valsalva, 368 
venous, 455 
of cranium, 463 
Sixth nerve, 585 
Skeleton, development of, 91 
Skin, 651 
nerves of, 654 
asternal, 127 
development of, 92 
false, 127 
peculiar, 128 
sternal, 127 
true, 127 
typical, 128 
Right lobe of liver, 742 
Rima glottidis, 775 
pudendi, 839 
Ring, external abdominal, 332 
femoral, 360 
internal abdominal, 360 
Risorius muscle, 346 
valves of rectum, 734 
Semimembranosus muscle, 301 
Seminal vesicles, 808 
Semispinalis capitis muscle, 329 
cervicis muscle, 330 
dorsi muscle, 330 
Semitendinosus muscle, 301 
Sensory epithelium, 43 
Septa, intermuscular, of arm, ex- 
ternal, 355 
internal, 355 
of leg, 363 
of thigh, 362 
Septum auricularurn, 367 
lucidum, 522 
pectiniforme, 813 
posterius, 562 
transversum, 669 
Serratus magnus, 256 
posterior, inferior, 326 
superior, 325 
Sets of teeth, 703 
true, 653 
Skull, 164 
base of, 197 
development of, 92 
exterior of, 190 
externally, 192 
facial region of, 194 
morphology of, 199 
sutures of, 190 
temporal region of, 191 
various forms of, 200 
as a whole, 190 
Slender lobe, 544 
Small deep petrosal nerve, 591 
internal cutaneous nerve, 612 
intestine, 717 
tunics of, 718 
occipital nerve, 604 
sciatic nerve, 629 
splanchnic nerve, 646 
superficial petrosal nerve, 587 
Smegma preputii, 815 
Soft palate, 700 
muscles of, 701 
Solar plexus, 649 
Soleus muscle, 313 
Solitary fasciculus, 548 
glands, 720 
lymph-nodules, 720 
Somites, mesodermal, 82 
Space, axillary, 415 
epidural, 561 
of Fontana, 683 
interlabial, 839 
interpeduncular, 534 
perforated, anterior, 525 
posterior, 534 
popliteal, 444 
sublingual, 708 
Special senses, organs of, 651 
Spermatic artery, 431 
cord, 812 
plexus, 646 
veins, 475 
Spermatids, 77 
Spermatocytes, 77 
Spermatogenesis, 77 
Spermatogones, 77 
Spermatozoa, 77 
Sphenoid bone, 176 
Sphenoidal antrum, 666 
Spheno-ethmoidal recess, 665 
-maxillary fissure, 192 
fossa, 191, 192 
-palatine artery, 401 
nerve, 578 
Rods of Corti, 671 
Rolandic fissure, 510 
Root of lung, 763 
Rosenmiiller, organ of, 835 
Rostrum of callosum, 518 
Rotatores muscles, 330 
Round ligament, development 
of, 100 
of liver, 745 
ligaments of uterus, 832 
S. 
