TEXT-BOOK OF » Anatomy and Physiology FOR NURSES COMPILED BY DIANA CLIFFORD KIMBER Graduate of Bellevue Training School ; formerly Assistant Superintendent New York City Training School for Nurses, Blackwell's Island, N.Y.; formerly Assistant Superintendent Illinois Training School, Chicago, III. THIRD EDITION REVISED BY CAROLYN E. GRAY, R.N. Assistant Superintendent, New York City Training School for Nurses, Blackwell's Island, N.Y. Neto THE MACMILLAN COMPANY 1911 All rights reserved Copyright, 1898, By MACMILLAN AND CO. Copyright, 1902, 1909, By THE MACMILLAN COMPANY. Set up and electrotyped. Published September, 1894. Reprinted November, 1894; February, August, 1895; January, November, 1896; July, December, 1897; September, 1898; July, 1899; February, October, 1900; March, 1901. New edition, revised, printed February, October, 1902; February, October, 1903; June, 1904; January, October, 1905; January, 1906; January, October, 1907; January, July, 1908. New, and completely revised edition, published September, 1909. Reprinted October, 1909 ; August, 1910 ; March, 1911. NorinoolJ ^rrss J. S. Cushing Co. -Berwick & Smith Co. Norwood, Mass., U.S.A. ^tffectionatdg SDctncatEb TO MY FRIEND, SCHOOLMATE, AND SUPERINTENDENT iloutsc Warclje GRADUATE OF BELLEVUE TRAINING SCHOOL AND SUPERINTENDENT NEW YORK CITY TRAINING SCHOOL Blackwell's island, n.y. REVISER'S PREFACE TO THIRD EDITION During the seven years that have elapsed since the appear- ance of the second edition of this work in 1902, the advance in the sciences of anatomy and physiology has made it desir- able to make many changes in the text. It has also been deemed advisable to improve the quality of the illustrations and largely to increase their number. In the preparation of this new edition a number of teachers in training schools for nurses have been consulted, both per- sonally and by correspondence. Many of their suggestions have been carried out. The nomenclature adopted by the German Anatomical Society at Basle in 1895 has been introduced in this edition as far as was practicable. The new terms now generally adopted by physicians have been incorporated in the text, the old terms being given in brackets or explanatory notes. A preliminary chapter has been added for the special benefit of those students who have not studied chemistry. A chapter on "Special Membranes and Glands" has also been added, containing much new material. The chapter on the nervous system has been entirely rewritten by Howard D. Collins, M.D., who has also supervised the entire revision of the book. His criticism and advice have proved of the greatest value. To each chapter has been added a summary which it is hoped will prove of much value, both to teacher and student. The glossary and index have also been much enlarged. No pains have been spared to obtain the best illustrations available. There are about sixty illustrations in the text not included in the previous editions, and in many instances new plates and cuts have been substituted for those now out of date. I wish to express my acknowledgments to the following persons for their assistance in the preparation of this edition: Miss Theodora H. LeFebvre, R.N., assistant superintendent of Hackley Hospital, Muskegon, Michigan; Miss Jane M. V VI REVISER'S PREFACE TO THIRD EDITION Pindell, R.N., superintendent of the New York City Training School at Blackwell's Island; Miss Florence R. Corbett, Dieti- tian of Department of City Charities ; and to numerous teachers in training schools who have been most generous in giving me the benefit of their experience and advice. I also have to thank the Hon. Robert W. Hebberd, Commissioner of Public Charities of New York City, for his kind cooperation in allow- ing those who are employed in the New York City Training School to assist in the work of revision. In the list of illustrations credit is given to the various works from which they are borrowed. To the publishers mentioned in that list I wish to express my obligations for their permis- sion to use such illustrations. Above all, I wish to express my indebtedness to those authors whose works I have consulted. In many cases I have freely drawn upon them for the new material in the revision. A list of these authors and their books appears in the bibliography on page 421. Miss Kimber having been unable to undertake this revision, as a former pupil of the author I have taken pride in being -asked to act in her stead. I trust the new edition will meet with as favourable a reception as its predecessors. C. E. G. July, 1909. TABLE OF CONTENTS PAGE Physical, Chemical, and. Biological Definitions and Explanatory Notes . 1 I. Definitions. - Names of Surface Parts. - General Outline of the Body ............ 15 II. Structural Units of the Body: Cells, Tissues, Organ, System. - Epithelial Tissue: Stratified, Transitional, Simple . . 23 III. Connective Tissues: Areolar, Fibrous, Elastic, Adipose, Reticular, Lymphoid, Cartilage, Bone 33 IV. The Skeleton ........... 47 V. Articulations........... 79 VI. Muscular Tissue : Striated, or Striped ; Non-striated, or Plain ; Attachment of Muscles to Skeleton ; Prominent Muscles of Head and Trunk ; Prominent Muscles of Limbs ... 86 VII. Special Membranes and Glands 120 VIII. The Vascular System; the Blood . . . . . . . 134 IX. The Vascular System Continued: Heart; Arteries; Capillaries; Veins............ 146 X. The Vascular System Continued: Arterial Distribution and Ve- nous Return .......... 161 XI. The Vascular System Continued: The General Circulation; the Pulse and Arterial Tension ; Variations in the Capillary Circu- lation ; Foetal Circulation 186 XII. Vascular System Concluded : Lymph and Lymphatic Vessels. - Lymph nodes and Bodies of Allied Structure. - Ductless Glands 199 XIII. The Respiratory Apparatus: Larynx; Trachea; Bronchi and Lungs. - Respiration. -The Effect of the First Respirations.- Capacity of the Lungs.-The Effect of Respiration upon the Air outside the Body, upon the Blood. - Modified Respiratory Movements . 219 XIV. The Digestive Apparatus: Alimentary Canal and Accessory Organs 236 XV. Digestion: Changes the Food undergoes in the Mouth, Stomach, Small and Large Intestine ; Absorption 262 XVI. Elimination ; Description of the Organs constituting the Urinary System ; General Characters of Urine; Secretion of Urine . 274 XVII. Elimination Concluded: The Skin and its Appendages.-Bodily Heat; Production of Heat; Loss of Heat; Distribution of Heat; Regulation of Heat 289 XVIII. The Nervous System 302 XIX. Common Sensations and the Special Senses: Touch, Taste, Smell, ' Hearing, and Sight 336 XX. Female Generative Organs 367 Glossary . 387 Bibliography 421 Index 423 VII LIST OF ILLUSTRATIONS FIG. PAGE 1. Side view of cranium and face. (Gerrish) 15 2. Front view of a man in the anatomical position. (Gerrish) . . 16 3. Back view of a man. (Gerrish) 17 4. Front of torso of a woman. (Gerrish) 18 5. Diagrammatic longitudinal section of the trunk and head ... 19 6. Position of the thoracic and abdominal organs (front view). (Morrow) 20 7. Position of the thoracic and abdominal organs (rear view). (Morrow) 21 8. Diagram of a cell ....... ... 23 9. A to H, consecutive stages of cell-division, with indirect division of the nucleus. (Diagrammatic) .....*. 24 10. Section of stratified epithelium. (Schafer) 28 11. Section of the transitional epithelium lining the bladder. (Schafer) . 29 12. Simple pavement epithelium 29 13. Simple columnar epithelium ......... 30 14. Glandular epithelium, with the cells set round a simple saccular gland (Flemming) 30 15. Ciliated epithelium from the human trachea . . . .30 16. Subcutaneous areolar tissue from a young rabbit. (Schafer) . . 34 17. Fibrous tissue, from the longitudinal section of a tendon. (Gegenbauer) 35 18. A few fat cells from the margin of a fat lobule. (Schafer) . . 37 19. Retiform tissue from a lymph node. (Quain) 39 20. Articular hyaline cartilage from the femur of an ox. (Ranvier) . 39 21. Vertical section of a long bone. (Gerrish) 42 22. Diagram of the structure of osseous tissue. (Gerrish) . . .43 23. The human skeleton. (Morrow) 49 24. Side view of the skull. (Morrow) 50 25. Front view of the skull. (Morrow) 51 26. Occipital bone 52 27. Parietal bone 53 28. Frontal bone . . . . . . . . . . . .53 29. The right temporal bone. (Gerrish) ....... 54 30. Parietal, temporal, and sphenoid bones. (Gould's Dictionary) . . 55 31. Ethmoid bone . 55 32. Skull of new-born child. (Edgar) 56 33. Skull of new-born child. (Edgar) 56 34. Nasal bones. (Gerrish) ......... 57 35. Lacrimal bone 57 36. Sagittal section of face, a little to the left of the middle line, showing the vomer and its relations. (Gerrish) 58 37. Right malar bone. (Gerrish) 58 38. The two palate bones in their natural position. (Gerrish) ... 59 IX X LIST OF ILLUSTRATIONS FIG. PAGE 39.. Right inferior turbinate bone. (Gerrish) ...... 59 40. The right maxilla. (Gerrish) .59 41. The mandible. (Gerrish) 60 42. The hyoid bone. (Gerrish) 60 43. The vertebral column. (Gerrish) 61 44. A cervical vertebra 62 45. The atlas. (Gerrish) 63 46. The epistropheus. (Gerrish) 63 47. Thorax 64 48. The sternum. (Gerrish) 65 49. The eighth rib of the right side. (Gerrish) 66 50. The right clavicle. (Gerrish) 67 51. The scapula, or shoulder blade. (Morrow) ..... 67 52. The humerus, or arm bone. (Morrow) 68 53. The bones of the forearm. (Morrow) 69 54. The bones of the right hand. (Gerrish) 71 55. Development of the hip bone. (Gerrish) 72 56. The femur, or thigh bone. (Morrow) 73 57. The patella, or knee-cap. (Morrow) 73 58. The bones of the leg. (Morrow) 74 59. The bones of the right foot. (Gerrish) • 75 60. Female pelvis 76 61. Male pelvis 76 62. A toothed, or dentated suture 79 63. Diameters and landmarks of the fcetal skull. (Edgar) ... 80 64. Diameters and landmarks of the foetal skull. (Edgar) ... 81 65. A slightly movable joint 81 66. A complete joint .82 67. Diagram of muscle-fibre with sarcolemma attached . . . . 87 68. Wave of contraction passing over a muscular fibre of Dytiscus. (Schafer) 88 69. Fibre-cells of plain muscular tissue 88 70. Forms of muscles and tendons 90 71. Superficial muscles of head and neck. (Gerrish) .... 92 72. Muscles of right eyeball within the orbit 93 73. Muscles of eyeball .......... 93 74. Temporal and deep muscles about the mouth. (Gerrish) ... 94 75. Pterygoid muscles. (Gerrish) 95 76. Muscles of the tongue. (Gerrish) 95 77. The ligamentum nuchse. (Gerrish) 97 78. Muscles in the superficial layer of the back. (Gerrish) ... 98 79. Front of chest and shoulder of right side, superficial muscles. (Gerrish) 99 80. Intercostal muscles in right wall of thorax. (Gerrish) ... 99 81. Diaphragm. (Gerrish) 100 82. Rectus abdominis and obliquus internus of right side. (Gerrish) . 102 83. Transversalis abdominis of right side. (Gerrish) .... 103 84. Muscles of the front of the right shoulder and arm. (Gerrish) . . 104 85. Muscles of the dorsum of the right shoulder and arm. (Gerrish) . 105 86. Muscles in the dorsum of the right forearm and hand. (Gerrish) . 106 87. Gluteus maximus of right side. (Gerrish) 107 LIST OF ILLUSTRATIONS XI FIG. x PAGE 88. Psoas, iliacus, and obturator externus muscles. (Gerrish) . . 108 89. Muscles in the dorsum of the right thigh. (Gerrish) .... 109 90. Superficial muscles in front part of the right thigh. (Gerrish) . . 109 91. Vastus intermedins of right side. (Gerrish) . . . . .110 92. Gastrocnemius of right side. (Gerrish) Ill 93. Nerve-ending in muscular fibre of a lizard. (Kuhne) . . .112 94. Portion of endothelium of peritoneum. (Klein) .... 120 95. Diagram of the gastro-pulmonary mucous membrane, showing the continuity of all its parts. (Gerrish) 124 96. An intestinal villus 126 97. The anterior annular ligament of the ankle and the synovial mem- branes of the tendons beneath it artificially distended. (Gerrish) 128 98. Diagram showing various forms of secreting glands .... 129 99. Red and white corpuscles of the blood 136 100. Bowl of recently coagulated blood, showing the whole mass uniformly solidified. (Collins) ......... 141 101. Bowl of coagulated blood after twelve hours, showing the clot con- tracted and floating in the fluid serum. (Collins) . . .141 102. Heart in situ 147 104. Anterior view of the heart, dissected, after long boiling, to show the superficial muscular fibres. (Quain) ...... 149 105. Diagram of heart and serous pericardium 149 107. Cross-section through both ventricles, showing the shape of their cavities and the relative thickness of their walls. (Gerrish) . 151 109. Aortic valve. (Gerrish) 152 110. Diagram of a cross-section of an artery, showing the composition of its tunics. (Gerrish) 156 111. Fine capillaries from the mesentery. (Collins) 157 112. Diagram showing valves of veins. (Sharpey) 158 113. Diagram showing the branchings, anastomoses, and confluence of arteries. (Gerrish) 161 132. Diagram of the circulation. (Collins) 187 133. Diagram of circulation before birth. (Cooke) 194 134. Isolated capillary network formed by the junction of several hollowed- out cells, and containing coloured blood-corpuscles in a clear fluid. (Schafer) 196 135. Lacteals and lymphatics, during digestion. (Collins) . . . 202 136. A small portion of a lymphatic plexus. (Schafer) .... 203 137. Valves of the lymphatics. (Flint) 203 140. Lymphatic and thoracic ducts. (Gerrish) 206 141. A lymph node with its afferent and efferent vessels. (Gerrish) . 208 143. Mucosa of small intestine in ideal vertical cross-section. (Gerrish) . 210 144. Aggregated lymph nodule. (Gerrish) 211 148. Diagram of the essentials of a respiratory apparatus. (Gerrish) . 219 149. Larynx. (Gerrish) 220 150. The larynx, as seen by means of the laryngoscope in different condi- tions of the glottis 221 151. Front vieyv of cartilages of larynx 222 152. Bronchi and bronchioles. (Gerrish) ....... 224 154. Regions of the abdomen. (Gerrish) 238 XII LIST OF ILLUSTRATIONS FIG. PAGE 155. Sagittal section of the face and neck, showing the first portions of the alimentary and respiratory tracts. (Gerrish) .... 239 156. The soft palate and tonsillar regions. (Gerrish) .... 240 157. The salivary glands 241 158. Section of human molar tooth. (Collins) 242 159. The stomach and intestines, front view, the great omentum having been removed, and the liver turned up and to the right. (Gerrish) 245 160. Portion of small intestine laid open to show circular folds. (Collins) 248 161. An intestinal villus .... 248 162. Portion of the mucous membrane, from the ileum. (Collins) . . 249 163. Cavity of the ctecum, its front wall having been cut away. (Gerrish) 250 164. Ducts of the pancreas. (Gerrish) 252 165. The liver. (Gerrish) 253 166. The liver. (Gerrish) 254 167. Diagrammatic representation of two hepatic lobules .... 255 168. Lobule of rabbit's liver, vessels and bile-ducts injected . . . 257 16p. Vertical section of the kidney. (Collins) 276 170. Diagram of the course of two uriniferous tubules .... 277 171. Vascular supply of kidney 278 172. Plan of the blood-vessels connected with the tubules . . . .279 173. Diagram showing method of entrance of the ureter into the bladder (Gerrish) 280 174. Vertical section through the skin of the palmar side of the finger, showing two papillae (one of which contains a tactile corpuscle) and the deeper layer of the epidermis. (Schafer) . . . 290 175. Thumb-nail. (Gerrish) 292 176. Piece of human hair 292 177. Vertical section of the skin, showing sebaceous glands, sweat-glands, hair and follicle ; also arrector muscle. (Gerrish) . . . 294 178. Coiled end of a sweat-gland 295 179. Neurone. (Collins) 303 180. Nerve-fibres 304 181. Sensory nerve terminations in stratified pavement epithelium. (Kirkes) 306 182. Pacini's corpuscle. (Collins) 306 183. Tactile corpuscle and nerve. (Collins) 307 184. Section of the internal saphenous nerve 308 185. Diagram illustrating the general arrangement of the cerebro-spinal system • . . 309 186. General view of the sympathetic system 311 187. Diagram showing the relation of the cerebro-spinal to the sympathetic neurones ..... . 312 188. Base of brain, spinal cord, and spinal nerves 313 189. Transverse sections of the spinal cord at different levels. (Gowers) . 314 190. Diagram of nerve roots emerging from spinal cord. (Collins) • . 315 191. Degeneration of spinal nerves and nerve roots after section . . 317 192. The base of the brain 320 193. External view of outer side of right cerebral hemisphere, showing Rolando, Sylvian, and parieto-occipital fissures, together with principal convolutions. (Collins) 322 LIST OF ILLUSTRATIONS XIII FIG. PAGE 194. Mesial view of left cerebral hemisphere, showing Rolandic and parieto- occipital fissures, together with the principal convolutions. (Collins) ' 322 195. Reflex arc. (Collins) 330 196. Diagram of nervous system • 332 197. The upper surface of the tongue. (Sappey) 340 198. Vertical longitudinal section of nasal cavity 342 199. Semi-diagrammatic section through the right ear .... 344 200. Ossicles of the tympanum. (Flint) 345 201. The left bony labyrinth of a new-born child, forward and outward view. (Flint) 347 202. Diagram showing relative position of the planes in which the semi- circular canals lie ......... . 349 203. The lacrimal apparatus 351 204. Diagrammatic section of the eye. (Flint) 352 205. Segment of the iris, ciliary body, and choroid. (Gerrish) . . 354 206. Choroid membrane and iris exposed by the removal of the sclera and cornea. (Collins) 355 207. Diagrammatic section of the human retina. (M. Schultze) . . 356 208. The posterior half of the retina of the left eye viewed from before. (Collins) ........... 357 209. Diagram illustrating rays of light converging in a normal eye, (A'), a myopic eye, (R), and a hypermetropic eye (O') .... 359 210. Uterus, uterine tubes, and ovaries. - Posterior view. (Sappey) . 368 211. Internal organs of generation. (Cooke) 372 212. Sagittal section of the vagina and neighbouring parts. (Gerrish) . 375 LIST OF COLOURED ILLUSTRATIONS FIG. PAGE 103. The pulmonary artery and aorta. (Gerrish) 148 106. Left auricle and ventricle, the hind' wall of each having been removed (Gerrish) 150 108. Valves of the heart and great arteries, viewed from above, the auricles having been removed. (Gerrish) 151 114. The principal arteries and veins of the body. (Morrow) . . . 163 115. Thoracic aorta. (Gerrish) 164 116. Abdominal aorta. (Gerrish) 165 117. Axillary and subclavian arteries. (Gerrish) 167 118. Deep anterior view of the arteries of the arm, forearm, and hand . 168 119. Superior mesenteric artery. (Gerrish) . . . . .170 120. Inferior mesenteric artery. (Gerrish) 171 121. Femoral artery. (Gerrish) . 172 122. Arteries in the dorsal part of the leg. (Gerrish) . . . .173 123. Anterior tibial artery. (Gerrish) 174 124. Arteries of the dorsum of the foot. (Gerrish) 175 125. Pulmonary veins, seen in a dorsal view of the heart and lungs. (Gerrish) 176 126. Veins of the neck and upper part of thorax. (Gerrish) . . . 178 127. Superficial veins of the front of the leg and foot. (Gerrish) . . 179 128. Superficial veins of the front of the right thigh. (Gerrish) . . 179 129. Superficial veins of the dorsum of the leg. (Gerrish) . . . 180 130. Portal system of veins. (Gerrish) 181 131. Azygos and intercostal veins. (Gerrish) 182 138. The nodes and vessels of the upper limb. (Gerrish) .... 204 139. The nodes and vessels of the lower limb. (Gerrish) .... 205 142. The lymph nodes of the neck and upper part of the thorax. (Gerrish) 209 145. The spleen, showing the gastric and renal surfaces and the blood- vessels. (Gerrish) 212 146. The thyroid body and the related blood-vessels. (Gerrish) . . 213 147. The thymus, the sternal and costal cartilages having been removed. (Gerrish) 214 153. Diagram of a lobule of the lung 225 XV LIST OF BOOKS FROM WHICH ILLUSTRATIONS HAVE BEEN BORROWED Essentials of Histology, by E. A. Schafer, Longmans, Green & Co., New York. Handbook of Physiology, by Austin Flint, M.D., The Macmillan Co., New York. Illustrated Dictionary of Medicine, Biology, and Allied Sciences, by George M. Gould, M.D., P. Blakiston's Son & Co., Philadelphia. Immediate Care of the Injured, by Albert S. Morrow, M.D., W. B. Saunders Co., Philadelphia. Kirkes's Handbook of Physiology, revised by Wm. H. Rockwell, M.D., and Chas. L. Dana, M.D., Wm. Wood & Co., New York. Nurse's Handbook of Obstetrics, by Joseph Brown Cooke, M.D., J. B. Lippincott Co., Philadelphia. Physiology, by Howard D. Collins, M.D., and Wm. H. Rockwell, M.D., Lea & Febiger, Philadelphia. Text-book of Anatomy by American Authors, edited by Frederic Henry Gerrish, M.D., Lea & Febiger, Philadelphia. The Practice of Obstetrics, by J. Clifton Edgar, M.D., P. Blakiston's Son & Co., Philadelphia. XVI ANATOMY AND PHYSIOLOGY FOR NURSES PRELIMINARY CHAPTER PHYSICAL, CHEMICAL, AND BIOLOGICAL DEFINI- TIONS AND EXPLANATORY NOTES It is our purpose to incorporate in this chapter definitions and explanatory notes taken principally from the writings of the foremost present-day authorities on scientific matters, indicat- ing what is at present regarded as true of the relation of Matter and Energy to the human body. 1. THE THREE ULTIMATE ENTITIES (OR THINGS) ARE (a) Matter is anything which occupies space and possesses weight. Thus, wood, water, copper, oil, and air are forms of matter, for they evidently possess weight and fill space. But light, heat, electricity, and magnetism we cannot consider to fill so many quarts or to weigh so many pounds. These last, therefore, are forms of non-matter. (Duncan.) (6) Energy is that which causes change in matter. (Rem- sen.) The power to change the state of motion of a body is energy. (Duncan.) As examples of different forms of energy we have heat, light, motion, electricity, magnetism, etc. (c) Ether, the medium which fills the universe. Not only through interstellar spaces, but through the world also, in all its manifold complexity through our own bodies; all lie not only encompassed by it, but soaking in it as a sponge lies soaked in water. (Duncan.) 2. THE COMPOSITION OF MATTER Matter exists in two states:-• (a) Elements are substances from which, with the means now at the disposal of chemists, it is impossible to get simpler sub- stances. (Remsen.) An Element is a substance that has, so 1 2 ANATOMY FOR NURSES far, resisted all attempts to decompose it (or separate it into simpler substances); its molecule (see paragraph 3) contains only one kind of atom (see paragraph 3); of these elementary bodies there are some seventy1 in all. Their properties, as ele- ments, do not resemble the substances which they form when united chemically with one or more other elements. Some of them, such as iron, sulphur or phosphorus, may exist free or combined; others, such as calcium, caesium, or fluorine, are always combined, and you never see them as elements. (6) Compounds. - A Compound is a substance that may be decomposed (or separated) into other substances; its molecule contains two or more kinds of atoms. (Duncan.) The same chemical compound always contains the same elements in the same proportion of weight. A compound is thus understood to be a substance formed by the chemical combination of two or more elements, the new substance or'compound thus formed having properties different from those of the elements of which it is composed. For example, hydrogen and oxygen are both gases under ordinary temperature, but combined chemically (H2O), they form water, which is a liquid under ordinary tem- perature. Chemical Compounds must be distinguished from Mechanical Mixtures. "Complex substances which may be separated into their components by purely mechanical processes are called mechanical mixtures; thus granite is a mechanical mixture of three chemical compounds (the minerals feldspar, mica, and quartz). Air is a mechanical mixture consisting mainly of the two elements nitrogen and oxygen." (Remsen.) 3. THE STRUCTURE OR CONSTITUTION OF MATTER Matter exists in the form of small particles. These are of two forms, Molecules and Atoms. (a) A Molecule is the smallest particle of a substance that can exist in a free state, and which has the same composition as any larger mass of substance. (Duncan.) The elements themselves are believed to consist of molecules which are in turn made up of atoms of the same kind. The molecule of the 1 Between seventy and eighty elements are believed to exist. CHEMICAL AFFINITY 3 compound consists of atoms of different kinds, while the molecule of an element consists of atoms of the same kind, or in a few cases of one atom. (Remsen.) Illustration of the nature of the molecule: we believe that, taking, for example, a piece of common salt, if we proceeded to break it up finer and finer, we should eventually, away down in the scale of fineness, arrive at a piece so small that, if it were broken in two, we should have no longer two pieces of salt resulting, but instead, two particles widely different in their properties; namely, a piece of the metal sodium and a piece of the gas chlorine. This piece of salt, so small that if we broke it the pieces would no longer have the properties of salt, is called a molecule, of salt. (Duncan.) (b) An Atom is the smallest particle of an element that exists in any molecule. (Duncan.) Atoms are the smallest particles of the elements that take part in chemical reactions (see foot- note, page 5), and are for the greater part incapable of existence in the free state, being generally found in combination with other atoms, either of the same kind or of different kinds. The smallest particles of the molecules are the atoms. The molecules of the compounds are made up of the atoms of the elements. (Remsen.) Illustration of the relation of the atom to the molecule: a (chemical) substance is X molecules, and a mole- cule is a little building of which the atoms are the bricks. We believe that everything in God's universe of world and stars is made of atoms, in quantities X, Y, or Z respectively. Men and women, mice and elephants, the red belts of Jupiter and the rings of Saturn are one and all, but ever shifting, ever vary- ing, swarms of atoms. Every chemical work of earth, of air, fire, and water, every criminal act, every human deed of life or valor, - what is it all, pray, but the relation of one swarm of atoms to another? (Duncan.) 4. CHEMICAL AFFINITY Chemical affinity is the force that causes the chemical com- bination of the atoms and molecules of matter. All chemical changes which are taking place around us may be referred to the operation of chemical affinity. If this power should cease to operate, what would be the result? Nature would be in- finitely less complex than it now is. All complex substances 4 ANATOMY FOR NURSES would be resolved into the elements of which they are com- posed, and, as far as we know, there would be only about seventy different kinds of substances. All living things would cease to exist, and in their places there would be three invisible gases and something very much like charcoal. Mountains would crumble to pieces, and all water would disappear, giving two invisible gases. The processes of life in its many forms would be impossible, as, however subtle that which we call life may be, we cannot imagine it to exist without the existence of certain complex forms of matter; and as regards the life processes of animals and plants, most complex chemical changes are con- stantly taking place within them, and these changes are essential to the continuance of life. (Remsen.) The strength of chemi- cal affinity varies greatly, and hence in some substances the molecules can only with great difficulty be broken up into their component atoms. Such substances are said to be "stable" (examples: feldspar and mica, which contain aluminum). On the other hand, many substances are very easily decomposed and are known as 11 unstable" substances (examples: milk, eggs, meat, fish). Between these two extremes there are substances possessing every degree of stability. 5. OXIDATION Oxidation is the process of the element oxygen combining chemically with other substances, heat and light being evolved in the process. The heat and light evolved may not be per- ceptible unless the oxidation takes place rapidly, as in the burn- ing of gas, wood, coal, etc. If the substance combines slowly with oxygen, light is not seen, and heat may be imperceptible; for example, iron allowed to lie in moist air is covered with rust due to the union of the iron and oxygen. Also in our bodies much of the food which we take unites with oxygen, and thus the temperature of the body is kept up, but light is not per- ceptible. It is for this reason that oxygen must be taken into the body, which is accomplished by the act of breathing. It is also for this reason essential that the air we breathe in, should have its full complement of oxygen, or 23 per cent. To insure this a constant supply of pure, fresh air is imperative. CHEMICAL ELEMENTS FOUND IN HUMAN BODY 5 6. CHEMICAL ELEMENTS FOUND IN HUMAN BODY The elements found in the body are: - Carbon, 13.5 (C) Hydrogen, 9.1 (H) Nitrogen, 2.5 (N) Oxygen, 72. (O\ form 97 per cent of total weight of body. Sulphur, (S) Phosphorus, (P) Fluorine, (F) Chlorine, (Cl) Iodine, (I) Silicon, (Si) Sodium, (Na) Potassium, (K) Calcium, (Ca) Magnesium, (Mg) Lithium, (Li) Iron, (Fe) Manganese, (Mn) Copper, (Cu) Lead, (Pb)1 1 It is convenient to use abbreviations for the names of the elements and compounds; thus, instead of oxygen, we may write symbol O; for hydro- gen, H; for nitrogen, N, etc. Whenever the symbols of the elements are placed side by side with no sign between them (for example, HC1, H2O, and NaOH), the resulting formula means that the elements are in chemical combination. In dealing with cases of chemical action it is desirable to express by means of symbols and formulae what takes place. In general, a chemical change is called a chemical reaction. Examples of this are found in the combining of elements to form compounds, or the breaking up of compounds into simpler compounds or elements. Thus, if carbon (C) burns in the air, it combines with oxygen; the reaction is represented as follows: - C + O2 = CO2. The new substance formed (CO2) is carbon dioxide. The small figures used in the formulae of certain compounds (H2O, Fe2Cle) indicate the number of atoms of the element which enter into combination with the other elements indicated to form the molecule of the compound. Thus, in Fe2Cle (ferric chloride) two atoms of iron have com- bined with six atoms of chlorine to form the molecule indicated by the formula Fe2Cle. 6 ANATOMY FOR NURSES Of these, very few occur in the free state. Oxygen (to a small extent) and nitrogen are found dissolved in the blood-plasma; hydrogen is formed by putrefaction in the alimentary canal. With some few exceptions such as these, the elements enumerated above are found combined with one another to form compounds. (Halliburton.) 7. COMPOUNDS OF MATTER WHICH CONSTITUTE OUR FOOD AND OF WHICH THE TISSUES OF THE HUMAN BODY ARE FORMED The human body, from a chemical point of view, may be regarded as a mixture of three large classes of chemical sub- stances; that is, proteids, fats, and carbohydrates, associated with water and mineral salts. These compounds, which con- stitute in a general way the tissues of the human body and which in various combinations constitute our foods, are known as the Proximate Principles, or Five Food Principles: - 1. Water, found in all foods and in all tissues and fluids of the body. It is a compound of oxygen and hydrogen, water being produced whenever two atoms of hydrogen unite with one of oxygen. Next to air, water is the most necessary principle of life. It forms about 70 per cent of the entire bodily weight; it acts as a solvent upon various ingredients of the food, liquefy- ing them and rendering them capable of absorption. Most of the water of the body is taken into it from without, but it is also formed within the body by chemical action in the tissues. 2. Mineral salts. - The mineral substances chiefly necessary for nutrition are: - Chloride Phosphate Sulphate Carbonate of sodium and potassium. Phosphate Carbonate of calcium and magnesium. Of these substances, chloride of sodium, sodium chloride, or common salt, is the most important mineral ingredient of food. It is contained in nearly everything we eat. It is present in most of the fluids of the body, notably in the blood. The rest COMPOUNDS OF MATTER 7 of the mineral substances are usually contained in sufficient quantity in an ordinary diet, though occasionally it becomes necessary to supply them independently. Of all the mineral salts, phosphate of calcium exists in the largest quantity in the body; it enters largely into the composition of the bones, teeth, and cartilages, and gives firmness and solidity to the tissues. It is present in very small quantities in the bodily fluids, with the exception of the milk, which contains a notable amount of phosphate of calcium, which serves for the ossification of the growing bones of infants. 3. Carbohydrates are compounds of hydrogen, oxygen, and carbon, the hydrogen and oxygen being combined in the pro- portion to form water. The principal carbohydrates are starches and sugars. Starch is found in wheat, Indian corn, oats, and all grains, in potatoes, peas, beans, roots and stems of many plants, and in some fruits. In a pure state, it appears as a white powder, as in arrowroot and corn-starch. Under the influence of dry heat, starch may be converted into a soluble substance called dextrine; and, under the action of certain of the digestive juices, at the temperature of the body, into sugar. Of sugars there are several kinds: - Cane sugar, or sucrose, obtained chiefly from the sugar-cane; Beet sugar; Maple sugar; Grape sugar, or glucose, found in grapes, peaches, and other fruits (it is also readily manufactured from starch); Malt sugar, or maltose, obtained from malt; Milk sugar, or lactose, obtained from milk. Carbohydrates are readily oxidized; together with fats, they are often classed as " non-nitrogenous " food-stuffs. The carbo- hydrates are found chiefly in vegetable tissues. Some are, how- ever, found in or formed by the animal organism. The most important of these are: - Glycogen, or animal starch; Dextrose, or glucose; Lactose, or milk sugar; Maltose.1 1 These sugars represent different forms of the carbohydrates ingested, which result at different stages of digestion. 8 ANATOMY FOR NURSES 4. Fats. - Fats are composed of carbon, hydrogen, and oxygen. The most important fats are:-■ Stearin, Palmatin, Margarin, Olein, which exist in varying proportions in the fat of animals and vegetable oils, and in milk, butter, lard (and other foods and vegetable substances, as olives, sweet almonds, chocolate, castor oil bean, hemp, and flaxseed). Lecithin is a very complex fat, found to a great extent in the nervous system, to a small extent in bile, the brains of animals, and the yolk of eggs. The contents of the fat cells of human adipose tissue are fluid during life, the normal temperature of the body, 98° F. (37° C.) being considerably above the melting- point, 77° F. (25° C.) of the mixture of fats found there. Fats are the source of the greatest amount of heat of any of the food-stuffs. This great potential heat energy is due to the relatively small amount of oxygen compared to the carbon and hydrogen in the fat molecule (stearin is C67H110 O6). In order to completely oxidize a molecule of fat (stearin) and resolve it into the ultimate carbon dioxide (CO2) and water (H2O), it would be necessary to add one hundred and sixty-three atoms of oxygen. In symbols this might be expressed thus: C57H110O6 + O163 = C57H110O169. This, simplified to terms of car- bon dioxide and water, would equal (C57O114) (H110O55) or 57 CO2 + 55 H2O. A molecule of carbohydrate (glucose CcH12O6) is already rich in oxygen, and only needs twelve atoms of oxygen to reduce the equation to terms of carbon dioxide and water. Thus, C6H19O6 + 019 = C6H19O18 or 6 CO2 + 6 H90. Fats are stored up in the body to a greater degree than either proteids or carbohydrates; for not only are the stored-up fats obtained from the fat contained in the food, but also fat is de- rived from imperfectly oxidized proteids and carbohydrates. 5. Proteids. - Proteids form a large proportion of all living bodies, and are an essential part of all living structures. Pro- teid substances are the most stable compounds found in the body and in organic foods. The proteid compounds consist AIR 9 mainly of carbon, hydrogen, nitrogen, oxygen, with sulphur and phosphorus in small quantities only. (Halliburton.) Proteids occur in the form of: - Albumin in the white of egg (egg-albumin), milk, blood, and lymph (serum-albumin). Casein in milk and cheese; Myosin, and Syntonin in muscle; Vitellin in the yolk of eggs; Glutin in flour; Legumin in peas, beans, and lentils; and other forms in small proportion. Proteids may be oxidized in the body to yield heat and energy, but being more stable in composition than fats and carbo- hydrates, they are more often built up into tissue, and are used for fuel only in emergencies when the supply of carbohydrates or fats is insufficient. All proteids yield peptones very readily at the temperature of the body under the action of the acid gastric juice and alkaline pancreatic juice. These peptones are highly soluble bodies and readily absorbed. In the final trans- formation of proteid substances in the body they are reduced to three chief products: - (1) Carbon Dioxide. (2) Water. (3) Urea. (See Elimination, Chapter XVI.) The foods that are most rich in the various forms of proteids are broth, meat, milk, eggs, cheese, all kinds of fish, wheat, beans, and oatmeal. 8. AIR The atmosphere of the earth, commonly called the air, con- sists essentially of two elements, nitrogen and oxygen, in the proportion of seventy-nine volumes of nitrogen to twenty-one volumes of oxygen, or by weight, of 77 per cent of nitrogen and 23 per cent of oxygen. Wherever air has been collected and analyzed, it has been found to have practically the same com- position. Nevertheless, very accurate analyses have shown 10 ANATOMY FOR NURSES that the composition of the air is subject to slight variations. Nitrogen and oxygen are not combined chemically in the air, but they are simply mixed together. Other substances which are contained in the air in small propor- tion are a gaseous compound, carbon dioxide, CO2; a gas, argon; ammonia; hydrogen dioxide and organic matters of various kinds, including a large variety of germs, the presence of which can be detected by the changes which exposure to the air pro- duces in certain liquids, as milk and fruit juices. (Remsen.) 9. CARBON DIOXIDE, CO2 The principal compound of carbon and oxygen is carbon dioxide, CO2. Under the head of the Air, attention was called to the fact that this gas is a constant constituent of the air, though its relative quantity is small - about 3 parts in 10,000 (or more frequently given as 4 parts in 10,000). It issues from the earth in many places, particularly in the neigh- bourhood of volcanoes. Many mineral waters contain it in large quantity. In small quantity it is present in all natural waters. In combination with bases (see paragraph 11), it occurs in enormous quantities, particularly in the form of calcium car- bonate, CaCO3, varieties of which are ordinary limestone, chalk, marble, and calcspar. Carbon dioxide is constantly formed in many natural processes. All animals that breathe in the air give off carbon dioxide from the lungs. That the gases from the lungs contain carbon diox- ide can easily be shown by passing them through lime-water, when a precipitate of calcium carbonate is formed. Carbon dioxide is formed in the decomposition of charcoal and wood, of gas, and whenever any other combustible substances are burned. The natural processes of decay of both vegetable and animal matter tend to convert the carbon of this matter into carbon dioxide, which then finds its way into the air. The process of alcoholic fermentation and some other similar pro- cesses also give rise to the formation of carbon dioxide. Carbon dioxide is a colorless gas at ordinary temperatures. When sub- jected to a low temperature and high pressure, it is converted into a liquid. The gas has a slightly acid taste and smell. It is not combustible nor does it support combustion. (Remsen.) DEFINITIONS OF CHEMICAL TERMS 11 10. WATER - Water is a very stable chemical compound of hydrogen and oxygen, H2O. Pure water is tasteless and inodorous, and in small quantities colourless. Thick layers are, however, blue. Some mountain lakes have a marked blue colour. Water freezes at 0° C. or 32° F. . It boils at 100° C., 212° F., at normal atmospheric pressure. Water occurs in the form of liquid in enormous quantities in the earth. All living things contain a large proportion of water which can be driven off by heat. Thus, if a piece of wood or of meat is heated, liquids pass off, and by distillation these can be shown to consist mainly of water. The proportion of water in animal and vegetable substances is very great. If the body of a man weighing one hundred and fifty pounds were put in an oven and thoroughly dried, there would be only about forty pounds of solid matter left, most of the rest being water. Many substances which do not appear moist contain a large proportion of water. For example, many crystals, while ap- parently dry, contain more than half their weight of water. (Remsen.) Protoplasm (see paragraph 13) contains water to the extent of three-quarters of its own weight. (Halliburton.) Water is an almost universal solvent, that is, it is capable of dissolving and holding in solution more substances than any other liquid. This property makes it a valuable vehicle for dis- tributing digested food to the cells of the body, and for collect- ing waste products and transferring them in the body to the organs of elimination. Water forms the principal part of the blood stream where it contains in solution certain proteids, extractives, and inorganic salts, and is known as plasma. One thousand parts of blood-plasma contain over nine hundred parts of water. 11. DEFINITIONS OF CHEMICAL TERMS 1. Acid.-The term is difficult of definition. It may be defined as "a salt of hydrogen." Therefore, every acid must contain hydrogen, but every substance containing hydrogen is not necessarily an acid. 12 ANATOMY FOR NURSES 2. Salt. - Denotes the combination of an anhydride with a basic oxide. 3. Anhydride. - Means an acid from which water has been removed. 4. Basic oxide (base). - Is an oxide of one of the alkaline metals 1 or alkaline earths.2 5. Alkali. - Alkali is the oxide or hydroxide of sodium, potassium, lithium, caesium, rubidium, and ammonium. When an acid acts upon a base, the hydrogen and metal or alkaline earth exchange places. The substance formed by substituting hydrogen for the metal of the base is water. The substance obtained from the acid by substituting a metal for the hydrogen is neither an acid nor a base, but is generally a neutral substance, and is called a salt. As an illustration of the action of an acid on a base, we have caustic soda (sodium hydroxide, NaOH, the metal sodium in solution) acted upon by hydrochloric acid (HC1). The result is indicated in the following equation: - HC1 + NaOH = NaCl + H2O. common salt + water. 12. MATTER MAY BE ORGANIC OR INORGANIC Organic substances are nearly always highly complex bodies (consisting of many elements). Two particular elements, car- bon and hydrogen, enter into all organic bodies. Some organic substances are very simple chemically, and may contain no ele- ments except carbon and hydrogen. In order to be included as an organic body, the substance must have been at some time either an intimate part of, or a product of the activity of, a living body; or else either an intimate part of, or a product of the decomposition of, a body that had lived; bearing in mind, however, that the recent advances in chemical science have permitted the manufacture of organic bodies in the laboratory. Organic substances are further subdivided into those contain- ing nitrogen and those not containing nitrogen. Inorganic substances are best defined by describing them 1 Alkaline metals are sodium, potassium, lithium, caesium, rubidium. 2 Alkaline earths are barium, strontium, calcium. PROTOPLASM 13 as bodies failing to fulfil the conditions given for organic sub- stances. Carbon dioxide (CO2) is a body that fulfils all the conditions for being organic to a marked degree, except that no hydrogen is present, hence breaking the rule that both carbon and hydrogen must be present in order that a body be organic. Nevertheless, CO2 is the one exception allowed, and is classed among both organic and inorganic substances. 13. PROTOPLASM Living material is called protoplasm, and protoplasm is char- acterized by: - 1. Its power of movement (seen in amoeboid movement, cili- ary movement, muscular movement). 2. Its power of assimilation; that is, it is able to convert into protoplasm the nutrient material or food which is ingested. 3. Its power of growth - this is a natural consequence of its power of assimilation. 4. Its power of reproduction - this is a variety of growth. 5. Its power to excrete, to give out waste materials, the prod- ucts of its other activities. So far as we at present know, proteid material is never absent from living substances, and is never present in anything else than that which is alive or has been formed by the agency of living cells. The chemical structure of protoplasm can only be investigated after the protoplasm has been killed. The sub- stances it yields are: - 1. Water; protoplasm is semi-fluid, and at least three- quarters of this weight, often more, is due to water. 2. Proteids; these are the most constant and abundant of the solids. A proteid or albuminous substance consists of carbon, hydrogen, nitrogen, oxygen, with sulphur and phos- phorus in small quantity only. In nuclein (the proteid-like substance obtained from the nuclei of cells), phosphorus is more abundant. 3. Various other substances occur in smaller proportions, the most constant of which are lecithin, a phosphorized fat; cholesterin, a monatomic alcohol; and inorganic salts, especially phosphates and chlorides of calcium, sodium, and potassium. 14 ANATOMY FOR NURSES Living material is in a continual state of unstable chemical equilibrium, building itself up on the one hand, breaking down on the other. The sum total of these intermolecular rearrange- ments is metabolism. 14. THE CELL The cell is the fundamental form-element of every organized body (substance). It is one of the independent protoplasmic bodies which build up an animal (also a vegetable) fabric: as, bone-cells, cartilage-cells, muscle-cells, nerve-cells, fat-cells, etc. A typical cell is a mass of protoplasm, generally microscopic in size, containing a nucleus, and sometimes surrounded by a cell-wall (or cell-membrane). In the lower forms of life, and in most animal tissues, cells are often found without a cell-wall. 15. HEAT AS A FORM OF ENERGY. THE SOURCE OF EN- ERGY IN THE HUMAN BODY. THE MEASUREMENT OF HEAT AND ENERGY Heat and motion are different forms of energy (see paragraph 1). All the bodily activities are possible only by the expenditure of energy. Energy is transformable, that is, it may be changed from one form into another; for example, electricity may be changed into heat by which food may be cooked, or it may be changed into light, or it may be changed into working energy, whereby definite weights may be moved through space. In the human body heat and energy are evolved by the oxi- dation (see paragraph 5) of food. In the process of uniting with oxygen, these food-stuffs yield heat and energy for bodily warmth and activities. Heat may be measured and energy may be measured. The unit of measurement for each is the calorie. In measuring heat the calorie is the amount of heat required to raise one pound of water 4° F. or to raise one kilogram of water 1° C. In the measurement of energy the calorie is the amount of energy required to raise one ton through 1.53 feet of space. The number of calories required for heat and energy in the human body varies according to age, sex, occupation, and climate. Dietaries cannot be planned intelligently without the knowledge of the number of calories which should be supplied by the food of the individuals for whom the dietary is planned. CHAPTER I DEFINITIONS. -NAMES OF SURFACE PARTS. -GENERAL OUT- LINE OF THE BODY DEFINITIONS Before taking up the subjects of anatomy and physiology in detail, it is well first of all to consider the definitions of these terms as follows: - Anatomy refers to the structure of the body. Physiology refers to the functions of the different parts of the body. VERTEX SINCIPUT PALPEBRA SUPERIOR- OCULUS- PALPEBRA INFERIOR- TEMPOS OCCIPUT GENO-LABIAL SULCUS- PHILTRUM- OS MALA OR GENA MENTO-LABIAL SULCUS CERVIX OR COLLUM POMUM ADAMI Fig. 1. - Side view of cranium and face. (Gerrish.) Anatomy teaches us what organs a plant or animal has; physiology teaches us to what use these organs are put. Anat- omy shows what an organ is; physiology shows what an organ 15 Fig. 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. The right upper limb is drawn away from the trunk in order to show the arm more fully than is possible when it hangs perpendicularly. (Gerrish.) 16 OCCIPUT SHOULDER OMOS LOIN LUMBUS BUTTOCK NATIS OUTER ANKLE ,MALLEOLUS EXTERNU3 Fig. 3. - Back view of a man. On one lateral half the names of the parts are given in English, on the other in Latin. (Gerrish.) 17 18 ANATOMY FOR NURSES [Chap. I does. Anatomy may be and usually is studied upon the dead creature; physiology can be studied only upon the living creature. Anatomy is divided into the following branches: - Osteology is the anatomy of the bones. Syndesmology is the anatomy of the joints. Myology is the anatomy of the muscles. Angiology is the anatomy of the vessels. Neurology is the anatomy of the nerves. Splanchnology is the anatomy of the internal viscera.1 Adenology is the anatomy of the glands. Dermatology is the anatomy of the skin. Genesiology is the anatomy of the generative organs. NAMES OF SURFACE PARTS A general idea of the names and delimitations of surface parts is important, and a careful study of Figs. 1, 2, 3, and 4 will enable the student to understand many references made in the following pages. It is also necessary to have the clearest possible conception of the main di- visions and the positions of the different parts of the body, and we shall therefore begin our consideration of these subjects by outlining the structure of the body as a whole. The human body. - It is readily seen that the human body is separable into trunk, head, and limbs; the trunk and head are cavities, and AREOLA-^ MAMMILLA^ MAMMA VULVA^^d Fig. 4. - Front of torso of woman. (Gerrish.) 1 Viscera (viscus, an organ), organs contained within the body cavities. Example: heart, lungs, etc. Chap. I] CAVITIES OF THE BODY 19 contain the internal organs, or viscera, while the limbs are solid, contain no viscera, and are merely appendages of the trunk. CAVITIES OF THE BODY The trunk and head contain two mam cavities, and looking at the body from the outside we should naturally imagine that these two cavities were the cavity of the head and the cavity of the trunk, respec- tively. If, however, we divide the trunk and head lengthwise into two halves, by cutting them through the middle line from before backwards, we find the trunk and head are divided by the bones of the spine into back and front cavities, and not into upper and lower (vide dia- gram). 1. Dorsal cavity.-The dorsal or back cavity is a complete bony cavity, and is formed by the vertebrae (bones of the spine) and by the bones of the skull. It may be subdivided into: •-- a. The spinal canal, containing the spinal cord. b. The cranial cavity, containing the brain. 2. Ventral cavity. - The ventral or front cavity is not a complete bony cav- ity, part of its walls being formed of muscular and other tissue; it is much larger than the dorsal cavity, and may be subdivided into: - a. Thoracic cavity. - The thoracic cavity, or chest, containing the trachea or windpipe, the lungs, oesophagus or gul- let, heart, and the great vessels spring- ing from, and entering into, the heart. b. Abdominal cavity.-The abdomi- nal cavity, containing the stomach, liver, gall-bladder, pancreas, spleen, kidneys, small and large intestines, etc. Fig. 5.- Diagrammatic Longitudinal Section of the Trunk and Head. 1,1, the dorsal cavity; a, the spinal portion; b, the cra- nial enlargement; c, c, the bodies of the vertebras form- ing the partition between the dorsal and ventral cavi- ties ; 2, 2, the ventral cavity, subdivided into thoracic cavity (d), abdominal cavity (e), and pelvic cavity (/); g, the nasal cavity; h, the mouth, or buccal cavity. The alimentary canal {al) is represented running through the whole length of the ven- tral cavity. 20 ANATOMY FOR NURSES [Chap. I The diaphragm, a dome-shaped muscle, forms a transverse partition between the thoracic and abdominal cavities. c. Pelvic Cavity. - The pelvic cavity, containing the bladder. Fig. 6. - Position of the thoracic and abdominal organs (front view). (Morrow.) rectum, and in the female, the generative organs. It is that portion of the abdomen lying below an imaginary line drawn across the prominent crests of the hip bones. It is more com- pletely bounded by bony walls than the rest of the abdominal cavity. It is divided about its middle by an imaginary horizon- tal plane into a large (false) pelvis above, and a small (true) pelvis below. Buccal and nasal cavities. - Connected with the upper part of the ventral cavity are two small cavities, the buccal cavity, Chap. I] CAVITIES OF THE BODY 21 or mouth, containing the tongue, teeth, salivary glands, etc., and the nasal cavity, containing the organ of smell. The limbs, or extremities, upper and lower, are in pairs, and Fig. 7. - Position of the thoracic and abdominal organs (rear view). (Morrow.) bear a rough resemblance to one another, the shape of the bones, and the disposition of the muscles in the thigh and arm, leg and forearm, ankle and wrist, foot and hand, being very similar. There is, however, a marked difference between the mobility of the upper and the lower limbs. The shoulder is freely movable, not so the hip. 22 ANATOMY FOR NURSES [Chap.. I SUMMARY Dorsal cavity Spinal canal - Spinal cord. Cranial cavity - Brain. Tongue. Teeth. Salivary glands. Buccal cavity Nasal cavity Nose. HUMAN BODY Ventral cavity Thoracic cavity (Esophagus - Trachea. Lungs - Heart. Blood-vessels. Abdominal cavity Stomach - Spleen - Pancreas. Liver - Gall bladder. Kidneys - Large and small intestines. Pelvic cavity Bladder - Rectum. Generative organs (female). CHAPTER II STRUCTURAL UNITS OF THE BODY: CELLS, TISSUES, ORGAN, SYSTEM. EPITHELIAL TISSUE: STRATIFIED, TRANSITIONAL, SIMPLE STRUCTURAL UNITS OF THE BODY When any part of the body is separated by the aid of the microscope into its simplest parts, such parts are called its structural units. The structural unit of every part of the body is the cell. All the varied activities of the body are the result of the activity of the cells which .compose it, and it is very de- sirable that we early acquire some definite conception of these tiny elementary bodies. A CELL A cell is a minute portion of living substance (protoplasm, refer to preliminary chapter, para- graph 13) which is sometimes enclosed in a membrane (cell membrane or cell wall). It consists of a semi-fluid, often granular, part (cytoplasm, a form of protoplasm) surrounding a more solid part (the nucleus). In some cells no nucleus can be found. It may be assumed as true that at some period of its life every cell had a nucleus, though it may have been lost in the course of development. In the interior of the nucleus a still smaller body can be detected, known as the nucleolus. Nucleus. -The nucleus differs somewhat from the cytoplasm in function and in chemical composition. It is directly con- cerned in the nutrition and in the reproduction or division of Fig. 8. - Diagram of a Cell, n, nucleus; c, cyto- plasm. 23 24 ANATOMY FOR NURSES [Chap. II the cells. In dividing, the nucleus passes through a series of remarkable changes, which are too complicated to be studied here. (See Fig. 9.) The result of these changes is that either directly or indirectly the nucleus splits into two, and the pro- toplasm divides and arranges itself around the new nuclei; these daughter cells soon grow to the size of the parent cell, and division of these and con- sequent multiplication may proceed with great rapidity. (For cell nutrition, refer to preliminary chapter.) During the life of a cell its protoplasm is constantly un- dergoing changes, the chief of which may be enumerated as follows: - (1) Oxidation.-All proto- plasm coming in contact with oxygen absorbs it and com- bines with it. Whenever this combination takes place, a cer- tain amount of the protoplasm is burned or oxidized, and as a result of this oxidation heat and other kinds of energy are produced, and carbon dioxide evolved. (2) Metabolism. - All proto- plasm is able to take to itself, and eventually convert into its own substance, certain materials (foods) that are non-living; in this way the protoplasm may increase in amount, or in other words, the cell may grow. The amount of protoplasm is not permanently increased, because just as much protoplasm is being broken down by the process of oxidation, and removed from the cell, as is added by the process of assimilation. Chemical changes which involve the building up of living material within the cell have received the Fig. 9. -A to H, Consecutive Stages of Cell-Di vis ion, with Indirect Divi- sion of the Nucleus. (Diagrammatic.) Chap. II] ORGAN 25 general name of anabolic changes, or anabolism; on the other hand, those which involve the breaking down of such material into other and simpler products, are known as katabolic changes, or katabolism, while the sum of all the ana- and katabolic changes which are proceeding within the cell are spoken of as the metabolism of a cell. These chemical changes are always more marked as the activity of the cell is promoted by warmth, electrical, or other stimulation, the action of certain drugs, etc. (3) Amoeboid movement. - The most obvious physical changes that can sometimes be seen in living protoplasm, by the aid of the microscope, are those which are termed " amoeboid." This term is derived from the amoeba, a single-celled organism which has long been observed to exhibit spontaneous changes of form, accompanied by a flowing of its soft semi-fluid substance. By virtue of this property, the cells can move from one place to another. If one of these cells be observed under a high-power lens of the microscope, it will be seen gradually to protrude a portion of its protoplasm; this protrusion extends itself, and the main part or body of the cell passes by degrees into the elongated protrusion. By a repetition of this process, the cell may glide slowly away from its original situation and move bodily along the field of the microscope, so that an actual loco- motion takes place. When the surface of these free cells comes in contact with any foreign particles, the protoplasm, by virtue of its amoeboid movements, tends to flow round and enwrap the particles, and particles thus enwrapped or incepted may then be conveyed by the cell from one place to another. TISSUE A collection of cells of like substance arranged together form what is known as a tissue. ORGAN When one or more different tissues are associated in per- forming some special office in the body, the part so adapted is termed an organ. Thus, the lungs are organs specially adapted for assisting in the function of respiration, the bones are organs adapted for support and locomotion, the kidneys for secreting urine, etc. As the structure of an organ depends upon the 26 ANATOMY FOR NURSES [Chap. II properties of the tissues composing it, so the characteristics of each tissue depend upon their ultimate structural units - the cells and the intercellular substance. SYSTEM OR APPARATUS An arrangement of organs closely allied to each other and set apart to perform some general function is spoken of as a system, or apparatus. Example: muscular system or respiratory apparatus. CLASSIFICATION By the aid of the microscope the different distinct tissues of which the body is formed are found to be comparatively few in number, and some of these, again, although at first sight ap- parently distinct, yet have so much in common in their struc- ture and origin one with another, that the number becomes still further reduced, until we can only distinguish four distinct tissues, viz.: - 1. The epithelial tissues. 3. The muscular tissues. 2. The connective tissues. 4. The nervous tissues. Such fluids as blood and lymph are included among the tissues, and are frequently described as liquid tissues. Some organs are formed of a combination of several of the above tissues; others contain only one or two. Thus the muscles are made up almost entirely of muscular tissue, with only a small intermixture of connective tissue, blood-vessels, and nerves; whilst the ligaments or sinews are composed wholly of a variety of connective tissue. Origin of tissues. - The early embryo is an agglomeration of cells, and the whole of the body is developed out of one cell, called the ovum, which measures about jJ-g- of an inch (0.2 mm.1) 1 On page 385 will be found accurate ratios' between the metric system and the system of length, weights, and measures used in the United States. For the sake of simplicity in converting figures in the text, from one system to the other, we have assumed 1 cm. to equal f in. (25 mm. = 1 in.). 1 cc. to equal 15 minims. 30 gm. to equal 1 oz. (dry or liquid measure). 30 cc. to equal 1 oz. (dry or liquid measure). 1 litre to equal 1.75 pt. (dry measure). 1 litre to equal 2.11 pt. (liquid measure). Chap. II] EPITHELIAL TISSUE 27 in diameter. In the beginning of the formation of the body, the protoplasm of the ovum divides and subdivides, and the daughter cells thus formed eventually arrange themselves in the form of a membrane (blastoderm), which is composed of three layers. These layers are known respectively as ectoderm, me- soderm, and entoderm. The ectoderm gives rise to the nervous tissue and most of the epithelial; the mesoderm to the connec- tive and muscular tissues; the entoderm 'to the epithelium of the alimentary canal (except the mouth) and the glands in connec- tion with it. Of these tissues, the epithelial is the simplest and most nearly allied to the primitive tissue, and will first engage our attention. EPITHELIAL TISSUE Epithelial tissue is composed entirely of cells united together by adhesive matter or cement substance. The cells are generally so arranged as to form a skin, or membrane, covering the external surfaces, and lining the internal parts of the body. This mem- brane is seen when the skin is blistered, the thin and nearly transparent membrane raised from the surface being epithelial tissue - in this situation called epidermis, because it lies upon the surface of the true skin. In other situations, epithelial tissue usually receives the general name of epithelium. Some varieties of epithelium are specially modified to form protective membranes; others to elaborate or make secretions; others, again, to form smooth linings for opposing surfaces; others to keep surfaces moist; and yet others to keep the surfaces they cover clean by sweeping outwards material that would otherwise accumulate and clog important passages. We may classify the varieties of epithelium according to the shape of the cells which compose them, or according to the arrangement of these cells in layers. Adopting the latter and simpler classification, we distinguish three main varieties: - 1. The stratified, consisting of many layers. 2. The transitional, consisting of two or three layers. 3. The simple, consisting of a single layer of cells. 1. Stratified epithelium. - The cells composing the different layers of stratified epithelium differ in shape. As a rule, the 28 ANATOMY FOR NURSES [Chap. II cells of the deepest layer are columnar in shape; the next, rounded or many-sided, whilst those nearest the surface are always flattened and scale-like, the protoplasm of the cells being finally converted into a horn-like substance. The deeper soft Fig. 10. - Section of Stratified Epithelium, c, lowermost columnar cells; P, polygonal cells above these; fl, flattened cells near the surface. Between the cells are seen intercellular channels, bridged over by processes which pass from cell to cell. (Schafer.) cells of a stratified epithelium are separated from one another by a system of channels, which are bridged across by numerous fibres. These cells are often described as prickle cells, as when separated they appear beset with spines. They are continually multiplying by cell-division, and as the new cells which are thus produced in the deeper parts increase in size, they compress and push outwards those previously formed. In this way cells which were at first deeply seated are gradually shifted outwards and upwards, growing harder as they approach the surface. The older superficial cells are being continually rubbed off as the new ones continually rise up to supply their places. Stratified epithelium covers the anterior surface of the eye, lines the mouth, the chief part of the pharynx, the gullet, the anal canal, part of the urethra, and in the female the vagina and neck of the uterus. Its most extensive distribution is over the surface of the skin, where it forms the epidermis. Whenever a surface is exposed to friction, we find stratified scaly epithelium, and we may there- fore classify it as a protective epithelium. 2. Transitional epithelium. - This is a modification of strati- fied epithelium, consisting only of two or three layers of cells. The superficial cells are large and flattened, having on their under surface depressions into which fit the larger ends of the pear-shaped cells which form the next layer. Between the Chap. II] EPITHELIAL TISSUE 29 tapering ends of these pear-shaped cells are one or two layers of smaller, many-sided cells, the epithelium being renewed by Fig. 11. - Section of the Transitional Epithelium lining the Bladder. (Highly magnified.) a, superficial; b, intermediate; c, deep layer of cells. (Schafer.) division of these deeper cells. This kind of epithelium lines the bladder and ureters. 3. Simple epithelium. - This is composed of a single layer of cells. The cells forming single layers are of distinctive shape, and have distinctive functions in different parts of the body. The chief varieties are: - a. pavement.1 b. columnar. c. glandular. d. ciliated. (a) Pavement epithelium. - In pavement epithelium the cells form flat, many-sided plates or scales, which fit together like the tiles of a mo- saic pavement. It forms very smooth surfaces, and lines the heart, blood-vessels, and lymphatics, the mammary ducts, the serous cavities, etc. When occurring on internal surfaces such as the serous mem- branes, blood-vessels, and lymphatics, it is called endothelium,2 and is derived from the entoderm and not the ectoderm. (6) Columnar epithelium. - The columnar epithelium is a va- riety of simple epithelium in which the cells have a prismatic shape, and are set upright on the surface which they cover. In Fig. 12. - Simple Pave- ment Epithelium. a, from a serous membrane; b, from a blood-vessel. 1 Pavement epithelium is also described as simple scaly epithelium. 2 Endothelium lines closed passages that have no external opening. 30 ANATOMY FOR NURSES [Chap. II profile these cells look somewhat like a close palisade. They taper somewhat toward their attached end, which is set upon a basement membrane. Columnar epithelium is found in its tnost characteristic form lin- ing the mucous membrane 1 of the intesti- nal canal. (c) Glandular epithelium. - This variety of epithelium is found in the recesses of secret- ing glands. The cells are of many different shapes, and are usually set round a tubular or saccular cavity, into which the secretion is poured. The proto- plasm of these cells is generally filled by the materials which the gland secretes. (d) Ciliated epithelium. - In ciliated epithelium the cells, which are generally columnar in shape, bear at their free surface little hair-like processes (strongly suggestive of eye- lashes), which are agitated incessantly with a lashing or vibrating motion. These minute and delicate pro- cesses are named cilia, and may be regarded as active prolongations of the cell- protoplasm. The manner in .which cilia move is best seen when they are not acting very quickly. The motion of an individual cilium may be compared to the lash-like motion of a short-handled whip, the cilium being rapidly bent in one direction. The motion Fig. 13.-Simple Col- umnar Epithelium, a, the cells ; b, intercellular substance between the lower end of cells. Fig. 14. - Glandular Epithelium, with the Cells set round a Simple Saccular Gland. (Highly magnified.) (Flemming.) Fig. 15. - Ciliated Epithelium from the Human Trachea. (Highly magnified.) a, large ciliated cell; d, cell with two nuclei. 1 Mucous membrane lines passages that communicate with the exterior, and are moistened by mucus. Chap. II] SUMMARY 31 does not involve the whole of the ciliated surface at the same moment, but is performed by the cilia in regular succession, giving rise to the appearance of a series of waves travelling along the surface like the waves tossed by the wind in a field of wheat. When they are in very rapid action, their motion con- veys the idea of swiftly running water. As they all move in one direction, a current of much power is produced. Cilia have been shown to exist in almost every class of animal, from the highest to the lowest. In man their use is to impel secreted fluids, or other matters, along the surfaces to which they are attached; as, for example, the mucus of the trachea and nasal chambers, which they carry towards the outlet of these passages. Ciliated epithelium is found in the air-passages, in parts of the generative organs, ventricles 1 of the brain, and central canal of the spinal cord. The hairs, nails, and the enamel of the teeth are modifications of epithelial tissue. SUMMARY Structural unit of the body is a cell. "Cell membrane - may or may not be present. Cytoplasm - a form of protoplasm. Nucleus - a more solid central portion. Nucleolus -a smaller body in interior of nucleus. Cells . . . "Oxidation. Metabolism. Amoeboid movements. Cell Changes The cell assimilates, is continually building itself up and replenishing its store of energy, is as continually breaking down into simpler products with a setting free of energy; it grows; it moves; it reproduces itself - in other words, it is alive and is the basis of all life. Tissues are made up of a collection of cells. Organs are made up of tissues. System - a group of organs set apart to perform some special function. Four Distinct Tissues .... 1. Epithelial. 2. Connective. 3. Muscular. 4. Nervous. 'Ectoderm. Mesoderm. . Entoderm. Ovum Embryo - Blastoderm 1 The function of ciliated epithelium as found in the ventricles of the brain and spinal cord is unknown. 32 ANATOMY FOR NURSES [Chap. II Epithelial - a tissue of cells and little intercellular substance. Stratified, consisting of many layers. Transitional, consisting of 2 or 3 layers. Classification of Epithelial Tissue Pavement or scaly. Columnar. Glandular. Ciliated. Simple, consisting of a single layer. The most important situations in which a covering or lining of epithelial tissue is found in the body are : - 1. On the surface of the integument, or external skin. 2. On mucous membranes, or internal skin; and in the recesses of secreting glands. 3. On the inner surface of serous membranes, and on the inner surface of the heart, blood-vessels, and lymphatics. 4. Lining the ventricles or cavities of the brain, and the central canal of the spinal cord. 5. Epithelial cells, variously modified, are also found in the sensory terminations of the organs of special sense. CHAPTER III CONNECTIVE TISSUES: AREOLAR, FIBROUS, ELASTIC, ADI- POSE, RETICULAR, LYMPHOID, CARTILAGE, BONE Following the classification of tissues we have adopted, the next group of tissues to be studied is that known as the con- nective tissue group. When connective tissue first begins to be formed as a dis- tinctive tissue, the cells which are set apart to form it are round in shape and loosely packed together; later, these cells begin to throw out branches and to form a kind of network with open spaces. In these open spaces a semi-fluid substance is deposited, which gradually becomes more consistent, and in this substance is developed the particular fibres which are the chief structural characteristics of connective tissue. Our description of epithelial tissue was briefly this: a skin or membrane formed of cells, which cells may be of a variety of shapes, and be arranged in one or more layers. It is distinctly a tissue of cells with very little of what we call intermediate or intercellular substance lying between the cells. Connective tissue differs from epithelial tissue in having a great deal of intercellular substance between its cells, and according to the manner in which this intercellular substance develops do we get the different varieties of connective tissue. CONNECTIVE TISSUE GROUP These tissues differ considerably in their external characteristics, but are alike in that they all serve to connect and support the other tissues of the body; there are many points of similarity between the cells which occur in them, and we may, therefore, reasonably group them together, as follows: - 33 34 ANATOMY FOR NURSES [Chap. Ill 1. Areolar tissue. 2. Fibrous tissue. 3. Elastic tissue. 4. Adipose tissue. 5. Reticular tissue. 6. Lymphoid tissue. 7. Cartilage. 8. Bone or osseous tissue. Areolar tissue. - This tissue appears to be composed of a multitude of fine threads or films, called fibres. Viewed with a microscope, these fibres are seen to be principally made up of wavy bundles of exquisitely fine, transparent, white fibres, and these bundles intersect in all directions. Mixed with the white fibres are a certain number of elastic fibres, which do not form bundles, and have a straight instead of a wavy outline. Between Fig. 16. - Subcutaneous Areolar Tissue from a Young Rabbit. (Highly magnified.) The white fibres are in wavy bundles, the elastic fibres form an open network, p, p, vacuolated cells; g, granular cell; c, c, branching lamellar cells; c', a flattened cell, of which only the nucleus and some scattered granules are visible; f, fibrillated cell. (Schafer.) these fibres are open spaces, called areolte,1 that communicate freely with one another. Lying in the areolse between the bundles of fibres are seen the tissue-cells, of which there are many varieties. 1 Areola is the Latin word for "a small space." Areolar tissue gets its name from appearing full of minute spaces. Chap. Ill] FIBROUS TISSUE 35 If we make a cut through the skin of some part of the body where there is no subcutaneous fat, as in the upper eyelid, and proceed to raise it from the parts lying beneath, we observe that it is loosely connected to them by a soft, filmy substance of con- siderable tenacity and elasticity. This is areolar tissue. It is also found, in like manner, under the serous and mucous mem- branes, and serves to attach them to the parts which they line or cover. Proceeding further, we find this areolar tissue lying between the muscles, the blood-vessels, and other deep-seated parts; also forming investing sheaths for the muscles, the nerves, the blood-vessels, and other parts. It both connects and in- sulates entire organs, and, in addition, performs the same office for the finer parts of which these organs are made up. It is thus one of the most general and most extensively distributed of the tissues. It is, moreover, continuous throughout the body, and from one region it may be traced without interruption into any other, however distant, - a fact not without interest in practical medicine, seeing that in this way air, water, and other fluids, effused into the areolar tis- sue, may spread far from the spot where they were first introduced or deposited. On comparing the areolar tissue of different parts, it is observed in some to be more loose and open in texture; in others, more close and dense, according as free movement or firm connection between parts is to be provided for. Fibrous tissue. - This tissue is intimately allied in . structure to the areolar tissue. It consists al- most wholly of white fibres, which cohere very closely and are ar- ranged side by side in bundles which have an undulating outline. The spaces between the bundles are occupied by cells arranged in rows, but the cells are not a prominent feature of this tissue. The fibres may be Fig. 17. - Fibrous Tissue, from the Longitudinal Section of a Tendon. The spaces between the bundles of fibres are occupied by rows of cells. (Gegenbauer.) 36 ANATOMY FOR NURSES [Chap. Ill some inches long, do not branch, and confer a distinctly fibrous aspect on the parts which they compose. Fibrous tissue is white, with a peculiarly shining, silvery aspect. It is exceedingly strong and tough, yet perfectly pliant; but it is almost devoid of extensibility. By these qualities it is ad- mirably suited to the purposes for which it is used in the human frame. It is met with in the form of: - (1) Ligaments, connecting the bones together at the joints. (2) Tendons, or sinews, which serve to attach the muscles to the bones. (3) Fascia (a bandage), employed to envelop and bind down the larger muscles. (4) Aponeuroses, serving to connect one muscle to another. (5) Protecting sheaths, or membranes, investing and protecting different organs of the body. It thus appears that fibrous tissue presents itself in the form of strong bands or cords, and of dense sheets or membranes. By its inextensile character and by its strength it maintains in apposition the parts which it connects, and we find that the ligaments and tendons do not sensibly yield to extension in the strongest muscular efforts; and though they sometimes snap assunder, it is well known that bones will break more readily than ligaments; and the fibrous membranes, or aponeuroses, are equally strong, tough, and unyielding. Elastic tissue. - In elastic tissue the wavy white bundles are comparatively few and indistinct, and there is a propor- tionate development of the elastic fibres. When present in large numbers, they give a yellowish colour to the tissue. This form of connective tissue is extensile and elastic in the highest degree, and wherever located, does such work as India rubber would do. It is not so strong as the fibrous variety, and breaks across the direction of its fibres when forcibly stretched. This tissue is found chiefly: - (1) Between the bones of the spine in elastic bands. (Liga- menta flava.) (2) In the walls of the blood-vessels (especially arteries), air- tubes, and vocal folds. (3) Entering into the formation of the lungs and uniting the cartilages of the larynx. Chap. Ill] ADIPOSE TISSUE 37 These three varieties of connective tissue (areolar, fibrous, elastic) agree closely with one another in elementary structure. It is the different arrangement of the cells and fibres, and the relative proportion of one kind of fibre to the other, that gives them their different characteristics: the interlacing of the wavy bundles of finest fibres, giving us the delicate web-like areolar tissue; the close packing of these bundles giving us the dense, opaque, fibrous membranes and bands, and the preponderance of the elastic fibres furnishing the extensile elastic tissue. They are used for purely mechanical purposes: forming inextensile bands or pulleys; strong protective membranes; web-like, binding, and supporting material; sheaths of varying degrees of density; elastic bands or membranes; and they also serve to carry the blood-vessels, lymphatics, and nerves to the parts which they connect and cover. Adipose tissue. - When fat first begins to be formed in the embryo, it is deposited in tiny droplets in some of the cells of Fig. 18. - A Few Fat Cells from the Margin of a Fat Lobule. (Very highly magnified.) f.g. fat globules distending a fat cell; n, nucleus; m, membra- nous envelope of the fat cell; c, capillary vessel; v, veinlet; c.t. connective-tissue cell; the fibres of the connective tissue are not shown. (Schafer.) the areolar connective tissue; these droplets increase in size, and eventually run together so as to form one large drop in each cell. By further deposition of fat the cell becomes swollen out to a size far beyond that which it possessed originally, until 38 ANATOMY FOR NURSES [chap. Ill the protoplasm remains as a delicate envelope surrounding the fat drop. The nucleus is crowded off to one side and attached to the cell wall. As these cells increase in number they collect into small groups or lobules, which lobules are for the most part lodged in the meshes of the areolar tissue, and are also supported by a fine network of blood-vessels. This fatty tissue exists very generaTy throughout the body, accompanying the still more widely distributed areolar tissue in most parts, though not in all, in which the latter is found. Still, its distribution is not uniform, and there are some situations in which it is collected more abundantly. This tissue is found chiefly: - (1) Underneath the skin, in the subcutaneous layer. (2) Beneath the serous membranes or in their folds.1 (3) Collected in large quantities around certain internal organs, especially the kidneys. (4) Filling up furrows on the surface of the heart. (5) As padding around the joints. (6) In large quantities in the marrow of the long bones. Adipose .tissue, unless formed in abnormal quantities, confers graceful outlines upon the human frame. It constitutes an important reserve fund, by storing up fatty materials, derived from the food and brought to it by the blood, in such a form and manner as to be readily reabsorbed into the circulation when needed. It also serves as a covering or jacket for the con- servation of body heat. Reticular tissue, or retiform.2 - This variety of connective tissue consists of a close network of white fibres with few, if any, yellow fibres. The meshes of the network are small and close in some parts, more open and like areolar tissue in other parts. The fibres are nearly covered by fibrous tissue cells in the form of broad, thin plates wrapped around them. It forms a fine framework in many organs. Lymphoid tissue, or adenoid.3 - This is reticular tissue in 1 Always found in the great serous apron (omentum) which hangs down in front of the bowels. 2 Reticulum is the diminutive of the Latin rete, "a net," and consequently means " a little net." 3 "Adenoid" comes from the Greek word for "gland," and signifies "gland-like." Chap, III] CARTILAGE 39 Fig. 19. - Retiform Tissue from a Lymph Node, r, r, r, represent open meshes of this tissue. (Quain.) which the meshes of the network are occupied by lymph cor- puscles. This is the most common condition of retiform tissue, and is met with in lymph nodes and similar structures. Cartilage. - This is the well- known substance called "gristle." Although cartilage can be readily cut with a sharp knife, it is nevertheless of very firm consistence, but at the same time highly elastic, so that it readily yields to extension or pressure, and immediately re- covers its original shape when the constraining force is with- drawn. When a very thin sec- tion is examined with a micro- scope, it is seen to consist of nucleated cells disposed in small groups in a mass of intercellular substance. This intercellular substance is sometimes trans- parent, and to all appearances structureless; sometimes it is pervaded with white fibres and sometimes with yellow fibres. According to the amount and texture of the intercellular sub- stance, we distinguish three principal varieties: - ' .1111:'! '="" T. BENA UDO T E. SALLE Fig. 20. - Articular Hyaline Cartilage from the Femur of an Ox. s, intercellular substance; p, protoplasmic cell; n, nucleus. (Ran- vier.) 40 ANATOMY FOR NURSES [Chap. Ill (1) Hyaline or true cartilage. (2) White fibro-cartilage. (3) Yellow or elastic fibro-cartilage. Hyaline cartilage. - This variety is named from the Greek word for glass. A comparatively small number of cells are em- bedded in an abundant quantity of intercellular substance which has the appearance of ground glass. The most typical form of this tissue occurs principally in two situations; viz.: - 1. Covering the ends of the bones in the joints, where it is known as articular cartilage. 2. Forming the rib cartilages, where it is known as costal cartilage. In both these situations the cartilages are in immediate con- nection with bone, and may be said to form part of the skele- ton, hence frequently described as skeletal cartilages. The articular cartilages, in covering the ends or surfaces of bones in the joints, provide these harder parts with a thick, springy coating, which breaks the force of concussion, and gives ease to the motion of the joint. The costal cartilages, in form- ing part of the solid framework of the thorax or chest, impart elasticity to its walls. Hyaline cartilage also enters into the formation of the nose, ear, larynx, and windpipe. It strengthens the substance of these parts without making them unduly rigid, maintains their shape, keeps open the passages through them where such exist, and gives attachment to moving muscles and connecting ligaments. White fibro-cartilage. - The intercellular substance is per- vaded with bundles of white fibres, between which are scattered cartilage cells. It closely resembles white fibrous tissue, and is found wherever great strength, combined with a certain amount of rigidity, is required; thus we find it joining bones together, the most familiar instance being the flat, round plates or disks of fibro-cartilage connecting the bones of the spine and the pubic bones. In these cases the part in contact with the bone is always hyaline cartilage, which passes gradually into the fibro- cartilage. Yellow, or elastic, fibro-cartilage. - The intercellular substance is pervaded with yellow elastic fibres which form a network. Chap. Ill] BONE, OR OSSEOUS TISSUE 41 In the meshes of the network the cartilage cells are found. It occurs only in parts of the throat and ear.1 Cartilage is not supplied with nerves, and very rarely with blood-vessels. Being so meagrely supplied with blood, the vital processes in cartilage are very slow, and when a portion of it is absorbed in disease or removed by the knife, it is regenerated very slowly. A wound in cartilage is usually at first healed by connective tissue proper, which may or may not become grad- ually transformed into cartilage. Nearly all cartilages receive their nourishment from the perichondrium which covers them, and which is a moderately vascular fibrous membrane. Bone, or osseous tissue. - Bone is connective tissue in which the intercellular or ground substance is rendered hard by being impregnated with mineral salts. The mineral, or earthy, substance which is deposited in bone, and which makes it hard, amounts to about two-thirds of the weight of the bone. It consists chiefly of phosphate of calcium, with about a fifth part of carbonate of calcium., and a small portion of other salts. The organic, or soft, matter consists chiefly of blood-vessels and connective tissue, and may be resolved by boiling almost entirely into gelatine: it constitutes about one-third of the weight of the bone.2 On sawing up a bone it will be seen that it is in some parts dense and close in texture, appearing like ivory, whilst in others 1 Found in the epiglottis, cartilages of the larynx, Eustachian tube, and external ear. 2 It is possible to separate each of these substances. The mineral matter may be removed by soaking a bone in dilure acid for several days. The result will be a tough, flexible, elastic substance, consisting only of organic matter. The shape of the bone will be preserved, but the specimen will be so free from stiffness that it may be tied in a knot. The organic matter may be driven off by heat. As before, the shape of the bone will be preserved. The specimen will consist only of mineral matter, will appear white, rigid, and so brittle it can be crushed between the fingers. In the disease called rachitis, quite common among poorly nourished children, there is not sufficient mineral matter, so that the bones are flexible, bend easily, and may be permanently misshapen. Organic matter predominates in early life, and this accounts for so-called "Green-stick fractures." The bone bends like a bough of green wood. Some of the fibres may break, but not the whole bone. 42 ANATOMY FOR NURSES [Chap. Ill it is open and spongy, and we thus distinguish two forms of bony tissue: - (1) The dense, or compact. (2) The spongy, or cancellated. On closer examination, however, it will be seen that the bony matter is everywhere porous, and that the difference between the two varieties of tissue arises from the fact that the compact tissue has fewer spaces and more solid matter between them, while the cancellated has larger cavities and more slender intervening bony partitions. In all bones the compact tissue is the stronger; it lies on the surface of the bone and forms an outer shell or crust, whilst the lighter spongy tissue is contained within. The shafts of the long bones are almost en- tirely made up of the compact substance, except that they are hollowed out to form a central canal, - the medullary canal, - which has a fibrous lining called endosteum, and contains marrow.1 Marrow is also found in the spongy portions of the bone in the spaces between the bony partitions. The hard substance of both varieties is arranged in bundles of bony fibres, or lamellae (layers). Cancellated bone. - In cancellated bone the lamellae join and meet together so as to form a structure resembling lattice-work (cancelli), whence this tissue receives its name. In the interstices of this kind of bone we find the blood-vessels supported by the marrow. /(CANCELLOUS / SUBSTANCE. Fig. 21.--Vertical Section of a Long Bone. (Gerrish.) 1 There are two kinds of marrow, red and yellow. Red marrow contains, in 100 parts, 75 of water and 25 of solids, the solids consisting of albumin, fibrin, extractive matter, salts, and a mere trace of fat. Yellow marrow contains, in 100 parts, 96 of fat, 1 of areolar tissue and vessels, and 3 of fluid. FIBROUS layer of periosteum OSTEOGENETiC CELLS LAMELLAE LACUNAE 7 COMPLETE ~ HAVERSIAN ' SYSTEM CANALICULI HAVERSIAN CANAL Fig. 22. - Diagram of the Structure of Osseous Tissue. A small part of a transverse section of the shaft of a long bone is shown. At the uppermost part is the periosteum covering the outside of the bone; at the lowermost 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 lamellae; 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 lacunae are in all parts. The periosteum is seen to lie 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. (Gerrish.) 43 44 ANATOMY FOR NURSES [Chap. HI Compact bone. - In compact bone the lamellae are usually arranged in rings around canals, - Haversian canals, - which carry blood-vessels in a longitudinal direction through the bones. Between the lamellae are branched cells which lie in cell-spaces, or cavities, called lacunae (little lakes), and running out in a wheel-like or radial direction from each lacuna are numerous tiny wavy canals called canaliculi, connecting one lacuna with another, and forming a system of minute channels which communicate with each other and with the Haversian canal. This constitutes an Haversian System, so named from Havers, a celebrated anatomist. Many such systems may be found in the shaft of a long bone. The spaces between these systems are filled by lamellae arranged at irregular angles. Periosteum. -All bones are covered, except at the joints, by a vascular fibrous membrane, the periosteum (around the bone). It consists of an outer fibrous layer and an inner vascular layer. The attachment of the periosteum to bone is rendered firmer by inward prolongations of the fibrous layer called the fibres of Sharpey. Unlike cartilage, the bones are plentifully supplied with blood. If we strip the periosteum from a fresh bone, we see many bleed- ing points representing the canals (Volkman's) through which the blood-vessels enter and where they leave the bone. These blood- vessels proceed from the periosteum to join the system of Haver- sian canals. Around the Haversian canals the lamellae are dis- posed, while lying between them, arranged in circles, are found the lacunae, which contain the bone-cells. Running from one lacuna to another in a radial direction through the lamellae towards the centre are the canaliculi. Following this scheme, it will be seen that the innermost canaliculi run into the Ha- versian canals, and thus is established a direct communication between the blood in these canals and the cells in the lacunae connected with and surrounding each Haversian canal. In this way the whole substance of the bone is penetrated by inter- communicating channels, and the nutrient matters and mineral salts from the blood in the Haversian canals can find their way to every part. Function of periosteum in growth of bone. - In the embryo the foundation of the skeleton is laid in cartilage, or in primitive Chap. Ill] SUMMARY 45 membranous connective tissue, ossification of the bones occur- ring later. The hardening or ossification of the bones is accom- plished by the penetration of blood-vessels and bone-cells, called osteoblasts, from the periosteum. As they penetrate into the cartilaginous or membranous models, they absorb the cartilage and connective tissue and deposit the true bone tissue at various points until they form the particular bony structure with which we are familiar. Regeneration of bone. - In the reunion of fractured bones new bony tissue is formed between and around the broken ends, connecting them firmly together; and when a portion of bone dies, a growth of new bone very generally takes place to a greater or less extent, and the dead part is thrown off. The periosteum is largely concerned in this process of repair; for if a portion of the periosteum be stripped off, the subjacent bone will be liable to die, while if a large part or the whole of a bone be removed, and the periosteum at the same time left intact, the bone will wholly or in a great measure be regenerated. SUMMARY CONNECTIVE TISSUE - A tissue of cells with a great deal of inter- cellular substance. Areolar, Fibrous, Elastic, „ Adipose, Reticular, Lymphoid, Cartilage, Bone. CLASSIFICATION . Areolar - Formed by interlacing of wavy bundles of white fibres and some straight elastic fibres with cells lying in the spaces. Connects, insulates, forms protecting sheaths, and is continuous throughout whole body. Fibrous - Formed of wavy bundles of white fibres only, with cells in rows between bundles. Very strong and tough but pliant. Found in form of ligaments, sinews, tendons, fascise, aponeuroses, and protecting sheaths. Elastic - Formed of yellow elastic fibres with few bundles of white fibres. Extensile, elastic, serves same purpose as India rubber. Found in liga- menta flava, blood-vessels, air-tubes, vocal folds, lungs, and larynx. Adipose - Modification of areolar tissue, with cells enlarged and filled with fat. Distribution quite general but not uniform. Confers graceful out- lines, stores up fatty materials, and conserves heat. Reticular - Network of white fibres with few yellow fibres. Cells wrapped around fibres. Forms a supporting framework in many organs. 