\ - BRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEOICINII ABVlBII IVNOIIVN 3NOI03W JO AiVDIl IVNOIIVN 3NI3I03W JO AlVaail IVNOIIVN , nV '* for-- BRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINEI i Aavaan ivnouvn jnidiqjw jo Aavaan ivnouvn inidioiw jo Aavaan ivnoiivni \ j£\/ 1 BRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINEI *! fcilg lam jo Aavaan ivnouvn indiqiw jo Aavaan ivnouvn inuioiw jo Aavaan ivnc ,03w jo Aavaan ivnouvn 3N.d.o3w jo a.v.an ivnouvn inid. / 1 \943 Entered, according to Act of Congress, in the year 1843, by William E. Horner, in the Clerk's Office in the District Court of the Eastern District of Pennsylvania. ./^U>^.^^* tJ)^. fin-tC<*+ TABLE OE CONTENTS, VOLUME II. BOOK IV. PART II.—Organs of Assimilation, - - f- Chap. I.—Prolegomena on Structure of Glands, II.—Abdomen, generally, III-—Of the Peritoneum and Serous Membranes, gene- rally, - Sect.—1.—Peritoneum, - - - , 2.—Omenta, ... 3.—Histology of Serous Membranes, Chap. IV.—Chylopoietic Viscera, - Sect. 1.—Stomach, - 2.—Intestinal Canal, 3.—Minute Anatomy of the Mucous Coat of the Alimentary Canal, - 4.—Histology of Mucous Membranes, Chap. V.—Assistant Chylopoietic Viscera^ Sect. 1.—Liver, .... 2.—Spleen, 3.—Pancreas, Of the Urinary Organs, - BOOK V. i BOOK VI. afS*» Organs of'Generation, t Chap. I.—Male Organs of Generation, - Sect. 1.—Penis, - 2.—Mucous Glands and Apparatus, 3.—Testicles, - 4.—Muscles and Fasciae of Perineum, Page 5 5 12 17 17 19 24 29 29 35 48 58 64 64 74 78 97 97 97 103 106 114 CONTENTS. Page Chap. II.—Female Organs of Generation, - - - 120 Sect. 1.—Vulva, - - - - - - 120 2.—Vagina, ----- 124 3.—Uterus, and its Appendages, - - - 126 Chap. III.—Breasts, - - - - - 136 BOOK VII. Organs op Respiration, - - - - - -141 Chap. I.—Larynx, - - - -. - 141 II.—Trachea, and Glands bordering upon it, - - 151 Sect. 1.—Trachea, and Bronchia, - - - 151 2.—Thyroid Gland, - - - - - 155 3.—Thymus Gland, - - - - 157 Chap. HI.—Lungs, - - - - - -159 BOOK VIII. Circulatory System, - - - - - 169 PART I.—Histology of Circulatory System, - - - 169 Chap. I.—General Considerations, - - -- -* 169 II.—Arteries, - - - - - - 183 III.—Veins, - - - - - 190 IV.—Blood, - - - - - - 193 Sect. 1.—Serum, - - - ~ - 198 2.—Fibrine, - - - - - - 200 3.—Red Globules, - - - - - 201 PART II.—Special Anatomy of Circulatory System, - - 207 Chap. I.—Heart, and Pericardium, ... 207 II.—Arteries, - - - - - - 219 Sect. 1.—Aorta and the Branches from its Curva- ture, 219 2.—Carotids and their Branches, - - . 222 ' 3.—Subclavian and Branches, - - - 231 4.—Branches of Descending Thoracic Aorta, - - 243 5.—Branches of Abdominal Aorta, -" .^- - 245 6.—Common Iliacs, - - f - . 252 7.—Internal Iliacs, - - - .' \ fc53 8.—External Iliacs, - 258 Chap. III.—Veins, - - - - . - 271 Sect. 1.—Veins of Head and Neck, - - - - 271 2.—Veins of Upper Extremities,. - - - 280 CONTENTS. Page Sect. 3.—Veins of Lower Extremities, - - -283 4.—Veins of Abdomen - 285 5.—Vena portarum, ----- 289 Chap. IV.—Peculiarities of the Circulatory System in the Foetus, ----- 292 Sect. 1.—Peculiarities of Foetus, &c, - - -292 2.—Peculiarities of Circulation of Foetus, &c, - 296 Chap. V.—Histology of Absorbent System, - - -301 VI.—Special Anatomy of Absorbent System, - 310 Sect. 1.—Absorbents of Head and Neck, - - -310 2.—Absorbents of Upper Extremities, - - 312 3.—Absorbents of Inferior Extremities, - - 314 4.—Deep Absorbents of Pelvis, - - - 316 5.—Absorbents of Organs of Digestion, - - 318 6.—Absorbents of Viscera of Thorax, - - 324 7.—Absorbents of Parietes of Trunk, - - 326 8.—Thoracic Ducts, - 329 BOOK IX. Of the Nervous System, - 333 PART I.—Histology of the Nervous System, - - 333 II.—Special Anatomy of the Central Poition of the Nervous System, ..... 347 Chap. I.—Medulla Spinalis, and its Membranes, - - 347 Sect. 1.—Membranes of Spinal Marrow, ' - - 347 2.—Medulla Spinalis, .... 350 3.—Blood Vessels of Medulla Spinalis, - - 357 Chap. II.—Encephalon, - 358 Sect. 1.—Membranes of Brain, ... 359 2.—Medulla Oblongata, - 369 3.—Protuberantia Annularis, - - - 372 4.—Cerebellum, - 373 5.—Cerebrum, - 376 6.—Nerves of Encephalon, - 392 7.—Arteries of Brain, - 401 PAl^T III.—Senses, - - - - - - 405 Chap. I.—Nose, - - - - 405 II.—Eye, - - - - - - 415 Sect. 1.—Auxiliary parts of Eye, - - - 415 2.—Eyeball, - - ■- - - 431 CONTENTS. Page Chap. III.—Ear, - - 451 Sect. 1.—External Ear, 452 2.—Tympanum, - 456 3.—Labyrinth, - 462 4.—Nerves, ... - 468 PART IV.—Special Anatomy of Nerves, 471 ■ Chap. I.—Nerves of Encephalon, - - 471 Sect. 1.—Nervus Olfactorius, 471 2.—-Nervus Opticus, - 471 3.—Nervus Motor Oculi, 472 4.—Nervus Trochlearis, - 472 5.—Nervus Motor Externus, 473 6.—Nervus Trigeminus, - 473 7.—Nervus Facialis, 483 8.—Nervus Hypoglossus, - 485 9.—Nervus Accessorius, 487 10.*—Nervus Glosso-Pharyngeus, - 488 11.—Nervus Pneumogastricus, - 489 Chap. II.—Sympathetic Nerve, - 494 III.—Nerves of Medulla Spinalis, 506 Sect. 1.—Upper Nine Spinal Nerves, - 506 3.—Thoracic Spinal Nerves, 517 3.—Abdominal Spinal Nerves, - 519 A TREATISE ON ANATOMY, BOOK IV. PART II. GLANDS-AND THE ORGANS OF ASSIMILATION, CHAPTER I. Prolegomena on the Structure of Glands. The intimate structure of glands was but imperfectly attended to previously to the celebrated Malpighi, who, in the year 1665, pre- sented to the world his work entitled Exercitationes de Structura Viscerum. Till his time the most minute inquiry had gone but little beyond the point of observation, that glands consisted, as an ultimate arrangement of their particles, in small granular bodies called Acini, from their being clustered like grapes or berries, growing very closely together around a common stem and its branches^ The simple idea, propounded by Malpighi, is, that each acinus being a gland of itself, consists of minute spheroidal sacs, which re- ceive the secretion from the blood vessels. Darwin at a much later period modified this idea by advancing that the change occurred in the spheroidal sacs themselves. The celebrated Ruysch having im- proved much the art of injection, was enabled to show in his pre- parations, that what Malpighi considered as sacs or follicles, were really formed of convoluted blood vessels. He hence adopted the opinion, false in itself, that the substance proper of glands, is Vol. II.—2 6 ORGANS OF DIGESTION. formed wholly of blood vessels, and that the minute branches of the latter terminate by direct inosculation with the ducts of the glands. As another step in this inquiry, Mascagni and Cruikshank showed that the secreting canals in the mammary glands com- mence in the form of cells—and Professor Weber has discovered the same feature to exist in the structure of the salivary glands of birds and mammalia, and of the pancreas of birds. The existing state of opinions on this interesting subject, is de- rived from J. Miiller, Professor of Anatomy, Berlin, who* has announced as the result of his inquiries on the structure of the se- creting canals in all kinds of secreting glands, that such canals are found every where to form an independent system of tubes. " That whether they be convoluted, as in the kidney and testis, or ramified in an arborescent form, as in the liver and salivary glands —whether they terminate by twig-like coeca, as in the liver—or in grape-like clusters of cells, as in the salivary glands, pancreas and mammary gland—their only connexion with the blood vessels in all cases, consists in the latter ramifying and forming a capilla- ry net-work on their walls and in their interstices: and that the finest secreting tubes, namely, those of the liver and kidneys, are always several times larger in diameter than the minute ramifica- tions of the arteries and the veins." This doctrine is, therefore, a modified resumption of the more ancient one of Malpighi, and claims merely for the entire surface of secreting tubes what Malpighi thought to belong exclusively to their incipient extremities. The leading argument in its favour being, that in every case there is a minute vascular net-work of capillaries discernible on the parietes of these canals, and whose capillaries are much smaller than the secreting tubes themselves.+ Glands of the most simple shape are mere recesses or pouches in the thickness of the membrane or surface to which they belong. (Folliculi.) In some instances they are very superficial and their bottom is reached through a wide orifice—in other instances their mouths are somewhat contracted like the neck of a bottle__in other cases they have a long and tortuous course (Tubuli) as the tubuli seminiferi of the testicle. In most of these modifications of a tubular arrangement, from the shortest to the most elongated * De Gland. Struct. Penit. Leips. 1830, and Physiol, p. 485. London, 1840. t See capillaries. GLANDS. 7 the walls of the tube are not absolutely uniform, but it will be found that there are either partial or cellular dilatations of it; or coecal-like appendages, in great numbers discharging into it, and placed in varied angular relations to the principal sinus or se- creting tube. The stem of a thickly clustering bunch of grapes, the berries being removed, will represent sufficiently well the mere mechanism of this arrangement. A form of secreting canal a little more complex is where a large sphenoidal dilated sinus exists with tubules radiating from it (Folliculi aggregati) in lines more or less regular, the sinus itself having a large patulous orifice connecting it with the surface upon which it discharges. One of the follicles of the tonsil glands may represent this arrangement. Also the glandulse linguales on the root of the tongue, which seem to be a mere extension of the lower end of the tonsil gland in the form of an expanded flank, and are not unfrequently, directly continuous with the tonsil gland. Another form of this composite canalicular arrange- ment is when the collection of tubules are more in a line, the branches diverging more slightly from each other (Folliculi com- positi) and each of those branches again diverging into other branches, and so on successively to their last twigs. The mei- bomian glands and the vesiculac seminales are instances of the linear composite follicle or tube having but one set of branches. A lactiferous duct is an example of the composite secreting canal, or tube with a numerous and indefinite succession of finer and finer branches, and, which end finally in club-like dilatations. Some of these secreting canals end in a divarication of branches resembling the flowering ends of the umbelliferous plants. Some of the glands present a species of regularity in the order of division of their secretory canals. The principal trunk of the latter gives off at intervals nearly uniform lateral branches, these branches give off with regularity other branches, and the latter again observe the same disposition. This modification is preserved to a remarkable degree in the pancreas, and is also visible in the salivary glands, the lachrymal, and the mammary. In cases of this kind the lobulated condition is very clear, the lobules being rather feebly held in connexion with the contiguous ones by loose cellular substance, allowing the lobules to be easily separated from each other by drawing at them. The lobules themselves are ulti- mately divisible into granules, (glomeruli or acini) which under 8 ORGANS OF DIGESTION. the application of the microscope are found to be cells aggregated, surrounded by a fine vascular net-work of capillaries, and making the peripheral end of the most minute secreting canals. The trachea with its division into bronchia, bronchioles, final air tubules, and air vesicles at the end of the latter, represents on a large scale the division which is seen in glands on a small one. An unsettled question is, whether these vesicular terminations are in all cases kept distinct, or whether from a defect in their parietes they do not communicate like the air vesicles of the lungs, and have in that way a tubule common to several. In some instances the ulti- mate secretory tubules of those ramified ducts are arranged like coeca around the branches of the latter. Another form of the ramified secreting tube is where there exists no division of the gland into lobules, but it is resolved at once into acini. These acini being formed upon the final divisions of the secretory tube, which rise up in fasciculi, giving a brush like or penicillous appearance. The liver is an example of the above, it being doubtful whether there is any spheroidal enlarge- ment at the free end of the penicilli.* The glands with successively ramified secreting tubes are the Lachrymal gland, Mammary gland, Salivary glands as Parotid, Sublingual, and Submaxillary, Pancreas, Liver. The glands of an almost pure tubular structure and indisposed to ramify, except in a very limited manner, are the Kidneys, Testicles. The Meibomian glands and the Vesicula? seminales may be con- sidered as a tendency to the same structure, but in a more abbre- viated and simple condition, by some they are considered merely as branched follicles. The summary of the secretory glandular system then is for it to present itself in the simple short tubular state of shallow depressions, * From peniculus a painter's pencil. * GLANDS. 9 or crypts of a mucous membrane as in the urethra and bladder;— in bottle-shape cavities;—in closed lenticular cavities, as Peyers's Glands;—as the follicles of the alimentary canal which are either sin- gle or branched;—and as thin follicles with a glandular matter or parenchyma, principally vascular, forming a nidus around them, and which follicles may themselves be either simple or branched in some degree. The principal object of a secreting glandular structure would seem to be a development or augmentation of surface sufficient to the purpose of elaborating the quantity of the specific fluid called for; in other words, for getting area for the requisite ends, like the display of surface in the interior of the lungs for air enough by respiration. They seem, therefore, as said by some, to be a sort of efflorescence from the surface, or cavity upon which they discharge; being formed of canals with closed extremities as origi- nally asserted by Malpighi. It is denied by Miiller* that there are acini in any glands what- ever (the testes of some few fishes excepted) existing, as com- monly understood, to wit, as solid granules executing secretion; by means of their glomeruli of blood vessels having ducts arising from them, in an unexplained way. On the contrary, he asserts, that acini are merely bundles of fine tubes formed by the ends of secreting canals, or frequently by collections of the vesicular termi- nations of the latter. The term acinus in its qualified sense is suf- ficiently proper, but it should be remembered that in receiving it according to its meaning, which is a berry or grape, the skin of the grape and its pedicle are alone to be understood, the pulp being omitted. In regard to the connexion with the blood vessels, their cavities are as stated not to be considered, according to Miiller, as continuous with the cavities of the secreting tubes, but merely ramified on them by countless capillaries, the arteries simply terminating in the veins as in the case of the lungs, or, I may say, of the intestinal canal. This theory is, however, almost too exclusive; there are most pro- bably, organized porosities in the capillary system, I am disposed to think, in the venous especially, forming a communication be- tween the vessels and the canals on which they ramify; it is rather too easy to pass a minute injection from the capillary system into * Physiol, p. 501. 2* 10 ORGANS OF DIGESTION. the canal upon which it ramifies, for us to suppose that every such case is one of rupture. We must, also, upon the ground of per- sonal observation to the contrary, decline the opinion of Professor Miiller, that there is no communication between the secretory ducts and the lymphatics. The cause of the massive character of many glands and of their shape may now be understood. The shape of glands must depend measurably upon the space and circumstances in which they are accommodated, the diversity of shape in the three salivary glands shows that this is a point of merely local convenience, and is subordinate. Their size, however, is upon another ground: this is regulated by the amount of secretion to be done, and by the necessity of this secretion being collected at one or more points. The process of assimilation requires the bile in the duodenum only, and that in large quantity; hence the liver is both a very large organ and all its secretion is concentrated in one focus. If the necessity for the latter had not existed, the liver like the muci- parous glands might have been disposed in small granules all along the alimentary canal. This hypothesis, by the way, will show how the liver or any other gland may exist in the form of insulated acini without the function being altered; and also show the reverse, how if all the muciparous glands were collected into one mass for the purpose of having a focal point of discharge, that this arrange- ment would require also a single large duct made by the succes- sive junction of branches, just as in the liver. As the vascular capillaries ramify upon the parietes of the secre- tory tubes, so, their parent branches are found in company with the larger branches of the latter. The development of the two systems is found to be simultaneous. The tubes are first of all planes, then simple canals or ccEca, then primary branched canals or cceca, then undergoing an indefinite series of divisions. At first these canals are loose and unconnected, but as the evolution of the gland ad- vances they cohere and become consolidated, but at every period of development and of perfection, the capillaries form a net-work around them smaller than the tubes themselves. There is no essential correspondence between the construction of a gland and its secretion. Very different glands have similar structure, as the testes and the kidneys, and similar elands have a varied structure in different animals. The liver in one animal is simply in the form of coeca, in another of tufts of cceca; in others glands'. 