Sac, lachrymal, 692 
Saccule, 669 
Sacculus laryngis, 773 
Saccus endolyraphaticus, 669 
Sacral artery, lateral, 437 
lymph-nodes, 497 
nerves, 627 
fifth, 639 
fourth, 638 
plexus, 628 
veins, lateral, 480 
middle, 476 
Sacro-sciatic notch, great, 147 
small, 148 
-lumbalis muscle, 329 
Sacrum, 120 
Salivary glands, 734 
Sand, brain, 535 
Saphenous opening, 362 
veins, external, 481 
internal, 481 
long, 481 
short, 481 
Sarcolernma, 61 
Sarcoplasm, 60 
Sartorius muscle, 301 
Scala media, 670 
tympani, 674 
vestibuli, 674 
Scalenus muscle, anterior, 339 
medius, 339 
posterior, 340 
Scaphoid bone of the carpus, 
141 
Seventli nerve, 585 
Sharpey, fibres of, 54 
Sheaths, crural, 359 
fascial, of tendons of hand, 357 
femoral, 359 
Shelf, dental, 86 
Shield, embryonic, 80 
Shoulder, fascia of, 354 
-joint, 218 
muscles moving, 253 
Sigmoid artery, 431 
colon, 730 
sinus, 465 
Simple epithelium, 44 
Sinus or sinuses, basilar, 466 
cavernous, 466 
circular, 466 
coronary, 455, 466 
frontal, 666 
inferior longitudinal, 464 
petrosal, 466 
intercavernous, 466 
jugular, 461 
of kidney, 781, 782 
lateral, 464 
longitudinal, superior, 463 
inferior, 464 
occipital, 465 
oral, 86 
petrosal, inferior, 466 
superior, 466 
petro-squamous, 466 
pocularis, 790 
development of, 101 
of portal vein, 477 
prsecervicalis, 87 
sigmoid, 465 
spheno-parietal, 466 
straight, 464 
superior longitudinal, 463 
of tarsus, 160 
Scapula, 133 
ligaments of, 218 
Scapular artery, posterior, 411 
Scarpa, triangle of, 440 
Schlemm, canal of, 683 
Schneiderian membrane, 666 
-parietal sinus, 466 
Sphincter ani externus, 821 
internal, 734 
of urethra, 788 
iridis, 686 
vaginae, 842 
I Spigelian lobe, 743 914 
INDEX. 
Spinal accessory nerve, 596. 
artery, 425 
anterior, 407 
lateral, 407 
posterior, 407 
bulb, 545 
canal, 124 
cord, 499, 552 
arachnoid of, 561 
central canal of, develop- 
ment of, 103 
Stratified epithelium, 44 
Stratum corneura, 653 
dorsal e, 536 
granulosum, 653 
intermedium, 539 
lucidurn, 653 
Streak, primitive, 81 
Striae acusticse, 547 
longitudinales, 520 
Striatum, corpus, 523 
Structure of tongue, 708 
Study, methods of, 33 
Styloglossus, 709 
Stylo-hyoideus muscle, 338 
-mandibular ligament, 300, 352 
-mastoid artery, 398 
-pharyngeus, 711 
Subarachnoid space, 561 
Subcalcarine gyrus, 516 
Subclavian artery, 404 
lymph-nodes, 493 
veins, 470 
Subclavius muscle, 257 
nerve, 607 
Subcollateral gyrus, 516 
Subcostales muscles, 336 
Suprarenal plexus, 646 
Suprascapular artery, 410 
nerve, 607 
Supraspinatus muscle, 260 
Supraspinous fascia, 355 
Suprasternal artery, 410 
Supratrochlear nerve, 576 
Surcingle, 524 
Surface, mesial, of cerebrum, 512 
parts, delimitations of, 21 
names of, 21 
tentorial, of cerebrum, 512 
Surfaces of heart, 371 
of liver, 742 
columns of, 553 
conduction paths in, 554 
dura of, 561 
fissures of, 553 
gray matter of, 553 
membranes of, 561 
pia of, 561 
topographical anatomy of, 
600 
Surgical anatomy, 18 
Suspensory ligament of lens, 689 
of liver, 745 
of ovary, 824 
of penis, 816 