46 ANATOMY FOR NURSES [Chap. Ill Lymphoid - Reticular tissue with meshes of network occupied by lymph corpuscles. Found in lym^h nodes. Cartilage - or gristle is a bluish white tissue, firm and elastic, covered and nourished by perichondrium. Varieties 1. Hyaline or true Articular Costal Skeletal. 2. White fibro. .3. Yellow fibro. Hyaline - Small number of cells in an abundant quantity of intercellular substance. Found as articular cartilage, covering ends of bones in joints. Found as costal cartilage, connecting ribs and sternum. White Fibro-Intercellular substance pervaded with white fibres. Re- sembles fibrous tissue. Found between spinal and pubic bones. Yellow Fibro- Intercellular substance pervaded with network of yellow elastic fibres. Found in parts of throat and ear. Mineral matter 2 3 ' Phosphate of calcium. Carbonate of calcium. Small portion of other salts. Organic matter i ■3 Blood-vessels. Connective tissue. Marrow. BONES OR OSSEOUS TISSUE Varieties ' Dense or compact like ivory. . Spongy or cancellated. Medullary Red Marrow. Yellow Marrow. Canals Haversian Blood-vessels. Lymphatics. 'Haversian canal. Lamellae - bony fibres arranged in rings around Haversian canal. Lacunae - small spaces between lamellae occupied by bone cells. Canaliculi - canals which radiate from lacunae to the Haver- _ sian canal. Haversian System Endosteum - A fibrous membrane that lines the marrow cavity. Periosteum - A vascular fibrous membrane that covers the bones. Im- portant in reunion of broken bone and growth of new bone. Fibres of Sharpey - Inward prolongations of periosteum. CHAPTER IV THE SKELETON The bones are the principal organs of support, and the passive instruments of locomotion. Connected together in the skeleton, they form a framework of hard material, affording at- tachment to the soft parts, maintaining them in their due posi- tion, sheltering such as are of delicate structure, giving stability to the whole fabric, and preserving its shape. The entire skeleton in the adult consists of two hundred dis- tinct bones. These are: - Cranium 8 Face 14 Hyoid 1 The spine, or vertebral column (sacrum and coccyx included) 26 Sternum and ribs .... 25 Upper extremities .... 64 Lower extremities .... 62 200 In this enumeration the patellae, or knee-pans, are included as separate bones, but the smaller sesamoid 1 bones and the small bones of the middle ear, namely, Malleus (2), Incus (2), and Stapes (2) are not included. CLASSIFICATION The bones may be divided according to their shape, into four classes: 1. Long, 2. Short, 3. Flat, and 4. Irregular. 1 The sesamoid (shaped like sesame seed) bones are several small bones which are found embedded in tendons covering the bones of the knee, hand, and foot. 47 48 ANATOMY FOR NURSES [Chap. IV The long and short bones are found in the extremities. The flat and irregular bones are found in the trunk and head, with the exception of the patellae, which are two small, flat bones found in FRONTAL- ORBIT- .PARIETAL TEMPORAL MAXILLA MANDIBLE -CERVICAL VERTEBRAE - FEMUR PATELLA I FIBULA Fig. 23.-The Human Skeleton. (Morrow.) the lower extremities, and the scapulae, which are also two flat bones usually reckoned among the bones of the upper extremities. The bones of the trunk and head are used chiefly to form cavities and to support and protect the organs contained in these cavities. The bones of the extremities enclose no cavities, and are chiefly used in the upper extremity for tact and prehension Chap. IV] THE SKELETON 49 and in the lower for support and locomotion; in both situations they form a system of levers. Long bones. - A long bone consists of a lengthened cylinder, or shaft, and two extremities. The shaft is formed mainly of compact tissue, this compact tissue being thickest in the middle, where the bone is most slender and the strain greatest, and it is hollowed out in the interior to form the medullary canal. The extremities are made up of' spongy tissue with only a thin coat- ing of compact substance, and are more or less expanded for greater convenience of mutual connection, and to afford a broad surface for muscular attachment. All long bones are more or less curved, which gives them greater strength and a more grace- ful outline. Example - Arm and thigh bones. Short bones. - The short bones are small pieces of bone ir- regularly shaped. Their texture is spongy throughout, excepting at their surface, where there is a thin crust of compact substance. Example - Bones of wrist and ankle. Flat bones. - Where the principal requirement is either ex- tensive protection or the provision of broad surfaces for muscular attachment, the bony tissue expands into broad or elongated flat plates. Example - Shoulder blade and cranial bones. The flat bones are composed of two thin layers of compact tissue, enclosing between them a variable quantity of cancellous tissue. In the bones of the skull this outer layer is thick and tough; the inner one, thinner, denser, and more brittle. The cancellated tissue lying between the two layers, or "tables of the skull," is called the diploe. Irregular bones. - The irregular bones are those which, on account of their peculiar shape, cannot be grouped under either of the preceding heads. Example - Vertebrae. If the surface of any bone is examined, certain eminences and depressions are seen. They are of two kinds: 1. Articular, 2. Non-articular. The articular are provided for the mutual con- nection of joints. The non-articular serve for attachment of ligaments and muscles. The following terms are used to describe such eminences, usually termed processes and depressions: - PROCESSES AND DEPRESSIONS 50 ANATOMY FOR NURSES [Chap. IV Spinous -■ A slender, sharp process. Example - Vertebra. Page 62. Tubercle - A small protuberance. Example - Humerus. Page 68. Crest - A firm ridge of bone. Example - Ilium. Page 72. Condyles (knuckles). - A rounded eminence. Example-• Femur. Page 73. Fossa (ditch).-A depression or cavity in or upon a bone. Example - Temporal. Page 55. Meatus or canal - A long tube-like passageway. Example -■ Haversian canals. Page 44. Foramen - A hole or orifice through which blood-vessels, nerves, and ligaments are transmitted. Example - Foramen Magnum. Page 52. Sinus - Antrum - Terms applied to cavities within certain bones. Example - Antrum of Highmore. Page 60. vertex Fig. 24. - Side View of the Skull. (Morrow.) Attention of the student is called to the text, page 60, where the word Mandible is used in preference to the term Inferior Maxillary which is found on the illustration. The word Maxilla is also used in preference to Superior Maxillary. Chap. IV] THE SKELETON 51 DIVISIONS OF THE SKELETON In taking up the various divisions of the skeleton, we will consider it as consisting of - 1. Head or skull Face. Cranium. 2. Hyoid. Vertebrae. Sternum. Ribs. 3. Trunk 4. Upper extremities. 5. Lower extremities. The head or skull. - The head or skull rests upon the spinal column, and is formed by the union of the cranial and facial bones. It is divisible into - 1. Cranium or brain case, and 2. Anterior region, or face. See note under Figure 24 regarding use of Mandible and Maxilla in preference to Infe- rior Maxillary and Superior Maxillary. Note also that the spelling of the word Lachrymal differs from the more correct spelling found in the text, as per the B. N. A. Fig. 25.-Front View of the Skull. (Morrow.) 52 ANATOMY FOR NURSES [Chap. IV Occipital (os occipitale) .... 1 Parietal (ossa parietalia) .... 2 Frontal (os frontale) 1 Temporal (ossa temporalia) ... 2 Sphenoid (os sphenoidale) ... 1 Ethmoid (os ethmoidale) .... 1 Occipital bone. - It is situated at the back and base of the skull. At birth the bone consists of four parts, which do not unite into a single bone until about the sixth year. The internal surface is deeply concave, and presents many eminences and BONES OF THE CRANIUM Fig. 26. - Occipital Bone. Inner surface. depressions for the reception of parts of the brain. There is a large hole - the foramen magnum - in the inferior portion of the bone, for the transmission of the medulla oblongata (the constricted portion of the brain) where it narrows down to join the spinal cord. At the foramen magnum it presents two proc- esses called condyles. Chap. IV] THE SKELETON 53 Parietal bones (paries, a wall). - The right and left form by their union the greater part of the sides and roof of the skull. The external surface is convex and smooth; the internal surface Fig. 27. - Parietal Bone. Inner surface. A, parietal depression; E, furrow for ramification of arteries. is concave, and presents eminences and depressions for lodging the convolutions of the brain, and numerous furrows for the ramifications of arteries which supply the brain with blood. Frontal bone. - It resembles a cockle shell, and not only forms the forehead, but also enters into the formation of the roof of the orbits, and of the nasal cavity. The arch formed by part of -Orbital Arch _ Hoof of Orbital Cavity Fig. 28. - Frontal Bone. 54 ANATOMY FOR NURSES [Chap. IV the frontal bone over the eye is sharp and prominent and affords that organ considerable protection from injury. In this bone are hollow spaces, called the frontal sinuses, which contain air, and two depressions called lacrimal fossse for the reception of the glands of the same name, which secrete the tears. At birth the bone consists of two pieces, which afterwards become united, along the middle line, by a suture which runs from the vertex of the bone to the root of the nose. This suture usually becomes obliterated within a few years after birth, but it occasionally remains throughout life. Temporal bones. - The right and left are situated at the sides and base of the skull. They are named temporal from the Latin word tempus, time, as it is on the temple the hair first becomes gray and thin, and thus shows the ravages of time. The temporal Fig. 29. - The Right Temporal Bone. Outer surface. The dotted lines indicate the lines of suture between squamous, mastoid, and tympanic portions. (Gerrish.) bones are divided into three parts---the hard, dense portion, called petrous; a thin and expanded scale-like portion, called squamous; and a mastoid portion, which is prolonged down- ward and forms the mastoid process. This process is filled with a number of connected cancellous spaces, containing air, and called mastoid cells.1 They communicate with the cavity of 1 Cells.-The student must bear in mind that the word cell is used with two different meanings in anatomy. Histologically speaking, the word Chap. IV] THE SKELETON 55 the middle ear. The condition known as mastoiditis means in- flammation of the lining of these cells. The internal ear, the essential part of the organ of hearing, is contained in a series of cavities, channelled out of the substance of the pe- trous portion. Be- tween the squamous and petrous portions is a socket, called the glenoid fossa, for the reception of the con- dyle of the lower jaw. Fig. 30.-Parietal, Temporal, and Sphenoid Bones. Posterior aspect. 1, body of sphenoid bone; 2, 2, greater wings of sphenoid bone; 3, 3, parietal bones; 4, 4, mastoid process of temporal bones. (Gould's Dictionary.) Sphenoid bone (sphen, a wedge). - It is situated at the anterior part of the base of the skull and just behind the ethmoid. It articulates with all the other cranial bones, which it binds firmly and solidly together. In form it somewhat resembles a bat with extended wings. Ethmoid bone. - It is an exceeding- ly light, spongy bone, placed between the two orbits at the upper part of the nose, contributing to form a part of each of these cavities. The portion of the bone situated at the back of the nose, which forms the roof of the nasal fossse and also closes the anterior part of the base of the skull Fig. 31. - Ethmoid Bone. Posterior surface. 2, cribri- form or perforated plate. " cell " refers to one of the component units of the body, such as an " epi- thelial cell" or "nerve-cell." In connection with the use of the words "mastoid cells" in the text, the word "cells" refers to tiny enclosed hol- low chambers similar to the cells of a honeycomb or the cells of a prison. 56 ANATOMY FOR NURSES [Chap. IV cavity, is pierced by numerous holes, through which the nerves conveying the sense of smell pass. Descending from the perfo- rated plate, on either side of the nasal cavity, are two masses of very thin, spongy, bony tissue ; these masses are known as the superior and middle turbinated processes. THE SKULL AS A WHOLE The bones of the cranium begin to develop at a very early period of foetal life. Thus, before birth the bones at the top and sides of the skull are separated from each other by membra- nous tissue in which bone is not yet formed, and being then imperfectly ossified, they are readily moulded, and they overlap one another more or less during parturition. The spaces at the angles of the bone occupied by the mem- branous tissue are termed the fontanelles, so named from the pulsations of the brain, which can be seen in some of them, rising like the water in a fountain. There are six of'these fontanelles. The anterior fontanelle is the largest, and is a lozenge-shaped space between the angles of the two parietal bones and the two segments of the frontal bone. It remains open until the second year, and occasionally persists throughout life. The posterior fontanelle is much smaller in size, and is a triangular space between the occipital and two parietal bones. This is closed by an extension of the ossifying process a few months after birth. (See Figs. 63 and 64.) Fig. 32. -Skull of New-born Child. To show moulding. (Edgar.) Fig. 33. - Skull of New-born Child. To show moulding. (Edgar.) Chap. IV] THE SKELETON 57 The other four fontanelles, two on each side of the skull, are placed at the inferior angles of the parietal bones; they are un- important.1 The base of the skull is much thicker and stronger than the walls and roof; it presents a number of openings for the passage of the cranial nerves, blood-vessels, etc. BONES OF THE FACE Nasal (ossa nasalia) 2 Lacrimal (ossa lacrimalia) 2 Vomer (os vomeris) 1 Malar (ossa malaria) 2 Palate (ossa palatina) 2 Inf. Turbinated (conchae nasalis . . . inferiores) . 2 Maxillae 2 Mandible (mandibula) 1 14 Nasal bones. - They are two small oblong bones placed side by side at the middle and upper part of the face, forming by their junction "the bridge" of the nose. They vary somewhat in size and form in different individuals. Lacrimal bones. - Are the smallest and most fragile bones of the face. They are situated at the' front part of the inner wall of the orbit, and resem- ble somewhat in form, thinness, and size, a finger-nail. Vomer. - It is a single bone placed at the lower and back part of the nasal cavity, and forms part of the central septum of the nasal fossae. It is thin, and shaped somewhat like a ploughshare, but varies in different individuals, being frequently bent to one or the other side. Malar, or yoke bone. - Forms the prominence of the cheek, and part of the outer wall and floor of the orbit. Fig. 34. - Nasal Bones. Viewed from before. (Ger- ris h.) Fig. 35. - Lacrimal Bone. 1 Small, irregular ossicles called sutural bones (wormian bones) are found in the sutures of the head, chiefly near the fontanelles. They often assist in the closure of the fontanelles. 58 ANATOMY FOR NURSES [Chap. IV Fig. 36. - Sagittal Section of Face, a little to the left of the Middle Line, showing the Vomer and its Relations. (Gerrish.) A prominent spine of bone projects backward from the body of the malar, and articulates by its free extremity with the cor- responding spine projecting forward from the temporal bone, thus making the two members of the true arch known as the zygomatic arch. Fig. 37. - Right Malar Bone. Outer surface. (Gerrisli.) Palate bones.-They are shaped like an "L," and form (1) the back part of the roof of the mouth; (2) part of the floor and outer wall of the nasal fossae; (3) a very small portion of the floor of the orbit. Inferior turbinated bones. - They are situated in the nostril, on the outer wall of each side. Each consists of a layer of thin, Chap. IV] THE SKELETON 59 SPH EN. PROCESS INF. TURB.J CREST Fig. 38. - The Two Palate Bones in their Natural Position. Dorsal view. (Gerrish.) spongy bone, curled upon itself like a scroll; hence its name, "turbinated." Maxillae,1 or upper jaw- bones.- The maxillae are two in number (right and left) and are the principal bones of the face. Each bone assists in forming (1) part of the floor of the orbit, (2) the floor and outer wall of the nasal fossae, (3) the greater part of the roof of the LACRIMAL PROCESS ETHMOID PROCESS. Fig. 39. - Right Inferior Turbinate Bone. External surface. (Gerrish.) NASAL ^PROCESS p N FRAORBITAL ' FORAMEN --NASAL NOTCH ©•fc. ANTERIOR NASAL SPINE POSTERIOR DEN TAL CANALS Fig. 40. - The Right Maxilla. Outer surface. (Gerrish.) 1 Also known as superior maxillary. 60 ANATOMY FOR NURSES [Chap. IV mouth.1 From a surgical point of view, it is one of the most important bones of the face, on account of the number of diseases to which some of its parts are liable. That part of the bone which contains the teeth is called the alveolar process, and is excavated into cavities, varying in depth and size according to the size of the teeth they contain. The body of the bone is hollowed out into a large cavity known as the antrum of Highmore. Mandible,2 or lower jaw-bone. - It is the largest and strongest bone of the face. At birth, it consists of two lateral halves, Fig. 41. - The Mandible. Viewed from the right and a little in front. (Gerrish.) ^"mental protuberance which join and form one bone during the first or second year. It serves for the reception of the lower teeth, and undergoes sev- eral changes in shape dur- ing life, owing mainly (1) to the first and second dentition, (2) to the loss of teeth in the aged, and (3) the subsequent absorp- tion of that part of the bone which contained them. It articulates, by its condyles, with the sockets in the temporal bones, which allows for free movement in mastication. Hyoid bone (os hyoideum). - Is an isolated U-shaped bone Fig. 42. - The Hyoid Bone. Viewed from the left and in front. (Gerrish.) 1 When the maxillae fail to unite before birth, we have the condition known as cleft-palate. 2 Also known as inferior maxillary. Chap. IV] THE SKELETON 61 lying in front of the throat, just above the laryngeal prominence (Adam's apple). It supports the tongue, and gives attachment to some of its numerous muscles. TRUNK The bones which enter into the formation of the trunk consist of the vertebrae, ribs, and sternum. CERVICAL VERTEBRZE THORACIC VERTEBRZE LUMBAR VERTEBRZE SACRUM COCCYX Fig. 43. - The Vertebral Column. Right lateral view and dorsal view, (Gerrish.) The vertebral column as a whole. - It is formed of a series of bones called vertebrae, and in a man of average height is about twenty-eight inches long. In youth the vertebrae are thirty-three 62 ANATOMY FOR NURSES [Chap. IV in. number, and according to the position they occupy are named: - Cervical (vertebrae cervicales), in the neck ... 7 Thoracic (vertebrae thoraceles), in the thorax . . 12 Lumbar (vertebrae lumbales), in the loins ... 5 Sacral (vertebrae sacrales), in the pelvis .... 5 Coccygeal (vertebrae coccygeae), in the pelvis . . 4 The vertebrae in the upper three portions of the spine are separate and movable throughout the whole of life, and are known as true vertebrae. Those found in the sacral and coccygeal re- gions are, in the adult, firmly united, so as to form two bonks, five entering into the upper bone, or sacrum, and four into the ter- minal bone of the spine, or coccyx. They are known as false vertebrae, and on account of their union the number of vertebrae in the adult is twenty-six. The bodies of the vertebrae are piled one upon another, forming a solid, strong pillar, for the support of the cranium and trunk, the arches forming a hollow cylinder behind for the protection of the spinal cord. Viewed from the side, it presents four curvatures: the first curve has its convexity forwards in the cervical region, and is followed, in the thoracic, by a curve with its concavity towards the chest. In the lum- bar region the curve has again its convexity forwards, while in the sacral and coccygeal regions the concavity is turned forwards. These curvatures confer a considerable amount of springi- ness and strength upon the spinal col- umn which would be lacking were it a straight column: the elasticity is further increased by broad, thin ligaments called ligamenta flava, con- necting the arches; and disks of fibro-cartilage lying between and connecting the bodies of the vertebrae. These disks or pads also mitigate the Spinous Process _ Articular Process I Transverse Process Fig. 44.-A Cervical. Vertebra. Chap. IV] THE SKELETON 63 effects of concussion arising from falls or blows, and allow of a certain amount of motion between the vertebrae. The amount of motion permitted is greatest in the cervical region. Between each pair of vertebrae are apertures called intervertebral foram- ina, through which the spinal nerves pass from the spinal cord. The vertebrae. - Each vertebra consists of two essential parts, an anterior solid portion or body, and a posterior portion or arch. Each arch has seven processes: four articular, two to connect with bone above, two for bone below; two transverse, one at each side* and one spinous process, projecting backward. The different vertebrae are connected together by means of the articular processes, and by disks of intervertebral fibro-cartilage COSTO-TRANS- VERSE FORAMEN. , VENTRAL ARCH. TRANSVERSE PROCESS. SPINAL FORAMEN. Fig. 45. - The Atlas. Viewed from above. (Gerrish.) placed between the vertebral bodies, while the transverse and spinous processes serve for the attachment of muscles which move the different parts of the spine. In the cervical region of the vertebral column the bodies of the vertebrae are smaller than in the thoracic, but the arches are larger; the spinous processes are short, and are often cleft in two, or bifid. The first and second cervical vertebrae differ con- siderably from the rest. The first, or atlas, so named from supporting the head, has practically no body, and may be described as a bony ring divided into two sections by a transverse ligament. The dorsal ODONTOID PROCESS.- ARTICULAR FACET - FOR VENTRAL ARCH OF ATLAS. SPINOUS PROCESS. Fig. 46. - The Epistropheus (Axis). Its right side. (Gerrish.) TRANSVERSE PROCESS. 64 ANATOMY FOR NURSES [Chap. IV section of this ring contains the spinal cord, and the ventral or front section contains the bony projection which arises from the upper surface of the body of the second cervical vertebra, epi- stropheus (axis). This bony projection, called the odontoid pro- cess, forms a pivot, and around this pivot the atlas rotates when the head is turned from side to side, carrying the skull, to which it is firmly articulated, with it. The bodies of the tho- racic vertebrae are larger and stronger than those of the cervical; they contain depressions for the reception of the vertebral ends of the ribs. The bodies of the lumbar vertebrae are the largest and heaviest in the whole spine. Imeskard. Fig. 47.-Thorax. (10th rib is defective ; it should be attached to the costal cartilage above.) Chap. IV] THE SKELETON 65 Sacrum (os sacrum). - The sacrum is formed by the union of the five sacral vertebrae. It is a large triangular bone situated like a wedge between the coxal bones, and is curved upon itself in such a way as to give increased capacity to the pelvic cavity. Coccyx (os coccygis). - The coccyx is usually formed of four small segments of bone, and is the most rudimentary part of the vertebral column. THORAX The thorax is an elon- gated bony cage formed by the sternum and costal cartilages in front, the twelve ribs on each side, and the bodies of the twelve thoracic ver- tebra) behind. It con- tains and protects the principal organs of res- piration and circulation. Sternum, or breast bone. - Is a flat, narrow bone about six niches long, situated in the median line in the front of the chest, and may be likened to a short, flat sword. It consists of three portions. The upper part is termed the handle, or manubrium ; the middle and largest piece is termed the body, or gladiolus; the inferior portion is termed the ensiform, or the xiphoid process. On both sides of the upper and middle pieces are notches for •FOR FIRST COSTAL CARTILAGE. -FOR SECOND COSTAL CARTILAGE. - FOR THIRD COSTAL CARTILAGE* FOR FOURTH COSTAL CARTILAGE. ,FOR FIFTH COSTAL CARTILAGE -FOR SIXTH COSTAL CARTILAGE. ">FOR SEVENTH COSTAL CARTILAGE. Fig. 48. - The Sternum, Ventral aspect (Gerrish.) 66 ANATOMY FOR NURSES [Chap. IV the reception of the sternal ends of the costal cartilages. The ensiform or xiphoid process is cartilaginous in structure in early life, but is more or less ossified at the upper part in the adult; it has no ribs attached to it. Ribs (costae). - They are elastic arches of bone, forming the chief part of the thoracic wall (vide Fig. 47). They are usually twelve in number on each side. They are all connected behind with the vertebrae, and the first seven ^airs are connected with the sternum in front through the intervention of the costal cartilages; these first seven pairs are called from their attach- ment the true ribs. The remaining five pairs are termed false ribs; of these, the first three, eight, nine, and ten, are attached in front to the costal cartilages of the next rib above. The two remaining, being unattached in front, are termed floating ribs. Fig. 49. - The Eighth Rib of the Right Side. Viewed from behind. (Gerrish.) The convexity of the ribs is turned outwards so as to give roundness to the sides of the chest and increase the size of its cavity; each rib slopes downwards from its vertebral attach- ment; so that its sternal end is considerably lower than its dorsal. The spaces left between the ribs are called the intercostal spaces. BONES OF THE UPPER EXTREMITIES Clavicle (clavicula, or collar bone) .... 2 Scapula (shoulder blade) ' 2 Humerus (arm) 2 Ulna - 2 Radius - 2 (forearm) 4 Carpus (wrist) 16 Metacarpus (palm of hand) 10 Phalanges (fingers) 28 64 Chap. IV] THE SKELETON 67 Thus enumerated, we see that the bones of the upper ex- tremities consist of - 1. Shoulder girdle ' Clavicle. Scapula. 2. Arm (humerus). 3. Forearm (radius and ulna). 4. Hand Wrist. Body of hand. Fingers. ICONOID A^TUBERCLE Fig. 50. - The Right Clavicle. Upper surface. (Gerrish.) Clavicle, or collar bone. - It is a long bone and forms the an- terior portion of the shoulder girdle. It articulates with the sternum by its inner extremity, which is called the sternal ex- Spine Coracoid process Acromion process Glenoid cavity Fig. 51. - The Scapula, or Shoulder Blade. (Morrow.) 68 ANATOMY FOR NURSES [Chap. IV tremity. Its outer or acromial extremity articulates with the scapula. In the female, the clavicle is generally less curved, smoother, and more slender than in the male. In those persons who perform considerable manual labour, which brings into constant action the muscles connected with this bone, it acquires considerable bulk. Scapula, or shoulder blade. - It forms the back part of the shoulder girdle. It is a large flat bone, triangular in shape, placed between the second and seventh, or sometimes eighth, ribs on the back part of the thorax. It is unevenly divided on its dorsal surface by a very prominent ridge, the spine of the scapula, which terminates in a large triangular projection called the acromion process, or summit of the shoulder. Below the acromion process, and at the head of the shoulder blade, is a shallow socket, the glenoid cavity, which receives the head of the humerus. Humerus, or arm bone. - The humerus is the longest and largest bone of the upper limb. The upper extremity of the bone consists of a rounded head joined to the shaft by a con- stricted neck, and of two eminences called the larger and smaller tubercles. The head articulates with the glenoid cavity of the scapula. The con- stricted neck above the tubercles is called the anatomical neck, and that, below the tubercles Anatomical neck. Larger tubercle ■ Head ■ Smaller tubercle Surgical neck Condyles Fig. 52. - The Humerus, or Arm Bone. (Morrow.) Chap. IV] THE SKELETON 69 the surgical neck, from its being often the seat of fracture. The lower extremity of the bone is flattened from before backwards into a broad articular surface, which is divided by a slight ridge into two parts, by means of which it articulates with ulna and radius. Ulna, or elbow bone. - It is placed at the inner side (little finger side) of the forearm, paral- lel with the radius.1 Its upper extremity presents for examina- tion two large curved processes and two concave cavities; the larger process forms the head of the elbow, and is called the ole- cranon process. The lower ex- tremity of the ulna is of small size, and is excluded from the wrist by a piece of fibro-cartilage. Radius. - It is situated on the outer side of the forearm. The upper end is small and rounded, with a shallow depression on its upper surface for articulation with the humerus, and a promi- nent ridge about it, like the head of a nail, by means of which it rotates within the lesser sigmoid cavity of the ulna. The lower end of the radius is large, and forms the chief part of the wrist. Carpus, or wrist. - The wrist is composed of eight small pieces of bone (ossa carpi) united by ligaments; they are arranged in two rows, and are closely welded together, yet by the arrange- ment of their ligaments allow of a certain amount of motion. They afford origin by their palmar surfaces to most of the short muscles of the thumb and little finger, and are named from their shape as follows: - .Olecranon Fig. 53.-The Bones or the Fore- arm. (Morrow.) 1 Anatomists in describing the body always consider it as being in the erect position, with the arms hanging and the palms of the hands looking forwards. 70 ANATOMY FOR NURSES [Chap. IV 1st row. Scaphoid (os naviculare manus) 1 ...... 1 Semilunar (os lunatum) 1 Cuneiform (os triquetrum) 1 Pisiform (os pisiforme) 1 2d row. Trapezium (os multangulum majus) 1 Trapezoid (os multangulum minus) 1 Os Magnum (os capitatum) 1 Unciform (os hamatum) 1 8 Metacarpus, or body of hand. - Each metacarpus is formed by five bones (ossa metacarpalia). The bones are curved longi- tudinally, so as to be convex behind, concave in front; they articulate by their bases with the bones of the wrist and with one another, and the heads of the bones articulate with the phalanges. Phalanges, or digits. - They are the bones of the fingers; and are fourteen in number in each hand, three for each finger, and two for the thumb. The first row articulates with the metacarpal bones and the second row of phalanges; the second row, with the first and third; and the third, with the second row. BONES OF THE LOWER EXTREMITIES Ossa coxae or ossa innominata (hip bones) . . 2 Femur (thigh bone) 2 Patella (knee-cap) 2 Tibia (shin bone) 21. Fibula (calf bone) 21 Tarsus (ankle, or root of foot) 14 Metatarsus (sole and instep) 10 Phalanges (toes) 28 62 The bones of the lower extremities correspond to a great extent with those of the upper extremities, and bear a rough resemblance to them, but are heavier and more firmly knit together. They consist, as stated above, of: - 1 The names given in brackets are according to the B. N. A. Chap. IV] THE SKELETON 71 1. Hip bones (which form principal part of pelvic girdle). 2. Thigh (femur). 3. Leg (tibia and fibula). 4. Foot (ankle,, sole, instep, toes). FIRST PHALANX SECOND PHALANX jl THIBO PHALANX Fig. 54.-The Bones of the Right Hand. Palmar aspect. (Gerrish.) Os coxae, or hip bone. - It is a large, irregular-shaped bone, which, with its fellow of the opposite side, forms the sides and front wall of the pelvic cavity. In young subjects it consists 72 ANATOMY FOR NURSES [Chap. IV of three separate parts, and although m the adult these have become united, it is usual to describe the bone as divisible into three portions: (1) the ilium (os ilium), (2) the ischium (os ischii), (3) the pubis (os pubis). The ilium, so called from its supporting the flank, is the upper broad and expanded portion which forms the prominence of the hip. The ischium is the lower and strongest portion of the bone, while the pubes is that portion which forms the front of the pelvis. Where these three portions of the bone meet and finally ankylose is a deep socket, called the acetab- ulum, into which the head of the femur fits. Other points of special interest to note in the coxal bones are: - (1) The spinous process formed by the projection of the crest of the ilium in front, which is called the anterior su- perior spinous process, and which is a well-known and conven- ient landmark in making anatomical measurements. (2) The largest foramen in the skeleton, known as the door- like or thyroid foramen, situated between the ischium and pubes. (3) The symphysis pubis, or pubic articulation, which also serves for a convenient landmark in making measurements. Femur, or thigh bone. - It is the longest, largest, and strongest bone in the skeleton. The upper extremity of the femur, like that of the humerus, consists of a rounded head joined to the shaft by a constricted neck, and of two eminences, called the greater and lesser trochanters. The head articulates with the cavity in the os coxa;, called the acetabulum. The lower ex- tremity of the femur is larger than the upper, is flattened from before backwards, and divided into two large eminences or condyles by an intervening notch. It articulates with the tibia and the patella, or knee-cap. In the erect position it is not Fig. 55. - Development of the Hip Bone. Showing the union of the three portions in the acetabulum. (Ger- rish.) Chap. IV] THE SKELETON 73 vertical, being separated from its fellow above by a considerable interval, which corresponds to the entire breadth of the pelvis, but the bone inclines gradually downwards and inwards, so as to approach its fellow towards its lower part, in order to bring the knee-joint near the line of gravity of the body. The degree of inclination varies in differ- ent persons, and is greater in the female than the male, on account of the greater breadth of the pelvis. Patella, or knee-cap. - It is the largest sesamoid bone in the body. It is small, flat, triangular in shape, and placed in front of the knee- joint, which it serves to protect. It is separated from the skin by a bursa. (See page 123.) Tibia, or shin bone. - Is situated at the front and inner side of the leg. The upper extremity is large, and expanded into two lateral eminences with concave surfaces, which receive the condyles of the femur. The lower ex- tremity is much smaller than the upper; it is prolonged downwards on its inner side into a strong process, the medial (or inner) malleolus. It articulates with the fibula and one of the bones of the ankle. (In the male, its direction is vertical and parallel with the bone of the opposite side; but in the female it has a slight oblique Greater trochanter Head Neck Lesser trochanter Condyles Fig. 56. - The Femur, or Thigh Bone. (Morrow.) Fig. 57.--The Patella, or Knee-cap. (Morrow.) 74 ANATOMY FOR NURSES [Chap. IV direction outwards, to com- pensate for the oblique direc- tion of the femur inwards.) Fibula, or calf bone. - Is situated at the outer side of the leg. It is the smaller of the two bones, and, in propor- tion to its length, the most slender of all the long bones; it is placed nearly parallel with the tibia. The upper extremity consists of an irreg- ular quadrate head by means of which it articulates with the tibia. The lower extrem- ity is prolonged downwards into a pointed process, the lateral (or external) malleolus, which lies just beneath the skin. It articulates with the tibia and one of the bones of the ankle. Tarsus. - The tarsus is composed of seven small pieces of bone, united by ligaments, but the tarsal bones differ from the carpal in being larger and more irregularly shaped. The largest and strongest of the tarsal bones is called the calcaneum, or heel bone; it serves to transmit the weight of the body to the ground, and forms a strong lever for the muscles of the calf of the leg. The names are as follows: - Calcaneum (calcaneus) 1 1 Astragalus (talus) 1 Cuboid (os cuboideum) 1 Scaphoid (os naviculare pedis) 1 External cuneiform (os cuneiforme primum) . 1 Middle cuneiform (os cuneiforme secundum) . 1 Internal cuneiform (os cuneiforme tertium) . . 1 7 Lateral malleolus' Medial malleolus Fig. 58. - The Bones of the Leg. (Morrow.) 1 The names given in brackets are according to the B. N. A. FIRST PHALANX- OF FIFTH TOE FIRST PHALANX OF HALLUX Fig. 59. The Bones oe the Right Foot. Viewed from above. (Gerrish.) 75 76 ANATOMY FOR NURSES [Chap. IV Metatarsus, or sole and instep of foot, is formed by five bones. These metatarsal bones closely resemble the metacarpal bones Fig. 60. - Female Pelvis. of the hand. Each bone articulates with the tarsal bones by one extremity, and by the other with the first row of phalanges. Fig. 61. - Male Pelvis. Chap. IV] THE SKELETON 77 Phalanges, or digits. - Both in number and general arrange- ment resemble those in the hand, there being two in the great toe and three in each of the other toes. PELVIS The pelvis, so called from its resemblance to a basin, is stronger and more massively constructed than either the cranial or the thoracic cavity. It is composed of four bones, the two coxal bones forming sides and front, the sacrum and coccyx com- pleting it behind. It is divided by a brim or prominent line, the linea ilio-pectinea, into the large (false) and small (true) pelvis. The large pelvis is all that expanded portion of the pelvis situated above the brim; it forms an incomplete or "false" basin. The small pelvis is all that portion situated below the brim. Its cavity is a little wider in every direction than the brim itself, while the large pelvis is a great deal wider. The brim is, therefore, a narrowed bony ring or aperture between these two cavities; hence it is often termed the "strait"; while the space included within the strait, or brim, is called the "inlet." The small (true) bony pelvis is a basin with incomplete walls of bone, the bottom of which is composed of the softer tissues, muscles, and ligaments. The opening below is called the " in- ferior strait," or "outlet." The female pelvis differs from that of the male in those par- ticulars which render it better adapted to parturition, notably in being wider in every direction, which gives more room for the child to pass; in being shallower, which lessens the distance through which the child has to be propelled; and lastly, in the bones being thinner and smoother. SUMMARY 1. Organs of support. 2. Instruments of locomotion. 3. Framework of hard material. 4. Afford attachment to soft parts. 5. Shelter delicate structures. 6. Shape to whole body. Bones Classification: - 1. Long. 2. Short. 3. Flat. 4. Irregular. 78 ANATOMY FOR NURSES [Chap. IV TABLE OF THE BONES HEAD Occipital 1 Parietal 2 Frontal 1 Temporal 2 Sphenoid 1 Ethmoid 1 8 Cranium Face Nasal 2 Lacrimal 2 Vomer 1 Malar 2 Palate 2 Inferior turbinated .... 2 Maxilla 2 Mandible 1 14 Ear Malleus 2 Incus . „ 2 Stapes 2 Hyoid bone in the neck 1 Trunk Cervical .7 Thoracic 12 Lumbar 5 Sacral 1 Coccygeal 1 Vertebrae . . 26 Ribs 24 Sternum 1 51 Clavicle 1 Scapula 1 Humerus 1 Ulna 1 Radius • . 1 Upper Extremity Os coxae 1 Femur 1 Patella 1 Tibia 1 Lower Extremity Scaphoid . . . . 1 Semilunar . . . 1 Cuneiform . . . 1 Pisiform . . . . 1 Trapezium . . . 1 Trapezoid . . . 1 Os magnum . . . 1 „ Unciform. . . . 1 Fibula 1 Calcaneum . . . 1 Astragalus . . . 1 Cuboid . . . . 1 Scaphoid . . . . 1 External cuneiform 1 Middle cuneiform 1 . Internal cuneiform 1 Carp"S Tarsus Metatarsus 5 Phalanges 14 31 31 x 2 = 62 Metacarpus 5 Phalanges . 14 32 32 x 2 = 64 CHAPTER V ARTICULATIONS Articulations or joints. - The various bones of which the skeleton consists are connected together at different parts of their surfaces, and such connections are called articulations or joints. CLASSIFICATION Joints are classified according to motion and according to the substances by which they are united. In all instances some softer substance is placed between the bones, uniting them together or clothing the opposed surfaces; but the manner in which the several pieces of the skeleton are thus con- nected varies to a great degree. We distinguish three varie- ties; viz.:- 1. Synarthroses, or immovable joints. 2. Amphiarthroses, or slightly movable joints. 3. Diarthroses, or freely movable joints. SYNARTHROSES, OR IMMOVABLE JOINTS The bones are connected by fibrous tissue or cartilage. The bones of the cranium and the facial bones (with the ex- ception of the lower jaw) have their adjacent surfaces applied in close contact, with only a thin layer of fibrous tissue placed between their mar- gins. In most of the cranial bones this union occurs by means of toothed edges which dovetail into one another and form jagged lines of union known as sutures. The three most important sutures are as follows: - Fig. 62. -A Toothed, or Dentated Suture. 79 80 ANATOMY FOR NURSES [Chap. V Fig. 63. - Diameters and Landmarks of the Fcetal Skull. Upper surface. (Edgar.) (1) Coronal.-The line of union between the frontal and parietal bones. (2) Lambdoidal.- The line of union between the parietal and occipital bones. (3) Sagittal, or greater suture. - This begins at the base of the nose, extends along the middle line on the top of the crown, separates the frontal bone into two parts, the parietal bones from each other, and ends at the posterior fontanelle. Synchondrosis is usually a temporary form of joint. The cartilage between the bones ossifies before adult life. Example: the union of the sphenoid and occipital bones. Chap. V] ARTICULATIONS 81 Fig. 64. -Diameters and Landmarks of the Fcetal Skull. Posterior surface. (Edgar.) AMPHIARTHROSES, OR SLIGHTLY MOVABLE JOINTS In this form of articulation the bony surfaces are usually joined together by broad, flattened disks of fibro-cartilage, as in the articulations between the bodies of the vertebrae. These intervertebral disks being compressible and extensile, the spine can be moved to a limited extent in every direction. In the pelvis the articulation between the two pubic bones (symphysis pubis), and between the sacrum and ilia (sacro-iliac articu- lation), are slightly movable. The pubic bones are united by a disk of fibro-cartilage and by ligaments. In the sacro-iliac articulation the sacrum is united more closely to the ilia, the articular surfaces being covered by cartilage and held together by ligaments. Fig. 65. - A Slightly Mov- able Joint. a, b, disk of fibro-cartilage ; c, articular cartilage ; d, bone. 82 ANATOMY FOR NURSES [Chap. V A certain limited motion of these joints (symphysis pubis and sacro-iliac) is essential to a normal birth. The fibro-carti- lage becomes thickened and softened during pregnancy. DIARTHROSES, OR FREELY MOVABLE JOINTS This division includes the complete joints, and are the only joints in which the three following conditions are found: - (1) A secreting membrane (synovial) placed between the opposing surfaces, which keeps them well lubricated and capable of free movement one upon the other. (See Synovial Membrane, Chapter VII.) (2) Each articular end of the bone is covered by hyaline carti- lage, which provides surfaces of remarkable smoothness, and these surfaces are lubricated by the synovial fluid secreted from the delicate synovial membrane which lines the cavity of the joint. This membrane is continu- ous with the margin of the articular cartilage, and along with them completely encloses the joint cavity. (3) The bones are united by fibrous ligaments, forming more or less perfect capsules. The ligaments are not always so tight as to maintain the bones in close contact in all positions of the joint, but are rather tightened in some positions and relaxed in others, so that in many cases they are to be looked on chiefly as controllers of movements, and not as serving solely to hold the bones together. The bones are mainly held together in these joints by atmospheric pressure and by the surrounding muscles. The varieties of joints in this class have been determined by the kind of motion permitted in each. They are as follows: - (1) Arthrodia, or gliding joint.-The articular surfaces are nearly flat, and admit of only a limited amount of gliding move- ment, as in the joints between the articular processes of the vertebrae. (2) Ginglymus, or hinge joint. - The articular surfaces are of Fig. 66. - A Complete Joint. The synovial membrane is represented by dotted lines. Chap. V] ARTICULATIONS 83 such shape as to permit of movement to and fro in one plane only, like a door on its hinges. These movements are called flexion and extension, and may be seen in the articulation of the arm with the forearm, in the ankle joint, and in the articu- lations of the phalanges. (3) Enarthrosis, or ball and socket joint. - In this form of joint a more or less rounded head is received into a cup-like cavity, as the head of the femur into the acetabulum, and the head of the humerus into the glenoid cavity of the scapula. Movement can take place freely in any direction, but the shal- lower the cup, the greater the extent of motion. The shoulder joint is the most freely movable joint in the body. (4) Trochoides, or pivot joint. - In this form, one bone rotates around another which remains stationary, as in the articulation of the atlas with the epistropheus (axis) and in the articulation of the ulna and radius. In the articulation of the ulna and radius the ulna remains stationary, and the radius rotates freely around its upper end. The hand is attached to the lower end of the radius, and the radius, in rotating, carries the hand with it; thus, the palm of the hand is alternately turned forwards and backwards. When the palm is turned forwards, the atti- tude is called supination; when backwards, pronation. (5) Condylarthrosis, or condyloid joint.-When an oval- shaped head, or condyle, of a bone is received into an elliptical cavity, it is said to form a condyloid joint. An example of this kind of joint is found in the metacarpo-phalangeal articulations. The rounded heads of the metacarpal bones are received in the cup-shaped bases of the phalanges. (6) Reciprocal reception, or saddle joints. - In this joint the articular surface of each bone is concave in one direction, and convex in another, at right angles to the former. A man seated in a saddle is "articulated" with the saddle by such a joint. For the saddle is concave from before backwards, and convex from side to side, while the man presents to it the concavity of his legs astride, from side to side, and the convexity of his seat, from before backwards. The metacarpal bone of the thumb is articulated with the wrist by a saddle joint. Both the condy- loid and the saddle joints admit of motion in every direction except that of axial rotation. 84 ANATOMY FOR NURSES [Chap. V The different kinds of movement of which bones thus con- nected are capable are: - 1. Flexion. -A limb is flexed, when it is bent. 2. Extension. - A limb is extended, when it is straightened out. 3. Abduction. - Means drawn away from the middle line of the body. 4. Adduction. - Means brought to or nearer the middle line of the body. 5. Rotation. - Means made to turn on its own axis. 6. Circumduction. - Means made to describe a conical space by rotation around an imaginary axis. No part of the body is capable of perfect rotation, as a wheel, for the simple reason that such motion would necessarily tear asunder all the vessels, nerves, muscles, etc., which unite it with other parts. Sprain.-A wrenching or twisting of a joint accompanied by a stretching or tearing of the ligaments or tendons is called a sprain. SUMMARY Articulations or Joints - connections existing between bones. Sutura. - Articulations by processes and indentations interlocked to- gether. A thin layer of fibrous tissue is interposed between the bones. Sutures may be dentated, dove-tailed; serrated, saw-like; squamous, scale-like; harmonic, smooth ; and grooved, for the re- ception of thin plates of bone. Synchondrosis. - Temporary joint. Cartilage between bones ossifies in adult life. Synarthrosis, or Immovable Joint Bones are con- nected by fi- brous tissue or cartilage. 1. Symphysis. - The bones are united by a plate or disk of fibro- cartilage of considerable thick- ness. 2. Syndesmosis The bony surfaces are united by an interosseous liga- ment, as in the lower tibio-fibular articulation. Amphiarthrosis, r or Slightly r Bones are con- nected by disks of cartilage or interosseous ligaments. Chap. V] ARTICULATIONS 85 1. Arthrodia. - Gliding joint; artic- ulates by plane surfaces which glide upon each other. 2. Ginglymus.- Hinge or angular joint; moves backwards and for- wards in one plane. 3. Enarthrosis.- Ball and socket joint; articulates by a globular head in a cup-like cavity. 4. Trochoides.- Pivot joint; articu- lates by a pivot process turning within a ring, or by a ring turning round a pivot. 5. Condylarthrosis. -Condyloid joint; ovoid head received into elliptical cavity. 6. Reciprocal Reception. - Saddle joint; articular surfaces are con- cavo-convex. 1. Synovial mem- brane lining fibrous capsule. 2. Hyaline car- tilage covering articular ends of bones. 3. Fibrous liga- ments forming a capsule. Diarthrosis, or Movable Joint ' Flexion. Extension. Abduction. Adduction. Rotation. Circumduction. Movement . . . CHAPTER VI MUSCULAR TISSUE: STRIATED, OR STRIPED; NON-STRIATED OR PLAIN; ATTACHMENT OF MUSCLES TO SKELETON; PROMINENT MUSCLES OF HEAD AND TRUNK; PROMI- NENT MUSCLES OF LIMBS MUSCULAR TISSUE Is the tissue by means of which the active movements of the body are produced. It is more highly specialized than con- nective tissue. Muscles constitute the fleshy parts and form a large proportion of the weight of the whole body. The fol- lowing has been calculated for a man of one hundred and fifty pounds' weight from the tables of Liebig: skeleton, twenty-eight pounds; muscles, sixty-two pounds; blood, twelve pounds; viscera (with skin, fat, etc.), forty-eight pounds. Contractility. - Muscular tissue is irritable, and if we irritate or stimulate it, it will respond. We may irritate or stimulate the bones, ligaments, or other connective tissue structures, and they will not respond; they will remain immovable; if, however, we stimulate muscular tissue, it will show its response to the stimulation by contracting. This power of the muscle to con- tract is called muscular contractility. Under normal conditions there is a constant and insensible tendency to contract called tonicity. All muscular tissue consists of fibres, and whenever a muscle fibre contracts, it tends to bring together its two ends, with whatever may be attached to them. Influences which irri- tate or stimulate muscle fibres are spoken of under the general name of stimuli, and are usually of nervous origin. CLASSIFICATION Muscle fibres are of two different kinds, and we-therefore dis- tinguish two varieties of muscular tissue: - 86 Chap. VI] MUSCULAR TISSUE 87 (1) The striped, or striated, which is nearly always under the control of the will, and is often spoken of as voluntary muscle; also spoken of as skeletal because of attachment to bones which they move or assist in holding in place. (2) The plain, or non-striated, is usually withdrawn from the control of the will, and is often termed involuntary muscle. This kind of muscle is found arranged around the blood-vessels and hollow viscera, hence called visceral. The muscle of the heart is the one exception, as it is striated muscle, but involuntary. Voluntary, striated muscle is composed of long slender fibres measuring on an average about inch (0.050 mm.) in diameter, but having a length of an inch or more. Each fibre consists of three distinct elements: - (1) Contractile substance, forming the centre and making up most of the bulk of the fibres; (2) Nuclei; which lie scattered upon the surface of the contractile substance; (3) The sarcolemma, a thin structureless tube which tightly encloses the contractile substance and the nuclei. The muscle fibres lie closely packed, their ends lapping over on to adjacent fibres and forming bundles. These bundles are grouped so as to make larger bundles and are supported by a framework of con- nective tissue. If we examine a fresh muscle fibre microscopically, we see that the contractile substance is made up of still finer fibres or fibrillae, and these are marked with very fine, indistinct longitudinal lines, and in addition to the longitudinal lines it is crossed by more distinct narrow dark and light stripes, or striae, hence called striated. The relative width of the stripes varies according as the fibre is seen in a state of contraction or relaxation. The striated muscles are all connected with nerves, and under normal conditions do not contract otherwise than by the agency of the nerves. They are also plentifully supplied with blood- vessels. Fig. 67. - Diagram of Muscle Fibre with Sar- COLEMMA ATTACHED. 88 ANATOMY FOR NURSES [Chap. VI Involuntary, non-striated, visceral muscle is composed of elongated fibre-cells. Each fibre-cell contains a narrow, elongated nucleus. The sub- stance of the fibre-cell is lon- gitudinally lined, but does not exhibit transverse striation, hence called non-striated. The fibre-cells lie side by side, or lay over one another at the ends, and are joined together by a small amount of cement substance. The fibres are va- riously grouped in different parts of the body; sometimes crowded together in solid bundles, which are arranged in layers and surrounded by connective tissue, as in the in- testines; sometimes arranged in narrow, interlacing bundles, as in the blad- der; sometimes wound in single or double layers around the blood-vessels; and again, running in various directions and associated with bands of connective tissue, they form large, compact masses, as in the uterus. Numerous nerves are supplied to non- striated muscular tissue, and many blood- vessels. The contraction of this kind of muscular tissue is usually slower, and lasts longer than the contraction of the striated variety. As a general rule the muscles of the skeleton Fig. 68. -Wave of Contraction pass- ing over a Muscular Fibre of Dytiscus. (Very highly magnified.) R, R, portions of the fibre at rest ; C, contracted part ; I, I, intermediate condition. (Schafer.) Fig. 69. -Fibre-cells of Plain Muscular Tissue. (Highly magni- fied.) Chap. VI] MUSCULAR TISSUE 89 are thrown into contraction only by nervous impulses reaching them along their nerves; spontaneous contractions, as in a case of "cramps," being rare and abnormal. The plain muscular tissue of the internal organs, however, very often contracts in- dependently of the central nervous system, and by its contrac- tion it modifies the capacity of the cavities which it surrounds. Under favourable circumstances it will continue to contract after the viscera have been removed from the body. The great increase in the muscular tissue of the uterus during gestation takes place both by elongation and thickening of the preexisting fibre- cells, and also, it is thought, by the development of new fibre-cells from small granular cells lying in the tissue. In the shrinking of the uterus after parturition the fibre-cells diminish to their previous size, many of them become filled with fat granules, and eventually many are, doubt- less, removed by absorption. Muscles. - The muscles are separate organs, each muscle having its own sheath of connective tissue, called epimysium. They vary greatly in shape and size. In the trunk the muscles are broad, flattened, and expanded, forming the walls of the cavities which they enclose. In the limbs they are of con- siderable length, forming more or less elongated straps. A typical muscle is described as consisting of a body and two extremities. The body is the red contracting part, and the extremities are the ends where they are attached. Attachment of the muscles to the skeleton. - They are attached to the bones, cartilages, ligaments, and skin in various ways, the most common mode of attachment being by means of tendons. The muscular fibres converge as they approach their tendinous extremities, and gradually blend with the fibres of the tendons, the tendons in their turn inserting their fibres into the bones. Where one muscle connects with another, the muscles end in expanded form in flat, fibrous membranes called aponeurosis. Again, in some cases, the muscles are connected with the bones, cartilages, and skin, without the intervention of tendons or aponeuroses. Origin and insertion. - It is customary to speak of the attach- ments of their opposite ends under the names of origin and insertion, the first term origin being usually applied to the more fixed attachment; the second term insertion being applied to Fig. 70. - Forms of Muscles and Tendons. A, adductor of thigh ; B, biceps of arm ; D, deltoid ; G, gastrocnemius ; P', pronator of fore-arm ; P", pectoral ; R, rectus abdominis ; R", rectus muscle of thigh ; S', serratus magnus of thorax ; S", semi-membranosus of thigh. 90 Chap. VI] MUSCULAR TISSUE 91 the more movable attachment. The origin is, however, abso- lutely fixed in only a very small number of muscles, such as those of the face, which are attached by one end to the bone, and by the other to the movable skin. In the greater number, the muscle acts at both ends. The total number of voluntary muscles may be stated at about five hundred. It is not necessary for us to distinguish more than a few of the most prominent. We may conveniently classify these in four groups: - 1. Chief muscles of the head, face, and neck. 2. Chief muscles of the trunk. 3. Chief muscles of the upper extremities. 4. Chief muscles of the lower extremities. CHIEF MUSCLES OF HEAD, FACE, AND NECK Occipito-frontalis.-The chief muscles of the head are the occipital and frontal muscles, which, united together by a thin aponeurosis extending over and covering the whole of the upper part of the cranium, are usually known as one muscle, the occipito-frontalis, or epicranial. The occipital takes its origin from the occipital bone, and is inserted in the aponeurosis. The frontal takes its origin from the aponeurosis, and is in- serted in the tissues of the eyebrows. The frontal portion of this muscle is the more powerful; by its contraction the eye- brows are elevated, the skin of the forehead thrown into trans- verse wrinkles, and the scalp drawn forward. The occipital acts in direct line with the frontal. There are about thirty facial muscles; they are chiefly small, and control the movements of the eye, nose, and mouth. Six muscles'of eyeball. - The six muscles which move the eye- ball are the four straight, or recti, and the two oblique, muscles. The four recti have a common origin at the apex of the orbit; they pass straight forwards to their insertion into the eyeball, one, the superior rectus, in the middle line above; one, the inferior rectus, opposite it below, and midway on each side, the external and internal recti The eyeball is completely em- bedded in fat, and these muscles turn it as on a cushion, the superior rectus inclining the axis of the eye upwards, the infe- 92 ANATOMY FOR NURSES [Chap. VI Fig. 71.-'Superficial Muscles of Head and Neck. (Gerrish.) rior downwards, the external outwards, the internal inwards. The superior oblique muscle arises from the apex of the orbit (the same as the four recti), courses forward to the upper and inner angle of the orbit, where it passes through a loop of carti- lage. Then it bends at an acute angle, passes around the upper part of the eyeball, and is inserted between the superior and external recti. The inferior oblique arises from the orbital plate of the maxilla, courses around the under portion of the eyeball to its attach- Chap. VI] MUSCULAR TISSUE 93 ment near the external rectus. The action of the two oblique muscles is somewhat complicated, but their gen- eral tendency is to roll the eyeball on its own axis. Orbital muscles. - The six muscles already described are attached to the eyeball, but the orbit contains a seventh, hence we count seven orbital muscles. The levator palpebrae superioris (lifter of the upper lid) arises from the back of the orbit, passes forward, and is inserted into the tarsus of the upper lid. It elevates the upper lid and opens the eye. The muscles of mastication. --They are: 1. the masseter (chewing muscle), 2. the tem- poral (temple muscle), 3. the external pterygoid, and 4. the internal pterygoid. They all have their origin in the immovable bones of the skull, and are inserted into the movable lower jaw. They generally act in concert, bringing the lower teeth forcibly into contact with the upper; they also move the lower jaw forward upon the upper, and in every direc- tion necessaiy to the process of grinding the food. Buccinator (trumpeter's muscle) .-This muscle is usually classed with the muscles of expression, but as its action is to close the mouth and keep the food between the teeth, its office during mastication is important. It arises from the alveolar processes of the maxilla and mandible, and is inserted into the orbicular or lip muscles. Orbicularis oris. - The ring muscle of the mouth is also usually classed with the muscles of expression, as its action is to close the lips and press them against the teeth. It surrounds Fig. 72. - Muscles of Right Eyeball within the Orbit. Seen from the front. 21, superior rectus; 22, inferior rectus; 23, ex- ternal rectus; 24, internal rectus; 25, superior oblique; 26, inferior oblique. Fig. 73. - Muscles of Eyeball. Seen from side. 19, elevator muscle of eyelid ; 22-26, same as in Fig. 55. 94 ANATOMY FOR NURSES [Chap. VI Fig. 74. - Temporal and Deep Muscles about the Mouth. (Gerrish.) the opening of the mouth, extending from the nose above to the chin below, and constitutes a sphincter to the mouth. It is attached above to the partition between the nostrils and the upper jaw bones, and below to the mandible. Chief muscles of the tongue. - The chief muscles connecting the tongue and tongue bone to the lower jaw are the genioglossus and styloglossus. The genioglossus has its origin in the front part of the man- Fig. 75. Pterygoid Muscles. Viewed from behind, the back portion of the skull having been removed. (Gerrish.) STYLOID PROCESS Fig. 76.-Muscles of the Tongue. Viewed from the right side. (Gerrish.) 95 96 ANATOMY FOR NURSES [Chap. VI dible, and is inserted in the whole length of the tongue in and at the side of the mid line. The styloglossus has its origin in the styloid process of the tem- poral bone, and is inserted in the whole length of the side and under part of the tongue. They are interesting to us from the fact that during general anaesthesia they, together with the other muscles, become relaxed, and it is necessary to press the angle of the lower jaw upwards and forwards in order to prevent the tongue from falling back- wards and obstructing the larynx. Muscles of the neck. - The two superficial muscles of the neck are: 1. Platysma, 2. Sterno-cleido-mastoid. Platysma (broad sheet muscle).-It arises from the skin and areolar tissue covering the pectoral, deltoid, and trapezius muscles, and is inserted in the mandible and muscles about the angle of the mouth. It draws the angle of the mouth down and contracts the skin of the neck. Sterno-cleido-mastoid. - The most prominent muscle of the neck is the sterno-cleido-mastoid. It is named from its origin and insertion, arising from part of the sternum and clavicle, and being inserted into the mastoid portion of the temporal bone. This muscle is easily recognized in thin persons by its forming a cord-like prominence obliquely situated along each side of the neck. It flexes the head and rotates the face to the opposite side and serves as a convenient landmark in locating the great vessels carrying the blood to and from the head. If one of these muscles be either abnormally contracted or paralyzed, we get the deformity called wiy neck. CHIEF MUSCLES OF THE TRUNK They may be arranged in four groups: - 1. Muscles of the back. 2. Muscles of the chest. 3. Muscles of the thorax. 4. Muscles of the abdomen. Muscles of the back.-The muscles of the back are disposed in five layers, one beneath another. The two largest and most su- perficial muscles are: 1. The trapezius, 2. The latissimus dorsi. Chap. VI] MUSCULAR TISSUE 97 Trapezius. - The trapezius arises from the middle of the occipital bone, from the liga- mentum nuchae,1 and from the spinous processes of the last cervical and all the thoracic vertebrae. From this extended line of origin the fibres con- verge to their insertion in the acromion process and spine of the scapula. It is a very large muscle, and covers the other muscles of the upper part of the back and neck, also the upper portion of the latissimus dorsi. Latissimus dorsi. - The la- tissimus dorsi arises from the last six thoracic vertebrae, and through the medium of the lumbar aponeurosis, from the lumbar and sacral part of the spine and from the crest of the ilium. The fibres pass upwards and converge into a thick, nar- row band, which winds around and finally terminates in a flat tendon, which is inserted into the front of the humerus just below its head. These muscles act upon the bones of the upper extremity, and are often more properly reckoned as belonging to the muscles of that region. They elevate the shoulders, move the arms, and assist to draw the body up in climbing. Muscles of the chest. - The chief bulk of the anterior mus- cular wall of the chest is made up of the pectoral muscles. The pectoralis major arises from the sternal end of the clavicle, the sternum, and the six upper ribs. The fibres converging form a thick mass, which is inserted by a tendon of considerable breadth into the upper part of the humerus. The pectoralis minor is underneath and entirely covered by the major. As these muscles Fig. 77.-The Ligamentum Nuch/e. Seen from the right side. (Gerrish.) 1 The ligamentum nuchae is a form of ligament that stretches from the protuberance of the occiput to the spinous processes of the seven cervical vertebrae. 98 ANATOMY FOR NURSES [Chap. VI move the arm, they are, like the superficial muscles of the back, usually reckoned among the muscles of the upper extremity. Covering the pectoral muscles is a superficial fascia (composed LAST CERVICAL VERTEBRA INFRA- SPINATUS ^RHOMB. LAST THORACIC VERTEBRA LAST LUMBAR VERTEBRA Fig. 78. - Muscles in the Superficial Layer of the Back. (Gerrish.) of connective tissue) in'which are lodged the mammary glands and a variable amount of fat. Muscles of the thorax. - The muscles of the thorax are chiefly concerned with the movements of the ribs during respiration. They are the: 1. Intercostals, and 2. Levatores costarum. Intercostals.-The intercostals are found filling the spaces between the ribs. Each muscle consists of two layers, one ex- ternal and one internal, and as there are eleven intercostal spaces on each side, and two muscles in each space, it follows there are forty-four intercostal muscles. The fibres of these muscles run in opposite directions. The external fibres arise from the lower border of a rib, run downward, forward, and inward, and are inserted into the upper Fig. 79. - Front of Chest and Shoulder of Right Side, Superficial Muscles. (Gerrish.) INTERNAL INTERCOSTAL SEEN THROUGH ARTIFICIAL GAP IN EXTERNAL Fig. 80. - Intercostal Muscles in Right Wall of Thorax. (Gerrish.) 99 100 ANATOMY FOR NURSES [Chap. VI border of the next lower rib. Their action is to pull the ribs upward and outward, thereby increasing the chest cavity. The internal fibres arise from the lower border of a rib, run downward, outward, and backward, and are inserted into upper border of the next lower rib. Their action is to depress the ribs. Levatores costaruni (lifters of the ribs). -They arise from the transverse processes of the vertebras from the seventh cervical to the eleventh thoracic, and are inserted into the outer surface of the ribs between the tubercles and angles. They assist in eleva- tion of the first ten ribs, and with other muscles draw the lower ribs backward. Diaphragm. - The diaphragm is a thin, musculo-fibrous par- tition placed obliquely between the abdominal and thoracic Fig. 81.-Diaphragm. Viewed from in front. (Gerrish.) cavities. It is dome-shaped, and consists of muscle fibres arising from the whole of the internal circumference of the thorax, and of a central aponeurotic tendon, shaped somewhat like a trefoil leaf, into which the muscle fibres are inserted. It has Chap. VI] MUSCULAR TISSUE 101 three large openings for the passage of the aorta, the large artery of the body, the inferior vena cava, one of the largest veins of the body, and the oesophagus, or gullet; it has also some smaller openings, of less importance, for the passage of blood-vessels, nerves, etc. The upper or thoracic surface of the diaphragm is highly arched; the heart is supported by the central tendinous portion of the arch, the right and left lungs by the lateral portions, the right portion of the arch being slightly higher than the left. The lower or under surface of the diaphragm is deeply concave, and covers the liver, stomach, pancreas, spleen, and kidneys. The action of the diaphragm modifies considerably the size of the chest, and the position of the thoracic and abdominal viscera, and it is essentially the great respiratory muscle of the body. The mechanical act of respiration consists of two sets of movements; viz. those of inspiration and of expiration, in which air is successively drawn into the lungs and expelled from them by the alternate increase and diminution of the thoracic cavity. The changes in the capacity of the thorax are effected by the expansion and contraction of its lateral walls, called costal respiration, and by the depression and elevation of the floor of the cavity, through contraction and relaxation of the diaphragm, called diaphragmatic, or abdominal, respiration. These two movements are normally combined in the act of respiration, but in different circumstances one of them may be employed more than the other. Abdominal respiration predominates in men and in children, and costal respiration in women. In the act of inspiration the diaphragm contracts, and in contracting flattens out and descends, the abdominal viscera are pressed downwards, and the thorax is expanded vertically. In normal or quiet ex- piration the diminution of the capacity of the chest is mainly due to the return of the walls of the chest to the condition of rest, in consequence of their own elastic reaction and weight, and of the resiliency of the viscera displaced by inspiration. In more forcible acts of expiration, and in efforts of expulsion from the thoracic and abdominal cavities, all the muscles which tend to depress the ribs, and those which compress the abdominal cavity, concur in powerful action to empty the lungs, to fix the trunk, and to expel the contents of the abdominal viscera. Thus 102 ANATOMY FOR NURSES [Chap. VI the diaphragm is an expulsive as well as the chief respiratory muscle of the body. Muscles of the abdomen. - The muscular walls of the abdomen are mainly formed by three layers of muscles, the fibres of which run in different directions, those of the superficial and middle layers being oblique, and those of the innermost layer being trans- verse. In front, these three layers of muscles are replaced by tendinous expansions or aponeuroses, which meet in the middle line, the line of union giving rise to a white cord-like line, the linea alba. On each side of this line the fibres of a straight muscle, the rectus muscle, extend in a vertical direction between the tendinous layers. The abdominal muscles are covered and lined by sheets of fascia3, some of which are very dense and strong, and serve to strengthen weak points in the muscular walls. External oblique. - The strongest and most superficial of the abdominal muscles is the external oblique, the fibres of which, arising from the lower eight ribs, incline downwards and for- wards and terminate in the broad apo- neurosis, which, meeting its fellow of the opposite side in the linea alba, covers the whole of the front of the abdomen. The lowest fibres of the aponeurosis are gathered together in the shape of a thickened band, which extends from the anterior superior spinous process of the ilium to the pubic bone, and forms the well-known and important landmark, the inguinal ligament, more commonly known as Poupart's liga- ment from the anatomist who first described it. Just above this liga- ment, and near the pubic bone, is an oblique opening which transmits the spermatic cord in the male, or the round ligament in the female. This opening, called the external abdominal ring, is often the seat of hernia. (See Fig. 79 for external oblique.) Fig. 82. - Rectus Abdom- inis AND ObLIQUUS InTERNUS of Right Side. (Gerrish.) Chap. VI] MUSCULAR TISSUE 103 Internal oblique. - The internal oblique muscle lies just beneath the external oblique. It arises from the inguinal liga- ment, the outer crest of the ilium, and slightly from the lumbar fascia.1 Its most posterior fibres run upwards and forwards and are inserted in the costal cartilages of the four lower ribs. At the outer border of the rectus muscle the remaining muscle fibres expand into a broad aponeurosis. This aponeurosis divides into two layers, one passing before, the other behind, the rectus muscle; they reunite at its inner border in the linea alba, and thus form a sheath for the rectus, ex- tending from the xiphoid process to the crest of the pubis. At the lower part of the rectus the posterior layer of the aponeurosis is deficient. Rectus abdominis. - The rectus is a long, flat muscle, consisting of vertical fibres situated at the fore part of the abdomen, and enclosed in the fibrous sheath formed by the aponeurosis of the internal oblique. It arises from the pubic bone, and is inserted into the car- tilages of the fifth, sixth, and seventh ribs; it is separated from the muscle of the other side by a narrow interval which is occupied by the linea alba. Transversalis. -- The transversalis muscle lies beneath the internal ob- lique. The fibres arise from the lower six costal cartilages, the lumbar fascia, the crest of the ilium, and the outer third of the inguinal ligament. The greater part of its fibres have a hori- zontal direction, and are inserted in the linea alba and the crest of 'the pubes. Linea alba. - The linea alba, or white line, is a tendinous band formed by the union of the aponeuroses of the two Fig. 83. - Transversalis Abdominis of Right Side. (Gerrish.) 1 The lumbar fascia is really a combination of tendons that springs from the lumbar and sacral portions of the vertebral column. (See page 127.) 104 ANATOMY FOR NURSES [Chap. VI oblique and transverse muscles, the tendinous fibres crossing one another from side to side. It extends perpendicularly, in the middle line, from the xiphoid portion of the sternum to the pubis. It is a little broader above than below, and a little below the middle it is widened into a flat, circular space, in the centre of which is situated the cicatrix of the umbilicus. The abdominal muscles perform a threefold action. When acting from both pelvis and thorax as fixed points, they compress the abdominal viscera by constricting the cavity of the abdomen, in which action they are much assisted by the descent of the diaphragm. By these means they give assistance in expelling the foetus from the uterus, the faeces from the rectum, the urine from the bladder, and its contents from the stomach in vomiting. When the pelvis and spine are the fixed points, the abdominal muscles raise the diaphragm by pressing on the abdominal viscera, draw down the ribs, compress the lower part of the thorax, and assist in expira- tion. Again, if the trunk and arms are the fixed point, the muscles draw the pelvis upwards as a pre- paratory step to the elevation of the lower limbs in the action of climbing. MUSCLES OF THE UPPER EX- TREMITY A certain number of muscles sit- uated superficially on the trunk pass to the bones of the shoulder and of the arm, so as to attach the upper limbs to the trunk. Of these, the two superficial muscles we have mentioned as covering the back, the trapezius and latissimus dorsi, and the pectoral muscles covering the front of the chest, are the chief. The most promi- nent muscles found in the upper limbs are: - Fig. 84. - Muscles of the Front of the Right Shoulder and Arm. (Gerrish.) Chap. VI] MUSCULAR TISSUE 105 Deltoid. Biceps. Triceps. Pronators. Supinators. Flexors. Extensors. Deltoid. -The deltoid is a coarse, triangular muscle covering the top of the shoulder. It arises from the clavicle, acromion process and spine of the scapula, extends downwards, and is inserted into the middle of the shaft of the humerus. It raises the arm from the side so as to bring it at right angles to the trunk. Biceps. - The biceps is a long fusiform muscle, occupying the whole of the anterior surface of the arm; it is divided above Fig. 85. - Muscles on the Dorsum of the Right Shoulder and Arm (Gerrish.) into two portions or heads, from which circumstance it has received its name. It arises by these two heads from the scapula, and is inserted into the radius. It flexes the forearm on the arm. Triceps.-The triceps is situated on the back of the arm, 106 ANATOMY FOR NURSES [Chap. VI extending the whole length of the posterior surface of the hu- merus. It is of large size, and divided above into three heads; hence its name. It arises from the scapula and the posterior sur- face of the humerus, passes down- ward, all the heads uniting in a common tendon which is inserted into the ulna. It is the great extensor muscle of the forearm, and is the direct antagonist of the biceps. The muscles covering the fore- arm are disposed in groups, the pronators and flexors being placed on the front and inner part of the forearm, and the supinators and extensors on the outer side and back of the forearm: they antagonize one another. The pronators turn the palm of the hand backward and, when the elbow is flexed, downwards or prone. The supinators turn the palm of the hand forward, and, when the elbow is flexed, upwards or into the supine position. The flexors and extensors -have long tendons, some of which are in- serted into the bones of the wrist, and some into the bones of the fingers: they serve to flex and extend the wrist and fingers. The tendons of these muscles are held close to the bones of the wrist by the action of transverse bands of fasciae called annular ligaments. (See page 128, Chap- ter VII.) Fig. 86. - Muscles in the Dorsum of the Right Forearm and Hand. (Gerrish.) Chap. VI] MUSCULAR TISSUE 107 MUSCLES OF THE LOWER EXTREMITY These include the muscles of hip, thigh, leg, and foot. The most important of these are: - Glutei, or gluteal muscles. Psoas magnus. Posterior femoral. Anterior femoral. Internal femoral. Tibialis anterior. Extensors. Peroneal. Gastrocnemius. Soleus. Flexors. Tibialis posterior. If we compare the muscles of the shoulder, arm, and forearm with those of the hip, thigh, and leg, we shall see that the ante- rior muscles of the former correspond roughly with the poste- rior muscles of the latter, the muscles of the hip, thigh, and leg, however, being larger and coarser in texture than those of the shoulder, arm, and forearm. The glutei. - The glutei, or three gluteal muscles, form the chief prominence of the buttock. 1. Gluteus maximus arises from the ilium, sacrum, and coccyx, and is inserted into the great trochanter of the femur. Gluteus medius and gluteus minimus are under the gluteus maximus and al- most entirely covered by it. They are coarse in texture, and are largely concerned in supporting the trunk upon the head of the femur, and in bringing the body into the erect position when the trunk is bent forwards upon the thigh. Psoas magnus. - The great loin muscle arises from the last thoracic and all the lum- bar vertebrae with the included intervertebral cartilages. It extends down and forward, then down and backward, to its insertion in the small trochanter Fig. 87. - Gluteus Maximus of Right Side. (Gerrish.) 108 ANATOMY FOR NURSES [Chap. VI of the femur. Its action is flexion and external rotation of thigh. Fig. 88. - Psoas, Iliacus, and Obturator Externus Muscles. (Gerrish.) Posterior femoral.-The posterior femoral, or hamstring muscles, cover the back of the thigh. There are three of these muscles, - the biceps, the semitendinosus, and the semimem- branosus. The chief of these is the biceps, and is somewhat analogous to the biceps covering the front of the arm. The action of the hamstring muscles is to flex the knee and to extend the thigh. Anterior femoral.-The principal anterior femoral muscles are the quadriceps and the sartorius. Chap. VI] MUSCULAR TISSUE 109 Quadriceps. - The quadriceps is a four-headed muscle that covers the front of the thigh, and is analogous to the triceps covering the back of the arm. Each head is described as a Fig. 89.-Muscles in the Dorsum of the Right Thigh. (Gerrish.) Fig. 90. -Superficial Muscles in Front Part of the Right Thigh. (Gerrish.) separate muscle: 1. Rectus femoris, 2. Vastus externus, 3. Vastus internus, 4. Vastus intermedins. The rectus femoris arises from the ilium, the other three arise from the femur. They pass downward, and are inserted by 110 ANATOMY FOR NURSES [Chap. VI Fig. 91. - Vastus Intermedius of Right Side. (Gerrish.) one tendon to the tubercle of the tibia. The tendon passes in front of the knee-joint, and the patella is a sesamoid bone developed in it. The quadriceps is the great exten- sor of the leg; it also flexes the thigh, and antagonizes the action of the hamstring muscles. Sartorius. - The sartorius or tail- or's muscle, is a long, ribbon-like muscle, the longest in the body: it crosses the thigh obliquely from its origin in the ilium to its insertion in the tibia. It was formerly sup- posed to be the muscle principally concerned in producing the posture Fig. 92. - Gastrocnemius of Right Side. (Gerrish.) Chap. VI] MUSCULAR TISSUE 111 assumed by the tailor in sitting cross-legged, and hence its name. Internal femoral.-The internal femoral, or adductor mus- cles, occupy the internal portion of the thigh: they are all ad- ductors of the thigh. The tibialis anterior, the extensors, and the peroneal muscles cover the front and outer side of the leg. The gastrocnemius and the soleus, the flexors, and the tibialis posterior cover the back of the leg. The action of the tibialis anterior and of one of the three peroneal muscles (peroneus tertius) is to flex the ankle, while the action of the tibialis posterior and the other peroneal muscles (peroneus longus, peroneus brevis) is to extend the ankle. The flexors and extensors act on the toes. Gastrocnemius and soleus. - The gastrocnemius and soleus form the calf of the leg. The gastroc- nemius arises by two heads from the two condyles of the femur. The soleus is in front of the gastrocne- mius. It arises from the tibia and fibula. The direction of both is downward, and they are inserted into a common tendon, the tendon of the heel (tendo Achillis), which is the thickest and strongest tendon in the body, and is inserted into the calca- neum, or heel bone. The muscles of the calf possess considerable power, and are constantly called into use in standing, walking, dancing, and leap- ing; hence the large size they usually present. Fasciae. - Most of the muscles are covered closely by sheets of fibrous connective tissue called fasciae. (See Chapter VII.) RELATION OF MUSCLES TO NERVES The function of the muscles is to contract so that their two ends are drawn together, and a movement is thus produced which by various systems of levers can be converted into the particular form of motion required. For example, the con- Fig. 93. - Nerve ending in Muscular Fibre of a Lizard. (Kuhne.) The end-plate, or mo- torial ending of the axis cylinder is seen sideways. 112 ANATOMY FOR NURSES [Chap. VI traction of the muscles of the calf draws the heel upward, and in this way causes the whole body to be elevated on the toes. In order to bring about a muscular contraction the muscle must be stimulated. The way in which a muscle is normally stimulated is through its nerve, which conducts the nerve im- pulses from the central nervous system to the muscle fibres. Arriving at the latter, the nerve impulses bring about the complex chemical changes upon which the contraction of the muscle depends. When the nerve impulses cease, the muscle relaxes again. SUMMARY 1. Motion. 2. Forms fleshy part. 3. Assists in holding bones in place. Function . . 1. Irritability. 2. Contractility. 3. Tonicity. Special Properties Term used to describe influences which irritate or stimulate. Stimuli 1. Marked with longitudinal lines and trans- verse strife. 2. Under control of will. 3. Attached to bones. 4. Composed of bundles of fibres-Fasciculi. 5. Fibers composed of fibrillae. 6. Outer sheath of connective tissue - Epimy- sium. 7. Well supplied with nerves, blood-vessels, and lymphatics. 8. Contracts quickly. MUSCULAR TISSUE ' Voluntary t Skeletal Striated 1. Not marked with transverse strise. 2. Not under control of will. 3. Found in walls of blood-vessels and viscera. 4. Composed of elongated fibre-cells held to- gether by cement substance. 5. Outer sheath of connective tissue - Epimy- sium. 6. Well supplied with nerves, blood-vessels, and lymphatics. 7. Contracts slowly and continuously for long periods of time. Non- striated ' Involuntary , Visceral Striated, involuntary, visceral muscle. Con- tracts and relaxes quickly and unceasingly during life. Heart. . Chap. VI] MUSCULAR TISSUE 113 Name of Muscle and where found Origin Insertion Function Head Occipito-frontalis I ^clpit.A [ Frontal Superior rectus Inferior rectus Internal rectus External rectus Superior oblique Inferior oblique Levator palpebrse superioris Masseter Temporalis (temporal) Pterygoideus internus Pterygoideus externus Occipital bone Aponeurosis - top of skull Apex of orbit Apex of orbit Apex of orbit Apex of orbit Apex of orbit Orbital plate of maxilla Back of orbit. Sphenoid bone Zygomatic process of malar bone Temporal bone Sphenoid, palate, and maxilla Sphenoid bone Aponeurosis - top of skull Tissues of the eyebrows Upper and central portion of eyeball Lower and central portion of eyeball Midway on inner side of eyeball Midway on outer side of eyeball Eyeball - between superior and externa] recti Eyeball - near external recti Tarsus of upper lid Mandible Mandible Mandible Mandible fElevate the eyebrows, cause trans- j verse wrinkles of forehead. Draw [ scalp forward. Rolls the eyeball upward. Rolls the eyeball downward. Rolls the eyeball inward. Rolls the eyeball outward. Rolls the pupil downward and out- ward. Rolls the pupil upward and out- ward. Elevates upper lid and opens eye. Closes the mouth. Draws the man- dible forward. Closes the mouth. Draws the man- dible backward. Closes the mouth. Moves jaw for- ward and sideways. Moves the jaw forward and sideways. 114 ANATOMY FOR NURSES [Chap. VI Name of Muscle and where found Origin Insertion Function Head - Continued Buccinator Alveolar processes of max- illa and mandible Orbicularis oris Closes the mouth and keeps the food between the teeth. Orbicularis oris Partition between nostrils and maxilLe Mandible Closes the lips. Sphincter of mouth. Genioglossus Front part of mandible Whole length of tongue in and at the side of the mid line Thrusts the tongue forward. Styloglossus Styloid process of temporal bone Whole length of side' and under part of tongue Draws the tongue backward. Neck Platysma Skin and fascia of the pectoral, deltoid, and trapezius muscles Mandible and muscles about the angle of the mouth Draws the angle of the mouth and lower lip down and outward. Con- tracts the skin of the neck. Sterno-cleido-mastoideus Superficial layer of back Sternum and clavicle Mastoid portion of temporal bone Draw's the head toward the shoulder, rotates face toward opposite side. Trapezius Occipital bone,ligamentum nuchae, and spinous proc- esses of the last cervical and all the thoracic ver- tebrae Acromion process and spine of scapula Lifts the shoulder and rotates the lower angle of the scapula out- ward. Latissimus dorsi Last six thoracic vertebrae, lumbar, and sacral part of spine and crest of ilium Front of the humerus Elevates the shoulders, moves the arms, and assists to draw the body up in climbing. Chap. VI] MUSCULAR TISSUE 115 Name of Muscle and where found Origin Insertion Function Thorax Pectoralis major Clavicle, sternum, and car- tilages of six upper ribs Upper part of humerus Draws the arm inward and forward, and rotates it inward. Pectoralis minor Outer surfaces of 3d, 4th, and 5th ribs Scapula Draws the shoulder down and for- ward. Intercostales externi Arise from lower border of each rib Upper border of each lower rib Pull the ribs upward and outward. Intercostales interni Arise from lower border of each rib Upper border of each lower rib Depress the ribs. Levatores costarum Transverse processes of vertebrse from 7th cer- vical to the 11th thoracic Outer surface of the ribs be- tween the tubercles and angles Assist in elevation of the first ten ribs, and with other muscles draw the lower ribs backward. Aids in respiration. Diaphragm Internal circumference of the thorax A central aponeurotic ten- don Modifies size of chest cavity. Aids in expulsion. A bdomen Obliquus externus abdominis Lower eight ribs Outer lip of iliac crest, pubic spine and crest, the ilio- pectineal line, front of the symphysis and the linea alba Compression of abdominal viscera, rotation of the pelvis to the same side, and flexion of the pelvis on the chest. Obliquus internus abdominis Inguinal ligament, outer crest of the ilium, and the lumbar fascia Costal cartilages of four lower ribs, end of sternum, linea alba, and crest of pubes Compress the abdominal viscera, de- press the ribs, and flexes the chest upon the pelvis. 116 ANATOMY FOR NURSES [Chap. VI Name of Muscle and where found Origin Insertion Function Abdomen- Continued Rectus abdominis Pubic bone Costal cartilages of 5th, 6th, Depression of the thorax and com- Trans versalis Lower six costal cartilages, and 7th ribs Linea alba and crest of the pression of the abdominal viscera. Compression of the abdominal viscera. Upper Extremity Deltoideus lumbar fascia, crest of ilium, and outer third of the inguinal ligament Clavicle, acromion process, pubes Middle of shaft of humerus Raises the arm from the side. Biceps flexor cubiti and spine of scapula Scapula Radius Flexes the forearm on the arm. Triceps extensor cubiti Scapula and posterior sur- Ulna Extension of forearm. Pronator teres (front of face of the humerus Humerus and ulna Radius Pronation of the hand. nator forearm) Pronator quadratus (lower Inner and lower portion of Front and lower fourth of Pronation of the hand. p rC, quarter front of forearm, ulna radius rH . close to the bones) Flexor carpi radialis (front Humerus Base of 2d metacarpal bone Flexion and slight pronation of of forearm) Flexor palmaris longus Humerus on its palmar aspect Palmar fascia and anterior hand. Tightens the fascia of the palm, then <D (front of forearm) annular ligament flexes the hand. fR Flexor carpi ulnaris (front Humerus and ulna Pisiform, unciform, and base Flexion of the hand. and inner border of fore- arm) of 5th metacarpal Chap. VI] MUSCULAR TISSUE 117 Name of Muscle and where found Origin Insertion Function inators oper Extremity - Continued 'Brachio-radialis or long su- pinator (outer and front part of lower fourth of arm and forearm) Humerus Lower portion of radius Flexion of forearm and supination of hand. Extensors Sup Supinator brevis (deep in upper third of outer part . of forearm) 'Extensor carpi radialis longus (outer border of forearm) Extensor carpi radialis brevis (outer border of forearm) Extensor carpi ulnaris Lower Extremity External condyle of hu- merus Humerus Humerus Humerus and ulna Radius 2d metacarpal bone 3d metacarpal bone 5th metacarpal bone Supination. Extension of the hand. Extension of the hand. Extension of the hand. Gluteus maxim us Ilium, sacrum, and coccyx Great trochanter of femur Extension and external rotation of the thigh. Gluteus medius External surface of the ilium Great trochanter of femur Abduction of the thigh, and when the thigh is flexed, inward rotation. Gluteus minimus External surface of the ilium Great trochanter of femur Abduction of the thigh when it is extended, inward rotation when it is flexed. 