11 of branches of cells or of a spongy tissue, or as a branched duct having terminal twigs like a feather. The testes are indefinitely varied; the kidneys alone maintain a constant character. The con- struction of a gland is always regulated by the special demand upon it by the condition of the animal in question, hence the salivary glands are exceedingly simple in birds and serpents; the pancreas in fish, and the liver in the lower animals. Where more surface is required, then new processes from the main line of the secreting tube spring up. Recent microscopic observations have ascertained other new points in glandular structure. Purkinje remarked, that the walls of all secreting cavities, or canals are formed by nucleated granules, making, according to his phraseology, the glandular Enckyma. With the aid of Schwann and Henle this enchyma has been found in all the glands and over the entire mucous sur- face, constituting in fact a cellular nucleated epithelium, which is said to execute the specific function of the gland. The diameter of the nuclei is extremely small, being about the o-or3 3 °f a line.* There are some other organs called glands, but they differ from the preceding in having no excretory ducts. They are supposed to be limited in their function to the modifying in some measure the fluids going through them. One kind of them is formed essen- tially of blood vessels, and they are called ganglia sanguineo-vascu- losa; of these we have the spleen for the chylopoetic system; the capsular renales for the kidneys; the thymus and thyroid gland for the organs of respiration, and the placenta for foetal life. The second kind, called lymphatic glands, (ganglia lymphatico-vascu- losa,) consist essentially of lymphatic vessels entering on one side and departing at the other, after having divided into branches and cells in the thickness of the gland. There are also other glands whose character and functions are still more doubtful, they being found in contiguity with the encephalon, as the Pituitary gland, the Pineal, and the glands of Pacchioni. The real glands on the contrary not only modify the blood which circulates through them, but give rise to a new fluid as a conse- quence of the transformation of the blood; and this new fluid is discharged for a specific purpose by its efferent tubes into con- tiguous canals or places. * MQller, p. 505. 12 ORGANS of digestion. CHAPTER II. Of the Abdomen Generally. The cavity of the abdomen occupies the space between the infe- rior surface of the diaphragm and the outlet of the pelvis; a con- siderable part of it is, therefore, within the periphery of the lower ribs above, and of the pelvis below. It is completely separated from the cavity of the thorax by the diaphragm, with the excep- tion of the foramina in the latter, for transmitting the aorta, the ascending cava, and the oesophagus. It is bounded, below, by the iliaci interni, the psose, and the levatores ani muscles; on the front and sides by the five pairs of muscles called abdominal; and be- hind by the lesser muscle of the diaphragm, the quadrati lumborum, the lumbar vertebrae, and the sacrum. The figure of this cavity is, therefore, too irregular to admit of a very rigid comparison with any of the common objects of life; but a little reflection, on the course of its parietes, will make it perfectly understood. It should be borne in mind, that the very great projection of the lum- bar vertebras forms for it a partial vertical septum behind; which, in thin subjects, is almost in contact with the linea alba in front, and may be easily distinguished through the parietes of the abdo- men, when the intestines are empty. The abdominal cavity varies only, inconsiderably, in its vertical diameter, owing to the resistance of the diaphragm above, and of the pelvis below; neither does it change behind, owing to the re- sistance of the spine, the ribs, and the muscles there. But as the introduction of food, the development of gaseous substances during digestion, the evolution of the foetus, and many other conditions, require some provision for its undergoing an easy augmentation of volume; the latter occurs principally forwards and laterally, by the yielding of the muscles and by the extension of their aponeu- roses. The diaphragm and the abdominal muscles, for the most part, act alternately; as the former descends in inspiration the latter relax and give way to the contents of the abdomen; but in expira- OF THE ABDOMEN. 13 tion, the abdominal muscles contract, and the diaphragm is pushed upwards by the viscera. In attempts at the expulsion of faxes, and in parturition, these muscles contracting, and the diaphragm being fixed all at the same moment, the cavity of the abdomen is actually much diminished. The viscera contained in the cavity of the abdomen are of three kinds. One kind is engaged in digestion and assimilation; another in secretion and excretion of urine; and the third in generation. As these viscera are numerous, and it is of great importance to determine with precision their position and relative situation, ana- tomists are agreed to divide the cavity of the abdomen into several arbitrary regions. This is the more advantageous, as the bony prominences bounding the abdomen are not sufficiently numerous and distinct, to afford those obvious points of relation to the vis- cera which are furnished in other sections of the body. To obtain these regions, consider a line or plane as extending across the ab- domen, about two inches below the umbilicus, from the superior part of the crista of one ilium, as it appears through the skin, to the corresponding place of the other side. Strike on each side a line perpendicular to the preceding, by commencing at the lower end of the anterior inferior spinous process of the ilium, and car- rying it up to the diaphragm. Extend a fourth line across the ab- domen parallel with the first, and intersecting the last two where they come upon the cartilages of the false ribs. It is evident that these four lines or planes, two horizontal and two vertical, will, with the assistance of the parietes of the abdomen, furnish nine re- gions: three above; three in the middle, and three below. The central region, above, is the Epigastric; and on its sides are the right and the left Hypochondriac. The central region in the mid- dle, surrounding the navel, is the Umbilical; and on its sides are the right and the left Lumbar. The central region below, is the Hypogastric; and on its sides are the right and the left Iliac. There are also some subordinate divisions: for example, the hollow in the epigastric region, around the ensiform cartilage, is called the pit of the stomach, or Scrobiculus Cordis; and for an inch or 1 wo around the symphysis pubis, is the region of the pubes, (Regia Pubis.) Anatomists differ among themselves about the points of depar- ture and the position of the lines, or rather planes, separating the regions. Some fix them at definite distances from the umbilicus, 14 ORGANS OF DIGESTION. and others resort to the points of the skeleton. The umbilicus is the most fallacious mark, because its elevation varies considera- bly, according to the state of distention of the abdomen, it being comparatively higher when the abdomen is tumid than when it is not. Neither does it answer to take the anterior ends of the last ribs as the points for the upper horizontal line to pass through; as they, sometimes, are almost as low down as the umbilicus itself. The superior anterior spinous processes are also objectionable as the points of departure for the vertical lines; as they leave too much room for the central regions of the abdomen, and too little for the lateral: I have, therefore, after some hesitation, thought proper to substitute the anterior inferior spinous processes; and, especially, as the position of the viscera, according to almost uni- versal description, is more in accordance with this rule. General Situation of the Viscera of the Abdomen. When the abdomen is so opened as to leave its viscera in their natural position, they will be found as follows:— 1. The Liver, the largest gland of the body, is in the right up- per part of the abdomen, immediately below the diaphragm. It occupies nearly the whole of the right hypochondriac region ; the upper half of the epigastric ; and the right superior part of the left hypochondriac. The anterior extremity of the gall-bladder pro- jects beyond its anterior margin. 2. The spleen is situated in the posterior part of the left hypo- chondriac region. 3. The stomach, in a moderate condition of distention, occupies the lower half of the epigastric region, and the right inferior por- tion of the left hypochondriac. 4. The Small Intestine, when moderately distended by flatus, occupies the umbilical region, the hypogastric, portions of the iliac on each side, and also the upper part of the cavity of the pelvis, when the viscera of the latter are empty. 5. The Large Intestine traverses the cavity of the abdomen in OF THE ABDOMEN. 15 such manner as to perform almost the entire circuit of it. It be- gins in the right iliac region by receiving the lower extremity of the small intestine; it then ascends through the right lumbar and the right hypochondriac, passes into the lower part of the epigas- tric, or into the upper of the umbilical, according to the state of distention of the stomach; thence it gets into the left hypochon- driac, being fixed higher up there than in the corresponding region of the other side; afterwards it goes down into the left lumbar and into the left iliac; thence it passes into the pelvis, and, de- scending in front of the sacrum, terminates in the orifice called anus. 6. The Caul, or Omentum, is a membrane, of various densities, in different individuals, and lies in front of the intestines. Some- times it is found spread over the latter like an apron, but on other occasions is dr,awn up into the umbilical region, forming a ridge across it. It is attached to the stomach and large intestine. 7. The Pancreas lies transversely in the lower back part of the epigastric region. It extends from the left hypochondriac region to the right side of the spine, and is placed behind the stomach, so as to be covered by it. 8. The Kidneys and the Capsular Renales, two in number each, are placed in the posterior part of the lumbar region on the side of the spine. 9. The Urinary Bladder and the Rectum, in the male, occupy the cavity of the pelvis, and in the female between them are placed the uterus, the ovaries, and the vagina. As, in the dissection of the abdominal viscera, the subject is commonly placed on its back, so the preceding description is made out with a strict reference to that position. Some modifi- cation in the shape of the abdomen, as well as in the situation of its contents, occurs in standing upright. The front of the abdo- men becomes then more protuberant, the lumbar vertebras make a greater projection forwards. The pelvis is then so adjusted, in order to bring the acetabula directly in the line of support to the spine, that the convexity of the sacrum presents almost upwards, and the 10 ORGANS OF DIGESTION. superior strait looks forwards and upwards towards the navel, so that much of the weight of the viscera is thrown upon the pubes. In this attitude most of the viscera descend, but more obviously the liver, from its weight, size, and solidity. Portal has verified this descent by comparing the thrusts of poniards into the liver in the erect, with those inflicted in the horizontal position. He also asserts that the same may be ascertained in the living body by ap- plying the fingers under the false ribs, and then directing the per- son to change from the recumbent into the vertical position. The spleen affords the same results when it is slightly enlarged, and the descent of the liver and spleen will of course ensure that of the stomach and intestines. According to Winslow. the pain and faintness which are felt after a long abstinence, come from the vacuity of the stomach and intestines, which thereby withdraw their support from the liver, and permit it to drag upon the dia- phragm. The presence of flatus in the stomach and intestinal canal, seems to be entirely natural to them ; for it is comparatively rare to find them destitute of it, even when they contain no food or faeces. The large intestine is, however, more frequently found contracted or empty than the small. Owing to the flexible cha- racter of a considerable portion of the abdominal parietes, the lat- ter, by their own contraction, as well as by atmospheric pressure, are kept in close contact with the viscera; and the viscera again, by the same influence, are kept in close contact with one another; so that, notwithstanding the irregularity of their forms and the fluctu* ating size of the hollow ones, there is no unoccupied space in the cavity of the belly. Several instances are reported by anatomists, in which a total transposition of the abdominal viscera, has occurred, so that those which belonged to the right side were placed in the left.* They are, however, exceedingly rare. In the entire observation of my life, amounting to thirty years of anatomical study, and extending itself to many hundred bodies, I have not met with one instance of it. * Portal, Haller, Sandifort, &o. OF THE PERITONEUM. 17 CHAPTER III. Of the Peritoneum, and Serous Membranes, Generally. SECT. I.—OF THE PERITONEUM. The sides of the abdomen are lined, and its viscera are covered by a membrane called Peritoneum. As the reflections of this membrane, by being thrown over the periphery of almost every viscus of the abdomen, consequently, assume the same shape; and as it lines, without exception, the interior surface of every part of the abdomen, its form is extremely complicated, and can only be judged of accurately after the study of the viscera is completed. For the present it will only be necessary to give the outline of it, leaving the details to each appropriate occasion. In man, it is a complete sac, having no hole in it; but in wo- man, its cavity communicates externally through the Fallopian tubes. It has a double use : In consequence of covering the vis- cera, it is so reflected from them to the sides of the abdomen, that its processes keep the viscera in their proper places, and, there- fore, answer as ligaments: again, its internal surface being smooth, indeed, highly polished, and continually lubricated by a thin, albu- minous fluid, corresponding with the synovial membrane of the joints, the motions which the viscera have upon each other in ex- ercise, and in the peristaltic action of the bowels, are much facili- tated. The manner in which a double night-cap is applied to the head. will afford the easiest conception of the reflections of the perito- neum. If there were only one viscus in the belly, and that of a somewhat regular outline, as the spleen, the comparison would be rigid, and perfectly appreciable. One part of the cap is close to the head, and compares with the peritoneal coat of the spleen; the other is loose, and is equivalent to the peritoneum, where it is in contact with the parietes of the belly. It is also evident from this, that none of the viscera can be said to be within the cavity of the peritoneum'; that they are all on its outside; and that a viscus, in Vol. II.—3 18 ORGANS OF DIGESTION. getting a coat from the peritoneum, merely makes a protrusion into its cavity. Starting with this simple proposition, it is easy to conceive of a second, a third body, and so on, deriving an external coat from a protrusion into the same sac. Admitting these bodies to be spheres, the proposition is immediately intelligible; and, as a last step from it, the idea is not rendered much more complex by substituting any bodies even the most irregular in form, for these spheres. Such, then, is the fact in regard to the stomach, intestines, &c.; they all, with the exceptions to be stated, derive an external coat from the peritoneum. The Peritoneum is, for the most part, smoothly spread upon the interior surface of the abdominal muscles. It adheres to them with considerable firmness by means of intervening cellular sub- stance: this adhesion, where it closes the posterior opening of the umbilicus, is unusually strong. Below, the uniformity of the mem- brane as it descends from the navel to the pelvis is interrupted by its being reflected over the urachus, and over the remains of the umbilical artery on each side. Where the urachus is, it forms an oblong prominent ridge, reaching to the upper extremity of the bladder; and, as regards each umbilical artery, the duplicature is of a variable breadth in different individuals; but always forms a well marked falciform process, reaching from near the umbilicus to the lower side of the bladder, and dividing the inguinal region into two parts or fossae, one next to the pubes, and the other near to the ilium. In the undistended state of the bladder the perito- neum reaches to the pubes, is reflected from the latter to the upper, and then goes over the posterior surface of the bladder. In the male, it goes from the posterior lower end of the bladder to the rectum, but, in the female it does not descend so low there, and passes from the bladder to the vagina and uterus, and afterwards to the rectum. In the concavity of the ilium, and in the lumbar region, the peri- toneum is attached by long loose cellular substance, which permits it to be stripped off easily, simply by tearing. In these several regions it encounters the colon, over which it is reflected, and thereby forms the Mesocolon; thence it passes in front of the kid- neys, but separated from them by a thick layer of cellular and adipose matter, and immediately afterwards it is thrown into a long duplicature, extending obliquely across the lumbar vertebrae OF THE OMENTA. 