muscle, 723 
Sustentacular tissues, 45 
Sustentaculum tali, 159 
Sutures, 204 
tracts of, 554 
veins of, 473 
furrow, 124 
nerve-roots, 557 
nerves, 598 
veins, dorsal, 472 
longitudinal anterior, 472 
posterior, 473 
Spinalis dorsi muscle, 329 
Spine, 115 
veins of, 472 
as a whole, 123 
of skull, 190 
Sweat-glands, 659 
Sweetbread, 736 
Syllabus of the systemic arteries, 
381 
Subdural space, 560 
Sublingual artery, 396 
gland, 736 
space, 708 
Sublobular veins, 740 
Submandibular ganglion, 583 
Submaxillary ganglion, 583 
gland, 735 
lymph-nodes, 490 
Submental artery, 397 
Suboccipital lymph-nodes, 490 
muscle, 330 
nerve, 602 
Subsartorial plexus, 627 
Subscapular artery, 411, 415 
fascia, 355 
lymph-nodes, 493 
nerves, 608 
Subscapularis muscle, 263 
Substantia gelatinosa, 553 
Subthalamic region, 536 
Suburethral glands, 820 
Sulcus of Monro, 533 
scleral, 682 
spiralis, 672 
Superficial cervical nerves, 605 
fascia, 349 
lymph-vessels, 485 
temporal nerve, 582 
veins, 455 
Superior cervical ganglion, 642 
fovea, 551 
gluteal nerve, 629 
labial nerve, 579 
laryngeal nerve, 594 
mesenteric plexus, 647 
nasal nerves, 580 
parietal gyrus, 516 
vena cava, 456 
Supra-acromial artery, 411 
Suprahyoid lymph-nodes, 490 
Supramandibular nerve, 588 
Supramarginal gyrus, 516 
Supraorbital artery, 402 
fissure, 515 
veins, 459 
Suprarenal artery, 431 
bodies, development of, 98 
capsules, 798 
Sylvian fissure, 510 
veins, deep, 468 
Sympathetic nerves, 639 
system, development of, 106 
Symphysis pubis, 149, 229 
Synarthrosis, 204 
Synovia, 69 
Synovial membranes, 69 
articular’, 70 
bursal, 70 
vaginal, 70 
System, absorbent, 485 
blood-vascular, 365 
Haversian, 53 
lymphatic, 484 
urinary, 777 
vascular, 30 
Systems of organs, 29 
functions of, 29 
Systematic anatomy, 18 
Systemic veins, 455 
Spiral ganglion, 674 
ligament, 674 
Spitzka-Lissauer tract, 556 
Splanchnic nerve, great, 645 
least, 646 
small, 646 
Spleen, 793 
accessory, 795 
development of, 98 
pulp, 795 
Splenic artery, 428 
flexure, 729 
veins, 479 
Splenium, 518 
Splenius capitis muscle, 326 
cervicis muscle, 327 
colli muscle, 327 
Spongioblasts, 103 
Spongioplasm, 38 
Sporadic ganglia of fifth nerve, 
576 
T. 
Spot, germinal, 826 
yellow, 687 
Stapedius, 677 
Stapes, 676 
Stenson, duct of, 735 
Stenson’s canal, 666 
Sternal lymph-nodes, 495 
Sterno-cleido-mastoideus muscle, 
337 
Tactile organs, development of, 
106 
Taenia semicircularis, 524 
Tarsal artery, 452 
Tarsus, 692 
bones of, 158 
joints of, 240 
Taste-buds, 661 
organs of, 662 
Tectorial membrane, 672 
Teeth, 702 
bicuspid, 703 
canine, 703 
deciduous, 703 
-hyoideus muscle, 337 
-mastoid artery, 395, 399 
-thyroideus muscle, 337 
Sternum, 126 
development of, 127 
ossification of, 127 
development of, 86 
eruption of, 703 
incisor, 702 
milk, 703 
molar, 703 
sets of, 703 
temporary, 703 
Tegmentum, 539 
Temporal artery, 401 - 
Stilling, canal of, 689 
Stomach, 715 
coronary veins of, 479 
development of, 90 
tunics of, 716 
Stomodaeum, 86 
Straight sinus, 464 INDEX. 