118 ANATOMY FOR NURSES [Chap. VI Name of Muscle and where found Lower Extremity - Continued Psoas magnus (hind wall of abdomen and upper part of thigh) 3 Biceps flexor cruris | Semitendinosus SI Semimembranosus (Z) o Pm Quadriceps extensor cruris arises by four heads : - ci m o 1. Rectus femoris § 2. Vastus externus • 3. Vastus interims 4. Vastus intermedins <D •g Sartorius (front and inner side of thigh between . ilium and tibia) _ f Adductor magnus = g Adductor longus | Adductor brevis M [Adductor gracilis Origin Last thoracic and all the lumbar vertebrae with in- cluded intervertebral car- tilages Ischium and femur Ischium Ischium Ilium Femur F emur Femur Anterior superior iliac spine Pubic arch and ischium Pubic bone Upper part of pubic arch Lower part of pubic arch Insertion Small trochanter of femur Fibula and tibia Tibia Tibia Tibia Inner surface of the tibia Femur । Function Flexion and external rotation of thigh. Flexion of the leg, then external ro- tation. Extension of the thigh. Flexion of the leg, then external ro- tation. Extension of the thigh. Flexion of the leg, then external ro- tation. Extension of the thigh. Extends the leg and flexes the thigh. Flexion of the leg and thigh, abduc- tion of the thigh, then outward rotation. They all adduct the femur, rotating it outward, and draw the thighs together. Chap. VI] MUSCULAR TISSUE 119 Name of Muscle and where found Origin Insertion Function L rn ower Extremity - Continued 'Tibialis anterior (front and Tibia and interosseous Internal cuneiform and 1st Flexion of the foot and adduction of o outer side of leg) membrane metatarsal bone its distal end. Peroneus tertius (front of Fibula and interosseous 5th metatarsal bone Flexion of the foot and abduction of Ph leg, dorsum of foot) membrane its distal end. Tibialis posterior (back of Tibia and fibula Scaphoid, three cuneiform, Extension of the foot and abduction leg and inner part of foot) Peroneus longus (outer Tibia and fibula cuboid, 2d, 3d, and 4th metatarsal bones Base of 1st metatarsal and of its distal end. Extension of the foot and abduction co side of leg and sole of internal cuneiform bones of its distal end. 5 CO g foot) Peroneus brevis (outer Fibula 5th metatarsal bone Extension of the foot and abduction K side of leg and foot) Gastrocnemius Femur Tuberosity of the calcaneum of its distal end. Extension of the foot; also when the Soleus Fibula and tibia Tuberosity of the calcaneum ankle joint is flexed, flexion of the leg. Extension of the foot. CHAPTER VII SPECIAL MEMBRANES AND GLANDS MEMBRANE The word " membrane" is used to denote an enveloping or a lining tissue of the body. The chief membranes of the body are classified as follows: - 1. Serous. 2. Synovial. 3. Mucous. 4. Cutaneous. SEROUS MEMBRANES Serous membranes are thin, transparent, tolerably strong, and elastic. The surfaces are moistened by a fluid resembling serum, from which the membranes obtain their name of serous mem- branes. They consist of two layers only: - (1) Endothelium. (2) Corium. (1) Endothelium is the name given to a variety of epithelium found lining (i.e. lying within) certain parts of the body. It consists of a single layer of flattened transparent cells joined edge to edge so as to form a smooth membrane. (2) The corium consists of a thin layer of fibrous tissue, and contains blood-vessels, lymph-vessels, and lymphoid tissue. Serous membranes are found lining closed cavities and pas- sages that do not communicate with the exterior. They may be divided into four classes: - (1) Serous membranes proper. (2) The lining membrane of the vascular system. 120 Chap. VII] MEMBRANE 121 (3) The lining membrane of certain cavities. (4) The lining membrane of the cavity of the cerebro-spinal axis. Fig. 94. - Portion of Endothelium of Peritoneum, a, larger cells; b, smaller ones. (Klein.) (1) Serous membranes proper.-With one exception, these membranes form closed sacs, one part of which is attached to the walls of the cavity.which it lines, - the parietal portion, - whilst the other is reflected over the surface of the organ or organs con- tained in the cavity, and is named the visceral portion of the mem- brane. In this way the viscera are not contained within the sac, but are really placed outside of it, and some of the organs may receive a complete, while others receive only a partial, or scanty, investment.1 This class of serous membranes includes: - (a) The two pleurce, which cover the lungs and line the chest. (6) The pericardium, which covers the heart. 1 The inner surface of a serous membrane is free, smooth, and polished; the inner surface of one part is applied to the corresponding inner surface of some other part, a very small quantity of fluid only being interposed be- tween the surfaces. The organs situated in a cavity lined by a serous mem- brane, being themselves also covered by it, can thus glide easily against its walls or upon each other, their motions being rendered smoother by the lubricating fluid. 122 ANATOMY FOR NURSES [Chap. VII (c) The peritoneum 1 which lines the abdominal cavity and clothes its contained viscera. In passing from one part to another this membrane frequently forms folds, some of which are designated by special names, such as - Mesentery, the peritoneal attachment of the small intestines. Meso-colon, the peritoneal attachment of the colon. Omentum, a fold of the peritoneum connecting the abdominal viscera with the stomach. (2) The lining membrane of the vascular system. - This applies to the internal coat of the heart, blood-vessels, and lymphatics. It bears a close resemblance to the proper serous membranes in structure and appearance. (3) The lining membrane of certain cavities : - (a) One illustration of this is found in the internal ear. Around the membranous labyrinth, which is the essential por- tion of the organ of hearing, and between it and the bone in which it is lodged, is a space lined with serous membrane and filled with a fluid called perilymph. (6) Another example is the capsule of Tenon. This capsule is a shut sac placed back of the eyeball, with a visceral layer upon the globe of the eye, and the parietal layer attached to the bed of fat on.which the eyeball rests. (4) The lining membrane of the cavity of the cerebro-spinal axis.2 - The brain and spinal cord enclose cavities which are lined with a delicate serous membrane. One of the membranes that envelop the brain and spinal cord (arachnoid) is also a serous membrane. SYNOVIAL MEMBRANES The synovial membranes are composed entirely of connective tissue, with the usual cells and fibres of that tissue. They are distinguished by the nature of their secretion, which is a viscid, glairy fluid, resembling the white of an egg and named synovia. 1 The peritoneum in the female is the one exception to the rule that serous membranes are perfectly closed sacs, as it has two openings by which the uterine (Fallopian) tubes communicate with its cavity. 3 The cerebro-spinal axis or central nervous system consists of the brain and spinal cord. Chap. VII] MEMBRANE 123 From its nature, it is well adapted for diminishing friction, and thereby facilitating motion. They are' divided into the following classes: - 1. Articular. 2. Vaginal. 3. Bursal. 1. Articular. - Articular synovial membranes are found'sur- rounding and lubricating the cavities of the movable joints in which the opposed surfaces glide on each other. 2. Vaginal.-Vaginal synovial membranes are found forming sheaths for the tendons of some of the joints, and thus facilitating their motion as they glide in the fibrous sheaths which bind them down against the bones. (See Fig. 97.) 3. Bursal. - Bursal synovial membranes, or synovial bursse, are found in the form of simple sacs, interposed, so as to prevent fric- tion, between two surfaces which move upon each other. These bursae may be either deep-seated, or subcutaneous. The deep- seated are for the most part placed between a muscle and a bone, or between a tendon and a bone. The subcutaneous bursae lie immediately under the skin, and occur in various parts of the body, interposed between the skin and some firm promi- nence beneath it. The large bursa, situated over the patella,1- is a well-known example of this class, but similar, though smaller, bursae are found also over the olecranon, the malleoli, the knuckles, and other prominent parts. MUCOUS MEMBRANES The mucous membranes, unlike the serous membranes, line passages and cavities which communicate with the exterior. They are all subject to the contact of foreign substances intro- duced into the body, such as air and food, and also to the contact of secreted matters; hence their surface is coated over and pro- tected by mucus, from which it derives its name. Mucus is a thicker and more sticky fluid than the secretion which moistens the serous merpbranes. The mucous membranes of different parts are continuous, and they may nearly all be reduced to two great divisions; namely, (1) gastro-puhnonary and (2) the genito- urinary. 1 Enlargement and inflammation of this bursa is known as " Housemaid's knee." 124 ANATOMY FOR NURSES [Chap. VII (1) Gastro-pulmonary,- The gastro-pulmonary mu- cous membrane covers the inside of the alimentary canal, the air-passages, and the cavities communicat- ing with them. It com- mences at the edges of the lips and nostrils, proceeds through mouth and nose to the throat, and thence is continued throughout the entire length of the alimentary canal to the anus. At its origin and termination it is continu- ous with the external skin. It also extends throughout the windpipe, bronchial tubes, and air-sacs. From the interior of the nose the membrane may be said to be prolonged into the lac- rimal passages, and under the name of conjunctival membrane, over the fore part of the eyeball and in- side of the eyelids, on the edges of which it again meets with the skin. From the upper part of the pharynx a prolongation ex- tends on each side, along the passage to the ear; and offsets in the alimentary canal go to line the salivary, pancreatic, and biliary ducts, and the gall-bladder. (2) Genito-urinary. - The genito-urinary mucous UPPER LIP LOWER LIP DUCTS OF 5 SALIVARY \ GLANDS J Fig. 95. - Diagram of the Gastro-pul- monary Mucous Membrane, showing the Continuity of all its Parts. (Gerrish.) Chap. VII] MEMBRANE 125 membrane lines the inside of the bladder, and the whole uri- nary tract from the interior of the kidneys to the meatus uri- narius, or orifice of the urethra; it also lines the vagina, uterus, and uterine (Fallopian) tubes in the female. A mucous membrane is composed of a layer of connective tissue called the corium, which is bounded toward the free sur- face by a basement membrane and covered by a layer of epithe- lium. Beneath the corium we usually find a thin layer of mus- cular tissue called the muscularis mucosae. From the above, it will be seen that, starting at the free surface, the order of the tissues is as follows: - (1) Epithelium. (2) Basement membrane. (3) Corium. (4) Muscularis mucosae. (1) The epithelium is the most constant part of a mucous membrane, being continued over certain parts to which the other parts of the membrane cannot be traced. It may be scaly and stratified, as in the throat, columnar, as in the intestine, or cil- iated, as in the respiratory tract. (2) The basement membrane consists of a layer of flattened cells, and is really part of the corium. (3) The corium of a mucous membrane is composed of either areolar or lymphoid connective tissue. It is generally much thicker than in serous or synovial membranes, and varies much in structure in different parts. The lymphoid variety is in cer- tain places greatly increased in amount, packed with lymphoid cells, and forms the solitary lymph nodules and the aggregated lymph nodules of Peyer. (4) The muscularis mucosae consists, as previously stated, of a thin layer of muscular tissue. The mucous membranes are attached to the parts beneath them by areolar tissue, here named "submucous," and which differs greatly in quantity as well as in consistency in different parts. The connection is in some cases close and firm, as in the cavity of the nose. In other instances, especially in cavities subject to frequent variations in capacity, like the gullet and stomach, it is lax; and when the cavity is narrowed by contraction of its 126 ANATOMY FOR NURSES [Chap. VII outer coats, the mucous membrane is thrown into folds, or rugae, which disappear again when the cavity is distended. But in certain parts the mucous membrane forms permanent folds that cannot be effaced, and which project conspicuously into the cavity which it lines. The best-marked example of these folds is seen in the small intestine, where they are called circular folds (val- vulas conniventes), and which are doubtless provided for increasing- the amount of absorbing surface for the products of digestion. The redness of mucous membranes is due to their abundant supply of blood. The small blood-vessels which convey blood to the mucous membranes divide in the submucous tissue, and send smaller branches into the corium, where they form a net- work of capillaries just under the basement membrane. The lymphatics also form networks in the cori- um, and communicate with larger vessels in the submucous tissue below. The free sur- face of the mucous membrane is in some parts smooth, but in others is beset with little eminences called papillae and villi. Papillae. - The papillae are best seen on the tongue; they are small processes of the corium, mostly of a conical shape, contain- ing blood-vessels and nerves, and covered with epithelium. Villi. - The villi are most fully developed on the mucous coat of the small intestine. Being set close together like the pile of vel- vet, they give a shaggy or villous appearance to the membrane. They are little projec- tions of the mucous membrane, covered with epithelium, and containing blood- vessels and lacteals, and are favourably arranged for absorbing nutritive matters from the intestines. Fig. 96. - An Intes- tinal Villus, a, a, a, columnar epithelium ; b, b, capillary network ; d, lacteal vessel. CUTANEOUS MEMBRANE By this term is indicated the membrane which covers the body and is commonly spoken of as skin. It is a complex structure, and has several functions in addition to serving as a protective Chap. VII] MEMBRANE 127 covering for the deeper tissues lying beneath it. It will be more fully considered under the heading of Elimination. FASCIAE The word fascia means a band or bandage. It is applied to sheets of fibrous membrane which are wrapped around various organs, principally muscles, and serve to hold them in place. Fasciae are divided into two groups, which are associated*with the skin and the muscles. They are called: - 1. Superficial. 2. Deep. (1) Superficial fascia. - The subcutaneous areolar tissue, which forms a nearly continuous covering beneath the skin, is classed as superficial fascia. It is this web that contains the superficial fat. It covers the deep fascia and serves as a medium for the lodgment of vessels and nerves on their way to and from organs. It both connects and separates structures between which it is placed. It varies in thickness, and usually permits free movement of the skin on the subjacent parts. The palm of the hand (palmar fascia) and sole of the foot (plantar fascia) are exceptions to this rule. (2) Deep fasciae. - The deep fasciae are sheets of white, flexible fibrous tissue, employed to envelop and bind down the muscles, also to separate them into groups. The deep fasciae are classi- fied in groups, and such groups are named according to the parts of the body where they are found, viz.:-fasciae of the head, cervical fascia; thorax, thoracic fascia, etc. Individual fasciae are frequently given the name of the muscle which they envelop and bind down, viz.: - temporal fascia, pectoral fascia, deltoid fascia, etc. The lumbar fascia.-The lumbar fascia is really a combination of tendons, but serves as a fascia and springs from the vertebral column in three layers: - (1) Outer, or posterior. (2) Middle. (3) Inner, or anterior. (1) The outer layer begins at the spinous process of the lumbar and sacral vertebra?. It is attached above to the last rib, and below to the outer tip of the iliac crest and the ilio-lumbar ligament. 128 ANATOMY FOR NURSES [Chap. VII (2) rhe middle layer starts from the transverse processes of the lumbar vertebrae. (3) The inner layer starts from the front of the bases of the same processes. The fascia resulting from the combination of these three layers gives rise to the transversalis muscle. Annular ligaments. - In the vicinity of the larger joints, as at the wrist and ankle, parts of the deep fascia become blended into tight transverse bands, which serve to hold the tendons close to the bones. These bands are called annular ligaments. GLANDS A gland is a secreting organ, or an organ which abstracts from the blood certain materials and makes of them a new sub- stance. The secreting glands are of three kinds:- 1. Simple. 2. Compound. 3. Ductless. 1. Simple glands.-The simple glands are generally tubular or saccular cavities, the tube in the tubular variety being sometimes so long that it coils upon itself, as in the sweat glands of the skin; they all open upon the surface by a single duct. 2. Compound glands.-In the compound glands the cavities are subdivided into smaller tubular or saccular cavities, opening by small ducts into the main duct, which pours the secretion upon the surface. 3. Ductless glands.-This term is applied to a collection of glandular structures that possess no ducts. They are well supplied with blood-vessels and lymphatics, and whatever secre- tion or excretion they produce is carried in these vessels. (See Chapter XII, page 211J Fig. 97. - The Ante- rior Annular Ligament of the Ankle and the Synovial Membranes of the Tendons beneath it. Artificially distended. (Gerrish.) Chap. VII] MEMBRANE 129 A secretory apparatus consists essentially of a layer of secreting cells placed in close communication with a network of blood- vessels. The simplest form in which a secretory apparatus Fig. 98. - Diagram showing Various Forms of Secreting Glands. 1, gen- eral plan of a secreting membrane ; a, epithelial cells ; b, basement membrane ; c, connective tissue in which lie the blood-vessels (d); 2-7, simple and compound tubular and saccular glands ; d, duct. occurs is in the shape of a plain, smooth surface, composed of a single layer of epithelial cells, resting usually on a thin mem- brane, on the under surface of which is spread out a close net- work of blood-vessels. In order to economize space and to provide a more extensive secreting surface, the membrane is generally increased by dipping down and forming variously 130 ANATOMY FOR NURSES [Chap. VII shaped depressions or recesses, these depressions or recesses being called the secreting glands. However simple or complicated the involuted surface, the secreting process is essentially the same; and in this process the nucleated cells play the most important part. These cells take into their interior those substances from the blood which they require to make the special secretion they are set apart to form, converting this selected material into chemical com- pounds, which either act as solvents, as in the digestive juices, or perform some other office in the body. The secretions the cells elaborate escapes from them either by exudation or by the bursting and destruction of the cells themselves. Cells filled with secreting matter may also be detached and carried out entire with the fluid part of the secretion; and, in all cases, new cells speedily take the place of those which have served their office. The glands are provided with lymphatics, and fine nerve fibrils have also been found to terminate in them. That they are under the influence of the nervous system is shown by the fact that impressions made on the nervous system affect the secretions, a familiar instance of which is the flow of saliva into the mouth, caused by the sight, or smell, or even thought, of food. SECRETION A new substance, the product of a gland, elaborated from the blood by cell action, and poured out upon the ex- ternal or internal surfaces of the body, is called a secretion. For purposes of study we may divide the secretions into two groups: - (1) External secretions. (2) Internal secretions. External secretions. - This term is used to designate those secretions of glandular tissues which are carried off to the exterior by a duct. All of the digestive juices - saliva, gastric juice, pancreatic juice, bile, and intestinal juice - are examples of external secretions because they are carried off from the respective glands in which they are formed by means of ducts. (See table of external secretions at end of Summary.) Chap. VII] MEMBRANE 131 Internal secretions. - This term is used to designate those secretions of glandular tissues which are not carried off to the exterior by a duct, but instead are discharged into the blood or lymph. The conception is that probably all the ductless glands form secretions which have a profound influence on nutritive changes in the body. Such secretions are called internal secre- tions. Experience has also shown that not only the ductless glands, but some at least of the typical glands provided with ducts, may give rise to internal secretions. For example, the pancreas forms pancreatic juice and discharges it by means of a duct into the small intestine. In addition, it is believed that the pancreas forms an internal secretion which passes into the blood. Excretion. - An excretion resembles a secretion, except that whereas the secretion is formed to perform some office in the body, the excretion is formed only to be thrown out of the body. Example - urine. SUMMARY Membrane - An enveloping or lining substance. MEMBRANE Varieties . 1. Serous membranes. 2. Synovial membranes. 3. Mucous membranes. 4. Cutaneous membranes. Serous Membranes -line closed cavities or passages that do not commu- nicate with the exterior. They are moistened by serum. Serous Membranes consist of Endothelium - lining corium. SEROUS MEMBRANES rPleurae (lungs). Pericardium (heart). Peritoneum (abdominal organs). Serous membranes proper Four Classes of Serous Membranes Heart. Blood-vessels. Lining membrane of vascular system Lymphatics. Internal ear. Back of eye. Lining membrane of certain cavities Lining membrane of the cavity of the cerebro-spinal axis. 132 ANATOMY FOR NURSES [Chap. VII SYNOVIAL MEMBRANES Synovial Membranes consist of connective tissue and secrete synovia. Articular synovial membranes Surround cavities of movable joints. Three Classes of Synovial Membranes Vaginal synovial membranes Form sheaths for ten- dons. Sacs interposed be- tween two surfaces which move upon each other. Bursal synovial membranes Mucous Membranes - line passages that communicate with the exterior' and are protected by mucus. Are well supplied with blood. ' Alimentary canal. Air-passages. Cavities communicating with both L alimentary canal and air-passages. Two Divisions of Mucous Membranes G astro-puhn on ary MUCOUS MEMBRANES Genito-urinary Urinary tract. Generative organs. 1. Epithelium. 2. Basement membrane. Mucous Membranes consist of 3. Corium Areolar tissue, or Lymphoid tissue. 4. Muscularis mucosae - thin layer of muscular tissue. Rugae - a wrinkle, or crease f (Esophagus. [ Stomach. Circular folds - permanent folds of mucous membrane found in small intestine. Papillae - conical processes of mucous membrane best seen on tongue. Contain blood-vessels and nerves. Villi - tiny teat-like projections of the mucous mem- brane of small intestine. Modifications of Mucous Membrane Fasciae - sheets of fibrous membrane which are wrapped around various organs, principally muscles. FASCIA Superficial Subcutaneous areolar tissue which covers the deep fascia. Two Groups . Deep - envelop and bind down muscles. Annular Ligaments - ring-like ligaments found in the vicinity of large joints. Serve to hold tendons close to bones. Glands - are organs that form secretions. GLANDS Varieties . . 1. Simple - have only one duct. 2. Compound - have many ducts. 3. Ductless-possess no duct. Chap. VII] MEMBRANE 133 Secretions - are substances elaborated from the blood by the glands. They are intended to perform some office in the body. SECRETIONS External secretions-are substances formed by the sim- ple and compound glands and discharged by means of a duct. Internal secretions - are substances formed by any kind of gland and discharged into the blood or lymph. Varieties . Excretions - are waste substances TABLE OF EXTERNAL SECRETIONS AND EXCRETIONS Secretion Secreting Organs Reaction Main Purpose Sebum Sebaceous glands of the skin Acid To oil the skin. Mucus Mucous cells of mucous mem- brane Alkaline Lubricant and diluent. Serous secretion Serous mem- bra n e s Alkaline Lubricant and diluent. Tears Lacrimal glands Alkaline To moisten conjunctivas. Saliva Salivary glands Alkaline To moisten food and digest car- bohydrates. Gastric Stomach Acid To digest proteids. juice Succus entericus Intestines Alkaline To dilute the chyme. Pancreatic juice Pancreas Alkaline To digest proteids, fats, and car- bohydrates. Bile Liver Alkaline Part of the bile is used in diges- tion and reabsorbed. Part is a true excretion (bile pigments). Milk Mammary glands Alkaline Food. Sweat Sweat-glands of skin Acid Elimination of water, carbon dioxide, and urea. Regulates body-temperature. Urine Kidneys Acid Elimination of water and urea. CHAPTER VIII THE VASCULAR SYSTEM; THE BLOOD Having studied three of the distinctive tissues of the body (the epithelial, connective, and muscular), their structure, posi- tion in the body, and the various functions they are especially adapted to perform, we shall next consider the vascular, respira- tory, alimentary, and excretory systems, by means of which all the tissues are supplied with the materials necessary for their life and growth, and relieved of all those waste and superfluous matters which are the results of their activity.1 THE BLOOD The most striking external feature of the blood is its well- known colour, which is bright red, approaching to scarlet in the arteries, but of a dark red or crimson tint in the veins. It is a somewhat sticky liquid, a little heavier than water; its specific gravity varies from 1.041 to 1.067. It has a peculiar odour, a saltish taste, a slight alkaline reaction, and a temperature of about 100° F. (37.8° C.). Quantity of blood. - The quantity of blood contained in the body is a balance struck between the tissues which give to, and those which take away from, the blood. Thus, the tissues of the alimentary canal largely add to the blood water and the material derived from the food, while the excretory organs largely take away water and the other substances constituting the excretions. From the result of a few observations on exe- cuted criminals, it has been concluded that the total quantity of blood in the human body is about yg of the body weight. 1 As the nervous tissue is the most highly organized of the tissues, and its functions are very complex and difficult to understand, the consideration of it is deferred until the student has mastered the vascular, respiratory, ali- mentary, and excretory systems. 134 Chap. VIII] THE VASCULAR SYSTEM 135 This, in an individual weighing 130 pounds, would weigh about 10 pounds, or measure 5 quarts. Functions of the blood. - Blood is commonly spoken of as the nutritive fluid of the body. This is quite correct, but it is more than a nutritive fluid,' as will be seen from the following list of its more important functions: - (1) It carries to the tissues the nutritive substances resulting from digestion. (2) It carries to the tissues oxygen, absorbed from the air in the lungs. (3) It carries from the tissues various waste products. (4) It serves as a medium for the transmission of certain internal secretions. (5) It aids in equalizing the temperature of the body. (6) It aids in equalizing the water contents of the body. (Howell.) Composition of the blood. - Seen with the naked eye, the blood appears opaque and homogeneous; but when examined with a microscope, it is seen to consist of a transparent, slightly yellowish fluid, with minute solid particles immersed in it. Plasma is the name given to the yellowish fluid. Corpuscles is the name given the solid particles. These corpuscles are of three kinds: - (1) Red or coloured. (2) White or colourless. (3) Blood-plates. Corpuscles. - These corpuscles exist in large numbers. In a cubic millimetre of healthy blood there are on an average 5,000,000 red corpuscles, 7000 white, and 500,000 blood-plates. The number of white varies much more than that of the red; the proportion of white to the red is usually given at from 1 to 250 up to 1 to 1000. The number of blood-plates is usually about the number of red corpuscles. Red corpuscles of the blood. - The red corpuscles have a nearly circular outline like a piece of coin, and most of them have a shallow, dimple-like depression on both sides; their shape is, therefore, that of biconcave circular disks. The average size is gdo o an (0-008 mm.) in diameter, and about 136 ANATOMY FOR NURSES [Chap. VIII (0.002 mm.) of an inch in thickness. Because of their extremely small size, the red corpuscles do not appear red when viewed singly with a microscope, but merely of a reddish yellow tinge, or yellowish green in venous blood. It is only when millions of them are gathered together that a distinct red colour is pro- duced. When blood is drawn from the vessels, the red disks sink in the plasma: they have a singular tendency to run together, and to cohere by their broad surfaces, so as to form cylindrical columns like piles or rouleaux1 of coins, and the piles join themselves together in an irregular network. Each red corpuscle is composed of a colourless elastic envelope and coloured fluid contents. The envelope is a very delicate membrane of a fatty nature, and may be ruptured or dissolved under certain condi- tions. The colour is due to the amount of oxygen contained in the blood in combination with the haemoglobin.2 If water be added to a preparation of blood under the micro- scope, the water passes into the corpuscle, and the concave sides of the corpuscle become bulged out so that it is rendered globular. By the further action of water the haemoglobin is dissolved out of the corpuscles, and the colourless envelope Fig. 99. - Red and White Corpuscles of the Blood. Magnified. A, moderately magni- fied, the red corpuscles are seen in rouleaux ; a, a, white corpuscles ; B, C, D, red corpuscles, highly magnified, seen in different positions ; E, a red corpuscle swollen into a sphere by imbibition of water ; F, G, white corpuscles, highly magnified ; K, white corpuscle treated with acetic acid ; H, I, red corpuscles wrinkled or crenated. 1 This tendency becomes marked in certain inflammatory conditions of the system, and to prevent it, injections of normal saline solution are often used. 2 Haemoglobin is a compound proteid, i.e. its molecules consist of a pro- teid portion and of a pigment portion, the latter containing one atom of iron. Chap. VIII] THE VASCULAR SYSTEM 137 remains as a faint circular outline or shadow corpuscle. Blood in which the haemoglobin has escaped out of the corpuscles into the plasma is known as laked blood. On the other hand, the addition of salt to a preparation of blood by absorbing the water causes the corpuscles to shrink, and become wrinkled or cre- natecl. They are very soft, flexible, and elastic, so that they readily squeeze through apertures and passages narrower than their own diameters, and immediately resume their proper shape. Function of the red corpuscles. - The red corpuscles, or erythrocytes, by virtue of the haemoglobin which they contain, are emphatically oxygen carriers. Exposed to the air in the lungs, the haemoglobin combines with the oxygen present in the air; this oxygen the haemoglobin carries to the tissues; these, more greedy of oxygen than haemoglobin itself, rob it of its charge, and the haemoglobin, thus deprived of its oxygen, hurries back to the lungs for a fresh supply.1 The utility of the haemo- globin consists in the ease with which, under certain conditions (those existing in the capillaries), it gives up this oxygen again. The colour of the blood is dependent upon this combination of the haemoglobin with oxygen; when the haemoglobin has its full complement of oxygen, the blood has a bright red hue; when the amount is decreased, it changes to a dark crimson hue. The scarlet blood is usually found in the arteries, and is called arterial; the dark crimson in the veins, and is called venous blood. The only other function of red corpuscles is a passive ability to pass through the capillary walls. This is called diapedesis. A microscopical examination of red corpuscles frequently shows small transparent spots, termed "pseudo-vacuoles." In them small parasites may be developed. When affected by malaria, the plasmodium malariae are developed in the pseudo-vacuoles of the red corpuscles. There is a constant destruction and renewal of the red cor- puscles. When the activity of a red corpuscle ceases, it dies, and is replaced by a new corpuscle developed in the bone marrow. White corpuscles of the blood.-The white, colourless cor- puscles are few in number compared with the red, and both on this account, and because of their want of colour, they are not 1 Haemoglobin rich with oxygen is called oxyhaemoglobin. When the oxygen is removed, it is called reduced haemoglobin. 138 ANATOMY FOR NURSES [Chap. VIII at first easily recognized in a microscopic preparation of blood. Their form is very various, but when they are carried along in the blood current, or when the blood is first drawn they are rounded or spheroidal. Measured in this condition, they are about ^koo an inch (0-010 mm.) in diameter. The white corpuscle may be taken as the type of a free animal cell. It is a small piece of protoplasm, containing a nucleus (sometimes two or even three nuclei), and has no limiting membrane or cell-wall (vide Fig. 99). Amoeboid movements. - These corpuscles, or cells, possess the power of spontaneous movement, and are capable of chang- ing their form and place. While, when in a state of rest, they assume in general the spheroidal form, we find that when they become active they send out variously shaped processes, some fine and delicate, others broad, and of very irregular shape. We often see, after a process has been thrown out, that it be- comes larger and larger, the cell-body becoming correspondingly smaller, until finally the whole cell passes over into the process, thus moving forward. These amoeboid movements are always very slow, and are greatly influenced by the temperature, density, and amount of oxygen in the fluid in which the cells lie. By virtue of this locomotive power the white blood-cells perform certain evolutions within the blood-vessels; they also escape through their walls, and sometimes singly, sometimes in vast numbers, move through the lymph spaces in the surrounding tissues. White blood corpuscles differ in many respects from the red: - (1) Size, colour, and appearance. (2) During circulation they keep close to and even seem to adhere to the walls of the vessels, while the red corpuscles keep in the middle of the stream. (3) They are found in lymph, chyle, pus, and other fluids, as well as in blood. Varieties. - At least five varieties have been studied and described. They are classified under two main heads: - (1) Leucocytes. (2) Lymphocytes. The most marked difference is in the nuclei and in the amount Chap. VIII] THE VASCULAR SYSTEM 139 of amoeboid movement exhibited. The difference is due solely to the age of the corpuscle - the lymphocyte being the more recently formed, and in time will change into a leucocyte. Function of the white corpuscles. - It is definitely known that they act as (1) protective agents, and (2) assist in coagulation of blood. Their function of protection is the most important, and is accomplished in two ways: - (a) By generating a defensive proteid which when imbibed by bacteria, kills them; (b) by virtue of their amoeboid move- ments they can creep around bacteria, envelop them with their own substance, and so put them inside themselves. This process is called phagocytosis, and has earned for them the name of phagocytes. Opsonins. - A name given to chemical substances found in blood plasma. The function of an opsonin is to prepare certain disease germs for destruction and absorption by the white cor- puscles of the blood. The phagocytic properties of the leuco- cytes becomes especially developed as the result of the action of opsonins. The presence of bacteria in any part of the body means that the leucocytes accumulate in that particular part, and a death struggle between the leucocytes and bacteria takes place. If the leucocytes are victorious, they not only kill the bacteria but remove every vestige of the struggle, and find their way back to the blood. If the bacteria are victorious, and suppuration ensues, the leucocytes become pus corpuscles. Also, in the case of a wound, the leucocytes, by virtue of their amoeboid movements, escape from the blood-vessels, accumulate in the region of the wound, and act as barriers against infection. Large numbers are lost in the battle waged against bacteria, others by hem- orrhage, and others may be converted into granulation tissue. These lost leucocytes are replaced by new leucocytes which result from the division of former leucocytes. This birth usu- ally takes place in the lymph nodes. Blood-plates. - They are small, pale yellow, or colourless disks of which little is known. They vary-in size and shape, but are always smaller than the red corpuscles. It is not de- cided whether they are to be considered as independent cells or as fragments of disintegrated cells. 140 ANATOMY FOR NURSES [Chap. VIII Plasma. - The plasma of the blood is of a clear, slightly yel- lowish colour. It consists for the most part of water charged with nutritive matter derived from our food, and waste matter derived from the tissues. In other words, it consists of water holding in solution or suspension: - (1) Proteid substances. (2) Various extractives. (3) Salts. (4) Fats and sugar. (5) Gases. The proteid substances are: - (a) Serum-albumin. (b) Para-globulin.1 (c) Fibrinogen. The serum-albumin and para-globulin occur in about equal quantities; but the fibrinogen, though a most important element in the blood, occurs in very small quantities. Serum-albumin holds the first place in regard to nutrition. It represents the proteid portion of our food supply and the greater part of the material necessary for the daily nourishment and renovation of the tissues. In this process it undergoes a variety of transformations, by which it is converted into the structural characteristics of the tissues which it supplies. Para-globulin belongs to the class of globulins. The origin and function are undecided. It may be a source of nitroge- nous food, and assists in coagulation of the blood. Fibrinogen belongs to the class of globulins, and is the sub- stance which produces the fibrin of coagulated blood. It is very difficult to obtain in the fluid condition, owing to the rapidity with which it solidifies when blood is withdrawn from the cir- culation. Extractives are substances other than proteids that may be extracted by special methods. Some of them represent waste products, such as urea, lecithin, and cholesterin. Salts in the plasma are the chlorides, carbonates, sulphates, and phosphates. Of the mineral salts the sodium chloride is 1 Sometimes called serum-globulin. Chap. VIII] THE VASCULAR SYSTEM 141 the most abundant, constituting nearly 40 per cent of all the saline ingredients. The mineral salts maintain the alkalinity of the blood, a property which is essential to nutrition, and even to the immediate continuance of life, since it enables the plasma to take up the carbon dioxide from the tissues and return it to the lungs for elimination. Fats and grape sugar are scanty except after a meal and in certain diseased conditions. Gases. - Oxygen, nitrogen, and carbon dioxide gas are found in the blood. Carbon dioxide is the result of oxidation in the tissues, and is found in both arterial and venous bloody but the quantity is greater in venous blood. THE CLOTTING OF BLOOD Blood when drawn from the blood-vessels of a living body is perfectly fluid. In a short time it becomes viscid, and this vis- cidity increases rapidly until the whole mass of blood becomes a complete jelly. If the blood in this jelly stage be left un- touched in a glass vessel, a few drops of an almost colourless fluid soon make their ap- pearance on the surface of the jelly. In- creasing in number and running together, the drops after a while form a superficial layer of pale straw-coloured fluid. Later on, similar layers of the same fluid are seen at the sides, and finally at the bottom of the jelly, which, shrunk to a smaller size and of firmer consistency, now forms a clot, or crassamentum, floating in a liquid. The upper surface of the clot is generally slight- ly concave. If a portion of the clot be ex- amined under the microscope, it is seen to consist of a network of fine fibrils, in the meshes of which are entangled the red and white corpuscles of the blood. The fibrils are composed of the fibrin; and the liquid Fig. 100. - Bowl of Recently Coagulated Blood, showing the Whole Mass Uniform- ly Solidified. (Col- lins.) Fig. 101. - Bowl of Coagulated Blood after Twelve Hours, SHOWING THE CLOT CON- TRACTED and Floating in the Fluid Serum. (Collins.) 142 ANATOMY FOR NURSES [Chap. VIII in which the clot is suspended is blood minus corpuscles and fibrin, and is called serum. The clotting of the blood is largely dependent upon the fibrin; for if fresh blood, before it has time to clot, be whipped with a bundle of twigs, the fibrin will form on the twigs, and if the whipping of the blood be continued until after the fibrin has been deposited on the twigs, the blood left in the vessel will be found to have lost the power of clotting. Such blood is called defibrinated. Conditions affecting coagulation. - Coagulation is hastened by - (1) Moderate temperature, 100-120° F. (2) Contact with any rough surface. (3) Contact with non-living matter. (4) Access of air. (5) Rest. Coagulation is hindered by - (1) A very high or a very low temperature. (2) Contact with living tissues, especially blood-vessels. (3) Absence of air.1 (4) Addition of neutral salts. (5) Contact with oil. After death, the blood usually remains a long time fluid in the vessels, and it never clots so firmly and completely as when shed. It clots first in the larger vesse1s, but not until several hours after death in the smaller vessels. Value of coagulation. - This property is of very great im- portance in the arrest of hemorrhage. The clot formed closes the openings of wounded vessels. The coagulability of the blood differs in different individuals, and in rare cases is so slight that the most trivial operation in- volving hemorrhage is attended with great danger. This con- dition is known as hemorrhagic diathesis or hemophilia. General composition of the blood. - Not only do the several tissues take up from the blood and give up to the blood different things at different rates and at different times, but all the tissues take up oxygen and give up carbon dioxide in varying quantities. From this it follows, on the one hand, that the composition and 1 When death results from asphyxiation, the blood remains fluid. Chap. VIII] THE VASCULAR SYSTEM 143 character of the blood most be forever varying in different parts of the body; and, on the other hand, that the united action of all the tissues must tend to establish and maintain an average uniform composition of the whole mass of blood. Note. - When we remember that the tissues live on the blood, we recognize the gravity of those diseased conditions in which important elements are being constantly drained away from the blood, as, for ex- ample, the albumin in diseases of the kidneys, the red corpuscles in hem- orrhage, the water of the blood in cholera, etc. Withdrawal of oxygen, as we all know, causes instant death, and a constant supply of fresh air is a vital necessity of life. Nor is it of less importance that the blood be kept free from those waste matters, - preeminently carbon dioxide and urea, - which, in accumulating, poison the system, and, if not excreted in sufficient amount, will as surely cause death as the withdrawal from the blood of any of its vital constituents. 144 ANATOMY FOR NURSES [Chap. VIII SUMMARY Colour . . . ' Bright red in arteries. Dark red in veins. Sticky fluid. Specific gravity, 1041 to 1067. Alkaline reaction. Temperature, 100° F. Peculiar odour. Salty taste. iV °f the body weight. Description . ■Carries internal secretions to and from different parts of body. Carries nutritive substances to tissues. Carries oxygen to tissues. Carries waste products from tissues. Aids in equalizing temperature. .Aids in equalizing water contents of body. BLOOD Functions . . Corpuscles (minute, solid particles) 1. Red or erythrocytes. 2. White, of which there are a num- ber of different kinds. 3. Blood-plates. Composition . Plasma - transparent, slightly yellowish fluid. Biconcave disks 3-2^5 in- in diameter, io- in thickness. Colourless elastic envelope and coloured fluid con- tents. Red Corpuscles Colour due to oxygen in combination with haemo- globin. Originate in bone marrow Function . Oxygen carriers. Diapedesis. Protoplasm. Nucleus (sometimes two or three nuclei). Amoeboid movement. CORPUSCLES Animal cell Description Round or spheroidal -when circulating in blood, in. in diameter. 1-250 red up to 1-1000 red. Originate in lymph nodes. White Corpuscles Lymphocytes Classified according to difference in nuclei and amount of amoeboid movement. Difference due to age. Classification Leucocytes Generate protective proteids. Scavengers - phagocytosis. Barriers against infection. Function Protective agents Assist in coagulation of blood. Chap. VIII] THE VASCULAR SYSTEM 145 CORPUSCLES Opsonins - Chemical substances that prepare disease germs for de- struction and absorption by the phagocytes. Pale yellow or colourless disks. Size and shape various; always smaller than red corpuscles and about the number of red. Blood-Plates 'Water. Proteid substances. Extractives. Salts. Fats and sugars. Gases. Composition Serum-albumin represents the proteid portion of our food supply. Para-globulin assists in coagulation of blood. Fibrinogen produces the fibrin of coagulated blood. Proteid Substances PLASMA Fats derived from food supply. Sugar. Extractives Urea Lecithin Cholesterin h Waste products, Chlorides. Carbonates. Sulphates. Phosphates. Salts . Oxygen obtained from air. Nitrogen obtained from air. Carbon dioxide result of oxidation. Gases . ' Water. Mineral salts. . Albumin. Description Serum Clot ' Fibrin formed from fibrinogen. Corpuscles, red and white. Defibrinated Blood - Blood from which fibrin has been removed. COAGULATION 'Moderate temperature, 100-120° F. Contact with any rough surface. Contact with non-living matter. Access of air. .Best. Hastened by. . A very high or a very low temperature. Contact with living tissues, especially blood-vessels Absence of air. Addition of neutral salts. Contact with oil. Hindered by. . Value - Checks hemorrhage. Hemophilia - Lack of coagulability of the blood. CHAPTER IX THE VASCULAR SYSTEM CONTINUED: HEART; ARTERIES; CAPILLARIES; VEINS The blood, as we have said, is the internal medium on which the tissues live. It is carried through the body by branched tubes named blood-vessels. It is driven along these tubes by the action of the heart, which is a hollow muscular organ placed in the centre of the vascular system. One set of vessels - the arteries - conducts the blood out from the heart and distributes it to the different parts of the body, whilst other vessels - the veins - bring it back to the heart again. The blood from the arteries gets into the veins by passing through a network of fine tubes which connect the two, and which are named, on account of their small size, the capillary (i.e. hair-like) vessels. All the tissues, with the exception of the cartilages, hair, nails, cuticle, and cornea of the eye,1 are traversed by these networks of capillary vessels. It is through the thin walls of the capillaries that the interchange of material which is continually going on between the blood and the tissues takes place. It is in the capillaries, then, that the chief work of the blood is done; and the object of the vascular mechanism is to cause the blood to flow through these vessels in the manner best adapted for accom- plishing this work. (1) The heart pumps the blood through the arteries into the capillaries, and from the capillaries back along the veins to itself again. (2) Arteries carry and regulate the supply of blood from the heart to the capillaries. (3) Capillaries receive blood from the smallest arteries (arteri- oles) and cany it to the smallest veins. 1 These parts not penetrated by the blood-vessels imbibe nutritive matter from adjacent tissues, and are just as dependent on the blood as all the other tissues. 146 Chap. IX] THE VASCULAR SYSTEM 147 (4) Veins carry the blood from the capillaries back to the heart. We shall see that the structure of these several parts is adapted to these several uses. THE HEART The heart is a hollow, muscular organ, situated in the thorax between the lungs, behind the sternum, and above the central depression of the diaphragm. It is about the size of the closed fist, shaped like a blunt cone, and so suspended by the great vessels that the broader end or base is directed upwards, back- wards, and to the right. The pointed end or apex points down- Fig. 102. - Heart in situ (Dalton, in Flint, "On the Heart "). a, b, c, d, e, ribs; 1, 2, 3, 4, 5, intercostal spaces; vertical line, median line; triangle, superficial cardiac region; X on the fourth rib, nipple. wards, forwards, and to the left. The impulse of the heart against the chest wall is felt in the space between the fifth and sixth ribs, a little below and to the inner side of the left nipple. As placed in the body, it has a very oblique position, and the right side is almost in front of the left. Myocardium. - The main substance of the heart is composed of muscular tissue and is called myocardium. It differs from 148 ANATOMY FOR NURSES [Chap. IX all other involuntary muscular tissue in possessing transverse striae. Fig. 103. - The Pulmonary Artery and Aorta. The front part of the right lung has been removed, and the pulmonary vessels and the bronchial tubes are thus exposed. (Gerrish.) The arrangement of the fibres is very intricate; they run transversely, longitudinally, obliquely, and in the apex take a spiral turn or twist. Between the muscle fibres is a certain amount of interstitial tissue, with numerous blood-vessels and lymphatics, and, in some parts, nerves and ganglia. There is also a considerable amount of fat, chiefly collected at the base of the heart, beneath the pericardium. Pericardium. - The heart is covered by a membranous sac called the pericardium (around the heart.) It consists of two parts: (1) an external fibrous portion, and (2) an internal, serous portion. Chap. IX] THE VASCULAR SYSTEM 149 (1) The external fibrous bag is composed of white fibrous tissue, and is shaped somewhat like an Indian's tepee. Above it covers the great blood- vessels for about an inch and a half (38 mm.) and blends with their sheaths. Below, it is firmly adhe- rent to the diaphragm. (2) The internal, or serous portion, of the per- icardium is a completely closed sac; it envelops the heart and lines the fibrous pericardium. The heart, however, is not within the cavity of the closed sac. (See diagram.) That portion of the serous pericar- dium which lines and is closely adherent to the heart is called the visceral portion (viscus organ): the remaining part of the serous pericardium, name- ly, that which lines the fibrous pericardium, is known as the parietal portion (paries, a wall). The cavity of the serous pericardium contains a small quantity of serous liquid. Its contiguous or opposed surfaces are lined by endothelium and are very smooth and polished. As the opposing sur- faces, owing to the constant contractions of the heart, are continually sliding one upon the other, they are admirably constructed to protect the heart from any loss of power by friction. Fig. 104. - Anterior View of Heart, Dis- sected, after Long Boiling, to show the Superficial Muscular Fibres. (Quain.) Fig. 105. - Diagram of Heart and Se- rous Pericardium. In A, heart and pericar- dium lying separately. In B, pericardium lying around heart. H, heart ; P, pericardium ; P.C. pericardial cavity ; P.P. parietal portion of pericardium ; V.P. visceral portion. 150 ANATOMY FOR NURSES [Chap. IX Endocardium. - The interior of the heart is lined by a delicate, smooth membrane, called the endocardium. This pavement' membrane (endothelium) lines all the cavities of the heart, and is continued into the blood-vessels, forming their innermost coat. The cavities of the heart. - The heart is divided from the base to the apex, by a fixed partition, into a right and left half, RIGHT PULMO - /INARY VEINS Left pulmonary veins Left auricular appendix Posterior coronary vessels Anterior coro- nary vessels Pert pointing to. aortic opening Anterior columna carnea cut in two and lifted up and back ^•External flap of mitral valve Cavity of left, ventricle Base of anterior' columna carnea Fig. 106. - Left Auricle and Ventricle, the Hind Wall of Each having been Removed. (Gerrish.) frequently called right and left heart. The two sides of the heart have no communication with each other after birth.1 The right always contains venous, and the left side arterial, blood. Each half is subdivided into two cavities, the upper, called auricle (atrium); the lower, ventricle (ventriculum). If we examine 1 Before birth they communicate by means of the foramen ovale. See page 193. Chap. IX] THE VASCULAR SYSTEM 151 these cavities, we notice that the muscular walls of the auricles are much thinner than those of the ventricles, and the wall of the left ventricle is thicker than that of the right. This difference in bulk is to be accounted for, as we shall see later on, by the greater amount of work the ventricles, as compared with the auri- cles, have to do. These cavities communicate with one another by means of constricted openings, the auriculo-ventricular ori- fices, which are strengthened by fibrous rings and protected and guarded by valves. The tricuspid valve. - The valve guarding the right auriculo- ventricular opening is composed of three irregular shaped flaps, or Fig. 107.-Cross-section through both Ventricles, showing the Shape of their Cavities and the Relative Thickness of their Walls. (Gerrish.) Fig. 108. - Valves of the Heart and Great Arteries, viewed from Above, the Auricles having been Removed. (Gerrish.) cusps, and is hence named tricuspid. The flaps are mainly formed of fibrous tissue covered by endocardium. At their bases they are continuous with one another, and form a ring-shaped membrane around the margin of the auricular opening: their pointed ends 152 ANATOMY FOR NURSES [Chap. IX are directed downwards, and are attached by cords, the chordae tendineae, to little muscular pillars, the papillary muscles,1 pro- vided in the interior of the ventricles for this purpose. The bicuspid valve.-The valve guarding the left auricular opening consists of only two flaps or cusps, and is named the bi- cuspid, or mitral valve. It is attached in the same manner as the tricuspid valve, which it closely resembles in structure, except that it is much stronger and thicker in all its parts. OPENING OF RIGHT CORONARY ARTERY SINUS OF . VALSALVA / I OPENING OF LEFT CORONARY ARTERY LEFT SEGMENT right: SEGMENT CORPUS? ARANTII POSTERIOR SEGMENT FIBROUS THICKEN- ING OF EDGE Fig. 109. -Aortic Valve. The artery has been cut open between the anterior and left posterior segments, and spread out. (Gerrish.) These valves oppose no obstacle to the passage of the blood from the auricles into the ventricles; but any flow forced back- wards gets behind the flaps of the valve (between the flap and the wall of the ventricle), and drives the flaps backwards and upwards, until, meeting at their edges, they unite and form a complete transverse partition between the ventricle and auricle. Being retained by the chordae tendinese, the expanded flaps of the valve resist any pressure of the blood which might otherwise force them back to open into the auricle; the papillary muscles, also, to which the chordae tendineae are attached, contract and shorten at the same time, and thus keep them taut. 1 Many large muscular prominences are observed in the ventricles; they are called " column® carneae" (fleshy columns). They are of three kinds:-• 1. Those attached at both ends and all of one side. 2. Those attached at both ends and nowhere else. 3. Those that have one extremity secured to the wall. These last are known as papillary muscles. Chap. IX] THE VASCULAR SYSTEM 153 Besides the openings between the auricles and ventricles, each ventricle has a large artery opening out of it. The pulmonary artery arises from the right ventricle. The aorta arises from the left ventricle. Semilunar valves. - The openings between the ventricles and arteries are each provided with a set of valves called the semilunar valves (aortic and pulmonary). These valves consist of three half-moon-shaped pockets, each pocket being attached by its convex border to the inside of the artery where it joins the ventricle, while its other border projects into the interior of the vessel. Small teat-like bodies, called the corpora Arantii, are attached to the centre of the free edge of each pocket. These bodies assist in the closure of these valves, which form a complete barrier to the passage of the blood from the arteries into the heart, but offer no resistance to the flow from the heart into the arteries. Each auricle has veins opening into it. The right auricle re- ceives blood from the superior vena cava, the inferior vena cava, and the coronary veins. The left auricle receives blood from the pulmonary veins. THE BEAT OF THE HEART So long as life lasts, the muscular tissue of the heart con- tracts and relaxes unceasingly with a short interval of rest. We may call the heart a muscular pump, the force of whose strokes is supplied by the contraction of muscular fibres, the strokes being repeated so many times a minute. It is con- structed and furnished with valves in such a way that, at each stroke, it drives a certain quantity of blood from the ventricles into the arteries, receiving, during the interval between that stroke and the next, the same quantity of blood from the veins. The contractions of the heart are rhythmical; that is to say, they occur in a certain order. First, there is a simultaneous con- traction of the walls of both auricles; immediately following this, a simultaneous contraction of both ventricles; then comes a pause, or period of rest, when the cycle is repeated. Systole. - The state of contraction is called the systole. Diastole. -The state of dilatation, or rest, is called the diastole. During the diastole, or period of rest, the blood is flowing into the auricles and beyond into the ventricles (the auriculo-ven- 154 ANATOMY FOR NURSES [Chap. IX tricular valves being open). Then the auricles and ventricles con- tract again in the same order as before, and their contractions are followed by the same pause as before. The rhythmical succession of the systole and diastole consti- tutes a cardiac cycle and occupies about 0.8 of a second. If the chest of an animal be opened and artificial respiration kept up, the heart may be watched beating, and a complete beat of the whole heart may be observed to take place as follows: - The great veins are seen, while full of blood, to contract in the neighbourhood of the heart, the wave of contraction running on towards the auricles, increasing in intensity as it goes. Arrived at the auricles, which are now full of blood, the wave of contrac- tion passes on to them, and they contract suddenly and quickly. During this contraction, the walls of the auricles press towards the auriculo-ventricular orifices, and the blood passes over the tricuspid and mitral valves into the ventricles, which have already been passively filled, and now become well distended by the extra supply from the auricles. The ventricles fill rapidly, and as soon as the auricular contraction is over, they in turn are seen to contract, their walls become very tense and hard; the tri- cuspid and mitral valves are closed by the blood getting behind the cusps, the apex is tilted upwards, and the heart twists some- what on its own axis. During the ventricular contraction the blood in the ventricles is, so to speak, cornered, and the only avenue of escape is through the semilunar valves into the arteries, which are seen to elongate and expand as the blood is pumped into them. The work of the auricles and ventricles is very unequal. All the auricles have to do is to pump the blood into the ventricles. The ventricles, on the contrary, have to pump the blood into tubes which are already full; and if there were no auriculo-ven- tricular valves, the blood would meet with less resistance in push- ing its way backward into the auricles than in pushing open the semilunar valves and forcing its way into the arteries. Hence the necessity, firstly, of the tricuspid and mitral valves, and secondly, of the superior thickness and strength of the walls of the ventricles, as compared with those of the auricles; and since the left side of the heart has a larger system of blood-vessels to supply, and more resistance to overcome than the right side, Chap. IX] THE VASCULAR SYSTEM 155 it follows that the left ventricle needs a thicker muscular wall than the right. The beat of the heart is caused by the rhythmical contractions of its muscular fibres. These contractions are automatic, and do not depend upon the central nervous system nor upon the blood in its chambers. That the contractions of the heart do not depend upon the nervous system is certain, for the heart will continue to beat for some time after its removal from the body. It probably depends upon a power inherent in the muscle tissue. The character of the beat, however, is governed and regulated by two sets of nerves. The first set come from the cerebro- spinal centre, and are supplied by the pneumogastric nerves. They are the inhibitory (check-rein) fibres, and slow the action of the heart. They weaken the systole and prolong the diastole. The other set come from the sympathetic nerves, and are accel- erating fibres, which increase not only the rapidity but the force of the beat. The diastole is shortened and the systole strength- ened. The sounds of the heart. - If the ear be applied over the heart, certain sounds are heard, which recur with great regularity. The first sound is a comparatively long, booming sound; the second, a short, sharp, sudden one. The sounds resemble the word lubb-dup. The first sound is caused by the contraction of the ventricles and the closure of the auriculo-ventricular valves. The second sound is caused by the closure of the semilunar valves. Heart murmurs. - These sounds in certain diseases of the heart become changed and obscure, and are replaced by various dis- tinctive and characteristic sounds called murmurs. ARTERIES These are hollow vessels that lead from the heart and are com- posed of three coats: - 1 A smooth endothelial lining. 2. A middle coat of fibrous elastic tissue with muscle fibres interlaced and circularly disposed around vessel. 3. An outer, dense, fibrous coat with fibres arranged longitudi- nally. The strength of an artery depends largely upon this coat; it is far less easily cut or torn than the other coats, and it serves 156 ANATOMY FOR NURSES [Chap. IX to resist undue expansion of the vessel. The arteries are also pro- tected by sheaths of connective tissue, which surround and blend with the outer coat. By virtue of their structure, the arteries are both contractile and elastic. The proportion of the muscular and elastic tissue differs in different arteries. The larger arteries are the more elastic and the smaller the more muscular. The elasticity and contractility of the arteries may be demonstrated by the following example: - If we tie a piece of a large artery at one end and inject fluid into the other end, the artery swells out to a very great extent, but will return at once to its former size when the fluid is let out. This great elasticity of the arteries adapts them for receiving the additional amount of blood thrown into them at each contrac- tion of the heart. Again, if we stimulate the muscular coat of any of the smaller arteries, the artery will shrink in size, the circularly disposed fibres contracting and narrowing the caliber of the vessel. This contractility is under the control of the nervous system, and as the organs of the body that are at rest do not require so much blood as those that are working actively, the nervous system, the master regu- lator of the body's work, is able to diminish or increase the supply of blood to the capillaries in different parts by acting upon this contractile muscular tissue in the arterial walls. The arteries do not collapse when empty, and when an artery is severed the orifice remains open. The muscular coat, however, contracts somewhat in the neighbourhood of the opening, and the elastic fibres cause the artery to retract a little within its sheath, so as to diminish its caliber and permit a blood-clot to plug the orifice.1 -OUTER COAT -ELASTIC LAYER )MIDDLE -CONTRACTILE LAYER $ COAT -INNER COAT Fig. 110. -Diagram of a Cross-section of an Artery, showing the Composition of its Tunics. (Gerrish.) 1 This property of the severed artery is an important factor in the arrest of hemorrhage. Chap. IX] THE VASCULAR SYSTEM 157 Vasa vasorum. - The walls of the arteries themselves are well supplied with blood-vessels. They are called vasa vasorum, or blood-vessels of the blood-vessels. Vasomotor. - They are also well supplied with nerves; such nerves are called vasomotor. As the arteries give off branches, they decrease in size until the smallest arteries are called arterioles, and at their distal ends the capillaries begin. Ihe walls of the capillaries are formed entirely of one layer of simple endothelium composed of flattened cells joined edge to edge by cement substance, and continuous with the layer which lines the arteries and veins. The capillaries communicate freely with one another and form interlacing networks of variable form and size in the different tissues. Their diameter is so small that often the blood-corpuscles must pass through them in single file, and in many parts they lie so closely together that a pin's point cannot be inserted between them. They are most abundant, and form the finest networks in those organs where the blood is needed for other purposes than local nutrition, such as, for example, for secretion or ab- sorption. In the glandular organs they supply the substances requisite for secretion; in the alimentary canal they take up some of the elements of digested food; in the lungs they ab- sorb oxygen and give up carbon dioxide; in the kidneys they dis- charge the waste products collected from other parts; all the time, everywhere through their walls, that interchange is going on which is essential to the renovation and life of the whole body. THE CAPILLARIES Fig. 111.-Fine Capil- laries from the Mesentery. (Collins.) THE VEINS The veins have three coats, and on the whole resemble the arteries in structure. They differ from them, however, in having 158 ANATOMY FOR NURSES [Chap. IX much thinner walls, and in their walls containing relatively much more white fibrous tissue and much less yellow elastic tissue. They are, therefore, not so elastic or contractile as the arteries, and their walls collapse when empty. Many of the veins, espe- cially those of the limbs, are provided with valves, which are me- chanical contrivances adapted to prevent the reflux of the blood. The valves are semilunar folds of the internal coat of the veins; the convex border is attached to the side of the vein, and the free edge points towards the heart. Should the blood on its onward course toward the heart be for any reason driven backwards, the refluent blood, getting be- hind the wall of the vein and the flaps of the valve, will press them inwards until their edges meet in the middle of the channel and close it up. The valves have usually two flaps, sometimes one, rarely three. The veins, like the arteries, are supplied with both blood-vessels and nerves; the supply, however, is far less abun- dant. It must be remembered that although the arteries, capillaries, and veins have each the distinctive structure above described, it is at the same time difficult to draw the line between the smaller artery and larger capillary and between the larger capillary and smallest vein. The veins on leaving the capillary networks only gradually assume their several coats, while the arteries dispense with their coats in the same imperceptible way as they approach the capillaries. Fig. 112. -A. part of a vein, laid open, with two pairs of valves ; B, longi- tudinal section of vein, showing valves closed. (Sharpey.) Chap. IX] THE VASCULAR SYSTEM 159 SUMMARY Smooth lining on inside -^Endocardium Muscle substance - Myocardium Involuntary. Striated. Composition Outside covering - Pericardium 1 11. Serous portion Visceral. Parietal. [2. Fibrous portion. Right auricle Receives blood. Thin walls. Right Heart Expels blood. Pulmonary artery. Thick walls. Divisions Right ventricle Left Heart Left auricle Receives blood. Thin walls. Left ventricle Expels blood. Aorta. Very thick walls. Superior vena cava - returns blood upper por- tion of body. Inferior vena cava - returns blood lower por- tion of body. Coronary veins - return blood from heart. Right Auricle Right Heart Tricuspid valve - composed of three cusps between right auricle and right ventricle. HEART 'Pulmonary artery - guarded by semilunar valves. Papillary muscles. ^Chordae tendineae. Right Ventricle 'Left Auricle । Two right pulmonary veins 1 Two left pulmonary veins Return blood from lungs. Bicuspid valve - Composed of two strong, thick cusps between left auricle and left ventricle. Left Heart 'Aorta - guarded by semilunar valves. Papillary muscles. Chordae tendinese. Left Ventricle Systole - State of contraction Diastole - State of dilatation or rest Cardiac cycle. Occupies 0.8 of a second. Heart-beat Regulated by Nerves Cerebro-spinal centre - Pneumogastric nerves, inhibitory fibres, slow the heart and weaken the systole. Sympathetic system - Accelerating fibres, increase rapidity and force of heart. Strengthen systole and shorten diastole. Heart Sounds 1st Lubb-caused by simultaneous contraction of both ventricles and closure of both auriculo-ventricular valves. 2d Dup- caused by closure of both semilunar valves. 160 ANATOMY FOR NURSES [Chap. IX Arteries ' Hollow tubes - carry blood from heart. Coats . . T. Endothelial lining. 2. Muscular and elastic tissue. 3. Fibrous tissue. Contractile and elastic. Capillaries . . . 'Tiny tubes - connect arteries and veins. One coat of simple endothelium. Communicate freely - form networks. 'Collapsible tubes - carry blood to heart. Three coats, same as arteries but thinner. Less elastic and contractile. Valves. 1-2-3 semilunar pockets. Veins Vasa vasorum - term applied to blood-vessels that are supplied to coats of other blood-vessels. Vasomotor - term applied to nerves supplied to blood-vessels. CHAPTER X THE VASCULAR SYSTEM CONTINUED: ARTERIAL DISTRIBU- TION AND VENOUS RETURN ARTERIAL DISTRIBUTION The arteries, which carry and regulate the supply of blood from the heart to the capillaries, are distributed throughout the body in a systematic manner, and before taking up the circulation, we must try to gain a general idea of this system of distribution, in TERMINAL. BRANCHES BICHOTOMOUS BRANCHING Fig. 113. - Diagram showing the Branchings, Anastomoses, and Confluence of Arteries. (Gerrish.) order that we may be able to locate the position of these important vessels. The arteries usually occupy protected situations, that they may be exposed as little as possible to accidental injury 161 162 ANATOMY FOR NURSES [Chap. X As they proceed in their course they divide into branches, the division taking place in different ways. (1) An artery may at once resolve itself into two branches of nearly equal size (dichotomous, or splitting in two). (2) It may give off several branches in succession and still maintain its character as a trunk. (3) It may give off one branch that divides into three equal branches. In this case the parent branch is called an axis. Example - coelic axis. An artery, after a branch has gone off from it, is smaller than before. A branch of an artery is less in diameter than the trunk from which it springs, but the collective capacity of all the branches into which an artery divides is greater than the parent vessel. Since the area of the. arterial system increases as its vessels divide, it is evident that the collective capacity of the smaller vessels and capillaries must be greater than the collective capacity of the trunks from which they arise. Or, in other words, the smallest arteries (arterioles) contain more blood than the aorta and pulmonary. As the same rule applies to the veins, it follows that the arterial and venous systems may be represented, as regards capacity, by two funnels whose apices are at the heart, and whose bases are united in the capillary system. The effect of this arrangement of the circulatory vessels is to make the blood flow more slowly as it passes through the. smaller and more widely distributed vessels, and to accelerate its speed in the larger and less numerous trunks. Anastomose, or inosculate.-The distal1 ends of arteries unite at frequent intervals, when they are said to anastomose, or inoscu- late. Such inosculations admit of free communication between the currents of the blood, tend to promote equality of distribution and of pressure, and to obviate the effects of local interruption. Plexus. - When a number of arteries form many inosculations within a limited area, it is described as a plexus or network. Arteries commonly pursue a tolerably straight course, but in some parts of the body they are tortuous. The facial artery, in its course over the face, and the arteries of the lips are extremely tortuous, so that they may accommodate themselves to the movements of the parts. The uterine arteries are also tortuous 1 Dista^means more remote from the trunk. Proximal, nearer the trunk. Chap. X] THE VASCULAR SYSTEM 163 to accommodate themselves to the increase in size of the uterus during pregnancy. - Temporal - External carotid ' Common carotid - Subclavian - Aorta ■ Axillary - Brachial - Radial -Ulnar - Palmar arch - Femoral -Popliteal -Anterior tibial - Posterior tibial -Dorsalis pedis Facial - Innominate - Heart - Aorta - Common iliac - External iliac* - Internal iliac - Fig. 114. - The Principal Arteries and Veins of the Body. (Morrow.) In describing the distribution of the arteries, we shall con- sider (1) the pulmonary artery, arising from the right ventricle of the heart, (2) the aorta, arising from the left ventricle of the heart. 164 ANATOMY FOR NURSES [Chap. X THE PULMONARY ARTERY The pulmonary artery conveys the dark blood from the right side of the heart to the lungs. The main trunk is a short, wide vessel (diameter 30 mm.) which arises from the right ventricle and runs for a distance of two inches (50 mm.) upward, back- ward, and to the left. Between the fifth and sixth thoracic vertebrae it divides into two branches, - the right and left pulmonary arteries, - which pass to the right and left lungs. (See Fig. 103.) THE AORTA The aorta is the main trunk of the arterial sys- tem. Springing from the left ventricle of the heart, it arches over the root of the left lung, de- scends along the verte- bral column, and after passing through the dia- phragm into the abdom- inal cavity, ends opposite the fourth lumbar verte- bra by dividing into the right and left, common iliac arteries. In this course the aorta forms a continuous single trunk, which gradually dimin- ishes in size from its commencement to its termination (from 28 to 17 mm.), and gives off larger or smaller branches at various points. It may be divided as follows: - (1) Ascending aorta.- The ascending aorta is the short part which is contained within the pericardium. Fig. 115. - Thoracic Aorta. (Gerrish.) Chap. X] THE VASCULAR SYSTEM 165 (2) Arch. - The arch is the part extending from the ascending aorta and forming a well-marked curve in front of the trachea, A lumbar vein' Fig. 116. - Abdominal Aorta. (Gerrish.) and around the root of the left lung to the border of the fourth thoracic vertebra. (3) Descending thoracic aorta. -The descending thoracic aorta 166 ANATOMY FOR NURSES [Chap. X is the comparatively straight part that extends from the lower border of the fourth thoracic vertebra on the left side to the opening in the diaphragm below the last thoracic vertebra. It has a length of from seven (175 mm.) to eight inches (200 mm.). (4) Abdominal aorta. - The abdominal aorta commences about the lower border of the last thoracic vertebra, and ter- minates below by dividing intp the two common iliac arteries. The bifurcation usually takes place about halfway down the body of the fourth lumbar vertebra, which corresponds to a spot on the front of the abdomen, slightly below and to the left of the umbilicus. Its length is about five inches (125 mm.). The ascending aorta. - The ascending aorta gives off two small branches, the right and left coronary arteries, which supply the substance of the heart with blood. (See Fig. 109.) Arch.- The arch gives off three branches: (1) innominate, (2) left common carotid, (3) left subclavian. Innominate. - The innominate (brachio-cephalic) artery arises from the right upper surface of the arch, ascends obliquely towards the right, until, arriving on a level with the upper margin of the clavicle, it divides into the right common carotid and right subclavian arteries. Its usual length is from one to two inches (25 to 50 mm.). Left common carotid. -The left common carotid arises from the middle of the upper surface of the arch of the aorta. Left subclavian. - The left subclavian arises from the left upper surface of the arch. The common carotid arteries.-As the left common carotid arises from the middle of the upper surface of the arch of the aorta, while the right common carotid arises at the division of the innominate, the left carotid is an inch or two longer than the right. They ascend obliquely on either side of the neck until, on a level with the upper border of the laryngeal prom- inence (Adam's apple) they divide into two great branches: (1) the external carotid, (2) the internal carotid (see Fig. 142). At the root of the neck the common carotids are separated from each other by only a narrow interval, corresponding with the width of the trachea; but as they ascend they are separated by a much larger interval, corresponding with the breadth of the larynx and pharynx. Chap. X] THE VASCULAR SYSTEM 167 The external carotid has eight branches, which are distributed to the throat, tongue, face, and walls of the cranium. The internal carotid is distributed to the brain and eye. It has many branches. The chief ones are the ophthalmic and cerebral. A remarkable anastomosis exists between the cerebral arteries at the base of the brain. The arteries are joined in such a manner as to form a complete circle, and this anastomosis is known as the "circle of Willis." It both equalizes the circulation of the blood in the brain and also provides, in case of destruction of one of the arteries, for the blood reaching the brain through the other vessels. The subclavian arteries. - The right subclavian arises at the Fig. 117. - Axillary and Subclavian Arteries. (Gerrish.) division of the innominate, and the left subclavian from the arch of the aorta. The subclavian arteries are the first portions of a long trunk which forms the main artery of the upper limb, and 168 ANATOMY FOR NURSES [Chap. X which is artificially divided for purposes of description into three parts; viz.: - 1. Subclavian, 2. Axillary, and 3. Brachial arter- ies. The subclavian artery passes a short way up the thorax into the neck, and then turns downwards to rest on the first rib. At the out- er border of the first rib it ceases to be called subclavian, and is contin- ued as the axillary. It gives off large branches to the back, chest, and neck. The axillary artery passes through the axilla, lying to the inner side of the shoulder joint and upper part of the arm. It gives off branches to chest, shoulder, and arm. The brachial artery (continuation of the axillary) extends from the axillary space to just below the bend of the elbow, where it divides into the ulnar and radial arteries. It may be readily located, lying in the depression along the inner bor- der of the biceps muscle. Pressure made at this point on the artery, from before backwards against the humerus, will control the blood sup- ply to the arm. The ulnar, the larger of the two vessels into which the brachial di- vides, extends along the side of the forearm into the palm of the hand, where it terminates in the superficial palmar arch. The radial artery appears, by its direction, to be a continuation of the brachial, although it does not equal the ulnar in size. It extends along the front of the forearm as far as the lower end of the radius, below which it turns around the outer border of Brachial artery Fig. 118. - Deep Anterior View of the Arteries of the Arm, Forearm, and Hand. Chap. X] THE VASCULAR SYSTEM 169 the wrist, descends between the bones of the thumb and fore- finger, and passes forward into the palm of the hand. It ter- minates in the deep palmar arch. The superficial and deep palmar arches supply the hand with blood. Thoracic aorta.-The branches derived from it are numerous but small. The principal ones are: - 1. Intercostals (22), one to each intercostal space on each side. / 2. Pericardial to the pericardium. 3. Bronchial to the lung tissues. 4. (Esophageal to the oesophagus. 5. Mediastinal to the lymph nodes and tissues between the lungs. Abdominal aorta. - It gives off numerous branches, which may be divided into two sets: - 1. Visceral, or those which supply the viscera. 2. Parietal, or those which are distributed to the walls of the abdomen. The visceral group consists of (1) the cceliac axis, (2) the superior mesenteric, (3) the inferior mesenteric, (4) the renal, (5) the adrenal, and (6) the spermatic (male) or ovarian (female). The parietal group consists of (1) the phrenic, (2) the lumbar, and (3) the middle sacral. Visceral group: - The cceliac artery, or axis, is a short, wide vessel, usually not more than half an inch (12.5 mm.) in length, which arises from the front of the aorta, close to and below the opening in the diaphragm. It divides into three branches; viz. the gastric, which supplies the stomach; the hepatic, which supplies the liver; and the splenic, which supplies the spleen, and in part the stomach and pancreas. The superior mesenteric artery arises from the fore part of the aorta, a little below the cceliac axis. It supplies the whole of the small intestine beyond the first portion (the duodenum) close to the stomach, and half of the large intestine. The inferior mesenteric artery arises from the front of the aorta, about an inch and a half (38 mm.) above its bifurcation, and supplies the lower half of the large intestine. Continued under the name of the superior hemorrhoidal artery, it also supplies the rectum. 170 ANATOMY FOR, NURSES [Chap. X The renal arteries are of large size, in proportion to the bulk of the organs (kidneys) which they supply. They arise from the sides of the aorta, about half an inch (12.5 mm.) below the superior mesenteric artery, that of the right side being generally a little lower down than that of the left. Each is directed out- Fig. 119.- Superior Mesenteric Artery. (Gerrish.) wards, so as to form nearly a right angle with the aorta. Before reaching the kidney, each artery divides into four or five branches. The adrenal arteries are of small size. They arise from the side of the aorta, a little above the superior mesenteric. They supply the adrenal or supra-renal bodies. (See page 215, Chapter XII.) Chap. X] THE VASCULAR SYSTEM 171 The spermatic arteries in the male arise close together from the front of the aorta, a little below the renal arteries. They are distributed to the testes. The ovarian arteries in the female arise from the same portion | INFERIOR MESENTERIC MIDDLE^ HEMORRHOIDAL' INFERIOR HEMORRHOIDAL Fig. 120. - Inferior Mesenteric Artery. (Gerrish.) of the aorta as the spermatic arteries in the male. They supply the ovaries, and, joined to the uterine artery, - a branch of the internal iliac, - also assist in supplying the uterus. Dur- ing pregnancy the ovarian arteries become considerably enlarged. Parietal group: - The phrenic arteries arise from the aorta above the coeliac axis and are distributed to the diaphragm. 172 ANATOMY FOR NURSES [Chap. X The lumbar arteries arise from the aorta, and the various branches, dorsal, spinal, and abdominal, supply the muscles and walls of the respective regions that their names suggest. SUPERFICIAL EPIGASTRIC SUPERFICIAL EXTERNAL PUDIC ANTERIOR CRURAL- NERVE EXTERNAL _ CIRCUMFLEX ^•DEEP EXTERNAL PUD,C SUPERIOR EXTERNAL-A I ARTICULAR \ Wj -ANASTOMOTICA MAGNA -INFERIOR INTERNAL ARTICULAR INFERIOR EXTERNAL- ARTICULAR Fig. 121. - Femoral Artery. (Gerrish.) The middle sacral artery arises from the lower end of the ab- dominal aorta and passes down to the sacrum and coccyx. Chap. X] THE VASCULAR SYSTEM 173 Common iliac. - The com- mon iliac arteries, commencing at the bifurcation of the aorta, pass downwards and outwards about two inches (50 mm.), and then each divides into the inter- nal (or hypogastric) and exter- nal iliac arteries. The internal iliac artery (or hypogastric) supplies branches to the walls and viscera of the pelvis. The external iliac artery forms a large, continuous trunk, which extends downwards in the lower limb to just below the knee; it is named in successive parts of its course external iliac, femoral, and popliteal. The external iliac is placed within the abdomen, and ex- tends from the bifurcation of the common iliac to the lower border of the inguinal ligament, where it enters the thigh and is named femoral. The femoral artery lies in the upper three-fourths of the thigh, its limits being marked above by the inguinal ligament, and below by the opening in the great adductor muscle, after passing through which the ar- tery receives the name of pop- liteal. In the first part of its course the artery lies along the middle of the depression on the inner aspect of the thigh, known as Scarpa's triangle. In ANTERIOR TIBIAL ANTERIOR PERONEAL Fig. 122. - Arteries in the Dorsai Part of the Leg. (Geirish.) 174 ANATOMY FOR NURSES [Chap. X this situation the beating of the artery may be felt, and the circulation through the vessel may be most easily controlled by pressure. The popliteal artery, continuous with the femoral, is placed at the back of the knee; just below the knee- joint it divides into the posterior tibial and anterior tibial arteries. The posterior tibial artery lies along the back of the leg, and extends from the bifurcation of the popliteal to the an- kle, where it di- vides into the internal and external plantar arteries. The peroneal artery is a large branch given off by the pos- terior tibial just about an inch (25 mm.) below the bifurcation of the popliteal. The anterior tibial artery, the smaller of the two divisions of the popliteal trunk, extends along the front of the leg to the . bend of the ankle, whence it is prolonged into the foot under the name of the dorsal artery. This unites with the external and internal plantar arter- ies to form the plantar arch which supplies blood to the foot.1 ANTERIOR TIBIAL RECURRENT-/ ANTERIOR TIBIAL' NERVE ANTERIOR PERONEAL EXTERNAL MALLEOLAR' -INTERNAL MALLEOLAR DORSALIS . PEDIS Fig. 123.-Anterior Tibial Artery. (Gerrish.) 1 Drawing the outline of the aorta with its branches as an arterial tree will greatly aid the student in mastering the arterial distribution. Chap. X] THE VASCULAR SYSTEM 175 Fig. 124. Arteries of the Dorsum of the Foot. Of the dorsal interosseous only the second is labelled. (Gerrish.) 176 ANATOMY FOR NURSES [Chap. X VENOUS RETURN The arteries begin as large trunks, which gradually become smaller and smaller until they end in the small capillary tubes, while the veins begin as small branches which at first are scarcely distinguishable from the capillaries. These small branches, re- ceiving the blood from the capillaries throughout the body, unite and reunite until they form two sets of veins - a subcutane- ous and a deep-set. Entrance of •vena azygos .Branch of pul- monary artery Fig. 125. - Pulmonary Veins, seen in a Dorsal View of the Heart and Lungs. The left lung is pulled to the left, and the right lung has been partly cut away to show the ramifications of the air-tubes and blood-vessels. (Gerrish.) Subcutaneous - are found immediately beneath the skin. Deep-set - accompany the arteries and are usually called by the same names. These two sets of veins have very frequent communications with each other, and the anastomoses of veins are always more numerous than those of arteries. Chap. X] THE VASCULAR SYSTEM 177 Venee comites - where two deep-set veins accompany an artery, they are so called. All the veins of the body are naturally divided into two groups: (1) pulmonary and (2) systemic. THE PULMONARY VEINS The pulmonary veins are four short trunks which convey the scarlet blood from the lungs to the left side of the heart, and which are found - two on each side - in the root of the corre- sponding lung. The pulmonary veins have no valves. THE SYSTEMIC VEINS The systemic veins are naturally divided into two groups: - 1. Those from which the blood is carried to the heart by the superior vena cava, viz. the veins of the head, neck, upper ex- tremities, and the walls of the thorax. Coronary veins. - In this group we may include the veins of the heart, which, however, pass directly into the right auricle without entering the superior vena cava. 2. Those from which the blood is carried to the heart by the inferior vena cava, viz. the veins of the lower limbs, the lower part of the trunk, and the abdominal viscera. 1. The blood returning from the head and neck flows on each side into two principal veins, the external and internal jugular. The external jugular commences near the angle of the jaw by the union of two smaller veins, and descends almost vertically in the neck to its termination in the subclavian vein. The internal jugular, receiving the blood from the cranial cav- ity, descends the neck close to the outer side of the internal and common carotid arteries. It unites at a right angle with the subclavian to form the innominate (brachio-cephalic) vein.1 The subclavian veins. - The blood from the upper limbs is returned by a superficial and deep set of veins. The superficial are much larger than the deep, and take a greater share in re- 1 Note on Venous Circulation of the Skull. - The blood from the skull is returned from the smaller veins to the internal jugular veins by channels which are not strictly veins, but sinuses. These sinuses are spaces left between the layers of the dura mater, and are lined by a continuation of the lining membrane of the veins. 178 ANATOMY FOR NURSES [Chap. X turning the blood, especially from the distal portion of the limb. The deep veins accompany the arteries, and are called by the same names. From the hand and wrist the blood flows into the ulnar and radial veins. They unite to form the brachial, then they in turn form the axillary and it becomes the subclavian. Both sets are provided with valves, and the superficial as well as the deep terminate in the subclavian vein. ANTERIOR. JUGULAR ~ I INTERNAL MAMMARY Fig. 126. -Veins of the Neck and Upper Part of Thorax. Front View. (Gerrish.) The innominate veins. - The innominate (brachio-cephalic) veins, commencing on each side by the union of the subclavian and internal jugular, behind the inner end of the clavicle, trans- mit the blood returning from the head and neck, the upper Chap. X] THE VASCULAR SYSTEM 179 limbs, and a part of the thoracic wall; they end below by unit- ing to form the superior vena cava. Both innominate veins are joined by many side tributaries: they also receive, at the Fig. 127.---Superficial Veins of the Front of the Leg and Foot. (Ger- rish.) Fig. 128. - Superficial Veins of the Front of the Right Thigh. (Gerrish.) 180 ANATOMY FOR NURSES [Chap. X junction of the subclavian and internal jugular, the lymph; on the left side from the thoracic duct, and on the right from the right lymphatic duct. THE SUPERIOR VENA CAVA The superior, or descending vena cava, is formed by the union of the right and left innominate veins. It is about three inches (75 mm.) long, and opens into the right auricle, opposite the third rib. 2. The blood from the lower limbs is also returned by a superficial and deep set of veins. They are more abundantly sup- plied with valves than the veins of the upper limbs. The internal, or long saphe- nous, and the external, or short saphenous, are the two largest superficial veins. The internal saphenous extends from the ankle to within an inch and a half (38 mm.) of the inguinal ligament. It lies along the inner side of the leg and thigh and terminates in the femoral vein. The external saphenous arises from the sole of the foot, and, passing up the back of the leg, ends in the deep popliteal. The deep veins accompany the arteries, and as in the upper limbs are called by the same names. The veins from the foot empty into anterior tibial and posterior tibial veins. They unite to form the pop- liteal, which is continued as the femoral and becomes the external iliac. The external iliacs receive the blood from the deep and superficial veins of the lower limbs. The internal iliacs receive the blood from the pelvis, and unite with the external iliacs to form the common iliacs. The common iliacs.-The common iliacs extend from the Fig. 129. - Super- ficial Veins of the Dorsum of the Leg. (Gerrish.) Chap. X] THE VASCULAR SYSTEM 181 base of the sacrum to the fourth lumbar vertebra, and then the two common iliacs unite to form the inferior vena cava. Fig. 130. - Portal System of Veins. The liver is turned upward and back- ward, and the transverse colon and most of the small intestines are removed. (Gerrish.) 