19 from above, downwards, and to the right side. This duplicature includes the small intestine, and is the Mesentery. In the highest regions of the abdomen, the peritoneum is in the greater part of its extent uniformly reflected over the concave sur- face of the diaphragm, and adheres so closely to it, as to require a cautious and protracted dissection for its entire removal. As the remains of the umbilical vein of the foetus are still found, but in a ligamentous condition, going from the navel to the under surface of the liver, their existence gives rise to the falciform ligament, a broad duplicature of peritoneum, which passes from the upper half of the linea alba and from the middle line of the diaphragm to the liver. Another line of attachment, or of reflection, of this mem- brane to the liver, is found all along the posterior margin of the latter. In the same region, it is also reflected from the diaphragm to the spleen and to the stomach. Such is the general account of the course of the peritoneum. Each of the duplications has a dis- tinct name, and some peculiarity of organization or of relation, which will require a specific description and a frequent allusion to it. It is proved, from what has been said., that the peritoneum is a single and complete sac, and that, with the exception stated of the Fallopian tubes, there is no hole in it either for the passing of blood vessels, nerves, or viscera. And that it is so folded over the abdo- minal viscera, that with patience and sufficient address, one might remove it from their surface and extract them, without even laying open its cavity: an experiment said to have been successfully ac- complished by Nicholas Massa,* and some other anatomists. SECT. II.—OF THE OMENTA.. There are four processes of the peritoneum, each of which is designated under the term Omentum, Epiploon, or Caul. 1. The Omentum Minus or Hepatico-Gastricum, extends, as its name imports, between the liver and the stomach. It begins at the transverse fissure of the liver, and proceeds from it, from the right side of the lobulus spigelii, the front of which it conceals, * Anat. Liber. Introduct. an. 1539. Portal. 20 ORGANS OF DIGESTION. and from the inferior posterior face of the tendinous centre of the diaphragm; it is attached to the lesser curvature of the stomach in all the space between the cardiac and the pyloric orifice. Its right margin reaches beyond the pylorus to the duodenum, and includes the vessels going to the liver, and the biliary ducts; in consequence of which, this margin is called the Capsule of Glisson. The capsule is, however, more properly the condensed cellular substance within. The two laminae which compose the omentum minus are thin and transparent, and have but little fat in them; in approaching the stomach they become very distinct from each other, and re- ceive between them the superior coronary vessels of the stomach. One lamina then goes before the stomach and the other behind, in the form of a peritoneal covering. These laminae, having covered in that way the anterior and the posterior surface of the stomach, unite again on the greater curvature of the latter, to form the be- ginning of the omentum majus. 2. The Omentum Majus or Gastro-Colicum, as indicated by its name, is connected at one end all along the greater curvature of the stomach, and by the other along the transverse part of the colon. As it commences by two laminae, so it is continued through- out in the same way. It is commonly found more or less spread on the front surface of the small intestines, but occasionally it is tucked up in the epigastric region. When fairly spread out, either naturally or artificially, its course will be found as follows: It first of all descends from the stomach to the pelvis ; it then turns up- wards, so as to reverse its course, and continues to ascend till it reaches the colon. Its two laminae then separate and receive the colon between them, so that, in this respect, the arrangement is entirely conformable to what happens to the stomach. The sub- sequent continuation of these laminae is the mesocolon, which will be more particularly described. As the omentum majus consists of two laminae in its whole ex- tent, it is clear that it resembles a flattened bag lined by another bag; so that in its whole thickness, when held between the fingers, there are four laminae. It is an irregular quadrilateral membrane, which, in corpulent subjects, is interspersed with a great deal of fat; but in such as are emaciated, it is wholly destitute of the lat- ter ; and instead of being entire in its parietes is a delicate reticu- OF THE OMENTA. 21 lated membrane, so that the rule about the integrity of the perito- neum is not fully accurate as applied to this section of it. On the right side it is continuous with the omentum colicum, and on the left with the omentum gastro-splenicum. 3. The Omentum Colicum may be considered as a continuation of the omentum majus along the ascending and a part of the trans- verse colon. In some rare cases, (for in my own observations I have not met with the arrangement,) its origin is continued down- wards to the ccecum, and at its left margin is extended along the transverse colon to the spleen. Much more commonly it is, as stated, simply an appendage of the great omentum, or its right flank, advancing for a short distance along the ascending colon. It consists of but two laminae in all, commonly containing fat, but in this respect subject to the same rule as the omentum majus. 4. The Omentum Gastro Splenicum is the left flank or margin of the omentum majus, extended from the great end of the stomach to the spleen. It of course consists of but two laminae, which con- tain between them the splenic vessels and the vasa brevia. By looking for the posterior end of the gall-bladder, and then passing a finger under the right margin of the hepatico-gastric omentum, or in other words, under the capsule of Glisson, where it extends from the liver to the duodenum, the finger will be found to have insinuated itself behind the stomach, and, by being directed downwards, will be thrust into the sac or cavity of the great omentum. In children, where the latter is less reticulated than in adults, and consequently more entire, a large blow-pipe intro- duced at the same point will enable one to inflate this cavity, and to separate its anterior from its posterior wall. This aperture, called the foramen of Winslow, is the route by which the internal or lining lamina of the omentum majus is introduced, so as to make this process of peritoneum double throughout its whole parietes. Though this fact of duplicity is generally conceded, no author heretofore, to my knowledge, has pointed out satisfactorily the means; and for the suggestion of it, I am indebted to a learned and zealous member of the profession, now Professor Hodge of the University. Struck, at an early period of his studies, with the difficulty of tracing a double sac to the omentum majus, out of a single- membrane of the peritoneum, this suggestion was happily 22 ORGANS OF DIGESTION. made by him to remove the difficulties of other explanations. An attempt at a diagram formed upon any other principle I have in- variably seen to fail. If the reader has conceived the idea, the inference will be plain, that the lining lamina of the omentum majus is continued as a common peritoneal covering over the pos- terior face of the stomach, and then forms the posterior lamina of the hepatico-gastric omentum. It will also be plain that the same lamina, having reached the colon in its return, continues after- wards as the upper lamina of the transverse mesocolon. From what has been said concerning the general qualities of the peritoneum, it is to be understood that though it enjoys much power of gradual extension, nevertheless this quality is not suffi- cient to enable it to endure, without a special provision, the sudden and extensive dilatations to which the stomach and bowels are exposed, from the introduction of food and from the evolution of » gases during digestion. Of all the coats of these organs, it is the least extensible and contractile; its rupture, therefore, is guarded against by one invariable rule. For example: as the muscular and other coats of the stomach dilate, the peritoneum is drawn from the omentum minus and majus to cover the stomach; there- fore, as the stomach enlarges, the omenta diminish: and as the stomach decreases, the omenta, by the restoration of peritoneum, resume their primitive size. In this way the uterus, notwithstand- ing its great augmentation in the progress of pregnancy, still keeps itself covered by peritoneum, from the ability of the latter, as men- tioned, to slide from one part and to apply itself to another. The true intention, then, of the apparently useless length of many pro- cesses of the peritoneum, is explained, by their being a provision for the augmentation of the hollow viscera of the abdomen, in the discharge of their natural functions. Adopting this explanation as the basis of our observations, we shall find that according to the probable or even possible augmentation of a viscus, so are its peritoneal attachments. The stomach, which next to the uterus enlarges more than any other viscus, gets its subsidiary supply of peritoneum from the length of the omentum minus and majus; the colon, which is next in order, is supplied from the length of its mesocolon; the small intestines, which are next, from the length of the mesentery. The latter, however, would be too long for that simple purpose; but the objection is removed by recollecting that the mesentery has also to accommodate numerous chains of OF THE OMENTA. 23 lacteal glands, through which the chyle must pass in its elabora- tion, before it is fit to enter into the general circulation. The liver, being of a size almost stationary, has its peritoneal attach- ments proportionally short; and its peritoneal covering, from the shortness of the connecting cellular substance, is disqualified from sliding. The spleen is in the same predicament with the liver, except that its size is not stationary; but, in this case, the perito- neum presents a phenomenon entirely remarkable: it wrinkles upon the contraction of the spleen. If this mode of reasoning, derived, from an arrangement of parts which no one denies, be correct, it follows that physiologists have erred sadly in the supposed uses of the omentum majus. That this organ is, in fact, only subsidiary to the enlargement of the stomach and colon, so as to prevent the rupture of their peritoneal coat, and that it is neither intended to keep the belly warm, as so learned a naturalist as M. G. Cuvier has suggested,* nor is it a special store-house for the wants of the system during the destitu- tion of other aliment, farther than adipose matter in other parts of the body is.f In regard to the first theory, it does not appear that the inhabitants of cold climates are better furnished with an omen- tum majus than those of the torrid zone: that it is better developed in winter than it is in summer; that it is tucked up in warm weather to cool the intestines, or spread out in cold weather to make them more comfortable. On the contrary, it is ascertained that its position is variable at all seasons; that in the coldest of weather it is as often found collected in the epigastric region, or to one side of the abdomen, as it is in the warmest; consequently, its position is the result of whatever motions may, for the time, have been impressed upon it by the distention of the stomach, and by the peristaltic movements of the bowels. In regard to the theory of Dr. Rush, the objection is insurmountable, that children, who are equally, if not more exposed to starvation and sickness than adults, never have fat, except in very small quantities, in the omentum, and that only along the course of its vessels. The fat is, therefore, not to be viewed as an essential circumstance in the structure of the omentum, as all children and many adults have it only very sparingly; for the omentum, being wanted as a mem-. * XXII. Legon D'Anat. Comp. t An Inquiry into, the Uses of the Omentum, by James Rush, Philad. 1809. 24 ORGANS OF DIGESTION. brane of reserve to the stomach and colon, the deposite of fat in it, is in obedience to one of the general laws of the system, whereby the cellular substance beneath the serous membranes is disposed to secrete fat as the individual advances in life; which is exempli- fied on the heart and in the pleura. Another argument is, that in the ruminating animals, where there are four stomachs, and from the vegetable nature of their aliment these stomachs must, in the course of digestion, be very much distended, the great omentum is of proportionate magnitude.* As occurs in other parts of the body, also, the fat of the omen- tum accumulates in animals that take but little exercise, while it is very deficient in such as lead an active life. I am induced to believe that the hard knots felt in the abdomen of such persons as suffer from abdominal affections, frequently de- pend upon the accumulations of the omentum majus at particular but variable points. SECT. III.—GENERAL ANATOMY OF THE SEROUS MEMBRANES. As the peritoneum presents one of the best examples of a nume- rous class of membranes, called Serous, it will be useful at this point to inquire into their general condition and properties. Thev are, for the most part, thin, and strongly resemble compressed cel- lular membrane; having been, indeed, by some anatomists, con- sidered as such. They invariably assume the form of perfect sacs, and as they are found in all parts of the body, they are kept dis- tinct from each other. The arachnoid membrane of the brain, the pericardium, the pleura, the synovial membranes of the joints, the bursae mucosas of tendons, the peritoneum, and the tunica vaginalis testis, belong to this class. They are not all of the same thickness, as some are much more dense than others; they adhere to neigh- bouring parts by a lamina of cellular substance, which is also of variable thickness and ductility; indeed, on some occasions, it is not entirely distinct, from its extreme shortness and tenuity. As the serous membranes are only displayed over the surface of the organs which they cover, after the manner of a double night- cap drawn over the head; their cavity always remains entire, not- * Cuvier, XXII. Lejon, loc. cit. ANATOMY OF SEROUS MEMBRANES. 