915 
Temporal artery, anterior, 399 
middle, 399 
posterior, 399 
bones, 171 
fascia, 350 
fossa, 191 
gyri, 516 
lobe, 511, 513 
nerve, deep, 581 
superficial, 582 
region of skull, 191 
of seventh nerve, 588 
veins, anterior, 463 
common, 459 
middle, 459 
posterior, 463 
superficial, 459 
Temporalis muscle, 342 
Temporary teeth, 703 
Temporo-facial division of sev- 
enth nerve, 588 
-malar nerve, 578 
-maxillary veins, 459 
Tendons, general considerations, 
245 
Thorax as a whole, 130 
Thumb, muscles moving, 280 
Thymus, 797 
development of, 88 
Thyi’o-arytenoideus, 772 
-epiglottideus, 772 
-glossal duct, 796 
-hyoideus muscle, 338 
Thyroid artery, inferior, 410 
axis, 410 
b0dy,796 
cartilage, 768 
gland, 796 
accessory, 797 
development of, 88 
isthmus of, 796 
veins, inferior, 462 
middle, 462 
superior, 462 
Tibia, 155 
Tibial artery, anterior, 450 
posterior, 446 
recurrent artery, anterior, 451 
posterior, 451 
nerve, anterior, 637 
posterior, 633 
Tibialis muscle, anterior, 308 
posterior, 308 
Tissues, adenoid reticular, 50 
adipose, 49 
areolar, 47 
cardiac muscular, 61 
cartilaginous, 51 
classes of, 41 
connective, 46 
dentinal, 56 
elastic, 47 
elementary, 37 
epithelial, 41 
fatty, 49 
gelatinous, 50 
of the heart, 366 
liquid, 57 
muscular, 58 
plain, 58 
cross-striped, 59 
nervous, 62 
osseous, 52 
cancellous, 53 
Tract of spinal cord, 554 
Spitzka-Lissauer, 556 
uveal, 683 
Tragus, 678 
Transcendental anatomy, 20 
Transitional epithelium, 44 
Transversalis abdominis muscle, 
333 
cervicis muscle, 329 
colli artery, 411 
fascia, 359 
Transverse colon, 729 
fissure, 528,742 
sinus, 466 
Transversus thoracis muscle, an- 
terior, 336 
pedis muscle, 322 
perinei muscle, 821, 842 
Trapezium, 143 
cerebellar, 542 
Trapezius muscle, 253 
Trapezoid, 143 
Triangle interdeferential, 808 
Scarpa’s, 440 
Triangles of the neck, 411 
Triangularis sterni muscle, 336 
Triceps extensor cubiti, 265 
surae muscle, 314 
Tricuspid valve, 368 
Trifacial nerve, 574 
Trigonum of bladder, 785 
Trochlear nerve, 574 
Trolard, veins of, 468 
True cartilage, 51 
ribs, 127 
skin, 653 
vertebrae, 115 
vocal cords, 770 
Trunk, articulations of, 205 
muscles of, 325 
Tuba auditiva, 676 
Tube, Eustachian, 676 
Tuber annulare, 540 
cinereum, 534 
Tendo oculi, 693 
Tenia tecta, 520 
Tenon, capsule of, 680 
Tensor fasciae latse, 292 
palati, 701 
tympani, 677 
vaginae femoris, 292 
Tenth nerve, 592 
nuclei of, 590 
Tentorial surface, 512 
Tentorium, 559 
of hypophysis, 559 
Teres major, 261 
minor, 261 
Terminal cone of spinal cord, 
553 
Testes, 801 
development of, 100 
of mesencephalon, 539 
Testicles, 801 
migration of, 802 
Thalami optici, 532 
Thalamencephalon, 531 
development of, 105 
Thalamus, optic, development 
of, 105 _ 
Thebesius, veins of, 456 
Thigh, fascia of, 362 
muscles moving, 289 
Third nerve, 571 
occipital nerve, 603 
ventricle, region of, 531 
Thoracic aorta, 423 
artery, alar, 415 
long, 415 
superior, 414 
cardiac nerves, 595 
duct, 487 
fascia, 353 
portion of gangliated cord, 644 