182 ANATOMY FOR NURSES [Chap. X THE INFERIOR VENA CAVA The inferior, or ascending vena cava, returns the blood from the lower limbs, pelvis, and abdomen. It begins at the junction of the two common iliacs, and thence ascends UPPER END OF THORACIC DUCT along the right side of the aorta, perforates the diaphragm, and terminates by entering the right auricle of the heart. The inferior vena cava receives many tributaries, the chief of which are the lumbar, ovarian, renal, and hepatic veins. Fig. 131. - Azygos and Intercostal Veins. (Gerrish.) Chap. X] THE VASCULAR SYSTEM 183 The portal circulation. - The veins, which bring back the blood from the stomach, intestines, spleen, and pancreas, do not take it directly to the inferior vena cava. They first join to form a large trunk, - the portal vein, - and carry this blood to the liver. When the portal vein enters the liver, it breaks up into capillaries, which, after branching throughout the liver substance, unite to form the hepatic veins; by them the blood is conveyed into the inferior vena cava. This constitutes what is called the portal circulation, and is the only example in the body of a vein breaking up into capillaries. Supplementary channel. - The blood from the spine, walls of thorax, and abdomen is chiefly returned by the right and left azygos veins, which are longitudinal vessels, resting against the thoracic portion of the spinal column. They communicate below with the inferior vena cava, and terminate above in the superior vena cava: they thus form a supplementary channel by which blood can be conveyed from the lower part of the body to the heart in case of obstruction in the inferior vena cava. 184 ANATOMY FOR NURSES [Chap. X SUMMARY PLAN OF ARTERIAL DISTRIBUTION Begin as large trunks, grow smaller. Usually deep-seated for protection. Anastomose or inosculate. Usually straight (facial and uterine are tortuous). Arteries Main Arteries Pulmonary. Aorta. Pulmonary Arteries Right pulmonary artery - right lung. Left pulmonary artery - left lung. Ascending Aorta R. and L. coronary - supply the heart. fInt. carotid - brain and eye. Ext. carotid-throat, tongue,; [ face, walls of cranium. Innominate R. c. carotid I. Arch of Aorta R. subclavian, - axillary - brachial | Ulnar • Superficial palmar' arch. Radial {Deep palmar arch. L. c. carotid -same branches as R. c. carotid. L. subclavian - same branches as R. subclavian. II. Thoracic Aorta 7 to 8 in. Intercostal- to the intercostal spaces. Pericardial - to the pericardium. Bronchial - to the lung tissue. (Esophageal - to the oesophagus. Mediastinal - to the lymph nodes and tissues between lungs. AORTA Diaphragm muscle is dividing line between thoracic and abdominal aorta. [ Gastric - stomach. Hepatic - liver. Splenic - spleen. Coeliac axis Sup. mesenteric Small intestine except duo denum. Half of large intestine. III. Abdominal Aorta 5 in. Visceral Group Inf. mesenteric Lower half of large intes- tine and rectum. Renal - kidneys. Adrenal - adrenal bodies. Spermatic - testes. Ovarian - ovaries and uterus. " Phrenic - diaphragm. Lumbar - dorsal, spinal, and abdominal walls. L Middle sacral- sacrum and coccyx. Parietal Group Chap. X] THE VASCULAR SYSTEM 185 "Internal iliac - walls and viscera of pelvis. Common Iliac Arteries 2 in. External iliac - femoral - popliteal Posterior tibial Ext. plantar Int. plantar Plantar arch. Anterior tibial Peroneal. Dorsal. 'Begin small, grow larger. Both deep-seated and subcutaneous. Frequent anastomosis. Vense comites " - attendant veins. PLAN OF VENOUS RETURN Veins . . . . Veins . . . . Pulmonary Two from each lung. Systemic Sup. vena cava Inf. vena cava ■ and all their tributaries. The veins from the lungs unite to form 2 R. pulmonary veins 2 L. pulmonary veins I Carry blood from lungs to left [ auricle. The veins from the head, face, and neck unite to form External jugular veins - terminate in subclavian. Internal jugular veins - unite with subclavian. The deep-seated and superficial veins from the upper limbs unite to form R. subclavian > and L. subclavian Unite w'ith int. jugular on each side to form innominate. Right and left in- nominate Unite to form superior vena cava. The deep-seated and superficial veins from the lower limbs unite to form External iliacs Unite to form common iliacs. The veins from pelvis unite to form Internal iliacs Right and left common iliacs Unite to form inferior vena cava. Supplementary Channel The right and left azygos veins connect with sup. vena cava above and inf. vena cava below. PORTAL CIRCULATION Intestines Stomach Spleen Pancreas _ Veins from . Unite to form portal vein. Carries blood to liver - breaks up into capillaries, then unites to form hepatic veins. Portal Vein . Hepatic Veins - Empty into inferior vena cava. CHAPTER XI THE VASCULAR SYSTEM CONTINUED: THE GENERAL CIRCULA- TION; THE PULSE AND ARTERIAL TENSION; VARIATIONS IN THE CAPILLARY CIRCULATION; FCETAL CIRCULATION THE GENERAL CIRCULATION OF THE BLOOD To trace the general circulation, we will begin with the venous blood, which is returned to the right auricle by the superior and inferior venae cavae. It enters and fills the right auricle, and beyond into the right ventricle, then the auricle contracts and forces the blood over the open tricuspid valve into the ventricle which has already been passively filled, and now becomes well distended by the extra supply of blood. Almost instantly the ventricle contracts, the blood gets behind the cusps of the tri- cuspid valve and closes them, and thus is forced over the open semilunar valves into the pulmonary artery. The pulmonary artery carries the blood to the lungs, where it receives a fresh supply of oxygen and gives up the carbon dioxide with which it has become loaded during its circulation through the body. After completing the circuit of the lungs, it is returned by the pulmonary veins to the left auricle and into the left ventricle. The left auricle now contracts and forces the blood over the open bicuspid valve into the left ventricle, just as described for the right side of the heart. Upon contraction of the left ventri- cle the bicuspid valve is closed (in the same way as the tricuspid), the blood is forced over the open semilunar valve into the aorta to be carried through the body. The semilunar valves are closed by the excessive pressure within the pulmonary artery and aorta as soon as the relaxation of the ventricles occurs. From the aorta and its branches the blood travels in the capillaries to every part of the body. The capillaries unite to form veins, and finally the blood is returned by means of the venae cavae to the 186 Chap. XI] THE VASCULAR SYSTEM 187 right auricle, which brings it back to where we started from. It is estimated that it takes a drop of blood about twenty-two seconds to make this circuit. Pulmonary circulation. - The lesser circulation from the right ventricle to the left auricle is called the pulmonary circulation. The purpose of the pulmonary circula- tion is to obtain oxygen and get rid of carbon dioxide, which is a waste product. Systemic circulation. - The more extensive circulation from the left ventricle to all parts of the body (by means of the aorta and its branches), and the return to the right auricle (by means of the venae cavae), is known as the systemic circulation. The purpose of the systemic circu- lation is to carry oxygen and nutri- tive substances to all parts of the body and gather up waste products. This double circulation, pulmo- nary and systemic, is constantly and simultaneously going on, as at each beat of the heart the contrac- tion of both ventricles drives a certain quantity of blood, probably amounting to six ounces, with great force into both the aorta and pul- monary artery. The heart is a wonderfully busy organ that pumps away at the rate of about seventy-two strokes to a minute all the days of one's life. At each contraction the ventricles pump about six ounces of blood, and in a day this is equivalent to moving about twenty tons. The only rest the heart has is dur- Fig. 132. - Diagram of the Circulation: 1, heart; 2, lungs; 3, head and upper extremities; 4, spleen; 5, intestine; 6, kidney; 7, lower extremities; 8, liver. (Collins.) 188 ANATOMY FOR NURSES [Chap. XI ing the diastole, or dilatation, a period of about 0.4 of a second between each beat. Factors governing circulation. - The perfect circulation of the blood is dependent upon certain factors, the chief of which are: (1) the character of the heart-beat; (2) the contraction and relaxation of the minute arteries; (3) the elasticity and extensibility of the arterial walls; (4) the perfect adjustment of the valves. (1) The character of the heart-beat is mainly determined by the condition of its muscular substance, and any interference with the nutrition of the heart leading to degeneration of its muscular walls very seriously affects the heart's action. (2) The contraction and relaxation of the smaller arteries is under the influence of the nervous system. The muscular tissue found in the walls of these vessels is supplied with non- medullated nerve-fibres. Stimulation of one set of these fibres (vaso-constrictor) causes contraction of the muscle-fibres and constriction of the arteries; stimulation of a second set (vaso- dilator) causes a relaxation of the muscle-fibres, and dilatation of the arteries. The widening and narrowing of these arteries not only affects the local circulation in different parts of the body, but the amount of resistance they oppose to the arterial impulse also influences in some degree the character of the heart-beat. The term "tone of the arteries" is used to express the normal degree of contracture of the arterial walls. (3) The elasticity and extensibility of the arteries change with the age of the individual. As we grow older the arterial walls grow stiffer and more rigid, and become less well adapted for the unceasing work they are called upon to perform. (4) The valves also show signs of age as years advance, and even if not injured by disease, do not adjust themselves so per- fectly as in early life. Still, the heart has a marvellous facility for adjusting itself to changed conditions, and the circulation of the blood may go on for years with the integrity of the vascular mechanism greatly impaired. Some features of arterial circulation. - The flow of blood into the arteries is most distinctly remittent; sudden, rapid dis- charges alternating with relatively long intervals during which Chap. XI] THE VASCULAR SYSTEM 189 the arteries receive no blood from the heart. Every time the heart beats just as much blood flows from the veins into the right auricle as escapes from the left ventricle into the aorta, but this inflow is much slower and takes a longer time than the discharge from the ventricles. THE PULSE When the finger is placed on an artery, a sense of resistance is felt, and this resistance seems to be increased at intervals, corresponding to the heart-beat, the wall of the artery at each heart-heat being felt to rise up or expand under the finger. This alternate contraction and expansion of the artery consti- tutes the pulse; and in certain arteries which lie near the sur- face this pulse may be seen with the eye. When the finger is placed on a vein, very little resistance is felt; and, under ordi- nary circumstances, no pulse can be perceived by the touch or by the eye. As each expansion of an artery is produced by a contraction of the heart, the pulse, as felt in any superficial artery, is a con- venient guide for ascertaining the character of the heart's action.1 The radial artery at the wrist, owing to its accessible situation, is usually employed for this purpose. Any variation in the frequency, force, or regularity of the heart's action is indicated by a corresponding modification of the pulse at the wrist. The average frequency of the pulse in man is seventy-two beats per minute. This rate may be increased after eating or by muscular action. Even the variation of the muscular effort entailed between the standing, sitting, and recumbent positions will make a difference in the frequency of the pulse of from eight to ten beats per minute. Mental excitement may also produce a temporary acceleration, varying in degree with the peculiarities of the individual. Age has a marked influence. At birth the pulse rate is about 130 per minute; at three years, 100; in adult life, 72; in old age, 65. It is somewhat more rapid in women than in men and is lowered during sleep. Idiosyncrasies are frequently met with.. A person in perfect health may have a 1 The nurse should practise " taking the pulse" in the following arteries: - carotid facial temporal brachial radial femoral dorsalis pedis. 190 ANATOMY FOR NURSES [Chap. XI much higher or a much lower rate than 72. The relative fre- quency of the pulse and respirations is about three or four heart- beats to one respiration. As a rule, the rapidity of the heart's action is in inverse ratio to its force. An infrequent pulse, within physiological limits, is usually a strong one, and a frequent pulse comparatively feeble. The same is true in disturbance of the heart's action in disease, the pulse in fever or debilitating affections becoming weaker as it grows more rapid. Arterial tension. - When an artery is severed, the flow of blood from the proximal end (that on the heart side) comes in jets corresponding to the heart-beats, provided the artery be near the heart. The larger the artery, and the nearer to the heart, the greater the force with which the blood issues, and the more marked the intermittence of the flow. If the vessel severed be small and remote from the heart, the jet is constant. When a corresponding vein is severed, the flow of blood, which is chiefly from the distal end (that away from the heart), is not intermittent, but continuous; the blood comes out with com- paratively little force, and "wells up" rather than "spurts out." The continuous, uninterrupted flow of blood in the veins is caused by the elasticity of the arterial walls. On account of the small size of the capillaries and small arteries, the blood meets with a great deal of resistance in passing through them; and in consequence the blood cannot get through the capillaries into the veins as rapidly as it is thrown into the arteries by the heart. The whole arterial system, therefore, becomes over-dis- tended with blood, and the greater the resistance, the greater the pressure on, and distension of, the arterial walls. The fol- lowing illustration will explain how the elasticity of the arteries enables them to deliver the blood in a steady flow to the veins through the capillaries. If a Davidson syringe be fastened to one end of a long piece of elastic tubing, and water be pumped through the tubing, it will flow from the far end in jerks. But if we diminish the caliber of the orifice in the end of the tubing, or offer in any way resistance to the outflow of the water, the tubing will distend, its elasticity be brought into play, and the water flow from the Chap. XI] THE VASCULAR SYSTEM 191 encl not in jerks, but in a stream, which is more and more com- pletely continuous the longer and more elastic the tubing. Substitute for the syringe the heart, for the diminished outlet the small arteries, for the tubing the whole arterial system, and we have exactly the same result in the living body. Through the action of the elastic arterial walls the separate jets from the heart are blended into one continuous stream. The whole force of each contraction of the heart is not at once spent in driving a certain quantity of blood onwards; a part only is thus spent; the rest goes to distend the elastic arteries. But during the interval between that beat and the next, the distended arter- ies are narrowing again, by virtue of their elasticity, and so are pressing the blood on in a steady stream into the capillaries with as much force as they were themselves subjected to when dis- tended by the contraction of the heart. The degree of tension to which the arterial walls are subjected depends upon the force of the heart-beat, and upon the resist- ance offered by the smaller arteries, the normal general blood pressure being mainly regulated by the "tone" of the minute arteries. Variations in the capillary circulation. - Most of the changes in the capillary circulation are likewise dependent upon the condition of the smaller arteries. When under certain nervous influences the arterioles contract, the blood supply to the capil- laries is greatly lessened; when, on the other hand, they dilate, the blood supply is greatly increased. The phenomena pro- duced by these local variations in the blood supply of certain parts are very familiar to us; the redness of skin produced by an irritating application, the blushing or paling of the face from mental emotion, the increased flow of blood to the mucous membranes during digestion, being all instances of this kind. The diameter of the capillaries themselves also exerts an influence upon the capillary circulation. If some transparent tissue, preferably the web of a frog's foot, be watched under the microscope, it will be observed that in the small capillaries the corpuscles are pressed through the channel in single file, each corpuscle as it passes occupying the whole bore of the capillary. In the larger capillaries and smaller arteries and veins the red corpuscles run in the middle of the channel, forming a coloured 192 ANATOMY FOR NURSES [Chap. XI core, between which and the sides of the vessels is a colourless layer containing no red corpuscles, or only a few, and called the "peripheral zone." In the peripheral zone are frequently seen white corpuscles, sometimes clinging to the walls of the vessel, sometimes rolling slowly along, and in general moving irregularly, stopping awhile, and then suddenly moving on again. Abnormal variations.-These are the phenomena of the normal circulation, but a different state of things sets in when the con- dition of the blood-vessels is altered in inflammation.1 If an irritant, such as a drop of chloroform, be applied to the portion of transparent tissue under observation, the following changes may be seen to occur: the arteries dilate, the blood flows in greater quantity and with more rapidity, the capillaries become filled with corpuscles, and the veins appear enlarged and full. This condition of distension may pass away, and the blood- vessels return to their normal state, the effect of the irritant having merely produced a temporary redness. The irritant, however, usually produces a more decided change. The white corpuscles begin to gather in the peripheral zones, and this takes place though the vessels still remain dilated and the stream of blood still continues rapid, though not so rapid as at first. Each white corpuscle exhibits a tendency to stick to the sides of the vessels, and, driven away from the arteries by the stronger arterial current, becomes lodged in the veins. Since white corpuscles are continually arriving on the scene, the inner surface of the veins and capillaries soon become lined with a layer of these cells. Now, though the vessels still remain dilated, the stream of blood begins to slacken, and the white corpuscles lying in contact with the walls of the vessels are seen to thrust themselves through the distended walls into the lymph spaces outside. This migration of the white cells is accomplished by means of their amoeboid movements. They thrust elongated processes through the walls, and then, as these processes increase in size, the body of the cell passes through into the enlarged process beyond, the perforation appearing to take place in the cement substance between the pavement epithelial cells form- 1 The following account of the changes occurring in inflammation does not strictly belong to a text-book on physiology, but I have ventured to in- troduce it, as especially interesting to nurses, out of "Foster's Physiology." Chap. XI] THE VASCULAR SYSTEM 193 ing the walls of the vessels. Through this migration, the lymph spaces around the vessels in the inflamed area become crowded with white corpuscles. At the same time the lymph not only increases in amount, but changes somewhat in its chemical characters; it becomes more distinctly and readily coagulable, and is sometimes spoken of as "exudation fluid." This change of the lymph with the increased quantity, together with the dilated, crowded condition of the blood-vessels, gives rise to the swelling which is one of the features of inflammation. If the inflammation now passes away, the white corpuscles cease to emigrate, cease to stick so steadily to the sides of the vessels, the stream of blood quickens again, the vessels regain their ordinary caliber, and a normal circulation is reestablished. But this inflammatory condition, instead of passing off, may go on to a further stage; and, if this is the case, more and more white corpuscles, arrested in their passage, crowd and block the channels, so that, though the vessels remain dilated, the stream becomes slower and slower, until at last it stops altogether, and stagnation or "stasis" sets in. The red corpuscles, in this condition of things, are driven in among the white corpuscles, the vessels are filled and distended with a mingled mass of red and white corpuscles, and it may now be observed that the red corpuscles also begin to find their way through the distended and altered walls of the capillaries into the lymph spaces outside. This is called the diapedesis of the red corpuscles. This stagna- tion stage of inflammation may be the beginning of further mis- chief and of death to the inflamed tissue, but it too may, like the earlier stages, pass away. FCETAL CIRCULATION Certain structures are necessary to the performance of foetal circulation but are of no use after birth. They are as follows: - (1) Foramen ovale.--An opening between the two auricles. It furnishes direct communication between them. (2) Ductus arteriosus. - A blood-vessel connecting the aorta and pulmonary artery. (3) Ductus venosus.- A blood-vessel connecting the umbili- cal vein and the inferior vena cava. 194 ANATOMY FOR NURSES [Chap. XI arterial blood Fig. 133. - Diagram of Circulation before Birth. Foetal type. (Cooke.) VENOUS, BLOOD (4) The placenta and umbilical cord. - By means of the pla- centa the child is nourished and obtains oxygen. The cord is made up of two arteries and one large vein protected by " Wharton's Chap. XI] THE VASCULAR SYSTEM 195 jelly." The vein carries the oxygenated blood from the placenta to the foetus. The arteries carry the impure blood from the foetus to the placenta. After birth these structures are of no further use. It is important that the "foramen ovale" should close as soon as the child breathes, else if the arte- rial and venous blood continue to mix a "blue baby" will be seen. Course of the blood. -■ The oxygenated blood for the nutrition of the foetus is carried from the placenta along the umbilical cord by the umbilical vein. Entering the foetus the blood is conveyed into the inferior vena cava partly through the liver but chiefly through the "ductus venosus" which connects these two vessels. From the inferior vena cava it enters the right auricle, passes through the foramen ovale into the left auricle, thence into left ventricle, and out through the aorta, which dis- tributes it principally to the upper extremities. The blood from the head and upper extremities returns by the superior vena cava to the right auricle, then passes into the right ventricle, and out through the pulmonary artery to the lungs. As the lungs in the foetus are solid, they require very little blood (only for nutrition), and the greater part of the blood passes through the ductus arteriosus into the descending aorta, where, mixing with the blood delivered to the aorta by the left ventricle, it descends to supply the lower extremities of the foetus. The chief portion of this blood is carried back to the placenta by the two umbilical arteries, but a small amount passes back into the ascending vena cava and mixes with the blood from the placenta. From this description of the foetal circulation, it will be seen: - 1. That the placenta serves the double purpose of a respiratory and nutritive organ, receiving the venous blood from the foetus, and returning it again charged with oxygen and additional nutritive material. 2. That the liver receives pure blood directly from the placenta; hence the large size of this organ at birth. 3. That the blood from the placenta passes almost directly into the arch of the aorta, and is distributed by its branches to the head and upper extremities; hence the large size and perfect development of these parts at birth. 196 ANATOMY FOR NURSES [Chap. XI 4. That the blood in the descending aorta is chiefly derived from that which has already circulated in the upper extremities, and, mixed with only a small quantity from the left ventricle, is distributed to the lower extremities; hence the small size and imperfect development of these parts at birth. Development of blood-vessels and corpuscles. - The blood-vessels and red corpuscles are formed very early in the embryo. They are de- veloped in that portion of the primitive tissue called the mesoderm. The cells which are to form the vessels become extended into processes of varying length, which grow out from the cells in two or more directions. The cells become united with one another, either directly or by the junc- tion of their processes, so that an irregular network is thus formed. Fig. 134. - Isolated Capillary Network formed by the Junction of Several Hollowed-out Cells, and containing Coloured Blood-corpuscles in a Clear Fluid, p, p, pointed cell-processes extending in different directions for union with neighbouring capillaries. (Schafer.) Meanwhile the nuclei in the cells multiply, and each nucleus surrounds itself with a small amount of cell-protoplasm. The corpuscles thus formed acquire a reddish colour, and the protoplasmic network in which they lie becomes hollowed out into a system of branched canals containing fluid, in which the nucleated coloured corpuscles float. The protoplasmic walls of the vessels gradually change into the flattened cells which com- pose the walls of the capillaries, and which form the lining of the arteries and veins. The remaining coats of the larger vessels are developed later from other cells which apply themselves to the exterior of these tubes. The first white corpuscles do not appear in the vessels so early as the coloured ones. They probably occur in the beginning as free cells and wander in from the outside. The new vessels which form in the healing of wounds and in the restora- tion of lost parts are produced by a process which is essentially the same as above described. Blood-corpuscles, however, are not produced within them, but in bone marrow. The white corpuscles are undoubtedly pro- duced to a large extent in the lymph nodes and other lymphoid structures. Chap. XI] THE VASCULAR SYSTEM 197 SUMMARY GENERAL CIRCULATION Right auricle to right ventricle, then pulmonary arteries to lungs. Capillary system. Return by pulmonary veins to left auricle. Purpose - To obtain oxygen and get rid of carbon dioxide. Pulmonary Circulation Left auricle to left ventricle, then by means of aorta and its branches to all parts of the body. Capillary system. Re- turn by veins which empty into superior and inferior vense cavse. Systemic Circulation Carry and give up oxygen and nutritive mate- rial to tissues. Take carbon dioxide and other waste products from tissues. Purpose 1. Character of heart-beat Muscular condition. Nutrition. Factors Governing Circulation 2. Contraction and relaxation of minute arteries. Vaso constrictor' nerves. Vaso dilator nerves. 3. Elasticity and extensibility of the arteries - age. 4. Valves of the heart < Age. , Condition. Remittent, sudden, rapid. Elasticity of arteries produces a continuous stream in arterioles. Arteries Capillaries 1. Action of heart. 2. Elasticity of arteries. 3. Local nervous influences. 4. Condition of walls. Circulation in Blood-Vessels Slow steady flow dependent on Continuous, uninterrupted flow Faster than capillaries. Slower than arteries. Valves prevent backward flow. Veins Alternate contraction and expansion of artery Infant, 130 Three years, 100 Adult, 72. Old age, 65. Pulse Rate Higher in women than in men. PULSE Eating. Muscular activity. Mental excitement. Age. Sleep. Condition of health. Idiosyncrasies. Changes in Pulse Rate may be due to 198 ANATOMY FOR NURSES [Chap. XI Distention of arteries, capillaries, veins. Migration of white corpuscles. Exudation fluid - swelling. Diapedesis of red corpuscles. Stasis, or stagnation. Death of tissue or recovery. Inflammation . 1. Direct communication between right and left auricle by means of foramen ovale. 2. Direct communication between umbilical vein and in- ferior vena cava. Ductus venosus. 3. Direct communication between pulmonary artery and aorta. Ductus arteriosus. 4. Oxygen and nutritive susbtances obtained from placenta. Foetal Circulation CHAPTER XII VASCULAR SYSTEM CONCLUDED: LYMPH AND LYMPHATIC VESSELS. LYMPH NODES AND BODIES OF ALLIED STRUC- TURE. DUCTLESS GLANDS All the tissues1 of the body are traversed by a set of vessels called the capillaries. These capillaries form networks, the meshes of which differ in form and size in the different tissues. The meshes of these networks are occupied by the elements (cells or their products) of the tissues; and filling up such spaces as exist between the capillary walls and the elements of the tissue, is found a pale, straw-coloured liquid resembling in many re- spects the fluid portion of the blood, and called lymph. LYMPH Lymph is a pale, straw-coloured liquid that bathes all the tissue spaces of the body. It is slightly alkaline, has a salty taste, and no odour. When examined with the microscope, it is seen to consist of a clear liquid with corpuscles floating in it. The liquid part resembles the plasma of the blood in its com- position, except that it contains relatively more water and less solids. It clots when removed from the body, but more slowly and more feebly than blood. Sources of lymph. - During the passage of the blood through the thin-walled capillaries, the plasma is forced to transude into such spaces as exist between the cells of the tissues. In addition to this transudation it is necessary to assume an active secretory process on the part of the endothelial cells composing the capil- lary walls. This plasma plus the leucocytes that have left the vessels by emigration, make up the lymph proper. Besides the lymph proper, the lymph that fills the lacteals of the intestinal villi absorbs some of the products of digestion, especially the fats. 1 With the exception of the few mentioned in Chapter IX, page 146. 199 200 ANATOMY FOR NURSES [Chap. XII This portion of the lymph that has absorbed the fats is milky in appearance, and is called 11 chyle." The lymph, broadly speaking, is dilute blood minus its red corpuscles. The chyle is lymph plus a very large quantity of minutely divided fat. Functions of the lymph. - The lymph bathes all portions of the body not reached by the blood. Hence the lymph conveys the nutrient ingredients of the blood to all cells not directly bathed by the blood. It delivers to the cells the material each cell needs to maintain its functional activity, and picks up and returns to the blood the products of this activity, which products may be simple waste, or matters capable of being made use of by some other tissue. There is thus a continual interchange going on between the blood and the lymph. This interchange is effected in two ways: ■-- (1) By diffusion, or osmosis. - This process may be partially understood by the following illustration. If a tumbler be completely divided vertically into two com- partments by a moist piece of membrane, and a watery solution of common salt be placed in one compartment, and a watery solution of sugar in the other, it will be found after a time that some of the salt has found its way into the solution of sugar, and vice versa, some of the sugar into the salt solution. Such an interchange is said to be due to diffusion, and if the process were allowed to go on for some hours, the same proportion of salt and sugar would be found in the solutions on each side of the dividing membrane. So in the living body. The lymph becomes altered by the metabolic changes of the tissues which it bathes, and we have two different fluids, separated by the moist membrane which forms the walls of the blood-vessels, - the lymph in the tissues outside the walls of the capillaries and the blood inside the capillary walls, - and the same conditions may be said to exist as in the salt and sugar solutions just spoken of. And now the same phenomena take place; for though the pressure is higher in the blood-vessels than in the lymph outside, some of the constituents of the lymph pass into the blood by the process of osmosis. These constituents, which, as we cannot too often emphasize, are products resulting from the activity of the tissues, are carried away by the blood to other tissues, which will either make use Chap. XII] THE VASCULAR SYSTEM 201 of them, or, as in the kidneys, take them up to make excretory fluids, and so remove them. (2) By pressure changes. - The blood, on account of the higher pressure, loses more liquid to the lymph than it receives back by the process of osmosis. This excess lymph gathers up the waste materials of the cells surrounding the lymph spaces and through the medium of the lymphatics pours this waste into the blood, to be eliminated by the skin, lungs, and urine. In consequence of the different wants and wastes of different tissues at different times, both the lymph and blood must vary in composition in different parts of the body. But the loss and gain is so fairly balanced that the average composition is pretty constantly maintained. The chyle, or lymph of digestion, absorbs nutrient materials (mostly fat) from the intestines and pours this food into the blood current, to be distributed to all parts of the body. LYMPHATIC VESSELS As the process of transudation described on page 199 is con- tinual; it follows that oedema would result from the accumula- tion of lymph if some system of drainage were not provided. This drainage system is provided by the lymphatic vessels. The tiny spaces that exist between the cells that form the body tissues are called " lymph spaces." These lymph spaces form the mouths of microscopic lymph capillaries, and closely resemble the blood capillaries in structure. "It is still a question among the histologists whether the lymph vessels form a closed system or are in direct anatomical connection with the tissue spaces. Recent work supports the view that the lymph capillaries are closed vessels similar in structure to the blood capillaries. They end in the tissues generally, but are not in open communication with the spaces between the cellular elements or with the larger serous cavities between the folds of the peritoneum, pleura, etc." (Howell.) These lymph capillaries unite and form larger channels known as "lymphatics"; this latter arrangement is comparable to the formation of veins from blood capillaries. In fact, the plan upon which the lymphatics are constructed is almost identical with that of the venous system. The small 202 ANATOMY FOR NURSES [Chap. XII vessels unite and form larger vessels, and they finally converge into two main channels; (1) thoracic duct, and (2) right lym- phatic duct. The lymphatics may be divided into two sets: - 1. Lymphatics proper. 2. Lacteals. (1) The lymphatics proper drain off' the lymph from all parts of the body. (2) The lacteals are lymphat- ics that have their origin in the villi of the small intestine. During the period of intestinal digestion they are filled with chyle which has a white aspect, dependent upon the fatty par- ticles absorbed from the food, and suspended in it like oil globules in milk. After fast- ing, the lacteals contain lymph which differs very little from the lymph found in the ordi- nary lymphatics. These two sets of vessels are alike in their general structure. A close relationship exists between the lymphatics and the serous membranes proper. These closed sacs are to be regard- ed as prodigiously expanded lymph spaces. The true sto- mata of these serous mem- branes are connected with other lymph spaces. Structure of the lymph vessels. - The lymphatics resemble the veins in their structure as well as in their arrangement. The smallest have but a single coat of endothelioid cells, having a peculiar dentated outline. Fig. 135.-Lacteals and Lymphatics, during Digestion. (Collins.) Chap. XII] THE VASCULAR SYSTEM 203 The larger vessels have three coats, similar to veins, except that they are so thin as to be transparent, and they are more abun- dantly supplied with valves. The valves are constructed and arranged in the same fashion as those of the veins, but follow one another at such short intervals, that, when distended, they give the vessel a beaded or jointed appearance. They are usually wanting in the smaller networks. The valves allow the passage of material from the smaller to the larger lymphatics, and from these into the veins, and obstruct the flow of anything in the opposite direction. Flow of lymph. - The course of the liquid in the lymphatics is always from the periphery to the centre. The lymphatics do not cany to the tissues. Their office is to carry away from the tissues into the veins all the material the tissues do not need. The lymphatics from the right side of the head, neck, the right arm, and the upper part of the trunk, enter the right lymphatic duct. The vessels from the rest of the body, includ- ing the lacteals from the intestines, enter the thoracic duct. The parts drained by each are suggested by Figure 140. The lymph, like the blood in the veins, is returned from the limbs and viscera by a deep and by a superficial set of vessels. In their course from origin to termination most of the lymphatics pass through small masses of tis- sue, called lymph nodes, a description of which will be given later on. The thoracic duct. - The thoracic duct, from fifteen to eighteen inches (375 to 450 Fig. 136.-A Small Por- tion of a Lymphatic Plexus. L, L, L, L, Lymphatic vessel with characteristic endothe- lium. (Schafer.) Fig. 137.-Valves (Fiintj Lymphatics' 204 ANATOMY FOR NURSES [Chap. XII mm.) long in the adult, extends from the second lumbar verte- bra to the root of the neck. It lies in front of the bodies of the vertebrae gradually inclining towards the left until, when on a level with the seventh cervical vertebra, it turns outwards and BEEP CERVICAL NODE- PROPER AXILLARY NODES - EPICONDYLAR NODE -PALMAR PLEXUS Fig. 138.-The Nodes and Vessels of the Upper Limb. (Gerrish.) Chap. XII] THE VASCULAR SYSTEM 205 arches downwards and forwards to terminate in the innominate vein at the point of junction of the left inter- nal jugular and left subclavian. The size is usually compared to that of a goose-quill. It is dilated below, where it receives the lymphatics from the lower limbs and the chyle from the lacteals, the dilatation being known as the chyle cistern (receptaculum chyli). The duct is provided with valves, and in other respects closely resembles the larger lymphatics in structure. It is often alternately contracted and en- larged at irregular intervals. (See Fig. 131.) The right lymphatic duct. - The right lymphatic duct is a short vessel usually from one to one and one-half inches (25 to 38 mm.) in length. It pours its contents into the innominate vein at the junction of the right inter- nal jugular and subclavian veins. MOVEMENTS OF THE LYMPH The onward progress of the lymph from the tissues to the veins is main- tained chiefly by three things. (1) Differences in pressure. - The positive pressure in the lymph spaces as opposed to the zero, or negative pressure at the other end of the lymph channel, drives the lymph on. As we have already seen in our last chapter, the pressure exerted upon the blood in the capillaries is greater than that exerted upon the blood in the veins. This pressure in the smaller blood- vessels is communicated through the Fig. 139. - The Nodes and Vessels of the Lower Limb. (Gerrish.) Fig. 140.-The regions whose lymph flows into the right lymphatic duct are suggested by the darker area; those which are tributary to the thoracic duct by the lighter area. (Gerrish.) 206 Chap. XII] THE VASCULAR SYSTEM 207 blood-plasma to the lymph, and thus, though the lymph is not subjected to the same amount of pressure as the blood in the capillaries, it still stands at a higher pressure than the blood in the veins. We may consider the lymphatics to form a system of vessels leading from a region of higher pressure, viz. the lymph spaces of the tissues, to a region of lower pressure, viz. the interior of the large veins of the neck. (2) Muscular movements and valves. - The muscular move- ments of the body compress the lymphatics and force the lymph on in the proper direction. The numerous valves prevent a return flow in the wrong direction. (3) Thoracic aspiration. - During each inspiration the pres- sure on the thoracic duct is less than on the lymphatics outside the thorax, and the lymph is accordingly "sucked" into the duct. During the succeeding expiration the pressure on the thoracic duct is increased, and some of its contents, prevented by the valve from escaping below, are pressed out into the innominate veins. (Edema. - The lymph in the various lymph spaces of the body varies in amount from time to time, but under normal circum- stances, never exceeds certain limits. Under abnormal condi- tions, these limits may be exceeded, and the result is known as oedema, or dropsy. Similar excessive accumulations may also occur in the larger lymph spaces, the serous cavities. The possible causes of oedema are: - (1) An obstruction to the flow of lymph from the lymph spaces. (2) An excessive transudation, the lymph gathering in the lymph spaces faster than it can be carried away by a normal flow. (Edema is almost always due to the latter cause, viz. excessive transudation. The inflammatory oedema, due to changes in the walls of the blood-vessels, we have already touched on in speaking of the capillary circulation. In this kind of oedema the transudation is, besides being crowded with migrating corpuscles, more dis- tinctly coagulable than ordinary lymph. Allied to this inflam- matory oedema is the "effusion," which appears in the serous cavities when they are inflamed, as in pleurisy and peritonitis. 208 ANATOMY FOR NURSES [Chap. XII The lymph nodes are numerous round or ovoid bodies placed in the course of the lymphatics. They vary in size from a pin- head to an almond. A lymph node is covered by an envelope, or capsule, of con- nective and muscular tissue. This capsule sends fibrous bands called trabeculae ("little beams") into the substance of the node, and divides it into irregular spaces, which com- municate freely with each other. The irregular spaces are occupied by a mass of cellular pulp substance, which, however, does not quite fill them as it never touches the capsule or trabeculae, but leaves a narrow interval between itself and them. It looks as if the pulp had originally filled the framework and then shrunk away slightly on all sides. The spaces thus left form channels for the passage of the lymph, which enters by afferent vessels, and after circulat- ing through the node, issues by effer- ent vessels. Lymph nodes are well supplied with blood. A lymph node is comparable to a sponge placed in a snugly fitting rubber bag. The rub- ber bag connects on one side with a rubber tube representing the afferent lymph vessel, and from the opposite side there leads away from the rubber bag another tube representing the efferent lymph vessel. The rubber bag is the representative of the capsule of the node, the meshwork of the sponge is comparable to the framework of the node, and the holes in the sponge to the open channels. The substance of a lymph node is reticular adenoid tissue. Lymph nodes are found in great numbers in the neck, thorax, axilla, groin, mesentery and alongside of the aorta, vena cava inferior, and the iliac vessels. A few are found LYMPH NODES Fig. 141.- A Lymph Node with its Afferent and Effer- ent Vessels. (Gerrish.) Chap. XII] THE VASCULAR SYSTEM 209 in the popliteal space and in the arm as far as the elbow, but none farther down the leg or forearm. They are usu- ally named from the position in which they are found in the body, viz. cervical in the neck, thoracic in the thorax, axillary in the axilla, inguinal in the groin, mesenteric in the mesentery. Purpose of lymph nodes. - The lymph nodes serve two im- portant purposes. (1) As filters for the lymph. - In this way they act as safety- valves and serve to retard the spread of infection through the Fig. 142.-The Lymph Nodes of the Neck and Upper Part of the Thorax. (Gerrish.) body. If any portion of the body is infected, the poison may be carried by the lymphatics to their special nodes. There its course is stopped and the node may suffer enlargement or even 210 ANATOMY FOR NURSES [Chap. XII break down and be destroyed. If the infection is not arrested, the node next in line will suffer, then the next,1 and so on. (2) Multiplication of leucocytes. - In its passage through the node the lymph takes up fresh leucocytes, which are continually multiplying by cell division in the glandular substance. I MUCOUS > COAT' PLANE OP MUCOUS- SURFACE GLAND - MUSCULARIS - MUCOS/D \ AREOLA Ji > COAT muscular > COAT Fig. 143. - Mucosa of Small Intestine in Ideal Vertical Cross-section. (Gerrisli.) Solitary lymph nodules. - Closely connected with the lym- phatic vessels in the walls of the intestines are small, rounded bodies of the size of a small pin's head, called solitary lymph nodules. These bodies consist of a rounded mass of fine lym- phoid tissue, the meshes of which are crowded with leucocytes. Into this mass of tissue one or more small arteries enter and form a capillary network, from which the blood is carried away by one or more small veins. Surrounding the mass are lymph channels which are continuous with the lymphatic vessels in the tissue below. Aggregated lymph nodules of Peyer. - They are simply col- lections of lymph nodules. A well-formed Peyer's patch consists 1 The transmission of disease from one organ to another by means of the lymphatics (or otherwise) is called "Metastasis." Chap. XII] THE VASCULAR SYSTEM 211 of fifty or more of these solitary lymph nodules, arranged in a single layer, close under the epithelium of the intestinal mucous membrane, and stretching well down into the tissue beneath. These patches are circular or oval in shape, from one-half to three inches (12.5-75 mm.) long, and one-half inch (12.5 mm.) wide, and from twenty to thirty, in number. They are largest and most numerous in the portion of the intestine called the ileum. They increase in size during digestion. These Peyer's patches are the seat of local inflammation and ulceration in typhoid fever. Tonsils. - The tonsils are flat- tened ovoid bodies, placed on each side of the throat in the tri- angular space between the palatine arches. 'They consist of a collection of lymph nodules held together by a distinct capsule and covered on their exposed surface by mucous membrane. Their surfaces are pitted with apertures which lead into mucous glands. (See Fig. 156.) DUCTLESS GLANDS The thyroid and other glands of similar structure are classed as ductless glands because they have no special duct by which their secretion is discharged. It has been proven that some of these glands form substances out of materials brought to them in the circulation and discharge these substances into the blood. It is probable that all ductless glands have a similar office. They are well supplied with lymphatics and blood-vessels, and whatever secretion 1 or excretion they produce is carried in these vessels. The most important ductless glands are: - (1) Spleen. (2) Thyroid body. (3) Parathyroids. Fig. 144. - Aggregated Lymph Nodule (Peyer's Patch). (Gerrish.) 1 See " Internal Secretion," page 130, Chapter VII. 212 ANATOMY FOR NURSES [Chap. XII (4) Thymus. (5) Supra-renal capsules. (6) Hypophysis. (7) Carotid glands. (8) Coccygeal glands. (1) Spleen. - The spleen is the largest of the ductless glands. It is directly beneath the diaphragm, in the epigastric and left hypochondriac regions and behind the stomach. It is covered by a portion of the peritoneum, the serous membrane covering the viscera of the abdo- men. It is oval in shape, convex on the outer sur- face, concave on the inner, and weighs usually from five to eight ounces (150 to 240 grammes). Beneath the serous coat it is covered by a fibrous and muscular capsule which sends fibrous bands (trabecules) to form a network in the interior of the organ. In the meshes of the fibrous framework lies a soft pulpy substance containing a large amount of blood and therefore of a deep red colour. This soft red pulp is dotted with whitish specks, which are small masses of lymphoid tissue, and are called the Malpighian corpuscles of the spleen. Blood is supplied to the spleen by the splenic artery, which enters the concave side of the spleen at a depression called the hilus. The arrangement of the blood-vessels is peculiar to this organ. The splenic artery divides into several branches before entering the organ, and after entering, rapidly divides into smaller vessels. When the minute arteriole stage is reached, the vessels Fig. 145. - The Spleen, showing the Gastric and Renal Surfaces and the Blood-vessels. (Gerrish.) Chap. XII] THE VASCULAR SYSTEM 213 terminate, and the blood escapes into the spleen pulp. It is conveyed from the gland by thin-walled veins. The pulp con- tains numerous red corpuscles, and many bodies which appear to be red corpuscles in process of decay or destruction, and it is surmised that the disintegration of worn-out red corpuscles is one function of the spleen. The Malpighian corpuscles are fac- tories for leucocytes, and the blood leaving the spleen by the splenic vein is rich in leucocytes. The spleen varies in size at different periods of life, is relatively large in childhood, and atrophies in old age. The size is increased during and after digestion, and is always large in well-fed, and PYRAMID OF thyroid body right lobe of. thyroid body Fig. 146. -The Thyroid Body and the Related Blood-vessels. (Gerrish.) small in starved, animals. In certain diseases, more especially typhoid and malaria, a temporary enlargement takes place. In prolonged or chronic malaria, a permanent enlargement of the spleen occurs, and forms the so-called "ague cake." (2) The thyroid body. - The thyroid body is a small, flat gland lying against the fore part of the trachea, below the 214 ANATOMY FOR NURSES [Chap. XII thyroid cartilage. It is of a deep red colour, weighs about an ounce (30 grammes) or more, and consists of two lateral lobes connected at their lower parts by an isthmus. The lobes are broadest below and taper to a point above. Comparatively little is known about the functions of the thyroid, but enlarge- ment of it constitutes goitre, which is said to be frequent in certain countries where the drinking water contains lime. Con- genital defects of the thyroid produce the condition known as cretinism. Atrophy of the thyroid causes the peculiar disease called myxoedema. Graves's disease (exophthalmic goitre) is characterized by an enlargement of the thyroid, together with protrusion of the eyes and frequent heart action. It is supposed to be due to an excessive amount of thyroid secretion. (3) The parathyroids. - Embedded in the surface of each lateral lobe of the thyroid body are two little masses, each about one-fourth inch (6.25 mm.) in diameter. They are solid accu- Fig. 147. - The Thymus, the Sternal and Costal Cartilages having been Removed. (Gerrish.) mulations of epithelioid cells, invested with a tunic of areolar tissue and well supplied with blood-vessels. The function of the parathyroids is supposed to consist in neutralizing toxic substances found elsewhere in the body. Chap. XII] THE VASCULAR SYSTEM 215 (4) The thymus body. - The thymus is a temporary organ of foetal and infantile life. It is situated below the thyroid and in front of the trachea. It appears at the end of the second month of intra-uterine life and continues to grow until a child is two or three years old. At that time it weighs about six drachms. Thereafter it atrophies and disappears, except for some shreds of tissue still present at the age of puberty. (5) The supra-renal capsules (adrenals). - Lying immediately above each kidney are two small, flattened bodies of a yellowish colour. They are usually classified with the ductless glands, as they have no excretory duct, but are sometimes classed with the organs of the central nervous system, as they contain a great deal of fibrous and cellular nerve-tissue. Each organ weighs about one drachm, and is invested by a fibrous capsule which sends fibres into the glandular substance; these fibres form a frame- work for the soft, pulpy substance of the gland, and within the spaces of the framework are groups of cells. (See Fig. 169.) Recent experiments have demonstrated: -- (a) A close connection between the supra-renal capsules and the central nervous system. (5) That the gland is the seat of an important internal secre- tion called adrenalin, which has a marked stimulating effect upon the tone of the blood-vessels and the heart. The supra-renal capsules are plentifully supplied with blood- vessels and lymphatics, and they contain some striking colour- ing matters. In diseases of these organs, the skin frequently becomes "bronzed" from an increase of pigment or colouring matter. (6) The hypophysis. - The hypophysis, also called the pitui- tary body, is of an ovoid form, a reddish gray colour, and weighs from five to ten grains. It is lodged in a depression of the middle portion of the sphenoid bone, and is firmly held in place by the dura mater. Little is known of the function of this gland, but that there is some relation between the pituitary body and acromegaly, or gigantism, there can be no doubt. Disease of the pituitary body in adult life is attended with enlargement of the bones of the extremities and the features of the face, a condition known as acromegaly. When the disease occurs in early life, as development progresses, there is a condition known as gigantism. 216 ANATOMY FOR NURSES [Chap. XII (7) The carotid glands. - They are so 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. They are covered by a fibrous capsule. (8) Coccygeal gland. - The coccygeal gland is a small mass about one-tenth inch (2.5 mm.) in diameter, situated in front of the tip of the coccyx. It is covered by fibrous tissue and com- posed of epithelial cells. The carotid and coccygeal glands are so small that they often escape detection even in the most care- ful autopsies. SUMMARY Pale straw-coloured fluid. Alkaline reaction. Salty taste. No odour. Consists of blood plasma (forced to transude through capillary walls) plus leucocytes. Description Lymph acts as middleman between the blood and the tissues. Carries nourishment from blood to tissues. Carries waste from tissues to blood. LYMPH | Function. . Dependent upon [ 1. Osmosis. । 2. Pressure changes. [ 3. Lymphatic vessels. Chyle . . . { Lymph plus nutrient material, mostly fats. Lymph capillaries. Lymphatics. Lacteals. Serous sacs. Thoracic duct. Right lymphatic duct. Lymph nodes. Lymphatic System ' Origin in lymph spaces between cells of tissue. Start as microscopic lymph capillaries, unite to form lynr phatics. Comparable to formation of veins. Lymph capillaries - one coat of endothelium - dentated. Lymphatics - three coats - numerous valves. Drain off lymph from all parts of the body. Lymphatics Lymphatics of the intestines. Many originate in villi of small intestine. Cnntm-n -I During digestion - chyle. / During fasting - lymph. Absorb fatty substances. Lacteals . Chap. XII] THE VASCULAR SYSTEM 217 Expanded lymph spaces. Communicate by means of stomata with other lymph spaces. Serous Sacs 15 to 18 in. long. Size of goose-quill. In front of vertebra from 2d lumbar to 7th cervical. Ilas three coats - numerous valves. Dilatation at lower portion called " chyle cistern." Receives lymph from left side, of head, neck, and chest, left arm, all of abdomen, and both lower limbs. Receives chyle from lacteals. Pours lymph and chyle into left innominate vein. Thoracic Duct 1 to 1| in. long. Receives lymph from right side of head, neck, and chest, also right arm. Pours lymph into right innominate vein. Right Lymphatic Duct Movements of Lymph Maintained by 1. Differences in pressure. 2. Muscular movements and valves. 3. Thoracic aspiration. Accumulation of lymph in tissues. (Edema Caused by rl. Obstruction to flow of lymph from tissues, 2. Excessive transudation. Round. Ovoid. Shape Size varies from pinhead to almond. ~ . f Connective tissue. Consists of outer capsule 1 . [ Muscular tissue. Interior divided into irregular spaces like sponge. Spaces partially filled with reticular adenoid tissue. Communicating channels for lymph, which enters by afferent, leaves by efferent, vessels. Are well supplied with blood. Description LYMPH NODES Neck, thorax, axilla, groin, mesentery. Alongside of great vessels of trunk. In the arms as far as elbows. In the legs as far as popliteal space. Usually name indicates location. Location . „ _ Function . 1. Filters - preventive and protective. 2. Multiplication of leucocytes. 1. Solitary lymph nodules found in intestines. 2. Aggregated lymph nodules of Peyer - fifty or more soli- tary lymph nodules form so-called patches in small intestine. 3. Tonsils - collections of lymph nodules occupy triangular space between palatine arches on either side of throat. Special Lymph Nodules 218 ANATOMY FOR NURSES [Chap. XII Spleen. Thyroid body. Parathyroids. Thymus. Supra-renal capsules. Hypophysis. Carotid. Coccygeal. Ductless Glands Largest of ductless glands. Beneath diaphragm, behind and to the left of the stomach. Consists of a fibrous network filled with a vascular pulp, enclosed in a fibrous and muscular capsule which is covered by serous ryembrane. Blood supply peculiar - arteries, veins. SPLEEN Description 'Not definitely known. Function Presumably r Disintegration of red blood-cells. Manufacturing leucocytes. L Production of an internal secretion. 'Small gland. Weighs about one ounce. Consists of two lobes connected by an isthmus. Placed in front of trachea, below thyroid cartilage. -Function not definitely known. Thyroid . 'Four small masses, each about | in. diameter. Two are embedded in each lobe of thyroid. . Consist of epithelioid cells, invested with areolar tissue. Parathyroids Temporary organ. Appears at 2d month of intra-uterine life, grows until child is two or three years of age, and it weighs about six drachms. Then atrophies steadily until age of puberty, when only some shreds of tissue . are left. Thymus . Small glands lying above each kidney. Weigh one drachm. Consist of a fibrous framework, the spaces of which are filled with groups of cells. They are enclosed in a fibrous capsule and are well supplied with blood-vessels, lymphatics, and nerves. Internal secretion - adrenalin. Supra-renal Capsules Hypophysis or Pituitary Gland Small reddish gray gland, weighs 5-10 grains. Function not positively known. Carotid Glands Small glands, one situated in bifurcation of each carotid artery. Coccygeal Gland Small gland inch in diameter, situated in front of tip of coccyx. CHAPTER XIII THE RESPIRATORY APPARATUS: LARYNX; TRACHEA; BRONCHI AND LUNGS. -RESPIRATION. THE EFFECT OF THE FIRST RESPIRATIONS. -CAPACITY OF THE LUNGS. -THE EFFECT OF RESPIRATION UPON THE AIR OUTSIDE THE BODY, UPON THE BLOOD. -MODIFIED RESPIRATORY MOVEMENTS THE RESPIRATORY APPARATUS Respiration is the main process by means of which the body is supplied with oxygen and relieved of carbon dioxide. Other waste products are also partly eliminated by the act of expiration. A respiratory apparatus consists essentially of a moist and permeable membrane, with blood-vessels containing carbon Al R THIN MUCOSA CAPILLARY BLOOD VESSEL Fig. 148. - Diagram of the Essentials of a Respiratory Apparatus. (Gerrish.) ' dioxide on one side, and air or fluid containing oxgyen on the other. In most aquatic animals the respiratory organs are external in the form of gills; in terrestrial, or air-breathing ani- mals, the respiratory organs are situated internally in the form of lungs, and are placed in communication with the external air by a tube or windpipe. In man, the respiratory apparatus may be conveniently divided into - 1. Larynx. 2. Trachea. 3. Bronchi. 4. Lungs. 219 220 ANATOMY FOR NURSES [Chap. XIII THE LARYNX The larynx is situated between the base of the tongue and the top of the trachea, in the upper and front part of the neck. Above and behind lies the pharynx, which opens into the oesoph- agus, or gullet, and on either side of it lie the great vessels of the neck. In form, the larynx is narrow and rounded below where it blends with the trachea, but broad above and shaped somewhat like a triangular box, with flat sides and prominent ridge in front. It is made up of nine pieces of cartilage, united together by ligaments, and moved by numerous muscles. The three principal cartilages are the cricoid, thyroid, and epiglottis. The cricoid resembles a ring with the hoop part in INFERIOR VOCAL FOLD \SUPERIOR VOCAL FOLD Fig. 149. - Larynx. Viewed from above. (Gerrish.) front and the signet part in the back. The thyroid resembles a shield and is the largest. It rests upon the cricoid and con- sists of two square plates, or ala? (right and left), which are joined together in front and form by their union the laryngeal prominence (Adam's apple). The upper portion of the hind border of the thyroid is called the superior horn, and the lower portion the inferior horn (cornu, see Fig. 151). The epiglottic cartilage, or epiglottis, is shaped like a leaf. The stem is in- serted in the notch between the two plates of the thyroid. The larynx is lined throughout by mucous membrane, which is con- Chap. XIII] RESPIRATION 221 tinuous above with that lining the pharynx, and below with that lining the trachea. The glottis. - Across the middle of the larynx is a transverse partition, formed by two folds of the lining mucous membrane, stretching from side to side, but not quite meeting in the middle line. They thus leave in the middle line a chink, or slit, running from front to back, called the glottis, or rima glottidis. The vocal folds (cords). - Embedded in the mucous mem- branes at the edges of the slit are fibrous and elastic ligaments, which strengthen the edges of the glottis and give them elastic- ity. These ligamen- tous bands, covered with mucous mem- brane, are firmly at- tached at either end to the cartilages of the larynx, and are called the vocal folds (cords). The space left between their edges, the glottis, varies in shape and size, according to the action of the muscles upon the laryngeal walls. When the larynx is at rest during quiet breathing, the glottis is V-shaped; during a deep inspiration it becomes almost round, while during the production of a high note the edges of the folds approximate so closely as to leave scarcely any open- ing at all. The glottis is protected by the leaf-shaped lid of fibro-cartilage, called the epiglottis, which shuts down upon the Fig. 150.-The Larynx as seen by Means of the Laryngoscope in Different Conditions of the Glottis. A, while singing a high note; B, in quiet breathing; C, during a deep inspiration. I, base of tongue; e, upper free edge of epiglottis; e', cushion of the epiglottis; ph, part of anterior wall of pharynx; cv, the true vocal folds; cvs, the false vocal folds; tr, the trachea with its rings; b, the two bronchi at their commencement. 222 ANATOMY FOR NURSES [Chap. XIII opening during the passage of food or other matters into the oesophagus. Voice. - The vocal folds produce the voice. A blast of air, driven by an expiratory movement out of the lungs, throws the Fig. 151. - Front View of Cartilages of Larynx. Trachea and Bronchi two elastic folds into vibrations. These impart their vibrations to the column of air above them, and so give rise to the sound which we call the voice. Chap. XIII] RESPIRATION 223 The larynx is placed in communication with the external air by two channels: the one, supplied by the nasal passages, is always open; the other, furnished by the mouth, can be opened and closed at will. Under normal conditions breathing should take place through the nasal route only, and the nasal passages, being narrow, thickly lined, and freely supplied with blood- vessels, can, even in the very coldest weather, warm the air before it reaches the lungs. THE TRACHEA The trachea, or windpipe, is a fibrous and muscular tube. It measures about four and a half inches (112 mm.) in length, and three-quarters .of an inch (19 mm.) from side to side. It extends down into the thorax from the lower part of the larynx to opposite the third thoracic vertebra, where it divides into two tubes, - the two bronchi, - one for each lung. The walls are strengthened and rendered more rigid by hoops of cartilage embedded in the fibrous tissue. These hoops are C-shaped and incomplete behind, the cartilaginous rings being completed by bands of plain muscular tissue where the trachea comes in contact with the oesophagus. Like the larynx, it is lined by mucous membrane, and has a ciliated epithelium upon its inner surface. The mucous membrane, which also extends into the bronchial tubes, keeps the internal surface of the air- passages free from impurities; the sticky mucus entangles par- ticles of dust and other matters breathed in with the air, and the incessant movements of the cilia continually sweep this dirt- ladened mucus upwards and outwards. THE BRONCHI The two bronchi, into which the trachea divides, enter the right and left lung respectively, and then break up into a great number of smaller branches which are called the bronchial tubes, or bronchioles. The two bronchi, resemble the trachea in structure; but as the bronchial tubes divide and subdivide, their walls become thinner, the small plates of cartilage cease, the fibrous tissue disappears, and the finer tubes are composed of only a thin layer of muscular and elastic tissue lined by mucous membrane. 224 ANATOMY FOR NURSES [Chap. XIII RIGHT LUNG LEFT LUN-G Fig. 152. - Bronchi and Bronchioles. The lungs have been widely separated and tissue cut away to expose the air-tubes. (Gerrish.) THE LUNGS The two lungs are cone-shaped organs with concave bases to fit over the convex portion of diaphragm. They occupy almost all the cavity of the thorax which is not taken up by the heart. The right lung is the larger and heavier; it is broader than the left, owing to the inclination of the heart to the left side; it is also shorter by one inch, in consequence of the diaphragm rising higher on the right side to accommodate the liver. The right lung is divided by fissures into three lobes, upper, middle, and lower. The left lung is smaller, narrower, and longer than the right, and has only two lobes, upper and lower. . Pleura. - Each lung is enclosed in a serous sac, the pleura, one layer of which is closely adherent to the walls of the chest and diaphragm (parietal); the other closely covers the lung (visceral). The two layers of the pleural sacs, moistened by serum, are normally in close contact; they move easily upon one another, and prevent the friction that would otherwise Fig. 153. - Diagram of a Lobule of the Lung. A bronchiole is seen divid- ing 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 infundibula, the alveoli of which present their outer surfaces. Next are three infundibula in ver- tical section, the alveoli of each opening into the common passageway. In the next group the first infundibulum shows a pulmonary arteriole surrounding the opening of each alveolus, and the second gives the same with the addition of the close capillary network in the wall of each alveolus. 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. 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. (Gerrish.) 225 226 ANATOMY FOR NURSES [Chap. XIII occur between the lungs and the walls of the chest with every respiration. Anatomy of the lungs. - The lungs are hollow, rather spongy organs, and consist of the bronchial tubes and their terminal dilatations, numerous blood-vessels, lymphatics, nerves, and an abundance of fine, elastic connective tissue, binding all together. (See Fig. 103.) Each lobe of the lung is composed of many lobules, and into each lobule a branchiole enters and terminates in an enlargement having more or less the shape of a funnel, and called an infundibulum. From each infundibulum there is a series of finger-like projections known as alveoli, the walls of which are honeycombed with cavities called the air-cells. In this way the amount of surface exposed to the air and covered by the capillaries is immensely increased. Blood-vessels of the lungs. - Two sets of vessels are distrib- uted to the lungs: (1) the branches of the pulmonary artery, and (2) the branches of the bronchial arteries. (1) The branches of the pulmonary artery accompany the bronchial tubes and form a plexus of capillaries around the al- veoli. The walls of the bronchioles consist of a single layer of flattened epithelioid cells, surrounded by a fine, elastic connec- tive tissue and are exceedingly thin and delicate. Immediately beneath the layer of flat cells, and lodged in the elastic connective tissue, is this very close plexus of capillary blood-vessels; and the air reaching the alveoli by the bronchial tubes is separated from the blood in the capillaries by only the thin membranes forming their respective walls. The pulmonary veins begin at the margin of the alveoli and return the blood distributed by the pulmonary artery. (2) The branches of the bronchial arteries supply blood to the lung substance, - the bronchial tubes, coats of the blood- vessels, the lymph nodes, and the pleura. The bronchial veins return the blood distributed by the bronchial arteries. Speaking roughly, the lungs may be said to consist of a film- like elastic membrane covered by a close network of blood-vessels. The membrane is arranged in the form of irregularly dilated pouches at the end of fine tubes. These tubes open into larger and larger tubes, and finally into the windpipe, which places them in communication with the external air. Chap. XIII] RESPIRATION 227 By virtue of their structure, the large bronchial tubes remain permanently open; the smaller tubes, however, are subject to collapse when empty; they also may contract under certain nervous influences. The terminal dilatations are eminently elastic, and continually expand and contract; they are bathed with lymph, and are always moist. RESPIRATION The process of taking air into the lungs is known as inspiration, that of expelling it as expiration. An inspiration and an expira- tion make a respiration. During inspiration the cavity of the chest is enlarged in all three diameters : (1) antero-posterior, (2) lateral, and (3) vertical. This is brought about by the action of the intercostal and other muscles, which elevate the ribs and thereby increase the antero-posterior and lateral diameters. The descent of the diaphragm increases the vertical diameter. The lungs are correspondingly distended to fill the enlarged cavity. To prevent a vacuum in the lungs, air rushes in by way of the trachea to the bronchi. Upon the relaxation of the inspiratory muscles, the elasticity of the lungs and the weight and elasticity of the chest walls causes the chest to return to its original size, in consequence of which the air is expelled from the lungs. As in the heart, the auricular systole, the ventricular systole, and then a pause follow in regular order, so in the lungs the in- spiration, the expiration, and then a pause succeed one another. Frequency of respiration. - Each respiratory act in the adult is ordinarily repeated about eighteen times per minute. But this rate varies under different circumstances, one of the most important of which is age. The average rate in the newly born infant has been found to be forty-four per minute, and at the age of five years, twenty-six per minute. It is reduced between the ages of fifteen and twenty to the normal standard. The ratio to the pulse is about 1 to 4 in health. A condition of rest or activity readily influences the number of respirations per minute. They are always less frequent during sleep, and are markedly increased by severe muscular exercise. Respiration is an involuntary act. It is possible for a short time to increase or retard the rate of respiration within certain limits by voluntary effort, but this cannot be done continuously. 228 ANATOMY FOR NURSES [Chap. XIII If we intentionally arrest the breathing or diminish its frequency, after a short time the nervous impulse becomes too strong to be controlled, and the movements will recommence as usual. If, on the other hand, we purposely accelerate respiration to any great degree, the exertion soon becomes too fatiguing for con- tinuance, and the movements return to their normal standard. The nervous impulses which cause the contractions of the respiratory muscles arise in the medulla oblongata, travel down the spinal cord, and out along the phrenic and intercostal nerves. If the portion of the medulla oblongata where these nervous impulses arise be removed or injured, respiration ceases, and death at once ensues. This part of the medulla is known as the respiratory centre. The effect of the first respirations. - At birth the lungs con- tain no air. The walls of the air-sacs are in close contact, and the walls of the smaller bronchial tubes, or bronchioles, collapsed and touching one another. The trachea and larger bronchial tubes are open, but contain fluid and not air. When the chest expands with the first breath taken, the inspired air has to over- come the adhesions existing between the walls of the bronchioles and air-sacs. The force of this first inspiratory effort, spent in opening out and unfolding, as it were, the inner recesses of the lungs, is considerable. In the succeeding expiration, most of the air introduced by the first inspiration remains in the lungs, suc- ceeding breaths unfold the lungs more and more, until finally the air-sacs and bronchioles are all opened up and filled with air. The lungs thus once filled with air are never completely emptied again until after death. Capacity of the lungs. - As the lungs are not emptied at each expiration, neither are they filled. If filled to their ut- most, they can hold a little more than one gallon (4500 c.c.) of air. This total is divided as follows: - (1) Residual air. (2) Tidal air. (3) Reserve air. (4) Complementary air. Residual air is the air remaining in the lungs after the most powerful expiration. Tidal air is the air introduced with every ordinary inspira- tion. Chap. XIII] RESPIRATION 229 Reserve air is the amount of air in addition to the tidal air one can expel from the lungs in a forced expiration. Complementary air is the excess over the tidal air which may be introduced during a forced inspiration. Into the old or residual and reserve air fresh or tidal air is introduced with every inspiration. This tidal air gives up its oxygen to and takes carbon dioxide from the residual and reserve air. Thus the residual and reserve air transact the business of respiration, receiving, on the one hand, constant supplies of oxygen from the tidal air which it delivers to the blood in the capillaries in the walls of the alveoli and air-cells; and, on the other hand, returning, in exchange to the tidal air, the carbon dioxide it has received from the blood in these capillaries. The vital capacity is the sum of the tidal, complementary, and reserve airs added together. It equals about 225 cubic inches (3700 c.c.). Respiratory sounds. - The entry and exit of the air, are ac- companied by respiratory sounds or murmurs. These murmurs differ as the air passes through the trachea, the larger bronchial tubes, and the bronchioles. They are variously modified in lung disease, and are then often spoken of under the name of "rales." In laboured breathing the contraction of the respiratory muscles not usually brought into play, such as the muscles of the throat and nostrils, becomes very marked. The effects of respiration upon the air outside the body. - With every inspiration a well-grown man takes into his lungs about 30 cubic inches (500 c.c.) of air. The air he takes in differs from the air he gives out mainly in three particulars: - 1. Whatever the temperature of the external air, the expired air is nearly as hot as the blood; namely, of a temperature be- tween 98° and 100° F. (36.7° and 37.8° C.). 2. However dry the external air may be, the expired air is quite, or nearly, saturated with moisture.1 3. The air when breathed loses about one-fifth of its oxygen 1 This moisture evaporates from the blood. It is thought by some authorities that most of the moisture is collected by the breath from the mucous membrane of the respiratory tract. A certain quantity, however, evaporates from the blood through the walls of the capillaries, and, escaping with carbon dioxide through the membrane of the alveoli, is carried upwards in every expiration. 230 ANATOM T FOR NURSES [Chap. XIII and increases the carbon dioxide an hundred fold, the quantity of nitrogen suffering but little change. To be exact, the oxygen drops from 20.96 per cent to 16.40 per cent, whereas the carbon dioxide increases from 0.04 per cent to 4.41 per cent. Thus:-■ Oxygen Nitrogen Carbon Dioxide Inspired air contains 20.96 79.00 0.04 Expired air contains 16.40 79.19 4.41 4.56 loss .19 gain 4.37 gain (Notter and Firth.) In addition, the expired air contains a certain amount of effete matter of a highly decomposable and impure character. The quantity of water given off in twenty-four hours varies 1 very much, but may be taken on the average to be about ten ounces (293 c.c.). The quantity of carbon given off at the same time is pretty nearly estimated by a piece of pure charcoal weighing eight ounces (240 grammes). (Kirkes's.) If a man breathing eighteen times a minute takes in 30 cubic inches (500 c.c.) of air with each breath, it follows that in twenty-four hours 450 cubic feet2 (12.8 c.m.) of air will have passed through his lungs. And if such a man be shut up in a close room measuring seven and three-quarters feet (2.3 m.) each way, all the air in the room will have passed through his lungs in twenty-four hours. This is only theoretically true, for the man would have died from poisoning by the noxious waste material long before he had actually breathed every par- ticle of air in the room. Since at every breath the external air loses oxygen and gains carbon dioxide and other waste and poisonous matters, it is imperative that some provision be made for constantly renewing the atmospheric surroundings of people in dwelling-houses. This is accomplished by ventilation, which consists of a system of mechanical contrivances by means of which foul air is constantly- removed and fresh air as constantly supplied. The minimum amount of air-space each individual should have 1 Amount of water varies with temperature, size, and activity of individ- ual. 2 18 Resp. X 30 cu. in. per resp. = 540 cu. in. 540 cu. in. X 60 min. per hour = 32,400 cu. in. per hour. 32,400 cu. in. X 24 hr. per day = 777,600 cu. in. 777,600 cu. in. 4- 1728 = 450 cu. ft. Chap. XIII] RESPIRATION 231 to himself is 1000 cubic feet (28.3 c.m.). A room 10 feet high, wide, and long contains 1000 cubic feet (28.3 c.m.) and this space should be accessible by direct or indirect channels to pure air. For mixed communities 3000 cubic feet of air per hour is the accepted standard allowance per person. The amount for adult males is 3600 cubic feet per hour, and this gives us one cubic foot per second, an easy rule to remember. The size of the room is of importance only in so far as it necessitates a frequent change of air. Thus, a space of 1000 cubic feet must have the air changed three times an hour. This is about as often as a complete change of air can be effected without causing a draft. From 1000 to 1200 cubic feet should be the minimum allowance for the initial air-space. This is far more than most people are able to have, but it should be recognized as what all should have. The minimum amount of fresh air for hospitals ought to exceed that required in health, if 3000 cubic feet be admitted in health, 4000 cubic feet in sickness, and more, if possible to obtain. If the air is to be changed three times per hour, the cubic air-space should be about 1300 cubic feet, and the minimum of floor space not less than A, or about 110 square feet. (Notter and Firth.) Effects of respiration, upon the blood. - While the air in passing into and out of the lungs is robbed of a portion of its oxygen and loaded with a certain quantity of carbon dioxide, the blood as it streams along the pulmonary capillaries is also undergoing im- portant changes. As it leaves the right ventricle (by means o.' the pulmonary artery), it is venous blood of a dark crimson colour; when it enters the left auricle (by means of the pulmonary veins), it is arterial blood and of a bright scarlet colour. In pass- ing through the capillaries of the body from the left ventricle to the right auricle it is again changed from the arterial to the venous condition. The question arises, how is this change of colour effected? As we have already seen, the blood in the thin-walled, close- set pulmonary capillaries is separated from the air in the air- sacs by only the moist, delicate membranes which form their respective walls. By diffusion the oxygen in the air passes through these moist membranes into the venous blood in the pulmonary capillaries, combines with the reduced haemoglobin which has lost its oxygen in the tissues, and turns it into oxyhae- moglobin; the crimson colour shifts immediately into scarlet, 232 ANATOMY FOR NURSES [Chap. XIII and the red corpuscles hasten onwards to carry the oxyhaemo- globin to the tissues. Passing from the left ventricle to the capillaries in the tissues, the oxyhaemoglobin gives up some of its oxygen, the colour shifts back again to a crimson hue, and the red corpuscles return with this reduced haemoglobin to the lungs. The oxygen given up by the blood readily combines with the unstable chemical compounds of which the tissues are composed. In - this process, called oxidation,1 complex bodies are broken up into simpler ones, such as carbon dioxide and water, and there is thus liberated a great deal of energy, which is mani- fested in the increasing of muscular activity and in the pro- duction of heat. The carbon dioxide passes by diffusion into the venous blood, and is carried by it to the right side of the heart and thence to the lungs, a certain quantity, however, escaping from the blood through the kidneys and skin. A small and insignificant amount of oxygen is introduced into the blood through the skin, and with the food through the alimentary canal; but, as we have stated in the beginning of this chapter, respiration is the main process by means of which the body is supplied with oxygen and relieved of carbon dioxide. Intimate connection of respiration and circulation. - The respiration and circulation are profoundly and intimately con- nected, any change in the blood immediately affecting the res- piration. It would appear that stimulation of the respiratory centre in the medulla oblongata depends primarily upon the condition of the blood. If the blood is very rich in oxygen, the respirations are feeble and shallow; if, on the other hand, the blood is highly venous, the respirations are deeper and more frequent, a con- dition known as hyperpnoea. If the blood remain venous, the respirations gradually become forced and laboured until we get the condition called dyspnoea. Should the blood get more and more venous, the impulses generated in the respira- tory centre become more and more vehement, and the condition of asphyxia is seen. These nervous impulses, instead of con- fining themselves to the usual nerves distributed to the ordinary respiratory muscles, overflow on to other nerves and put into action other muscles, until there is scarcely a muscle in the body 1 See Preliminary Chapter. Chap. XIII] RESPIRATION 233 that is not affected. The muscles which are thus more and more thrown into action are especially those tending to cany out or to assist expiration, and at last, if no relief is afforded, the violent respiratory movements give way to general convulsions of the whole body. By the violence of these convulsions the whole nervous system becomes exhausted, the convulsions soon cease, and death is ushered in with a few infrequent and long-drawn breaths. Apnoea means absence of breathing. It may be of two kinds, viz.: - (1) Physiological apnoea, where the blood is so rich in oxygen and poor in carbon dioxide that a respiratory act is unnecessary. (2) Pathological apnoea, which is absence of breathing due to exhaustion of the respiratory apparatus or death. It has been surmised that the excitability of the respiratory nerve-centre is due to certain chemical substances which act as stimulants. When the blood is rich in oxygen, this substance is oxidized or burned, and removed so fast that it is able to exert but little influence on the respiratory nerve-centre; when, how- ever, the blood is poor in oxygen, this substance accumulates, and the nerve-centre is powerfully stimulated. Thus when the blood needs oxygen, the respirations are increased to get, if possible, more air into the lungs; if the blood is too rich in oxygen, the respirations become abnormally quiet and shallow. MODIFIED RESPIRATORY MOVEMENTS Various emotions may be expressed by means of the respira- tory apparatus. Sighing is a deep and long-drawn inspiration, followed by a sudden expiration. Yawning is an inspiration, deeper and longer continued than a sigh, drawn through the widely open mouth, and accompanied by a peculiar depression of the lower jaw. Hiccough is caused by a sudden inspiratory contraction of the diaphragm; the glottis suddenly closes and cuts off the column of air just entering, which, striking upon the closed glottis, gives rise to the characteristic sound. Sobbing is a series of convulsive inspirations during which the glottis is closed, so that little or no air enters the chest. 234 ANATOMY FOR NURSES [Chap. XIII Coughing consists, in the first place, of a deep and long-drawn inspiration by which the lungs are well filled with air. This is followed by a complete closure of the glottis, and then comes a forcible and sudden expiration, in the midst of which the glottis suddenly opens, and thus a blast of air is driven through the upper respiratory passages. Sneezing consists of a deep inspiration, followed by a sudden and forced expiration, which directs the air through the nasal passages. Laughing consists essentially in an inspiration, followed by a whole series of short, spasmodic expirations, the glottis being freely open during the whole time, and the vocal folds being thrown into characteristic vibrations. Crying consists of the same respiratory movements as laugh- ing; the rhythm and the accompanying facial expressions are, however, different, though laughing and crying often become indistinguishable. Speaking consists of a voluntary expiration and the vibration of the vocal folds as the air passes over them. SUMMARY Respiratory Apparatus 1. Larynx. 2. Trachea. 3. Bronchi. 4. Lungs. Triangular box made up of nine pieces of cartilage. Situated between the tongue and trachea. Contains vocal folds. Slit or opening between folds called glottis, which is pro- tected by leaf-shaped lid called epiglottis. Larynx. Connected with external air by Mouth. Nose. Fibrous and muscular tube, 4| in. long. Strengthened by C-shaped hoops of cartilage Complete in front. Incomplete behind. Trachea Extends from larynx to third thoracic vertebra, where it di- vides into two bronchi. Bronchi Right and left - structure similar to trachea. Divide into innumerable bronchial tubes or bronchioles. Right - three lobes Larger, heavier, broader, shorter Smaller, narrower, longer Lungs . Cavity of thorax. Left - two lobes Chap. XIII] RESPIRATION 235 f Closed sac. Envelops lungs, but they are not in it. Pleura. . , Two layers Visceral - next to lung. Parietal - outside of visceral Moistened by serum. Hollow, spongy organs. Consist of bronchial tubes - infun- dibula- alveoli, also blood-vessels, lymphatics, and nerves held together by connective tissues. Anatomy of Lungs Blood for aeration. Accompany bronchial tubes. Plexus of capillaries around alveoli. _Returned by pulmonary veins. Blood-vessels „ , , Pulmonary artery Bronchial arteries - supply lung substance. Chest cavity enlarged Elevation of ribs. Descent of diaphragm. Inspiration Respiration Lungs expand. Air rushes in through trachea and bronchi. Chest cavity made smaller Inspiratory muscles relax. Recoil of elastic thorax. Recoil of elastic lungs. Expiration Air forced out through trachea. 'Age. Activity. . Rest - sleep. Respiratory Rate 18 times per minute. Influenced by Ratio to pulse 1 to 4. Involuntary act. Nervous impulses arise in medulla oblongata. A little more than 1 gallon of air (4500 c.c.) ' Residual Capacity of Lungs | Tidal I Reserve Complementary Vital capacity, 3700 c.c. Effect of Respiration upon the Air outside the Body ' Loses- oxygen, 4 to 5 per cent. Carbon dioxide, 4 to 5 per cent. Waste matter. Temperature - expired air is as hot as blood. Moisture - expired air is saturated with moisture Gains r Gains - oxygen [ Oxyhaemoglobin. [ Scarlet colour. Effect of Respiration upon the Blood In lungs Loses [ Carbon dioxide. | Water and waste matters. Loses -- Oxygen f Oxidation. [ Crimson colour. In tissues Carbon dioxide. Water and waste matters. Gains Respiration and Circulation I Intimately connected. Arterial blood - respirations - feeble and shallow. l Venous blood - respirations-deeper and more frequent. CHAPTER XIV THE DIGESTIVE APPARATUS: ALIMENTARY CANAL AND ACCES- SORY ORGANS THE DIGESTIVE APPARATUS The digestive apparatus consists of the alimentary canal and the accessory organs; (1) the salivary glands, (2) the tongue, (3) the teeth, (4) the pancreas, and (5) the liver. ALIMENTARY CANAL The alimentary canal is a musculo-membranous tube extending from the mouth to the anus. It is between twenty-seven and twenty-eight feet long, and the greater part of it is coiled up in the cavity of the abdomen. The diameter of the tube is by no means uniform, being considerably dilated in certain parts of its course. It is composed of three coats, the serous coat being absent from the mouth, to where it passes through the dia- phragm, and of four coats in the abdominal cavity. These coats are: - (1) The mucous (2) The areolar, or sub-mucous Both described in Chapter VII. (3) The muscular coat is composed for the most part of un- striped muscular fibres, the layers of which are disposed in various ways, the most general arrangement being in a lon- gitudinal and circular direction. By the alternate contraction and relaxation of fibres arranged in this fashion (the contractions starting from above), the contents of the tube are propelled from above downwards. 236 Chap. XIV] THE DIGESTIVE APPARATUS 237 (4) The serous coat is derived from the peritoneum, which is the serous membrane lining the walls and covering the viscera of the abdomen. Into the interior of the alimentary canal are poured secre- tions from the glands in the mucous membrane with which it is lined, and also secretions from the accessory glands, which lie outside the canal and are connected with its interior by ducts. In the larger part of its course it contains more or less gas. This serves to keep the opposite walls somewhat separated from each other and prevents the injury which might result from the rubbing together of these soft and delicate structures. In some regions, however, as in the gullet, the opposite surfaces are in contact nearly all the time, but here the structure of the mucous membrane is different from that in the stomach and intestines. The alimentary canal, for convenience of description, may be divided into: - Mouth, containing tongue and teeth. Pharynx. (Esophagus. Stomach. Small or thin intestine ' Duodenum. Jejunum or empty Ileum or twisted. Large or thick intestine ' Caecum. Colon. L Rectum. For convenience of description, the abdomen may be artificially divided into nine regions by drawing the following arbitrary lines: - 1. Draw a circular line around the body at the level of the tenth costal cartilages. 2. Draw another circular line at the level of the anterior superior spines of the ilia. 3. Draw a vertical line upward from the centre of the in- guinal ligament (Poupart's ligament) on right side of body. 4. Draw a similar line on left side of body. The viscera contained in these different regions are as follows:- 238 ANATOMY FOR NURSES [Chap. XIV RIGHT HYPOCHON- DRIAC REGION EPIGASTRIC X REGION LEFT HYPOCHON- DRIAC REGION ^CARTILAGE OF TENTH RIB RIGHT LUMBAR REGION UMBILICAL • © REGION LEFT LUMBAR REGION ^HIGHEST LEVEL I OF ILIAC CREST RIGHT < ILIAC | \regionJ LEFT ILIAC REGION/ ANT. SUP. ILIAC SPINE HYPOGASTRIC REGION Fig. 154. - Regions of the Abdomen. (Gerrish.) Right Hypochondriac. - The right lobe of the liver and the gall-bladder, he- patic flexure (right colic flexure) of the colon, and part of the right kidney. Right Lumbar. - As- cending colon, part of the right kidney, and some convolutions of the small intestines. Right Inguinal (Iliac). - The caecum, appendix caeci. Epigastric Region. - The middle and pyloric end of the stomach, left lobe of the liver, the pan- creas, the duodenum, parts of the kidneys and the supra-renal capsules. Umbilical Region. - The transverse colon, part of the great omentum and mesentery, transverse part of the duodenum, and some convolutions of the jeju- num and ileum, and part of both kidneys. Hypogastric Region. - Convolutions of the small intestines, the blad- der in children, and in adults if distended, and the uterus during preg- nancy. Left Hypochondriac. - The cardiac end of the stomach, the spleen and extremity of the pancreas, the splenic flexure (left colic flexure) of the colon, and part of the left kidney. Left Lumbar. - De- scending colon, part of the omentum, part of the left kidney, and some con- volutions of the small in- intestines. Left Inguinal (Iliac) . - Sigmoid flexure of the colon. Chap. XIV] THE DIGESTIVE APPARATUS 239 MOUTH, OR BUCCAL CAVITY The mouth is a nearly oval-shaped cavity with a fixed roof anteriorly, a flexible roof posteriorly, and a movable floor. It is bounded in front by the lips, on the sides by the cheeks, below by the tongue, and above by the palate. The palate. - The palate consists of a hard portion in front formed by bone, covered by mucous membrane, and of a soft Fig. 155.-Sagittal Section of the Face and Neck, showing the First Portions of the Alimentary and Respiratory Tracts. (Gerrish.) portion behind containing no bone. The hard palate forms the partition between the mouth and nose; the soft palate arches backwards and hangs like a curtain between the mouth and the pharynx. Hanging from the middle of its lower border is a pointed portion of the soft palate called the uvula (little grape). 