25 withstanding it is variously modified by the shape of the organs protruded into it; and has its parietes in contact, owing to external compression. They are entirely distinct from the essential struc- ture of the organs covered, and are displayed over those of the most dissimilar functions, as, for example, the intestines and the liver. A sac of this description, then, is of infinite importance in establishing between organs which border upon one another a strong partition: and, consequently, in warding off any injurious influence which their dissimilar natures would otherwise cause them to have upon each other. Important organs are, therefore, invariably thus insulated, so that whether in a healthy or in a dis- eased state, their actions are carried on within themselves; and not only so, but it is even possible, and, indeed, is found in morbid dissections, every day, that an organ may be diseased while its serous covering is unaffected; or the reverse. Thus, we have large suppurations in the liver, while its peritoneal coat is healthy; large accumulations of water in the ,tunica vaginalis testis, while the testicle itself is sound; in the thorax, with sound lungs and heart; in the abdomen, with viscera generally sound; in the joints, without an affection of the bones. Nothing is more common than to see partial adhesions, the result of inflammation, causing the opposite sides of these sacs to adhere, without any evident consti- tutional or visceral derangement; and some of our plans of cure, as in the hydrocele, are founded upon this well established fact. The serous membranes are throughout thin, transparent, and white: in some points their tenuity is so extreme that they seem to consist simply in a smooth, polished surface, spread over parts; this is strikingly the case on the interior face of the dura mater, on the ventricles of the brain, and on the cartilages of the joints. The evidence of their extension there, is consequently derived principally from induction; and from morbid alteration, in which they become thickened. Their internal surface in a natural state, is always smooth, highly polished, shining; and, being also lubri- cated by its peculiar unctuous secretion, the opposite parietes, when they come into contact, glide freely upon each other; a cir- cumstance indispensable to the free action of the joints, and to the peristaltic motion of the bowels. Bordeu has asserted, that these remarkable characters of the serous membranes depend upon the compression and the friction to which they are continually exposed: but to this opinion the argument of Bichat is unanswerable, that 26 ORGANS OF DIGESTION. in their earliest observable period in the foetus they have the same polish. The fluid secreted from the serous membranes resembles, strongly, the serosity of the blood. It is poured out continually by the exhalent orifices, and in a short time afterwards is taken up by the absorbents; so that in a natural state there is seldom more than sufficient to lubricate the surface of the membrane. When the abdomen of an animal recently killed is exposed to the air, this fluid rises in the form of a vapour. The several experi- ments, as the application of heat, mineral acids, and so on, which prove the abundance of albumen in the serum of the blood, pro- duce the same results when applied to the secretion from the serous membranes. The system of serous membranes has been considered by Bichat and others, as only a modification of cellular membrane, for the following reasons. The inflation of air into the cellular tissue sub- jacent to them, reduces them to the form of cellular substance. Protracted maceration produces the same effects with more cer- tainty and precision. When cellular membrane is inflated, the parietes of the distended cells resemble strongly the finest parts of the serous system, as the arachnoid membrane. There is an identity of functions and of affections, for they are both conti- nually engaged in the great work of exhalation and absorption, and suffer in the same way from dropsical effusion, with the only difference that the latter is more amassed in the one than in the other. My own experience goes to prove, that dropsy very sel- dom manifests itself, to any extent, in the cellular tissue without also going to the serous cavities, and the reverse. The serous membranes are also of a uniform texture, like cellular substance, and present no appearance of a fibrous matter. The serous membranes are furnished with a great abundance of exhalent pores, and of absorbents, which carry on their func- tions with great activity. They, when healthy, receive only the colourless part of the blood, whence the uniform transparency of these membranes. The existence of exhalent pores, is proved by strangulating a piece of intestine with a ligature for thirty-six or forty-eight hours, when they become evident, by dilating them- selves so as to receive red blood. A fine coloured injection pro- duces the same result; and also moistens, by the escape of its watery particles, the surface of the intestine, by a very fine halitus ANATOMY OF SEROUS MEMBRANES. 27 or dew. The intestine of a living animal, if wiped perfectly dry, will, after the same way, soon present another coat of serosity on its surface. The existence of absorbents to a great extent in them, may also be equally well proved, as they very readily receive a mercurial injection, which diffuses itself over their whole surface, and causes them to have the appearance of being formed entirely of such vessels. The readiness with which fluid effused into their cavities is taken up, is another proof of the same. Bichat once saw them distended with air in a man who had become emphyse- matous from poisoning. Mascagni has frequently found them dis- tended with the fluid of dropsical collections, which he recognised by its colour. It happened to the same anatomist to find in two bodies, where there had been an effusion of blood into the thorax, the absorbents of the lungs gorged with blood. This faculty of absorption may sometimes be proved to continue for some hours after death, by keeping an animal in a warm bath. Mascagni asserts, that he has witnessed its continuance for fifteen, thirty, and even for forty-eight hours; it is not improbable, however, that there was some illusion in these instances. It is more than probable that the serous membranes are entirely deprived of red blood vessels; the latter unquestionably exist, in great numbers, on the exterior surface, where they creep through the cellular substance, but they may be removed with a scalpel without affecting the continuity of these membranes. Again, where these membranes are free and unconnected oh both sur- faces, as in some parts of the tunica arachnoidea, there is no ap- pearance of red blood vessels. In hernial protrusions, where there is a considerable prolapse of peritoneum, the blood vessels which are found abundantly about the neck of the sac do not follow the course of the protrusion. Unquestionably some communication exists between the arterial system and the serous membranes, as proved by exhalation and morbid phenomena, but the mode is not well ascertained. We learn, however, upon the authority of Miil- ler,* that there are some preparations of the peritoneum by Bleu- land at Utrecht, leading to a different conclusion—and that there are some also by Der Kolk, of the same membrane, which prove indubitably that this membrane contains vessels. In common hernia and in dropsy, the serous membranes become Phys. p. 226. 28 ORGANS OF DIGESTION. more thick: from my dissections I am inclined to think, that this change is not so great as is generally allowed; for most frequently, by a careful removal of the exterior cellular substance, they have been restored to their primitive condition. In other cases, as in large umbilical herniae, they are so much attenuated as to be found with difficulty. The power of extension which these membranes possess, is strikingly marked in dropsical effusions, in the development of tumours, and in pregnancy; but much of this apparent quality is derived from their mode of attachment to adjacent parts, whereby they are drawn from one surface to cover another. This happens daily where the peritoneum is drawn from the lower part of the abdomen to cover the bladder in the distentions of the latter; in pregnancy, where it is drawn upon the growing uterus from all the neighbouring parts; and in the distentions of the stomach by food or flatus, where it is drawn up from the omenta. The serous membranes have also a power of contraction equal to that of their extension; but it should not be confounded with that condition where they are simply restored by the connecting cellular sub- stance, to the surfaces to which they originally belonged. The sensibility of the serous membranes, from the want of nerves in them, is extremely obscure in a natural state, and only affords an imperfect sensation of touch. This is proved by the impunity with which they may be irritated on living animals. But, when the condition of inflammation is once established, they feel the most acute and distressing pain. Though they resist most frequently, and for a long time, disease in adjacent parts, yet it not unfrequently is extended to them at last. In such cases, it is generally a local instead of a universal affection, which is com- municated to them: Thus, in the cancer and scirrhus of the uterus; in disease of the spleen, and so on; the portion of peritoneum nearest the affected organ manifests the marks of the disease by preterna- turaladhesions and by disorganization, without the whole mem- brane being involved. As the serous system consists in many species of sacs, so each of them has some peculiarity of organization, of attachment, and of vital properties, which is stated elsewhere in the account of the species themselves. The microscope has proved that notwithstanding the extremely polished surface of the free side of the serous membranes, yet they THE STOMACH. 29 are covered by an epithelium. This epithelium has been found on all except the subcutaneous bursas. The epithelium of the serous cavities is, like the epidermis, formed of flattened scale-like cells, which are, for the most part, polygonal or tesselated, like a pave- ment made of hexagonal bricks, and have each a nucleus in their centre. Some of these cells are furnished at their edges with minute hair-like filaments called cilia, which, during life and for some time after death, are in a state of continual whirling or vibration, and as is supposed, for the purpose of preventing a stagnation of the fluids in contact with them. These cilia are especially numerous and active in the ventricles of the brain. In some places the epithelium is found without the serous mem- brane beneath, hence it is inferred that the latter is not so essen- tial as the former in the character of such membranes. Epithelia being always in contact with fluids, they differ from the cuticle in being pliant and humid, but are restored with equal facility when they are lost by abrasion or inflammation. CHAPTER IV. Of the Chylopoetic Viscera. SECT. I.—OF THE STOMACH. The Stomach (Ventriculus, Stomachus) is a hollow viscus situ- ated in the epigastric region, intended to receive at one end ali- mentary matters from the oesophagus, and to transmit them, at its other extremity, after digestion, into the intestinal tube, where the nutritious part of the food is absorbed into the circulation. It is a conoidal sac, curved considerably upwards, and presents two Faces, two Orifices, two Curvatures, and two Extremities. The Faces of the stomach are, from their position, named ante- rior and posterior, or, one presents to the linea alba and the other towards the spine. The flat configuration is rendered more ob- vious when the organ is empty; for when distended it is rounded, Vol. II.—4 30 ORGANS OF DIGESTION. and the anterior face is caused to look forwards and upwards from the resistance of the spine behind, while the posterior is of course in an opposite direction. In other respects they do not present any thing worthy of particular attention.* The two Orifices of the stomach are named Cardia and Pylorus. The first or Cardia is at the left and most superior part, but re- moved to the distance of two inches or more from the left extre- mity. It is generally considered a smooth uninterrupted continua- tion of the oesophagus into the stomach, immediately after the oesophagus has passed through the diaphragm into the abdomen. But in a preparation,! of this organ, made by drying, and now in the anatomical cabinet, a circular rounded pad is very perceptible at the cardiac orifice; being elevated two lines or more all round, so that it makes a perfect ring of from eight to twelve lines broad at its base. This pad seems to be composed of a cellular sub- stance, which is almost perfectly white, elastic, and consists of the finest filaments, resembling carded cotton: it is placed between the lining membrane of the cardiac orifice and the adjoining coat. The Pylorus, when viewed externally, looks like a smooth con- tinuation of the stomach into the duodenum; but when felt, there is a manifest thickening of the part, depending upon a structure to be presently explained. It points upwards and to the left side, but is, by the whole thickness of the liver, lower down than the cardia. The two Curvatures are designated the great and small, or the upper and the lower. The first, forming the upper margin of the stomach, is bounded at its extremities by the orifices, and is very concave; its curvature is maintained both by a natural configura- tion and by the small omentum. The great curvature forms the whole inferior periphery of the organ, extending also from one orifice to the other. When the stomach is flattened, these curva- tures form very evident boundaries to the anterior and the poste- rior faces. The Extremities of this organ are singularly different in size. That on the left forms the base of the cone, or the large extremity, and projects considerably beyond the cardia towards the spleen. * In some cases the posterior face of the stomach is concave to accommodate it to the spine: this is best seen on inflation and drying. t Made December, 1828. THE STOMACH. 31 It is a rounded cul-de-sac, or tuberosity, the dimensions of which will, of course, vary according to the state of distention. The right extremity, on the contrary, is produced by a gradual diminu- tion of the organ from its middle to the duodenum. When the stomach has approached within an inch or two of the latter, it suffers a sort of constriction, which gives to the right end a more cylindrical shape. This part is sometimes called the Little cul-de- sac, or the Antrum pylori. Where the stomach has been kept empty for some time pre- viously to death, it is found not much larger than an intestine; its variable magnitude, therefore, prevents any very rigid rule of di- mensions from being applied to it; most commonly, however, we find it between the capaciousness of a pint and a quart measure. It is retained in its situation by its continuity with the oesophagus and duodenum ; also by the hepatico-gastric, and the gastro-splenic omentum. It is in contact above, at its lesser curvature, with the diaphragm, the left lobe of the liver, and the lobulus Spigelii; at its great extremity with the spleen, at its posterior face with the pan- creas, and at its greater curvature with the colon and the meso- colon. The stomach is formed by four Coats or laminae, of a character essentially differing from each other: The Peritoneal, the Muscular, the Nervous, and the Mucous. The Peritoneal Coat envelops the stomach completely, and ad- heres closely, except at the curvatures, where, as has been men- tioned, a provision is made for the distention of the organ, by the looseness and the separability of the attachment of the two laminae of the omentum minus and of the majus. An uncovered space will, consequently, be found between the lamina? at these places, along which the vessels run that furnish the stomach. The peri- toneal coat is very thin, and is attached to the subjacent muscular, by very fine cellular substance, which permits it to be raised from the muscular by a careful dissection. In a dried preparation which I made,* there is an exhibition of minute foramina of the peritoneal coat, in apposition as close as the follicles of the mucous coat. The Muscular Coat is intermediate in thickness to that of the intestines and of the oesophagus, but its fibres are pale, are col- lected into flattened fasciculi, and go in three directions. The * In 1839. 32 ORGANS OF DIGESTION. most superficial are a continuation of the longitudinal fibres of the oesophagus, and are less numerous and less uniform in their distri- bution than the circular fibres. The greater part of them forms a flattened broad fasciculus, which extends along the lesser curva- ture of the stomach, from the cardiac to the pyloric orifice. A thinner and less distinct fasciculus may be traced over the great cul-de-sac, and somewhat indistinctly, along the greater curva- ture; and a few others may be seen on the anterior and posterior faces of the stomach, forming rather a fine linear or striated appearance than a perfect lamina; this linear appearance is well exhibited by an oblique reflection of light from it. The second series consists in a lamina of circular fibres distinctly covering the whole surface of the organ. They are not so numerous near the cardia, but become more abundant as they are examined towards the pylorus, in the vicinity of which they are multiplied so as to form a lamina of two lines or more in thickness. The circular fibres are parallel with each other, and, when the stomach is much distended, their fasciculi separate so as to leave interstices between them in many places. The individual fibres do not surround en- tirely the stomach, but are rather segments of circles. The third and deepest series of fibres, constituting the muscle of Gavard, from their discoverer, may be called oblique, and are arranged into two broad flattened fasciculi, one of which is placed to the left side of the cardia, and is prolonged over the anterior and the pos- terior faces of the stomach; while the other, being to the right of the same orifice, is extended over the anterior and the posterior faces of the cul-de-sac, where it supplies the want of transverse or circular fibres: this series may be considered as a continuation of the circular fibres of the oesophagus. The Nervous or Cellular Coat (Tunica Propria) connects the muscular with the mucous. It is formed by a compact, thick, and short cellular substance, which, when inflated and dried, looks like carded cotton. It contributes much to the general strength of the organ, and serves to conduct the blood vessels and the nerves to the mucous coat. The Mucous or Villous Coat is the most internal, is not quite a line in thickness, and can be readily raised up by dissection. In an undistended state of the stomach it is arranged into a number of wrinkles, which are very irregular in their form, size, and direc- tion, but disappear immediately on distention, or at least leave but THE STOMACH. 