nerve, 619 
external anterior, 608 
internal anterior, 608 
cochleae, 675 
dorsal, cerebellar, 544 
Tubercle, acoustic, 551 
of Lower, 368 
Tubes, bronchial, 758 
Fallopian, 827 
development of, 100 
uriniferous, 777 
Tubo-ovarian ligament, 824 
Tubuli recti, 805 
seminiferi, 804 
Tunica albuginea, 804, 813 
ovarii, 824 
vaginalis, 803 
development of, 101 
vasculosa, 804 
Tunic or tunics, of alimentary 
canal, 697 
of eye, fibrous, 683 
vascular, 683 
spongy, 53 
sustentacular, 45 
white fibrous, 46 
yellow fibrous, 47 
Tongue, 660, 707 
development of, 88 
structure of, 708 
Tonsils, 711 
pharyngeal, 710 
Tonsillar artery, 397 
nerve of ninth, 591 
Topics, order of, 33 
Topographical anatomy, 18 
of spinal cord, 600 
Torcular Herophili, 166, 464 
Touch-corpuscles, 654 
Trachea, 757 
development of, 88 
Tracheal artery, 410 
Trachelo-mastoideus muscle, 329 
Tract of Burdach, 556 
nervous, 686 
of liver, 744 
of small intestine, 718 
of stomach, 716 
Turbinate bone, inferior, 185 
Twelfth nerve, 597 
posterior, 607 
twelfth, 621 
wall, veins of, 470 
Thorax, 126 
articulations of, 211 
of Goll, 556 
of Gowers, 555 
lateral, of oblongata, 545 
thoracic nerve, 621 
Tympanic artery, 400 
bone, 175 
lymph-nodes of, 495 
muscles of, 334 
olfactory, 567 
optic, 568 
nerve, 591 
Tympanum, 674 916 
INDEX. 
Tympanum, muscles of, 677 
Typical cerebro-spinal nerve, 563 
Valvula, 540 
Valvulse conniventes, 720 
Varolius, bridge of, 540 
Yas aberrans, 808 
Vascular system, 30 
membrane lining, 68 
tunic of eye, 683 
Yas deferens, 807 
development of, 101 
Vasa efferentia, 805 
Vein or veins, dorsal, of penis, 
480 
U. 
spinal, 472 
emissary, 463, 467 
epigastric, superficial, 481 
external iliac, 477 
jugular, 460 
pudic, 481 
saphenous, 481 
extraspinal, 472 
facial, 457 
anterior, 457 
common, 458 
Ulna, 137 
Ulnar artery, 417 
recurrent, 418 
nerve, 612 
veins, anterior, 469 
posterior, 469 
Umbilical cord, 83 
fissure, 742 
vesicle, 83 
Unciform, 143 
Uncinate gyrus, 517 
Ungual phalanges, 146 
Urachus, 102 
Ureters, 784 
development of, 99, 102 
infundibula of, 784 
pelvis of, 784 
Urethra, 787 
development of, 102 
female, 788 
internal sphincter of, 788 
male, 789 
membranous, 789 
prostatic, 789 
spongy, 789 
triangular ligament of, 361 
Urethral glands, 841 
Urinary bladder, 785 
system, 777 
Urinife;ous tube, 777 
Urogenital sinus, 102 
Uterine artery, 434 
plexus, 480, 648, 835 
sinuses, 835 
Utero-ovarian ligaments, 823 
-sacral ligaments, 832 
-vesical pouch, 831 
Uterus, 829 
cervix of, 830 
development of, 100 
fundus of, 830 
vasorum, 375 
Vastus externus muscle, 307 
intermedius muscle, 307 
internus muscle, 307 
lateralis muscle, 307 
medialis muscle, 307 
Vein or veins, anastomotic, great, 
468 
posterior, 459 
transverse, 460 
femoral, 482 
frontal, 459, 463 
of Galen, 456, 468 
gastric, 479 
posterior, 468 
angular, 458 
anterior auricular, 460 
cardiac, 456 
facial, 459 
internal maxillary, 459 
temporal, 463 
auricular, anterior, 460 
posterior, 460 
axillary, 470 