240 ANATOMY FOR NURSES [Chap. XIV Palatine arches. - From the base of the uvula on either side there passes a curved fold of muscular tissue covered by mucous membrane, which shortly after leaving the uvula is, as it were, split into two pillars, the one going outward, downward, and forward, passing to the side of the tongue, the other outward, downward, and backward to the side of the pharynx. These pillars are known respectively as the anterior pillars of the fauces (glos- sopalatine) and the poste- rior pillars of the fauces (pharyngopalatine). Tonsils. - In the lower part of the triangular space between the anterior and posterior pillars on either side lie the small masses of lymphoid tissue called ton- sils. (See page 211, Chapter XII.) The palate, uvula, pala- tine arches, and tonsils are plainly seen if the mouth is widely opened and the tongue depressed. The fauces is the name given to the aperture leading from the mouth into the pharynx, or throat cavity. The salivary glands. - The mucous membrane lining the mouth contains many minute glands which pour their secretion upon its surface, but the chief secretion of the mouth is supplied by the salivary glands, which are three pairs of compound sac- cular glands called the parotid, submaxillary, and sublingual, respectively. Each parotid gland is placed just under and in front of the ear; its duct passes forward along the cheek, until it opens into the interior of the mouth opposite the second upper molar. The submaxillary and sublingual glands are situ- ated below the jaw and under the tongue, the submaxillary Fig. 156. - The Soft Palate and Tonsillar Regions. (Gerrish.) Chap. XIV] THE DIGESTIVE APPARATUS 241 being placed further back than the sublin- gual. Their ducts open in the floor of the mouth beneath the tongue. The se- cretion of these sali- vary glands, mixed with that of the small glands of the mouth, is called saliva. The tongue. - The tongue is a freely mov- able muscular organ attached by its base to the hyoid bone. Be- sides being the special seat of the sense of taste, it is a useful aid in mastication and deglutition.1 The teeth. - The semicircular borders of the upper and lower jaw-bones (the alveolar processes) contain sockets for the recep- tion of the teeth; extending over the bones and a little way into each socket is a dense insensitive fibrous tissue covered by smooth mucous membrane - the gums. There are two sets of teeth developed during life: the first, deciduous, or temporary, and the second, permanent. Deciduous teeth.-In the first set are twenty teeth, ten in each jaw. The cutting of the deciduous teeth begins usually at seven months and ends at about the age of two and one- half years.2 Permanent teeth. - In the second set are thirty-two permanent teeth, sixteen in each jaw. During childhood the deciduous teeth are replaced by the permanent. The first molar usually appears at six years of age. Fig. 157.-The Salivary Glands. 1 A detailed description of the tongue will be found in the chapter on the organs of special sense. 2 The deciduous teeth are usually cut in the following order, the teeth of each group appearing first in the lower jaw: central incisors, 7th month; lateral incisors, 7th to 10th month: front molars, 12th to 14th month; canine, 14th to 20th month; back molars, 18th to 30th month. 242 ANATOMY FOR NURSES [Chap. XIV According to their shape and use the teeth are divided into incisors, canines, premolars, and molars. Right Middle Left Molar Premolar Canine Incisor / Canine Premolar Molar Upper . . . 3 2 1 4 1 2 3 Lower . . . 3 2 1 4 1 2 3 (Collins.) Incisors are eight in number and form the four front teeth of each jaw. They have wide, sharp edges, and are specially adapted for cutting food. PULP-CAVITY. Fig. 158. - Section of Human Molar Tooth. Magnified. (Collins.) Canines are four in number, two in each jaw. The upper canines are commonly called eye-teeth, the lower, stomach teeth. They have a sharp pointed edge, are longer than the incisors, and are specially useful for tearing food asunder, or, as in dogs and other carnivora, for holding prey. Premolars (or bicuspids) are eight in number, four in each jaw. They are broader, with two points or cusps on each crown; these teeth have only one root, the root, however, being more or less completely divided into two. Their function is to cut and grind food. Chap. XIV] THE DIGESTIVE APPARATUS 243 Molars are twelve in number, three on each side above and below. The molars, or true grinders, have broad crowns with small pointed projections, which make them well fitted for crush- ing and bruising the food: they each have two or three roots. The twelve molars do not replace the deciduous teeth, but are gradually added with the growth of the jaws; the last or hin- dermost molars may not appear until twenty-one years of age: hence called "late teeth" or "wisdom teeth." Each tooth consists of three portions: (1) the crown, (2) the root, and (3) the neck. The crown projects into the cavity of the mouth; the root is embedded in the socket. The neck is the slightly constricted part enveloped by the gum. Each tooth is composed principally of dentine, which gives it shape and encloses a cavity, the pulp cavity, which is filled with a highly vascular and nervous tissue called the dental pulp. The dentine of the crown is capped with a dense layer of enamel. The den- tine of the root is covered by cement. These three substances, enamel, dentine, and cement, are all harder than bone, enamel being the hardest substance found in the body. The teeth are developed from epithelium in much the same way as the hairs; for description of which see page 292, Chapter XVII. THE PHARYNX The pharynx, or throat cavity, is a musculo-membranous bag, shaped somewhat like a funnel, with its broad end turned upwards, and its constricted end downwards to end in the oesophagus. It is about four and a half inches (113 mm.) long, and lies behind the nose, mouth, and larynx. Above, it is attached to the base of the skull, and behind, with the cervical vertebrae; in front and on each side are apertures which communicate with the nose, ears, mouth, and larynx. Of these apertures there are seven: - Two in front above, leading into the back of the nose, the posterior nares. Two, one on either side above, leading into the Eustachian tubes, which communicate with the ears. One midway in front, the fauces. Two below, one opening into the larynx and the other into the eesophagus. 244 ANATOMY FOR NURSES [Chap. XIV The mucous membrane lining the pharynx is well supplied with glands, and at the back of the cavity there is a considerable mass of lymphoid tissue. The muscular tissue in the walls of the pharynx is of the striped variety, and when the act of swallow- ing is about to be performed, the muscles draw the pharyngeal bag upwards and dilate it to receive the food; they then relax, the bag sinks, and the other muscles contracting upon the food, it is pressed downwards and onwards into the oesophagus. THE (ESOPHAGUS, OR GULLET The oesophagus is a comparatively straight tube, about nine inches (225 mm.) long, extending from the pharynx, behind the trachea, and through the diaphragm, to its termination in the upper, or cardiac, end of the stomach. The muscular fibres in the walls of the oesophagus are arranged in an external longitudinal and in an internal circular layer. The mucous membrane is disposed in longitudinal folds which disappear upon distention of the tube. The mucous membrane in the mouth, pharynx, and oesophagus is covered for the most part by stratified epithelium. THE STOMACH After the oesophagus perforates the diaphragm it ends in the stomach (gaster), which is the most dilated portion of the ali- mentary canal. It is a hollow pouch placed obliquely in the left side of the upper portion of the abdominal cavity? It is curved upon itself, so that below it presents a long, rounded outline, called the greater curvature, and above, a constricted, concave outline, called the lesser curvature. The greater curvature is directed to the left, and the lesser curvature faces mostly to the right. The fundus, or cardiac, end is the greater extremity, which projects several inches to the left of the oesophagus and is in contact with the spleen. The opposite or smaller end is called the pyloric extremity and lies under the liver. The stomach has necessarily two openings: the one leading into the oesophagus is usually termed the cardiac aperture; the other, leading into the small intestihe, the pyloric. The 1 Epigasti'ic and left hypochondriac region. Chap. XIV] THE DIGESTIVE APPARATUS 245 pyloric aperture is guarded by a kind of valve composed of strong sphincter-like, circular bands of muscle, which form a constricted ring projecting into the pyloric opening. By this arrangement, the food is kept in the stomach until it is Fig. 159. - 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. (Gerrish.) ready for intestinal digestion, when the circular fibres relax and allow it to pass. When distended, the stomach measures about fifteen inches (38 cm.) from end to end and about five inches (13 cm.) antero- posteriorly, and has a capacity of about one quart. The above 246 ANATOMY FOR NURSES [Chap. XIV description applies to the position and form of the stomach when normally filled with food, but the student must bear in mind that when empty, the stomach contracts down so as more nearly to approach a true cylinder, the contraction and' dilatation affecting more the greater curvature than the lesser. When contracted, the stomach is shorter as well as of lesser diameter. Coats of the stomach. - It has four coats: from the out- side, (1) serous, (2) muscular, (3) submucous or areolar, and (4) mucous. The serous coat is formed by a fold of the peritoneum. The fold is slung over the stomach, in much the same way as we sling a towel over a clothesline, and covers it before and behind. The anterior and posterior folds unite at the lower border of the stomach and form an apron-like appendage, the omentum, which covers the whole of the intestines. The omentum often con- tains a large amount of fat. The muscular coat of the stomach consists of three layers of unstriped muscular tissue: an outer, formed of longitudinal fibres; a middle, of circular; and an inner, of less well-developed, obliquely disposed fibres. The alternate contraction and relaxation of these fibres cause the food to be carried round and round within the stomach, and at the same time subjects it to considerable pressure. The submucous, also called the areolar coat, is loose and vascular. It carries the nerves and vessels which go to and from the muscular and mucous coats. The mucous coat is very soft and thick, the thickness being mainly due to the fact that it is densely packed with small tubular glands. It is covered with columnar epithelium, and in its undistended condition is thrown into folds or rugae. The surface is honeycombed by tiny, shallow pits, into which the ducts or mouths of the tubular glands open. The glands are of two kinds: (1) peptic, (2) pyloric. During digestion they secrete the gastric juice. Nerves and blood-vessels. - The stomach is supplied with nerves from the sympathetic system, and also with branches from the pneumogastric nerve, which comes from the cerebro- spinal system. The blood-vessels* are derived from the three divisions of the coeliac axis. Chap. XIV] THE DIGESTIVE APPARATUS 247 The small intestine extends from the stomach (pyloric valve) above to the large intestine (valve of the colon) below. It is a convoluted tube about twenty feet (6.0 m.) in length, and fills the greater part of the front abdominal cavity. Its diam- eter at the beginning is about two inches (5 cm.), but it gradually diminishes in size and is hardly an inch (2.5 cm.) in diameter at its lower end. The small intestine is divided by anatomists into three portions: - The duodenum. The jejunum. The ileum. The duodenum. - The duodenum is twelve fingers' breadth in length (eight inches or 20 cm.), and is the widest part of the small intestine. It extends from the pyloric end of the stomach to the jejunum. Beginning at the pylorus, the duodenum at first passes in a direction upward; it then makes a complete bend and passes in a direction downward; it again turns in a right angle direction to the left and passes horizontally across the front of the ver- tebral column. This third portion of the duodenum lies retro- peritoneally, so that only its anterior aspect is covered by peri- toneum. The small intestine now passes forward so as to leave the posterior abdominal wall, and becomes completely invested by peritoneum and has a true mesentery. The point at which it becomes completely invested by peritoneum marks the ter- mination of the duodenum and the beginning of the jejunum. Ths jejunum. - The jejunum, or empty intestine (so called because it is always found empty after death), constitutes about two-fifths of the remainder, or seven and a half feet (2.2 m.) of the small intestine, and extends from the duodenum to the ileum. The ileum. - The ileum, or twisted intestine, constitutes the balance of the small intestine, and extends from the jejunum to the large intestine, which it joins at a right angle. There is no definite landmark to determine the point at which the jejunum ceases and the ileum begins, although the mucous membrane of the one differs somewhat from the mucous mem- THE SMALL OR THIN INTESTINE 248 ANATOMY FOR NURSES [Chap. XIV brane of the other; the change is a gradual transition, and one structure shades off into the other. The lengths in feet as given are arbitrary, but those usually accepted. Coats of the small intes- tine. - The small intestine has four coats, which corre- spond in character and arrangement with those of the stomach. The serous coat furnished by the peritoneum forms an almost complete covering for the whole tube except for part of the duodenum. In this situation, the double fold of the peritoneum passing from the posterior abdominal wall to the intestine is called the mesentery, and between its two layers are numerous blood-vessels, lymphatics, and lymph nodes. The muscular coat of the small intestine has only two layers: an outer, thinner, and longitudinal; and an inner, thicker, and circular. The submucous, or areolar coat, carries blood-vessels, lymphatics, and nerves. The mucous coat is highly developed. In the first place, it is largely increased by being arranged in circular folds (valvulse conniventes) which project transversely into the interior of the tube. The onward course of the food is delayed by being caught in the hollows formed by these folds, and thus more thoroughly subjected to the action of the digestive juices: this arrangement also affords a larger surface for absorption. The circular folds are not found in the beginning of the duodenum, but begin to appear one (25 mm.) or two inches (50 mm.) from the pylorus; about the middle of the jejunum they begin to decrease in size, and in the lower part of the ileum they almost entirely disappear. Fig. 160. - Portion of Small Intes- tine LAID OPEN TO SHOW CIRCULAR FOLDS. (Collins.) Fig. 161. - An Intes- tinal Villus, a, a, a, columnar epithelium ; b, b, capillary network ; d, lacteal vessel. Chap. XIV] THE DIGESTIVE APPARATUS 249 Secondly, the surface of the mucous membrane is increased by the minute finger-like projections which are so close set as to give a velvety appearance to the membrane. These pro- jections, or villi, as they are termed, extend throughout the whole length of the small intestine, and are especially provided for purposes of absorption.1 Each villus is a portion of the Fig. 162. - Portion of the Mucous Membrane, from the Ileum. Moderately magnified, exhibiting the villi on its free surface, and between them the orifices of the tubular glands. 1, portion of an aggregated lymph nodule; 2, a solitary lymph nodule; 3, fibrous tissue. (Collins.) mucous membrane, and consists of an external layer of columnar cells attached to a basement membrane, and a central network of blood capillaries surrounding a minute lymph channel called a lacteal. The blood-vessels and lymphatics of the villi communi- cate with networks of both vessels in the submucous coat below. Besides these projections formed for absorption, the mucous membrane is thickly studded with secretory glands. Glands and nodes of the small intestine. - They are of three types: (1) intestinal glands, (2) duodenal glands, (3) lymph nodules. (1) Intestinal glands.2 - These glands are found all over the surface of the small and large intestine. They are simply tubular depressions in the mucous membrane, lined with co- lumnar epithelium. (2) Duodenal glands. - These glands are better known as Brunner's glands. They are compound glands found in the submucous tissue of the duodenum. The intestinal and duo- denal glands secrete the intestinal juice. (3) Lymph nodules. - These are of two varieties, (a) solitary lymph nodules, (b) aggregated lymph nodules of Peyer. (See page 210, Chapter XII.) 1 Their number is estimated at from four to ten millions. 2 More frequently called "follicles," or crypts of Lieberkuhn. 250 ANATOMY FOR NURSES [Chap. XIV The lymph nodules may be regarded as the picket line of the great army of lymph nodes found in the mesentery. THE LARGE OR THICK INTESTINE The large intestine is about five feet (1.5 m.) long, and from two and a half, to one and a half inches (63 to 38 mm.) wide: it extends from the ileum to the anus. Like the small intestine, it is divided into three parts: the ceecum (with the vermiform appendix), colon, and rectum. The caecum. - The csecum (coccus, blind) is a large blind pouch at the commencement of the large intestine. The small intestine opens into the side wall of the large intestine about two and a half inches (63 mm.) above its - the large intestine's - commencement, the caecum forming a cul-de- sac below the opening. At- tached to the lower end of the caecum is a narrow, worm-like tube about the size of a lead- pencil, the vermiform appen- dix. The caecum and appendix lie just beneath the abdominal wall in the right iliac region. Valve of the colon (ileo- caecal). - The opening from the ileum into the large intes- tine is provided with two large projecting lips of mucous membrane which allow the passage of material into the large intestine, but effectually prevent the passage of material in the opposite direction. These mucous folds form what is known as the valve of the colon. The colon. - The colon may be subdivided into the ascending, transverse, and descending colon, with the sigmoid flexure. The ascending portion runs up on the right side of the abdomen until it reaches the liver, then bends abruptly to the left (right colic or hepatic flexure), and is continued across the abdomen as the transverse colon until, reaching the left side (left colic or splenic Fig. 163. - Cavity of the Caecum, its Front Wall having been cutaway. The valve of the colon and the opening of the appendix are shown. (Gerrish.) Chap. XIV] THE DIGESTIVE APPARATUS 251 flexure), it turns abruptly and passes downwards as the descend- ing colon. Reaching the left iliac region on a level with the margin of the crest of the ilium, it makes a curve like the letter S, - hence its name of sigmoid flexure, - and finally ends in the rectum. The rectum. - The rectum is from six to eight inches (15 to 20 cm.) long; it passes obliquely from the left until it reaches the middle of the sacrum, then it follows the curve of the sacrum and the coccyx,, and finally arches slightly backwards to its ter- mination at the anus. The anal opening is guarded by two circular muscles called, respectively, the internal and external sphincters. Coats of the large intestine. - The large intestine has the usual four coats, except near its termination, where the serous is wanting. The muscular coat, along the caecum and colon, has a peculiar arrangement. The longitudinal fibres are gath- ered up in three thick bands, and these bands, being shorter than the rest of the tube, the walls are puckered between them. The mucous coat possesses no villi and no circular folds. It contains numerous tubular glands and solitary lymph nodules which closely resemble those of the small intestine. Peristalsis. - This term is used to describe the alternate contractions and dilatations of adjoining segments of the in- testine. It produces a wave-like motion (worm-like) along the intestinal tract away from the stomach. The action of the oesophagus and stomach is also described as peristaltic. ACCESSORY ORGANS OF DIGESTION The accessory organs of digestion are (1) the salivary glands, (2) the tongue, and (3) the teeth (which have already been sufficiently described), (4) the pancreas, and (5) the liver. PANCREAS The pancreas is an elongated organ, of a pinkish colour, which lies in front of the first and second lumbar vertebrae and behind the stomach. It weighs between two and three ounces (60 to 90 grammes) is about six inches (150 mm.) long, two inches (50 mm.) wide, and one-half inch (12.5 mm.) thick. In shape it 252 ANATOMY FOR NURSES [Chap. XIV somewhat resembles a hammer, and is divided into head, body, and tail. The right end or head is thicker and fills the curve of the duodenum, to which it it firmly attached. The left, free end is the tail, and reaches to the spleen. The intervening portion is the body. Structure of the pancreas. - It is a compound secreting gland, and so closely resembles the parotid gland that it is sometimes called the "abdominal salivary gland." It consists of minute - - CYSTIC DUCT W COMMON BILE pUCT - ORIFICE OF ACCESSORY - PANCREATIC DUCT ORIFICE. OF BILE AND PANCREATI.C DUCTS SUP. MESENTERIC ARTERY Fig. 164. - Ducts of the Pancreas. Part of the front wall of the duodenum is cut away. (Gerrish.) tubes coiled up into little masses called lobules, each lobule having its own duct. The lobules are joined together by con- nective tissue to form lobes, and the lobes, united in the same manner, form the gland. The small ducts open into one main duct about the size of a goose-quill, which runs lengthwise through the gland, from the tail to the head. The pancreatic and common bile duct enter by means of a common opening into the duo- denum about two (50 mm.) or three inches (75 mm.) beyond the pylorus. The secretion formed in the pancreas and dis- Chap. XIV] THE DIGESTIVE APPARATUS 253 charged by the pancreatic duct is called the pancreatic juice. Scattered throughout the pancreas are round or ovoid bodies known as the islands of Langerhans. Each island is about one twenty-fifth inch (1 mm.) in diameter and consists of a group of many-sided cells. They are surrounded by a rich capillary network. Considerable evidence supports the theory that the internal secretion of the pancreas is formed by these islands. THE LIVER The liver (hepar) is the largest gland in the body, weighing ordinarily from fifty to sixty ounces (1500 to 1800 grammes). It measures ten to twelve inches (250 to 300 mm.) from side to side, six to seven inches (150 to 175 mm.) from front to back, and three to four inches (75 to 100 mm.) from above RiGHT LOBE LEFT LOBE Fig. 165. - The Liver. Front view. (Gerrish.) downward in its thickest part. It is a dark reddish brown organ, placed in the upper right and middle portion of the abdomen,1 and extending somewhat into the left hypochondriac region. The upper convex surface fits closely into the under surface of the diaphragm. The under concave surface of the 1 Right hypochondriac and epigastric regions. 254 ANATOMY FOR NURSES [Chap. XIV organ fits over the right kidney, the upper portion of the ascend- ing colon, and the pyloric end of the stomach. The number five prevails in the parts and appendages of the liver. Lobes. - It has five lobes: - 1. Right (largest lobe). 2. Left (smaller and wedge-shaped). 3. Quadrate (square). 4. Caudate (tail-like). 5. Spigelian. Fig. 166.-The Liver. Lower surface. (Gerrish.) Ligaments. - It has five ligaments which help to hold it in place: -■ 1. Suspensory, broad, or falciform. 2. Coronary. 3. Right lateral. 4. Left lateral. 5. Round ligament. The first four are formed by folds of peritoneum, and the fifth, or round ligament, results from the atrophy of the umbilical vein of intra-uterine life. Fissures. - It has five fissures, or furrows, on its surface: - 1. Umbilical fissure 2. Gall-bladder fissure 3. Portal or transverse fissure. > Under surface. Chap. XIV] THE DIGESTIVE APPARATUS 255 4. Ductus venous fissure ' 5. Vena cava. ■ Dorsal surface. The main fissure to remember is the portal, or transverse, which is the gateway for vessels, ducts, and nerves to enter and leave the liver. Fig. 167.- Diagrammatic Representation of two Hepatic Lobules. The left-hand lobule is represented with the intralobular vein cut across; in the right-hand one the section takes the course of the intralobular vein, p, interlobular branches of the portal vein; h, intralobular branches of the hepatic veins; s, sub- lobular vein. The arrows indicate the direction of the course of the blood. The liver-cells are only represented in one part of each lobule. Vessels. - It has five sets of vessels: -■ 1. Branches of portal vein. 2. Branches of hepatic artery. 3. Hepatic veins. 4. Bile ducts. 5. Lymphatics. Functions.-The liver may be compared to a wonderful laboratory, the most wonderful in the body. It has three im- portant functions: - 1. Bile secreting.-The cells of the liver manufacture bile from the blood brought to them by the portal vein. The func- tion of bile is considered in the next chapter. 2. Glycogenic. - The cells of the liver take from the blood brought to them by the portal vein a substance called dextrose, which is derived from the carbohydrates eaten. This is stored in the liver in the form of glycogen until such time as the body 256 ANATOMY FOR NURSES [Chap. XIV needs more dextrose then the food eaten furnishes. When such demand is made, the liver cells reconvert the glycogen into dex- trose and pour it into the circulation.1 3. Higher chemical activities: - (a) Renders some substances suitable for nutrition. (6) Changes certain waste products into urea.2 Urea remains in the circulation until the blood reaches the kidneys, where it is excreted. Minute anatomy of liver. - The liver may be regarded as made up of many minute livers called lobules. Each lobule is an ir- regular body about one-twelfth inch (2 mm.) in diameter, com- posed of a multitude of hepatic cells packed so closely together that only enough room is left between them for the passage of vessels and nerves. Thus each lobule is a mass of hepatic cells, pierced everywhere with a network of blood capillaries. Hepatic cells. - They are about yyo o of an inch in diameter, but because of compression are very irregular in shape. They are epithelial cells composed of protoplasm, with a single clear nucleus, but no cell-wall. The portal vein. - The portal vein, after entering the liver, divides into a vast number of branches which form a network surrounding each lobule, and hence are known as interlobular (between the lobules). From this network minute capillaries enter the lobule, penetrate between each cell and thus surround them, so that each cell is generously supplied with blood con- taining the raw material for the manufacture of bile.3 These capillary branches which enter the lobule and surround the cells are called intralobular (within the lobule). These vessels con- verge toward the centre of the lobule like the spokes of a wheel and empty into a vein (intralobular) which carries the blood away from the lobule. The intralobular veins from a number of lobules empty into a much larger vein upon whose surface a vast number of lobules rest, and therefore the name sublobular (under the lobule) is given to this kind of veins. They empty 1 This is an example of an internal secretion. 2 This is another example of an internal secretion. 3 For purposes of description we will consider bile-making as typical of the functions of the liver. Chap. XIV] THE DIGESTIVE APPARATUS 257 into still larger veins, the hepatic, which converge to a few large trunks and terminate in the inferior vena cava, which is em- bedded in the posterior surface of the gland. Fig. 168. - Lobule of Rabbit's Liver, Vessels and Bile Ducts injected. a, central or intralobular vein; b, b, interlobular veins; c, interlobular bile duct. The bile ducts. -The surfaces of the hepatic cells are grooved, and the grooves on two adjacent cells fit together and form a channel into which the bile is poured as soon as it is formed by the cells. These channels form a network between and around the cells as intricate as the network of blood-vessels. They are called intralobular ducts, and empty into larger ducts called in- terlobular. These unite and form larger and larger ducts until two main ducts, one from the right and one from the left side of the liver, unite in the portal fissure and form the hepatic duct. 258 ANATOMY FOR NURSES [Chap. XIV The hepatic duct runs downwards and to the right for about two inches (50 mm.) and then joins at an acute angle the duct from the gall-bladder, termed the cystic duct. The hepatic and cystic ducts together form the common bile duct (ductus com- munis choledochus), which runs downwards for about three inches (75 mm.) and enters the duodenum at the same opening as the pancreatic duct. Hepatic artery. - We must remember that the blood brought to the liver by the portal vein is venous blood from the stomach, spleen, pancreas, and intestines. It is rich with the products of digestion and intended for the manufacture of bile, etc. It is not intended for purposes of nourishment of the liver itself, hence arterial blood is furnished by the hepatic artery. It enters the liver with the portal vein, divides and subdivides in the same way, thus forming another network between the lobules, and in the lobules between the cells. The capillaries from the portal vein and the hepatic artery are separate and distinct until, near the centre of each lobule, they unite and all the blood supplied to the liver is carried away from it by the one set of veins de- scribed under head of portal vein. Lymphatics. - There is a deep and superficial set. They begin in irregular spaces in the lobules, form networks around lobules, and run always from the centre outward. They drain off waste products and unconsumed nutritious substances. Glisson's capsule. - The whole liver is invested in an outer capsule of areolar connective tissue, which is reflected inward at the portal fissure and encloses the vessels and ducts passing through this opening. Serous membrane. - With the exception of a few small areas, the liver is enclosed in a serous tunic derived from the peritoneum. Nerves are derived from the left pneumogastric and solar plexus. GALL-BLADDER The gall-bladder (vide Fig. 166) is a banana-shaped sac, lodged in a depression on the under surface of the right lobe of the liver. It is lined by mucous membrane, and its walls are formed of fibrous and muscular tissue. It is held in position by the peritoneum, and serves as a reservoir for the bile. During digestion the bile is poured steadily into the intestine; in the intervals it is stored in the gall-bladder. Chap. XIV] THE DIGESTIVE APPARATUS 259 SUMMARY Mouth. Pharynx. (Esophagus, or gullet. Stomach. Alimentary Canal Small or thin intestine 'Duodenum. Jejunum. Ileum. Digestive Apparatus Caecum. Colon. Rectum. Accessory- Organs Large or thick intestine ♦ Salivary glands. Tongue. Teeth. Pancreas. Liver. ' 1. Hard palate. 2. Soft palate - uvula, palatine arches, and tonsils. Above - palate Below - tongue. Front - lips. Sides - cheeks. Contains teeth Mouth or Buccal Cavity ' Enamel. Dentine. . Cement. 1. Deciduous (20) 2. Permanent (32) [ Parotid - just under and in front of ear. Salivary Glands Submaxillary [ Sublingual Below the jaw and under the tongue. ' Funnel-shaped bag between mouth and oesophagus. Pharynx r 1. fauces. 2. posterior nares. 2. Eustachian tubes. 1. larynx. . 1. oesophagus. 7 apertures " Tube - 9 in. long. Extends from pharynx to stomach. (Esophagus, or Gullet ' Inner - mucous - disposed in folds. Middle - submucous. 3 coats Outer - muscular Internal circular fibres. External longitudinal fibres. 260 ANATOMY FOR NURSES [Chap. XIV Hollow pouch. Capacity, 1 qt. Oblique position in epigastric and left hypochondriac regions. Greater and lesser curvature. Fundus or cardiac end and pyloric extremity. Outer - serous - peritoneum. [ 1. Longitudinal fibres. 2. Circular. [ 3. Oblique. Stomach, or Gaster Muscular 4 coats Submucous - vascular. r Rugae. Mucous Glands Peptic Pyloric Gastric juice. Nerves Sympathetic system. Pneumogastric nerve. Blood-vessels from coeliac axis Convoluted tube extends from stomach to valve of colon 20 ft. coiled up in abdominal cavity. 3 divisions Duodenum. Jejunum, or empty. Ileum, or twisted. ' 1. Serous from peritoneum, called mesentery. Small or thin Intestine 2. Muscular ' Longitudinal layer. Circular layer. ' Blood-vessels. Lymphatics. . Nerves. 4 coats 3. Submucous Circular folds. Villi - contain lacteals. 4. Mucous Intestinal glands , ® Duodenal or Brunner s Secrete intestinal juice. Glands and Nodes Solitary Aggregated Picket line of lymph nodes. Lymph nodules Extends from ileum to anus. Length, 5 ft.; width, 21 in. to 1$ in. Puckered up by three thick bands. Caecum, with vermiform appendix. Large or thick Intestine Colon ' Ascending. Transverse. . Descending with sigmoid flexure. 3 divisions Rectum - anus ' Internal sphincter. k External sphincter. Usual four coats except rectum, where serous is wanting. Chap. XIV] THE DIGESTIVE APPARATUS 261 In front of first and second lumbar vertebrae, behind stomach. ' Head attached to duodenum. Body in front of vertebra. Tail reaches to spleen. Pancreas . Hammer shape Compound gland - coiled tubes form lobules. Lobules held together by connective tissue form lobes. Lobes form gland. Duct from each lobule empties into pancreatic duct. Largest gland in body. ' Right hypochondriac. Epigastric. Left hypochondriac. Location Convex above - fits under diaphragm. Concave below -fits over right kidney, ascending colon, and pyloric end of stomach. It has five lobes, five ligaments, five fissures, and five sets of vessels. Glisson's capsule encloses the whole of the liver. Serous membrane from the peritoneum almost completely covers it. Liver . . Hepatic cells in. in diameter grouped in lobules. Lobules in. in diameter. Interlobular veins (between lobules). Intralobular capillaries (within lobules). Intralobular veins (within lobules). Sublobular veins (under lobules). Hepatic vein s - exit at portal fissure, empty into superior vena cava. Branches of portal vein [Channels between cells (within lobules). | Intralobular ducts. i Interlobular ducts. [Hepatic duct - exit at portal fissure. Anatomy of Liver Bile ducts Interlobular arteries (between lobules). Intralobular capillaries (within lobules). Course beyond the intralobular capillaries same as that pursued by blood from portal vein. Branches of hepatic artery ( Start in lobules, form network, and run j from centre to periphery. [ Act as drain-pipes. Lymphatics Banana-shaped sac lodged on under surface of liver. Reservoir for bile. Capacity about 1 oz. Gall-bladder 3 coats 1. Mucous membrane. 2. Fibrous and muscular tissue. 3. Serous membrane from peritoneum. CHAPTER XV DIGESTION: CHANGES THE FOOD UNDERGOES IN THE MOUTH, STOMACH, SMALL AND LARGE INTESTINE; ABSORPTION DIGESTION Digestion is the process by means of which the food we take into our mouths is transformed into a condition of solution or emulsion suitable for absorption into the blood. This trans- formation is rapid or gradual according to the nature of the food-stuffs the digestive solvents are called upon to dissolve. We all know practically, for instance, that it takes much longer to digest a piece of beefsteak than a cup of bouillon, and that when we wish to save the digestive powers as much as possible we place a person upon "liquid diet." Enzymes. - The digestion of the various food-stuffs depends entirely on the action of a class of substances known as enzymes, or ferments. Although the exact composition and method of action of enzymes is not understood, it may be said that an en- zyme is a substance a small amount of which, under certain con- ditions, can by its presence convert certain other substances into still other substances without itself (the enzyme) being easily destroyed or weakened. Thus, a small amount of the particular enzyme, called pepsin, can in an acid solution convert proteids into another class of substances known as peptones, without diminution in the quantity or strength of the pepsin used. The enzymes are the products of living organisms, and are not found in inorganic matter. Remembering that the three solid food-stuffs 1 are proteids, fats, and carbohydrates, we will proceed to describe how each 1 See Preliminary Chapter. 262 Chap. XV] DIGESTION 263 of these is transformed into a soluble condition.1 The process may conveniently be divided as follows: - (1) Changes the food undergoes in the mouth, i.e. masti- cation, insalivation, and deglutition. (2) Changes the food undergoes in the stomach, or stomach digestion. (3) Changes the food undergoes in the small intestine. (4) Changes the food undergoes in the large intestine. CHANGES THE FOOD UNDERGOES IN THE MOUTH Mastication.-When solid food is taken into the mouth, it is cut and ground by the teeth, being pushed between them again and again by the muscular contractions of the cheeks and the movements of the tongue until the whole is thoroughly crushed and ground down. Insalivation. - During this process of mastication the salivary glands are excited to very active secretion, the saliva is poured in large quantities into the mouth, and mixing with the food moistens it and reduces it to a soft, pulpy condition. A certain amount of air caught in the bubbles of the saliva also becomes entangled in the food, and this facilitates the penetration of the gastric juice. Saliva. - Mixed saliva (spittle) as it appears in the mouth is a glairy, frothy, cloudy fluid, the glairiness or ropiness being due to mucus; micro-organisms are also present in it to some extent, and other foreign matters derived from the food. Saliva is mainly water, containing but little solid matter. It has a specific gravity of from 1.004 to 1.008, and an alkaline reaction. It depends for its special action as a digestive solvent upon a ferment it contains called ptyalin. It is secreted most abun- dantly during the mastication of food. The amount secreted during twenty-four hours is estimated to be from one to two quarts.2 The action of saliva upon the food.-The chief function of saliva is to soften and moisten the food and to assist in mastica- tion and deglutition. It has, however, a certain solvent action 1 Water and inorganic salts are absorbed as such by the blood-vessels. 2 See description of salivary glands, page 240, Chapter XIV. 264 ANATOMY FOR NURSES [Chap. XV upon food-stuffs, especially starch. Upon the fats and proteids it has very little effect except to render them softer and better perpared for the action of the other digestive juices. Ptyalin. - By the ptyalin-ferment present in saliva, starch, which is an insoluble substance, is changed into malt sugar or maltose, a highly soluble and absorbable product. This change is best effected at the temperature of the body,1 in a slightly alkaline solution, saliva that is distinctly acid hindering or ar- resting the process. Boiled starch is changed more rapidly and completely than raw, but the food is never retained in the mouth long enough for the saliva to more than begin the transformation of starchy matters.2 After leaving the mouth, further conversion of starch into sugar is arrested by the acid reaction of the gastric juice, and digestion of this class of food-stuffs is practically suspended until they again come in contact with the alkaline secretions in the upper part of the small intestine. Deglutition, or swallowing. -The food thus softened and moist- ened is collected from every part of the mouth by the movements of the tongue, brought together upon its upper surface, and then pressed backwards through the fauces into the pharynx. The elevation of the soft palate prevents the entrance of food into the nasal chambers, while the epiglottis bars its entrance into the air-passages, and it is guided safely and rapidly through the pharynx into the oesophagus. Here it passes beyond the control of the will; it is grasped by the oesophageal muscles and by a continuous and rapid peristaltic action is carried onwards and downwards into the stomach. During the process of mastication, insalivation, and deglutition the food is first reduced to a soft, pulpy condition; secondly, any starch it may contain begins to be changed into sugar; thirdly, it acquires a more or less alkaline reaction. 1 A temperature of 100° F. in the alimentary canal is necessary for diges- tion, hence iced drinks or iced foods that lower this temperature delay diges- tion. 2 The salivary glands do not become active until the subject is from four to six months old; hence the reason for avoiding starchy food for young infants. (Collins.) Chap. XV] DIGESTION 265 CHANGES THE FOOD UNDERGOES IN THE STOMACH, OR STOMACH DIGESTION During the intervals of digestion the stomach is bathed in an alkaline mucus. The entrance of food acts as a stimulant to the whole organ. The blood-vessels dilate, the glands pour out an abundant secretion upon the mucous lining, and the different layers of the muscular coat are excited to a continuous action. Delayed in the stomach by the contraction of the strong, sphinc- ter-like muscles at the cardiac and pyloric openings, the pulpy mass of food is carried round and round, and thoroughly mixed with the gastric juice until it is dissolved into a thick, grayish, soup-like liquid, called chyme. The chyme thus formed is from time to time ejected through the pylorus, and toward the end of digestion is accompanied by morsels of solid, less well-digested matter. This ejection may occur within a few minutes after the entrance of food into the stomach, but does not usually begin until from one to two hours after, and lasts from four to five, at the end of which time the stomach is, after an ordinary meal, completely emptied. Gastric juice. - Gastric juice, secreted by the peptic and pyloric glands in the mucous lining of the stomach, is a thin, colourless, or pale yellow fluid, of an acid reaction. The amount secreted in twenty-four hours has never been accurately measured, but has been estimated to be about fifteen pints. It contains few solids, and is dependent for its specific action upon two enzymes called (1) pepsin and (2) rennin. Pepsin is only properly active in an acid solution, and we therefore find that free hydrochloric acid in the proportion of 0.2 per cent is always present in normal gastric juice. Action of gastric juice upon the food.-The essential prop- erty of gastric juice is the power it has of decomposing proteid matters, and of converting them into a soluble substance called peptone. Hydrochloric acid. - Besides giving an acid medium, which is necessary for the pepsin to carry on its work, the hydrochloric acid has the distinct property of swelling the proteid fibres, thus giving easier access for the pepsin. Pepsin. - The property of converting proteids into peptones 266 ANATOMY FOR NURSES [Chap. XV is dependent upon the enzyme pepsin. Whatever the proteid may be, whether the albumin of eggs, the gluten of flour in bread, the myosin in flesh, the result is the same; pepsin, in conjunc- tion with an acid at the temperature of the body, transforms them into peptones. Peptones readily dissolve in water, and pass with ease through animal membranes. (See Preliminary Chapter, page 9.) Rennin. - So far as is known, this ferment acts only upon the soluble proteid of milk, which is called casein. It converts this substance into a coagulated mass called curd, which is later prepared for absorption by the action of the enzyme pepsin.1 The gastric juice has no action upon starch. Upon fats it has at most a limited action; that is, if adipose tissue be eaten, it will dissolve the envelopes of the fat-cell and set the fat free, but it has no power to emulsify them. From this it is evident that stomach digestion is of a preparatory character, fitting some of the food for further digestion in the intestines. CHANGES THE FOOD UNDERGOES IN THE SMALL INTES- TINE The chyme, on entering the duodenum, after an ordinary meal, is a mixture of various matters. It contains some undigested proteids; some undigested starch; oils from fats eaten; peptones formed in the stomach; salines and sugar; all mixed with a good deal of water and the secretions of the alimentary canal. This acid mixture passing into the duodenum excites reflexly the se- cretory action of the pancreas, and stimulates the bile to flow from the gall-bladder. The glands of. the small intestine also become active, and all these secretions proceed to further change the food-stuffs that have escaped digestion in the stomach. Pancreatic juice. - Healthy pancreatic juice is a clear, some- what viscid fluid, with a very decided alkaline reaction. It is actively secreted by the pancreas during digestion, and flows into the' intestine in conjunction with the bile. The Germans call the pancreas the 11 abdominal salivary gland," though the pancreatic juice has a far more extensive action than the saliva. 1 Excess of acid due to action of bacteria upon milk-sugar will also cause milk to curdle; example, sour milk. Chap. XV] DIGESTION 267 Action of pancreatic juice upon food. - Pancreatic 1 juice is remarkable for the power it has of acting on all the food-stuffs, - proteids, starch, and fats. The important enzymes or ferments found in pancreatic juice are: - (1) Trypsin. - Trypsin, like pepsin, has the power to trans- form proteids into peptones; trypsin, however, requires an alkaline medium to effect this transformation, while pepsin, as we have already seen, requires the medium to be acid. (2) Amylopsin. - Amylopsin, like ptyalin, has the power to change starch into malt sugar, or maltose. (3) Steapsin. - Steapsin is a ferment capable of decomposing fats. This action is twofold: - (a) It emulsifies them. (6) It splits them up into fatty acids and glycerine. (a) If we shake up olive oil with water, the two cannot be got to mix: as soon as the shaking ceases, the oil floats to the top; but if we shake up olive oil with pancreatic juice, the oil remains evenly suspended in it. The reason of this is that the oil has been minutely divided into tiny droplets, and each droplet sur- rounded by a delicate envelope supplied from the albumin in the pancreatic juice, so that they cannot fuse together to form the large drops, which would soon float to the top.2 (6) The fats that are not emulsified are broken up into glyc- erine and fatty acids. The glycerine is absorbed, and the fatty acids in the presence of an alkali form soaps which are soluble in water and capable of absorption. It is probable that the greater part of the fat is absorbed by the latter method. Bile. - Bile, secreted in the lobules of the liver and stored in the gall-bladder until needed, is a fluid of a golden brown or greenish colour, with an alkaline reaction. The quantity se- creted in twenty-four hours varies with the amount of food taken, but is estimated at from forty to sixty ounces. Its composition is approximately:- 1 Pancreatic juice is an external secretion. In addition the groups of cells which constitute the islands of Langerhans are supposed to form an internal secretion, which is instrumental in the normal consumption of sugar. Removal of the entire pancreas is followed by glycosuria. 2 This fine subdivision of fats gives the white colour to the chyle, which is its most striking external characteristic, the innumerable tiny oil drops reflecting all the light that falls on its surface. 268 ANATOMY FOR NURSES [Chap. XV Water 859.2 Solids - bile salts 1 91.5 Fats 9.2 Cholesterin 2.6 Mucus and coloring matter 2 29.8 Salts 7.7 140.8 = 1000.0. Action of bile on food. - Its most important function as a digestive is noted in its action on fats. (1) It splits up neutral fats and, assisted by the pancreatic juice, emulsifies and saponifies them. (2) It aids in the absorption of fats. The passage of digested food through membranes is assisted by wetting the membranes with bile or with a solution of bile salts. It is known that oil will pass to a certain extent through a filter paper, kept wet with a solution of bile-salts, whereas it will not pass, or passes with extreme difficulty, through one kept wet with distilled water. (3) It has a feeble and questioned antiseptic action on food. Outside the body, its presence hinders putrefactive changes; and when it is prevented from flowing into the alimentary canal, the contents of the intestine undergo changes which do not otherwise take place, and which lead to the appearance of vari- ous products, especially of ill-smelling gases. It is also described as a " circulating liquid." It is secreted by the liver and poured into the intestines. All but about one-sixteenth is reabsorbed and returned to the liver by the portal vein. (4) It acts as a mild laxative by stimulating peristalsis.3 Succus entericus, or intestinal juice. - Succus entericus is the secretion of the intestinal glands. It is a clear, yellowish fluid, having a marked alkaline reaction and containing a certain quantity of mucus. Its effect upon digestion is not fully under- stood. Its chief function seems to be to act as a diluent and supply a loss of fluid. Due to this action the contents of the small intestine are about as fluid when they enter the colon as when they leave the stomach. During the passage of the food through the small intestine, 1 Bile salts are (1) sodium glycocholate and (2) sodium taurocholate. 2 Colouring matter, or bile pigments, are (1) biliverdin and (2) bilirubin. 3 Slow peristalsis will cause constipation, and is often associated with a torpid liver. As bile is a natural stimulant to the muscles of the bowel, an insufficient quantity may result in slow peristalsis. Chap. XV] DIGESTION 269 the remaining proteids, starch, and fats are converted into pep- tones, sugar, and emulsified fats or soluble soaps, and these products, as they are formed, pass either into the lymphatics or into the blood-vessels in the intestinal walls, so that the contents of the small intestine, by the time they reach the valve of the colon (ileo-caecal), are largely deprived of their nutritious con- stituents. CHANGES THE FOOD UNDERGOES IN THE LARGE INTESTINE The chyme which enters the large intestine still continues under the influence of the ferments, and the process of digestion continues. The contents are acid, although the secretions of the intestinal walls are alkaline, and certain acid fermentations must therefore take place in them. These are probably due to the action of micro-organisms; but however this may be, the chief work of the colon is absorption. By the abstraction of all the soluble constituents, and espe- cially by the withdrawal of water, the liquid contents become, as they approach the rectum, changed into a firm and solid mass of waste matters, ready for ejection from the body, and called feces. The feces. - The feces consist of the undigested and indiges- tible substances of the food: among them are the elastic fibres of connective tissue; the cellulose, which is the chief constituent of the envelopes encasing the cells of plants; the indigestible mucin of mucus. These three materials, together with some water, some undigested food-stuffs, and some excretory sub- stances found in the various secretions poured into the aliment- ary canal, form the bulk of the material expelled from the body. Defecation. - This term is applied to the act of expelling the feces from the rectum. Note. - For the sake, of simplicity, we have considered digestion in a broad way as the conversion of practically non-diffusible proteids and starch into more diffusible peptones and highly diffusible sugar, and as the emulsifying and splitting up of fats. There is reason to believe that some of the sugar may be changed into lactic acid, or even into butyric or other acids, and that some of the proteids are carried beyond the pep- tone condition. But there is no doubt that the greater part of the proteid is absorbed as peptone, that carbohydrates are mainly absorbed as sugar, and that the greater part of the fat passes into the body as an emulsion. 270 ANATOMY FOR NURSES [Chap. XV ABSORPTION This is the process by means of which the digested food is taken from the intestines and carried into the blood. We have now to consider this process, for, properly speaking, though the food may be digested and ready for nutritive purposes, it is, until it passes through the walls of the alimentary canal, still practically outside the body. Paths of absorption. - There are two paths by means of which the products of digestion find their way into the blood: - (1) By the capillaries in the walls of the stomach and intestines. (2) By the lymphatics in the walls of the small intestine (the lacteals). (1) The network of capillary blood-vessels is spread, as we have seen, immediately beneath the basement membrane of the mucous coat lining the interior of the alimentary canal, and matters in solution pass readily by diffusion or osmosis from the interior of the stomach (to a slight extent only) and intes- tines into the blood-vessels in their walls. In this way proteids, carbohydrates, water, and inorganic salts are absorbed. Proteids are first changed by the digestive juices into peptones and in passing through the mucous membrane of the intestines are converted into serum-albumin. (See page 140, Chapter VIII.) Carbohydrates are first converted into maltose. In passing through the mucous membrane of the intestine, maltose is con- verted into dextrose. All the blood from the digestive organs is taken by the portal vein to the liver. During the passage of the blood through the portal capillaries of the liver, the liver-cells not only take from it the material they need to form the bile; they also take from it the greater part of the dextrose, which they convert into glycogen. This glycogen, stored in the liver-cells, is gradually doled out, as it is needed, to the blood. It is not doled out, however, in the form of glycogen, which closely resembles starch, and is, there- fore, insoluble, but in the form of dextrose. Thus the liver is a very complex organ whose cells elaborate bile and glycogen, and by some ferment-body contained within themselves convert the glycogen into dextrose. After circulating through the liver, the blood is returned to the Chap. XV] DIGESTION 271 general circulation by the hepatic veins. The hepatic veins pour their contents into the inferior vena cava, and the blood, enriched with the products of digestion, finally finds its way into the right side of the heart, whence it is taken to the lungs for purification before being sent to all parts of the body. (2) Matters in solution can pass into the blood-vessels, but some other provision is necessary for the absorption of fats. We find, accordingly, in the villi, which so closely cover the inter- nal surface of the small intestine, little rootlets or beginnings of lymphatic vessels, which are set apart for the absorption of the fatty products of digestion. These lymphatic rootlets, or lacteals, as they are generally called, occupy the centre of each villus. The emulsified and saponified fats pass, probably aided by the bile, into the bodies of the columnar cells on the surface of the villi, and from thence find their way into the interior of the villus, and finally into the beginning of the lacteal. The lacteals carry this fatty matter, or chyle, to the larger lymphatics in the mesentery, and these empty their contents into the chyle cistern of the thoracic duct. Hence it passes on to the blood-vascular system, which it joins at the union of the left internal jugular and subclavian veins. Thus the food in solution after passing through the liver, and the emulsified food after passing through the lymphatics, find their way into the right side of the heart. Final destination of food-stuffs. - It is impossible to say definitely what becomes of the different food-principles after they have once entered the current of the blood. In general, it may be said that the carbohydrates are used for the production of force, and that the fats are stored in the body and used as fuel. The proteids do all that can be done by the fats and carbohy- drates, and in addition form the basis of blood, muscles, and all the connective tissues. Still we cannot say that the carbohydrates perform a certain work in the body and nothing else, or that the proteids and fats do. It is, however, generally understood that the proteids, fats, and carbohydrates each do an individual work of their own better than either of the others can do it. They are also neces- sary in due proportion to the nutrition of the body, and work together as well as in their separate functions. 272 ANATOMY FOR NURSES [Chap. XV The body has always a store of material laid by for future use. If this were not the case, a person deprived of food would die immediately, as he does when deprived of oxygen. The great reserve forces of the body are stored in the form of adipose tissue and glycogen. The glycogen is given out during the intervals between meals to supply material for heat and energy; the adi- pose tissue is not so readily available, but may be called upon during prolonged deprivation from food. For a certain time the heat of the body may be maintained and work done on these substances, although no food except water be taken. Digestion - Is the process of changing food into products capable of ab- sorption. It is dependent on the action of enzymes. SUMMARY Enzymes - Are unformed, non-living ferments found in the digestive juices, Proteids. Carbohydrates. F ats. W ater. Inorganic salts. Food-stuffs Changes food undergoes in mouth rMastication (chewing). Insalivation (mixing with saliva). „Deglutition (swallowing). Changes food undergoes in stomach (stomach digestion). Changes food undergoes in small and large intestines (in- testinal digestion). Defecation, oi' expelling waste. Alimentation The transformation of the food we take into our mouths into products capable of absorption is mainly a chemical process. The mechanical subdi- vision, bruising, and crushing of the food, accomplished by the teeth and the muscular contractions of the walls of the aliamentary canal, is merely a process of preparation for the solvent action of the digestive juices. Of these juices there are five, each having a special action. Parotid. Submaxillary. Sublingual. Secreted by salivary glands which open into the mouth Saliva . . One or two quarts in 24 hours - glairy, frothy, cloudy, liquid. Alkaline reaction. Special enzyme - ptyalin. Ptyalin converts starch into maltose. Chap. XV] DIGESTION 273 Secreted by glands of stomach. Peptic. Pyloric. About 15 pints in 24 hours. Pale yellow liquid. Acid reaction due to free hydrochloric acid, which has the property of swelling proteid fibres. Gastric Juice Pepsin - in an acid medium, temperature 100° F., converts proteids into peptones. Rennin - has a special action on milk. Enzymes Secreted by pancreas, discharged into small intestines dur- ing digestion. Viscid fluid, alkaline reaction. Pancreatic Juice 1. Trypsin - in an alkaline medium, temperature, 100° F., transforms proteids into peptones. 2. Amylopsin - changes starch into maltose. Enzymes 3. Steapsin . . Emulsifies fats. Saponifies fats. Secreted by liver, stored in gall-bladder, discharged into small intestine during digestion. Golden brown or greenish liquid with alkaline reaction. About 40 to 60 oz. in 24 hours. Bile. . . T. Splits up neutral fats. 2. Aids in absorption of fats. 3. Antiseptic action on food. 4. Mild laxative. ction Intestinal Juice Secreted by glands found in intestines , 1. Intestinal or Lieberkuhn's I 2. Duodenal or Brunner's. Principal action is as diluent and to supply a loss of fluid. Absorption is the process of taking up digested food-stuffs and carrying them to the blood. 1. Capillaries in the walls of the stomach and intestines. This blood is carried by means of portal vein to liver, from liver by hepatic veins to inferior vena cava, thence to right auricle. 2. Lymphatics in the walls of small intestine (lacteals) absorb digested fats and empty into chyle cistern of thoracic duct, superior vena cava, and right auricle of heart. Paths of Absorption The food in the blood supplies the wants of the body in five different ways: - " 1. It is used to form all the tissues of the body. " 2. It is used to repair the waste of all the tissues. " 3. It is stored in the body for future use. " 4. It is consumed as fuel to maintain the constant temperature which the body must always possess in a state of health. " 5. It produces muscular and nervous energy." (Professor Atwater.) CHAPTER XVI ELIMINATION; DESCRIPTION OF THE ORGANS CONSTITUTING THE URINARY SYSTEM; GENERAL CHARACTERS OF URINE; SECRETION OF URINE In the last three chapters we have seen that the blood is con- stantly supplied by means of the respiratory and digestive mech- anisms, with all the chemical substances it requires to maintain the life, growth, and activity of the body. These substances, entering the current of the blood, are carried to all the tissues, and are incessantly combining with the chemical substances of which these tissues are composed. These combinations are not left to chance; each tissue has a special affinity for the chemical substance in the blood which it requires for its own growth and special form of activity; the secretory cell of the liver picks out substances from which it can manufacture bile and glycogen; the muscle fibre assimilates those that will promote the changes upon which depends the power of contractility. We know that the proteicl compounds contain the most es- sential elements for the formation of all kinds of tissue, and that phosphate of calcium is a necessary ingredient in the hardening of bone, but we are utterly ignorant of how it comes about that each tissue element is enabled to select the particular material it needs and to reject that which is does not require. Metabolism. - Our bodies are masses of changing atoms, some of which, if we may so express it, are on the "up grade," to construct the various tissues, and some are on the "down grade," to form the waste matters which are the final products of the tissues' activity. These changes, which are incessantly going on while life lasts, are described under the general term of " metabolism." 274 Chap. XVI] ELIMINATION 275 Anabolic. - Constructive changes are spoken of as anabolic. Katabolic. - Destructive changes are spoken of as katabolic. Waste products. - The final products of the metabolism of the body are certain waste matters, the result of the trans- formation of food substances in the fluids and tissues of the body by the process of oxidation. These waste matters resulting from oxidation are principally urea, carbon dioxide, salts, and water. THE ELIMINATION OF WASTE PRODUCTS Broadly speaking, then, the waste products are urea, carbon dioxide, salts, and water. These leave the body by one or other of three main channels, the lungs, the skin, and the kidneys. Some part, it is true, leaves the body by the bowels, for, as we have seen, the feces contain, besides undigested portions of food, substances which have been secreted into the bowels and not reabsorbed, and are therefore waste products. A small amount of the bile is thus lost. The waste matters discharged relatively by the lungs, skin, and kidneys may be stated as follows: - By the lungs: The greater part of the carbon dioxide. A considerable quantity of water. A certain amount of effete matter. By the skin: A variable but, on the whole, large quantity of water. A little carbon dioxide. A small quantity of salts. A small quantity of urea. By the kidneys: All, or nearly all, the urea and allied bodies. The greater portion of the salts. A large amount of water. A very small quantity of carbon dioxide. Having studied in a previous chapter the mechanism by means of which the lungs rid the blood of carbon dioxide and water, it now remains for us to consider the mechanism of the urinary system and the skin. In the present chapter we shall devote ourselves to the consideration of the urinary system. 276 ANATOMY FOR NURSES [Chap. XVI THE URINARY SYSTEM The organs of the urinary system are the two kidneys, which form the urine from materials furnished by the blood: - The two ureters, ducts which convey the urine away from the kidneys. The bladder, a reservoir in which the urine is stored. (See Fig. 116.) The urethra, a tube through which the urine passes from, the bladder and is finally voided. (See Fig. 212.) THE KIDNEYS The kidneys (renes) are two compound tubular glands, placed at the back of the abdominal cavity, one on each side of the spinal column and behind the peritoneal cavity. They are bean-shaped, with the concave side, or hilus, turned toward the spine, and the convex side directed outwards. Each kid- ney is about four inches (100 mm.) long, two (50 mm), broad, and one (25 mm.) thick. They extend from the eleventh rib to within about two inches (50 mm.) of the crest of the ilium. The right is a little lower than the left in conse- quence of the large space occu- pied by the liver. The weight of each kidney is about four to six ounces. Capsule and supports.-The kidneys are covered by a thin but rather tough 'envelope of fibrous tissue called the capsule of the kidney, and are usually embedded in a considerable quantity of fat, which, with the assistance of their vessels and the peritoneum, helps to hold them in place. If we cut a Fig. 169. - Vertical Section of the Kidney. (Collins.) Chap. XVI] ELIMINATION 277 kidney in two lengthwise, it is seen that the upper end of the ureter expands into a basin-like cavity, called the pelvis of the kidney. This pelvis is irregularly subdivided into smaller, cup-like cavities, called calyces, which receive the pointed pro- jections of the kidney substance. The substance of the kidney is readily seen by the naked eye to consist of two distinct parts: (1) An outer, lighter, and more solid portion, called the cortex (bark). (2) An inner, darker, striated portion, called the medul- la (marrow), which is not a solid mass, but more or less distinctly divided into about ten pyramidal- shaped sections. The pointed projections, or papillae, of the pyramids are received by the cup- like cavities or calyces of the pelvis. The bulk of the kidney substance, both in the cortex and medulla, is composed of little tubes or tubules,1 closely packed together, having only just so much connective tissue as is sufficient to carry a large supply of blood- vessels and a certain number of lymphatics and nerves. Renal corpuscles.2 - In the cortical portion of the kidneys are found minute tufts of capillaries which are surrounded by a capsule lined with epithelial cells. Here it is that the uriniferous tubules arise.* Uriniferous tubules. - Exam- ined under the microscope, it is seen that the uriniferous tubules begin as little hollow globes, called capsules, in the cortex of Fig. 170. - Diagram of the Course of two Uriniferous Tu- bules. M, capsule, or dilated ex- tremity ; C, convoluted portion of tube; H, loop, consisting of a de- scending and ascending limb; D, collecting tubule. 1 It is estimated that each kidney contains about fifteen miles of tubing. 2 Old term was Malpighian corpuscles. 278 ANATOMY FOR NURSES [Chap. XVI the kidney.1 These capsules are joined to the tubules by a con- stricted neck, and the tubules, after running a very irregular course, open into straight collecting tubes, which pour their contents through their openings in the pointed ends or papillae of the pyra- mids, into the calyces of the kidney. (Vide Fig. 169.) The tubules are composed of basement membrane, lined throughout by epithe- lial cells. The cells vary in the different parts of a tubule, those of the capsule and convoluted or irregular parts being more especially adapted to secretory pur- poses than the straight parts of the tubule. Pyramid.-These collec- ting tubules en masse, to- gether with interstitial tissue, blood-vessels, and lymphatics, make a pyramid. The blood supply of the kidney. - For its size, the kidney is abundantly sup- plied with blood. The renal artery, coming directly from the aorta, divides as it enters the hilus of the kidney into several branches, which pass into the tissue of the organ. Branches from these arteries have two destinations: (1) into the cortex and (2) into the pyramids. (1) When the arteries reach the level of the base of the pyra- mid, the branches divide laterally to form more or less com- Fig. 171.--Vascular Supply of Kid- ney. (Cadiat.) a, part of arterial arch; b, arterial branch passing upwards through the cortex; c, glomerulus; d, efferent vessel; e, meshwork of capillaries; f, straight arterial vessels of pyramids; g, venous arch; h, straight veins of pyramids. 1 The number of capsules is estimated to be about 500,000. Chap. XVI] ELIMINATION 279 plete arches between the cortex and medulla. From the arterial arches, vessels pass upwards through the cortex (interlobular), giving off at intervals tiny arteries, each of which enters the dilated commencement or capsule of a uriniferous tubule. These tiny arteries, entering the capsule, are spoken of as afferent vessels. They push the thin walls of the capsule before them, break up into a knot of capillary vessels, called a glomerulus, and finally issue from the capsule as efferent vessels. These efferent vessels do not immediately join to form veins, but break up into a close meshwork or plexus of capillaries around the tubules, before they unite to form the larger vessels and pour their contents into the veins. These veins terminate in venous arches between the cortex and medulla. It is in this way that the cortex is supplied with blood. (2) The pyramids also receive their blood supply from the arterial arches. The blood passes downwards in straight vessels between the uriniferous tubules, to be returned by more or less straight veins to the venous arches, whence it is con- veyed by large branches into the renal vein, which leaves the kidney at the hilus and pours its contents into the inferior vena cava. The renal artery in passing into the kidney is accompanied by a network of nerves called the renal plexus. They are chiefly vasomotor nerves, and regulate the contraction and relaxation of the renal blood-vessels. Fig. 172.-Plan of the Blood-vessels con- nected with the Tu- bules. (Note that in the text the term " renal cor- puscles" is used instead of the term " Malpighian body " which is found on the illustration.) THE URETERS The ureters are the excretory ducts of the kidneys. They arise as the pelvis (of the kidney) in the middle of the concave side, or hilus, of each kidney, and proceed obliquely downwards and inwards through the lumbar region of the abdomen into the pelvis, to open obliquely by two constricted orifices into the base of the bladder. 280 ANATOMY FOR NURSES [Chap. XVI Each ureter is of the diameter of a goose-quill, and from twelve to eighteen inches (300 to 450 mm.) long. They consist of three coats: - (1) An inner, or mucous, (2) a middle, or muscular, and (3) an outer, or fibrous. (1) The mucous coat is continu- ous above with that of the pelvis of the kidney, and below with that of the bladder. (2) The muscular coat is ar- ranged in two layers, an inner longi- tudinal, and an outer circular. (3) The fibrous coat carries the blood-vessels and nerves with which the tube is supplied. Fig. 173. -- Diagram show- ing Method of Entrance of the Ureter into the Bladder. (Gerrish.) BLADDER The bladder is the reservoir of the urine. It is a hollow, muscular organ situated in the pelvic cavity behind the pubes. It is customary to speak of the widest part as the fundus, and the part where the bladder becomes continuous with the urethra as the neck, or cervix. It has four coats: - ' 1. Mucous, 2. Areolar. 3. Muscular. 4. Serous. 1. The mucous membrane lining the bladder is continuous with that of the ureters and the urethra. When the bladder is empty, the mucous membrane is thrown into irregular rugae. 2. The areolar coat connects the mucous and muscular. It permits freedom of movement such as is essential in an organ subject to change in size and shape. 3. The muscular coat has three layers, an inner longitudinal, middle circular, and outer longitudinal. The circular fibres are collected into a layer of some thickness around the cervix or neck, where the bladder becomes continuous with the urethra. These circular fibres around the neck form a sphincter muscle which is normally in a state of contraction, only relaxing at Chap. XVI] ELIMINATION 281 intervals, when the accumulation of urine within the bladder renders its expulsion necessary. 4. The serous coat is a reflection of the peritoneum, and only partially covers the bladder. The bladder is a freely movable organ, but is held in position by ligaments. During infancy it is conical in shape and projects above the upper border of the pubes into the hypogastric region. In the adult, when quite empty, it is placed deeply in the pelvis; when slightly distended, it has a round form; but when greatly distended, it is ovoid in shape and rises to a considerable height in the abdominal cavity. The bladder may be de- scribed as having five surfaces: - (1) Superior, or abdominal, that side lying in contact with the abdominal viscera. (2) Anterior, or pubic, that portion lying behind the sym- physis pubis. (3) Posterior, or rectal, the part lying, in the male, against the rectum, and in the female against the vagina and neck of the uterus. (4 and 5) The two lateral surfaces which are very narrow when the bladder is empty. The normal capacity of the bladder (without discomfort) is about eight ounces. THE URETHRA The urethra is a narrow, membranous canal, about an inch and a half (38 mifi.) in length in the female. It extends from the meatus urinarius internus in the bladder to the meatus uri- narius externus in the vulva. It is placed beneath the symphy- sis pubis, and is embedded in the anterior wall of the vagina. Its direction is obliquely downwards and forwards, its course being slightly curved, the concavity directed forwards and up- wards. It admits of considerable dilatation, its normal diame- ter, however, being about a quarter of an inch (6.3 mm.) Its external orifice is the narrowest part and is located between the clitoris and the opening of the vagina. (See Fig. 212, Chapter XX.) It is lined by a - (1) Mucous coat, which is continuous, externally, with that of the vulva and, internally, with that of the bladder. 282 ANATOMY FOR NURSES [Chap. XVI (2) The submucous coat is areolar and contains a network, of large veins. (3) The external muscular coat is also continuous with that of the bladder, and is in two layers, an internal longitudinal, and an external circular. GENERAL CHARACTERS OF THE URINE Normal urine may be described as a transparent watery fluid of a pale yellow colour, acid reaction, specific gravity of 1020, and possessing an odour which can only be described as 11 char- acteristic" or "urinous." Each one of these characters is liable to variation within the limits of health as well as in disease. The transparency of urine may be diminished in health by the presence of mucus, derived from the genito-urinary tract? or by the deposit of salts. In disease the urine may become clouded by the presence of pus. The colour of urine depends mainly upon the amount of water it contains; also upon a diminution or increase of colour- ing matters. In the copious urine of hysteria the colour is very light, while in the diminished flow in fevers it is very high. Abnormal colouring matters are derived from food or medicine, or result from some diseased condition. The reaction of urine should always be tested from a collection of urine passed during twenty-four hours, as it is affected by diet and exercise. To test the reaction of urine, litmus paper is used. Acid urine turns blue litmus paper red; alkaline urine turns red litmus paper blue. When the colour of the paper turns purplish, the urine is said to be neutral. The reaction of mixed urine is normally acid. The specific gravity depends upon the amount of solid waste matters present in the urine. In health, it may vary from 1010 to 1030. When the solids are dissolved in a large amount of water, the specific gravity will naturally be lower than when, from a deficiency of water, the urine is more concentrated. It is notably heightened by the presence of sugar in the disease called Diabetes Mellitus. Chap. XVI] ELIMINATION 283 SECRETION OF URINE Urine is secreted from the blood in two ways: - (1) It is partly removed by a process of transudation or filtration. (2) Also by the secretory action of the cells lining the urinif- erous tubules. (1) Into each dilated extremity or hollow capsule which forms the beginning of a uriniferous tubule a small artery (afferent vessel) enters. This artery breaks up into capillaries within the capsule forming a bunch of looped and twisted blood-vessels called a glomerulus. The walls of the capsule being double, the knot of capillary vessels or glomerulus pushes back the inner wall or visceral layer, until the capsule is quite entirely filled, leaving only a small space between it and the outer wall or parietal layer. The blood in the loop of capillaries or glomeru- lus is only separated from the interior of the tubule by the thin walls of the capillaries and the inverted wall of the capsule, which closely covers the glomerulus. The artery which enters the capsule is larger than the issuing (efferent) vessel, and during its passage through the glomerulus, the blood is subjected to considerable pressure. As a result of this, a transudation of the watery constituents of the blood, with some dissolved salts, takes place through the walls of the blood-vessels and the walls of the capsule into the capsular space, then into the tubule. (2) After leaving the capsule, the efferent vessel communicates with other similar vessels, which together form a meshwork or plexus of capillaries closely surrounding the tubules, so that the blood is again brought into close communication with the in- terior of the tubules. The tubules are lined with secreting cells, and these cells appear to have the power of selecting from the blood the more solid waste matters (especially the urea), which fail to filter through the flat cells forming the wall of the capsule. Thus the elimination of urine is a double process, being partially accomplished by transudation, and partially by the selective action of the secreting cells lining the tubules. AMOUNT OF URINE The average quantity of urine secreted in twenty-four hours is fifty-two fluid ounces (1.54 litres). As little as thirty ounces, 284 ANATOMY FOR NURSES [Chap. XVI or as much as eighty-one ounces may be voided within the limits of health. The quantity varies greatly and is dependent on (1) the activity of the skin, (2) the amount of fluid taken into the body. (1) The excretion of water by the kidneys is closely related to that excreted by the skin. When the body is exposed to cold, the blood-vessels in the skin are constricted, and the discharge of water in the form of sweat is checked; at the same time the blood-vessels of the kidneys are dilated, there is a full and rapid stream of blood through the glomeruli, and an increased flow of urine results. On the other hand, when the body is exposed to warmth, the cutaneous vessels are widely dilated, and the skin perspires freely, while the renal vessels being constricted, only a small and slow stream of blood trickles through the glomeruli, and the urine which is secreted is scanty. (2) The effect on secretion is more marked by the amount of fluid absorbed through the alimentary canal; an increased secretion of water always follows an ordinary meal, and when large quantities of water are ingested the amount of urine is correspondingly increased. The action of some drugs and the character and quantity of food consumed also influences to some extent the quantity of urine secreted. Excretion of urine. - The uriniferous tubules commence in a dilated extremity, the capsule, and after a very devious course terminate in the collecting tubules which open on the pointed projections or papillae of the pyramids. The fluid they contain passes into the pelvis of the kidney, whence it is carried along the ureters into the bladder, partly by pressure and gravity, and partly by the peristaltic contractions of the muscular walls of the ureters. In the bladder the urine collects, its return into the ureters being prevented by the oblique entrance of these tubes into the walls of the bladder. Micturition. - This act is normally caused by the accumula- tion of urine within the bladder. The accumulation stimulates the muscular walls to contract, the resistance of the sphincter at the neck of the bladder is overcome, and the urine is ejected through the urethra. Involuntary micturition may occur as a result of spinal injury involving the nerve centres, which send nerves of control to the bladder. It may be due to a want of Chap. XVI] ELIMINATION 285 "tone" in the muscular walls, or it may result from some ab- normal irritation. THE COMPOSITION OF URINE The chief constituents of normal urine are water, urea, uric acid, hippuric acid, colouring matters or pigments, and salts. Of these constituents, urea is by far the most important, for it is the chief solid waste product of the body. Urea. - Urea is the final product of all proteid substances, and consequently a diet rich in proteids will increase the amount of urea in the system. The result of the combustion of proteid material exists in the blood until the blood reaches the liver. Under the action of the liver cells this material (ammonium carbamate) is converted into urea and remains in the circulation until the blood reaches the kidneys. To eliminate urea is the special work of the kidneys, and if for any reason they fail to execute their work, the accumulation of urea in the system leads to termination of life. (Uremia.) Uric acid and hippuric acid. -Uric acid and hippuric acid are other forms in which nitrogen is eliminated. They probably come, like urea, from food disintegration. The amount found in the blood is especially increased in gout. Pigments. - Various pigments are present to give the urine its characteristic colour. Salts. - Of the salts, chloride of sodium occurs in the largest quantity; it sometimes disappears temporarily, from the urine when, in certain inflammatory diseases, it is needed by the blood. Abnormal constituents. - The chief abnormal constituents that are liable to appear in the urine are albumin, giving rise to a condition called albuminuria, and sugar, giving rise to glycosuria. The "casts," which are found in urine in the various forms of Bright's disease, are shed from the tubules in the shape of cylindrical moulds. When the kidneys are dis- abled, it is customary for physicians to lighten their work as far as possible by regulating the diet and stimulating the action of the skin. 286 ANATOMY FOR NURSES [Chap. XVI SUMMARY Metabolism f . , e uals the 1 Anabolic or constructive changes. y ] Katabolic or destructive changes. sum of the I Waste Products Urea. Carbon dioxide. Salts. Water. r Greater part of carbon dioxide. Considerable quantity of water. L A small quantity of effete matter. Lungs ' Large quantity of water. Small quantity of carbon dioxide. Small quantity of salts. Small quantity of urea. Elimination of Waste Products Skin Kidney: Nearly all urea and allied bodies. Greater portion of salts. Large amount of water. Small amount of carbon dioxide. Kidneys (2) - secrete urine. Ureters (2)-ducts which convey urine from kidneys to bladder. Bladder (1) -reservoir for urine. Urethra (1) -tube through -which urine is voided. Urinary System Bean-shaped, tubular glands. Consist of tubules closely packed together with just enough connective tissue to carry blood-vessels, lymphatics, and nerves. Four inches long, two inches broad, one inch thick. Weight, four to six ounces. Placed on either side of spinal column and extend from eleventh rib to within two inches of crest of ilium. Cortex - outer, lighter, more solid portion. Medulla - inner, darker, striated portion. Kidneys . . Pelvis - Upper expanded end of ureter. Calyces - Cup-like cavities of the pelvis that receive papillae of pyramids. Cone-shaped masses (about ten in number) in the medul- lary portion of the kidney. Bases directed toward cortex. Apices directed toward pelvis. Consist of uriniferous tubules, blood-vessels, and lymphatics, held together by connective tissue. Pyramids . Papillae - Apices of the pyramids. Renal Corpuscles Minute tufts of capillaries in the cortical portion of kidneys which are surrounded by inverted capsule of uriniferous tubule. Chap. XVI] ELIMINATION 287 Begin as hollow globes or capsules in the cortex of kidney, and after a very irregular course open into straight collect- ing tubes which pour their contents into calyces of pelvis. Uriniferous Tubules Glomerulus Knot of capillary vessels. ' Renal artery - direct from aorta. Enters hilus of kidney, divides into many branches. Arterial arches 'Lateral branches at the level of the base of the pyramids. 1. Send branches to cortex (cortical). ^2. Send branches to pyramids. 1. Cortical arteries give off branches which enter (afferent) the capsules of uriniferous tubules, break up into knot of capillaries, leave by efferent vessels, form plexus around urinifer- ous tubule, then unite to form veins and empty into venous arches. 2. Arteries from the arterial arches pass down- ward and supply pyramids with blood. It is returned by veins to the venous arches. Blood Supply of Kidneys 'Lateral branches at level of base of pyramids. Receive blood from cortex. Receive blood from pyramids. Venous , arches Veins empty into renal vein, leave kidney at hilus, and empty into inferior vena cava. Excretory ducts. Extend from kidney to bladder. Size of goose-quill. 12-18 in. long. Ureters . Three coats 1. Mucous - lining. (Inner, longitudinal layer. (Outer, circular layer. 2. Muscular 8. Fibrous - carries blood-vessels and nerves. Reservoir of urine. Hollow muscular organ. Situated in pelvic cavity behind the pubes. Fundus - widest part. Cervix - where the bladder becomes continuous with the urethra. 1. Mucous - lining. 2. Areolar - connects mucous and muscular. Bladder . Four coats 3. Muscular Inner layer - longitudinal. Middle layer-circular. Outer layer - longitudinal. 4. Serous - partial covering derived from perito- neum. Freely movable. Held in position by ligaments. Size, shape, and position depend upon age, sex, and whether < bladder is full or empty. 288 ANATOMY FOR NURSES [Chap. XVI r Membranous canal, extends from the bladder to the vulva. 1| in. long and | in. in diameter in female. 1. Mucous - lining. 1. Submucous - supports network of veins. Urethra Three coats 3. Muscular Inner - longitudinal. External - circular. Pale yellow, watery fluid. Reaction - acid. Specific gravity - 1010 to 1030. Odour - urinous. Urine . . 1. Process of transudation or filtration. Water and saline elements are filtered from the blood during the circu- lation through the glomeruli. 2. Secretory action of the cells lining the uriniferous tubules. Urea and other foreign substances are separated from the blood during the circulation through the plexus of capillaries which surrounds the tubules. Secretion of Urine Average 52 oz. in 24 hr. May vary in health from 30 to 81 oz. Amount of Urine ' 1. Amount of fluid taken into the body. 2. Activity of the skin. 3. The action of some drugs. 4. Character and quantity of food consumed. Dependent on Excretion of Urine The fluid secreted by the uriniferous tubules is poured into pelvis of kidney, thence by way of ureters to bladder, and is voided by means of urethra. Water. Urea Result of combustion of proteid material. Formed in liver, eliminated by kidneys. Composition of Urine Uric acid and ( Closely allied to urea. hippuric acid { Result of food disintegration. Colouring matter - manufactured from materials separated from blood. Salts - chloride of sodium in largest quantity. Abnormal Constituents Albumin - albuminuria. Sugar - glycosuria. Casts - Bright's disease. CHAPTER XVII ELIMINATION CONCLUDED: THE SKIN AND ITS APPENDAGES.- BODILY HEAT: PRODUCTION OF HEAT; LOSS OF HEAT; DISTRIBUTION OF HEAT; REGULATION OF HEAT Having described the mechanism by means of which the lungs rid the body of carbon dioxide and water, and of how the kid- neys relieve it of urea, salts, and water, it now remains for us to explain how the skin plays its part in elimination by yielding up water, a certain amount of carbon dioxide, salts, and urea. THE SKIN The skin, or cutaneous membrane is not, like the kidneys, set apart to perform one special function. It is an important excretory organ, but it is also an absorbing organ; it is likewise the principal seat of the sense of touch, and serves, too, as a protective covering for the deeper tissues lying beneath it. It consists of two distinct layers: - (1) Epidermis, scarf skin, or cuticle. (2) Cutis vera, true skin, derma, or corium. Epidermis. - The epidermis is a stratified epithelium, com- posed of a number of layers of cells. The thickness varies in different parts of the body, measuring in some places not more than 2I0 inch (0-104 mm.), and in others as much as ^4 inch (1.104 mm.). It is thickest in the palms of the hands and on the soles of the feet where the skin is most exposed to friction and pressure, but it forms a protective covering over every part of the true skin, upon which it is closely moulded. It is roughly divisible into two layers: - (1) Superficial, or Horny. (2) Germinative, or Malpighian. 289 290 ANATOMY FOR NURSES [Chap. XVII (1) Superficial, or horny, layer consists of three strata of cells: - (a) Stratnum corneum: the cells of this layer are hard, flattened, and lose their nuclei. stratum ' corneum I ' stratum lucidum J stratum ? granulosum germinative or Malpighian > cutis vera Fig. 174. - Vertical Section through the Skin of the Palmar Side of the Finger, showing Two Papilla (One of which contains a Tactile Cor- puscle) and the Deeper Layer of the Epidermis. (Schafer.) (6) Stratum lucidum: these cells have a clear appearance. (c) Stratum granulosum: these cells contain granules which have been thought to form the horny matter in the superficial cells. (2) Germinative, or Malpighian, layer consists of layers of soft protoplasmic cells, which in the-layer next to the stratum granu- losum are polyhedral, but in the deeper layers next to the true skin are columnar in shape. The growth of the epidermis takes place by the multiplication of the cells in the germinative, or Malpighian, layer. As these Chap. XVII] ELIMINATION 291 cells multiply by cell-division, they push upwards towards the surface those previously formed. In their upward progress they undergo a chemical transformation, and the soft proto- plasmic cells become converted into the flat, horny scales which are constantly being rubbed off the surface of the skin. The pig- ment in the skin of the negro as well as that of the nipple in white races is found in the deepest cells of the germinative layer. No blood-vessels pass into the epidermis; it, however, receives fine nerve-fibrils between the cells of the Malpighian layer. Cutis vera, or true skin.