33 very faint traces. It is continuous with the internal membrane of the oesophagus and of the duodenum, but presents a surface differ- ing from either of them, and which is rendered very apparent by floating it in water. The epidermis, which is continued along the internal face of the oesophagus, ceases as mentioned around the cardiac orifice, and, by a slight maceration, may be raised up and demonstrated to terminate there. An epithelium under modified circumstances is then found to start and to cover the entire inte- rior of the stomach, and to be continued over the intestinal canal from one end to the other. It is softer, thinner, and more spongy than the common epidermis of the pharynx and oesophagus, but may be proved to exist by the microscope, by the exfoliations in scales formed in the fasces, and also by insufflation, when it will be raised and may be dried in that state. This mucous membrane or coat, the office of which is to secrete the gastric juice for the digestion of articles of food, presents a surface that resembles very much common velvet, from whence the term villous is applied to it. If it be perfectly healthy, and the individual died suddenly a few hours after eating—it is found of a uniform light pink colour, without blotches or any thing of extravasation under it. This fact I have had several opportunities of verifying, by experiment and by autopsies :* And more lately in the person of a criminal, Williams, executed for murder.f It is usual, to find it, if examined a short time after death, having, particularly along the smaller curvature and at the great end, a pink and sometimes a deeper colour, produced by an accumulation of blood in its veins. The texture of this membrane is soft, loose, and easily lacerated. When floated in water and examined with a magnifying glass, it is found to have a superficial honey-comb arrangement, and to be studded with a multitude of small follicles or orifices. In the vicinity of the cardiac and of the pyloric orifice, the same arrange- ment is more obvious, and conducts to some small muciparous glands, which are more or less apparent, and called the glands of Brunner. At the junction of the lesser extremity of the stomach with the * See Amer. Journal Med. Sciences, Vol. 1. 1827. Horner's Pathol, Anat. p. 195, &c. t Aug. 9, 1839. 4* 34 ORGANS OF DIGESTION. duodenum, the internal membrane is thrown into a circular dupli- cature constituting the Pyloric valve, and abridging the size of the orifice. It is seen most favourably in the distended and dried state, and then presents a sort of septum not unlike the form of the iris. Around the external periphery of this ring, the circular mus- cular fibres have a sudden augmentation of number, which gives them, when viewed from the duodenum, the appearance of a dis- tinct circular muscle, occasionally called the muscle of the pylorus, but it does not exist in a state so separate as this name indicates. The opening of the pyloric valve is generally circular, but some- times ovoidal, and it is sometimes to one side. It is very common to find the stomach divided as it were into two compartments, by a contraction of its middle, resembling that of an hour glass. It is said that this occurs habitually during digestion; in my personal observations, however, I have seen the stomach more frequently in this state when it contained nothing, not even air, than when articles of aliment were in it. The stomach is extremely vascular. Its arteries, being branches of the Coeliac; are the Gastric, the Right, and the Left Gastro- Epiploic, and the Vasa Brevia. The first goes along its lesser curvature, the second and the third along its greater curvature, and the last, from four to six in number, go to its great cul-de-sac. They all approach it between the laminae of its omenta, and un- dergo many divisions and subdivisions in the cellular coat; they at length terminate by forming a very fine and delicate vascular arrangement in the substance of the mucous membrane, and when successfully injected give to the latter a thorough tinge of red. The veins follow the course of the arteries, and like them have frequent anastomoses, but are larger; they terminate either directly or indirectly in the trunk of the Vena Portarum. The nerves of the stomach come from the Par Vagum, and from the semi-lunar ganglions of the Sympathelics. Its lymphatics arise from both the external and the internal sur- face, and their trunks having to pass first of all to the lymphatic glands situated along the curvatures, afterwards empty into the thoracic duct. INTESTINAL CANAL. 35 SECT. II.—OF THE INTESTINAL CANAL. The Intestinal Canal is from thirty to thirty-five feet in length, and extends from the pylorus to the anus. Owing principally to a well marked difference in magnitude, it is divided by anatomists into the Small and into the Large intestine. Of the Small Intestine. The Small Intestine (Intestinum Tenue) commences at the py- lorus, and terminates in the right iliac region by a lateral aperture into the large intestine. It is four-fifths of the length of the whole canal, and measures from twenty-four to twenty-eight feet.* When moderately distended its diameter is about one inch. It retains from one end to the other an uninterrupted cylindrical shape, with the exception that if the two ends be compared, the upper will be found larger than what is stated as the medium measurement, and the lower smaller; by which arrangement it will be found that the intestine decreases successively from above downwards, and, as a whole, is slightly conoidal or spindle shape, though this dimi- nution is so gradual that it is not perceptible in any short space. The small Intestine, like the stomach, consists of four distinct coats, the peritoneal, the muscular, the cellular, and mucous. The Peritoneal Coat is complete, and forms the external surface. It is continued afterwards in two laminae from the intestine to the lumbar vertebrae, thereby constituting the Mesentery. The two laminas, where they depart from the intestine, are loosely connected with each other, for the purpose of allowing room for the dilata- tion of the intestine, on the same principle which is exemplified in regard to the stomach. The Muscular Coat is next to the peritoneal. Its fibres are pale, and form a lamina not so thick as common writing paper. The * This is the generally received opinion of anatomists : it would appear, however, to be applicable only when the intestine is left attached to the mesentery; for if it be cut off and straightened, it will measure thirty.four feet, which, added to eight feet of large intestine treated in the same way, will amount in all to fortytwo feet. If to the estimate of this length we add what is lost by the doublings of the mucous coat, the entire length of surface must amount to nearly sixty feet, at least, in many subjects. 36 ORGANS OF DIGESTION. superficial ones are longitudinal, not very distinct, and too much separated to form a perfect coat: they are most abundant on the anterior semicircumference or the one most distant from the Mesen- tery. The others all run in a circular direction, approaching to the spiral, and are sufficiently numerous to form a perfect coat: none of them perform a complete circuit of the intestine, but are rather segments of circles. This coat is united to the peritoneal by a thin scattered cellular substance. The Cellular Coat of the small intestine, (Tunica propria) also called the Nervous, like that of the stomach, is only a lamina of dense cellular substance, which serves as a medium of connexion between the muscular and the mucous coat; and also conducts to the latter the blood vessels, nerves, and lacteals. When inflated and dried, it puts on a beautiful cotton-like appearance—just as the corresponding coat of other parts of the alimentary canal does under the same treatment. In the lion this membrane presents a most elegant clear tendi- nous appearance, and is so strong that it will bear, from the inte- rior, the pressure of a column of water eighteen feet high. The muscular and peritoneal coats splitting open, while it remains entire. Under this strong pressure of water neither the lacteals nor blood vessels are filled with it, which goes to prove that the intro- duction of articles into them, from the intestinal cavity, is a vital and not a physical action. The Mucous Coat is the most internal, and when it has been cleaned by maceration, exhibits an opaque pearly colour. It is remarkable for having its extent very considerably augmented beyond that of the other coats; by being thrown into a great num- ber of permanent folds, or duplicatures, which lie one upon ano- ther successively, like the shingles upon the roof of a house. These duplicatures are the Valvulae Conniventes, and are for the most part about three lines in breadth. They are either placed in the direc- tion of the circumference of the intestine, or are very slightly ob- lique ; generally they go all around, but many of them are segments of circles, and by being arranged successively, their ends pass one another, or are connected by slight elevations. They are more numerous and broad in the upper than in the lower half of the intestinum tenue, and are evidently intended to retard the progress downwards of alimentary matter, and to increase the surface for absorption and for exhalation. INTESTINAL CANAL. 37 The mucous membrane, on the side which it presents to the cavity of the intestine, is furnished with a great number of delicate cylindrical projections, resembling the down on the skin of an unripe peach, and called Villi,* from whence the term villous has also been applied to this coat. These villi are to be found in abundance every where; but in the upper half of the intestinum tenue they are so numerous as to stud its whole surface, and to be in contact with each other. They are from one fourth of, to a line in length; and some of them, when examined with a micro- scope, appear flattened and fungiform. According to the estimate of Meckel,f where they are thickest, every square inch of intestine furnishes about four thousand of them, and by extending this com- putation, with a proper allowance for diminished numbers below, their aggregatevamount is about one million.J Each Villus is composed of an artery, a vein, and a lacteal absorbent; all united by cellular substance. From the extreme vascularity of the mucous membrane, the blood vessels readily receive a fine injection and thereby become evident, forming a very delicate vascular net-work in each of the villi. It is gene- rally believed, that the absorbent opens on its surface, but whether by one or more orifices is yet unsettled. According to the cele- brated Lieberkuhn, there is commonly but one orifice at the end of each villus, and very rarely two: this assertion he considered him- self as having established by passing a current of air through the villus till it was dried, and then slitting it open. Hewson, Cruik- shank, and W. Hunter, on the contrary, are said to have found many more, amounting even to twenty, on such villi as were gorged with chyle. The subject has been fruitful in controversy to anatomists, and ranks many distinguished champions on each side; but from the minuteness of the parts under discussion, it is exposed to much fallacy and illusion; and is not as yet fully settled. The more important fact, however, is conceded by the admission of all, that there is a branch of the absorbent system in every * This is intended merely as an expression of the common and received notion, my own views are exhibited in the minute anatomy of this coat. Sect. hi. t Manuel D'Anat. t This is probably much below their real number; in an observation at the uni- versity we have found the villi on the ileum at its lower part amounting to six thou- sand four hundred to the square inch, but as their shape varies very much, as we shall see; a rule cannot be derived from their shape. 33 ORGANS OF DIGESTION. villus; and which has, for its function, the absorption of chyle from the cavity of the intestine. A more recent observation has been made by Professor Krause, and reported in Miiller's Archives for 1837. In the body of a young man who had been hung after taking a full meal, he found the villi of the jejunum beautifully filled with chyle. The lacteal of each villosity arose by several branches, of which some termi- nated by a free extremity, and others by anastomosis with each other. Judging from his plate, he does not appear to have traced any branch to the surface of the villus. Miiller says, that he him- self had never seen any opening at the extremity of the villi. This corresponds with my own experience, as I have, also, in one case had a fine opportunity of seeing them distended with chyle. The villi, however, under any circumstances, cannot be considered as the sole organs for the absorption of chyle, for in many animals they do not exist.* A more calm inquiry into this matter will, probably, bring us all to the conclusion, that the villi exercise a tactile more than an absorbing power, which office their strong analogy with the papillae of the cutis vera strongly points out. An abundance of Mucous Glands is found deposited in the cel- lular coat of the small intestine, between the muscular and the vil- lous ; their ducts open upon the internal surface of the latter, in the interstices of the villi, and from their smallness require the intes- tine to be floated in water, and examined with a magnifying glass, before they can be recognised. In order to see the glands them- selves, the intestine must be cleaned by soaking it in water; it is then to be slit open longitudinally, and held between the eye and the light, in which case the glands appear like little points or spots in the thickness of the intestine. They are more abundant in the beginning of the latter, decrease about its middle, and increase again towards its termination. Their structure is very simple, as they consist in a congeries of blood vessels, terminating in short canals secreting mucus f Some of these glands are microscopical, and are called cryptas; others are to be found from that size to a line in diameter, and flattened. They are either alone or in clusters. The former {Glandulce Solitaries, Brunneri,) are found principally about the » MQller, loc. cit., pp. 287, 288. t Soemmering, de Corp. Hum. Fabrica. INTESTINAL CANAL. 39 duodenum and the neighbouring portion of the small intestine, but also exist all the way down in a scattered manner. The latter {Glandules Agminata, Peyeri,) exist principally in the lower part of the small intestine, and are collected into clusters varying from a few lines to three or four inches in length, but seldom more than from eight to twelve lines broad. They are, for the most part, in elliptical patches, which, in a healthy state, may be recognised rather by a slight discoloration, than by the more ordinary means, and are generally situated some distance from the mesentery. There are about thirty of these clusters, of all sizes, in the ileum, and they are placed nearer and nearer to one another, in approach- ing the ileo-colic junction. All of these muciparous glands are too much flattened to project, sensibly into the cavity of the intestine, and, when they do, there is reason to believe that they are in a diseased state, at least in the adult. For the most part, in children. the glands of Brunner may be seen in the whole length of the small intestine. The mucous coat of the small intestine is every where extremely vascular. The Small Intestine, though an uninterrupted tube from one end to the other, is divided by anatomists into Duodenum, Jejunum, and Ileum. There is some reason for the first name, but the two latter may be very conveniently blended, as has been done by some, under the term Mesenteric Portion of the intestinal canal. The Duodenum, named from its being about twelve inches, or twelve fingers' breadth in length, is nearest to the stomach, and is the commencement of the canal. It is sensibly larger than either of the others, and is, moreover, susceptible of great dilatation, whence it has also been called Ventriculus Succenturiatus. Its direction is much varied: beginning at the pylorus, it first of all passes upwards and to the right side till it reaches the neck of the gall-bladder; it then turns downwards, so as to form a right angle with itself, and descends in front of the right kidney to the third lumbar vertebra, being there placed behind the superior lamina of the transverse mesocolon. It then forms a round elbow, crosses the spine obliquely, under the junction of the mesentery and meso- colon, in ascending from right to left; and making its appearance 40 ORGANS OF DIGESTION. to the left of the second lumbar vertebra, is there continued into the mesenteric portion of intestine. The beginning of the duodenum is moveable, and has a peritoneal coat continued from the lesser omentum; the descending and the transverse portions have no proper peritoneal coat, but are only loosely fixed between the laminae of the mesocolon; the termina- tion of the duodenum is both moveable and has a peritoneal cover- ing, from being at the commencement of the mesentery. From the course assigned to the duodenum, it is evident that it forms the segment of a circle, the concavity of which looks to the left side. This concavity is occupied by the head of the pancreas. The transverse portion crosses the spine below the pancreas, and is separated from it by the superior mesenteric artery and by the vena portarum: behind it are the crura of the diaphragm, the ascending cava, and the aorta. The organization of the duodenum is the same with that of other portions of the intestinum tenue. Its peculiarities consist only in a partial deficiency of peritoneal coat, and in its augmented size. Its internal or mucous coat is very much tinged with%bile, abounds in valvules conniventes, and about four inches from the pylorus is marked by a small tubercle or elevation, indicative of the orifice of the biliary and of the pancreatic duct. The Glands of Brunner are very conspicuous in this intestine, and are so nu- merous near the pyloric orifice, as to form with some a perfect layer, and to give it a granulated appearance for two inches or more. These glands are considered by Mr. Cruveilhier and Boehm to be pancreatic in their structure. The Jejunum and Ileum form the remaining length of the small intestine, and have no external marks of difference from each other. They are strung along the mesentery, and, in consequence of their great length, are thrown into folds or convolutions, which give to them a complicated appearance. There is, however, no difficulty in tracing them regularly from one end to the other. They occupy the umbilical, the hypogastric, and a part of the iliac regions, and are surrounded by the circuit of the colon. The upper two-fifths is the jejunum, and the lower three-fifths, the ileum* This distinction, originally introduced by Galen,* from a supposi- tion that the jejunum was more frequently found empty than any * Portal, Anat. Med. INTESTINAL CANAL. 