azygos, great, 471 
left lower, 472 
lower, left, 472 
right, 471 
small, 472 
basilic, 469 
median, 469 
brachio-cephalic, 457 
of brain, 467 
bronchial, 472 
gluteal, 480 
great anastomotic, 468 
cardiac, 455 
of bead and neck, 457 
of heart, 455 
hepatic, 740 
iliac, common, left, 476 
right, 476 
external, 477 
internal, 479 
superficial circumflex, 481 
ilio-lumbar, 476 
inferior mesenteric, 479 
palpebral, 459 
striate, 468 
thyroid, 462 
innominate, 457 
intercostal, 472 
superior, 471 
interlobular, 740 
internal jugular, 461 
mammary, 470 
maxillary, 460 
anterior, 459 
pudic, 480 
saphenous, 481 
interventricular, posterior, 456 
intralobular, 740 
intraspinal, 472 
jugular, anterior, 460 
external, 460 
buccal, 459 
cardiac, 455 
anterior, 456 
great, 455 
middle, 456 
posterior, 456 
smallest, 456 
cephalic, 470 
median, 469 
cerebellar, inferior, 468 
superior, 468 
cerebral, anterior, 468 
deep, 468 
inferior, 468 
middle, 468 
superficial, 467 
superior, 467 
cervical, deep, 463 
transverse, 460 
choroid, 468 
circumflex iliac, superficial, 
481 
masculinus, 790 
development of, 101 
Utricle, 668 
Uveal tract, 683 
Uvula, 700 
posterior, 460 
internal, 461 
posterior external, 460 
lateral sacral, 480 
left marginal, 456 
long saphenous, 481 
of lower limb, deep, 482 
superficial, 481 
of Lubbe, 468 
cerebellar, 544 
vesicae, 785 
V. 
Vagina, 835 
development of, 103 
Vaginal arteries, 434 
plexus, 480, 648 
synovial membrane, 70 
Vagus area, 551 
nerve, 592 
lumbar, 475 
common facial, 459 
iliac, 476 
temporal, 459 
coronary, 455 
right, 456 
small, 456 
of stomach, 479 
deep, 455 
cervical, 463 
ascending, 476 
mammary, internal, 470 
marginal, left, 456 
right, 456 
of Marshall, 455 
Vallecula, 542 
Valsalva, sinus of, 368 
Valve, aortic, 369 
bicuspid, 369 
Eustachian, 368 
ileo-csecal, 727 
-colic, 727 
mitral, 369 
pulmonary, 368 
semilunar, of rectum, 734 
tricuspid, 368 
of Vieussens, 540 
masseteric, 459 
maxillarv, anterior internal, 
459 ' 
internal, 460 
median, 469 
facial, 459 
Sylvian, 468 
development of, 96 
digital of foot, dorsal, 481 
of diploe, 463 
dorsal digital of foot, 481 
basilic, 469 
cephalic, 469 
meningo-rachidian, 472 
mesenteric, inferior, 479 
superior, 479 INDEX. 
917 
Vein or veins, middle sacral, 476 
temporal, 459 
thyroid, 462 
nasal transverse, 459 
Vein or veins, temporo-maxil- 
lary, 459 
of thoracic wall, 470 
thyroid, inferior, 462 
middle, 462 
superior, 462 
transverse cervical, 460 
facial, 460 
nasal, 459 
of Trolard, 468 
of upper limb, deep, 470 
superficial, 468 
ulnar, anterior, 469 
Vesicle, encephalic, 500 
germinal, 826 
seminal, 808 
umbilical, 83 
Vesico-pubic muscle, 787 
Vesicula prostatica, 790 
Vessels of liver, 739, 745 , 
Vestibule, 839 
of nose, 663 
of osseous labyrinth, 673 
Vestibulum oris, 699 
Vibrissse, 663 
Vicq-d’Azyr, bundle of, 522 
Vidian artery, 401 
nerve, 579 
Vieussens, valve of, 540 
Villi, 719 
chorionic, 84 
Vitelline membrane, 825 
veins, 93 
Vitellus, 826 
Vitreous humor, 689 