- The cutis vera is a highly sensitive and vascular layer of connective tissue. It is described as consisting of: - (1) Superficial, or papillary layer. (2) Deeper, or recticular layer. (1) The surface of the superficial, or papillary, layer is in- creased by protrusions in the form of small conical elevations, called papillae, whence this layer derives its name. They pro- ject up into the epidermis, which is moulded over them, and contain for the most part looped blood-vessels, but they also contain the terminations of nerve-fibres in the shape of little bodies called tactile corpuscles. The papillae seem chiefly to exist for the purpose of giving the skin its sense of touch, being always well developed where the sense of touch is exquisite. The papillae, containing tactile bodies, are specially large and numerous on the palm of the hand and the tips of the fingers, and on the corresponding parts of the foot, while on the face and back they are small and irregu- larly scattered. (2) The reticular layer of the corium is a continuation of the papillary layer, there being no real division between them. It is made up of bundles of white fibrous and elastic tissue, and contains networks of blood-vessels, lymphatics, and nerves. The cutis vera is attached to the parts beneath it by a layer of areolar tissue, here named "subcutaneous," which layer, with very few exceptions, contains fat. The connection in some parts is loose and movable, as on the front of the neck; in others, close and firm, as on the palmar surface of the hand and the sole of the foot. 292 ANATOMY FOR NURSES [Chap. XVII The appendages of the skin are the nails, the hairs with their sebaceous glands, and the sweat-glands. They are all developed as thickenings, or as down-growths, of the Malpighian layer of the epidermis. The nails. - The nails are composed of clear, horny cells of the epidermis, joined together so as to form a solid, continuous plate. Underneath each nail the true skin is modified to form what is called the bed, or matrix, of the nail. This bed is very vascular, and is raised up into numerous papillae. At the hinder part of the bed of the nail the skin forms a deep fold, in which is lodged the root of the nail. The growth of the nail is accomplished by constant multiplication of the soft cells in the Malpighian layer at the root. These cells are transformed into dry, hard scales, which unite into a solid plate, and the nail, constantly receiving additions from below, slides forward over its bed and projects beyond the end of the finger. When a nail is thrown off by suppuration or torn off by violence, a new one will grow in its place provided any of the cells of the Mal- pighian layer are left. The average rate of growth of the nails is about gb- of an inch (0.78 mm.) per week. The hairs. - The hairs are growths of the epidermis, developed in little pits, the hair-follicles, which extend downwards into the deeper part of the true skin, or even into the subcutaneous tissue. The hair grows from the bottom of the little pit or follicle, the part which lies within the fol- licle being known as the root. The sub- stance of the hair is composed of coalesced, horny cells, arranged in different layers, and we usually dis- tinguish three parts in the stem or shaft of hairs: -• LUNULA... MANTLE Fig. 175. -• Thumb-nail (Gerrish.) Fig. 176. - Piece of Human Haik. (Highly magnified.) a, cuticle; b, fibrous substance; c, medulla. Chap. XVII] ELIMINATION 293 (1) Cuticle - an outer layer of delicate, scale-like cells. (2) Fibrous substance - a middle, horny, thick and coloured portion, formed of elongated cells. (3) Medulla - a central pith formed of angular cells. The root of the hair is enlarged at the bottom of the follicle into a bulb or knob. This bulb is composed of soft-growing cells, and fits over a vascular papilla which projects into the bottom of the follicle. The hair grows from the bottom of the follicle by multiplication of the soft cells which cover the papilla, these cells becoming elongated to form the fibres of the fibrous portion, and otherwise modified to form the medulla and cuticle. New hairs are produced indefinitely, so long as the papillae and soft cells remain intact. The follicles containing the hairs are narrow pits formed by the involutions of the true skin and the epidermis. They slant obliquely upwards, so that the hairs they contain lie down on the surface of the body. Connected with each follicle is a small muscle called the arrector muscle. It is composed of bundles of plain muscular tissue which pass from the surface of the true skin, on the side to which the hair slopes, obliquely downwards, to be attached to the bottom of the follicle. When these muscles contract, as they will under the influence of cold or terror, the little hairs are pulled up straight, and stand "on end"; the follicle also is dragged upwards so as to cause a prominence on the surface of the skin, whilst the cutis vera, from which the little muscle arises, is correspondingly depressed; in this way the roughened condition of the skin known as "goose- skin" is produced. Hairs grow on an average at the rate of half an inch (12.5 mm.) per month. They are found all over the body, except on the palms of the hands and the soles of the feet, and on the last phalanges of the fingers and toes. Sebaceous glands. - The sebaceous glands are small, saccular glands, which lie between the hairs and their arrector muscles. They occur everywhere over the skin surface, with the exception of the palms and soles, and most abundantly in the hairy parts. They are lined with epithelium and secrete a fatty, oily sub- stance (sebum), which as a rule they discharge into the hair- follicles, though sometimes they discharge separately on the surface of the skin. Their size is not regulated by the length 294 ANATOMY FOR NURSES [Chap. XVII of the hair. Thus, some of the largest are found on the nostrils and other parts of the face, where they often become enlarged with pent-up secretion. The sebum is a secretion. It lubricates the hairs and renders them glossy; it also exudes, more or less, over the whole surface of the skin, and keeps it soft and flexible. An accumulation of this sebaceous matter upon the skin of the foetus furnishes the thick, cheesy, oily substance called the vernix caseosa. I HORNY [ LAYER 1 MALPIGHIAN J LAYER DUCT OF SEBACEOUS GLAND -SEBACEOUS GLAND ■ROOT OF HAIR -HAIR FOLLICLE -ADIPOSE TISSUE -GLOMERULUS OF SWEAT GLAND "BULB OF HAIR "PAPILLA OF HAIR EPIDERMIS< papilla- derma < SUBCUTANEOUS AREOLAR TISSUE. Fig. 177. - Vertical Section of the Skin, showing Sebaceous Glands,. Sweat-glands, Hair, and Follicle, also Arrector Muscle. (Gerrish.) Sweat-glands. - All over the surface of the skin are minute openings or pores. These pores are the openings through which the sweat-glands pour their secretions upon the surface of the body. The sweat-glands are tubular glands with their blind ends coiled into little balls which are lodged in the true skin or subcutaneous tissue; from the ball the tube is continued as the excretory duct of the gland up through the true skin and epider- mis, and finally opens on the surface by a slightly widened orifice- Each tube is lined by a secreting epithelium continuous with Chap. XVII] ELIMINATION 295 the epidermis. The coiled end is closely invested by a mesh- work of capillaries, and the blood in the capillaries is only separated from the cavity of the glandular tube by the thin membranes which form their respective walls. The secretory apparatus in the skin is somewhat similar to that which obtains in the kidneys; in the one case the blood-vessels are coiled up within the tube, while in the other the tube is coiled up within the meshwork of blood-ves- sels. The sweat-glands are abundant over the whole skin, but they are most numerous on the palm of the hand and on the sole of the foot; in the groin, and especially in the axilla, they are larger than in other parts of the body. At a rough estimate, the whole skin probably possesses about two millions of these glands, and their combined secreting power is therefore very great. , Perspiration, or sweat. - The sweat is a watery, colourless liquid, slightly turbid, of a salty taste, with a strong, distinctive odour and an acid reaction. It is an excrement, the chief normal constituents of which are water, salts, fatty acids, a slight amount of urea, and a considerable amount of carbon dioxide. In vari- ous forms of kidney disease urea may be present in consider- able quantity, the skin supplementing to a certain extent the deficient work of the kidneys. - Quantity of perspiration. - Under ordinary circumstances, the perspiration that we are continually throwing off evaporates from the surface of the body without our becoming sensible of it, and is called insensible perspiration. When more sweat is poured upon the surface of the body than can be removed at once by evaporation, it appears on the skin in the form of scattered drops, and we then speak of it as sensible perspiration. Fig. 178. - Coii.ed End of a Sweat-gland. a, the coiled end; b, the duct; c, network of capillaries, inside which the sweat-gland lies. 296 ANATOMY FOR NURSES [Chap. XVII The amount varies to a great extent - with the condition of the atmosphere; the amount of exercise taken; the quantity of liquid ingested; the action of the kidneys. Variations also occur under the influence of mental emotions, the action of drugs, or are induced by certain diseased conditions. In general we may say the amount is about one quart (0.946 litre) in twenty- four hours. In addition to being a means of excretion, the sweat is of great value as a regulator of the body heat. By evaporating from the surface the sweat cools the body. Less important functions of the skin. - Besides being an im- portant execretory organ, the skin is to a slight extent an absorb- ing organ. Some substances can be absorbed through the epi- dermic covering, but if the horny layers of the epidermis be removed by blistering, matters in solution readily pass into the blood-vessels in the true skin. Oily substances, especially when well rubbed in, are absorbed without removal of the epidermis. Oxygen in small amount is also taken in through the skin, but this gain to the body is counterbalanced by the carbon dioxide which is thrown off. There is still another function of the skin to be considered before closing this chapter, and that is the part it plays in regu- lating the temperature of the body. BODILY HEAT In order that the bodily functions may be properly performed, it is necessary for the body to maintain a certain temperature. Just as plants are killed by the frost, or withered by the heat of the sun, so our tissues die if the bodily temperature falls be- low, or rises above, a certain limit. Our bodies, however, differ from plants in that they generate and regulate their own tempera- ture, and possess the power of adapting themselves to extremes of external heat and cold, without necessarily suffering any vital injury. But, although the external temperature of the atmos- phere may vary considerably without hurting us, the bodily temperature must be kept at an average standard of 98.6° F. (37° C.) if we are to remain in a state of health. Slight variations are compatible with health, the temperature being normally a trifle higher after eating, and in the late afternoon, and lower Chap. XVII] ELIMINATION 297 late at night or in the early morning. This corresponds to the usual temperature ranges in fever, when the maximum is in the late afternoon, and the minimum m the early morning. Production of heat. - Heat in the body is produced by the chemical changes that are constantly going on in the tissues and by the friction of muscles and other organs. Wherever meta- bolic changes are taking place, there heat is set free. These changes take place more rapidly in some tissues than in others, and in the same tissues at different times. The muscles always manifest a far higher rate of activity than the connective tissues, and consequently the former evolve a larger proportion of the bodily heat than the latter. We might liken the different tissues of the body to so many fireplaces stored with fuel, the fuel in some of the fireplaces being more easily ignited and burning more rapidly than in others. The muscles and the secreting glands, especially the liver, are supposed to be the main sources of heat, as they are the seats of a very active metabolism. Loss of heat. - The heat thus continually produced is as con- tinually leaving the body by the skin and the lungs, and by the urine and feces. It has been calculated that in every 100 parts about: - 88 per cent is lost by conduction and radiation from the sur- face of the skin and the evaporation of the'perspiration. 9 per cent is lost by warming the expired air and the evapora- tion of the water of respiration. 3 per cent is lost by warming the urine and feces. Distribution of heat. - The blood, as we know, permeates all the tissues in a system of tubes or blood-vessels. Wherever oxidation takes place and heat is generated, the temperature of the blood circulating in these tissues is raised. Wherever, on the other hand, the blood-vessels are exposed to evaporation, as in the moist membranes in the lungs, or the more or less moist skin, the temperature of the blood is lowered. The gain and loss of heat balance one another with great nicety, and the blood, circulating rapidly, now through warmer, and again through cooler tubes, is kept at a uniform temperature of about 100° F. (37.8 C.). In this way the whole body is warmed in somewhat the same way as we warm a house, the warm blood 298 ANATOMY FOR NURSES [Chap. XVII in the blood-vessels heating the tissues, as the hot water in the hot-water pipes heats the rooms in water-heated dwellings. Regulation of heat.-We have seen that active changes in the body produce heat. The action of the muscles is a source of heat, the activity of the glands during digestion, the active changes taking place in the tissues during inflammation or suppuration, or the changes caused by some specific micro- organism, and we may say that there are normal and abnormal sources of heat. Normally, production of heat is balanced by loss of heat, and one regulator of this gain and loss is undoubtedly the skin. This is well seen in the case of muscular exercise. Every muscular contraction gives rise to heat, and yet during severe muscular exercise the temperature of the body does not rise, or rises only to a trifling extent. This is accounted for by the fact that when the muscular exertion causes the blood to circulate more quickly than usual, the blood-vessels in the skin dilate, the sweat-glands at the same time are excited to pour out a more abundant secre- tion, and the heated blood passing in larger quantities through the cutaneous vessels (which are kept well cooled by the evapora- tion of the perspiration), the general average temperature of the body is maintained. In exposure to variations of external temperature, the skin is the chief agent in regulating the heat of the body. Exposure to cold causes the blood-vessels in the skin to contract, the cold act- ing as a stimulus to the vasomotor nerves, which control the caliber of the cutaneous blood-vessels. As a result, less blood is sent to the surface to be cooled, and the average blood-tempera- ture is maintained. On the other hand, exposure to warmth causes the cutaneous blood-vessels to dilate, and more blood is sent to the surface to be cooled. Briefly, when the external temperature is high, the cutaneous blood-vessels dilate, and the sweat is also usually poured out upon the surface of the skin; when the external temperature is low, the cutaneous blood-ves- sels contract, and the skin usually remains dry. By clothing we can aid the functions of the skin and the main- tenance of heat; though, of course, clothes are not in themselves sources of heat. The object of clothing is, in winter, to prevent conduction, radiation, and evaporation of heat from the skin, Chap. XVII] ELIMINATION 299 and in summer to promote it. Of the materials used for clothes, linen is a good conductor; calico or muslin not quite so good, while wool, silk, and fur are all bad conductors. Pyrexia. - In pyrexia, or fever, the rise of body temperature is due to causes which increase the metabolism of the tissues beyond the normal, with the result that there is a marked increase in heat production. At the same time there is an increase in heat elimination, but the elimination is not increased in proportion to the heat production. The result is a rise in temperature. In fever the heat elimination, while greater than in health, is not uniformly distributed over the body, but is in marked excess in some portion. Witness the hot, dry, flushed face, and pale, cold extremities, due to lack of proper distribution of vaso- motor tone. By sponging, baths, packs, etc., we attempt to cause the arteri- oles all over the body to dilate, the skin to perspire, and thus raise the heat elimination to such a point as nearly to balance the increased heat production, and thus bring about a fall in body temperature. When the change occurs spontaneously, we say the fever is " broken." If a very high temperature persists for any length of time, the metabolism of the tissues goes on at such a rapid rate that the capital of the body is soon exhausted. Every organ works with feverish activity, the heart and lungs increase their action, the pulse and respiration become more and more hurried, and con- sequently more and more feeble, until finally, unless relief is obtained, the patient dies of exhaustion. Subnormal temperature. - In some maladies the temperature falls distinctly below the normal. This is no doubt chiefly due to diminished metabolism. In cases of starvation the fall of temperature is very marked, especially during the last days of life. The diminished activity of the tissues first affects the cen- tral nervous system; the patient becomes languid and drowsy, and finally unconscious; the heart beats more and more feebly, the breath comes more and more slowly, and the sleep of uncon- sciousness passes insensibly into the sleep of death. 300 ANATOMY FOK NURSES [Chap. XVII SUMMARY Epidermis is a stratified epithelium 1. Superficial or horny a. Stratum corneum. b. Stratum lucidum. c. Stratum granulosum. a. Polyhedral cells. . b. Columnar cells. 2. Germinative . or Malpighian Skin, or Cutaneous Membrane Cutis vera is a layer of connective tissue T. Papillary layer - papillae. Bundles of fibrous and elastic tissue, with network of blood- vessels, lymphatics, and nerves. 2. Reticular layer Papillae are minute conical elevations of the cutis vera. They contain looped blood-vessels and tactile corpuscles. Tactile Corpuscles-Terminations of nerve-fibres found in the papillae, and are specially numerous where the sense of touch is well developed. ' Nails. Hairs with sebaceous glands. Sweat-glands. Appendages o£Skln ' Consist of clear, horny cells of epidermis. True skin forms a vascular, papillary bed or matrix for nail. Root of nail is lodged in a deep fold of the skin. - Nails grow from soft cells in Malpighian layer at root. Nails . . ' The hairs grow from the roots. The roots are bulbs of soft-growing cells contained in the hair follicles. Hair follicles are little pits developed in the cutis vera. Stem of hairs consist of three layers of cells: 1. Cuticle. 2. Fibrous substance. 3. Medulla. Arrector muscles are attached to true skin and to each hair follicle. Hairs . . Palms of the hands. Soles of the feet. Found all over body, except Fingers and toes. Last phalanges " Saccular glands the ducts of which usually open into a hair follicle, but may discharge separately on the surface of the skin. Lie between arrector muscles and hairs. Sebaceous Glands Found over entire skin surface except ' Palms. , Soles. Secrete sebum, a fatty, oily substance, which keeps the hah' glossy and the skin flexible. Chap. XVII] ELIMINATION 301 Tubular glands, consist of blind ends coiled in balls, lodged in subcutaneous tissue, and surrounded by a capillary plexus. Secrete sweat and discharge it by means of ducts which open exteriorly. (Po'res.) Abundant over whole skin, about 2,000,000. Sweat-glands Watery, colourless, turbid liquid, salty taste, distinctive odour, and acid reaction. Consists of water, salts, fatty acids, urea, and carbon dioxide. Average quantity, one quart in twenty-four hours. Sweat . . ' Atmosphere. Exercise. Quantity of liquid ingested. Action of kidneys. Amount influenced by Uses Removal of waste matters. Tends to reduce temperature of body by its evapora- tion. Normal temperature, 98.6° F. (37° C.). Slight variations compatible with health. Heat is produced by metabolic changes, friction of muscles, and other organs. Bodily Heat Heat lost by Skin. Lungs. Urine and feces. Distributed by the blood circulating through the blood- vessels. Regulated to a very great ex- f Increased secretion of sweat tent by the action of the skin } and evaporation of same. Pyrexia is caused by increased metabolism and insufficient heat elimination. Subnormal is caused by diminished metabolism. Abnormal Temperature 1. Excretes water, salts, fatty acids, urea, and carbon dioxide. 2. Absorbs oxygen, and under suitable conditions oily sub- stances and watery solutions. 3. Contains the tactile corpuscles. Seat of the sense of touch. 4. Protects or covers the deeper tissues. 5. Supports two appendages, viz. the hair and nails, and keeps itself flexible, and the hair glossy, by the secretion of sebum. 6. Regulates to some extent the temperature of the body. Functions of the Skin CHAPTER XVIII THE NERVOUS SYSTEM In the broad anatomical and physiological sense the nervous system is a collection of nervous tissue set apart as a special apparatus for inception, reception, and transmission of nerve impulses. This apparatus consists in general of a large collection of nerve-tissue called the brain; attached to it is the spinal cord, and passing from both are many nerve-trunks, going to all parts of the body, finally to terminate in minute structures called nerve- endings. Here and there along their course the nerve-fibres are in connection with partially discrete aggregations of nerve-tissue called nerve ganglia. If one looks at the minute histological make-up of the nervous system, it is seen to be made up of tiny microscopic elements called neurones. NEURONES Just as the anatomical and physiological unit of muscular tissue or connective tissue is either a muscle-cell or connective tissue cell, so the anatomical element of nervous tissue is the neurone. Thus the structure of the nervous system depends upon the position and relations of the neurones which compose it; and the activity of this system as a whole is the sum of the activities of its neurones. Although the neurones vary considerably in size and in form, there are certain structural characteristics which they all possess in common. The typical muscle or connective tissue cell con- sists of a simple cell of comparatively simple type; the neu- rone is somewhat more complex, and may be subdivided into three parts: - 302 Chap. XVIII] THE NERVOUS SYSTEM 303 (a) The nerve-cell proper. (6) The nerve-fibre. (c) The nerve-endings. These three parts make up a com- plete nervous entity called a neurone, and the entire nervous system is nothing but an aggregation of these neurones. (a) The nerve-cell. - The nerve- cell proper has a number of varieties as to size, shape, etc., but all present certain common characteristics. A typical nerve-cell consists of a mass of granular cytoplasm surrounding a large, well-defined nucleus, it in turn containing a nucleolus, and the whole mass of cytoplasm may in some cases be surrounded by a cell-wall. From the mass of cytoplasm there extend long, slender strands, or threads, of the cytoplasm called branches, or processes. One branch somewhat larger than the others, and seemingly more a part of the nerve- cell itself, is called the axis cylinder process (or neuraxon). The nerve-cell must have at least one branch and may have several more. If the cell have but one branch, that branch is the axis cylin- der process, and the cell is spoken of as a unipolar cell. If the cell has two branches, one is the axis cylinder process, and the cell is called bipolar; many branches, multipolar. The various branches, other than the axis cylinder process (or neuraxon) pass out from the cell-body for a short distance and then split up into smaller fibres called dendrites. These dendrites interlock with dendrites of other nerve-cells or with the terminal endings of nerve-fibres. This interlocking must not be under- Fig. 179. - Neurone. Ct Nerve-cell ; N, nucleus con- taining nucleolus; D, branches or dendrites; A, axis cylinder process merging into B, the nerve-fibre; ^terminals. (Sche- matic.) (Collins.) 304 ANATOMY FOR NURSES [Chap. XVIII stood as an anatomical continuation between the dendrites of two different nerve-cells, but that the dendrites of the two cells come so closely together that the nerve-impulse of the one cell is able to bridge the gap and set up nerve-impulses in the con- tiguous set of dendrites. The axis cylinder process, or neuraxon, may be distinguished from the other branches by the fact that it does not subdivide into dendrites after leaving the cell-body, but continues intact for a short distance, until it merges into a long, slender fibre called the nerve fibre. (6) Nerve-fibre. - While the nerve-fibre is really only the con- tinuation of the axis cylinder process that has undergone some change in structure, it is advis- able to describe the nerve-fibre separately as though it were a new subject. Nerve-fibres are of two kinds: medullated, or white fibres, and non-medullated, or gray fibres. Medullated fibre. - If one looks at a medullated nerve- fibre under the microscope, it is noted that its centre is a long cylinder, or rod, marked off with fine longitudinal stria- tions. Axis cylinder. - This cylin- der is continuous throughout the length of the nerve-fibres, and is called the axis cylinder, or axon. If we examine the nerve-fibre at a point close to its origin from the nerve-cell, it is seen that the axis cylinder is the direct continuation of that branch of the nerve-cell described above as the axis cylinder process, or neuraxon, the granular cytoplasm of the axis cylinder process gradually fading away as the axis cylinder process merges into the axis cylinder of the nerve-fibre, and at the same time the longitudinal striations of the axis cylinder of the nerve pass up indistinctly into the axis cylinder process of the nerve-cell to be lost in the body of the cell itself. Fig. 180.--Nerve-fibres, a, nerve- fibre, showing complete interruption of the white substance; b, another nerve- fibre with nucleus. In both these nerve- fibres the white substance is stained black with osrnic acid, and the axis cylinder is seen running as an uninter- rupted strand through the centre of the fibre, c, ordinary nerve-fibre unstained; a, e, smaller nerve-fibre; f, varicose nerve-fibre; g, non-medullated nerve- fibres. Chap. XVIII] THE NERVOUS SYSTEM 305 Medullary sheath.-Immediately surrounding the axis cyl- inder of the nerve-fibre is a sheath, or covering, of a semi-fluid, fatty substance called the medullary, or myelin sheath, or sheath of Schwann. It is to the refraction of light from this fatty substance that medullated nerve-fibres owe their white colour. Neurilemma. - External to the medullary sheath is a thin membrane completely enveloping the nerve-fibre and forming its outer covering called the neurilemma. Nodes of Ranvier. - At regular intervals along the course of a medullated nerve-fibre there are noted ring-like constrictions about the nerve-fibre dividing the nerve-fibre into a series of links, as it were. These constrictions are the nodes of Ranvier. At each node of Ranvier the constriction is due to a loss of continuity or absence of the medullary sheath, thus allowing the neurilemma to dip in, so to speak, and come in direct contact with the axis cylinder. Thus at each node of Ranvier the nerve- fibre is smaller in diameter, this change in diameter being entirely at the expense of the medullary sheath, the axis cylinder being unchanged. In each internode (portion of nerve-fibre between two adjacent nodes of Ranvier) the neurilemma is seen to have a nucleus. Medullated nerve-fibres may be very long (many inches), but the diameter is very minute, varying from -y^oo micromillimetres) to inch (17 micromillimetres). Non-medullated fibre. - Non-medullated nerve-fibres or, as they are sometimes called, the fibres of Remak, do not differ in any respect from the medullated nerve-fibres save in the absence- of the medullary sheath, the axis cylinder being directly invested by the neurilemma. Owing to the absence of the refracting medium (the medullary sheath), the non-medullated fibres do not appear white, but present a grayish or yellow colour. (c) Nerve-endings.-Nerve-fibres may end in several ways. If the nerve-fibre is to terminate while still lying in the mass of the nervous system, its axis cylinder may split up at the termina- tion into a number of short filaments called end arborizations, which interlock with the dendrites of another neurone, or the axis cylinder may send out side branches along its course (collaterals) which interlock with dendrites. Thus the individual neurone we are studying would serve only as a relay station. 306 ANATOMY FOR NURSES [Chap. XVIII Eig. 181. - Sensory Nerve Terminations in Stratified Pavement Epi- thelium. (Kirkes.) At the periphery of the body a nerve-fibre may end in one of four ways: - (1) Inter-epithelial arborizations. (2) Motor plates. (3) Various tactile corpuscles. (4) Special sense organs. (1) Inter-epithelial arborizations. - This is the most common mode of ter- mination of sensory nerves. The nerve- fibres pass to the surface either in the skin or mucous membrane; the neuri- lemma and medullary sheath disappear, the naked axis cylinder subdividing into minute end arborizations that ramify between the epithelial cells of the sur- face of the body. This method is the one in which nerves terminate in various glands, hairs, teeth, tendons, etc. (2) Motor plates. - A nerve intended to stimulate a muscle to activity termi- nates by a subdivision of the axis cylin- der (the neurilemma and medullary sheath fading out), each branch of the axis cylinder ending in a flat nodule of granular material lying on the muscle fibre. This terminal mass is the motor plate. (3) Various tactile corpuscles. -Some sensory nerves end in Fig 182. - Pacini's Cor- puscle. a, stalk; b, nerve- fibre entering it; a, d, con- nective-tissue envelope; e, axis-cylinder, with its end divided at f. (Collins.) Chap. XVIII] THE NERVOUS SYSTEM 307 the surface of the body in small oblong or rounded bodies, which seem to be especially designed for the sense of touch. There are several different varieties with probably differentiated functions. The different forms are known by separate names: (1) Corpuscles of Pacini, (2) tactile cor- puscles of Meissner, (3) tactile corpuscles of Krause, (4) tactile menisci, (5) cor- puscles of Golgi. (4) Special Sense Organs. - Some of the highly complex special sensations need very complex end organs for their reception: the organ of Corti, for the auditory nerve, and the rods and cones of the retina may be cited as examples. Nature of nerve impulse. - Having examined the make-up of a complete nervous entity (the neurone), it now seems best to study the nature of nerve-impulses. Just what is the nature of a nerve-impulse is difficult to answer. We know that nerve-fibres may be stimulated by several means, and the practical result is similar to the result obtained were the nerve stimulated by the natural physiological impulse. The nerve-fibre has no power to initiate a nerve-impulse, but serves merely as a conveyor of that impulse which has been started either in the end organs or in the nerve-cell. Artificial nerve stimulation. - There are four means usually applied to the artificial stimulation of a nerve-fibre, viz.: chemical, thermal, mechanical, and electrical, - the latter the most usual. That the true physiological impulse is none of these can be readily proven (see any standard work of physi- ology).. Physiological nerve stimulation. - The best explanation is that the true nature of nerve-impulse is a physical molecular vibration set up either in the nerve-cell or the end organs and transmitted along the nerve-fibre. Direction of nerve-impulse.-If a nerve be stimulated arti- ficially, the impulse will travel in either direction, but manifest activity results only from that portion of the impulse that travels in the physiological direction, for it is only the impulse travel- Fig. 183. - A, tactile corpuscle ; b, nerve. (Col- lins.) 308 ANATOMY FOR NURSES [Chap. XVIII ling in the right direction that finds a suitable outlet for its mani- festations. Afferent and efferent neurones. - From the previous para- graph it is deduced that the neurones are divided into two great classes: those in which the physiological direction for nerve- impulses to travel along the nerve-fibre is from the nerve-cell to the nerve-endings, called efferent neurones; and those in which the impulses travel in the reverse direction, afferent neurones. Fig. 184. - Section of the Internal Saphenous Nerve. Stained in osmic acid and subsequently hardened in alcohol. Drawn as seen under a very low mag- nifying power. (G. A. S.) ep, epineurium, or general sheath of the nerve, consist- ing of connective tissue separated by cleft-like areolae, which appear as a network of clear lines, with here and there fat-cells,/, f, and blood-vessels, v.; per, perineurium, or particular sheath of funiculus; end, endoneurium, or connective tissue within funiculus, embedded in which are seen the cut ends of the medullated nerve-fibres. The fat-cells and the nerve-fibres are darkly stained by the osmic acid. The most striking example of efferent neurones are those ending in muscle fibres; hence the efferent neurones are often spoken of as motor fibres, although motion is the manifestation of but a class of efferent neurones. On the other hand, afferent fibres are often spoken of, for similar reasons, as sensory. Cen- tripetal for afferent and centrifugal for efferent are other names sometimes used. Chap. XVIII] THE NERVOUS SYSTEM 309 Speed of nerve-impulses. - The speed at which an impulse travels along an afferent nerve-fibre is found to be about 140 feet (42.6 m.) per second. The efferent impulses travel some- what slower, 110 feet (33.5 m.) per second. Formation of nerve-trunks. - The nerve-fibre of each neurone is, as has been already described, of microscopic diameter, but when a number of these nerve-fibres are. bound together in a bundle, we have the plainly visible nerve-trunks, or nerves, such as are seen in dis- sections of the body. Nerves are whitish cords which arise from the cerebro-spinal axis, and branching as they go, are distributed to all parts of the body. Every organ and tissue has thus its supply of nerves connecting it with the brain or spinal cord. Between the nerve-fibres is a small amount of con- nective tissue which serves not only to bind the fibres together into bundles, or funiculi, but also to carry to or from the fibres the blood-ves- sels and the lymphatics necessary for their nutri- tion. Connective tissue also surrounds these bundles in the form of a sheath. The smaller nerves may con- sist of a single funiculus; but the larger nerve-trunks contain several funiculi united by connective tissue and surrounded by a common sheath of the same material. Fig. 185.-Diagram illustrating the General Arrangement of the Cerebro- spinal System. 310 ANATOMY FOR NURSES [Chap. XVIII Although the nerves branch frequently throughout their course, and these branches often meet and fuse with one another, or with the branches of other nerves, yet each nerve-fibre always remains quite distinct, never branching until it reaches its ter- mination, and never uniting with other nerve-fibres. The nerve- trunk is thus merely an association of individual fibres which proceed together towards the periphery. At any time one or more individual fibres may leave the main body and pass to their terminations, or may join another nerve; but in any case each fibre always remains perfectly distinct. Ganglia. - The cell-bodies, from which the axis cylinder of the peripheral nerve-fibres arise, are not scattered promiscuously throughout the body, but are gathered together in certain definite regions or groups. These form the gray matter of the cerebro- spinal axis and the ganglia. A ganglion is a small collection of cell-bodies connected by means of nerve-fibres and dendrites with other ganglia, and with the central nervous system. The ganglia may be divided into two large classes, the spinal and the sym- pathetic ganglia.1 (The spinal ganglia will be considered later.) THE SYMPATHETIC SYSTEM The term "sympathetic system" is used to designate a group of nerves and ganglia that differ somewhat in their functions from the other nerves and ganglia of the body, to which the term " cerebro-spinal system" has been applied. The ganglia and nerves of the so-called sympathetic system do not form an independent nervous system, for each ganglion is intimately connected by means of nerve-fibres with the rest of the nervous system, the whole forming an interdependent apparatus. The sympathetic ganglia consists of a double chain of ganglia, placed on each side of the spinal column, and united to each other by longitudinal filaments. The fibres that arise from them are mostly of the non-medullated variety. The sympathetic nerves are distributed to the viscera and blood-vessels, of which the movements are involuntary, and the general sensibility obtuse. They form networks or plexuses upon the heart, about the stom- 1 Isolated ganglia are also found in the course of some of the cranial nerves, and in some of the organs of special sense. Chap. XVIII] THE NERVOUS SYSTEM 311 ach, and other viscera in the trunk; they also enter the cranium, send branches to the. organs of special sense, and in particular influence the pupil of the eye. In the sympathetic ganglia the relation of the neurones is such that each nerve-fibre, arriving at the ganglion from the spinal cord, is brought into contact with several other neu- rones which lie wholly in the sympathetic sys- tem. Thus an efferent impulse, passing along an axis cylinder from the cord, may pass to the dendrites of several sympathetic cells, and then by their axis cylin- ders to the smooth muscles of the viscera, or to similar endings. As a result the impulse is distributed over an area supplied by several sympathetic neurones. Similarly, sensory im- pulses, originating in any part of the area supplied by a particular group of sympathetic neurones, may be trans- mitted to a single affer- ent dendrite which connects with the axis cylinders of several sympathetic cells. Fig. 186. - General View of the Sym- pathetic System. 1, 2, 3, cervical ganglia; 4, 1st thoracic ganglion; 5, 1st lumbar ganglion; 6, 7, sacral ganglion; 9, 9, cardiac nerves; 13. branch of pneumo-gastric nerve-ending in semi- lunar ganglion; 14, epigastric plexus. 312 ANATOMY FOR NURSES [Chap. XVIII These relations can best be understood by studying the accom- panying diagram (Fig. 187). Function of sympathetic system. - The principal action of the sympathetic is to supply: - (1) Sensations and motion to the organs of nutrition; thus the peristaltic movements of the stomach and intestines, the contraction of the gall-bladder, etc., together with the sensory stimuli of the viscera, are all produced by the sympathetic. (2) Secretion by the various glands of the body are reg- ulated by the sym- pathetic. (3) To the blood- vessels the sympa- thetic sends fibres that form plexuses about the vessels (arterioles especially) terminating in the mus- cular tissue of their walls, thus regulating their degree of con- traction and dilation. Those that dilate the vessels are called vaso-dilators; those that contract, the vaso-constrictors; collec- tively, the fibres regulating the contraction and dilatation of the arteries are called vasomotor nerves. Other fibres go to the heart to hasten its activity - cardiac accelerator (cardiac inhibitory are derived from pneumogastric). (4) Fibres to some of the special senses, such as those that regulate the pupil of the eye, etc. Fig. 187. -• Diagram showing the Relation of the Cerebro-spinal to the Sympathetic .Neu- rones. A, a medullated fibre, coming from cerebro- spinal system and dividing into numerous branches on reaching a sympathetic ganglion. These branches connect with those of the cells. B, B, in the ganglion, and these cells send their non-medullated fibres to supply the viscera, C, C, C, C. THE CEREBRO-SPINAL SYSTEM1 The cerebro-spinal system consists of the (1) spinal cord with its branching nerves and their ganglia, (2) the brain. 1 In defining the sympathetic system the student was cautioned to bear in mind that the cerebro-spinal system and sympathetic system were inter- communicating and interdependent parts of a whole and are described separately only for convenience. Chap. XVIII] THE NERVOUS SYSTEM 313 Spinal cord.-The spinal cord is that portion of the nervous system lodged within the spinal canal of the verte- bral column. It consists of a collection of gray (nerve-cells) and white (nerve-fibres) sub- stance, extending from the foramen magnum of the skull, where it is continuous with the medulla oblongata of the brain to about the second lumbar vertebra, where it tapers off into a fine thread. Before its termination it gives off a num- ber of fibres which form a tail- like expansion, called the cauda equina. Like the brain, the spinal cord is protected and nourished by three membranes. These membranes have the same names and practically exercise the same functions as those enveloping the brain (for de- scription of which see page 318). The outer membrane is not attached to the walls of the spinal canal, being separated from them by a certain quantity of areolar and adipose tissue, and a network of veins. Therefore the spinal cord does not fit closely into the spinal canal, as the brain does in the cranial cavity, but is, as it were, suspended within it. It diminishes slightly in size from above downwards, with the exception of presenting two Tig. 188.- Base of Brain, Spinal Cord, and Spinal Nerves. - V, 5th nerve; VI, 6th nerve; VII, a, facial nerve, b, auditory nerve; VIII, pneumo- gastric nerve; VIII, a, glosso-pharyn- geal, b, spinal accessory; IX, hypoglos- sal ; c1-c7, cervical nerve roots ; D'-Di2, dorsal nerve roots ; L'-L5, lumbar nerve roots; S4, S5, 4th and 5th sacral nerves; Cocc, coccygeal nerves; B.P., brachial plexus; L.P., lumbar plexus; S.P., sacral plexus; Sa, b, c, cervical sym- pathetic ganglia. 314 ANATOMY FOR NURSES [Chap. XVIII enlargements in the cervical and lumbar regions, where the nerves are given off to the arms and legs respectively. It is usually from sixteen to seventeen inches (400 to 425 mm.) long, and has an average diameter of three-fourths of an inch (19 mm.). The spinal cord is almost completely divided into lateral halves by an anterior and posterior fissure, the anterior Fig. 189. -Transverse Sections of the Spinal Cord at Different Levels Twice the natural size. (Gowers.) fissure dividing it in the middle line in front, and the posterior fissure in the middle line behind. In consequence of the presence of these fissures, only a narrow bridge of the substance of the cord connects its two halves, and this bridge is traversed Chap. XVIII] THE NERVOUS SYSTEM 315 throughout its entire length by a minute central canal, - the canalis centralis. On making a transverse section of the spinal cord, the gray matter is seen to be arranged in each half in the form of a half-moon, or crescent, with one end bigger than the other, and with the concave side turned outwards. The con- vex sides of the gray matter in each half approach one another, and are joined by the isthmus, or bridge, which contains the central canal. The tips of each crescent are called its horns, or cornua, the front or ventral horns being thicker and larger than the dorsal. The white matter of the cord is arranged around and between the gray matter, the proportion of gray and white matter varying in different regions of the cord. . The white matter, as in the brain, is composed of medullated nerves, and the gray matter of cell-bodies and fine gray fibres (naked axis cylinder and dendrites), all held together and supported by delicate connective tissue. The majority of the medullated fibres run in a longitudinal direction. There is no real division between the brain and spinal cord, the brain being built upon the cord, and together they form the great nerve-centre or axis, - the cerebro-spinal - which, by means of the cranial and spinal nerves, is placed in connection with all parts of the body. THE SPINAL NERVES There are thirty-one pairs of spinal nerves, arranged in the following groups, and named from the region through which they pass. They are: - Cervical 8 pairs. Dorsal 12 pairs. Lumbar 5 pairs. Sacral . 5 pairs. Coccygeal 1 pair. The spinal nerves pass out of the spinal canal through the intervertebral foramina, the openings between the vertebrae spoken of in the lesson on the bones of the spine. Each spinal nerve has two roots, a ventral root and a dorsal root The fibres connected with these two roots are collected into one bundle, and form one nerve just before leaving the canal 316 ANATOMY FOR NURSES [Chap. XVIII through the intervertebral openings. Before joining to form a common trunk, the fibres connected with the dorsal root present an enlargement, this enlargement being due to a ganglion, or small nerve-centre. The fibres of the ventral root arise from the gray matter in the ventral horn, and are direct prolongations from the cell-bodies there. The fibres of the posterior root arise from the cells composing the enlargement or ganglion of the posterior root and pass toward the periphery; each cell of the ganglion, besides sending toward the periphery the nerve-fibres just described, sends a branch along the posterior root up into the gray matter of the posterior horn, there to break up into branches articulating with other cells or dendrites. All the fibres making up the ventral root are efferent fibres, and convey nervous impulses from the spinal cord to the periphery. The fibres making up the dorsal root are afferent fibres, and convey nervous impulses from the periph- ery to the spinal cord. Fig. 190. - Diagram of Nerve Roots emerging from Spinal Cord. P.R. posterior root. Sp.G. posterior root ganglion. A.R. anterior root. (Schematic.) (Collins.) It should be borne in mind that the dorsal roots contain only sensory fibres, and that these fibres always have their origin outside of the cord (fie. in the spinal ganglia) while the ventral roots contain only motor fibres, and these have their origin within the central nervous system. This is true also of the Chap. XVIII] THE NERVOUS SYSTEM 317 cranial nerves, except that in these either one root or the other is often entirely lacking. The relations of the roots, fibres, and so forth, can be best understood from a study of the accompanying diagrams (Figs. 190 and 191). Degeneration and regeneration of nerves. - Since, as has been stated in Chapter II, the nucleus is essential for the nutrition of the whole cell, it follows that if the processes of a neurone are cut off, they will suffer from malnutrition and die. If, for instance, a spinal nerve be cut, all the peripheral part will die, since the fibres composing it have been cut off from their cell-bodies situated in the cord, or in the spinal ganglia. The divided ends of a nerve that has been cut across readily reunite by cica- tricial tissue, - that is to say, the connective tissue framework unites, but the cut ends of the fibres themselves do not unite. On the con- Fig. 191. - Degeneration of Spinal Nerves and Nerve-roots after Section. A, section of nerve trunk beyond the ganglion, B, section of anterior root; C, section of posterior root; D, excision of ganglion; a, anterior root; p, posterior root; g, ganglion. trary, the peripheral or severed portion of the nerve begins to degenerate, the medullary sheath breaks up into a mass of fatty molecules and is gradually absorbed, and finally the axis cylinder also disappears. In regeneration, the new fibres grow afresh from the axis cylinder of the cen- tral end of the severed nerve-trunk, and penetrating into the peripheral end of the neurilemma, grow along this as the axis cylinder of the new nerve, each axis cylinder becoming after a time surrounded with a medul- lary sheath. Restoration of function in the nerve may not occur for several months, during which time it is presumed the new nerve-fibres are slowly finding their way along the course of those which have been destroyed. Functions of spinal cord: - (a) Conduction, or the conveyance of impulses and sensations between the centres and the periphery. (6) Reflex action, i.e. the origination of an impulse or action 318 ANATOMY FOR NURSES [Chap. XVIII in response to a stimulation from the periphery, without of necessity involving the brain in the act or even without con- sciousness of the reflex act on the part of the individual. (c) Augumentation, or a resulting effect greater than the exciting cause (see Fig. 187). (d) Automatic acts, i.e. acts set up primarily in the cells of the cord by the cells themselves, and not as a result of stimula- tion by brain cells (voluntary acts) nor as result of peripheral stimulation. (e) Coordination, or the adjusting of the workings of different parts of the body to one another. (/) Inhibition of reflex acts. - If every outside stimulation were allowed its full effects in the setting up of reflex acts, the body would be on "the jump" all the time. This overactivity is checked unconsciously by the cells of the spinal cord endowed with this function. • 0) Transference, i.e. an apparent transferring of impulses from one set of fibres to another. The brain, the most complex and largest mass of nervous tissue in the body, is contained in the complete bony cavity formed by the bones of the cranium. It is covered by three membranes (also named meninges),-the dura mater, pia mater, and arachnoid. The dura mater, a dense membrane of fibrous connective tissue, lines the bones of the skull, forming their internal peri- osteum, and covers the brain. It sends numerous prolonga- tions inward for the support and protection of the different parts of the brain; it also forms sheaths for the nerves passing out of the skull. It may be called the protective membrane. The pia mater is a delicate membrane of connective tissue, containing an exceedingly abundant network of blood and lymph vessels. It dips down into all the crevices and depres- sions of the brain, carrying the blood-vessels which go to every part. It may be called the vascular or nutritive membrane. The arachnoid is a delicate serous membrane which is placed outside the pia mater. It passes over the various eminences BRAIN AND CRANIAL NERVES Chap. XVIII] THE NERVOUS SYSTEM 319 and depressions on the surface of the brain, and does not dip down into them like the pia mater. Beneath it, i.e. between it and the pia mater, is a space (sub-arachnoid space) in which is a certain amount of fluid. The sub-arachnoid space at the base of the brain is of considerable size, and contains a large amount of this clear, limpid fluid, called the cerebro-spinal fluid. This fluid probably acts as a sort of protective water- cushion to the delicate, nervous structure, and prevents the effects of concussions communicated from without. The brain is a semi-soft mass of white and gray matter. The white matter consists of very small, medullated nerve-fibres, running in various directions, and supported by a delicate con- nective tissue framework. The gray matter consists of cells and fine gray fibres, also supported by connective tissue. The brain is divided into four principal parts: the cere- brum, the cerebellum, the pons Varolii, and the medulla oblon- gata. The medulla oblongata. - The medulla oblongata is contin- uous with the spinal cord, which, on passing into the cranial cavity through the foramen magnum, widens into an oblong- shaped mass. It is directed backwards and downwards, its anterior surfaces resting on a groove in the occipital bone, and its posterior surface forming the floor of a cavity between the two halves, or hemispheres, of the cerebellum. The cavity, called the fourth ventricle, is an expanded continuation of the tiny central canal which runs throughout the whole length of the spinal cord. Functions of the medulla oblongata. - Besides the various functions already described under the enumerations of the functions of the spinal cord, the medulla is the seat of several highly important or vital centers. The principal ones are: - (1) The respiratory centres for regulating the function of respiration. (2) Cardiac centres to control rate and force of heart's action. (3) Vasomotor centre to regulate size of arterioles in any part of the body, thus controlling the amount of blood furnished to that part. (4) Other centres, such as the vomiting centre, heat control- ling centre, etc. 320 ANATOMY FOR NURSES [Chap. XVIII The student will readily appreciate that, the medulla being the seat of such important centres as those controlling respiration and heart's action, if the medulla be seriously injured, death will result. Execution by hanging aims not at strangling the victim, but at dis- locating the atlas on the axis and causing the odontoid process of the axis to crush the medulla, an effect brought about by the sudden jerk the vic- tim receives when the "drop" is sprung. Cerebellum. -The cerebellum, or "little brain," occupies the lower and back of the skull cavity, overhanging the medulla oblongata. It is of a flattened, oblong shape, and measures from three and a half inches to four inches (87 to 100 mm.) Fig. 192.--The Base of the Brain. 1, longitudinal fissure; 2, 2, anterior lobes of cerebrum; 3, olfactory bulb; 7, optic commissure; 9, 3d nerve; 11, 4th nerve; 13, 5th nerve; 14, crura cerebri; 15, 6th nerve; 16, pons Varolii; 17, 7th nerve; 19, Sth nerve; 20, medulla oblongata; 21, 9th nerve; 23, 10th nerve; 25, 11th nerve; 27, 12th nerve; 28, 29, 30, 31, 32, cerebellum. transversely, and from two to two and a half inches (50 to 63 mm ) from before backwards. It is divided in the middle line into two lateral lobes, or hemispheres, and a median lobe, by a central depression, each lobe being subdivided by fissures into smaller portions. The surface of the cerebellum is traversed by numer- ous curves, or furrows, which vary in depth. In the medulla oblongata the gray matter is placed in the interior, and the Chap. XVIII] THE NERVOUS SYSTEM 321 white on the exterior; in the cerebellum the gray is on the out- side and the white within. Peduncles of cerebellum. - The cerebellum is connected with the rest of the cerebro-spinal system by many white nerve- fibres grouped in bundles called the peduncles. The peduncles are arranged in three pairs. The anterior (superior) peduncles pass forward from the cerebellum to enter into the cerebrum. The posterior (inferior) peduncles pass down to the medulla, where they are known as the restiform bodies. The middle pair pass into and make up the larger portion of the pons Varolii, thus serving as a means of intercommunication between the two halves of the cerebellum. Thus it is seen that the cerebellum communicates most freely with the entire cerebro- spinal system. Functions of the cerebellum. - Disease or destruction of the cerebellum apparently exerts no malign influence on sensory nerves nor upon the intellect. The motor system is, however, profoundly deranged. Motion is itself not destroyed, but coor- dination is so interfered with that movements of one part of the body cannot be adapted to other parts. Pigeons deprived of the cerebellum will fly if thrown from a roof, but the delicacy of the coordination being lost, they turn a series of somer- saults in the air and soon fall to the ground. Pons Varolii. - The pons Varolii, or bridge of Varolius, lies in front of the upper part of the medulla oblongata. It consists of interlaced transverse and longitudinal white nerve-fibres intermixed with gray matter. The transverse fibres are those derived from the middle peduncles of the cerebellum and, as already stated, serve to join its two halves. The longitudinal fibres join the medulla with the cerebrum. Functions of pons Varolii. - The pons is merely a bridge of union between the two halves of the cerebellum and a bridge between the medulla and the cerebrum. Cerebrum. - The cerebrum is by far the largest part of the brain. It is egg-shaped, or ovoidal, and fills the whole of the upper portion of the skull. It is almost completely divided by the median fissure into two hemispheres, the two halves, how- ever, being connected in the centre by a broad, transverse band of white fibres called the corpus callosum. 322 ANATOMY FOR NURSES [Chap. XVIII The longitudinal fibres of the medulla oblongata, passing through the pons Varolii, become visible in front of the pons Fig. 193. -External View of Outer Side of Right Cerebral Hemi- sphere, showing Rolando, Sylvian, and Parieto-occipital Fissures to- gether with Principal Convolutions. (Collins.) as two broad; diverging bundles. These two bundles form what are called the crura cerebri; or pillars of the brain, and are situated on the under surface of each hemisphere. Forming the floors of the ventricles (to be described later), lodged in the crura Fig. 194. - Mesial View of Left Cerebral Hemisphere showing Rolandic and Parieto-occipital Fissures, together with the Principal Convolu- tions. (Collins.) Chap. XVIII] THE NERVOUS SYSTEM 323 cerebri, and scattered in their neighbourhood, are irregularly shaped masses of gray matter, intricately connected with one another and with the gray matter in the medulla oblongata. Surface of cerebrum. - The surface of each cerebral hemi- sphere is subdivided into five lobes by three fissures, which are always present. The fissures are the - (1) Fissure of Rolando. (2) Fissure of Sylvius. (3) Parieto-occipital fissure. The five lobes are named as follows: - (1) Frontal lobe. (2) Parietal lobe. (3) Tempero-sphenoidal lobe. (4) Occipital lobe. (5) Central lobe, or Island of Reil. Convolutions. - The surface of the cerebrum is further sub- divided by a number of shallower depressions called sulci. The brain surface between the sulci is thus thrown into folds, or ridges, called convolutions, the folds, or convolutions, being deeper and more numerous in some brains than others; the whole of the convoluted surface is composed of gray matter, i.e. of cell-bodies and naked processes. The lobes of cerebrum. - (1) The frontal lobe is that portion of the cerebrum lying in front of the fissure of Rolando, and usually consists of four main convolutions. (2) Parietal lobe is bounded in front by the fissure of Rolando, and behind by the parieto-occipital fissure. (3) Tempero-sphenoidal lobe lies below the fissure of Sylvius and in front of the occipital lobe. (4) Occipital lobe occupies the posterior extremity of the cerebral hemisphere. When one examines the external surface of the hemisphere, there is no marked separation of the occipital lobe from the parietal and tempero-sphenoidal lobes that lie to the front; but when the surface of the longitudinal cleft is examined, the parieto-occipital fissure serves as a boundary anteriorly for the occipital lobe. (5) Central lobe, or Island of Reil, is not seen when the sur- face of the hemisphere is examined, for it lies within the fissure 324 ANATOMY FOR NURSES [Chap. XVIII of Sylvius, and the overlying convolutions of the parietal, tem- pero-sphenoid, and frontal lobes must be lifted up before the central lobe comes into view. Ventricles of the brain. - In describing the spinal cord, ref- erence was made to the canalis centralis, or central canal, being a minute canal running through the centre of the cord throughout its entire length, thus converting the cord into a tube with exceedingly thick walls but very small internal caliber. In the brain proper this same central channel persists, and just as the walls or solid portions of the brain are directly continuous with the wall or solid portion of the spinal cord, so is the internal hollow of the brain directly continuous with the hollow or central canal of the cord. The cavity in the brain presents some marked differences to that of the cord; while the latter is a straight, fairly uniform canal of very small diameter, the former is at some points very narrow, and at others much widened out so as to form quite good-sized chambers, and these chambers are called the ventricles of the brain. These ventricles are filled with cerebro-spinal fluid, just as the canal of the cord is likewise filled with the same material. The ventricles (four in number) are known numerically. The most posterior is the enlargement or expansion of the central canal, occupying the substance of the medulla oblongata, and is called the " fourth ventricle." Leading forward from the anterior end of the fourth ventricle, the caliber of the canal again narrows to a very small diameter; the tube, on reaching the brain substance uniting the two halves of the cerebrum, again expands into a somewhat smaller chamber, called the '/third ventricle." The small canal already mentioned as joining the third and fourth ventricles lies between the two crura-cerebri, and is known as the aqueduct of Sylvius. Toward the forward end of the third ventricle there are noted two small channels, the foramina of Munroe, one on either side leading in a direction forward, upward, and outward, each fora- men leading into a very large ventricle occupying the centre of its corresponding cerebral hemisphere, called the lateral ventricles. The student will thus see that both the brain and spinal cord are really hollow. In some portions, however (as the spinal Chap. XVIII] THE NERVOUS SYSTEM 325 cord), the interior cavity is so minute and the walls so exceed- ingly thick that the cavity is a negligible quantity, and the mass can practically be considered as solid; on the other hand, in the case of the ventricles, especially the lateral ventricles, the cavity is large enough to occupy an appreciable space, and may become overdistended with cerebro-spinal fluid in certain con- ditions of disease. On the whole, the cavity of the brain and cord occupies a more or less central position, having its walls at any given point of about equal thickness; at certain points, however (the third and fourth ventricles especially), the cavity approaches so close to the surface that at these points one of its walls is thinned out to only a microscopic thickness. Localization of brain function. - All of our mental processes, including sensations, motions; and all the higher functions of memory, reasoning, etc., owe their existence to brain activity, and doubtless each class is referable to some definite area of the brain. This broad statement can only be made when we reason from analogy, for only a small portion of the brain, as yet, has been proven to be the seat of certain definite functions. The best understood is the motor area. Motor areas. - The surface of the brain assigned to the function of motion is the anterior portion of the parietal lobe and the posterior part of the frontal lobe, i.e. the gray matter immediately surrounding the fissure of Rolando. Sensory areas. - Common sensation is pretty generally con- ceded to lie in the posterior portion of the parietal lobe, while the centre for vision is assigned to the region about the posterior branch of the fissure of Sylvius. The hearing centre is in the tempero-sphenoidal lobe, and the speech centre is in the lower part of the frontal lobe. The seat of memory is attributed to the occipital lobe. THE BRAIN AS A WHOLE The whole brain appears to consist of a number of isolated masses of gray matter - some large, some small - connected together by a multitude of medullated fibres (white matter) arranged in perplexing intricacy. But a general arrangement 326 ANATOMY FOR NURSES [Chap. XVIII may be recognized. The numerous masses of gray matter in the interior of the brain may be looked upon as forming a more or less continuous column, and as forming the core of the central nervous system, while around it are built up the great mass of the cerebrum and the smaller mass of the cerebellum. This central core is connected by various bundles of fibres with the spinal cord, besides being, as it were, a continuation of the gray matter in the centre of the cord. It is also connected at its upper end by numberless fibres to the gray matter on the surface of the cerebrum. The average weight of the brain in the male is forty-nine and a half ounces (1403 grammes) in the female, forty-four ounces (1247 grammes). It appears that the weight of the brain in- creases rapidly up to the seventh year, more slowly to between sixteen and twenty, and still more slowly to between thirty and forty, when it reaches its maximum. Beyond this age the brain diminishes slowly in weight, about an ounce every ten years. The size of the brain bears a general relation to the capacity of the individual. Cuvier's brain weighed rather more than sixty- four ounces (1814 grammes), while the brain of an idiot seldom weighs more than twenty-three ounces (652 grammes). The number and depth of the cerebral convolutions also bear a close relation to intellectual power; babies and idiots have few and shallow folds, while the brains of men of intellect are always markedly convoluted. THE CRANIAL NERVES The vast majority of nerves pass out from the spinal cord, as the student has already noted, to go to all parts of the body to endow the parts with motion, sensation, etc. In addition, there are nerves which leave the brain and pass to their respective points of distribution without becoming an integral part of the spinal cord. They are largely nerves of special sensation as well as supplying the face with motion and common sensation, and are spoken of collectively as the cranial nerves. The cranial nerves, twelve in number on each side, arise.from the base of the brain and medulla oblongata (yide Fig. 192), and pass out 1 See page 385. Chap. XVIII] THE NERVOUS SYSTEM 327 through openings in the base of the skull. They are named numerically according to the order in which they arise from the brain. Other names are also given to them, derived from the parts to which they are distributed or from their functions. Taken in their order from before backwards, they are as follows:- 1. Olfactory (sensory). 2. Optic (sensory). 3. Oculomotor (motor). 4. Pathetic, or trochlear (motor). 5. Trifacial, or trigeminal (mixed, but mainly sensory). 6. Abducens (motor). 7. Facial (motor). 8. Auditory (sensory). 9. Glossopharyngeal (mixed). 10. Pneumogastric, or vagus (mixed). 11. Spinal accessory (motor). 12. Hypoglossal (motor). The olfactory nerve is the special nerve of the sense of smell. Its origin is in the olfactory bulb. Its peripheral fibres pass through the perforated plate of the ethmoid bone and are distributed to the mucous membrane lining the nasal chambers, while the central fibres pass back- ward to the brain. The optic nerve is the special nerve of the sense of sight. Its cell bodies are situated in the retinal coat of the eye. Part of its central fibres terminate in the same side of the brain, while the remainder cross to ter- minate in a similar region on the opposite side of the brain. This cross- ing of part of the fibres from both eyes forms the optic commissure. The oculomotor nerve supplies all the muscles of the eye except the superior oblique and the external rectus. It originates in the gray matter of the pons Varolii. The pathetic, or trochlear, nerve supplies only the superior oblique muscle of the eye. It arises close to the preceding nerve. The trifacial is the largest of the cranial nerves. Like the spinal nerves, it has two roots, - a dorsal, or sensory (upon which there is a sensory ganglion), and a ventral, or motor. The fibres from the two roots coalesce into one trunk, and then subdivide into three large branches: the oph- thalmic, the superior maxillary, and the inferior maxillary. The ophthal- mic branch is the smallest, and is a sensory nerve. It supplies the eyeball the lacrimal gland, the mucous lining of the eye and nose, and the skin and muscles of the eyebrow, forehead, and nose. The superior maxillary, the second division of the fifth, is also a sensory nerve, and supplies the skin of the temple and cheek, the upper teeth, and the mucous lining of 328 ANATOMY FOR NURSES [Chap. XVIII the mouth and pharynx. The inferior maxillary is the largest of the three divisions of the fifth, and is both a sensory and a motor nerve. It sends branches to the temple and the external ear; to the teeth and lower jaw; to the muscles of mastication; it also supplies the tongue with a special nerve (the lingual) of the sense of taste. The cell-bodies of the motor fibres are situated in the pons; while those of the sensory fibres, as in the case of the spinal nerves, are situated in a ganglion. This ganglion is called the Gasserian ganglion. The abducens nerve supplies the external rectus muscle of the eye. The facial nerve is the motor nerve of all the muscles of expression in the face; it also supplies the neck and ear. Its cells of origin, like those of the abducens nerve, are situated in the medulla. The auditory nerve is the special nerve of the sense of hearing. It arises from cells which compose the organ of Corti in the internal ear, to which its fibres are exclusively distributed. The glossopharyngeal nerve is distributed, as its name indicates, to the tongue and pharynx, being the nerve of sensation to the mucous mem- brane of the pharynx, of motion to the pharyngeal muscles, and the special nerve of taste to part of the tongue. The pneumogastric nerve has a more extensive distribution than any of the other cranial nerves, passing through the neck and thorax to the upper part of the abdomen. It contains both motor and sensory fibres. It supplies the organs of voice and respiration with motor and sensory filaments; and the pharynx, oesophagus, stomach, and heart with motor fibres (cardiac inhibitory). The spinal-accessory nerve consists of two parts: one, the spinal por- tion, and the other the accessory portion to the tenth nerve. It is a motor nerve supplying certain muscles of the neck. It differs from the other cranial nerves in arising from the spinal cord, but it leaves the skull by the same aperture as the pneumogastric and glossopharyngeal. The hypoglossal nerve is the motor nerve of the tongue. It will be observed that of the twelve pairs of cranial nerves four and a part of a fifth are distributed to the eye, viz. the optic, motor occuli, pathetic, abducens, and the ophthalmic branch of the fifth. The ear has one special nerve, the auditory, and is sparingly supplied with motor and sensory fibres from other nerves. The nose has also one special nerve, the olfactory, and is more abundantly supplied than the ear with motor and sensory fibres from other nerves. The tongue has two special branch nerves of taste, - the lingual, a branch of the fifth, and the glossal, a branch of the ninth; it has also its own motor nerve, the hypoglossal. Reflex acts. - The student doubtless can easily understand from the preceding portions of this chapter the general arrange- ment of the nervous tissues, and how simple impulses arising in brain cells, pass along nerve-fibres, and terminating in the Chap. XVIII] THE NERVOUS SYSTEM 329 end organs, produce, for example, a muscular contraction (mo- tor impulse), or how an outside stimulus applied to the skin will set up vibrations in suitable end organs to be transmitted along sensory nerve-fibres to end in sensory brain cells and pro- duce the appreciation by the mind of the fact that the stimu- lus has been applied. All of these are simple, straightforward functions of the neurones. There is a host of other more com- plex acts in which, for example, two or more neurones take part, which carry out a train of functions, each depending on the other, and may carry out their destiny so smoothly and accurately, so that the perception of the mind or consciousness of the act be entirely wanting, thus saving the brain an enormous amount or wear and tear. The simplest of these nervous mechanisms is the reflex arc, and the simplest form of nervous activity is 11 reflex action." Two neurones enter into the formation of a reflex arc, a sensory neurone and a motor neurone. On applying an appropriate stimulus to the peripheral end of the sensory neurone, an impulse is generated which passes along the sensory neurone to the nerve centre, and back again to the periphery by the motor neurone; and, since the motor neurone terminates in a muscle (or some similar mechanism), we get a muscular response as the indirect result of stimulating the sensory nerve. This is a reflex act, and usually the exchange between the sensory and motor impulse takes place in the spinal cord. The sensory impulse, after delivering its stimulus to the motor neurone, may continue on up the spinal cord to terminate in the brain and give to the individual the consciousness of the stimulus, or on the other hand, the sensory impulse, after arousing the motor act, may cease, and no impulse be transmitted to the brain, the individual thus being totally oblivious to the reflex act. Even if the sensory impulse goes to the brain, the consciousness of the sensation by the individual is always later in point of time than the reflex act. For example: If, without a person's knowledge that the experiment is to be tried, one's finger be pricked with a pin, the finger is instantly pulled back and the act is done before the individual is conscious of the pain. In this experiment the sensory impulse of the pin prick passed to the spinal cord, set up the motor action necessary to withdraw 330 ANATOMY FOR NURSES [Chap. XVIII the finger, and then passed on to the brain. Again, many sensory impulses produce their reflex without the brain bother- ing about the matter at all. An example of this is the act of walking. Walking is an exceedingly difficult accomplishment to learn, acquired in childhood only after laborious effort, not because the muscles are weak, but because the human individual, when erect, is in an exceedingly unstable state of equilibrium, and constant contraction and relaxation of groups of muscles is necessary to maintain the balance. Here the sensory impulses of being out of balance arouse motor impulses in first one set of muscles, then another, to restore the balance. At first this Fig. 195.-Reflex Arc. S, sensory neuron arising in tactile corpuscles. Af, motor neuron ending in muscle fibres. R, interlacing of dendrites. (Collins.) is only accomplished with mental appreciation of the perform- ance; later on one learns the trick, and the act of walking or standing upright is performed without a moment's thought or even consciousness of the difficult task we are doing purely by reflex activity. The kind of stimulus which will call forth the nerve-impulse depends on the peripheral termination of the afferent nerve, and the kind of response which an appropriate stimulus will call Chap. XVIII] THE NERVOUS SYSTEM 331 forth depends on the mode of termination of the efferent nerve. Thus, light falling on the retinal coat of the eye (the peripheral termination of the sensory nerve) generates an impulse which passes to the centre by the optic nerve, and returns again by the oculomotor nerve to the periphery; viz., the sphincter of the iris (the termination of the motor nerve), which by its contraction narrows the pupil. Hence arises the well-known phenome- non of the contraction of the pupil when light falls upon the eye. Or, again, food passing into the upper part of the intestine stimulates the sensory nerves there. The impulse passes to the spinal cord, is reflected from this centre toward the periphery, and passing along the motor nerve stimulates to contraction the appropriate muscular mechanism which causes a flow of bile into the intestine. Also stimulation of taste fibres in the mouth causes a reflex secretion of the salivary glands. Innumerable examples of this kind might be given. Indeed, since physical life has been well- defined as the continual response to external stimuli, reflex action, which is the chief method of response, is the most im- portant vital phenomenon peculiar to animals possessing any nervous system whatsoever. A careful study of Figs. 195 and 196 will make the typical reflex path perfectly intelligible to the student, and should on no account be omitted. All nervous action is fundamentally similar to this typical reflex action. Usually the number of neurones involved is greater, often very much greater, than two. The fewer the neurones, the simpler and more obviously machine-like the reaction. The more 'complex the path, the more uncertain and variable the reaction. When the path of the impulse does not involve the cerebrum, the reactions are unconscious and comparatively sim- ple; but if the cerebral cortex be involved, the passage of the nerve-impulse is accompanied by the phenomenon of conscious- ness, and the reaction may be exceedingly complex, uncertain, and long delayed. These are the characteristics of what we call voluntary reactions. But, although the phrase "reflex action" is usually confined to those actions which are involuntary and of which we are unconscious, yet all nervous action is essentially 332 ANATOMY FOR NURSES [Chap. XVIII the same, differing only in the complexity of the path followed by the impulse. We will now conclude with a review of the functions of the various parts of the nervous system. Fig. 196. - Diagram of Nervous System, a, a, cortex of cerebral hemispheres; b, b, cell body and dendrites of upper motor neurone, situated in cerebral cortex ; b', axis cylinder of upper motor neurone, branching at its termination near the dendrites of lower motor neurone, situated in the ventral horn of gray matter in the spinal cord ; B, axis cylinder of lower motor neurone passing to its termination in a volun- tary muscle fibre B"; C, cell body and dendrites of upper sensory neurone, situ- ated in the medulla oblongata; C', C', axis cylinders of upper sensory neurone, terminating in cortex ; c, cell body of lower sensory neurone, situated in the dorsal root ganglion ; c"', dendrite of lower motor neurone, conducting impulses from the periphery to the central nervous system ; c", long branch of lower sensory neu- rone, conducting impulses toward the brain; c' short branch of lower sensory neurone, conducting impulses direct to ventral horn. (For the sake of simplicity the connections with the cerebellum are omitted.) Chap. XVIII] THE NERVOUS SYSTEM 333 The nerves serve to connect the distant parts of the body with the central nervous system. The spinal ganglia contain the cells of origin of all the periph- eral sensory nerve-fibres. The sympathetic ganglia serve to distribute motor, and to collect sensory, impulses. Also in a few cases an afferent impulse may pass to a ganglion by the dendrites of one sympathetic neurone, and leave it to pass back again to the periphery by the axis cylinder of another, the spinal column not being included in the arc. Thus the sympathetic ganglia may occasionally act as a centre for reflex action. The spinal cord, medulla, and pons act as centres for the more simple reflexes. In the medulla there are also special centres which govern more complex muscular movements, such as the vasomotor centre, which controls the caliber of the blood-vessels, and hence the flow of blood to all parts of the body; and the respiratory centre, which coordinates the actions of the muscles of respiration. The cerebellum is a great coordinating centre for impulses passing from the cerebral cortex to the voluntary muscles. The cerebral cortex is involved in all conscious perceptions or sensations, in memory, and in the voluntary movements. Dif- ferent parts of the cortex have been shown to have different func- tions. Thus there are areas for visual and auditory sensations; areas which control the voluntary movements of various parts of the body, - the leg, the arm, the hand, etc., each having its separate area.1 SUMMARY Nerve-cell, unipolar, bipolar, multipolar. Axis cylinder. Myelin sheath. Neurilemma (nodes of Ravier). Medullated Neurone, a nervous entity consisting of Nerve- fibre f Axis cylinder. [ Neurilemma. „ T „ x 1 Non-medullated ' Inter-epithelial arborization. Muscle plates. Various tactile corpuscles. Special sense organs. T Nerve-endings ° 1 All the fibres passing to and from the cortex cross over to the other side of the body, so that an injury to one side of the brain causes paralysis of the opposite side of the body. 334 ANATOMY FOR NURSES [Chap. XVIII Nerve Impulse, a physical molec- ular vibration Afferent (periphery to brain). Efferent (brain to periphery). Nerve-trunks . . Bundles of nerve-fibres bound together to make funiculi. Funiculi bound together to make nerve-trunks. ' Ganglia - Collection of nerve-cells Spinal cord, 3 coverings, same as brain Cervical . 8 pairs. Dorsal • . 12 pairs. Lumbar „ . 5 pairs. Sacral . . 5 pairs. Coccygeal . 1 pairs. 31 pairs of nerves Medulla, seat of Respiratory centre. Cardiac centre. Vasomotor centre. Cerebellum Coordinates voluntary movements. A bridge of nerve-fibres connecting two halves of cerebellum and also medulla with cere- brum. Pons Varolii Cerebro- spinal System Frontal. Parietal. Occipital. Tempero- sphenoidaL Central. Brain, 3 coverings, dura mater, pia mater, arachnoid Lobes Rolandic. Sylvian. Parieto- occipital. Fissures Cerebrum, 2 hemispheres Convo- lutions Ridges on sur- face separated by sulci. Motion. Sensation. Speech. Hearing. Memory and higher functions. Functions seat of Chap. XVIII] THE NERVOUS SYSTEM 335 Canalis centralis of spinal cord. Fourth ventricle in medulla. Aqueduct of Sylvius between crura cerebri. Third ventricle in cerebral commissure. Ventricles and Cavities of Cerebro-spinal Axis Foramen of Monroe Channel leading from third ven- tricle to lateral ventricle. Lateral ventricles- Cavity of cerebral hemispheres. I. Olfactory. II. Optic. III. Oculomotor. IV. Pathetic. V. Trifacial. VI. Abducens. VII. Facial. VIII. Auditory. IX. Glossopharyngeal. X. Pneumogastric. XI. Spinal accessory. XII. Hypoglossal. Cranial Nerves Sympathetic System, consisting of Sympathetic ganglia. Intimately connected with cerebro-spinal system Sympathetic nerve-fibres, mostly non-medullated Sends motor impulses to involuntary muscles. Conveys sensations from viscera. Controls vasomotor system. Controls heart action. Controls secretion. Functions of Sympathetic System CHAPTER XIX COMMON SENSATIONS AND THE SPECIAL SENSES: TOUCH, TASTE, SMELL, HEARING, AND SIGHT Organs necessary for sensation. - A peripheral organ for the reception of an impression, a nerve for its conduction, and a centre in the brain for the perception, are the three essential parts of a sensory apparatus. It is by means of impressions received by the peripheral organs and conducted by the nerves to the brain that the mind is able to control the body and to take cognizance of the external world. CLASSIFICATION OF SENSATIONS Common sensations and special sensations. - These last are commonly called the special senses, and are touch, taste, smell, hearing, and sight. COMMON SENSATIONS Under this heading may be grouped a number of sensations often of a very indefinite character. They are the various ob- scure sensations proceeding from the viscera, which may give us the feeling of well-being or of the reverse. The sensations of hunger, of thirst, also of fatigue, and of satiety, belong to this class. Besides these, there are some sensations which involve certain organs which must be classed under this head; thus, incli- nations to cough or to sneeze or to vomit are common sensations, also to urinate or defecate. Pain. - The nerve-endings of the sense of pain are very widely distributed throughout almost the whole body, so that it is a common sensation. It is closely allied to that of touch, but the two may be differentiated. 336 Chap. XIX] ORGANS OF SPECIAL SENSE 337 Difference between common and special sensations. - The most important difference between common and special sensa- tions is that the former are strictly limited to the condition of our bodies, while by the latter we gain, in addition, information respecting affairs outside of our bodies. This difference may be explained if we compare the sensations of pain and touch, the one a common, the other a special, sensation. For example, if the point of a needle be gently pressed against the tip of the finger, we only feel this point by our sense of touch, and refer the sensation to the object causing it. But if the needle be pressed harder, so as to enter the skin, we feel at once a sensation of pain, which is no longer referred to the needle, but to the finger itself. The sensation of pain is not able to cause us to recognize the object which caused it, nor its nature. Sensations and perceptions. - Our habit of referring sensations to outside causes leads us to consider as properties of external bodies the sensations which they excite in us. When we speak of anything as having a bad taste, we forget that it only tastes bad to us. This habit pertains-especially to sensations of touch and sight. From constant exercise of it we finally come to believe implicitly in the "evidence of our senses." Judgments. - There is a distinction between a sensation and a judgment (which is often unconsciously based on sensations). When we estimate the distance of an object from ourselves, we form a judgment based on past experience of many sensations, such as the number of steps we must take before we touch it, etc. Nerves of special sense. - The special nerves have no other function than the special one for which they are set apart; and when they are separated from their special organs for receiving impressions, they no longer respond to the customary stimuli. TOUCH The special organs of the sense of touch (tactile corpuscles) are distributed over the entire surface of the body, being more or less numerous in all parts of the true skin and the adjoining mucous membrane. Touch is really only a specialized develop- ment of common sensation or sensibility. By means of the sense 338 ANATOMY FOR NURSES [Chap. XIX of touch we acquire knowledge of the size, figure, solidity, and other external peculiarities of bodies. Varieties of touch. - (1) Tactile sensibility, or touch proper; (2) the sense of pressure or weight; (3) the sense of temperature. If the nerves of the skin are unduly stimulated by severe pres- sure, or by exposure to extremes of heat or cold, the sense of touch and of temperature is lost in the sense of pain. This is also the case if the nerves are too freely exposed, as when the epidermis is removed by blistering, or in some other manner, and the skin is left "raw." Acuteness of touch. - The sensations produced by the stimu- lation of the touch endings in different parts of the body resemble each other, but are not identical, and the more numerous the tactile bodies, the more acute the sensibility of the part. Again, the thickness of the epidermis has marked influence in deter- mining the tactile ability. Calloused portions of the hands and feet have very blunted sensibility. The hand is of great value as an organ of touch because of the acuteness of its sensibility. Further than this, the hand is capable of forming impressions of bodies by reason of its power to grasp them and to test them as to weight. Pressure sensation. - When weight is added to an ordinary touch, the sensation of the pressure of the weight is felt, and by it one can judge with considerable accuracy the amount of the pressure, and determine the comparative pressure of two weights. This is known as the sense of pressure. Muscular sense. - The end organs of the muscular sense are situated in the tendons and between the fibres of the muscles. They convey to us the sense of resistance in the muscles when we attempt to lift anything. This is the muscular sense. Through it precision of effort is rendered possible; for by it we learn to adjust the force exerted to the weight of the object to be lifted. Thus the function of muscular sense is to enable us to estimate weight or resistance. It also aids in preserving equilibrium and in coordinating muscular action. Temperature. - In addition to the end organs of the sense of touch, there are also structures in the skin which are only stimulated by changes in temperature. These structures are of two kinds: stimulation of one causing the feeling of cold; Chap. XIX] ORGANS OF SPECIAL SENSE 339 stimulation of the other, the feeling of heat. These sensations are not accurate; they are only relative - that is, we infer from the temperature of the skin or of our habitual surroundings the warmth or coldness of the thing tested. TASTE Necessary conditions.-Aside from the conditions which are always necessary for sense-perception, - viz. proper organs for receiving, communicating, and perceiving the sensory impulse, - there must be present a sapid substance which must be in solu- tion. The solution in the case of dry substances is effected by saliva. It is also necessary that the surface of the organs of taste shall be moist. The substances which excite the special sensa- tion of "taste" act by producing a change in the terminal fila- ments of the gustatory nerve, and this change furnishes to it the required stimulant. Organs of taste. - The special organs of the sense of taste are on the surface of the tongue, though there are some of these organs scattered over the soft palate, fauces, tonsils, and pharynx. Tongue. - The tongue is a freely movable, muscular organ covered with epithelium. This epithelium closely resembles the skin in structure, except that the papillae it contains are more highly developed. The papillae project as minute prominences, and give the tongue its characteristic rough appearance. Some of the papillae are simple, and resemble those found in the skin; the remainder are compound,1 and are only found on the surface of the tongue. Of these compound papillae there are three varieties: - (1) Circumvallate (walled in) papillae are the largest, and are .about eight or ten in number, and form a V-shaped row near the root of the tongue, with its open angle turned towards the lips. (2) Fungiform papillae 2 are the next in size, and are found principally on the tip and sides of the tongue. 1 A compound papilla is one large one bearing several smaller ones on its surface. 2 The fungiform papillae resemble fungi, having an expanded upper por- tion resting on a short, thick pedicle. The circumvallate papillae resemble the fungiform, except that they are surrounded by a wall of smaller papillae. 340 ANATOMY FOR NURSES [Chap. XIX (3) Filiform papilla? are the smallest and most numerous. They are found all over the tongue, except at the root, and bear on their free surface a form of ciliated epithelium. In some animals the hair-like processes on the filiform papillae are horny in structure, and their tongues are correspondingly roughened, Fig. 197.-The Upper Surface of the Tongue. 1, 2, circumvallate papillae; 3, fungiform papillae; 4, filiform papillae; 6, mucous glands. (Sappey.) so that they supplement the teeth in the bruising and crushing of food. In man these hair-like processes are exceedingly delicate, and seem to be specially connected with the sense of touch, which on the tip of the tongue is highly developed, and which serves to guide the tongue in its variable and complicated move- ments. Chap. XIX] ORGANS OF SPECIAL SENSE 341 In the circumvallate, some of the fungiform papillae, and scat- tered also over the epithelium of the tongue and soft palate, are little clusters of cells lying in cavities of the epithelium, called taste-buds. The taste-buds are the essential end organs in which the sense of taste arises. The bases of these cell-clusters, or taste-buds, are supplied with nerve-fibres. The nerve-fibres are derived from the glossopharyngeal and from the chorda tympani, a branch of the facial. The former supplies the back of the tongue, and section of it destroys taste in that region; the latter is distributed to the front of the tongue, and section of it, similarly, deprives the tip of the tongue of taste. Other sensations in the tongue. - The sense of touch is very highly developed here, and with it the sense of temperature, pres- sure, pain, etc.; upon these tactile and muscular senses to a great extent depend the accuracy of the tongue in many of its impor- tant uses - speech, mastication, deglutition, sucking. We often confound taste with smell. Substances which have a strong odour, such as onions, are smelled as we hold them in our mouths; and if our sense of smell is temporarily suspended, as it sometimes is by a bad cold in the head, we may eat garlic and onions and not taste them. Hence the philosophy of holding the nose when we wish to swallow a nauseous dose. SMELL Necessary conditions. - The first essentials are a special nerve and nerve centre, the changes in whose condition are perceived as sensations of odour. No other nerve structure is capable of such sensations, even when acted on by the same cause. The special organs for this sense must be in their normal condition, and a stimulus (odour) must be present to excite them. Odours are caused either by minute particles of solid matter or by gases which are in the atmosphere, and they must be capable of solution in the mucus of the pituitary membrane. Odorous particles in the air, passing through the lower, wider air-passages, pass by diffusion into the higher, narrower, nasal chambers, and falling on the membrane which is provided with olfactory nerve-endings, produce sensory impulses, which, ascending to the brain, give rise to the sensations of smell. 342 ANATOMY FOR NURSES [Chap. XIX If we wish to smell anything particularly well, we sniff the air up into the higher nasal chambers, and thus bring the odorous particles more closely into contact with the olfactory nerves. Each substance we smell causes its own particular sensation, and we are not only able to recognize a multitude of distinct odours, but also to distinguish individual odours in a mixed smell. The sensation takes some time to develop after the contact of the odorous stimulus, and may last a long time. When the stim- ulus is repeated, the sensation very soon dies out, the sensory terminal organs quickly becoming exhausted.1 The nose. -The nose is the special organ of the sense of smell- It consists of two parts, - the external feature, the nose, and the internal cavities, the nasal fossae. The external nose is com- posed of a triangular frame- work of bone and cartilage, covered by skin and lined by mucous membrane. On its under surface are two oval- shaped openings - the nostrils - separated by a partition. The margins of the nostrils are provided with a number of stiff hairs which arrest the passage of dust and other foreign sub- stances carried in with the inspired air. The nasal fossse are two irregularly wedge-shaped cavi- ties, separated from one an- other by a partition, or sep- tum, and communicating with the air in front by the anterior nares, or nostrils, while behind they open into the back of the pharynx by the two posterior nares. Eleven bones enter into Fig. 198.-Vertical Longitudi- nal Section of Nasal Cavity. 1, olfactory nerve; v, branch of fifth nerve; h, hard palate. 1 This accounts for the fact that one may easily become accustomed to foul odours, and is of special importance to nurses. Foul odours are quickly noticed by any one coming into a sick room from out of doors, but a nurse who is in the sick room constantly may become accustomed to such odours. Hence the importance of acting on the first sensation of a disagreeable odour. Chap. XIX] ORGANS OF SPECIAL SENSE 343 the formation of the nasal cavities: the floor is formed by the palate (2) and part of the maxillae bones (2); the roof is chiefly formed by the perforated (cribriform) plate of the ethmoid bone (1), the sphenoid (1) and by the (2) small nasal bones; in the outer walls we find, in addition to processes from other bones, the two scroll-like turbinated bones (2). The turbinated bones and turbinated processes of the ethmoid, which are ex- ceedingly light and spongy, project into the nasal cavities, and divide them into three incomplete passages from before back- wards, - the superior, middle, and inferior meatus. The vomer (1) separates the two nasal cavities. The palate and maxillae separate the nasal and mouth cavities, and the crib- riform plate of the ethmoid forms the partition between the cranial and nasal cavities. (See Fig. 155.) In addition to the bony structure of the nose at least two- thirds of the facial portion and one-third of the septum have a framework of cartilage. The pituitary membrane (sometimes called the Schneiderian membrane) is the mucous lining of the nose. It closely covers the nasal passages, and is thickest and most vascular over the turbinated bones. In some nasal troubles it becomes much thickened and swollen, and occludes the nasal passages to such an extent as to compel us to breathe through the mouth. It contains numerous mucous glands which secrete mucus for the purpose of keeping the membrane moist, - a condition which is essential to perfection of the sense of smell. Olfactory nerves. - The olfactory nerves are the special nerves of the sense of smell, and are spread out in a fine network over the surface of the superior turbinated processes of the ethmoid bone and on the upper third of the septum. The nerves end in special organs known as olfactory cells, which lie under the epithelium, but send prolongations between the mucous cells to the surface. The central portion of the olfactory cells are pro- longed as nerve-fibres into a mass of gray matter, called the olfactory bulb, which rests upon the cribriform plate of the eth- moid bone. The nerves which ramify over the lower part of the lining mem- brane of the nasal cavity are branches of the fifth or trigeminal nerve. These nerves furnish the tactile sense and enable us to 344 ANATOMY FOR NURSES [Chap. XIX perceive, by the nose, the sensations of cold, heat, tickling, pain, and tension or pressure. HEARING The auditory apparatus consists of (1) the external ear; (2) the middle ear; (3) the internal ear; and (4) the auditory nerve. External ear. - The external ear consists of an expanded por- tion named pinna, or auricle, and the auditory canal, or meatus. The auricle is composed of a thin plate of yellow fibro-cartilage, covered with skin, and joined to the surrounding parts by liga- ments and a few muscular fibres. It is very irregular in shape, Fig. 199.