41 other intestine, has no rigid anatomical support. The only diffe- rence between the two is, that the valvules conniventes, existing as they do in the whole length of the jejunum, become less abun- dant at the upper part of the ileum, and finally disappear entirely towards its lower extremity. They decrease indeed very sensibly at the lower part of the jejunum, and sometimes there are none at all in the ileum. In an observation made carefully on this matter by detaching the intestine from the mesentery—inverting it and then measuring, I found the valvules conniventes to cease as near as may be, in the middle of the length of the mesenteric por- tion of the intestinal canal. The above distinction into jejunum and ileum has been rejected by the most approved modern autho- rities, such as Haller, Soemmering, and Meckel. It sometimes happens, that the intestinum tenue has one or more blind pouches appended to its sides and opening into its cavity. The small intestine is supplied with blood from the superior mesenteric artery. Its nerves come from the sympathetic. The Mesentery {Mesenterium) is a process of peritoneum which serves, as mentioned, to connect the intestinum tenue to the poste- rior parietes of the abdomen, and extends its connexions from the left side of the second lumbar vertebra to the right iliac fossa. This attachment, called the root, is about six inches in length; whereas, its lower circumference, which encloses the small intes- tine by giving it a peritoneal coat, is, of course, the whole length of the bowel, (duodenum excepted,) and, consequently, from twen- ty-three to twenty-seven feet in length. This expansion becomes intelligible the moment that the arrangement of the part is in- spected, and is somewhat after the manner of a ruffle, except that it is not puckered at the root. The two laminae of peritoneum which form the mesentery, con- tain between them the superior mesenteric artery, and the corre- sponding portion of the superior mesenteric vein; an abundance of lymphatic or lacteal glands and vessels; ramifications from the solar plexus of the sympathetic nerves; and a considerable quan- tity of cellular and of adipose tissue. The superior lamina is con- tinued directly into the mesocolon, and at the place of junction the transverse part of the duodenum is very perceptible beneath. The lower lamina descends along the posterior parietes of the abdomen, concealing the large blood vessels there, and the ureters. Vol. II—5 42 ORGANS OF DIGESTION. Of the Large Intestine. The Large Intestine {Intestinum Crassum) receives the effete matter from the small, and is supposed also to make some peculiar secretion of fcecal matter from its internal surface. It exceeds much in its diameter the small intestine, and differs also from it in not being by any means so exactly cylindrical. It commences at the inferior end of the small intestine, and terminates at the anus, describing in this course, as mentioned, a circle which sur- rounds two-thirds of the abdomen, and embraces the intestinum tenue. Like the latter, though only a continuous tube, it is divided into three parts; the commencement of it, which is below the in- sertion of the ileum, and about two inches in length, is' the Ccecum, or Caput Coli; the remaining portion, which occupies almost its whole length, is called the Colon, until it reaches the pelvis, when the name is converted into Rectum. The Mesocolon is a reflection or duplication of peritoneum, that fixes the large intestine to the posterior parietes of the abdomen. This duplicature is not of a breadth so uniform as the mesentery, but allows to the middle of the large intestine very considerable motion, up and down, according to the distention of the stomach, while the lateral portions are very much confined. For instance, in the right iliac fossa the mesocolon is so short that the posterior surface of the gut is in contact with the iliac fascia, and adheres to it by loose cellular substance; and in the right and left lumbar regions the bowel is immoveably fixed in front of the kidneys near their outer margin : but in the space between these two points, that is to say, where the bowel traverses the hypochondriac and the epigastric or umbilical region, the peritoneal attachment, here called, from its situation, the transverse mesocolon, is so long and so loose that it forms a complete and moveable septum between the small intestine and the stomach. In the left iliac region, again, the large intestine, after having been bound down to the left lum- bar, is suddenly loosened by an increased breadth of the mesocolon, which permits it to form a large convolution, called its sigmoid flexure. The mesocolon is then continued into the pelvis in front of the sacrum, first of all a little to the left of the middle line of the latter, and, as it descends, it gets directly in front of the middle INTESTINAL CANAL. 43 line. The portion of it in the pelvis is called mesorectum, from the gut which it serves to attach. The composition of the mesocolon is precisely the same with that of the mesentery, though it be not so thick: it, therefore, con- sists in two laminae of peritoneum, which contain between them some adipose and cellular matter, along with the arteries, the veins, the nerves, and the absorbent vessels and glands belonging to the large intestine. When the large intestine is inflated, it is rendered very obvious that it decreases in size from its commencement to the lower part of the sigmoid flexure, it then increases again in size just above the anus. Its surface is arranged into three series or longitudinal rows of projections, separated by transverse depressions, the whole corresponding with an internal cellular arrangement, by the latter surface being the reverse of the former. Its coats, like the small intestine, are four in number; the peri- toneal, the muscular, the cellular, and the mucous. The Peritoneal Coat prevails in its whole extent, with the ex- ception of the lower part of the rectum : on the ascending and the descending portions of the colon, however, where the latter comes in contact with the parietes of the abdomen, the peritoneum does not invest it entirely; but the transverse portion or the arch, as it is called, and the sigmoid flexure, are completely surrounded. The surface of this intestine is studded with small projections of various lengths, called Appendices Epiploicas, which are small duplicatures of the peritoneal coat containing fat. The Muscular Coat is thin, and like that of the small intestine, consists of two orders of fibres, the longitudinal, and the transverse or circular. The longitudinal fibres have the peculiarity of being collected into three equidistant, flattened fasciculi or bands, of about half an inch in breadth, which begin by a common point at the extremity of the coecum, and extend to the upper end of the rectum. One of them is along the line of junction with the mesocolon, another anterior, and the third inferior. These fibres, being shorter than he other coats of the gut, have the effect of puckering them into the internal cellular condition alluded to; for, when they are cut 44 ORGANS OF DIGESTION. through, the intestine is much elongated, and its cells disappear. It occasionally happens that the longitudinal fibres, instead of being confined to the bands mentioned, exist in considerable quan- tity over the intermediate spaces; in this case the cellular arrange- ment is not so complete, and in some instances is entirely dispensed with; of the latter, an example is in the Anatomical Museum. The circular muscular fibres form a thin semi-transparent lamina beneath the last, and do not present any peculiarity of interest, they make a thicker layer than exists in the small intestine. The Cellular Coat, or Tunica Propria, is a thin lamina of dense cellular substance, serving to connect the muscular with the mu- cous coat, and to conduct the blood vessels and nerves to their terminations on the latter. The Mucous Coat lines smoothly the internal face of the cellu- lar, and has no doublings or folds, exclusively in it, like the valvulae conniventes of the small intestine.* The transverse projections which it makes between the longitudinal bands, into the cavity of the gut, and'which separate the cells of the large intestine from each other, are not mere duplicatures of it alone, but are also con- stituted by the other coats. Near its commencement this coat has the fungous appearance of the stomach, but about the sigmoid flexure it has a plain, smooth, and, to a degree, a polished surface. It has but few villi, such as exist in the small intestine; indeed, some anatomists deny that it has any, and I have not myself seen them after repeated and care- ful examinations. Its muciparous glands and follicles are nume- rous, and the former, when somewhat enlarged, project; they are very conspicuous about the sigmoid flexure, and in the rectum. Its lacteals are not abundant. The mucous coat of the large intestine is very vascular, but not so much so as that of the small intestine. Each division of the large intestine has some peculiarities of structure and connexions; which may now be attended to. The Coecum, or Caput Coli, is generally from an inch and a half to two inches long, has a rounded termination below and * This may be considered as the general rule: if the gut be examined, however, in its whole length, here and there narrow folds may be found in some subjects. INTESTINAL CANAL. 45 somewhat to the left, from which proceeds an intestinal process, the Appendicula Vermiformis. The latter is from three to four inches long, is cylindrical, has a diameter of two or three lines, and consists of the same number of coats, having the same struc- ture with other portions of the intestinal canal; its base is the place from which the tjiree longitudinal bands start. It is attached to a narrow duplicature of peritoneum, a process of the mesentery, which permits it to float loosely in the abdomen. It seldom con- tains faeces, but is kept distended by flatus. The ccecum, as mentioned, is, for the most part, confined to the right iliac fossa, but we very frequently see it with a length of peritoneal attachment permitting it to descend for a short distance into the lesser pelvis. The Ileo-colie Valve {Valvula Bauhini) is formed at the junc- tion of the ileum with the caput coli. This valve, destined to prevent the return of faecal matter from the large into the small intestine, consists in a transverse elliptical opening, or slit, whose two lips become approximated in the distentions of the colon. The ileum runs into the left wall of the large intestine, and continues its cellular and mucous coats into the corresponding coats of the latter. The circular muscular fibres of the large intestine separate to a certain degree to permit this introduction, but their farther separation is restrained at each commissure or corner of the lips,, by a blending of the structure, aided by a few ligamentous fibres, designated as the retinacula of Bauhin or of Morgagni; which, however, are frequently not very distinct. This separation is also restrained by the two longitudinal bands between which the lips are placed, one of which bands is at the posterior commissure, and the other only a short distance from the anterior. The lips themselves, formed principally by the mucous membrane, approach one another after the manner of the ship dock or canal gate; the superior is somewhat broader than the inferior. Their power, as well as their existence, depends entirely on the tension which is kept up by the natural connexions of the parts; for a very slight dissection causes them to become almost effaced, and instead of forming an elliptical transverse'opening, to be converted into a round patulous one. The Colon, properly speaking, has some regional distinctions 5* 46 ORGANS OF DIGESTION. which are serviceable to accurate description. The right lumbar colon, which is bordered in front by the small intestine, and behind, by the right kidney, extends from the ileo-colic valve, to the mar- gin of the false ribs of the corresponding side. The transverse colon, bordered above by the stomach, and below by the small in- testine, goes from one hypochondriac region to the other. It is generally found more distended than the other portions. The left lumbar colon descends from the hypochondriac region of the left side to the sigmoid flexure, being bordered behind and to its right margin by the left kidney, and in front by the small intestine. The sigmoid flexure, placed in the left iliac fossa, forms a convolution, but is very indifferently described by the term applied to it. It is occasionally very long and loose, and terminates at the left sacro- iliac symphysis. It is not unfrequently found destitute of the par- titions which prevail in other parts. The Rectum begins at the left sacro-iliac symphysis, and passes obliquely downwards to the centre of the sacrum, thence in front of the middle line of the sacrum, and of the coccyx, to terminate at the point of the latter. It is not regularly cylindrical, but, just above the anus, is dilated into a wide pouch, flattened from before backwards by the pressure of the bladder, and very distinguishable upon the introduction of the finger, for it is but seldom in a con- tracted state. It, of course, has a flexure by adopting itself to the concavity of the sacrum, and is bounded in front by the bladder, the prostate gland and the vesiculae seminales of the male; and by the vagina and the uterus of the female. The peritoneum covers only the superior two-thirds of the rec- tum, and attaches it by the short duplicature, called the meso- rectum, to the front of the sacrum. A small pouch, passing down between the vesiculae seminales almost to the base of the prostate, is formed, as mentioned previously, by the peritoneum in its course from the rectum to the bladder. The muscular coat of the rectum has a thickness and redness surpassing much that of any other intestine, and is divided verv clearly into two laminae, the external of which consists in longitu- dinal and the internal in circular fibres. The external forms in itself a complete coat continuous with the longitudinal bands of the colon, but is much increased in thickness'over them by additional fibres. The circular fibres also form a complete coat, and, just INTESTINAL CANAL. 47 below the pouch of the rectum, are multiplied so much for eight or ten lines as to be a perfect internal sphincter muscle, bearing a strong analogy with the pyloric muscle of the stomach.* At the anus, an arrangement of the muscular coat prevails, which, is not sufficiently attended to by anatomists. The longitudinal fibres, having got to the lower margin of the internal sphincter, turn under this margin between it and the external sphincter, and then ascend upwards for an inch or two in contact with the mucous coat, or rather its cellular substratum, into which they are finally inserted by fasciculi which form the base of the columns of the rectum ; many of the fibres, however, terminate also between the fasciculi of the circular fibres. This connexion must have obviously much influ- ence in the protrusions of the mucous coat, which take place in hemorrhoids and in prolapsus ani. The mucous coat of the rectum is thick, red, and fungous, and abounds in mucous lacunae and glands. It is smoothly laid above, but below it is thrown into superficial longitudinal folds called columns. At the lower ends of the wrinkles,, between the columns, are small pouches of from two to four lines in depth, the orifices of which point upwards; they are occasionally the seat of disease, and produce, when enlarged, a painful itching. An original ob- servation of Dr. Physick, on the nature of this affection, and the remedy for which consists in slitting them open or removing them, induced me to look for the ordinary natural structure, which I have found to be as now described.! The radiated wrinkling of the anus is from the influence of the external sphincter ani muscle. In some subjects, large cells are formed in the cavity of the rec- tum by transverse doublings of the mucous coat only, resembling * It lias been recently asserted that there is also a sphincter muscle four inches above the anus, half an inch wide in front, and one inch wide behind, from whence according to Mr. Velpeau the fibres go in crossing one another to fix themselves to the front of the sacrum. Mr. Lisfranc appears to have first announced it and Mr. Nekton to have described it. Malgaigne, Anat. Chirurg. vol. 2d, p. 343. Paris, 1838. I doubt very much the uniformity of the distinct existence of such a mus- cle, not having been able to find it in the dissections which I have instituted for the purpose, unless a portion of the ordinary circular fibres should have been selected for that designation, in which case several others may be said also to exist. t See an interesting paper on Fistula in ano, by M. Ribes, in Mem. de la Society D'Emulation, vol. 9, 1826; where the influence of this structure is alluded to.