lamina, 684 
Vocal cords, false, 770 
true, 770 
Vomer, 184 
Vulva, 837 
Vulvo-vaginal glands, 841 
oblique, 455 
obturator, 480 
occipital, 460, 463 
ophthalmic, 467 
common, 467 
inferior, 467 
superior, 467 
ovarian, 475 
palpebral, inferior, 459 
parotid, 459, 460 
of pelvis, 479 
portal, 477, 739 
system of, 477 
popliteal, 482 
posterior anastomotic, 468 
auricular, 460 
facial, 459 
interventricular, 456 
temporal, 463 
ulnar, 469 
pulmonary, 454 
pudic, external, 481 
internal, 480 
pyloric, 479 
radial, 469 
posterior, 469 
vertebral, 462 
anterior, 462 
bodies, 472 
posterior, 463 
Velum interposition, 526 
pendulum palati, 700 
posterior medullary, 546 
Vena azygos major, 471 
minor, 472 
cava, ascending, 474 
descending, 456 
inferior, 474 
superior, 456 
-cava! fissure, 743 
hemiazygos, 472 
accessoria, 472 
ranine, 461 
right coronary, 456 
marginal, 456 
sacral, lateral, 480 
portae, 477 
Venae basis vertebrarum, 472 
comites, 455 
cordis minimse, 456 
Thebesii, 456 
vorticosae, 682 
Ventral pyramids, 545 
Ventricles of brain, development 
of, 103 
fourth, 550 
of larynx, 773 
right,‘36B 
Ventricular cavity, general, 504 
Vermis, 542 
inferior, 543 
superior, 542 
Vertebra dentata, 117 
prorninens, 117 
typical, 115 
Vertebrae, cervical, 116 
development of, 91 
false, 115 
Walls of cerebro-spinal axis, 505 
Weber, gland of, 734 
Wharton, duct of, 736 
White commissure, basal, 518 
of spinal cord, 554 
fibro-cartilage, 51 
fibrous tissues, 46 
Willis, circle of, 408 
Windpipe, 757 
Winslow, foramen of, 751 
Wolffian body, 99 
duct, 98 
Womb, 829 
Worm, 542 
Wormian bones, 190 
Wrisberg, nerve of, 612 
Wrist-joint, 224 
W. 
middle, 476 
saphenous, external, 481 
internal, 481 
long, 481 
short, 481 
sciatic, 480 
short saphenous, 481 
small coronary, 456 
spermatic, 475 
of spinal cord, 473 
of spine, 472 
dorsal, 472 
anterior longitudinal, 472 
longitudinal, anterior, 472 
posterior, 473 
posterior longitudinal, 473 
splenic, 479 
striate, inferior, 468 
subclavian, 470 
subcutaneous, 455 
sublobular, 740 
superficial, 455 
circumflex iliac, 481 
epigastric, 481 
temporal, 459 
superior intercostal, 471 
mesenteric, 479 
thyroid, 462 
supraorbital, 459 
suprascapular, 460 
of surface of cranium and face 
457 
lumbar, 119 
ossification of, 124 
peculiar, 118 
Xiphoid process, 126 
X. 
Y. 
sacral, 120 
serial morphology of, 125 
thoracic, 117 
Yellow fibro-cartilage, 52 
fibrous tissues, 47 
spot, 687 
true, 115 
Vertebra! artery, 406 
bodies, veins of, 472 
column, 115 
Z. 
articulations of, 205 
fascia, 358 
Zinn, ligament of, 690 
zonula of, 689 
Sylvian, deep, 468 
systemic, 455 
temporal, anterior, 463 
common, 459 
middle, 459 
posterior, 463 
superficial, 459 
grooves, 124 
veins, anterior, 462 
posterior, 463 
Verumontanum, 790 
Vesica fellea, 746 
Vesical artery, 434 
plexus, 480, 648 
Vesicle, blastodermic, 80 
Zona incerta, 536 
pellucida, 826 
Zone, ciliary, 684 
Zonula of Zinn, 689 
Zygoma, 172 
Zygomatic fossa, 191 
Zygomaticus muscle, major, 346 
minor, 346