--Semi-diagrammatic Section through the Right Ear. M, concha; G, the external auditory canal; T, tympanic, or drum-membrane; P, tympanum, or middle ear; o, oval window; r, round window. Extending from T to o is seen the chain of the tympanic bones; R, Eustachian tube; V, B, S, bony labyrinth; V, vestibule; B, semicircular canal; S, cochlea; b, I, v, membranous labyrinth in semicircular canal and in vestibule. A, auditory nerve dividing into branches for vestibule, semicircular canal, and cochlea. and appears to be an unnecessary appendage to the organ of hearing, except that the central depression, the concha, serves to some extent to collect sound-waves, and to conduct them into the auditory canal. The auditory canal is a tubular passage, about an inch (25 mm.) in length, leading from the concha to the drum-membrane. It is slightly curved upon itself, so as to be higher in the middle Chap. XIX] ORGANS OF SPECIAL SENSE 345 than at either end. It is lined by a prolongation of the skin, which in the outer half of the canal is veiy thick and not at all sensitive, and in the inner half is thin and highly sensitive. Near the orifice the skin is furnished with a few hairs, and far- ther inwards with modified sweat-glands, the ceruminous glands, which secrete a yellow, pasty substance resembling wax. This wax is thought to be offensive to insects, and consequently a defence against their intrusion. Middle ear.-The middle ear, or tympanum, is a small, ir- regularly flattened cavity, situated in the petrous portion of the temporal bone, and lined with mucous membrane. It is sepa- rated from the external auditory canal by the drum-membrane Fig. 200. - Ossicles of the Tympanum, X 4. I, ossicles of the left ear; 1, malleus; 2, incus; 3, stapes. II, ossicles of the right ear; 1, malleus; 2, long process; 3, handle; 4, long process of the incus; 5, short process of the incus; 6, stapes. (Flint.) (membrana tympani), and from the internal ear by a bony wall in which there are two small openings covered with membrane - the oval window, or fenestra ovalis, and the round window, or fenestra rotunda. The cavity of the middle ear is so small that probably five or six drops of water would completely fill it. It communicates below with the pharynx by the small passage called the Eustachian tube,1 through which air enters the cavity 1 This direct connection between the ear and the pharynx is one of the important reasons for the frequent cleansing of the mouth necessary in in- fectious and contagious diseases. The Eustachian tube forms a passageway for germs to travel from the mouth to the middle ear and there cause various infections. 346 ANATOMY FOR NURSES [Chap. XIX and serves to keep the atmospheric pressure equal on each side of the drum-membrane. The middle ear also communicates above with a number of bony cavities in the mastoid portion of the temporal bone. These cavities, called mastoid cells, are lined with mucous membrane, which is continuous with that covering the cavity of the tympanum. Membrana tympani (membrane of the drum). It is a tough, fibrous membrane set in the bony opening of the external audi- tory canal. The degree of tension of the membrane is regulated by the tensor tympani muscle. This muscle is lodged in a bony canal that is above and parallel with the Eustachian tube. Ossicles. - Stretching across the tympanic cavity is a chain of tiny movable bones, three in number, and named from their shape the malleus, or hammer, the incus, or anvil, and the stapes, or stirrup. The malleus is firmly attached to the drum-mem- brane, and the stapes is fastened into the oval window (also covered by membrane) leading into the inner ear. The incus is placed between the malleus and stapes, and attached to both by delicate articulations. These little bones are set in motion with every movement of the drum-membrane. Vibrations of the mem- brane are communicated to the malleus, taken up by the incus, and transmitted to the stapes, which rocks in the fenestra ova- lis, and is therefore capable of transmitting to the fluid in the cavity of the labyrinth the impulses which it receives. Internal ear. - The internal ear, or labyrinth, receives the ulti- mate terminations of the auditory nerve, and is, therefore, the essential part of the organ of hearing. It consists of a bony labyrinth, which is composed of a series of peculiarly shaped cavities, hollowed out of the petrous portion of the temporal bone, and named from their shape: - (a) The vestibule. (6) The semicircular canals. z (c) The cochlea (snail-shell). This bony labyrinth is lined by a serous membrane, which se- cretes a watery fluid called the perilymph. Membranous labyrinth. - Lying within the bony labyrinth and perilymph is a membranous labyrinth, which is composed of a series of sacs, or tubes, fitting more or less closely within the vestibule, semicircular canals, and cochlea. Chap. XIX] ORGANS OF SPECIAL SENSE 347 The membranous labyrinth is filled with a watery fluid called endolymph. In its walls terminate the final ramifications of the auditory nerve. Before its termination, the auditory nerve divides into two branches, the cochlear supplying the cochlea, the vestibular supplying the vestibule and semicircular canals. The cells of origin of these two branches constitute two ganglia situated in the region of the labyrinth. Their dendrites are dis- Fig. 201.-The Left Bony Labyrinth of a New-born Child, Forward and Outward View, X 4. From a photograph, and slightly reduced. 1, the wide canal, the beginning of the spiral canal of the cochlea; 2, the fenestra rotunda; 3, the second turn of the cochlea; 4, the final half-turn of the cochlea; 5, the border of the bony wall of the vestibule, situated between the cochlea and the semicircular canals ; 6, the superior, or sagittal semicircular canal; 7, the portion of the semicircular canal bent outward; 8, the posterior, or trans- verse semicircular canal; 9, the portion of the posterior connected with the supe- rior semicircular canal; 10, point of junction of the superior and the posterior semicircular canals; 11, the ampulla ossea externa; 12, the horizontal, or external semicircular canal. (Flint.) tributed to the epithelial lining of the membranous sac, while the axis cylinders form the trunk of the auditory nerve and pass back to the medulla oblongata. That portion of the membranous labyrinth that is lodged in the bony cochlea is triangular in shape on cross-section, although it is spirally twisted to follow the general shape of the cochlea, and is known as the canalis cochlearis, or scala media. Lodged on the membrane (membrana basilaris), forming the base of this tri- angular canal, is the organ of Corti. Organ of Corti. - It consists of a series of special nerve organs placed in a row. It is supposed that each end organ responds 348 ANATOMY FOR NURSES [Chap. XIX to a given, number of vibrations, thus covering all the range of sound. These end organs are continuous with the fibres of the eighth, or auditory nerve, which carries the sensations of hearing back to the medulla. All bodies which produce sound are in a state of vibration, and communicate their vibrations to the air with which they are in contact, and thus the air is thrown into waves, just as a stick waved backwards and forwards in water throws the water into waves. When air-waves, set in motion by sonorous bodies, enter the external auditory canal, they set the drum-membrane vibrating, stretched membranes taking up vibrations from the air with great readiness. These vibrations are communicated to the chain of tiny bones stretched across the middle ear, and their oscilla- tions cause the membrane leading into the internal ear to be alternatively pushed in and drawn out, and vibrations are in this way transmitted to the perilymph. Each vibration communi- cated to the perilymph travels as a wave over the vestibule, semicircular canals, and cochlea, and is transmitted through the membraneous walls to the endolymph. The vibrations of the endolymph stimulate the nerve-endings of the organ of Corti, and nervous impulses are conveyed by the auditory nerve to those parts of the brain, stimulation of which gives rise to the sensation of sound. The effect produced by a sonorous vibration continues for a short time after the cessation of its cause. Usually the interval between two different impulses is sufficient to allow the first impression to disappear before the second is received, and the ear distinguishes them in succession. But if they follow each other at equal intervals, with a certain rapidity, they produce the impression of a continuous sound; and this sound has a higher or lower pitch according to the rapidity of its vibrations. It has been discovered that sound-waves following each other with a rapidity of less than sixteen times per second are separately distinguishable; but above that frequency they are merged into a continuous sensation. When the sound-waves recur at irregular intervals, the only characters perceptible in the sound are its intensity and quality. But if they succeed each other at regular intervals, the sound produced has a position in the musical Chap. XIX] ORGANS OF SPECIAL SENSE 349 scale as a high or low note. The more frequent the repetitions, the higher the note; but a limit is at last reached, at which the ear fails to perceive the sound, and an excessively high note is therefore inaudible. Sonorous vibrations, perceptible to man as musical notes, range between sixteen per second for the lowest notes and 38,000 for the highest. (Dalton.) The sense of equilibrium. - Among the various means (such as sight, touch, muscular sense) whereby we are enabled to main- tain our equilibrium, coordinate our movements, and become aware of our position in space, one of the most important is the action of the vestibule and semicircular canals. The vestibule consists practically of a sac, from the walls of which pro- ject sensory hairs, in relation at their bases with dendrites of the vestibular nerve. Among these hairs rest sev- eral small calcareous bodies called otoliths. Each semicircular canal consists of a curved tube enlarged at one end (ampulla). In this ampulla are hairs around which the dendrites of the vestibular nerve terminate. The hairs in the ampullae are stimulated by the flowing of the endolymph, and the canals are so arranged (Fig. 202) that any movement of the head causes an increase in the pressure of the endolymph in one ampulla, and a corresponding diminution in the ampulla of the parallel canal on the opposite side. Thus, a nodding of the head to the right would cause a flow of the endo- lymph from a to b in the right anterior vertical canal, but from b' to a' in the left posterior vertical canal. Hence the pressure upon the hairs is decreased in a, but increased in a'. Such stimu- lations of the sensory hairs are transmitted by the dendrites of the vestibular nerve, through the cell-bodies of the vestibular ganglion and the axis cylinders of the auditory nerve, to the brain, and it is the function of the semicircular canals to give us a knowledge of the position of the head when at rest. The intensity and direction of the pressure of the otoliths upon the Fig. 202.-Diagram show- ing Relative Position of the Planes in which the Semi- circular Canals lie. Rt., right ear; Lt., left ear; A.V., anterior vertical canal; P.V., posterior vertical canal; H., horizontal canalj a, ampulla of Rt. anterior vertical canal; a', ampulla of Lt. posterior vertical canal. 350 ANATOMY FOR NURSES [Chap. XIX sensory hairs of the vestibule are also thought to give us a like knowledge; namely, the position of the head when at rest. SIGHT The visual apparatus is the eye, with its accessory organs and the optic nerve. Accessory organs of the eye. - Under this heading we class (1) eyebrows, (2) eyelids, (3) lacrimal apparatus, (4) muscles of the eyeball. Eyebrows. - The eyebrows are composed of two arched emi- nences of thickened skin, connected with three muscles, which by their action control to a limited extent the amount of light admitted into the eye. The eyebrows are furnished with numer- ous short, thick hairs, lying obliquely on the surface. Eyelids. --• The eyelids are two folds projecting from above and below in front of the eye. They are covered externally by the skin, and internally by a mucous membrane, the conjunctiva, which is reflected from them over the globe of the eye. They are composed for the most part of connective tissue, which is dense and fibrous under the conjunctiva, where it is known as the tarsus. Arranged in a double or triple row at the margin of the lids are the eyelashes; those of the upper lid, more numerous and longer than the lower, curve upwards; those of the lower lid curve downwards, so that they do not interlace in closing the fids. The upper lid is attached to a small muscle which is called the elevator of the upper lid (levator palpebrae superioris), and arranged as a sphincter around both lids is the orbicularis pal- pebrarum muscle, which closes the eyelids, and is the direct antagonist of the elevator of the upper lid. The slit between the edges of the lids is called the palpebral fissure. It is the size of this fissure which causes the appearance of large and small eyes, as the size of the lobe itself varies but little. The outer angle of this fissure is called the external canthus. The inner angle, the internal canthus. The eyelids are obviously provided for the protection of the eye; movable shades which by their closure exclude light, par- ticles of dust, and other injurious substances. Chap. XIX] ORGANS OF SPECIAL SENSE 351 Tarsal glands (Meibomian glands). - Embedded in the tarsus of each eyelid is a row of elongated sebaceous glands, - the tar- sal 1 glands, - the ducts of which open on the edge of the eye- lid. The secretion of these glands is provided to prevent adhesion of the eyelids. Lacrimal apparatus. - This apparatus consists of (1) the lac- rimal gland, (2) canaliculi, (3) lacrimal sac, and (4) nasal duct. The lacrimal gland is a compound gland, close- ly resembling the sali- vary glands in structure, and is lodged in a de- pression at the upper and outer angle of the orbit. It consists of two portions, an upper por- tion about the size and shape of an almond, and a lower portion consist- ing of a group of small glands arranged in a row. These two portions are only partially separated by a fibrous septum. Seven to twelve mi- nute ducts lead from the gland to the surface of the conjunctiva of the upper lid. The secretion (tears) is usually just enough to keep the eye moist, and after passing over the surface of the eyeball is sucked into two tiny canaliculi through the punctae and is conveyed into the lacrimal sac, which is the upper dilated portion of the nasal duct. The nasal duct is a membranous canal, about three-quarters of an inch (19 mm.) in length, which extends from the lacrimal sac to the inferior meatus of the nose, into which it opens by a slightly expanded orifice. The tears consist of water containing a little salt and albumin. They are ordinarily carried away as fast as formed, but under Fig. 203. - The Lacrimal Apparatus. (Note that preference is given to the spelling " lacrimal " as found in text, instead of " lachry- mal" as found on illustration.) 1 By everting the eyelids, these glands may be seen through the conjunc- tiva lying in parallel rows. 352 ANATOMY FOR NURSES [Chap. XIX certain circumstances, as when the conjunctiva is irritated, or when painful emotions arise in the mind, the secretion of the lacrimal gland exceeds the drainage power of the nasal duct, and the fluid, accumulating between the lids, at length overflows and runs down the cheeks. Muscles of the eye. - The muscles which move the eye are four straight, or recti, and the two oblique. They have been described in Chapter VI. Nerves of the eye. - The optic nerve and the nerves of the muscles of the eye are described in Chapter XVIII. Eyeball. - The eyeball is contained in a bony cavity, the orbit. Seven bones assist in the formation of each orbit, namely, frontal, malar, maxilla, palate, ethmoid, sphenoid, and lacrimal. As three of these bones are mesial (frontal, ethmoid, and sphenoid) there are only eleven bones forming both orbits. Each orbit averages from 1| inches (44 mm.) to 2 inches (50 mm.) in depth, is padded with fat and lined with a membra- -CILIARY PROCESSES -SUSPENSORY LIGAMENT - OPTIC NERVE VITREOUS HUMOR - SUSPENSORY LIGAMENT -CILIARY PROCESSES Fig. 204.--Diagrammatic Section of the Eye. (Flint.) nous capsule, - the capsule of Tenon. This capsule is a serous sac, one layer of which is attached to the posterior portion of the eyeball, while the other lines the orbital cavity; in this way the eyeball is isolated from surrounding structures, and free move- ment without friction is insured. The orbit is shaped like a four- sided pyramid; the apex, directed backwards and inwards, is Chap. XIX] ORGANS OF SPECIAL SENSE 353 pierced by a large opening - the optic foramen - through which passes the optic nerve. A larger opening to the outer side of the optic foramen -the sphenoidal fissure-transmits the nerves and blood-vessels distributed to the eyeball. The base of the orbit, directed outwards and forwards, forms a strong, bony edge for protecting the eyeball from injury. The eyeball is spherical in shape, but its transverse diameter is less than the antero-posterior, so that it projects anteriorly, and looks as if a section of a smaller sphere had been engrafted on the front of it. Dimensions of the eyeball: - Transverse 1. inch (25 mm.) Vertical 96 inch (24 mm.) Antero-posterior 96 inch (24 mm.) Optic nerve and sheath ... .16 inch ( 4 mm.) Lens - antero-posterior . . . .19 inch ( 4.75 mm.) Lens - transverse 35 inch ( 8.75 mm.) Pupil (average) 14 inch ( 3.5 mm.) The eyeball is composed of three coats, or tunics, and contains three refracting media or humours. They are as follows: - Tunics.- 1. Sclera and cornea. 2. Choroid, ciliary processes, and iris. 3. Retina. Refracting media. - 1. Aqueous. 2. Crystalline lens and capsule. 3. Vitreous. Sclera. - The sclera (derived from the Greek word signifying hard) covers the posterior five-sixths of the eyeball. It is com- posed of a firm, unyielding, fibrous membrane, thicker behind than in front, and serves to protect the delicate structures con- tained within it. It is opaque, white, and smooth externally, and behind is pierced by the optic nerve. Internally it is stained brown where it comes in contact with the choroid coat. It is supplied with very few blood-vessels, and the existence of nerves in it is doubtful. Cornea. - The cornea (derived from Latin cornu, horn, and therefore also signifying hard) covers the anterior sixth of the eyeball. It is directly continuous with the sclera, which, how- 354 ANATOMY FOR NURSES [Chap. XIX ever, overlaps it slightly above and below, as a watch crystal is overlapped by the case into which it is fitted. The cornea, like the sclera, is composed of fibrous tissue, which is both firm and unyielding, but, unlike the sclera, it has no colour, and is per- fectly transparent: it has been aptly termed the "window of the eye." Both the cornea and the anterior portion of the sclera are covered by reflections of the mucous membrane lining the eyelids. This is called the conjunctiva, and, kept well lubricated by the secretions of the eye, gives the eyeball its peculiar shining and glossy aspect. The cor- nea is well supplied with nerves and lymphatics, but is destitute of blood-vessels. Choroid. - The choroid, or vascular coat of the eye, is a thin, dark brown membrane lining the inner surface of the sclera. It is composed of flimsy, gauzy connective tis- sue, the cells of which are large and filled with pigment, and it contains a close net- work of blood-vessels. It extends to within a short distance of the cornea. Ciliary processes. -- The ciliary processes are continu- ations of the choroid behind and connect with the iris in front. Just behind the edge of the cornea the choroid is folded inwards and arranged in radiating folds, like a plaited ruffle, around the lens. There are about seventy of these folds, and they constitute the ciliary processes. They are well supplied with nerves and blood- vessels, and also support a muscle, the ciliary muscle. The fibres of this muscle arise from the sclera near the cornea, and extending backward are inserted into the outer surface of the ciliary pro- RADIATING VESSELS OF IRIS CILIARY PROCESS Fig. 205. - Segment of the Iris, Ciliary Body, and Choroid. Viewed from the internal surface. (Gerrish.) Chap. XIX] ORGANS OF SPECIAL SENSE 355 cesses and the choroid. The action of this muscle determines the position of the lens. Iris. - The iris (iris, rainbow) is a coloured, fibro-muscular curtain hanging in front of the lens and behind the cornea. It is attached at its circumference to the ciliary processes, with which it is practically continuous, and is also connected to the sclera and cornea at the point where they join one another. Except for this attachment at its circumference, it hangs free in the interior of the eyeball. In the middle of the iris is a cir- cular hole - the pupil - through which light is admitted into the eye chamber. The iris, like the choroid, is composed of con- nective tissue contain- ing a large number of pigment cells and nu- merous blood-vessels. It contains, in addi- tion, two sets of plain muscular fibres. One set forms a flat band round the margin of the pupil, and is called the sphincter, or con- tractor of the pupil; the other set consists of radiating fibres converging from the circumference to the centre, and is called the dilator of the pupil. The action of these muscle-fibres is affected by light. Under the influence of a bright light the pupil involuntarily contracts, so that less light is admitted into the eye chamber; in a dim light the pupil involuntarily dilates to admit as much light as possible. The posterior surface of the iris is covered by a. thick layer of pigment-cells designed to darken the curtain and prevent the entrance of light. The anterior surface of the iris is also covered with pigment cells, and it is chiefly these latter which cause the beautiful colours Fig. 206. - Choroid Membrane and Iris EXPOSED BY THE REMOVAL OF THE SCLERA AND Cornea. Twice the natural size, d, one of the segments of the sclera thrown back; Zand k, iris; c, ciliary nerves; e, one of the veins of the choroid. The ciliary muscle is crossed by the line from k, and should be represented as radiating. (Collins.) 356 ANATOMY FOR NURSES [Chap. XIX seen in the iris. The different colours of eyes, however, are mainly due to the amount, and not to the colour, of the pigment deposited. Retina. - The retina, the innermost coat of the eyeball, is the most essential part of the organ of sight, since it is the only one directly sensitive to light. The sclera is the protective, the choroid the vascular, or nutritive, and the retina is the visual, or perceptive, layer of the eye- ball. It forms a transpar- ent membrane of a grayish colour situated between the inner surface of the choroid and the outer surface of the vitreous humour, and ex- tending from the exit of the optic nerve to the com- mencement of the ciliary processes. The retina is usually described as consisting of eight layers and two limit- ing membranes; of these layers, three are most im- portant : - (1) Eighth layer, or layer of nerve-fibres, is the inter- nal layer. (2) Seventh layer is the layer of nerve-cells. (3) First layer, or layer of rods and cones, is the external layer. (See Summary, page 366.) The fibres of the optic nerve, after piercing the sclera and choroid at the back of the eye, spread out and form the eighth, or innermost, layer of the retina. The fibres then pass, with more or less direct communications, peripherally through the Fig. 207. - Diagrammatic Section of the Human Retina. 8, layer of nerve- fibres; 7, layer of nerve-cells; 1, layer of rods and cones. (M. Schultze.) Chap. XIX] ORGANS OF SPECIAL SENSE 357 other layers, until they may be said to terminate in the layer of rods and cones. Rays of light produce no effect upon the optic nerve without the intervention of the rods and cones. Blind spot. - The optic nerve pierces the eyeball not exactly at its most posterior point, but a little to the inner side. This point where the optic nerve enters is called the blind spot. There are no rods and cones at this spot, and rays of light falling upon it produce no sensation. Macula lutea. - There is one point of the retina that is of great importance, and that is the macula lutea, or yellow spot. It is situated about one-twelfth inch (2.08 mm.) to the outer side of the exit of the optic nerve, and is the exact centre of the retina. In its centre is a tiny pit, - fovea centralis, - which is the centre of direct vision; that is, it is the part of the retina which is always turned towards the object looked at. From this point the sensitiveness of the retina grows less and less in all directions. At this point (fovea centralis) are found none of the fibres of the optic nerve, but a great increase in the number of cones, as well as in their size. Light may be described as consisting of vibrations in the ether which pervades space. These ethereal vibrations enter the eye through the cornea, pass in through the pupil and refracting media, and strike on the retina. They penetrate the transparent retina until they fall upon the rod and cone cells. In these there occur certain substances which are acted upon by the light (much as the film of a photographic plate is acted upon by the light). The chemical changes which these substances undergo stimulate the adjacent dendrites, and the impulse passes through the cell- Fig. 208.-The Posterior Half of the Retina of the Left Eye viewed from Before. Twice its natural size, s, cut edge of the sclera; ch, choroid; r, retina; in the interior at the middle, the macula lutea with the depression of the fovea centralis is represented by a slight oval shade; toward the left side the light spot indicates the entrance of the optic nerve or blind spot. (Collins.) 358 ANATOMY FOR NURSES [Chap. XIX bodies and the axis cylinders to the second series of neurones, and then through their dendrites and cell-bodies to their axis cylin- ders. These last converge toward the blind spot, where they unite to form the optic nerve, which, passing from the eye to the brain, conducts the sensory impulses derived from the chemi- cal changes occurring in the rods and cones to the visual centre, and the perception of light is produced. As in the case of the end organs of touch each had its local sign, so each rod and cone has its own particular local sign, but this local sign is not associated in our minds with the part of the retina stimulated, as we associate touch with a certain portion of the skin stimulated. In the case of the retina, the local sign is associated with the source of the light, which acts as the stimu- lus. Thus, when the upper part of the retina is stimulated, we know that the source of light, the object which we see, is below the line of direct vision; and when the lower, the right, or the left-hand portion of the retina is stimulated, we know that the object lies above the line of direct vision, or to the left or right of it, as the case may be. From this it will be seen that the image projected on the retina is an inverted image, but the perception centres in the brain correct this inversion, so that the impression of the object seen is in true relationship with the object itself. Aqueous humour. - The space bounded by the cornea in front and by the lens, suspensory ligament, and ciliary body be- hind is filled with a colourless, transparent, watery fluid, the aqueous humour. This space is known as the aqueous chamber, and is partially divided by the iris into an anterior and posterior chamber. Vitreous humour. - The posterior four-fifths of the globe of the eyeball is filled with a semi-fluid, gelatinous substance, the vit- reous humour, or body, so called from its glassy and transparent appearance. It is enclosed in a thin membrane - the hyaloid membrane. This membrane is attached to the retina at the back of the eyeball, and furnishes a suspensory ligament to the lens. Elsewhere it is perfectly separable from its surroundings. The vitreous humour enclosed in this capsule distends the greater part of the sclera, supports the retina, which lies upon its surface, and preserves the spheroidal shape of the eyeball. Its refractive Chap. XIX] ORGANS OF SPECIAL SENSE 359 power, though slightly greater than that of the aqueous humour, does not differ much from that of water. Crystalline lens. - The crystalline lens is a transparent, refrac- tive body, with convex anterior and posterior surfaces, placed directly behind the pupil, where it is retained in position by the counterbalancing pressure of the aqueous humour and vitreous body, and by its own suspensory ligament described above. The posterior surface is considerably more curved than the an- terior, and the curvature of each varies with the period of life. In infancy, the lens is almost spherical; in the adult, of medium convexity; and in the aged, considerably flattened. It is a fibrous body, enclosed in an elastic, non-vascular capsule. Just beneath the capsule the substance is soft and gelatinous, but deeper it becomes hard and firm. Its refractive power is much greater than that of the aqueous or vitreous humour, and it acts by virtue of its double-convex form as a con- verging lens, bringing parallel or diverging rays to a focus on the posterior surface of the retina. Function of the lens. - The function of the crystalline lens is to bring to a focus all the rays of light emanating from each separate point in the object seen, so that all the light from each point falls on and stimulates a correspond- ing point on the retina. For if the eye consisted only of a sensitive retina, impressions of light could be received, but the form of objects would not be distinguished. The action of the lens in thus focussing the rays of light at a particular point may be illustrated in the following manner. If a sheet of white paper be held at a short distance from a candle- flame, in a room with no other light, the whole of the paper will Fig. 209. - Diagram illustrating Rays of Light converging in a Nor- mal Eye, (A), a Myopic Eye, (B), and a Hypermetropic Eye, (C). 360 ANATOMY FOR NURSES [Chap. XIX be moderately and uniformly illuminated by the diverging rays. But if a double-convex lens, with suitable curvatures, be inter- posed between the paper and the light, the outer portions of the paper will become darker, and its central portion brighter, because a portion of the rays are diverted from their original course and bent inward. By varying the distance of the lens from the paper, a point will at last be found where none of the light reaches the external parts of the sheet, but all of it is con- centrated upon a single spot; and at this spot will be. seen a dis- tinct image of the candle and its flame, i.e. each point of the flame is now represented by a single point on the paper; and if for the paper we were to substitute the retina, each point would stimu- late one, and only one, small area of the retina. Perception of the figure of external objects therefore depends on the action of the crystalline lens in converging all the rays emanating from a given point to a focus on the retina. When the lens of the eye is too convex, and its refractive power excessive, the rays of light converge too soon and cross one another before reaching the retina; consequently, the image produced is not concentrated and distinct, but, dispersed more or less over the surface of the retina, is diffused and dim. On the other hand, if the lens is too flat, the rays do not converge soon enough, and the image is again diffused and indistinct. To remedy a too great convexity of the lens in the short-sighted, or myopic eye, concave spectacles are used to disperse the rays; to remedy the flattened lens in the hypermetropic, or long-sighted eye, we employ convex glasses to concentrate and focus the rays more quickly. Cataract. - Cataract is a fatty degeneration of the lens which makes it opaque and gives it a milky appearance. The only remedy is to remove the lens. The use of a convex lens of glass in front of the eye acts as a fair substitute, and in many instances gives a very good degree of vision. White spots on the cornea are the result of ulcers, and are often mistaken for cataracts. A normal eye is capable of distinct vision throughout an im- mense range. We can see the stars millions of miles away, and with the same eye, though not at the same time, we can see ob- jects within a few inches of us. To be able to see objects mill- ions of miles away and within a short range, the eye has to accommodate or adjust itself to different distances. This accom- modation is accomplished mainly by the lens changing its con- vexity. In accommodation for near objects, the lens becomes Chap. XIX] ORGANS OF SPECIAL SENSE 361 more convex (advances), and the pupil of the eye likewise con- tracts. This convexity is brought about by the action of the ciliary muscle, and is always more or less fatiguing. The ac- commodation for distant objects is a passive condition, the convexity of the lens being unaltered and the pupil of the eye dilated, and it is on this account that the eye rests for an indefi- nite time upon remote objects without fatigue. SUMMARY Organs Necessary for Sensation End organ for the reception of an impression. A nerve for conduction of an impression. । A centre in the brain for* perception. 1. Common sensations (strictly limited to the condition of our bodies) Hunger. Thirst. Fatigue. Satiety. Pain. Classification of Sensations Touch. Taste. Smell. Hearing. Sight. 2. Special sensations (we gain information regarding condition of our bodies and of outside affairs). Tactile corpuscles are end organs of sense of touch. Distributed over entire surface of body. 1. Tactile sensibility. 2. Sense of pressure, or weight. 3. Sense of temperature. Touch. . . Varieties Acuteness of touch depends upon ( 1. Number of tactile corpuscles. [ 2. Thickness of skin. Sensory apparatus 1. Taste-buds are end organs. 2. Nerve-fibres of glossopharyngeal nerve. 3. Centre in brain. Taste . . . Solution of sapid substances must come in contact with taste- buds. Surface of tongue. Soft palate and fauces. Tonsils and pharynx. Taste-buds are distributed over 362 ANATOMY FOR NURSES [Chap. XIX Freely movable muscular organ. Surface covered by papillae Simple. Compound. Tongue 1. Taste 2. Touch 3. Temperature 4. Pressure 5. Pain Sense of Are all well developed. Circumvallate are V-shaped row near root of tongue. Fungiform are found on tip and sides of tongue. Filiform are found all over tongue except root. Compound Papillae Sensory apparatus Olfactory nerve-endings. Olfactory nerve-fibres. Centre in brain. 'Minute particles of solid matter Gases Must be capable of solu- tion in mucus. Smell . . Odours Olfactory nerve-ending found in lining upper part of nose (smell). Branches of trigeminal nerve found in lining of lower* part of nose (touch). External nose ' Framework of bone (nasal) and cartilage. Covered with skin, lined with mucous mem- brane known as pituitary, or Schneiderian. Nostrils are oval-shaped openings on under sur- , face, separated by a partition. Extend from nostrils to the pharynx. Two wedge-shaped cavities. 2 palate. 2 maxillae. 1 ethmoid. 1 sphenoid. 2 nasal. Nose . . Internal cavities, or nasal fossae Formed by 2 turbinated and pro- cesses of the eth- moid Superior meatus. Middle meatus. Inferior meatus. 1 vomer. 11 bones. Chap. XIX] ORGANS OF SPECIAL SENSE 363 External ear. Middle ear. Internal ear. Auditory nerve. Centre in brain. Auditory apparatus Hearing Air-waves enter external auditory canal and cause vibra- tions of drum-membrane. The vibrations are conveyed to nerve-endings of organ of Corti, and thence by the audi- tory nerve to the brain. Cartilaginous framework. Ligaments. Muscles. Collects sound-waves and reflects them into the auditory canal. Pinna, or auricle External Ear 1 in. long. Auditory canal Closed internally by the drum-membrane Membrana tympani. Hairs directed outwards. Ceruminous glands secrete a yellow, pasty substance. An irregular cavity in the temporal bone. Five or six drops of water will fill it. Malleus (hammer). Incus (anvil). Stapes (stirrup). Bones . . . Middle Ear Fenestra ovalis - closed by a membrane and the stapes. Fenestra rotunda - closed by a membrane. Eustachian tube - connects with the phar- ynx, allows entrance of air. Openings. . Vestibule - antechamber just inside of fenestra ovalis. Semicircular canals Three in number. Open into vestibule. Vestibular branch of auditory nerve distrib- uted to vestibule and semicircular canals. Internal Ear Bony labyrinth A spiral tube. 2| turns. Fenestra rotunda. Cochlear branch of the auditory nerve. Cochlea 364 ANATOMY FOR NURSES [Chap. XIX ■ Surrounded by perilymph. Contains endolymph. Lines the vestibule. Lines the semicircular canals. Lines the cochlea, and here it is called the canalis cochlearis, or scala media. Membrana basilaris is name given to mem- brane at base of canal. Organs of Corti are end organs of auditory nerve lodged on membrana basilaris. Internal Ear Membranous labyrinth ' Function of the vestibule and semicircular canals. Lining membrane supplied with sensory hairs which con- nect with vestibular nerve. Contain several small otoliths which float in the endolymph. Flowing of the endolymph stimulates the sensory hairs; this is transmitted to the vestibular nerve, thence to auditory nerve, thence to brain. Sense of Equilibrium Eye Accessory organs . Optic nerve Centre in brain Eyebrows. Eyelids. Lacrimal apparatus. Muscles. Visual apparatus Sight . Vibrations in the ether enter eye and strike on retina, which contains end organs of the optic nerve; thence sensation is carried to visual centre in brain. Eyebrows Arched eminences of skin furnished with short, thick hairs. Control to a limited extent amount of light admitted to eye. ' Folds of connective tissue covered with skin, lined with mu- cous membrane (conjunctiva), which is also reflected over the eyeball. Provided with lashes. Closed by orbicularis palpebrarum muscle. Upper lid raised by levator palpebrse superioris. Slit between lids called palpebral fissure. Inner angle of slit called internal canthus. Outer angle of slit called external canthus Function is protection. Serve as shades. Tarsal glands are a row of glands embedded in tarsus of < each lid. Eyelids Lacrimal gland - in the upper and outer part of the orbit. Secretes tears. Ducts - 7 to 12 lead from gland to conjunctiva. Canaliculi - 2 canals | to | in. long, begin at puncta and open into lacrimal sac. Lacrimal sac - upper dilated portion of the nasal duct. Nasal duct - canal f in. long, extends from lacrimal sac to the inferior meatus. Lacrimal Apparatus Chap. XIX1 ORGANS OF SPECIAL SENSE 365 Secretion constant. Moistens the eyeball and helps to moisten inspired air. Tears . . , Consist of W ater. Salt. Albumin. Carried off by nasal duct. Muscles - See table at end of Chapter VI. Nerves - See Chapter XVIII. Bony cavity - formed by seven bones. Lined by capsule of Tenon. Optic foramen - large opening for pas- sage of nerves and blood-vessels. Contained in orbit Eyeball . . . . 1. Sclera and cornea. 2. Choroid, ciliary processes, and iris. 3. Retina. Tunics 1. Aqueous. 2. Crystalline lens and capsule. 3. Vitreous. Media Sclera . . ' Tough, fibrous, opaque. Protective. Covers posterior | of eyeball. Stained brown internally. Cornea Fibrous, transparent - covers anterior | of eyeball. Well supplied with nerves. ' Vascular coat, lines the sclera. Composed of connective tissue cells filled with pigment. Terminates in front by the ciliary processes. Choroid . TUNICS '70 to 80 parallel folds of the choroid, rising gradually from behind and forming a plaited zone between the choroid and iris. Support ciliary muscle - action of this muscle deter- mines the position of the lens. Ciliary processes ' A circular curtain. Central perforation -pupil. Pupil contracted by circular muscle-fibres. Pupil dilated by radial muscle-fibres. Contains pigment - amount of which determines col- our of the eyes. Hangs free except for attachment at circumference to the ciliary processes and choroid. Iris . . 366 ANATOMY FOR NURSES [Chap. XIX Visual layer - transparent membrane of nervous and connective tissue situated between the choroid and vitreous humour. Has eight layers and two membranes. Counting from the choroid inward as follows: - Pigment layer, usually described as a membrane. 1. Layer of rods and cones (perceptive layer) - ex- ternal layer. 2. Limitans externa. 3. External granules. 4. External molecular. 5. Internal granules. 6. Internal molecular. 7. Ganglion or nerve-cells. 8. Optic nerve-fibres - innermost layer. Membrana limitans interna. TUNICS Retina . . c Aqueous chamber is between cornea in front and lens, suspensory ligament and ciliary body behind. Aqueous humour is a col- ourless, transparent, watery fluid. Aqueous Semi-fluid, gelatinous substance. Fills the posterior four-fifths of the globe of the eyeball, and is enclosed in the hyaloid membrane. Distends the sclera and sup- ports the retina. Vitreous Refracting Media Situated behind the pupil. Double convex in shape. Fibrous body enclosed in an elastic capsule. Held in position by counterbalancing of the aqueous and vitreous humour and the suspensory ligament. Function is to focus the rays of light. Crystalline lens The eye is a dark chamber (camera). Rays of light converge as they enter the cornea. Convergence increased by the lens. Image (inverted) falls on the retina. Photographic function of eye Blind spot Entrance of optic nerve. There are no rods and cones. Totally insensitive to light. Macula lutea fa in. outside the blind spot. Central pit - fovea centralis - is the centre of direct vision. CHAPTER XX FEMALE GENERATIVE ORGANS The female generative organs are divided into an internal and an external group. The former are contained within the pelvis, and comprise the following structures: - (1) Ovaries, two glandular organs in which the ova are formed. (2) Uterine (Fallopian) tubes, two canals through which the ova reach the uterine cavity. (3) Uterus, a hollow, pear-shaped organ, which receives the ovum. (4) Vagina, a canal extending from the uteruS to the vulva. The external organs are grouped under the name of vulva, or pudendum, and include the vulval canal and surrounding struc- tures. THE OVARIES The ovaries are two small, almond-shaped bodies, situated one on each side of the uterus, between the anterior and posterior folds of the broad ligament, and below the uterine tubes. Each ovary is attached by its inner end to the uterus by a short liga- ment, - the ligament of the ovary, - and by its outer end to the uterine tube by one of the fringe-like processes of the fimbriated extremity. The ovaries each measure about one and a half inches (38 mm.) in length, three-fourths of an inch (19 mm.) wide, and one-third of an inch (8.5 mm.) thick, and weigh from one to two drachms (3.7 to 7.5 grammes). Their function is to produce, develop, and mature the ova, and to discharge them when fully formed, from the ovary. If an ovary be minutely examined, it is seen to be a ductless gland save in that the uterine (Fallopian) tube serves as a duct. It consists of - 367 368 ANATOMY FOR NURSES [Chap. XX 1. Stroma of connective tissue. 2. Vesicular (Graafian) follicles of different sizes. Stroma. - The stroma (bed) is a connective tissue composed of abundant cells, white and yellow fibrous tissue, and plain mus- cular fibres. It contains many blood-vessels, lymphatics, and nerves. The outer portion is more condensed than the interior, and the whole is covered by a layer of columnar epithelium cells called germinal epithelium. Vesicular follicles. - The vesicular follicles are cavities which contain the ova and are embedded in the meshes of the stroma. Fig. 210.-Uterus, Uterine Tubes, and Ovaries - Posterior View. 1, ovaries; 2, 2, uterine tubes; 3, 3, fimbriated extremity of the left uterine tube, seen from its concavity; 4, opening of the left tube; 5, fimbriated extremity of the right tube, posterior view; 6, 6, fimbriae which attach the extremity of each tube to the ovary; 7, 7, ligaments of the ovary; 8, 8, 9, 9, broad ligaments; 10, uterus; 11, cervix uteri; 12, os uteri; 13, 13, 14, vagina. (Sappey') The smaller ones lie near the surface. The larger are more deeply embedded, and only approach the surface when they are ready to discharge their contents. The follicles have each their own proper wall, or tunic, derived from the connective tissue of the stroma, and each is lined by a layer or layers of granular epithe- lium cells. The granular layer of cells, closely lining the cavity of the follicle, is termed the membrana granulosa, but at one or other side it is heaped up into a mass of cells which projects into the cavity of the follicle and envelops the ovum. This mass of Chap. XX] FEMALE GENERATIVE ORGANS 369 cells which immediately surrounds the ovum is called the ovarian mound (discus proligerus). As the follicle matures, fluid collects in the cavity, and, increas- ing in amount, the follicle gradually becomes larger and more tense. It now approaches the surface and begins to form a protuberance like a small boil upon the outside of the ovary. Finally the wall of the ovary and the wall of the follicle burst at the same point, and the ovum, with some of its surrounding epithelium, escapes. At the moment of rupture, or soon after, the ovum is received by the uterine tube and afterwards conveyed to the uterus. After the follicle has discharged its contents, it has done its work, and it passes through a series of degenerative changes, and eventually disappears. Thus in the same ovary some of the follicles are mature, or approaching maturity, while others are retrograding and disappearing. From puberty to the menopause the formation of new vesicular follicles is continuous, and a very great number are produced. The ovum. - The ovum is a highly developed cell, formed from the germ-epithelium on the surface of the ovary, the cells of which become enlarged and dip down into the stroma in the form of little balls. From this ball of epithelial cells, which is introduced into the body of the organ, one cell develops the ovum; the rest go on to make up the vesicular follicle and ovarian mound. A perfected ovum is a minute globular cell about inch (0.2 mm.) in diameter. The component parts have received special names. The cell-wall is a thick, surrounding envelope, or membrane, called the vitelline membrane, or zona pellucida. The cell-body is a mass of protoplasm filled with fatty and albuminous granules, and usually called the vitellus, or yolk. The cell nucleus, or germinal vesicle, is a transparent, sharply outlined nucleus, embedded in the vitellus, or yolk. The nucleolus, or germinal spot, is a small, dark spot situated in the fluid nucleus. It is impossible for us to trace the growth and development of the fecundated ovum. The subject is too complicated for us to attempt to describe it in a book of this kind, and we shall, therefore, content ourselves with briefly describing the first two or three steps. 370 ANATOMY FOR NURSES [Chap. XX Soon, after leaving the ovary, the cell nucleus and nucleolus in a fecundated ovum disappear, and the protoplasm begins to divide inside the vitelline membrane into two halves, in each of which appears a nucleus. The halves divide into quarters, the quarters into eighths, and so the subdivision continues until a great number of minute cells are produced, which soon arrange themselves, close to each other like bricks in a wall, upon the inner surface of the vitelline membrane. The cells thus in close contact with one another form a membrane called the ectoderm. Upon this membrane a second one soon appears, formed in the same way and lining its inner surface. This is called the en- toderm. Subsequently a third membrane, the mesoderm, is developed. It extends out on either side from the junction of the ectoderm and entoderm. From these three membranes all the tissues and complicated structures of the body are evolved. Upon the arrival of the ovum in the uterus, it is grafted upon the mucous membrane. It usually lodges upon the upper sur- face of the uterus, between two folds of the mucous lining, which soon grow up all round it, and, as it were, bury the germ in a circular bed. From the thickened mucous membrane lying be- tween the ovum and the uterine wall the placenta is ultimately formed for the nourishment of the embryo. Up to this point the ovary has been described as a true gland, the product of activity (the ovum) being carried by a duct (uter- ine tube) to the external surface of the body (cavity of the uterus). In addition, the ovary doubtless furnishes an internal secretion (picked up by the blood) profoundly affecting the individual. For the absence or presence of the gland itself produces a marked influence on the temperament of the woman not to be accounted for by the mere function of ovulation. UTERINE TUBES The uterine tubes (Fallopian tubes), or oviducts, are provided for the purpose of conveying the ova from the ovaries into the cavity of the uterus. They are two in number, one on each side, and pass from the upper angles of the uterus in a somewhat tortuous course between the folds and along the upper margin of the broad ligament, towards the sides of the pelvis. Each Chap. XX] FEMALE GENERATIVE ORGANS 371 tube is about four inches (100 mm.) in length, and is described as consisting of three portions: - (1) The isthmus, or inner constricted half. (2) The ampulla, or outer dilated portion, which curves over the ovary. (3) The infundibulum, or trumpet-shaped extremity, the mar- gins of which are frayed out into a number of fringe-like pro- cesses called fimbriae. One of these fimbriae is attached to the ovary. The uterine opening of the tube is minute, and will only admit a fine bristle; the abdominal opening (ostium abdominale) is comparatively much larger. The uterine tube consists of three coats: - (1) Serous. -The external, or serous coat, is derived from the peritoneum. (2) Muscular. - The middle, or muscular coat, has two lay- ers : one a layer of longitudinal fibres and the other of circular fibres. (3) Mucous. - The internal, or mucous coat, is continuous at the inner end with the mucous lining of the uterus, and at the distal end with the serous lining of the abdominal cavity. This is the only instance in the body in which a mucous and serous lining are continuous with one another. When the ovum is ready for entrance into the uterine tube, the fimbriae of the free end grasp the ovary, the tiny germ-cell is safely conducted into the trumpet-shaped extremity, and is thence carried along by the peristaltic motion of the oviduct into the uterus. This transmission of the cell is also assisted by the ciliated epithelium lining the tube, the motion of the cilia wafting it onwards. It frequently happens that ova are expelled from the ovary and miss the mouth of the fimbriated end of the uterine tube. Under such circumstances the ovum lodges in the peritoneal cavity and usually dies, but occasionally becomes impregnated (ectopic gestation). THE UTERUS The uterus is a thick-walled, hollow, pear-shaped organ, situ- ated in the pelvis, between the bladder and the rectum. Its upper end is a little below the level of the superior strait of the 372 ANATOMY FOR NURSES [Chap. XX pelvis; its lower end projects into the vagina. Its length is esti- mated to be about three inches (75 mm.), its width two inches (50 mm.), and its thickness one inch (25 mm.). At the end of pregnancy it attains the length of a foot (300 mm.) or more, and measures about eight to ten inches (200 to 250 mm.) transversely. The uterus is divided for purposes of description into three parts: the fundus, body, and neck. The fundus is the rounded portion projecting above a line drawn transversely through the upper margin of the cavity. Fig. 211. - Internal Organs of Generation. Showing the uterus in its normal position between the bladder and the rectum. (Cooke.) The body is the portion extending from the rounded section, the fundus, to the constricted section, the neck. The neck, or cervix, extends from the body of the uterus into the vagina. Owing to the thickness of its walls, the cavity of the uterus is comparatively small. The cavity is triangular in shape (v), and has three openings, one at each upper angle, communicating with the uterine tubes, and one, the internal orifice, opening into Chap. XX] FEMALE GENERATIVE ORGANS 373 the cavity of the cervix below. The cavity of the cervix, which is, of course, continuous with the cavity in the body, is con- stricted above, where it opens into the body by means of the in- ternal orifice (internal os) and below, where it opens exteriorly by means of the external orifice (external os). Between these two openings the canal of the cervix is somewhat enlarged. The uterus consists of three coats: - (1) Serous. - It is derived from the peritoneum. It covers nearly all the external surface. (2) Muscular. -■ The walls of the uterus consist mainly of bundles of plain muscular tissue, arranged in layers, which run circularly, longitudinally, spirally, and cross and interlace in every direction. (3) Mucous membrane. - This lines the uterus, and is con- tinuous with that lining the vagina and uterine tubes. It is highly vascular, provided with numerous mucous glands, and is covered with ciliated epithelium. Blood supply of uterus. - The uterus is abundantly supplied with blood-vessels, lymphatics, and nerves. The blood reaches the uterus by means of the uterine arteries from the internal iliacs, and the ovarian arteries from the aorta. Where the neck joins the body of the uterus, the arteries from both sides are united by a branch vessel, called the circumflex artery. If this branch is cut during a surgical operation, or a tear of the neck during parturition extends so far as to sever it, the hemorrhage is very profuse. The arteries are remarkable for their tortuous course and frequent anastomoses. The veins are of large size, and correspond in their behaviour to the arteries. During pregnancy all the tissues of the uterus become much enlarged, undergoing what is called a physiological hypertrophy. The uterus increases in weight from two or three ounces (60 to 90 grammes) to two or three pounds (960 to 1440 grammes). After parturition, it goes back to nearly its former size. The tissues all go through a gradual shrinkage, or what is called a physiological atrophy. The enlarged muscles especially undergo fatty degeneration and absorption, called "involution," in con- tradistinction to "evolution," or development. This process of involution is not accomplished under six weeks, and sometimes requires longer. 374 ANATOMY FOR NURSES [Chap. XX The uterus is not firmly attached or adherent to any part of the skeleton. It is, as it were, suspended in the pelvic cavity, and kept in position by ligaments. A full bladder pushes it back- ward; a distended rectum, forward. It alters its position, by gravity, or with change of posture. During gestation it rises into the abdominal cavity. The fundus of the uterus is inclined forward, and the external orifice is directed downward and backward. (See Fig. 211.) Anteversion is the con- dition where the fundus turns too far forward. Retroversion is the con- dition where the fundus inclines backward. A bend may exist where the neck joins the body, and if the body is bent forward, it is described as ante- flexion; if bent backward, retroflexion. Ligaments. - The uterus is maintained in position by five ligaments. Three are arranged in pairs. 1. The broad, or lateral ligaments, two in number, are folds of peritoneum slung over the front and back of the uterus, and extending laterally to the walls of the pelvis. They are composed of two opposed, serous layers, and between these layers are found the following structures: - (a) Uterine tube; (6) the ovary and its ligament; (c) the round ligament; (d) blood-vessels and lymphatics; (e) nerves; (/) some smooth muscle-fibres. The posterior fold covers the back of the uterus, and extends far enough below to also cover the upper one-fifth of the back wall of the vagina, when it turns up and is reflected over the anterior wall of the rectum. Thus the uterus, with and between its two broad ligaments, forms a transverse partition in the pelvic cavity, the bladder, vagina, and urethra being in the front compartment, and the rectum in the back compartment. The smooth muscular fibres of the broad ligaments are derived from the superficial muscular layer of the uterus. They pass out between the serous folds and become attached to the pelvic fascia, and thus help to sustain the uterus. 2. The round ligaments are two rounded, fibro-muscular cords, situated between the folds of the broad ligament. They are about four and a half inches (113 mm.) long, and take their origin from the upper angle of the uterus (on either side) in front and a little below the attachment of the uterine tube. They extend forward and outward, and finally end in the tissues of the labia majora Chap. XX] FEMALE GENERATIVE ORGANS 375 and mons Veneris. The round ligaments are composed of muscle- fibres, areolar tissue, blood-vessels, and nerves. 3. The utero-sacral ligaments extend between the cervix and sides of the rectum. They serve to connect the cervix and vagina with the sacrum, and are partly serous, partly of smooth muscular fibres. 4. Anterior ligament. - Between the bladder and uterus the peritoneum forms a shallow pouch called the utero-vesical pouch. This peritoneum, which forms the floor of the pouch, is described as the anterior ligament of the uterus. 5. Recto-vaginal. - Behind the uterus the peritoneum forms a second and deeper pouch called the recto-vaginal, or cul-de-sac, of Douglas. This peritoneum is described as the recto-vaginal ligament. THE VAGINA The vagina (sheath) is a distensible and curved musculo-mem- branous canal, extending from the uterus to the vulva. It is DORSAL VEIN<^ ©F CLITORIS PREPUCE OF- CLITORIS GLANS CLI- TQRIDIS Fig. 212. - Sagittal Section of the Vagina and Neighbouring Parts (Gerrish.) lined with mucous membrane, which in the ordinary contracted state is thrown into folds, its anterior and posterior walls being in contact. The posterior wall is about three and a half inches (88 mm.) 376 ANATOMY FOR NURSES [Chap. XX long, while the anterior wall is only three inches (75 mm.). The front, or anterior wall, is united by connective tissue with the posterior walls of the bladder and urethra, the partition, or septum, between the bladder and vagina being called the vesico- vaginal, and that between the urethra and vagina the urethro- vaginal, septum. If we divide the posterior wall of the vagina into five sections, we find that the middle three-fifths is connected with the rectum, the united walls of rectum and vagina forming the recto-vaginal septum; the lower fifth is separated from the rectum and is joined to the perineum; while the upper fifth extends up behind the neck of the uterus. Perforations of the recto-vaginal and vesico-vaginal partitions constitute recto-vaginal and vesico-vaginal fistulae. The vagina is made up of three coats: an outer, fibrous; mid- dle, muscular; and inner, mucous. The muscular coat increases during pregnancy, and the mucous coat, because of the transverse folds, or rugae, allow of dilatation of the canal during labour and birth. THE VULVA The vulva includes the following parts: - 1. Mons Veneris, the labia majora, and the labia minora. 2. Interlabial, or vulval cleft. 3. Clitoris. 4. Certain glandular structures. Mons Veneris. - The mons Veneris is a cushion of fibrous and adipose tissue in front of the body^of the pubic bone, covered after puberty with hair. Labia majora. - The labia majora ("greater lips") are two folds of skin containing adipose and connective tissue. They are continuous with the mons Veneris in front, and extend to within an inch (25 mm.) of the anus behind. Labia minora. - The labia minora ("smaller lips") are two folds situated between the labia majora, about one and one-half inches (38 mm.) long, and joined anteriorly in the hood or pre- puce of the clitoris. Interlabial cleft. - The interlabial space is the cleft, or fissure, which is bounded on either side by the labia majora and minora. Chap. XX] FEMALE GENERATIVE ORGANS 377 It receives the orifice of the vagina, which in the virgin is partially closed by a fold of mucus membrane called the hymen.1 It also receives the orifice of the urethra or external meatus. Clitoris. - The clitoris is a small body, less than one inch (25 mm.) in length, and nearly covered by the hood or prepuce. It contains many vessels and nerves. Glands. - In connection with the vulva are found - (1) Vulvo-vaginal, (2) Urethral glands. The vulvo-vaginal, or glands of Bartholin, are round, or oval, glands, about one-half inch (12.5 mm.) in their longest diameter, and situated on either side of the vagina. Their ducts open into the vulval canal, one on either side, in the groove between the hymen and labia minora. Their secretion lubricates the vulval canal. The urethral glands are found chiefly beneath the lateral walls and floor of the urethra. They secrete mucus, and their open- ings are arranged in rows parallel with the long axis of the canal. Perineum. - The perineum properly signifies the parts bounded by the outlet of the pelvis, but we generally apply it to the triangular portion between the vagina and rectum. It is made up of muscles strengthened with very strong fasciee. It is dis- tensible, and stretches to a remarkable extent during labour. MAMMARY GLANDS The two mammary glands, or breasts, may be considered as accessory organs of generation. Each one covers a nearly circular space in front of the pectoral muscles, extending from the second to the sixth rib, and from the sternum to the border of the arm- pit. They are compound glands, and are divided by connective tissue partitions into about twenty lobes, each of which possesses its own excretory duct opening by a separate orifice upon the 1 The ragged edges left by rupture of the hymen are called " carunculae myrtiforines." An imperforate hymen is one which extends entirely across the vaginal orifice, closing it altogether. 378 ANATOMY FOR NURSES [Chap. XX surface of the nipple. The lobes are subdivided, and the small lobes, or lobules, are made up of the terminal tubules of the duct, which lie in a mesh of fibrous areolar tissue containing consider- able fat. The walls of the ducts and the terminal tubules are formed of a basement membrane lined by epithelium cells. The main ducts (lactiferous) are sacculated, and during lactation the se- cretion (milk) collects in them and is drawn from them through their small orifices in the nipple. The breasts are abundantly supplied with blood-vessels, lymphatics, and nerves. Milk. - Human milk is a bluish white fluid, alkaline in re- action, and has a specific gravity of about 1030. The average composition of the milk of different animals is as follows: - Chemical composition of milk: - Human Cow Goat Water 87.30 87. 86.5 Solids 12.70 13. 13.5 Fats 4. 4. 4.3 Proteids 1.50 4. 4.6 Sugar 7. 4.3 4. Salts .20 .7 .6 During lactation the secreting cells become much enlarged, and fatty globules are formed within them. The fatty globules appear to be set free by the breaking down of the inner part of the cell, the protoplasm becoming dissolved also, and forming the proteid substances of the milk. At the beginning of lacta- tion the cells are imperfectly broken up, so that numerous cells containing comparatively large masses of fat (the colostrum corpuscles) appear in the secretion. FUNCTIONAL ACTIVITY OF FEMALE GENERATIVE ORGANS Under this heading we have two manifestations to study, viz. ovulation and menstruation. Both of these events are closely associated with the child-bearing period of a woman's life, and are also closely associated together. Much dispute has arisen over the association of menstruation and ovulation, and without attempting to weigh the comparative merits of Chap. XX] FEMALE GENERATIVE ORGANS 379 the different theories, we shall accept and describe only those most generally accepted. Menstruation. - This is a phenomenon inherent in all women between puberty and the menopause. It consists of a flow of blood from the uterus, together with an exfoliation of part or of the whole of the mucous membrane of the uterus. At the menstrual period there are, in addition, certain physical and psychical manifestations involving to a more or less degree the entire individual. By puberty is meant that age at which a woman begins her functional (child-bearing) existence. In temperate climates we may say the average age is fourteen years. In southern countries it is somewhat earlier, and in the arctic regions, a year or two later. However, no fixed rule can be given, as the time of arrival at puberty varies with every individual, depending on race, temperament, hygiene, and general surroundings. At puberty is the time when the girl changes into the woman. The event is not accomplished at once, but extends over con- siderable time. The girl undergoes a gradual change in figure, the hips broaden, the breasts develop, and for the first time a menstrual flow is noticed. At first the menstrual periods are scanty and irregular, but after a few months they settle down to the characteristic rate and duration. By menopause, or climacteric, is meant the physiological ces- sation of the menstrual flow. The woman's functional activ- ity is over. The ovaries become smaller; no more vesicular (Graafian) follicles are developed; and the uterine (Fallopian) tubes atrophy. The age of menopause varies as does the age of puberty; in general, we may say the earlier the puberty the later the menopause, and vice versa. In temperate climates the average period for the arrival of the menopause is at the age of forty-five years. Thus we see a woman's functional activity lasts thirty years. Frequency of menstruation. - When once established, men- struation occurs on the average every twenty-eight days, although it is not without the bounds of normal health for some women to have a menstrual flow every twenty-one days, and others do not menstruate oftener than once in six weeks. Menstruation is in abeyance during pregnancy and lactation. 380 ANATOMY FOR NURSES [Chap. XX Duration of menstruation. - The menstrual flow lasts on an average five days, the amount of blood lost gradually increasing until the third day, and then gradually diminishing. Nature of menstruation. - At the beginning of menstruation there is a general congestion of the generative organs, including the breasts. A few days before menstruation there has de- veloped a hypertrophy of the mucous membrane (superficial layers) of the uterus. At the beginning of the menstrual period this hypertrophied mucous membrane is gradually shed, leaving its underlying vessels exposed, and they bleed. At the end of menstruation a new mucous membrane is developed. The shed mucous membrane is called the "decidua menstrualis." During menstruation, especially at the beginning of the period, the woman is apt to be peevish, irritable, complains of head- ache, loss of appetite, and a sense of pelvic oppression that may even amount to severe pain. Character of menstrual discharge. - It is a thin, bloody fluid of a dark colour and having a peculiar odour. It consists of blood, epithelium, and mucus from the uterus and vagina, together with the decidua menstrualis. The blood does not clot. Ovulation. - The commonly accepted theory is that about or shortly before the age of puberty the vesicular (Graafian) follicles begin to discharge their ova, and that this process con- tinues until the menopause. Doubtless many vesicular (Graafian) follicles only partially develop and atrophy without discharging mature ova. The frequency with which well-developed ova are discharged is the subject of much dispute. The most con- servative view is that there is one mature ovum discharged for each menstrual epoch. On the other hand, other embryol- ogists claim that there is an almost daily discharge of ova, but only a few enter the uterine (Fallopian) tubes, while the rest are lost in the peritoneal cavity. Whichever view the student cares to follow is immaterial, but nevertheless we must agree that only about as many mature ova reach the uterine cavity as there are menstrual epochs. On leaving the ovary and entering the uterine (Fallopian) tube, the ovum is surrounded by a few cells derived from the ovarian mound (discus proligerus) of the vesicular (Graafian) Chap. XX] FEMALE GENERATIVE ORGANS 381 follicle. These cells may serve as a source of nourishment, but soon disappear, and if impregnation does not take place, the ovum dies and is cast off. If impregnation does occur, there is further development of the ovum. Corpus luteum. - After the escape of an ovum, there is an effusion of blood into the cavity of the vesicular (Graafian) follicle. The clot which follows is disposed of by the same retrogressive processes which extravasated blood may undergo in any part of the body. The serum is absorbed, the cells dis- integrate, and the colouring matter is in part taken up by the tissues and in part crystallizes or takes up other constituents, and presents variations of colouring. Hand in hand with these changes in the blood go important changes in the surrounding tissue. The epithelial cells which are left behind proliferate and form a sort of yellowish, very vascular tissue. This yellow mass surrounding and enclosing the remains of the extravasated blood constitutes the corpus luteum. Recent work tends to support the theory that the corpus luteum is a gland which forms an internal secretion, and this secretion has a direct influence on the cycle of menstruation. The corpus luteum is renewed every four weeks. It reaches a certain size, then atrophies, and its place is occupied by a dense, firm connective-tissue cicatrix, which may be pig- mented. The changes described above are those that take place if the ovum fails to become impregnated. If, on the other hand, fecundation occurs, the corpus luteum undergoes certain char- acteristic changes, widely differing from the degeneration of the corpus luteum of non-pregnancy. If the ovum be impreg- nated, the corpus luteum then does not degenerate and dis- appear rapidly, as after menstruation, but continues fuily as large as at the beginning for several months, and at the end of pregnancy still remains as a clearly marked body. Connection between ovulation and menstruation. - Whether ovulation depends upon menstruation or menstruation upon ovulation, or whether either has any connection with the other, is a matter of lengthy controversy. However, the general view is that both ovulation and men- struation are the result of a common cause (cause unknown), but either may exceptionally occur without the other. 382 ANATOMY FOR NURSES [Chap. XX It is generally accepted that ovulation, or discharge of ovum from a vesicular (Graafian) follicle, takes place a few days before the onset of the menstrual period. SUMMARY Female Generative Organs Internal. External, or vulva. Ovaries, two ^Stroma of connective tissue, glandular organs ; Vesicular follicles. Uterine tubes, two canals. Uterus, a hollow, pear-shaped organ. Vagina, a canal that extends from uterus to vulva. Internal Organs ' Cell-wall = zona pellucida. Cell-body = protoplasm. Cell nucleus = germinal vesicle. Nucleolus = germinal spot. ~ . „ , . . Ovum - A cell formed m the ovary Enclosed in layers of broad ligament. 1. Isthmus - or inner constricted portion near uterus. 2. Ampulla - dilated portion -which curves over ovary. 3. Infundibulum - trumpet-shaped extremity - fimbriae. Convey ova to uterus Uterine Tubes 1. External or serous. 2. Middle, or muscular. 3. Internal, or mucous. Three coats Hollow, thick-walled organ, placed in pelvis between bladder and rectum. Fundus = rounded upper portion. Body = portion below fundus, above neck. Cervix = lower and smaller portion which ex- tends into vagina. Divisions Uterus . External, or serous, derived from peritoneum. Circular fibres Longitudinal fibres Spiral fibres I Interlaced in J. every direc- tion. Three coats Muscular Mucous membrane, lines the uterus. Chap. XX] FEMALE GENERATIVE ORGANS 383 ' Uterine arteries from internal iliacs. Ovarian arteries from aorta. Remarkable for tortuous course and frequent anastomoses. Blood- vessels ' Broad, or lateral - two layers of serous mem- brane. Round - two fibro-muscular cords. Utero-sacral-two partly serous, partly mus- cular, ligaments. Anterior - peritoneal floor of the utero-vesical pouch. Recto-vaginal - peritoneal floor of the recto- . vaginal pouch. Uterus . Ligaments Canal - extends from uterus to vulva. Vagina . Three coats Outer coat is fibrous. Middle coat is muscular. Mucous coat, or lining, arranged in rugae. Placed between urethra and rectum. ' Mons Veneris - a cushion of fibrous and adipose tissue, in front of pubic bone. Labia majora- two folds that extend from the mons Vene- ris to within an inch of the anus. Labia minora - two folds situated between the labia majora. Interlabial space-cleft between labia majora and minora. Receives orifice of vagina and urethra. Clitoris - small body, situated at apex of the vestibule. Vulva. . Vulvo-vaginal - oval bodies situated on either side of the vagina. Urethral - glands found chiefly between the lat- eral walls and floor of urethra. Glands Perineum - triangular space between the vagina and the rectum. Accessory organs of generation. Location ' Extend from second to sixth rib. Sternum to armpit. 1. Consists of connective tissue framework which divides the gland into about twenty lobes. 2. Lobes are subdivided into lobules. 3. Lobules are made up of the terminal tubules of the duct. 4. Each lobe possesses its own excretory duct, which is called lactiferous and is sacculated. 5. Secretion of the breasts is first colostrum and then milk. Breasts . 384 ANATOMY FOR NURSES [Chap. XX Bluish white fluid. Alkaline reaction. Specific gravity, 1030. W ater. Proteids. Fats. Sugar. Salts. Human Milk Composition ' Ovulation - discharge of ova. Begins at puberty, or the average age of fourteen years. Menstruation - a flow of blood from the uterus. Occurs on an average every twenty-eight days. Extends from pu- berty (14 years) to the menopause, or climacteric (about 45 years). This period represents the child-bearing period of a woman's life. Functional Activity of Female Generative Organs METRIC SYSTEM The area of the figure within the heavy lines is that of a square decimetre. A cube, one of whose sides is this area, is a cubic decimetre or litre. A litre of water at the temperature of 4° C. weighs a kilogramme. A litre is 2.11 pints or 33.81 ounces. A pint is 0.473 of a litre. (Liquid measure.) A litre is 1.76 pint. A pint is 0.568 litre. (Dry measure.) The smaller figures in dotted lines represent the areas of a square centimetre and of a square inch. A cubic centimetre of water at 4° C. weighs a gramme. Square Inch Square Centi- metre 1 Gramme = 15.432 grains. 1 Decigramme = 1.543 grains. 1 Centigramme = .154 grain. 1 Milligramme = .015 grain. 1 Dekagramme = 154.323 grains. 1 Hektogramme = 1543.235 grains. 1 Kilogramme = 15432.350 grains. 1 Kilogramme = 35.274 ounces. 1 Kilogramme - 2.204 pounds. 1 Metre = 39.370432 inches. 1 Decimetre = 3.937043 inches. 1 Centimetre = .393704 inch. 1 Millimetre = .039370 inch. Avoirdupois weights are used in weighing the organs of the body. One ounce avoirdupois = 28.35 grammes. 385 GLOSSARY Abdo'men. [From the Lat. abdo, to "conceal."] The largest cavity of the body, containing the liver, stomach, intestines, etc.; the belly. Abdu'cens. [From the Lat. ab, "from," and duco, to "lead."] A term applied to the sixth pair of cranial nerves which supply the external recti (abductor), muscles of the eye. Abduc'tion. [From the Lat. ab, "from," and duco, to "lead."] Drawn away from the middle line of the body. Absorption. [From the Lat. ab, "from," and sorbeo, to "suck up."] The process of taking up into the vascular system either food from the alimentary canal, or other substances from the various tissues. Acetab'ulum. [From the Lat. acetum, "vinegar."] A name given to the cup-shaped cavity in the os innominatum, resembling in shape an old-fashioned vinegar vessel. Acro'mion. [From the Gr. akron, "summit," and omos, the "shoulder."] The triangular-shaped process at the summit of the scapula. Acromeg'aly. [From the Gr. akron, an " extremity," and megas, "great."] A disease characterized by an overgrowth of the extremities and the face as well as the soft parts. Adduc'tion. [From the Lat. ad, "to," and duco, to "lead."] Brought to or nearer the middle line of the body. Ad'enoid. [From the Gr. aden, a "gland," and eidos, "form," or "re- semblance."] Pertaining to, resembling a gland. Ad'ipose. [From the Lat. adeps, "fat."] Fatty. Adre'nal. [From the Lat. ad, "to," and renes, the "kidney."] Same as supra-renal. One of a pair of small glands that cap the kidneys. Af'ferent. [From the Lat. ad, "to," and fero, to "bear," to "carry."] Bearing or carrying inwards, as from the periphery to the centre. Ag'minated. [From the Lat. agmen, a "multitude;" a "group."] Ar- ranged in clusters, grouped. 387 388 GLOSSARY Albu'min. [From the Lat. albus, "white."] Animal albumin is the chief solid ingredient in the white of eggs. Albuminu'ria. [A combination of the wrords "albumin" and "urine."] Presence of albumin in the urine. Aliment'ary. [From the Lat. alimentum, "food."] Pertaining to ali- ment, or food. Alimentation. The act of receiving nourishment. Alve'olar. [From the Lat. alveolus, a "little hollow."] Pertaining to the alveoli, the cavities for the reception of the teeth. Alve'oli. Plural of alveolus. Any little cell, pit, cavity, fossa, or socket. Socket of a tooth or an air-cell. Amoe'ba. [From the Gr. ameibo, to "change."] A single-celled, pro- toplasmic organism, which is constantly changing its form by pro- trusions and withdrawals of its substance. Amce'boid. Like an amoeba. Amphiarthro'sis. [From the Gr. ampho, "both," and arthron, a "joint."] A mixed articulation; one which allows slight motion. Ampul'la. Any flask-shaped dilatation. The dilated part of the membranous semicircular canals in the ear. Amylop'sin. [From the Gr. amylum, "starch," and opsis, "appear- ance."] A ferment of the pancreatic juice that has the power to change starch into malt sugar, or maltose. Anabol'ic. [From the Gr. ana, "up," and ballo, to "throw," or "build."] Pertaining to anabolism, the process by means of which simpler elements are built up into more complex. Anaesthe'sia. [From the Gr. a, an, "without," and aisthanomai, to "perceive," to "feel."] A condition of insensibility. Anastomo'sis. [From the Gr. ana, "by," "through," and stoma, a "mouth."] Communication of branches of vessels with one another. An'nular. [From the Lat. annularis, "relating to a ring."] Ring-like ligaments found at some of the joints. Aor'ta. [From aorte, to "carry."] The great artery that carries blood from the left ventricle of the heart. Apnce'a. [From the Gr. a, "without," and pnoea, "breath."] Absence of breathing. Aponeuro'sis. [From the Gr. apo, "from," and neuron, a "nerve."] A fibrous membranous expansion of a tendon; the nerves and tendons were formerly thought to be identical structures, both appearing as white cords. GLOSSARY 389 Arach'noid. [From the Gr. arachne, a "spider," a "spider's web,"and eidos, "form," or "resemblance."] Resembling a web. The middle of the three membranes of the brain and spinal cord. Arboriza'tions. A growth or an appearance resembling the figure of a tree or plant. Are'olar. [From the Lat. areola, a "small space," dim. of area.] A term applied to a connective tissue containing small spaces. Ar'tery. [From the Gr. aer, "air," and tereo, to "keep."] Literally, an air-keeper (it being formerly believed that the arteries contained air). A tube which conveys blood from the heart to all parts of the body. Arte'rioles. [Arteriola, dim. of Lat. arteria, "artery."] A small artery. Arrec'tor. [From the Lat. ar rectus, "set up erect."] That which arrects. The arrector of the hair. Erector more usual word. Arthro'dia. [From the Gr. arthron, a "joint."] A variety of movable joint. Artic'ular. Pertaining to an articulation or joint. Articulation. [From the Lat. articula, to "form a joint."] The more or less movable union of bones, etc.; a joint. Asphyx'ia. [From the Gr. a, "without," and sphyxis, the "pulse."] Literally, without pulse. Condition caused by non-oxygenation of the blood. Assimilation. [From the Lat. ad, "to," and similis, "like."] The conversion of food into living tissue. Attas. The first cervical vertebra by which the head articulates with the spinal column, so called because it supports the head as Atlas was fabled to uphold the sky. At'rcphy. [From the Gr. a, "without," and trophe, "nourishment."] Wasting of a part from lack of nutrition. Aud'itory. [From the Lat. audio, auditum, to "hear."] Pertaining to the sense or organ of hearing. Augmentation. The act of increasing or making larger by addition, expansion, or dilatation. Aur'icle. [From the dim. of Lat. auris, the "ear."] A little ear, a term applied to the ear-shaped cavities of the heart. Auric'ulo-ventric'ular. Pertaining to the auricles and ventricles of the heart. Automatic. [From the Gr. automatos, "self-moving."] Not voluntary not under the control of or affected by volition. 390 GLOSSARY Ax'illary. Pertaining to or contained in the axilla or armpit. Axis cylinder. Same as axon. The prolonged process of the nerve- cell which is continued as the central and essential part of the nerve- fibre. Az'ygos. [From the Gr. a, "without," and zygos, a "yoke."] Without a fellow; hence, unpaired, single. Bi'ceps. [From the Lat. bis, "twice," and caput, the "head."] A term applied to muscles having a double origin or two heads. Bicus'pid. [From the Lat. bis, "twice," and cuspis, the "point of a spade."] Having two points. Blas'toderm. [From the Gr. blastos, a "bud," and derma, "skin."] The primitive membrane or layer of cells resulting from the subdivision of the germ. Brach'ial. [From the Lat. brachium, the "arm."] Belonging to the arm. Brachio-cephal'ic. [From the Lat. brachium, the "arm," and cephalicus, "of or pertaining to the head."] Of or pertaining both to the upper arm and the head; as the brachio-cephalic (innominate) artery and veins. Bron'chi. [From the Gr. bronchos, the "windpipe."] Either of the two main branches of the trachea. Bron'chioles. A small bronchial tube. Buc'cal. [From the Lat. bucca, the "cheek."] Pertaining to the cheek; the mouth cavity formed chiefly by the cheeks. Buc'cinator. [From the Lat. bucinare, "blow a trumpet."] The trum- peter's muscle. A thin, flat muscle that helps to form the wall of the cheek. Bur'sal. [From the Gr. bursa, a "bag."] Pertaining to bursoe, mem- branous sacs. But'tock. Either of the two protuberances which form the rump in men and animals. The gluteal region of the body. Butyr'ic Acid. [From the Lat. butyrune, "butter."] A colourless liquid having a strong rancid smell and acrid taste. C3H7COOH. Cae'cum. [From the Lat. coccus, "blind."] The blind gut. Calca'neum. [From the Lat. calx, the "heel."] The bone of the heel.. Caly'ces, pl. of Ca'lyx. [From the Gr. kalyx, a "cup."] Anatomists have given this name to small cwp-like membranous canals, which surround the papillae of the kidney, and open into its pelvis. GLOSSARY 391 Canalic'ulus, pl. Canalic'uli. [Dim. of Lat. canalis, a "channel."] A small channel, or vessel. Cancellated. [From the Lat. cancelli, "lattice-work."] A term used to describe the spongy lattice-work texture of bone. Ca'nine. [From the Lat. canis, a "dog."] Name given to the third tooth on each side of the jaw; in the upper jaw it is also known as the eye-tooth, pointed like the tdsks of a dog. Can'thus. [From the Gr. kanthos, the "angle of the eye."] The angle formed by the junction of the eyelids, the internal being the greater, the external the lesser, canthus. Cap'illary. [From the Lat. capillus, "hair."] A minutely fine vessel, resembling a hair is size. Carbohy'drates. A general name for a group of organic bodies, contain- ing carbon, hydrogen, and oxygen; the two latter in the proportion in which they form water, (H.,O), that is, twice as many hydrogen as oxygen atoms. Car'bon. An elementary body, the principal element of organized bodies. Car'bon Diox'ide (CO2). A compound of carbon and oxygen. Car'dio-inhib'itory. [From the Lat. cardia, "heart," and inhibere, to "restrain."] An agent which restrains the heart's action. Carot'ids. [Perhaps from the Gr. karos, "stupor," because pressing on them produces stupor.] The great arteries conveying blood to the head. Car'pus. [From the Gr. karpos, the "wrist."] The assemblage of bones forming the wrist. Ca'sein. [From the Lat. caseus, "cheese."] The albumin of milk; the curd separated from milk by the addition of rennet, constituting the basis of cheese. 1 Car'tilage. [From the Lat. cartilago, "gristle."] A solid but flexible ma- terial, forming a part of the joints, air-passages, nostrils, etc. Gristle. Caud'a Equi'na. [Lat.] "Horse-tail." A term applied to the termina- tion of the spinal cord, which gives off a large number of nerves which, when unravelled, resemble a horse's tail. Cau'date. [From the Lat. cauda, a "tail."] Tail-like. Centrif'ugal. [From the Lat. centrum, the "centre," and fugere, "flee."] Flying off or proceeding from the centre. Centrip'etal. [From the Lat. centrum, the "centre," and petere, "seek, move toward."] Tending or moving toward the centre. Opposed to centrifugal. 392 GLOSSARY Cerebel'lum. [Dim. of Lat. cerebrum, the "brain."] The hinder and lower part of the brain; the little brain. Cer'ebrum. [Lat. the "brain."] Chief portion of brain. Ceru'minous. [From the Lat. cerumen, "ear-wax."] A term applied to the glands secreting cerumen, ear-wax. Cer'vix. [Lat.] The neck (little used). Part of an organ likened to a neck. Choles'terin. [From the Gr. chole, "bile," and stear, "fat."] A taste- less, inodorous, fatty substance formed in the bile. Chon'drin. [From the Gr. chondros, "cartilage."] A kind of gelatin obtained by boiling cartilage. Chor'dae Tendin'eae. [Lat.] Tendinous cords. Chor'da Tympani. [Lat.] The tympanic cord, a branch of the facial, or seventh cranial, nerve which traverses the tympanic cavity and joins the gustatory, or lingual nerve. Cho'roid. [From the Gr. chorion, "skin," and eidos, "form," or "resemblance."] A skin-like membrane; the second coat of the eye. Chyle. [From the Gr. kulos, "juice."] Milky fluid of intestinal digestion, found in the lymphatics of the intestines. Chyme. [From the Gr. kumos, "juice."] Food that has undergone gastric but not intestinal digestion. (Both chyle and chyme signify literally liquid, or juice.) Cica'trix. [Lat. a "scar."] The mark, or scar, left after the healing of a wound. Cil'ia. [Lat. the "eyelashes."] Hair-like processes of certain cells. Ciliary. Pertaining to the cilia. Ciliated. Provided with cilia. Circumvaliate. [From the Lat. circumvallo, to "surround with a wall."] Surrounded by a wall. Clavicle. [From the dim. of Lat. clavis, a "key."] The collar-bone, so named from its shape. Climacteric. A critical period in life, or a period in which some great change is supposed to take place in the human constitution; espe- cially the so-called change of life, or menopause. Coagula'tion. [From the Lat. coag'ulo, to "curdle."] Applied to the process by which the blood clots or solidifies. Coc'cyx. [Lat. the "cuckoo."] The lower curved bone of the spine, resembling a cuckoo's bill in shape. GLOSSARY 393 Coch'lea. [Lat. a "snail," a "snail-shell"; hence, anything spiral.] A term applied to a cavity of the internal ear. Coe'liac. [From the Gr. koilos, "hollow."] Pertaining to the ab- dominal cavity. Collaterals. [From the Lat. con, "together," and lateralis, "of the side."] Situated at the side; hence, also secondary. Codon. [Gr. kolon.~\ That portion of the large intestine which extends from the csecum to the rectum. Colos'trum. First milk secreted after labour. Colum'nae Car'neae. [Lat.] "Fleshy columns"; muscular projections in the ventricles of the heart. Colum/nar. Formed in columns; having the form of a column. Com'missure. [From the Lat. con, "together," and mitto, missum, to "put."] A joining or uniting together. Something which joins together. Con'cha. [Lat. a "shell."] A term applied to the hollow portion of the external ear. Con'dyloid. [From the Gr. kondulos,& "knob," or "knuckle," and eidos, "likeness."] A term applied to joints and processes of bone having flattened knobs or heads. Conjunctiva. [From the Lat. con, "together," and jungo, junctum, to "join."] A term applied to the delicate mucous membrane which lines both eyelids and covers the external portion of the eyeball. Convolutions. [From the Lat. con. and vol'vo, to "roll together."] The tortuous foldings of the external surface of the brain. Co'rium. [Lat. the "skin."] The deep layer of the skin; the derma. Cor'nea. [From the Lat. cornu, a "horn."] The transparent anterior portion of the eyeball. Coro'nal. [From the Lat. corona, a "crown."] Pertaining to the crown. Cor'onary. [From the Lat. corona, a "crown."] A term applied to vessels, ligaments, and nerves which encircle parts like a crown, as the coronary arteries of the heart. Cor'pora Aran'tii. [From the Lat. corpus, the "body."] Fibro-cartilagi- nous nodules situated one in the centre of the free edge of each of the segments of the aortic and pulmonary valves. Named from Aranzi, an Italian anatomist. Cor'pus Callo'sum. [Lat.] "Callous body," or substance. A name given to the hard substance uniting the cerebral hemispheres. 394 GLOSSARY Cor'puscle. [From the dim. of Lat. corpus, a "body."] A small body, or particle. Cor'tex. [Lat. "bark."] External layer of kidney; external layer of brain. Cos'tal. [From the Lat. costa, a "rib."] Pertaining to the ribs. Coxa, pl. Coxae. [From the Lat. coxa, "hip."] The hip bone, os coxae, or os innominatum. Cra'nium. [Lat.] The skull. Crassamen'tum. [From the Lat. crassus, "thick."] The thick deposit of any fluid, particularly applied to a clot of blood. Crena'ted. [From the Lat. crena, a "notch."] Notched on the edge. Crib'riform. [From the Lat. cribrum, a "sieve," and forma, "form."] Perforated like a sieve. Cri'coid. [From the Gr. kri'kos, a "ring."] A cartilage of the larynx resembling a seal-ring in shape. Cru'ra Cer'ebri. [From the Lat. crus (pl. crura), a "leg."] Legs, or pillars, of the cerebrum. Crypt. [From the Gr. krypto, to "hide."] A secreting cavity; a follicle or glandular cavity. Cuneiform. [From the Lat. cuneus, a "wedge," and forma, "shape."] Having the shape or form of a wedge. Name given to two carpal and six tarsal bones. Cu'ticle. [From the dim. of Lat. cutis, the "skin."] A term applied to the upper, or epidermal, layer of the skin. Cu'tis Vera. [Lat.] The true skin; that underneath the epidermal layer. Cys'tic. [From the Gr. kustis, the "bladder."] Pertaining to a cyst, - a bladder or sac. Cy'toplasm. [From the Gr. kiitos, a "cell," and plasso, to "form."] The name given by Kolliker to the contents of a cell; same as pro- toplasm. , Decid'uous. [From the Lat. deciduus, "that falls down."] Falling or liable to fall, especially after a definite period of time. Decussation. [From the Lat. decusso, decussatum, to "cross."] The crossing or running of one portion athwart another. Degluti'tion. [From the Lat. de, "down," and glutitio, "swallow."] The act or power of swallowing. Delimitations. The marking, fixing, or prescribing of limits or boundaries. GLOSSARY 395 Del'toid. Having a triangular shape; resembling the Greek letter A (delta). Den'drite. [From the-Gr. dendrites, "pertaining to a tree."] The name given to the branching processes of the neurone which begin to divide and subdivide as soon as they leave the nerve-cell. Denti'tion. [From the Lat. dentitio, "teething."] 1. The process of cutting teeth. 2. The time during which teeth are being cut. 3. The kind, number, and arrangement of teeth proper to any animal. Dex'trin. A soluble substance obtained from starch. Dex'trose. C6H12O6. A form of sugar found in honey, grapes, and other fruits. Diabe'tes Mel'litus. [From the Gr. dia, "through," baino, to "go," and meli, "honey."] Excessive flow of sugar-containing urine. Dial'ysis. [From the Gr. dialud, to "dissolve."] Separation of liquids by membranes. Diapede'sis. From the Gr. dia, "through," and pedao, to "leap," to "go."] Passing of the red blood-corpuscles through vessel walls without rupture: sweating of blood. Di'aphragm. [From the Gr. diaphrasso, to "divide in the middle by a partition."] The partition muscle dividing the cavity of the chest from that of the abdomen. Diarthro'sis. [From the Gr. dia, "through," as implying no impediment, and arthron, a "joint."] A freely movable articulation. Dias'tole. [From the Gr.diastello, to " dilate."] The dilation of the heart. Diath'esis. [From the Gr. dia, "through," and tithenai, to "place."] A congenital condition of the system which renders it peculiarly liable to some diseases. Dichot'omous. [From the Gr. dichotomos, "cutting in two."] Pertaining to or consisting of a pair or pairs. Divided into two. Diffusion. [From the Lat. diffundere, to "pour in different directions."] The gradual and spontaneous mixing of two fluids which are placed in contact one with the other. Diges'tion. [From the Lat. digestio, "arrangement."] The process of converting the food from the state in which it enters the mouth to that in which it can pass from the alimentary canal into the blood- vessels and lymphatics. Diox'ide. [From the Gr. dis, "twice," and "oxide."] A compound com taining two atoms of oxygen. 