—It appears that Glisson and Ruysch first described them as valves. Also, an elaborate and excellent article by Dr. Reynell Coates, in the Cyclopaedia of Pract. Med. and Surgery, Philada. l83Sr, under the term anus. 48 ORGANS OF DIGESTION. the valvulas conniventes of the small intestine; this, however, is not the most frequent arrangement, though deserving of notice. It takes place under the following mechanism. About a finger's length from the anus there is a puckering of the gut, or deep wrinkling, such as occurs in the colon, and it arises from a similar cause, that is, an abbreviation of the longitu- dinal layer of fibres of the gut: this abbreviation is not wholly cir- cular, but occupies the semi-circumference of the gut on one side, and then a little higher up, the semi-circumference of the other side. This shortening of the gut brings the fasciculi of its circular muscular fibres more together, and, therefore, accumulates them into a greater thickness. At a corresponding part on each side of the gut in its interior, exists a transverse doubling of the mucous coat forming the valvula connivens alluded to. The result of this arrangement is a semi-circular valve on each side, one above the other, the margins, or diameters of which pass each other in the empty and contracted state of the rectum, but touching at the same time, and they present an additional barrier to the involun- tary evacuation of faeces.* Most subjects, however, have the mucous coat without these valves, and merely in superficial wrinkles of various directions. The large intestine is supplied with blood from a part of the superior mesenteric artery, from the whole of the inferior mesen- teric, and from the internal pudic. Its veins empty into the vena portarum. Its nerves are derived from the solar and the hypo- gastric plexus of the sympathetic. SECT. III.—ON THE MINUTE ANATOMY OF THE MUCOUS COAT OF THE ALIMENTARY CANAL. In the preceding account of the mucous coat of the stomach and bowels, I have admitted the most generally received opinions, * It has latterly been advanced by Mr. O'Beirne, that in a natural state the rec- tum is empty, and that the accumulation of fxces preparatory to a stool occurs in the sigmoid flexure of the colon, where they are retained by a contraction of the upper end of the rectum. The principal ground of this opinion is, that fcecal matter is rarely met with in the rectum. The observation is so contradictory to my expe- rience in the dissecting room and on patients, that I cannot but reject it, though it appears to be obtaining some currency, or at least is quoted respectfully. Journal Hebd. 1833, vol. xiii. p. 126. Malgaigne, Anat. Chir. vol. 2d, 341. ANATOMY OF THE MUCOUS COAT. 49 as it is in every way proper for medical men to be aware of them. Having been, however, much occupied, a few years ago, in ascer- taining the pathology of Asiatic cholera* by dissections, the obser- vations which I then made upon the healthy and diseased structure, have induced me to modify very much my former views, as will be seen in the following pages. The mucous coat of the alimentary canal, in a healthy state, and successfully injected, appears to consist almost entirely of a cribriform intertexture of veins. These veins being commonly empty at death present themselves then as a soft spongy structure, which gives rise to the ordinary description of its sensible condi- tion as a velvety layer. The most minute injection of the arteries scarcely makes itself visible among these veins, when they are pro- perly injected also; a straggling branch only here and there exhi- biting itself. The arborescence of the arteries is confined to a level beneath the venous intertexture, and is there developed to an extreme degree of minuteness, being intermixed with correspond- ing venous ramuscles, generally larger and more numerous than the arteries themselves. This arrangement seems to occur in that surface of the cellular coat, which makes the base or ground of the mucous. The fine venous trunks of this deeper layer have their originating extremities directed vertically towards the cavity of the gut, and by that means receive the blood of the first venous intertexture or layer, as the petrous sinuses join the cavernous, or the veins of the penis arise from its spongy structure. The meshes of the first venous intertexture are exceedingly minute, and vary in a characteristic manner in the stomach, small intestine and large. This intertexture is very different in its looks from a com- mon vascular anastomosis, and produces in the colon an appear- ance resembling a plate of metal pierced with round holes closely bordering upon each other; these holes constitute, in fact, the fol- licles of Lieberkuhn, so called from their discoverer ;f these folli- cles are gaping orifices, the edges of which are rounded off, and their depth is that of the thickness of the venous anastomosis ; being bounded below by the arterio-venous layer, just alluded to, and by the cellular coat of the part. Nothing short of an entirely success- ful injection will exhibit this venous anastomosis as described; and it may be seen either by injecting a vein, or an artery provided * Amer. Journ. Med. Sciences, Vol. xvi. May, 1835. t De fabrica et actione Villor. intest. ten. Leid., 1745. 50 ORGANS OF DIGESTION. the injection passes from the arteries, into the veins, but the latter process is the least desirable, because we lose the benefit of a dis- tinction of colour between the two sets of vessels.* Ordinary modes of examination give no evidence of the existence in the alimentary canal, from the cardiac orifice of the stomach to near the anus, of an epidermis or epithelium; on the contrary, they rather lead to a belief of its being absent, in consequence of the softness, tenuity, and transparency of the mucous membrane; but that it is really present, may be proved by the following process:— Tear off the peritoneal coat from a piece of small intestine—invert the part and inflate it to an emphysematous condition; the epithe- lium will then be raised as a very thin pellicle, and may be dried in that state; but as this pellicle retains the air, we hence infer that it lines the follicles, and is uninterrupted by any perforations. This epithelium, if the part be previously injected perfectly, shows dots of injecting matter like those left in the rete mucosum upon a mi- nute injection of the skin, but no arborescence if it be raised up from the veins by the inflation stated. In so doing the villi disap- pear, are in fact unfolded. In addition to the above proof, the microscope in the hands of numerous modern observers now shows, according to the original opinion of Lieberkuhn, the existence of an epithelium over the whole alimentary canal, and which is formed of minute soft scales. The villi cannot be seen to any advantage except they be erected by an injection, in which case those of the upper part of the small intestine are found to run into each other very much like the con- volutions of the cerebrum, and to press upon each other's sides in the same way. Some of them, however, are merely semi-oval plates, the transverse diameter of which exceeds the length or ele- vation. At the lower end of the small intestine they become sim- ply conical projections, somewhat curved, with the edges bent in or concave, and they retain this mechanism until they entirely dis- appear near the ileo-colic valve. In the whole length of intestine * The observations more recently of Dr. Gaddi of Modena, have resulted in wit- nessing a similar indisposition of the arteries to ramify in the mucous coat, and the almost exclusive prevalence of the venous vessels there. He has some views besides of a peculiar nature, such as that the extremities of the veins begin by open mouths on the cav.ty of the intestine, then unite to form a hollow sphere situated in the submucous tissue, and that the terminating ends of the arteries discharge into these spheres or vesicles. Brit. & For. Med. Rev. Oct., 1841, p. 530 ANATOMY OF THE MUCOUS COAT. 51 there is, however, every variety of shape of villi, from oblong curved and serpentine ridges, to the laterally flattened cone standing on its base; the first condition changing gradually to the last in the de- scent of the bowel. Conformably to this definition of villi, none exist either in the stomach or colon, for there we have only the venous mesh. The villi of the jejunum are about the thirtieth of an inch high, and those of the ileum about one-sixtieth. In the ileum, the superficial venous layer has great regularity and the conical villi stand out beautifully from its anastomoses, or in equivalent language, from the divisions of the follicles. In the upper part of the small intestine the follicles are in equal number to what they are in the ileum; the regularity of their arrangements being interrupted by the long serpentine and oval villi; but inva- riably the same venous intertexture exists and forms, in both parts, the chief bulk of the villi, by passing into them. In the stomach the follicles vary much in size, and there is an arrangement whereby many of the smaller ones are seen to open into the larger: on an average about two hundred and twenty-five are found upon every square of one eighth of an inch, which would give of course to an inch square sixty-four times that amount, or fourteen thousand four hundred follicles. Conceding the whole stomach to present an area of ninety inches, which is probably below the mark when this organ is moderately distended, as exhi- bited in the preparation upon which this calculation is founded, the entire number of follicles is one million two hundred and nine- ty-six thousand. The great uniformity of size of these follicles in the colon, and its even surface, enable us to count them with more certainty, and they appear to exist at the beginning of this gut at the rate of about four hundred for every eighth of an inch square, but in the sigmoid flexure at the rate of about two hundred to the same area; they become, in fact, both smaller and less numerous in descend- ing towards the anus. Their average may be stated, therefore, as three hundred for every one-eighth of an inch square—and as nine- teen thousand two hundred for every inch square. Admitting the entire area of the colon to be five hundred inches, and nineteen thousand two hundred of these follicles, to exist on every inch square, the aggregate number will be nine millions six hundred and twenty thousand. In the colon the resemblance is almost exact with what is called 52 ORGANS OF DIGESTION. the perforated card or Bristol board, used by ladies for working embroidery or variegated needle-work. Again, estimating the whole area of the mucous coat of the small intestine at fourteen hundred and forty inches, and allowing for interruptions occasioned by villi; about three hundred and ninety follicles exist upon every one-eighth of an inch square, or 24,960 upon an inch: say then, that about twenty-five thousand follicles are found upon every square inch, and the two numbers multiplied, produce thirty-six millions. The entire number of follicles in the whole alimentary canal, is, by the preceding estimates, forty-six millions nine hundred thou- sand, and upwards. I am very far from pretending to have counted them all, but have made an approximation to the actual number by observing sections of different portions of the same sub- ject, and verifying the observations upon other subjects. The external surface of the cutis vera presents, as it were, in outline, the same follicular arrangement; the venous reticular inter- texture appearing broader, not quite so perfect, and more shallow, and forming the papillae; but as additional experiments are want- ing, it may be passed over with this transient notice; perhaps, indeed, a more skilful hand in adopting the hint may perfect the details.* In the stomach, the largest of these follicles is about one-ninety- eighth of an inch in diameter, and the smallest about one-four hun- dred and ninetieth. In the colon the largest is about one-two hun- dred and forty-fifth of an inch in diameter, and the smallest about one-four hundred and ninetieth. In the small intestines their size varies in about the same ratio as in the colon, but they are much more irregular in shape, being scattered more in groups, in conse- quence of the villi intervening: some of them penetrate obliquely towards the foundations of the villi; hence, when examined from the exterior, their distribution is more regular, and they are seen lodged in the cellular coat of the gut. I have endeavoured to keep the estimate of the number of folli- cles below what other calculators would make it upon an observa- tion of my preparations, and a fair measurement of the area of the alimentary canal, lest the number may seem excessive and incre- * It is probably this which constitutes the bloody pimples (bourgeons sanguins) of the skin. ANATOMY OF THE MUCOUS COAT. 53 dible; I have, therefore, the most reasonable assurance of being within bounds on that point. I may now ask their use; is it to secrete or absorb? If they are simply secernents of mucus, the number, one would think, much greater than so limited a secretion requires—moreover, why is it that they become smaller and less numerous towards the lower end of the large intestine, where greater lubrication is required for hardened faeces; in addition,are not the glands of Brunner, {solitaries,) and of Peyer, {agminatcs,) amply sufficient to furnish the required mucus ? Again, after most sedulous observations upon the villi of all kinds, finely erected by my injections, and placed under most accurate, simple, and com- pound microscopes, I find, invariably, a polished reflecting surface, uninterrupted by foramina, either at their ends or sides, while many of these follicles are found passing obliquely into their bases. An excellent Woollaston's doublet, which makes the villi of the ileum appear an inch long, exhibits them with a polished translu- cent surface, without foramina, except where a villus from acci- dent has been broken, a contingency readily recognised by one in the habit of viewing them. Finally, if the lacteal foramina of Lieberkuhn and others, do really exist, why is it that the raising of the intestinal epidermis, by inflation, does not exhibit these fora- mina by the air escaping through them, but, on the contrary, admits of a dried preparation in that state, the villi being com- pletely effaced.* Taking into consideration these several objections to the theory of the follicles being secreting orifices, it appears to me that a bet- ter idea of their use is called for, which suggestion is submitted to the profession, with the hope that a more capable person will re- move the difficulty, by additional confirmation of preceding theo- ries, or by the invention of a new one: for my own part, I am much inclined to adopt the opinion of their absorbing faculties. It is generally conceded that the erection and prehension of the Fallopian tube is produced by a vascular turgescence, in which the veins, from their number, must execute an important part; in like manner, as these intestinal follicles are formed in the midst of * In these and other microscopical observations, I owe much to my young friend, now Demonstrator of Anatomy, Dr. Paul Beck Goddard, who has acquired an ac- curacy and skill in such matters deserving of much confidence. Vol. II.