396 GLOSSARY Dip'loe. [From the Gr. diplod, to "double," to "fold."] The osseous tissue between the tables of the skull. Dis'cus Prolig'erus, or germ disk. A term applied to a mass of cells clinging to the ovum when it is set free from the ovary. More recent term is "ovarian mound." Distilla'tion. [From the Lat. distillatio, a "dripping down."] The act of distilling or of falling in drops; a producing or shedding in drops. Dor'sal. [From the Lat. dorsum, the "back."] Pertaining to the back, or posterior part, of an organ. Duc'tus Arterio'sus. [Lat.] Arterial duct. Duc'tus Veno'sus. [Lat.] Venous duct. Duode'num. [From the Lat. duodeni, "twelve by twelve."] First part of small intestines, so called because about twelve fingers' breadth in length. Du'ra Ma'ter. [Lat.] The "hard mother," called dura because of its great resistance, and mater because it is the guardian or protector of the brain. The outer membrane of the brain and spinal cord. Dyspnce'a. [From the Gr. dys, "difficult," and pneo, to "breathe."] Difficult breathing. Ectop'ic. [From the Gr. ek, "out of," and topos, "place."] Characterized by being out of place. Ec'toderm. [From the Gr. ektos, "outside," and derma, the "skin."] The completed outer layer of cells, or outer blastodermic membrane. Same as epiblast. Ef'ferent. [From the Lat. ex, "out," and fero, to "carry."] Bear- ing or carrying outwards, as from the centre to the periphery. Elementary. Pertaining to or of the nature of an element or elements. (See Elements in Preliminary Chapter.) Elimination. [From the Lat. e, "out of," and limen, liminis, a "thres- hold."] The act of expelling waste matters. Eliminate signifies, literally, to throw out of doors. Em'bryo. The ovum and product of conception up to the fourth month, when it becomes known as the foetus. Emul'sion. [From the Lat. emulgere, to "milk."] A mixture of liquids, insoluble in one another, where one is suspended in the other in the form of minute globules, as the fat (butter) in milk. Enarthro'sis. [From the Gr. en, "in," and arthron, a "joint."] An GLOSSARY 397 articulation in which the head of one bone is received into the cavity of another, and can be moved in all directions. Endocar'dium. [From the Gr. endon, "within," and kardia, "heart."] Lining of the heart. En'dolymph. [From the Gr. endon, "within," and Lat. lympha, "water."] The fluid in the membranous labyrinth of the ear. Endos'teum. [From the Gr. endon, "within," and osteon, a "bone."] The lining membrane of the medullary cavity of a bone; the internal periosteum. Endothe'lium. [From the Gr. endon, "within," and thele, the "nipple."] A term applied to single layers of flattened transparent cells, applied to each other at their edges and lining certain surfaces and cavities of the body. In contradistinction to epithelium. En'siform. [From the Lat. ensis, a "sword," and forma, "form."] Shaped like a sword. En'toderm. [From the Gr. endon, "within," and derma, the "skin."] The completed inner layer of cells, or inner blastodermic membrane. Opposed to ectoderm. Same as hypoblast. En'zyme, or Enzy'ma. [From the Gr. en, "in," and sume, "leaven."] A term applied to a class of ferments. Ep'iblast. [From the Gr. epi, "upon," and blastos, a "germ," or "sprout."] The external, or upper, layer of the germinal membrane. Epicra'nial. [From the Gr. epi, "upon," and kranion, "the cranium."] That which is upon the cranium or scalp. Epider'mis. [From the Gr. epi, "upon," and derma, the "skin."] The outer layer of the skin. Epigas'tric. [From the Gr. epi, "upon," and gaster, "stomach."] Lying upon, distributed over, or pertaining to the abdomen or the stomach. Epiglot'tis. [From the Gr. epi, "upon," and glottis, the "glottis."] The cartilage at the root of the tongue which forms a lid or cover for the aperture of the larynx. Epimys'ium. [From the Gr. epi, "upon," and mus, "muscle."] The sheath of connective tissue surrounding an entire muscle. Epistro'pheus. [From the Gr. epi, "upon," and strephein, "turn."] The second cervical or odontoid vertebra; the axis; so-called because the atlas turns upon it. Epithe'lial. [From the Gr. epi, "upon," and thele, the "nipple."] Per- taining to the epithelium, the cuticle covering the nipple, or any 398 GLOSSARY mucous membrane. The term epithelium is now applied to the tissue composed of cells covering or lining all surfaces of the body. Erector. See Arrector. Eryth'rocytes. [From the Gr. eruthros, "red," and kutos, a "cell."] A fully developed red blood-corpuscle. Eth/moid. [From the Gr. ethmos, a "sieve," and eidos, "form," "re- semblance."] Sieve-like. A bone of the cranium, part of which is pierced by a number of holes. Eusta'chian Tube. A tube extending from the pharynx to the cavity of the middle ear, first described by Eustachius. Excre'tion. [From the Lat. excer'no, to "separate."] The separation from the blood of the waste particles of the body; also the materials excreted. Expira'tion. [From the Lat. expi'ro, to "breathe out."] The act of forcing air out of the lungs. Fal'ciform. [From the Lat. falx, a " sickle," and forma, " shape."] Sickle- shaped. Fallo'pian. A term applied to tubes and ligaments first pointed out by the anatomist Fallopius. See Uterine Tubes. Fas'cia, pl. Fas'ciae. [Lat.] A bandage, that which binds; a mem- branous, fibrous covering. Fascic'ulus. [Lat. a bundle.] A bundle of close-set fibres. Plural, fasciculi. Fau'ces. [Lat., pl. of faux, faucis, the "throat."] The cavity at the back of the mouth from which the larynx and pharynx proceed. Fecunda'tion. [From the Lat. fecundatio, "impregnation."] The act of making fruitful or prolific. Impregnation. Fem'oral. Pertaining to the femur. Fe'mur. [Lat.] The thigh. Fenes'tra. [Lat.] A window. FibrilTa, pl. Fibril'lse. [Dim. of Lat. fibra, a "fibre."] A little fibre. Fibrin'ogen. A proteid in blood plasma, main constituent of fibrin. Fi'brous. [From the Lat. fibra, "fibre."] Containing or consisting of fibres. Having the character of fibres. Fib'ula. [Lat. a "clasp."] The long splinter bone of the leg. Fil'iform. [From the Lat. filum, a "thread," and forma, "form."] Thread-like. Fim'brise. [Lat. "threads," a "fringe."] A border, or fringe. GLOSSARY 399 Fim'briated. Fringed. Fis'sion. [From the Lat. findo, fissum, to " cleave."] A cleaving, or breaking, up into two parts. Foe'tus. The child in utero from the fifth month of pregnancy till birth. Fol'licle. [From the dim. of Lat. follis, a "bag."] A little bag; a small gland. Fontanelle'. [Fr.] A little fountain. A term applied to the mem- branous spaces between the cranial bones in the new-born infant, in which the pulsation of the blood in the cranial arteries was im- agined to rise and fall like the water in a fountain. Fora'men, pl. Foram'ina. [Lat.] An opening, hole, or aperture. Fora'men Mag'num. [Lat.] A large opening. The large opening in the occipital bone. Fora'men Ova'le. [Lat.] An oval opening. Fos'sa, pl. Fos'sae. [From the Lat. fodio, fossum, to "dig."] A depres- sion, or sinus; literally, a ditch. Fo'vea Centra'lis. [Lat.] Central depression of the macula lutea. The point of most acute vision. Fun'dus. [Lat.] The base, or bottom, of any organ which has an external opening. Fun'giform. [From the Lat. fungus, a "mushroom," and forma, "form."] Having the shape of a mushroom. Funic'ulus, pl. Funiculi. [Dim. of Lat. funis, a "rope."] A little cord, or bundle, of aggregated fibres. Fu'siform. [From the Lat. fusus, a "spindle," and forma, "form."] Spindle-shaped. Gang'lia, pl. of Gang'lion. [From the Gr. gagglion, a "knot."] A knot- like arrangement of nervous matter in the course of a nerve. Gas'tric. [From the Gr. gaster, the "stomach."] Pertaining to the stomach. Gastrocne'mius. [From the Gr. gaster, the "belly," and kneme, the "leg."] The 5eZZy-shaped muscle of the leg. Gas'tro-pul'monary. Same as gastro-pneumonic. [From the Gr. gaster, "stomach," and pneumon, a "lung."] Pertaining to the stomach and the lungs: applied to the continuous mucous membrane of the respiratory and digestive tracts. Gen'erative. [From the Lat. gener are, to "beget."] Pertaining to genera- tion, or propagation. Connected with or resulting from the process of begetting. 400 GLOSSARY Genioglos'sus. [From the Gr. geneion, the "chin," and glossa, the "tongue."] A muscle connected with the chin and tongue. Genitals. [From the Lat. genitalis, "of or belonging to generation."] Pertaining to the organs of generation. Genito-u'rinary. Pertaining to both genital and urinary organs. Gesta'tion. [FromtheLat. gesture, "carry, bear."] The act or condition of carrying young in the womb from conception to delivery. Preg- nancy. Ging'lymus. [From the Gr. gigglymos, a "hinge."] A hinge-joint. Gladi'olus. [Dim. of Lat. gladius, a "sword."] The middle piece of the sternum. Glair'y. [From the Lat. clarus, "clear"; Fr. cZafr.] Like the clear white part of an egg. Gland. [From the Lat. glans, an "acorn."] A secreting organ. An organ that abstracts certain materials from the blood and makes of them a new substance. Gle'noid. [From the Gr. glene, a "cavity," and eidos, "form," "resem- blance."] A name given to a shallow cavity. Glomer'ulus. [Dim. of Lat. glomus, a "clew of thread," or "ball."] A botanical term signifying a small, dense, roundish cluster: a term applied to the ball-like tuft of vessels in capsules of the kidneys. Glos'so-pharynge'al. [From the Gr. glossa, the "tongue, ''and pharygx, the "pharynx."] Belonging to the tongue and pharynx. Glot'tis. [Gr. the "mouthpiece of a flute."] The aperture of the larynx. Glute'i, pl. of Glute'us. [From the Gr. gloutoi, the "buttocks."] The muscles forming the buttocks. Gly'cogen. Literally, producing glucose. Animal starch found in liver, which may be changed into glucose. GlycosuAia. [From the Gr. glukus, "sweet," and ouron, "urine."] A condition in which sugar is present in the urine. Graaf'ian Fol'Iicles, or Ves'icles. A term applied to the hollow bodies in the ovaries, containing the ova. More recent term is "vesicular follicles." Gramme. [From the Gr. gramma.] Unit of weight of the metric system. It is equivalent to 15.43 grains Troy. Gus'tatory. [From the Lat. gusto, gustatum, to "taste."] Belonging to the sense of taste. GLOSSARY 401 Haemoglo'bin. [From the Gr. haima, " blood," and Lat. globus, a " globe," or "globule.") A complex substance which forms the principal part of the blood-globules, or red corpuscles of the blood. Hsamorrhoi'dal. [From the Gr. haima, "blood," and rheb, to "flow."] Pertaining to haemorrhoids, small tumours of the rectum, which frequently bleed. Haver'sian Canals. Canals in the bone, so called from their discoverer, Dr. Clopton Havers. Hemophilia. [From the Gr. haima, "blood," and philein, "to love."] A congenital, morbid condition, characterized by a tendency to bleed immoderately from any insignificant wound, or even spontaneously. Hepat'ic. [From the Gr. hepar, hepatos, the "liver. "] Pertaining to the liver. Hi'lum, sometimes written Hi'lus. [Lat.] It is the depression (usually on concave side) of a gland, where vessels, nerves, and ducts enter or leave. Histol'ogy. [From the Gr. histos, a "web, tissue," and logos, "word.") That branch of anatomy which is concerned with the structure, especially the microscopic structure, of the tissues of the body. Homoge'neous. [From the Gr. homos, "the same," and genos, "kind."] Of the same kind or quality throughout; uniform in nature, -the reverse of heterogeneous. Hu'merus. [Lat. the "shoulder."] The arm-bone which concurs in form- ing the shoulder. Hy'aline. [From the Gr. hyalos, "glass."] GZuss-like, resembling glass in transparency. Hy'aloid. [From the Gr. hyalos, "glass,''and eidos, "form."] The name given the membrane which encloses the vitreous humour of the eye. ■It invests the vitreous humour except in front, where it is continuous with the suspensory ligament of the crystalline lens. Hy'drogen. An elementary gaseous substance, which in combination with oxygen produces water, H2O. Hy'oid. [From the Gr. letter upsilon, v, and eidos, "form," "resem- blance."] The bone at the root of the tongue, shaped like the Greek- letter upsilon, v. Hypermetro'pia. [From the Gr. hyper, "over," "beyond," metron, "measure," and bps, the "eye."] Far-sightedness. Hyperpnce'a. [From the Gr. hyper, "over," and pneb, to "breathe."] Energetic or laboured respiration. 402 GLOSSARY Hyper'trophy. [From the Gr. hyper, "over," and trophe, "nourishment."] Excessive growth; thickening or enlargement of any part or organ. Hy'poblast. [From the Gr. hypo, "under" and blastos, a "sprout," or "germ."] The internal, or under, layer of the germinal membrane. Hypochon'driac. [From the Gr. hypo, "under," and chondros, a "carti- lage."] A term applied to the region of the abdomen und^r the car- tilages of the false ribs. Hypogastric. [From the Gr. ''hypo, "under," and gaster, "stomach."] Situated below the stomach. Pertaining to the hypogastrium. Hypoglos'sal. [From the Gr. hypo, "under," and glbssa, the "tongue."] A name given to the motor nerve of the tongue. Hypoph'ysis. [From the Gr. phusis, a "growing."] The pituitary body of the brain which is lodged in the central depression of the sphenoid bone. Il'eum. [From the Gr. eileo, to "twist."] The longest twisting portion of the small intestine. Il'iac. Pertaining to the ilium. Il'ium, pl. Il'ia. [From the Gr. ilium, a "citadel."] The upper part of the os innominatum; the haunch-bone; so called because the crest of the bone forms a rampart, as it were, to the pelvis. IncPsor. [From the Lat. inci'so, to " cut."] Applied to the front teeth of both jaws, which have sharp cutting edges. In'cus. [Lat.] An anvil; the name of one of the bones of the middle ear. Inflammation. [From the Lat. inflammatio, a "setting on fire."] A morbid condition characterized by pain, heat, redness, swelling, and usually loss of function. Infundib'ula. [Lat. pl. of infundibulum, a "funnel."] Funnel-shaped canals. In'guinal. [From the Lat. inguen, inguinis, the "groin."] Pertaining to the groin. Inhibition. [From the Lat. inhibere, "restrain."] The lowering of the action of a nervous mechanism by nervous impulses reaching it from a connected mechanism. Inos'culate. [From the Lat. in, "into," and osculum, a "little mouth."] To unite, to open into each other. Insalivation. The process of mixing the saliva with the food in the act of mastication. GLOSSARY 403 In'sulate. [From the Lat. insula, an "island."] To isolate or separate from surroundings. Integ'ument. [From the Lat. in, and te'go, to "cover."] The skin, or outer covering of the body. Innominate. [From the Lat. innominatus, "nameless."] A name given an artery, vein, and a bone. Intercellular. Lying between cells. Intercostal. [From the Lat. inter, "between," and costa, "rib."] Situ- ated or intervening between successive ribs of the same side of the body. Interlob'ular. That which lies between the lobules of any organ. Interstice. [Fromthe Lat. inter, "between," and sto, or sisto, to "stand."] The space which stands between things; any space or interval between parts or organs. Interstitial. Pertaining to or containing interstices. Intestine. [From the Lat. in'tus, "within."] The part of the alimentary canal which is continuous with the lower end of the stomach; also called the intestines, or the bowels. Intralob'ular. That which lies within the lobules of any organ. I'ris. [Lat. the "rainbow."] The coloured membrane suspended be- hind the cornea of the eye. It receives its name from the variety of its colours. Is'chium. [From the Gr. ischio, to "support."] The lower portion of the os innominatum; that upon which the body is supported in a sitting posture. Jeju'num. [From the Lat. jejunus, "fasting," "empty."] The part of the small intestine comprised between the duodenum and ileum. It has been so called because it is almost always found empty after death. Ju'gular. [From the Lat. jugulum, the "throat."] Pertaining to the throat. Katabol'ic. [From the Gr. kataballb, to "throw down."] Pertaining to katabolism, the process by means of which the more complex elements are rendered more simple and less complex. The opposite of anab- olism. Lac'rimal. [From the Lat. lacrima, "tear."] Of or pertaining to tears. Lacta'tion. [From the Lat. lac, lactis, "milk."] The period of giving milk. 404 GLOSSARY Lac'teal. A term applied to the lymphatic vessels in the intestines which absorb the milk-Xike fluid, the chyle, from the intestines. Lac'tic Acid. An acid obtained from sour milk. Lactiferous. [From the Lat. lac, "milk, " and ferre, "bear."] Bearing, or conveying, milk, as a lactiferous duct. Lacu'na, pl. Lacu'nae. [Lat. a "cavity," an "opening."] A little hollow space. Lambdoi'dal. [From the Gr. letter A (Lambda'), and eidos, "form," "resemblance."] Resembling the Gr. letter A. Lamel'la, pl. Lamel'lae. [Lat.] A thin plate, or layer. Lar'ynx. The upper part of the air-passage, between the trachea and the base of the tongue. Laryn'goscope. [From the Gr. larygx, the "larynx," and skopeo, to "look at."] The instrument by which the larynx may be examined in the living subject. Latis'simus Dor'si. [Lat. superlative of latus, "broad," "wide," and dorsum, the "back."] The widest muscle of the back. Lec'ithin [From the Gr. lekithos, the "yellow of egg."] A complex, fatty substance found in the brain and elsewhere; in the yolk of eggs. It contains phosphorus. Leu'cocyte. [From the Gr. leukos, "white," and kutos, a "cell."] A term used to denote the white, or pale corpuscles, in the blood and lymph. Lig'ament. [From the Lat. ligo, ligatum, to "bind."] Anything that binds, or unites. Lin'ea Alba. [Lat.] The white line formed by the crossing of the aponeu rotic fibres in the middle line of the abdomen. Lin'ea Ilio-pectine'a. [Lat.] A line forming the brim of the pelvis, so named from the subjacent bones, ilium and pecten (pubic bone). Litre. [From the Gr. litra.'] The unit of the measure of capacity of the Metric System. It is equivalent to 33.81 fluid ounces, United States pharmacopoeia, and 35.196 imperial fluid ounces, British pharma- copoeia. Lob'ule. [From the dim. of Lat. lobus, a "lobe."] A small lobe. Lum'bar. [From the Lat. lumbus, the "loin."] Pertaining to the loins. Lymph. [From the Lat. lympha, "water."] A colourless fluid, resem- bling water in appearance. Lymphat'ic. Pertaining to lymph; a vessel, or tube, containing lymph. GLOSSARY 405 Lymph'ocyte. [From the Lat. lympha, "water" and Gr. kutos, "a cell."] Name given to recently formed white blood-corpuscles that later become leucocytes. Lymph'oid. [From the Lat. lympha, "water," and Gr. eidos, "form," "resemblance."] Having resemblance to lymph. Mac'ula Lute'a. [Lat.] Yellow spot. Ma'lar. [From the Lat. mala, the "cheek."] Pertaining to the cheek. Malle'olus, pl. Malle'oli. [Dim. of Lat. malleus, a "hammer."] A name given to the pointed projections formed by the bones of the leg at the ankle-joint. Mal'tose. A sugar which forms hard white crystals, is directly fermented by yeast, and is closely like dextrose in its properties. C12H22OU + H2O. Malpig'hian Bod'ies. [So called in honor of Malpighi, a celebrated Italian anatomist.] A term applied to small bodies, or corpuscles, found in the kidney and spleen. Mamm'ary. [From the Lat. mamma, " the breast."] Of or pertain- ing to the breast. Man'dible. [From the Lat. mandere, " chew," " masticate."] The under jaw, or inferior maxillary, as distinguished from the upper jaw, or superior maxillary. Manu'brium. [Lat. a "haft," a "handle."] Name given to the upper portion of the breast bone. Mas'seter. [From the Gr. massaomai, to "chew."] One of the muscles of mastication. Mas'toid. [From the Gr. mastos, the "breast," and eidos, "form," "re- semblance."] Shaped like the breast. Ma'trix. [Lat.] The womb. Producing or containing substance. Max'illary. [From the Lat. maxilla, a "jaw."] Pertaining to the max- illae, or jaws. Mea'tus. [From the Lat. meo, meatum, to "pass.'] A passage, or canal. Mediasti'nal. [From the Lat. medius, "middle."] Of or pertaining to a mediastinum or middle septum or partition. The interval in the middle of the chest between the pleurae of the two sides. Medul'la Oblonga'ta. [Lat.] The "oblong marrow"; that portion of the brain which lies within the skull, upon the basilar process of the occipital bone. Meibo'mian. A term applied to the small glands between the conjunctiva 406 GLOSSARY and tarsal cartilages, discovered by Meibomius. More recent term is Tarsal glands. Mem'brane. [From the Gr. membrane, "parchment."] An enveloping or a lining tissue of the body. Menin'ges. [From the pl. of Gr. menigx, "membrane."] Plural of meninx. Term applied to the three membranes that invest the brain and spinal cord. Menis'ci. [Sing. Meniscus.] [From the Gr. meniskos, a "crescent."] Concavo-convex disks. Men'opause. [From the Gr. men, "month," and pausis, a "checking."] The final cessation of the menses. The end of menstruation. Menstruation. [From the Lat. menstruare, "menstruate."] The act of menstruating or discharging the menses. Mes'entery. [From the Gr. mesos, "middle," and enteron, the "intestine."] A duplicature of the peritoneum covering the small intestine, which occupies the middle, or centre, of abdominal cavity. Mes'oblast. [From the Gr. mesos, "middle," and blastos, a "germ" or "sprout."] The middle layer of the germinal membrane. Mesoco'lon. A duplicature of the peritoneum covering the colon. Mes'oderm. [From the Gr. mesos, "middle," and derma, the "skin."] The middle germinal layer of cells lying between the ectoderm and entoderm. Same as mesoblast. Metab'olism. [From the Gr. metabole, "change."] The changes taking place in cells, whereby they become more complex and contain more force, or less complex and contain less force. The former is construc- tive metabolism, or anabolism; the latter, destructive metabolism, or katabolism. Metacar'pus. [From the Gr. meta, "after, " or "beyond," and karpos, the "wrist."] The part of the hand comprised between the wrist and fingers. Metatar'sus. [From the Gr. meta, "after," or "beyond" and tarsos, the "instep."] That part of the foot comprised between the instep and toes. Metre. [From the Gr. metron, a "measure."] The primary unit of the Metric System. The measure of length from which the units of weight and capacity are derived. It is equivalent to 39.37 inches. A milli- metre is one-thousandth part of a metre. Mi'crocytes. [From the Gr.mikros, "small,''and kutos, a "cell."] A small cell, or corpuscle, found in the blood plasma. GLOSSARY 407 M.'tral. Resembling a mitre. Mo'lar. [From the Lat. mola, a "mill."] A term applied to the teeth, which bruise, or grind, the food. Molec'ular. Pertaining to molecules. Mol'ecule. [From the dim. of Lat. moles, a "mass."] The smallest quantity of any substance (either element or compound) which can exist in a free state. A molecule may be chemically separated into two or more atoms. Monox'ide. [From the Gr. monos, "single," and "oxide."] A compound containing one atom only of oxygen. Mo'tor Oc'uli. [Lat.] Mover of the eye. Moto'rial. That which causes movement. Mu'cin. The chief constituent of mucus. Mu'cous. A term applied to those tissues that secrete mucus. Mus'cle. [From the Gr. mus, "muscle."] A kind of animal tissue con- sisting of bundles of fibres whose essential physiological characteris- tic is contractility. Myocar'dium. [From the Gr. mus, muos, a "muscle," and kardia, the "heart."] The muscular structure of the heart. Myo'pia. [From the Gr. mud, to "contract," and dps, the "eye."] Near- sightedness. . Myosin. Chief proteid substance of muscle. Na'ris, pl. Na'res. [Lat.] A nostril. Neurax'on. [From the Gr. neuron, "nerve," and axon.] An axis cylinder process. See Axis Cylinder. Neurilem'ma. [From the Gr. neuron, a "nerve," and lemma, a "coat," or "covering."] Nerve-sheath. Neu'rone. [From the Gr. neuron, a "nerve."] The nerve-cell, inclusive of all its processes, nerve-fibre and nerve-endings. NFtrogen. A colourless gas forming nearly four-fifths of the atmosphere: the diluent of the oxygen in the air. Literally, that which generates nitre. Node. [From the Lat. nodus, a "knot."] A knot, or what resembles one. A lymphatic ganglion. Nucle'olus, pl. Nucle'oli. [Dim. of Lat. nucleus, a "kernel."] A smaller nucleus within the nucleus. Nu'cleus, pl. Nu'clei. [Lat. a "kernel."] A minute vesicle embedded in the cell protoplasm (cytoplasm). 408 GLOSSARY Nutri'tion. [From the Lat. nu'trio, to "nourish."] The processes bj which the nourishment of the body is accomplished. Occip'ital. [From the Lat. occiput, occipitis, the "back of the head."] Pertaining to the occiput, the back part of the head. Odon'toid. [From the Gr. odous, odontos, a "tooth," and eidos, "form," "resemblance."] Tooth-like. CEde'ma. [From the Gr. oideo, to "swell."] A swelling from effusion of serous fluid into the areolar tissue. CEsoph'agus. [Gr. oisophagos, from oid (fut.), oiso, to "carry," and phagein, "to eat."] The gullet. Olec'ranon. [From the Gr. diene, the "elbow," and kranon, the "head."] The head of the elbow. O'lein. [From the Lat. oleum, "oil."] One of the three chief constit- uents of fat. Oil (oleum) signifies, literally, juice of the olive (Lat. olea). Olfac'tory. [From the Lat. olfacio, olfactum, to "smell."] Belonging to the sense of smell. Omen'tum. [Lat. "entrails."] A duplicature of the peritoneum, with more or less fat interposed. Ophthal'mic. [From the Gr. ophthalmos, the "eye."] Belonging to the eye. Op'sonins. [From the Gr. opsonion, "provisions."] A name given to chemical substances found in blood plasma which make microbes more susceptible to phagocytes. Op'tic. [From the Gr. optbs, "visible."] That which relates to sight. O'ra Serra'ta. [Lat.] Serrated border. Orbicula'ris. [From dim. of Lat. orbis, an "orb," or "circle."] Name of the circular muscles. Or'bital. [From the Lat. orbita, a "track," "rut of a wheel."] Pertaining to the orbit, the bony cavity in which the eyeball is suspended. Organ. [From the Gr. organon, an "instrument, implement, tool."] Any part of the body with a special function. Os, pl. Ora. [Lat.] A mouth. Os, pl. Ossa. [Lat.] A bone. Os Cox'ae. The hip bone, or os innominatum. Osmo'sis. [From the Gr. bsmos, "impulsion."] Diffusion of liquids through membranes. Os'sa Innomina'ta, pl. of Os Innomina'tum. [Lat.] "Unnamed bones." GLOSSARY 409 The irregular bones of the pelvis, unnamed on account of their non- resemblance to any known object. Os'seous. [From the Lat. os, a "bone."] Consisting of or resembling bone. Os'sicle. [From the Lat. ossiculum, dim. of os, a "bone."] A small bone. Os'teoblasts. [From the Gr. osteon, a "bone," and blastos, a "germ," or "sprout."] The germinal cells deposited in the development of bone. Otoliths. [From the Gr. ous, otos, the "ear," and lithos, a "stone."] Particles of calcium carbonate and phosphate found in the internal ear. O'vum, pl. O'va. [Lat. an "egg."] The human germ-cell. Ovula'tion. The formation or production of ova; also the discharge of an ovum from an ovary. Oxida'tion. The action of oxidizing a body; that is, combining it with oxygen, the result of which combination is an oxide. Ox'ygen. A tasteless, odourless, colourless gas, forming part of the air, water, etc., and supporting life and combustion. Pal'ate. [From the Lat. pala'tum, the "palate."] The roof of the mouth, consisting of the hard and soft palate. Pal'mitin. One of the three chief constituents of fat. Pal'pebra, pl. Pal'pebrae. [Lat.] The eyelid. Pan'creas. A compound secreting gland; one of the accessory organs of nutrition. The sweetbread of animals. Papil'lae. [Lat. pl. of papilla, a "nipple," a "pimple."] Minute emi- nences on various surfaces of the body. Paraglob'ulin. A proteid substance of the blood plasma. Pari'etal. [From the Lat. paries, parietis, a "wall."] Pertaining to a wall. Parot'id. [From the Gr. para, "near," and ous, otos, the "ear."] The large salivary gland under the ear. Parturition. [From the Lat. parturio, parturitum, to "bring forth."] The act of bringing forth, of giving birth to young. Patel'la. [Lat. "a little dish."] A small, &owZ-shaped bone; the knee- pan. Pec'toral. [From the Lat. pectus, pectoris, the "breast."] Pertaining to the breast, or chest. 410 GLOSSARY Ped'icle. [From the dim. of Lat. pes, pedis, a "foot."] A stalk. Pedun'cle. [From the Lat. pedunculus, dim. of pes, a "stalk," a "foot."] A narrow part acting as a support. Pel'vic. [From the Lat. pelvis, a "basin."] Pertaining to the pelvis, the basin, or bony cavity, forming the lower part of the abdomen. Pep'sin. [From the Gr. pepto, to "digest."] A ferment found in gastric juice, having power to convert proteids into peptones. Pep'tone. [From the Gr. pepto, to "digest."] A term applied to proteid material digested by the action of the digestive juices. Pericar'dium. [From the Gr. peri, "about," "around," and kardia, the "heart."] The serous membrane covering the heart. Perichon'drium. [From the Gr. peri, "about," "around," and chondros, a "cartilage."] The serous membrane covering the cartilages. Per'ilymph. [From the Gr. peri, "about," "around," and the Lat. lympha, "water."] The fluid in the osseous, and surrounding the membranous labyrinth of the ear. Perimys'ium. [From the Gr. peri, "around," and mus, "muscle."] The connective tissue septa connecting and enveloping the separate fas- ciculi of a muscle. Perine'um. [From the Gr. perinaioni] The region of the body between the thighs, extending from the anus to the fourchette in the female, or to the scrotum in the male. Perios'teum. [From the Gr. peri, "about," "around," and osteon, a "bone."] The membrane covering the bones. Peripheral. [From the Gr. peri, "about," "around," and pherd, to "bear."] Pertaining to the periphery, or circumference; that which is away from the centre and towards the circumference. Peristal'sis. [From the Gr. peristellb, to "surround," to "compress."] Peristaltic action. A term applied to the peculiar movement of the intestines, like that of a worm in its progress, by which they gradually propel their contents. Perspira'tion. [From the Lat. perspi'ro, to "breathe through."] The sweat, or watery exhalation, of the skin; when visible, it is called sensible perspiration; when invisible, it is called insensible perspiration. Peritone'um. [From the Gr. periteind, to "stretch around," to "stretch all over."] The serous membrane lining the walls and covering the contents of the abdomen. Perone'al. [From the Gr. perone, the "fibula."] Pertaining to the fibula; a term applied to muscles, or vessels, in relation to the fibula. GLOSSARY 411 Pe'trous. [From the Gr. petra, a "rock."] Having the hardness of rock. Pey'er's Glands. The clustered glands in the intestines, so named after the anatomist, Peyer, who well described them. Phag'ocytes. [From the Gr. phagein, "eat," and kutos, a "cell."] A lymph-corpuscle, or white blood-corpuscle, regarded as an organism capable of devouring what it meets, especially pathogenic microbes. Phalan'ges. [Lat. pl. of phalanx, a "closely serried array of soldiers."] A name given to the small bones forming the fingers and toes, because placed alongside one another like a phalanx. Phar'ynx. [From the Gr. pharad, to "plough," to "cleave."]. The cleft, or cavity, forming the upper part of the gullet. Phren'ic. [From the Gr. phren, the "diaphragm."] Pertaining to the diaphragm. Pi'a Ma'ter. [From the Lat. pia (fem.), "tender," "delicate," and mater, "mother."] The most internal of the three membranes of the brain. See Dura Mater. Pig'ment. [From the Lat. pigmentum, "paint," "colour."] Colouring matter. Pin'na. [Lat. a "feather," or "wing."] External cartilaginous flap of the ear. Pi'siform. [From the Lat. pisum, a "pea," and forma, "form."] Having the form of a pea. One of the carpal bones. Pitu'itary. [From the Lat. pituitarius, an "herb that removes phlegm."] Secreting or containing mucus, or supposed to do so. (It was for- merly supposed that the secretions of the nose proceeded from the brain.) (See hypophysis and description of pituitary body in text.) Placen'ta. [Lat. a "thin, flat cake."] Aflat, circular, vascular substance which forms the organ of nutrition and excretion for the foetus in utero. Plan'tar. [From the Lat. planta, "the sole of the foot."] Pertaining to the sole of the foot. Plas'ma. [From the Gr. plassb, to "forip."] A tenacious, plastic fluid containing the coagulating portion of the blood; that in which the blood-corpuscles float; the liquor sanguinis. Platys'ma. [From theGr. platus, "broad."] A thin, broad muscle situated immediately beneath the skin at the side of the neck, and extending from the chest and shoulder to the face. Pleu'ra. [Gr. the "side."] A serous membrane divided into two portions, lining the right and left cavities, and reflected over each lung. 412 GLOSSARY Plex'us. [From the Lat. plecto, plezum, to "knit," or "weave."] A net* work of nerves or veins. Pneumogas'tric. [From the Gr. pneumon, a "lung," and gaster, the "stomach."] Pertaining to the lungs and stomach. Polyhe'dral. [From the Gr. polys, "many," and hedra, a "base," a "side."] Many-sided. Pons Varo'lii. [Lat.] "Bridge of Varolius." The white fibres which form a bridge connecting the different parts of the brain, first de- scribed by Varolius. Poplite'aL [From the Lat. poples, poplitis, the "ham," the "back part of the knee."] The space behind the knee-joint is called the popliteal space. Premo'lar. [From the Lat. prce, "before," and molaris, "moiar."] An- terior in position to a molar; as premolar tooth. Prismat'ic. Resembling a prism, which, in optics, is a solid, triangular- shaped glass body. Prona'tion. [From the Lat. pronus, "inclined forwards."] The turning of the hand with the palm downwards. Prona'tor. The group of muscles which turn the hand palm downwards. Pro'teids. A general term for the albuminoid constituents of the body. Pro'toplasm. [From the Gr. protos, "first," and plassb, to "form."] A first-formed, organized substance; primitive organic cell matter. Pseudosto'mata. [From the Gr. pseudes, "false," and stoma, stomatos, a "mouth."] False openings. Pso'as. [From the Gr. psoa, "loin."] A muscle of the loins and pelvis. The tenderloin. Pter'ygoid. [From the Gr. pteron, a "wing," and eidos, "form," "re- semblance."] Wing-like. Pty'alin. [From the Gr. ptyalon, "saliva."] A ferment principle in saliva, having power to convert starch into sugar. Pu'berty. [From the Lat. puber, "adult."] The age at which repro- duction becomes possible; sexual maturity in the human race. Pu'bes, gen. Pu'bis. [Lat.] The hairy region above the genitals, also used for os pubis, the portion of the os innominatum forming the front of the pelvis. Pul'monary. [From the Lat. pulmo, pl. pulmones, the "lungs."] Re- lating to the lungs. Pulse. [From the Lat. pel'lo, pul'sum, to "beat."] The striking of an artery against the finger, occasioned by the contraction of the heart, commonly felt at the wrist. GLOSSARY 413 Pylor'ic. Pertaining to the pylorus. Pylo'rus. [From the Gr. pyle, a "gate," or "entrance," and ouros, a "guard."] The lower orifice of the stomach, furnished with a circular valve which closes during stomach digestion. Pyrex'ia. [From the Gr. pyresso, (fut.) pyrexo, to "have a fever."] Ele- vation of temperature; fever. Quad'riceps. [From the Lat. quatuor, "four," and caput, the "head."] A term applied to the extensor muscle of the leg, having four heads, or parts. Quad'rate. [From the Lat. quadratus, "make four-cornered, or square."] Square. (A small lobe of the liver.) Ra'dius. [Lat. a "rod," the "spoke of a wheel."] The outer bone of the forearm, so called from its shape. Rale. [From the Fr. raler, to "rattle in the throat."] A rattling, bub- bling sound attending the circulation of air in the lungs. Different from the murmur produced in health. Rec'tus. [Lat.] Straight. Re'nal. [From the Lat. ren, renis, the "kidneys."] Pertaining to the kidneys. Ren'nin. [Rennet.] The milk-curdling enzyme which constitutes the active principle of rennet. Resiliency. [From the Lat. re, "back," and silere, to "leap."] The act of resiling, leaping, or springing back; the act of rebounding. Respiration. [From the Lat. res'piro, to "breathe frequently."] The function of breathing, comprising two acts; inspiration, or breath- ing in, and expiration, or breathing out. Res'tiform. [From the Lat. restis, a "cord, rope," and forma, "form."] In anatomy denoting a part of the medulla oblongata, called the restiform body. Retic'ular. [From the Lat. reticulum, a "small net."] Resembling a small net. Ret'iform. [From the Lat. rete, a "net," and forma, "form."] Having the form, or structure, of a net. Ret'ina. [From the Lat. rete, a "net."] The most internal membrane of the eye; the expansion of the optic nerve. Ri'ma Glotti'dis. [Lat. rima, a "chink," or "cleft."] The opening of the glottis. 414 GLOSSARY Ru'gae. [Lat. pl. of ruga, a "wrinkle."] A term applied to the folds, or wrinkles, in the mucous membrane, especially of the stomach and vagina. Sa'crum. [Lat., neut. of sacer, "sacred."] The large triangular bone above the coccyx, so named because it was supposed to protect the organs contained in the pelvis, which were offered in sacrifice and considered sacred. Sag'ittal. [From the Lat. sagitta, an "arrow."] Arrow-shaped. Sal'ivary. Pertaining to the saliva, the fluid secreted by the glands of the mouth. Saphe'nous. [From the Gr. saphes, "manifest."] A name given to the two large superficial veins of the lower limbs. Saponification. [From the Lat. sapo, saponis, "soap," and facio, to "make."] Conversion into soap. Sarcolem'ma. [From the Gr. sarx, sarkos, "flesh," and lemma, a "cover- ing."] The covering of the individual muscle-fibrils. Sar'cous. [From the Gr. sarx, sarkos, "flesh."] Fleshy, belonging to flesh. Sarto'rius. [From the Lat. sartor, a "tailor."] The name of the muscle used in crossing the legs, as a tailor does when he sits and sews. Scap'ula. [Lat.] The shoulder-blade. Scaph'oid. [From the Gr. skaphe, a "boat," and eidos, "form."] Boat- shaped. The bone on the radial side of the proximal row of the carpus. Also called navicular. Scle'ra. [Lat. scleroticus, from Gr. sklerob, to "harden."] Hard, tough. Seba'ceous. A term applied to glands secreting sebum. Se'bum, or Se'vum. [Lat. sevum, "suet."] A fatty secretion resembling suet, which lubricates the surface of the skin. Secre'tion. [From the Lat. secer'no, secre'tum, to "separate."] The process of separating from the blood some essential, important fluid; which fluid is also called a secretion. Semilu'nar. [From the Lat. semis, "half," and luna, the "moon."] Having the shape of a half-moon. Se'rous. Having the nature of serum. Se'rum. [Lat.] The watery fluid separated from the blood after coagu- lation. Ses,amoid. [From the Gr. sesamon, a "seed of the sesamum," and eidos, "form," "resemblance."] Resembling a grain of sesamum. GLOSSARY" 415 A term applied to the small bones situate in the substance of ten- dons, near certain joints. Sig'moid. [From the Gr. letter 2, sigma, and eidos, "form," "resem- blance."] Curved like the letter 8. Sole'us. [From the Lat. solea, a "sandal."] A name given to a muscle shaped like the sole of a shoe. Specific Grav'ity. The comparative density or gravity of one body con- sidered in relation to another assumed as the standard. In measur- ing the specific gravity of liquids or solids, water is usually taken as the standard of comparison, being reckoned as a unit. Sphe'noid. [From the Gr. sphen, a "wedge," and eidos, "form," "re- semblance."] Like a wedge. Spermat'ic. [From the Gr. sperma, "seed."] Of or pertaining to sperm, or male seed, the spermatic cord. Sphincter. [From the Gr. sphiggo, to "bind tight," to "close."] A circular muscle which contracts the aperture to which it is attached. Spige'lian. One of the lobes of the liver. Squa'mous. [From the Lat. squama, a "scale."] Sccde-like. Sta'sis. [From the Gr. stab, to "stop."] Stagnation of the blood . current. Steap'sin. A ferment of the pancreatic secretion which to some extent resolves fat into fatty acids and glycerine. Ste'arin. One of the three chief constituents of fat. Ster'num. [Lat.] The breast bone. Stim'ulus, pl. Stim'uli. [Lat. a "goad."] Anything that excites to action. Sto'ma, pl. Sto'mata. [From the Gr. stoma, stomatos, a "mouth."] A mouth; a small opening. Stom'ach. [From the Lat. stomachus, the "throat," "gullet," also the "stomach."] A more or less sac-like part of the body where food is digested. Strat'ified. [From the Lat. stratum, a "layer," and facio, to "make."] Formed or composed of strata, or layers. Stri'ated. [From the Lat. strio, striatum, to "make furrows."] That which has strice, furrows or lines. Stro'ma. [From the Gr. stroma, a "bed."] The foundation, or bed, tissue of an organ. Styloglos'sus. [From the Gr. stylos, a "pillar," and glbssa, the "tongue."] 416 GLOSSARY A muscle connected with a pointed style-like process of the temporal bone and the tongue. Subcla'vian. Under the clavicle. Subcuta'neous. [From the Lat. sub, "under," and cutis, the "skin."] Under the skin. Subling'ual. [From the Lat. sub, "under," and lingua, "tongue."] Situated under the tongue or on the under side of the tongue. Submax'illary. [From the Lat. sub, "under," and mala, "jaw."] The submaxillary gland, so called because it lies beneath the jaw. Suc'cus enter'icus. [From the Lat. succus, "juice, moisture," and enteron, "intestine."] Intestinal juice, secreted by the intestinal glands. Sudorif'erous. [From the Lat. sudor, "sweat," and fero, to "carry," to "bear."] A term applied to the glands secreting sweat. Sul'cus. [From the Lat. sulcus, a "furrow," "trench," "ditch," " wrinkle."] A fissure between two convolutions of the surface of the brain. Supina'tion. [From the Lat. supino, supinatum, to "bend backwards," to "place on the back."] The turning of the hand with the palm upwards. Su'pinators. The muscles which turn the hand with the palm upwards. Supra-re'nal. [From the Lat. super, " over," and ren, renis, the " kidney."] Above the kidney. Su'ture. [From the Lat. suo, sutum, to "sew together."] That which is sewn together, a seam; the seam uniting bones of the skull. Sym'physis. [From the Gr. syn, "together," and phyb, to "produce," to "grow."] A union of bones, usually of symmetrical bones in the median line, as the pubic bones and bones of the jaw. Synarthrosis. [From the Gr. syn, "together," and arthron, a "joint."] A form of articulation in which the bones are immovably joined together. Synchrondro'sis. [From the Gr. syn, "together," and chondros, "carti- lage."] Union by an intervening growth of cartilage. Syndesmo'sis. [From the Gr. syn, "together," and desmos, a "ligament."] Union by ligaments. Syno'via. [Supposed to be from the Gr. syn, "together," implying union or close resemblance, and bon, an "egg."] A fluid resembling the white of an egg. Syno'vial. Pertaining to synovia. Syn'tonin. [From the Gr. synteind, to "stretch," to "draw," referring GLOSSARY 417 to the peculiar property of muscular fibre.] A name given by Leh- mann to a substance obtained from muscular fibre by the action of dilute hydrochloric acid. Sys'tole. [From the Gr. systello, to "draw together/' to "contract."] The contraction of the heart. Tac'tile. [From the Lat. tac'tus, "touch."] Relating to the sense of touch. Tar'sus. [From the Gr. tar so s, the "instep."] The instep; also the cartilage of the eyelid. Tem'poral. [From the Lat. tem'pus, "time," and tem'pora, the "tem- ples."] Pertaining to the temples; the name of an*artery; so called because the hair begins to turn white with age in that portion of the scalp. Ten'don. [From the Lat. ten'do, to "stretch."] The white, fibrous cord, or band, by which a muscle is attached to a bone; a sinew. Ten'do Achil'lis. [Lat.] "Tendon of Achilles." The tendon attached to the heel, so named because Achilles is supposed to have been held by the heel when his mother dipped him in the river Styx to render him invulnerable. Thorac'ic. [From the Gr. thorax, a "breastplate," the "breast."] Per- taining to the thorax. Thy'roid. [From the Gr. thyreos, an "oblong shield," and eidos, "form," "resemblance."] Resembling a shield. A name given to an opening in the ossa innominata: to the piece of cartilage forming the anterior prominence of the larynx: to the gland placed in front of the larynx. Tib'ia. [Lat. a "flute," or "pipe."] The shin-bone, called tibia, from its fancied resemblance to a reed-pipe. Tibia'lis Anterior. [Lat.] The muscle situate at the anterior part of the tibia. Tis'sue. [From the Lat. texere, "weave."] An aggregate of similar cells and cell-products in a definite fabric. Tone. [Gr. tonos, from teind, to "stretch."] The state of tension proper to each tissue. A term used to express the normal excitability, strength, and activity of the various organs and functions of the body in a state of health. Also a distinct musical sound. Tonic'ity. The elasticity of living parts. A property of the muscles which is distinct from true irritability and determines the general tone of the tissues. 418 GLOSSARY Ton'sil. One of two prominent oval bodies situated in the recesses formed, one on each side of the fauces, between the anterior and posterior palatine arches. Trabec'ulae. [Lat. pl. of trabecula, a "little beam."] A term applied to prolongations of fibrous membranes which form septa, or partitions. Tra'chea. [Lat.] The windpipe. Transversa'lis. [Lat. from trans, "across," and verto, versum, to "turn, to "direct."] A term applied to a muscle which runs in a trans- verse direction. Trape'zius. [From the Gr. trapeza, "table."] A name given to the two upper superficial muscles of the back, because together they resemble a trapezium, or diamond-shaped quadrangle. Trapezoid'. [From the Gr. trapeza, "table," and eidos, "form."] One of the bones of the wrist. The second one of the distal row on the radial or thumb side. Tri'ceps. [From the Lat. tres, "three," and caput, the "head."] A term applied to a muscle having a triple origin, or three heads. Tricus'pid. [From the Lat. tres, "three,"and cuspis, cuspidis, a "point."] Having three points. TrochanTer. [From the Gr. trochad, to "turn," to "revolve."] Name given to two projections on the upper extremities of the femur, which give attachment to the rotator muscles of the thigh. Trochoi'des. [From the Gr. trachad, to "turn," to "revolve," and eidos, "form."] Rotating, or revolving. Applied to that kind of rotary arthrosis in which a part revolves to some extent upon another, as the atlas about the odontoid process of the atlas. Pivotal. Tryp'sin. The ferment principle in pancreatic juice which converts proteid material into peptones. Tuberos'ity. [From the Lat. tuber, tuberis, a "swelling."] A protuberance. Tu'bular. [From the Lat. tubulus, a "small pipe."] Having the form of a tube, or pipe. Tur'binated. [Lat. turbinatus, from turbo, hirbinis, a "top."] Formed like a top; a name given to the bones in the outer wall of the nasal fossae. Tym'panum. [From the Gr. tympanon, a "drum."] The drum, or hollow part, of the middle ear. Ul'na. [Lat. the "elbow."] The inner bone of the forearm, the olecranon process of which forms the elbow. GLOSSARY 419 UnCiform. [From the Lat. uncus, a "hook," and forma, "form."] Hooked, or crooked. One of the bones of the wrist, so called from its hook-like process. Umbil'icus. [Lat. the "navel."] A round cicatrix, or scar, in the me- dian line of the abdomen. U'rea. [From the Lat. urina, "urine."] Chief solid constituent of urine. Nitrogenous product of tissue decomposition. Ure'ter. [From the Gr. oured, to "pass urine."] The tube through which the urine is conveyed from the kidney to the bladder. Ure'thra. [From the Gr. oured, to "pass urine."] The canal through which the urine is conveyed from the bladder to the meatus urinarius. U'rine. [From the Lat. urina, "urine."] A waste fluid excreted by the kidneys holding in solution most of the nitrogenous and other soluble products of tissue-changes. Urinif'erous. [From the Lat. urina, "urine," and ferre, "bear."] Con- veying urine as uriniferous tubes, or ducts. U'terus. [From the Lat. uterus, "womb."] Womb. That part of the female generative apparatus in which the product of conception develops. U'vula. [Dim. of Lat. uva, a "grape."] The small, elongated, fleshy body hanging from the soft palate. Vag'inal. [From the Lat. vagina, a "sheath."] Sheath-like. Val'vulae Connivences. [Lat.] A name given to transverse folds of the mucous membrane in the small intestine. More recent term is " circular folds." Vas'a VasoCum. [Lat.] "The vessels of the vessels." The small blood- vessels which supply the walls of the larger blood-vesseZs with blood. Vas'cular. [From the Lat. vasculum, a "little vessel."] Relating to vessels; full of vessels. Va'so-constric'tor. [From the Lat. vas, a "vessel," and constringo, to "constrict."] An agent which brings about constriction of blood- vessels; specifically a nerve when stimulated, or a drug which acts in this way when administered. Va'so-dila'tor. [From the Lat. vas, a "vessel," and dilator, a "dilator."] An agent which brings about dilatation of blood-vesseZs. Ve'nae Ca'vae, pl. of Ve'na Ca'va. [Lat.] "Hollow veins." A name given to the two great veins of the body which convey the blood to the right auricle of the heart. 420 GLOSSARY Ve'nae Com'ites. [Lat.] ''Attendant veins." Veins which accompany the arteries. Ven'tral. [From the Lat. venter, ventris, the "belly."] Belonging to the belly cavity. Ven'tricle. [From the dim. of Lat. venter, the "belly."] A small cavity. Ver'miform. [From the Lat. vermis, a "worm," and forma, "form."] Worm-shaped. Ver'nix Caseo'sa. [Lat.] "Cheesy varnish." The fatty varnish found on the new-born infant, which is secreted by the sebaceous glands of the skin. VerTebrae, pl. of Ver'tebra. [Lat. from verto, to "turn."] The bones of the spine. Vil'li. [Lat. pl. of villus, "shaggy hair."] The conical projections on the valvula? conniventes, making the mucous membrane look shaggy. Vis'cera. [Lat. pl. of viscus.] The internal organs of the body. Vitel'line. [From the Lat. vitcllus, the "yolkof an egg."] A term applied to the yolk membrane. Vitel'lus. [Lat. from vita, "life."] The yolk of an egg. Vit'reous. [From the Lat. vitrum, "glass."] G7ass-like. A name applied to the transparent, jelly-like substance which fills the back part of the eyeball behind the crystalline lens. Vo'mer. [Lat. a "ploughshare."] The thin plate of bone shaped some- what like a ploughshare which separates the nostrils. Vul'va. The external female genitals. Xi'phoid. [From the Gr. xiphos, "sword" and eidos, "form."] Shaped like or resembling a sword. Ensiform. Zo'na Pellu'cida. [Lat.] "Pellucid zone." The broad, transparent ring which surrounds the yolk in the centre of the ovum. Zygomatdc. [From the Gr. zygos, "yoke," "join."] Of or pertaining to the malar bone or this bone and its connections. Constituting or entering into the formation of the zygoma. BIBLIOGRAPHY 421 BIBLIOGRAPHY Barker, Lewellys F., M.D., Anatomical Terminology (with special reference to the B. N. A.). Bernstein, Julius, The Five Senses of Man. Brubaker, Albert P., M.D., Text-book of Human Physiology. Chittenden, Russell H., Physiological Economy in Nutrition. Chittenden, Russell H., The Nutrition of Man. Collins, Howard D., M.D., and Rockwell, Wm. H., M.D., Physiology. Duncan, Robert Kennedy, The New Knowledge. Edgar, J. Clifton, M.D., The Practice of Obstetrics. Flint, Austin, M.D., Handbook of Physiology. Gerrish, Frederic Henry, M.D., Text-book of Anatomy. Gould, George M., M.D., Illustrated Dictionary of Medicine, Biology, and Allied Sciences. Halliburton, W. D., M.D., Essentials of Chemical Physiology. Howell, Wm. H., M.D., Text-book of Physiology. Hutchinson, Robert, M.D., Food and the Principle of Dietetics. Kirkes's Handbook of Physiology, Revised by Wm. H. Rockwell, M.D. and Chas. L. Dana, M.D. 422 BIBLIOGRAPHY Morris, Henry, and McMurrich, J. Playfair, M.D., Human Anatomy. Morrow, Albert S., M.D., Immediate Care of the Injured. Notter, J. Lane, and Firth, R. H., Theory and Practice of Hygiene. Ott, Isaac, M.D., Text-book of Physiology. Quain's Elements of Anatomy, Edited by E. A. Schafer and G. D. Thane. Remsen, Ira, Principles of Theoretical Chemistry. Roosa, D. B. St. John, M.D., and Davis, A. Edward, M.D., Handbook of Anatomy and Diseases of the Eye and Ear. Schafer, E. A., Essentials of Histology. Sobotta, Dr. Johannes, and McMurrich, J. Playfair, M.D., Atlas and Text-book of Human Anatomy. Spalteholz, Werner, Atlas of the Human Body. Spalteholz, Werner, Hand Atlas of Human Anatomy. Testut, Jean Leo, Human Anatomy. INDEX (And see Glossary, pages 387 to 420.) Abdomen, divisions of, 237. muscles of, 102. action of, 104. regions of, 237, 238. Abdominal, cavity, 19. salivary gland, 252, 266. Abducens nerve, 328. Abduction, 84. Absorption, 270, 273. paths of, 270, 273. Acetabulum, 72. Acid, definition of, 11. Acromegaly, 215. Acromion process, 68. Adam's apple, 220. Adduction, 84. Adductor muscles of thigh, 111. Adenoid tissue, 38. Adenology, definition of, 18. Adipose tissue, 37. Adjustment of eye, how accomplished, 359. Adrenal, arteries, 171. bodies, 215. Adrenalin, 215. Afferent neurones, 308. Ague cake, 213. Air, amount required, 230. composition of, 9. effect of respiration upon the, 229, 235. expired, 229, 230. inspired, 229, 230. Air-space, minimum amount of, 230. Albumin, 9. Albuminuria, 285. Alimentary canal, 236. divisions of, 237, 259. Alimentation, 272. Alkali, definition of, 12. Alkaline, earths, 12. metals, 12. Alveoli of lungs, 226. Amoeboid movement, 25, 138. Amphiarthroses, 81. Ampulla of semicircular canals, 349. Amylopsin, 267. Anabolism, 25, 275. Anastomosis of arteries, 161, 162. Anatomy, definition of, 15. divisions of, 18. Angiology, definition of, 18. Anhydride, definition of, 12. Animal starch, 7. Ankle, bones of, 71, 74. Annular ligaments, 128. Antrum, of bone, 50. of Highmore, 60. Anus, 251. Aorta, 164. abdominal, 165, 166, 169. arch of, 165, 166. ascending, 164, 166. descending, 165. thoracic, 164, 165, 169. Apnoea, 233. Aponeurosis, 36, 89. Apparatus, definition of, 26. Appendix, vermiform, 250. Aqueduct of Sylvius, 324. Aqueous humour, 358, 366. Arachnoid, 122, 318. Arborizations, end, 305. interepithelial, 306. Areola, 34. Areolar tissue, 34. Arm bone, 68. Artery, or arteries, 146, 160. adrenal, 171. anastomosis of, 161, 162. axillary, 167, 168. blood supply of, 157. brachial, 168. brachio-cephalic, 166. branches of, 162. bronchial, 169. carotid, common, 166. external, 166, 167. internal, 166, 167. cceliac axis, 169. contraction of, 188. distribution of, 161. dorsal, of foot, 175, 176. elasticity of, 188. extensibility of, 188. facial, 162. femoral, 174. 423 424 INDEX Artery, or arteries - continued. gastric, 169. hemorrhoidal, superior, 170. hepatic, 169, 258. hypogastric, 173. iliac, common, 173. external, 173, 174. internal, 173. innominate, 166. inosculation of, 162. intercostals, 169. lumbar, 173. mediastinal, 169. mesenteric, inferior, 170. superior, 170. nerve supply of, 157. oesophageal, 169. ovarian, 172. pericardial, 169. peroneal, 175. phrenic, 173. plantar, external, 175. internal, 175. plexus of, 162. popliteal, 174. pulmonary, 164. radial, 169. relaxation of, 188. renal, 171. sacral, middle, 173. severed, flow of blood from, 190, spermatic, 172. splenic, 170. structure of, 155. subclavian, 167. tibial, anterior, 174, 176. posterior, 174. tone of, 188, 191. ulnar, 169. uterine, 162. Arterial, tension, 190, 191. tone, 188, 191. Arterioles, 157. Arthrodia, 82. Articular cartilage, 40. Articulations, 79, and see Joints. Asphyxia, 232. Atom, definition of, 3. Atlas, 63. Auditory apparatus, 344. canals, 344. nerve, 328. Augmentation, 318. Auricle of ear, 344. Auricles of heart, 150. Automatic acts, 318. Axillary, artery, 167, 168. vein, 178. Axis, 64. Axis cylinder, 403. Axis cylinder process, 303, 304. Axon, 304. Azygos veins, 183. Back, muscles of, 96, 98. Bartholin, gland of, 377. Base, definition of, 12. Basic oxide, definition of, 12. Beet-sugar, 7. Biceps, of arm, 105. of thigh, 108. Bicuspid, teeth, 242. valve, 152. Bile, 133, 267. action of, upon food, 268. composition of, 268. duct, common, 258. ducts, 257, 261. pigments, 268. salts, 268. -secreting function of liver, 255. Bladder, 280, 287. Blastoderm, 27. layers of, 27. Blind spot, 357, 366. Blood, 134, 144. circulation of, 186, and see Circulation. clotting of, 141, and see Coagulation of blood. coagulability of, 142. composition of, 135, 144. defibrinated, 142. effect of respiration upon the, 231, 235. functions of, 135, 142, 144. haamoglobin, 136, 137. laked, 137. plasma, 135, 140, 145. -plates, 139, 144. properties, 134, 144. quantity, 134, 144. serum, 142. summary of, 144. Blood-corpuscles, 135, 144. blood-plates, 139, 144. red, 135, 144. function of, 137, 144. number of, 135. white, 137, 144. function, 139, 144. varieties, 138, 144. Blood-vessels, development of, 196. Blue baby, 195. Body, back view of, 17. cavities of, 19, 20, 22. composition of, 6. contents of, 19, 20, 22. front view of, 16, 18. structural units of, 23. structure of, 18, 22. Bodily heat, 296, 301. distribution of, 297. loss of, 297. production of, 297. regulation of, 298. Bone, or bones, 41. atlas, 63. axis, 64. INDEX 425 Bone, or bones - continued. blood supply of, 44. calcaneum, 74. canaliculi of, 44. cancellated, 42. classification of, 47. clavicle, 67. coccyx, 65. compact, 42, 44. composition of, 41. dense, 42. depressions of, 49, 50. digits, of foot, 77. of hand, 70. epistropheus, 64. ethmoid, 55. femur, 72. fibres of Sharpey, 44. fibula, 74. flat, 49. frontal, 53. functions of, 47, 48, 77. growth of, 44. Haversian canals, 44. system, 44. humerus, 68. hyoid, 60. ilium, 72. incus, 345, 346. inferior turbinated, 58. irregular, 49. ischium, 72. lacrimal, 57. lacunaj of, 44. lamellae of, 42. long, 49. lower jaw, 60. malar, 57. malleus, 345, 346. mandible, 60. marrow, 42. maxilla, 59. medullary canal of, 42. metatarsus, 76. nasal, 57. number of, 47. occipital, 52. of ankle, 71, 74. of arm, 67, 68. of calf, 74. of carpus, 69, 70. of cranium, 52. of ear, 78. of elbow, 69. of face, 57. of foot, 71, 75. of forearm, 67, 69. of hand, 70, 71. of head, 51. of heel, 74. of hip, 71. of leg, 71, 73. of lower extremities, 70. Bone, or bones - continued. of metacarpus, 70. of tarsus, 74. of thigh, 71, 72. of thorax, 65. of trunk, 61. of upper extremities, 66. of wrist, 69, 70. palate, 58. parietal, 53. patella, 73. pelvis, 77. periosteum, 44. phalanges, of foot, 77. of hand, 70. processes of, 49, 50. pubes, 72. radius, 69. regeneration of, 45. ribs, 66. sacrum, 65. scapula, 68. shin, 73. short, 49. sphenoid, 55. spongy, 42. stapes, 345, 346. sternum, 65. structure of, 41, 43. summary of, 46, 77. sutural, 57. table of, 78. temporal, 54. tibia, 73. ulna, 69. upper jaw, 59. uses of, 77. vertebra:, 62, 63. vomer, 57. Wormian, 57. Brachial, artery, 168. vein, 178. Brachio-cephalic artery, 166. vein, 177, 179. Brain, 318, 319, and see Cerebrum, as a whole, 325. divisions of, 319. function, localization of, 325. membranes of, 318. motor areas of, 325. sensory areas of, 325. size of, 326. sulci of, 323. summary, 334. ventricles of, 324. weight of, 326. Breast bone {and see Sternum), 65. Breasts, 377, 383. Broad ligaments of uterus, 374. Bronchi, 223, 234. Bronchial, arteries, 169. tubes, 223. Bronchioles, 223. 426 INDEX Brunner's glands, 249. Buccal cavity, 20, 239, 259. Buccinator, 93. Bursae, synovial, 123. Caecum, 250. Calcaneum, 74. Calcium phosphate, in body, 7. Calf bone, 74. Calorie, definition of, 14. Calyces of kidney, 277. Canalis cochlearis, 347. Cane sugar, 7. Canine teeth, 242. Canthus, of eye, 350. Capillaries, 146, 160. structure of, 157. Capillary circulation, 191. Capsule of Tenon, 122. Carbohydrates, 7, 8. absorption of, 270. Carbon dioxide, 10. Cardiac cycle, 154. Cardiac nerve, accelerator, 312. inhibitory, 312. Carotid arteries, common, 166. external, 166, 167. internal, 166, 167. Carotid glands, 216, 218. Carpus, bones of, 69, 70. Cartilage, 39. articular, 40. costal, 40. cricoid, 220. elastic fibro-, 40. hyaline, 40. skeletal, 40. summary of, 46. true, 40. varieties of, 40. white fibro-, 40. yellow fibro-, 40. Carunculae myrtiformes, 377. Casein, 9. Casts, in urine, 285. Cataract, 360. Cauda equina, 313. Cavities, of body, 19, 20, 22. abdominal, 19. Puccal, 20. cranial, 19. dorsal, 19. nasal, 20. pelvic, 20. thoracic, 19. ventral, 19. Cavities of body, contents of, 19, 20, 22. Cavity, glenoid, of scapula, 68. Cell, 14, 23. bipolar, 303. mastoid, 54. meanings of term, 54. Cell - continued. multipolar, 303. nerve, 303. summary of, 31. prickle, 28. unipolar, 303. Cell-division, 24. Centre, for hearing, 325. for memory, 325. for respiration, 228. for speech, 325. for vision, 325. Central canal of cerebro-spinal system, 324. Central lobe of cerebrum, 323. Centres in medulla, 319. Centrifugal fibres, 308. Centripetal fibres, 308. Cerebellum, 320, 333, 334. functions of, 321. peduncles of, 321. Cerebro-spinal axis, cavities of, 335. Cerebro-spinal system, 312, 334. Cerebrum, 321, 334. convolutions of, 323. cortex of, 333. fissures of, 322, 323. lobes of, 323. surface of, 323. Chemical affinity, definition of, 3. Chest, muscles of, 97, 99. Chordae tendine®, 152. Choroid, 354, 365. Chyle, 200. Chyme, 265, 266. Ciliary processes, 354, 365. Ciliated epithelium, 30. Circle of Willis, 167. Circumduction, 84. Circulation, of blood, 186, 197. abnormal variations in, 192. arterial, features of, 188. summary of, 183. change in inflammation, 192. connection of, with respiration, 232, 235. diagram of, 187. capillary, variations in, 191. factors governing, 188, 197. foetal, 193, 198. portal, 183, 185. pulmonary, 187, 197. summary of, 197. systemic, 187, 197. time of, 187. venous, 184, 190. Circumvallate papillae, 339. Clavicle, 67. Climacteric, 379. Clitoris, 377. Coagulation of blood, 141, 145. conditions, affecting, 142. hastening, 142. INDEX 427 Coagulation of blood - continued. conditions, hindering, 142. value of, 142. Coccygeal gland, 216, 218. Coccyx, 65. Cochlea, 346. Coeliac, artery, 169. axis, 169. Collar bone, 67. Colon, 250. ascending, 250. descending, 250. transverse, 250. • Colostrum corpuscles, 378. Columnae carneae, 152. Columnar epithelium, 29. Complementary air, 229. Compounds, chemical, 2, 5. definition of, 2. Conduction, nerve, 317. Condylarthrosis, 83. Condyles, of bone, 50. of femur, 72. Conjunctiva, 354. Connective tissues, 33. adenoid, 38. adipose, 37. areolar, 34. bone, 41. cartilage, 39. elastic, 36. fibrous, 35. lymphoid, 38. reticular, 38. retiform, 38. summary of, 45. varieties of, 34. Contractility, 86. Contraction, muscular, 112. Coordination, 318. Cord, umbilical, 194. Corium, 291. Cornea, 353, 365. white spots on, 360. Coronary veins, 177. Corpuscles, blood, 135, 144. development of, 196. Malpighian, of kidney, 277. number of, 135. of Golgi, 307. of Krause, 307. of Meissner, 307. of Pacini, 307. plates, 139, 144. red, 135, 144. diapedesis of, in inflammation, 193. renal, 277. tactile, 291, 300, 306, 337. white, 137, 144. migration of, in inflammation, 192. Corpus callosum, 321. Corpus luteum, 381. Corti, organ of, 347. Costal cartilage, 40. Coughing, 234. Cranial cavity, 19. nerves, 326, 335. Cranium, 51. bones of, 52. side view of, 15. Crest, of bone, 50. of ilium, 72. Cretinism, 214. Cricoid cartilage, 220. Crura cerebri, 322. Crying, 234. Crystalline lens, 359, 366. function of, 359. Cutaneous membrane, 126. Cutis vera, 291, 300. Cystic duct, 258. Cytoplasm, 23. Decidua menstrualis, 380. Defecation, 269. Deglutition, 264. Deltoid, 105. Dendrites, 303. Dermatology, definition of, 18. Dextrose, 7. Diapedesis, 137, 193. Diaphragm, 20, 100. Diarthroses, 82. Diastole, 153. Diffusion, 200. Digestion, 262, 269 (note), accessory organs of, 251, 259. in mouth, 263. in stomach, 265. intestinal, 266. summary of, 272. Digestive apparatus, 236, 259. juices, 272. Digits, of foot, 77. of hand, 70. Diploe, 49. Discus proligerus, 369. Dislocation, 84. Distal, 162. Dorsal, artery of foot, 176. cavity, 19. Douglas, pouch of, 375. Duct, bile, 257, 261. common bile, 258. cystic, 258. hepatic, 258. nasal, 351. thoracic, 203, 217. Ductless glands, 128, 211, 218. Ductus arteriosus, 193. communis choledochus, 258. venosus, 193, 195. Duodenal glands, 249. Duodenum, 247. 428 INDEX Dura mater, 318. Dyspnoea, 232. Ear, bones of, 78. external, 344, 363. internal, 346, 363. middle, 345, 363. Ectoderm, 27, 370. Ectopic gestation, 371. Efferent neurones, 308. Effusion, 207. Elastic tissue, 36. Elbow bone, 69. Elements, chemical, definition of, 1, 5. in human body, 5, 6. Elimination, 274, 286, 289. of waste products, 275, 286. Embryo, 26. Enarthrosis, 83. Endocardium, 150. Endolymph, 347. Endosteum, 42. Endothelium, 29, 120. Energy, definition of, 1. in the body, 14. measurement of, 14. Ensiform process, 65. Entoderm, 27, 370. Enzymes, 262, 272. Epidermis, 27, 289, 300. Epigastric region of abdomen, 238. Epiglottis, 220. Epimysium, 89. Epistropheus, 64. Epithelial tissue, 27, and see Epithe- lium. Epithelium, 27. ciliated, 30. columnar, 29. functions of, 27. glandular, 30. location of, 32. pavement, 29. scaly, 29. simple, 29. simple scaly, 29. stratified, 27. summary of, 32. transitional, 28. varieties of, 27. Equilibrium, sense of, 349, 364. Ether, definition of, 1. Ethmoid bone, 55. Eustachian tubes, 345. Excretion, 131. Exophthalmic goitre, 214. Expiration, 227. Extension, 84. Extensor muscles, of forearm, 106. of leg, 111. External oblique muscle of abdomen, 102. Extractives of plasma, 140. Extremities, 21. Exudation fluid, 193. Eye, accessory organs of, 350. muscles of, 91 and 352. nerves of, 328, 352. photographic function of, 357, 366. Eyeball, 352, 365. dimensions, 353. muscles of, 91 and 352. refracting media, 353, 358. tunics, 353, 365, 366. Eyebrows, 350, 364. Eyelashes, 350. Eyelids, 350, 364. Face, 51. bones of, 57. muscles of, 91. side view of, 15. Facial, artery, 162. nerve, 328. Fallopian tubes, 370, 382. Fascia?, 36, 111, 127. deep, 127. lumbar, 127. summary of, 132. superficial, 127. Fats, 8. action of pancreatic juice upon, 267. Fauces, 240. pillars of, 240. Feces, 269. Female generative organs, 367, 382. functional activity, 378, 384. Femoral, artery, 174. muscles, anterior, 108. internal, 111. posterior, 108. vein, 180. Femur, 72. Fenestra, ovalis, 345. rotunda, 345. Fever, 299, 301. Fibrinogen, 140. Fibro-cartilage, elastic, 40. white, 40. yellow, 40. Fibrous tissue, 35. Fibula, 74. Filiform papillre, 340. , Fimbriae of Fallopian tube, 371. Fistula;, recto-vaginal, 376. vesico-vaginal, 376. Flexion, 84. Flexor muscles, of forearm, 106. of leg, 111. Foetal circulation, 193, 198. Fontanelles of skull, 56. Food, action of bile upon, 268. of gastric juice upon, 265. of pancreatic juice upon, 267. of saliva upon, 263. Fats, 8. INDEX 429 Food- continued. changes undergone by, in large in- testine, 269. in mouth, 263. in stomach, 265. in small intestine, 266. uses of, 273. Food principles, 6. Food-stuffs, 272. final destination of, 271. Foot, bones of, 71, 75. digits of, 77. dorsum of, arteries of, 175. instep of, 76. phalanges of, 77. sole of, 76. Foramen magnum, 52. of bone, 50. of Munroe, 324. ovale, 150, 193. Forearm, muscles of, 106. Fossa, glenoid, 55. lacrimal, 54. of bone, 50. Fovea centralis, 357. Fracture, green-stick, 41. Frontal, bone, 53. lobe of cerebrum, 323. sinuses, 54. Fungiform papill®, 339. Gall-bladder, 258, 261. Ganglia, 310. on spinal nerves, 316. spinal, 333. sympathetic, 333. Gases in blood, 141. Gastric, artery, 169. juice, 133, 265, 273. action of, upon food, 265. Gastrocnemius, 111. Generative organs, female, 367, 382. functional activity, 378, 384. Genesiology, definition of, 18. Genioglossus, 94. Germinative layer of skin, 290. Gigantism, 215. Ginglymus, 82. Gladiolus, 65. Glands, 128, 132. Brunner's, 249. coccygeal, 216, 218. compound, 128. ductless, 128, 211, 218. duodenal, 249. intestinal, 249. lacrimal, 351. mammary, 377. Meibomian, 351. of Bartholin, 377. of stomach, 246. of vulva, 377. parotid, 240. Glands - continued. salivary, 240. sebaceous, 293, 300. secreting, 128. simple, 128. sublingual, 240. submaxillary, 240. sweat, 294, 301. tarsal, 351. urethral, 377. vulvo-vaginal, 377. Glandular epithelium, 30. Glenoid cavity, 68. Glenoid fossa, 55. Glisson's capsule, 258. Glomerulus, 279, 283. Glossopharyngeal nerve, 328. Glottis, 221. Glucose, 7, 8. Gluteus, maximus, 107. medius, 107. minimus, 107. Glutin, 9. Glycogen, 7. Glycogenic function of liver, 255. Glycosuria, 285. Goitre, 214. exophthalmic, 214. Golgi, corpuscles of, 307. Grape sugar, 7. Graves's disease, 214. Green-stick fracture, 41. Gristle, 39, and see Cartilage. Gullet, 244, 259. H®moglobin, 136, 137. reduced, 137. Hairs, 292, 300. Hamstring muscles, 108. Hand, body of, 70. bones of, 70, 71. Haversian, system, 44. canal, 44. Head, 51. muscles of, 91, 92. Hearing, 344. centre for, 325. summary of, 363. Heart, 146, 147. auricle, 150, 159. -beat, 153. cause of, 155. character of, 155, 188. regulation of, 155, 158. cavities of, 150, 159. chord® tendine®, 152. column® carne®, 152. murmurs, 155. papillary muscles, 152. sounds of, 155, 159. summary, 159. valves of, 151, 188. bicuspid, 152. 430 INDEX Heart - continued. valves of, semilunar, 153. tricuspid, 151. ventricle, 150, 159. Heat, bodily, 14, 296, 301. measurement of, 14. Heel bone, 74. Hemophilia, 142, 145. Hemorrhoidal artery, superior, 170. Hepatic, artery, 169, 258, 261. cells, 256. duct, 258. flexure, 250. vein, 257. Hiccough, 233. Hip, bones of, 71. Hippuric acid, 285. Housemaid's knee, 123. Humerus, 68. Hyaline cartilage, 40. Hyaloid membrane, 358. Hydrochloric acid in gastric juice, 265. Hymen, 377. imperforate, 377. Hyoid bone, 60. Hypermetropic eye, 359. Hyperpnoea, 232. Hypochondriac regions of abdomen, 283. Hypogastric, artery, 173. region of abdomen, 238. Hypoglossal nerve, 328. Hypophysis, 215, 218. Ileo-csecal valve, 250. Ileum, 247. Iliac, arteries, 173, 174. regions of abdomen, 238. veins, 180, 181. Ilium, 72. Incisor teeth, 242. Incus, 345, 346. Inferior, maxillary nerve, 328. turbinated bones, 58. Inflammation, circulatory changes in, 192, 198. Infundibulum, of Fallopian tubes, 371. of lungs, 226. Inguinal regions of abdomen, 238. Innominate, artery, 166. vein, 177, 179. Inorganic substances, definition of, 12. Inosculation of arteries, 162. Insalivation, 263. Inspiration, 227. Intercostal, arteries, 169. muscles, 98, 99, 100. Interlabial or vulvar cleft, 376. Interlobular veins, 256. Internal oblique muscle of abdomen, 103 Intervertebral disks, 62. Intestinal, glands, 249. ' juice, 268, 273. Intestine, large, 250, and see Large intes- tine. small, 247, and see Small intestine. thin, 247, and see Small intestine. thick, 250, and see Large intestine. Intralobular veins, 256. Involution of uterus, 373. Iris, 355, 365. Irritability, 86. Ischium, 72. Island of Reil, 323. Jejunum, 247. Joints, 79. ball-and-socket, 83. classification, 79. condyloid, 83. freely movable, 82. gliding, 82. hinge, 82. immovable, 79. movements of, 84. pivot, 83. reciprocal reception, 83. saddle, 83. slightly movable, 81. summary of, 84. sutures, 80. Judgments, 337. Jugular veins, 177. Katabolic, 275. Katabolism, 25. Kidneys, 276, 286. blood supply of, 278, 287. capsule, 276, 277. glomerulus, 279. matters eliminated by, 275, 286. papillre, 277. pelvis, 277. pyramids, 278. structure, 277. supports, 276. Knee-cap, 73. Knee, housemaid's, 123. Krause, corpuscles of, 307. Labia, majora, 376. minora, 376. Labyrinth, 346. bony, 346. membranous, 346. Lacrimal, apparatus, 351, 364. bones, 57. fossa?, 54. gland, 351. sac, 351. Lactation, 378. Lacteals, 202, 216. Lactose, 7. Laked blood, 137. Lamellae of bone, 42. Langerhans, islands of, 253. INDEX 431 Large intestine, 250, 260. changes undergone by food in, 269. coats of, 251. Larynx, 220, 221, 234. Latissimus dorsi, 97. Laughing, 234. Lecithin, 8. Leg, bones of, 71, 73. extensor muscles of, 111. flexor muscles of, 111. Legumin, 9. Levatores costarum, 100. Levator palpebrce superioris, 93. Lieberkuhn, crypts or follicles of, 249. Ligamenta flava, 62. Ligaments, 36. annular, 128. of uterus, 374. Ligamentum nuchae, 97. Light, 357. rays of, in hypermetropic eye, 359. in myopic eye, 359. in normal eye, 359. Limbs, 21. Linea alba, 103. Liver, 253, 261. fissures, 254. functions of, 255. ligaments, 254. lobes, 254. lymphatics, 258. minute anatomy, 256. nerves, 258. vessels, 255. Living matter, characteristics of, 13. Lower extremities, bones of, 70. muscles of, 107. Lower jawbone, 60. Lumbar, arteries, 173. fascia, 127. regions of abdomen, 238. Lungs, 224, 234. anatomy of, 226, 235. blood-vessels of, 226, 235. capacity of, 228, 235. lobule of, 225. matters eliminated by, 275, 286. Lymph, 199, 216. flow of, 203. function, 200, 216. movements of, 205, 217. sources of, 199. Lymph nodes, 208, 217. of lower limb, 205. of neck and upper thorax, 209. of upper limb, 204. purpose of, 209. Lymph nodules, aggregated, of Pever, 210. solitary, 210. special, 217. Lymph spaces, 201. Lymphatic duct, right, 203, 205, 217. part drained by, 206. Lymphatic, system, summary, 216. vessels, 201, and see Lymphatics. Lymphatics, 201, 202, 216. of lower limb, 205. of upper limb, 204. structure of, 202. Lymphoid tissue, 38. Macula lutea, 357, 366. Malar bone, 57. Malleolus, external, 74. inner, 73. lateral, 74. medial, 73. Malleus, 345, 346. Malpighian corpuscles, of kidney, 277. of spleen, 212. Malpighian layer of skin, 290. Maltose, 7. Malt sugar, 7. Mammary glands, 377. Mandible, 60. Manubrium, 65. Maple sugar, 7. Margarin, 8. Marrow of bone, 42. Mastication, 263. muscles of, 93. Mastoid, cells, 54, 346. process, 54. Matter, composition of, 1. constitution of, 2. definition of, 1. living, characteristics of, 13. structure of, 2. Maxilla, 59. Measurements, tables of, 26. Meatus of bone, 50. Mediastinal arteries, 169. Medulla oblongata, 319, 333, 334. centres in, 319. functions of, 319. Medullary canal of bone, 42. Medullary sheath, 305. Medullated nerve-fibres, 304. Meibomian glands, 351. Meissner, corpuscles of, 307. Membrana, tympani, 345, 346. granulosa (of ovary), 368. Membrane, or membranes, 36, 120, 131. cutaneous, 126. mucous, 30, 123, and see Mucous mem- brane. pituitary, 343. Schneiderian, 343. serous, 120, and see Serous membranes. special, 120. synovial, 122, and see Synovial mem- branes. Memory, centre for, 325. 432 INDEX Meninges of brain, 318. Menopause, 379. Menstrual discharge, character of, 380. Menstruation, 379, 384. and ovulation, 378, 381. duration of, 380. frequency of, 379. nature of, 380. Mesenteric artery, inferior, 170. superior, 170. Mesentery, 122, 248. Meso-colon, 122. Mesoderm, 27, 370. Metabolism, 14, 24, 25, 274, 285. Metacarpus, bones of, 70. Metastasis, 210. Metatarsus, 76. Metric system, 385. Micturition, 284. Milk, 133, 378, 384. Milk sugar, 7. Mineral salts in body, 6. Mixtures, mechanical, 2. Molar teeth, 243. Molecule, definition of, 2. Mons Veneris, 376. Motor, areas of brain, 325. fibres, 308, 316. plates, 306. Mouth, 239, 259, and see Buccal cavity changes undergone by food in, 263. digestion in, 263. muscles about, 94. Mucous membranes, 30, 123, 132. gastro-pulmonary, 124. genito-urinary, 124. modifications of, 216. structure of, 125. Mucus, 133. Muscle, or muscles, 86, 89. adductors of thigh, 111. anterior femoral, 108. attachment of, to skeleton, 89. biceps, of arm, 105. of leg, 108. buccinator, 93. classification of, 86. contraction of, 86, 88. contractor of pupil, 355. deltoid, 105. diaphragm, 100. dilator of pupil, 355. epicranial, 91. extensors of forearm, 106. external oblique, of abdomen, 102. flexors of forearm, 106. forms of, 90. gastrocnemius, 111. genioglossus, 94. gluteus, maximus, 107. medius, 107. minimus, 107. groups of, 91. Muscle, or muscles - continued. hamstring, 108. inferior oblique, of eyeball, 92. insertion of, 89. intercostals, 98, 99, 100. internal femoral, 111. oblique, of abdomen, 103. involuntary, 87, 88. latissimus dorsi, 97. levator palpebrae superioris, 93, 350. levatores costarum, 100. non-striated, 87, 88. number of, 91. occipito-frontalis, 91. of abdomen, 102. action of, 104. of back, 96, 98. of chest, 97, 99. of eyeball, 91, 352. of face, 91. of forearm, 106. of head, 91, 92. of heart, 87. of lower extremity, 107. of mastication, 93. of mouth, 94. of neck, 91, 92, 96. of orbit, 93. of shoulder, 99. of thorax, 98. of tongue, 94, 95. of trunk, 96. of upper extremity, 104. orbicularis oris, 93. orbicularis palpebrarum, 350. origin of, 89. pectoral, 97. pectoralis major, 97. minor, 97. peroneal, 111. plain, 87. platysma, 96. posterior femoral, 108. pronators of forearm, 106. properties of, 86. psoas magnus, 107. pterygoids, 95. quadriceps extensor, 109. recti, of eyeball, 91. rectus, abdominis, 103. femoris, 109. relation of, to nerves, 111 sartorius, 110. semimembranosus, 108. semitendinosus, 108. skeletal, 87. soleus, 111. sterno-cleido-mastoid, 96. striated, 87. striped, 87. styloglossus, 96. summary, 112. superior oblique, of eyeball, 92. INDEX 433 Muscle, or muscles - continued. supinators of forearm, 106. tables of, 113-119. temporal, 94. tibialis, anterior, 111. posterior, 111. transversalis, 103. trapezius, 97. triceps, 105. vastus, externus, 109. intermedius, 109. internus, 109. visceral, 87. voluntary, 87. Muscular, contraction, 112. sense, 338. tissue, 86, and see Muscle. Muscularis mucosae, 125. Myelin sheath, 305. Myocardium, 147. Myology, definition of, 18. Myopic eye, 359. Myosin, 9. Myxoedema, 214. Nails, 292, 300. Nasal, bones, 57. cavity, 20. duct, 351. fossae, 342. Neck, muscles of, 91, 92, 96. Nerve, or nerves, 333. abducens, 328. auditory, 328. -cell, 303. cranial, 326, 335. degeneration of, 317. -endings, 305, 333. facial, 328. -fibre, 304, 333. medullated, 304. non-medullated, 305. ganglia, 334. glossopharyngeal, 328. hypoglossal, 328. impulse, 334. direction of, 307. nature of, 307. speed of, 309. inferior maxillary, 328. oculomotor, 327. of eye, 328, 352. of nose, 328. of special sense, 337. of tongue, 328. olfactory, 327, 343. ophthalmic, 327. optic, 327. pathetic, 327. pneumogastric, 328. processes, 303. regeneration of, 317. relation of muscles to, 111. Nerve, or nerves - continued. spinal, 315. spinal accessory, 328. stimulation, artificial, 307. physiological, 307. superior maxillary, 327. trifacial, 327. trochlear, 327. trunks, 334. formation of, 309. vaso-constrictor, 188. vaso-dilator, 188. Nervous system, 302, 333. Neuraxon, 303, 304. Neurology, definition of, 18. Neurilemma, 305. Neurones, 302, 333. afferent, 308. efferent, 308. Non-medullated nerve-fibre, 305. Nose, 342, 362. external, 342. nerves of, 328. Nostrils, 342. Nucleus of cell, 23. Oblique muscles of eyeball, 92. Occipital, bone, 52. lobe of cerebrum, 323. Occipito-frontalis, 91. Oculomotor nerve, 327. Odontoid process, 64. Odours, 341. (Edema, 207, 217. CEsophageal arteries, 169. (Esophagus, 244, 259. Olecranon process, 69. Olein, 8. Olfactory, bulb, 343. nerve, 327, 343. Omentum, 38, 122. Opsonins, 139, 144. Ophthalmic nerve, 327. Optic, commissure 327. nerve, 327. Orbicularis oris, 93. Orbit, 352. Orbital muscles, 93. Organ, definition of, 25. of Corti, 347. Organic substances, definition of, 12. Os coxae, 71. Osmosis, 200. Osseous tissue, 41, and see Bone. Osteology, definition of, 18. Otoliths, 349. Ovarian, arteries, 172. mound, 369. Ovaries, 367. Oviducts, 370. Ovulation, 378, 380, 384. and menstruation, 378, 381. 434 INDEX Ovum, 26, 369, 382. fecundated, development of, 369. Oxidation, 4, 24, 232. Oxide, basic, definition of, 12. Oxyli£emoglobin, 137, 231. Pacini, corpuscles of, 307. Pain, 336. Palate, 239. Palate bones, 58. Palatine arches, 240. Palmar arch, deep, 169. superficial, 169. Palmitin, 8. Pancreas, 251, 261. structure, 252. Pancreatic juice, 133, 266, 273. action of, upon food, 267. Papillre, of skin, 291, 300. of tongue, 339. on mucous membrane, 126. Papillary muscles, 152. Paraglobulin, 140. Parathyroids, 214, 218. Parietal, bones, 53. lobe of cerebrum, 323. Parotid glands, 240. Patella, 73. Pathetic nerve, 327. Pavement epithelium, 29. Pectoralis, major, 97. minor, 97. Pectoral muscles, 97. Pelvic cavity, 20. Pelvis, false, 77. female, 76, 77. inlet, 77. male, 76, 77. outlet, 77. strait, 77. true, 77. Peptones, 9. Pepsin, 265. Perceptions, 337. Pericardial arteries, 169. Pericardium, 121, 148. Perichondrium, 41. Perilymph, 122, 346. Perineum, 377. Periosteum, 44. function of, in growth of bone, 44. Peristalsis, 251. Peritoneum, 122. Peroneal, artery, 175. muscles, 111. Perspiration, 295, 301. insensible, 295. quantity, 295, 301. sensible, 295. uses, 301. Peyer's gland, or lymph nodule, or patches, 210, 249. Phagocytosis, 139. Phalanges, of foot, 77. of hand, 70. Pharynx, 243, 259. Photographic function of eye, 357, 366. Phrenic arteries, 173. Physiology, definition of, 15. Pia mater, 318. Pinna, 344. Pituitary, body, 215, 218. membrane, 343. Placenta, 194. functions of, 195. Plantar, arch, 1'76. arteries, 175. Plasma, 135, 140, 145. Platysma, 96. Pleura, 121, 224, 235. Plexus, arterial, 162. Pneumogastric nerve, 328. Pons Varolii, 321, 333, 334. functions of, 321. Popliteal artery, 174. Portal, circulation, 183, 185. system, 181. vein, 183, 256, 261. Premolar teeth, 242. Pressure sensation, 338. Prickle cells, 28. Principles, food, 6. proximate, 6. Process, acromion, 68. ensiform, 65. mastoid, 54. odontoid, 64. olecranon, 69. xiphoid, 65. Pronator muscles of forearm, 106. Protecting sheaths, 36. Proteids, 8. absorption of, 270. action of gastric juice on, 265. of pancreatic juice on, 267. Protoplasm, characteristics of, 13. composition of, 13. Proximal, 162. Proximate principles, 6. Pseudo-vacuoles, 137. Psoas magnus, 107. Pterygoid muscles, 95. Ptyalin, 264. Puberty, 379. Pubes, 72. Pulmonary, artery, 164. , circulation, 187. veins, 177. Pulse, 189, 197. frequency, 189, 197. ratio of, to respiration, 190. variations in, 189, 197. Pupil, of eye, 355. contraction of, 355. dilatation, 355. Pubes, 72. INDEX 435 Pylorus, 244. Pyrexia, 299, 301. Quadriceps extensor muscle, 109. Rachitis, bones in, 41. Radial, artery, 169. veins, 178. Radius, 69. . Rales, 229. Ranvier, nodes of, 305. Reaction, chemical, 5. Receptaculum chyli, 205. Recti muscles of eyeball, 91. Recto-vaginal septum, 376. Rectum, 251. Rectus, abdominis, 103. femoris, 109. Reflex, act, 317, 328, 329. arc, inhibition of, 318, 329, 330. Remak, fibres of, 305. Renal, arteries, 171. corpuscles, 277, 286. Rennin, 265, 266. Reserve air, 229. Residual air, 228. Respiration, 101, 219, 227, 235. abdominal, 101. connection of, with circulation, 232, 235. costal, 101. diaphragmatic, 101. effect of first, 228. effects of, upon the air, 229, 235. effects of, upon the blood, 231, 235. frequency of, 227. rate of, 235. ratio of, to pulse, 190. Respiratory, apparatus, 219. centre, 228. movements, modified, 233. sounds, 229. Restiform bodies, 321. Reticular tissue, 38. Retiform tissue, 38. Retina, 356, 366. layers of, 366. Ribs, false, 66. floating, 66. true, 66. Rotation, 84. Round ligament of uterus, 374. Rugae, of stomach, 246. of vagina, 376. on mucous membrane, 126. Sacral artery, middle, 173. Sacrum, 65. Saliva, 133, 241, 263, 272. action of, upon food, 263. Salivary glands, 240, 259. abdominal, 252, 266. Salt, and see Sodium chloride. definition of, 12. mineral, in body, 6. of plasma, 140. Saphenous veins, external, 180. internal, ISO. long, 180. short, 180. Sarcolemma, 87. Sartorius, 110. Scala media, 347. Scaly epithelium, 29. Scapula, 68. Scarpa's triangle, 174. Schneiderian membrane, 343. Schwann, sheath of, 305. Sclera, 353, 365. Sebaceous glands, 293, 300. Sebum, 133, 293. Secreting glands, 128, 129. Secretions, 130, 133. external, 130. internal, 130. table of, 133. Secretory apparatus, 129. Semicircular canals, 346, 349. Semilunar valves, 153. Semimembranosus, 108. Semitendinosus, 108. Sensations, and perceptions, 337. classifications of, 336, 361. common, 336, 361. difference between common and spe- cial, 337. special, 336, 361. Sensation, organs necessary for, 336, 361. pressure, 338. Sense, muscular, 338. of equilibrium, 349. of hearing, 344. of sight, 350. of smell, 341. of taste, 339. of temperature, 338. of touch, 337. Sensory, apparatus, 336. area of brain, 325. fibres, 308, 316. Serous, sacs, 202, 217. membranes, 120, 131. classes of, 120. of cavities, 122. of cerebrospinal axis, 122. of vascular system, 122. proper, 121. secretion, 133. Serum, 142. albumin, 140. Sharpey, fibres of, 44. Shin-bone, 73. Shoulder, blade, 68. muscles of, 99. Sighing, 233. 436 INDEX Sight, 350, 357, 358, 364, 366. Sigmoid flexure, 251. Simple epithelium, 29. Sinews, 36. Sinuses, frontal, 54. of bone, 50. • venous, of skull, 178. Skeletal cartilage, 40. Skeleton, 47. attachment of muscles to, 89. divisions of, 51. Skin, 289, 300. appendages, 292, 300. functions, 289, 296, 301. layers, 289, 300. matters eliminated by, 275, 286. summary, 300. true, 291. Skull, 50, 51. as a whole, 56. diploe of, 49. foetal, diameters and landmarks of, 80, 81. venous circulation of, 177. Small Intestine, 247, 260. changes undergone by food in, 266. coat of, 248. digestion in, 266. divisions of, 247. glands of, 249. Smell, 341, 362. and taste, 341. necessary conditions for, 341. Sneezing, 234. Sobbing, 233. Sodium chloride in body, 6. Soleus, 111. Sounds, 348. Speaking, 234. Special sense, nerves of, 337. organs, 307. Speech, centre for, 325. Spermatic arteries, 172. Sphenoid bone, 55. Spinal-accessory nerve, 328. Spinal, canal, 19. cord, 313, 333, 334. central canal of, 315. functions of, 317. membranes of, 313. nerves emerging from, 316. sections of, 314, 315. ganglia, 333. nerves, 315. Spinous processes, 50. of ilium, 72. Spittle, 263. Splanchnology, definition of, 18. Spleen, 212, 218. Splenic, artery, 170. flexure, 250. Sprain, 84. Stability of substances, 4. Stapes, 345, 346. Starch, 7. action of saliva on, 264. of pancreatic juice on, 267. animal, 7. Stasis, 193. Steapsin, 267. Stearin, 8. Sterno-cleido-mastoid, 96. Sternum, 65. Stimuli, 86. Stomach, 244, 260. blood-vessels of, 246. changes undergone by food in, 265. coats of, 246. digestion in, 265. glands of, 246. nerves of, 246. Stratified epithelium, 27. Stratum, corneum, 290. granulosum, 290. lucidum, 290. Styloglossus, 96. Subclavian, arteries, 167. veins, 177, 178. Sublingual glands, 240. Sublobular veins, 256. Submaxillary glands, 240. Succus entericus, 133, 268. Sucrose, 7. Sugars, 7. Superior maxillary nerve, 327. Supinator muscles of forearm, 106. Supra-renal capsules, 215, 218. Surface parts, names of, 15, 16, 17, 18 Sutural bones, 57. Sutures, 79. coronal, 80. lambdoidal, 80. of skull, 80. sagittal, 80. Swallowing, 264. Sweat, 133, 295, and see Perspiration. Sweat-glands, 294, 301. Symbols, chemical, 5. Sympathetic, ganglia, 333. system, 310, 335. function of, 312, 335. Symphysis pubis, 72. Synarthroses, 79. Synchondrosis, 80. Syndesmology, definition of, 18. Synovial, membranes, 122. articular, 123. bursal, 123. summary of, 132. vaginal, 123. Syntonin, 9. System, definition of, 26. Systole, 153. Tactile, corpuscles, 291, 300, 306, 337. menisci, 307. INDEX 437 Tarsal glands, 351. Tarsus, bones of, 74. of eye, 350. Taste, 339, 361. and smell, 341. necessary conditions, 339. organ of, 339. sense of, 339. Taste buds, 341. Tears, 133, 351, 365. Teeth, 241, 242. deciduous, 241. permanent, 241. Temperature, abnormal, 301. sense of, 338. • subnormal, 299, 301. Temporal bones, 54. mastoid portion of, 54. petrous portion of, 54. squamous portion of, 54. Temporal muscle, 94. Temporo-sphenoidal lobe of cerebrum, 323. Tendo A chillis, 111. Tendons, 36, 89. Tenon, capsule of, 352. Tension, arterial, 190, 191. Thigh, adductor muscles of, 111. bones of, 71, 72. Thoracic, aspiration, 207. cavity, 19. duct, 203, 217. part drained by, 206. Thorax, 64, 65. bones of, 65. muscles of, 98. Thymus, 215, 218. Thyroid, 213, 218. cartilage, 220. foramen, 72. Tibia, 73. Tibial, arteries, 174, 176. veins, 180. Tibialis, anterior, 111. posterior, 111. Tidal air, 228. Tissue, or tissues, 25. adenoid, 38. adipose, 37. areolar, 34. classification of, 26. connective, 33, and see Connective tissues. definition of, 25. elastic, 36. epithelial, 27, and see Epithelial tissue. fibrous, 35. liquid, 26. lymphoid, 38. muscular, 86, and see Muscle. origin of, 26. osseous, 41, and see Bone. Tissue, or tissues - continued. reticular, 38. retiform, 38. Tone of arteries, 188, 191. Tongue, 241, 339, 362. muscles of, 94, 95. nerves of, 328. sensations in, 341. Tonsils, 211, 240. Touch, 337, 3G1. acuteness of, 338. varieties of, 338. Trachea, 223, 234. Transference of nerve impulses, 318 Transitional epithelium, 28. Transudation, 199. Transversalis, 103. Trapezius, 97. Triceps, 105. Tricuspid valve, 151. Trifacial nerve, 327. Trochanters of femur, 72. Trochlear nerve, 327. Trochoides, 83. Trunk, bones of, 61. muscles of, 96. Trypsin, 267. Tubercle of bone, 50. Tunics of eye, 353, 365, 366. Tympanum, 345. ossicles of, 345, 346. Ulna, 69. Ulnar, artery, 169. veins, 178. Umbilical region of abdomen, 238. Upper extremities, bones of, 66. muscles of, 104. Upper jaw-bones, 59. Urea, 285. Uremia, 285. Ureters, 279, 287. Urethra, 281, 288. Urethral glands, 377. Uric acid, 285. Urinary system, 276, 286. Urine, 133, 282, 288. abnormal constituents, 285, 288. amount, 283. composition, 285, 288. excretion, 284, 288. secretion, 283, 288. Uriniferous tubules, 277. Uterine, artery, 162. tubes, 370, 382. Uterus, 371, 382. atrophy of, 373. blood supply, 373. cervix, 372. coats of, 373. during pregnancy, 373. fundus, 372. hypertrophy of, 373. 438 INDEX Uterus - continued. involution of, 373. ligaments, 374, 383. malpositions of, 374. os, 373. Uvula, 239. Vagina, 375, 383. Valve, or valves, ileo-caecal, 250 of heart, 151, 188. of veins, 158. Valvulae conniventes, 126, 248. Vasa vasorum, 157, 160. Vascular system, 134, 146, 161, 186. 199. Vaso-constrictor nerves, 312. Vaso-dilator nerves, 312. Vasomotor nerves, 157, 160, 312. Vastus externus, 109. intermedius, 109. internus, 109. Vein, or veins, 146, 160, 176. axillary, 178. azygos, 183. brachial, 178. brachiocephalic, 177, 179. cava, ascending, 177, 182. descending, 177, 180. inferior, 177, 189. superior, 177, 180. coronary, 177. deep, 177. femoral, 180. hepatic, 257. iliac, common, 181. external, 180. internal, 181. innominate, 177, 179. interlobular, 256. intralobular, 256. jugular, external, 177. internal, 177. portal, 183, 256. portal system, 181, 183. pulmonary, 177. radial, 178. saphenous, external, 180. internal, 180. long, 180. short, 180. severed, flow of blood from, 190. structure of, 157. subclavian, 177, 178. subcutaneous, 177. sublobular, 256. systemic, 177. tibial, anterior, 180. posterior, 180. ulnar, 178. valves of, 158. Vena cava, ascending, 177, 182. inferior, 177, 182. superior, 177, 180. descending, 177, 180. Venae comites, 177. Venous circulation, 176, 190. of skull, 177. Ventilation, 230. Ventral cavity, 19. Ventricles, of brain, 324. of heart, 150. Vermiform appendix, 250. Vernix caseosa, 294. Vertebrae, 63. false, 62. number of, 62. regions of, 62. true, 62. Vertebral column, as whole, 61. bones of, 62. curvatures of, 62. Vesicular follicles of ovary, 368. Vestibule, 346, 349. Vibrations, sound, 348. Villi, 126, 249. Viscera, definition of, 18. Vision, 360, and see Light. centre for, 325. Visual apparatus, 350. Vital capacity, 229. Vitellin, 9. Vitelline membrane, 369. Vitreous humour, 358, 366. Vocal, cords, 221. folds, 221. Voice, 222. Vomer, 57. Vulva, 376. glands of, 377. Vulval cleft, 376. Vulvo-vaginal glands, 377. Waste products, 275, 286. elimination of, 275, 286. Water, 11. in body, 6. Wharton's jelly, 194. Windpipe, 223. Wisdom teeth, 243. Wormian bones, 57. Wrist, bones of, 69, 70. Xiphoid process, 65. Yawning, 233. Yellow spot. 357. Zona pellucida, 369. Zone, peripheral, 192. By ISABEL McISAAC Primary Nursing Technique Cloth, i2mo, $1.25 net This is a thoroughly honest book for nurses starting on their course of study. It is written with the one object in view of inculcating in the minds of its readers the fact that an accurate knowledge of the human body is the first essential to successful nursing. The author also urges thoroughness and patience as the sine qua non of the nurse. The diction of the book is admirably clear. Hygiene for Nurses Cloth, i2mo, $1.25 net "The pages of this book are full of just the information that every woman in charge of souls and bodies needs. The chapters on food, ventilation, sewage, causes and dis- semination of disease, household, personal, and school hy- giene, the hygiene of occupation, disinfection, etc., are all of the most vital general interest and should be taken to heart by every one. The task is made easy by the excel- lent printing of the little book, . . . which will be found an excellent book of reference." - Philadelphia Public Ledger. The Elements of Hygiene for Schools Cloth, 12mo, $ .60 net The author's chief aim in this book has been to present the principles of hygiene intelligently and impressively, for the sake of helping the large number of school children who, after leaving school, probably will have no further oppor- tunities to study those principles. She has undertaken to show these young people how they may have vigor of mind and body through the observance of a few simple rules in respect to food, water, air, drainage, clothing, occupation, and exercise. PUBLISHED BY THE MACMILLAN COMPANY 64-66 Fifth Avenue, New York By CLARA BARRUS Nursing the Insane Clot]), 8vo, $2.00 net "This book ... is the outgrowth of fifteen years' experi- ence as physician in the hospital for the insane at Mid- dletown, New York, and without question it is the most valuable work on the subject yet published. . . . The training of nurses for the special care of the insane must cover a much wider field than that of the ordinary trained nurse. . . . Miss Barrus approaches the subject in entirely the right spirit. She recognizes that while the nurse for the insane has much to do as regards physical treatment, and scientific knowledge will be valuable to her, the prime requisite is common sense. Every nurse in a hospital for the insane should have this book and use it, for its chap- ters deal with almost every problem which can arise in an institution of this character."- The Boston Transcript. " Literature on the science of nursing has received a valu- able addition in the recent contribution of Dr. Barrus. It is an illuminative, sensible, straightforward series of talks On the various features of the nurse's work in caring for the insane. Although evidently intended for professionals, it is likewise of great interest to the lay reader and will abundantly reward him for the reading." - The Chicago R ecord-Herald. "There are here directions not only for the medical and clinical care of the insane, for their occupation and amuse- ments, with directions as to how they may be moved, and even the details of the nurse's duties when death intervenes in a case, but above all there are some very interesting chapters on psychology, so that the nurse may appreciate patients' states of mind and sympathize with their peculi- arities." - The Independent. PUBLISHED BY THE MACMILLAN COMPANY 64-66 Fifth Avenue, New York