—6 54 ORGANS OF DIGESTION. veins, their orifices only become erect and patulous by the disten- tion of those veins, and cannot be well seen by the eye alone, espe- cially in the small intestine, unless an injection has succeeded fully; but the erection of these veins during digestion puts the follicles in a similar condition; there is, therefore, some ground of inference, that the act of the Fallopian tube in conveying a germ, and of a follicle in conveying into the thickness of an intestine congenial matter, may be analogous. The follicles would seem at least not to be essential to the secre- tion of mucus, as it is found where the follicles do not exist, for example, in the frontal, maxillary and sphenoidal sinus, and also in the cavity of the tympanum. Notwithstanding the facility with which we can detect these follicles, I have failed entirely under various means of examination, in finding any orifices to Peyer's glands, in the dried intestine: they appear to be merely small lenticular excavations* in its sub- stance, and wherever a cluster of them exists, it disturbs the ar- rangement of the villi, and gives to them a scattering unequal dis- tribution. I would also suggest very respectfully to anatomists whether our knowledge in regard to them is sufficiently exact to render farther inquiry useless ? for my own part it appears that this subject requires some additional attention. The above view, relative to the structure of mucous membrane, presents at least a degree of novelty, by determining, with some precision, the whole number of the Gastro-enteric Follicles of the human body, or Follicles of Lieberkuhn, and how they are in every instance formed by meshes of veins, while the arteries enter only inconsiderably into the composition of the same mucous membrane, to an amount in some measure comparable to the presence of the arteries in other erectile tissues, as the corpus spongiosum and cavernosum penis. In the latter it is familiar to every practised anatomist, that, the branches of the arteries are but small, as they terminate in the cells of the penis, which are to be considered as only a modification of the incipient stage of venous trunks. If the corpus spongiosum were in fact spread out into a thin and single * This observation has been confirmed in Germany by Boehm, who has come to the same conclusion. He says that they contain a white milky and rather thick fluid, with numerous round corpuscles of various sizes, but mostly smaller than blood globules. Am. Journ. Med. Sc. vol. xxi. p. 218. ANATOMY OF THE MUCOUS COAT. 55 membrane, so as to line a hollow viscus, it would present no very undue representation of what I have denominated the superficial venous layer of the alimentary canal; it being also admitted that within the circuit of every anastomosis, a follicle was formed. Viewed on the preparations of the mucous membrane of the small and large intestines which I have, these follicles appear like puncta lachrymalia disseminated by thousands over every inch square, and existing so invariably upon every part, that, as I have stated, the smallest calculation of their numbers puts them at from forty to fifty millions. It may now be represented, that it is the whole of this vascular and follicular structure, endowed with vital actions the most im- portant to life, and presenting in the aggregate an area of about thirteen square feet, the size of a small breakfast table; whose mor- bid derangements constitute the essential features of Asiatic cholera. It has been shown in some of my dissections, that this apparatus in the progress of cholera is detached entirely from the stomach and colon, in consequence of the excessive actions going on in them. The small intestines also, in some of my preparations, exhibit in patches a similar phenomenon; but as the entire obser- vation has been presented to me in its true light only since the disappearance of the disease, I have had no means of ascertaining the extent to which they suffer in this way. The anatomy of the muciparous system of the alimentary canal unquestionably requires a more exact attention than has been here- tofore bestowed upon it, especially so as to distinguish between that part which is really glandular, and the foramina or follicles now under consideration. The following extract will explain the difficulty which still exists in regard to a proper conception of the latter. " The mucous glands, called also follicles or cryptae mucosae, are to the membranes of that name what the sebaceous follicles are to the skin; that is to say, folds of the mucous membrane in form of a cul-de-sac, whose orifices open upon that membrane. These follicles have not yet been discovered over the whole surface of the mucous membrane; but here, as with the skin, analogy leads us to admit them. It is not long since they have been discovered in the pituitary membrane, where their existence had been denied. Be this as it may, we shall use the same observation upon these 56 ORGANS OF DIGESTION. glands that was made on the sebaceous, viz. the impossibility of making an exact dissection of the capillary tissues does not allow us to discover all the forms of animal matter; but wherever a particular humour is found in a tissue, we are forced to cpnclude that this latter is organized in such a manner as to be able to pro- duce it, and when in place of one humour we meet with many, we must acknowledge that the tissue is complex. Such is precisely the case with the mucous membrane of the digestive canal, and especially.of the stomach, which could have a form of animal matter calculated to furnish digestive juices, although no gland destined to that purpose is discoverable."* This desideratum of positive evidence, instead of the inductive, is clearly supplied by my preparations. In infancy, especially, the mucous glands have a sensible thick- ness, which enables us to see them, but the smallest of them require the aid of a microscope, and appear to have been described by C4aleati.f As the paper is not to be had in any of the public libra- ries of this city, I can only quote from it on the current authority of anatomical works. In a note to the anatomy of the human body by Sir Charles Bell, article Intestine, it is stated as follows:— " It has been supposed that the fluids excreted from the surface of the intestines were furnished by very minute foramina, (which are visible by particular preparations,) in the interstices of the villi. See the letter of Malpighi to the Royal Society of London on the pores of the stomach, and the paper by M. Galeati in the Bologna Transactions, on the inner coat, which he calls }he cribriform coat. The pores, according to Galeati, are .visible through the whole tract of the canal, and particularly in the great intestines." Meckel designates these as glandular bodies under the name of glandular mucosa, cryptcs minimcs. Another order of glands are those of Brunner.J They are readily found in the duodenum at all ages; and particularly well in infancy, as low down as the ileo-colic valve. The third order are the glands of Peyer, dis- * Broussais' Physiology. First American edition, p. 419. t De cornea ventriculi et intestinorum tunica. Comm. Bonon., 1745. t Glandute intestini duodeni vel pancreas secundarius; discovered in 1715. See Mangetus, Theat. Anat. where this paper is introduced with the plates illustrative of it. ANATOMY OF THE MUCOUS COAT. 57 covered in 1677.* The celebrated Ruysch appears also to have understood the existence of the follicles of the stomach, and Swammerdam to have had some idea of those of the small intes- tines,f and he calls them tubuli glandulosi intestinorum interiores. I may here remark, that the figure of the villi of the small intes- tines given by Hedwig, in his Disquisit. Ampullarum, &c. 1797, and which appears, from its introduction into Caldani's and M. Jul. Cloquet's Anatomy, to have a classical value, is, judging from my own preparations, too much a work of the imagination, executed under probably some fallacious views of the part itself: a cluster of cylindrical villi, with holes at the ends, would be an anomaly, for those of the upper part of the intestines are either serpentine folds, as represented in my preparations, with branches running into contiguous folds; or semi-oval laminae; while those lower down are of a flattened conical shape, somewhat bent, but in even- instance they are destitute of what has been termed by Lieberkuhn an ampulla, and to my eye have uniformly polished surfaces, un- interrupted by foramina. Mascagni has also introduced views of a good kind in regard to the follicular structure of the stomach and colon.J But it is to Sir Everard Home, that we are indebted for one of the best papers on the glandular structure of the stomach of different animals.§ As the real muciparous glands have an orifice leading into each by the admission of anatomists, the follicles described commonly by them, are of this description, and are not comparable in number to the follicles found in the venous meshes. The highest estimate of the number of the former, as made by M. Lelut, fixes them at about forty-two thousand.|| In consulting many of the distinguished modern authorities on this subject, there seems to be scarcely anv thing in the anatomy of the intestinal canal which is presented in a more indefinite way; especially in regard to the small intestines, than the difference between the follicles, properly speaking, and the glands; and none of them, so far as 1 know, have undertaken to approximate the entire number of the follicles and to point out how each one is the centre of a venous anastomosis, is formed by * See also Mangetus for the description from Peyer, with his plates. t Mangetus Theat. Anat. Vol. I. p. 310. J Prodromo della grande anatomia. Tab<. xiii. § Phil. Trans. 18C7 and 1817; and also his Comparative Anatomy. |] Bouiliaud, Traite du Cholera, p. 256. 6* 58 ORGANS OF DIGESTION. it, and always exhibits itself in a collapsed state when the vein is not turgid.* SECT. IV.—OF THE GENERAL ANATOMY OF THE MUCOUS MEMBRANES. The extent of the mucous coat of the alimentary canal, and the important and varied sympathies which it has with most other parts of the body, render useful some remarks on membranes of this kind generally. Mucous Membranes are so called from the nature of the secretion which they furnish: and the term having been first applied to the lining coat of the nose, a similitude of character has caused its extension to that of other organs. The celebrated Bichat, the founder of the science of general anatomy, was the first to adopt fully, and to perceive the value of this classi- fication ; since which it has been almost universally received by anatomists. As the skin forms an external covering to the body, so mucous membrane lines the internal surface of the hollow viscera. When it is recollected that this membrane forms an internal tegument to the whole alimentary canal, from the mouth to the anus; to all the urinary and genital apparatus; to the whole respiratory sys- tem, from the nose down the trachea and throughout the luno-s; it will be admitted that its extension exceeds much that of the skin. A mucous membrane presents two surfaces, one of which ad- heres to the contiguous parts, and the other is free by being inter- nal. The adherent surface is attached by a cellular structure somewhat condensed. This cellular structure is principally re- markable for its want of disposition to secrete fat into its inter- stices ; a property of immense importance, as without it, obstruc- * The anatomy of the Gastro-intestinal mucous membrane has elicited several good papers in Europe since 1835, inclusive, the period of my own publication They are rather confirmatory of preceding observations than distinguished by novel. ties, and the venous anastomosis does not seem to be understood or appreciated except by Dr. Gaddi, of Modena, alluded to in a preceding note. In addition to the authorities already quoted the reader may advantageously consult Boehm de Gland, Intest. Struct. Penit. Berol, 1835. Boyd on the Structure of the Mucous Mem- brane of the Stomach. Edinburgh, 1836. Likewise Recherches Anatomiques sur la Membrane Muqucuse, &c, par M. Natalis Guillot in L'Experience, p 161 Paris, 1837-8. GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 59 tions would be continually occurring to the destruction of life: it is pervaded by a multitude of fine vessels and nerves, running for- ward to be spent upon the mucous membrane; and has been unfor- tunately named nervous coat, by anatomists of high authority. The strength of attachment which it furnishes is somewhat varied; for example, in the small intestinal canal I have often seen the mucous membrane caught at one end and entirely withdrawn from the muscular coat, an experiment which alone can give rigid ideas of its greater length, as by it all the duplicatures or valvulae conniventes are stretched out. The experiment succeeds much more certainly by the regular pressure of a column of water be- tween the tunics of the intestine. The mucous membrane of most organs is arranged into wrinkles and duplicatures, for the purpose of augmenting its extent. This arrangement prevails in the nose, and, as mentioned, in the oesophagus, in the stomach and intes- tines; to say nothing of many other instances which are noticed in the description of each organ. In some examples, they are per- manent, and, in others, depend on the state of contraction of an exterior muscular coat. The interior face of the mucous mem- branes, allowance being made for the inequalities just stated, more- over, presents, when closly viewed, an abundance of more minute depressions and of elevations, causing it to resemble velvet. Some of these depressions are so large as to give it a cellular appear- ance,* as in many parts of the intestinal canal, and in the gall-blad- der, and have been particularly described by Sir Everard Home. In regard to organization, the mucous membranes are of a soft, spongy consistence; easily yield to mechanical violence; and de- pend for their strength upon the surrounding cellular coat.. They are not of a uniform thickness; for example, they are much thinner in the urinary and genital apparatus, than in the alimentary canal; they also present some varieties of consistence. They yield very readily to putrefaction, and are quickly reduced to a pulpy state by the action of the mineral acids. Caustics of all kinds act more promptly on them than on the skin, owing to the protection of the latter by a dry epidermis; Bichat states, that in the practice of the Hotel Dieu, this effect is frequently exemplified, by the administra- * They are not to be confounded with the follicles, but are a miniature represen. tation of what is called tripe, in culinary language. 60 ORGANS OF DIGESTION. tion of lunar caustic among the common people for the purpose of poisoning. The nitric acid leaving the silver, quickly applies itself to the mucous membrane of the stomach, and disorganizing it, forms a whitish eschar, which, if life be preserved long enough, is finally detached in a membranous form. One of the remarkable properties of the mucous surfaces of the stomach and intestines is, that of coagulating milk. According to the experiments of Spallanzani, the gastric juice, in the living state, assists in this change; but it is perfectly well known in do- mestic affairs, that the dried stomach of a calf, where the juices have been completely evaporated, is also productive of it. The observations of the same author led him to conclude, that the peri- toneal and the muscular tunies of the stomach are insufficient to produce this effect. The internal surface of the mucous membranes is furnished with small projecting points or spiculae, called papillas or villi. They are particularly conspicuous and numerous, as mentioned, on the upper surface of the tongue and in the small intestine, and bear an analogy of function and organization with the very fine papillas which are seen invariably on the surface of the cutis vera. These papillae are constantly furnished with nervous filaments, giving them a high degree of sensibility; and with an abundance of blood vessels. The term papillae has been more exclusively applied to the projections on the surface of the tongue, from their greater size; they are there also more distinctly covered with an epidermis, frequently called epithelium, or periglottis. The villi, from their connexion with the process of digestion, have been emphatically denominated the roots of animals. According to M. Beclard,* who has examined them upon a plan of his own contrivance well suited to accurate microscopic observations, they are presented under a diversity of shapes. Those of the pylorie half of the sto- mach, and of the duodenum being broader than they are Ion*?, are composed of very small thin laminae, having a tufted arrangement. Those of the jejunum are long and narrow, having more the form commonly assigned to them, while in the lower part of the ileum and in the colon they again become laminated. It should be observed that notwithstanding the assertion of * Anat. Gen. p. 253. These notions are not, however, in unison with my own, as just stated. Sect. III. GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 61 Lewenhoeck, Hewson, Hunter, and others, the fact is still called in question, by many of the most distinguished anatomists of the present time, MM. Beclard, J. F. Meckel, Rudolphi, Miiller, &c, whether the orifices of the lacteals are, under any circumstances, visible on the surface of the villi. Admitting that they do not open as stated, the power of interstitial absorption in the mucous membrane will still account for the chyle finally getting into the lacteals, as well as for fluids passing into the circulation from the stomach, when its continuity with the intestinal canal has been interrupted.* The Epidermis or Epithelium of mucous membranes is very distinct at their external orifices, but becomes less and less appa- rent towards the interior of the body, until it finally cannot be dis- tinguished by the eye alone; and anatomists of a former period generally considered that it is entirely deficient, notwithstanding the assertion of Haller to the contrary. It is a matter of common ob- servation, that when the interior of mucous membranes is exposed by an eversion for a long time, to the action of the atmosphere; they take on more of the structure of skin, and become evidently covered with a cuticle which protects them and diminishes their secretion. This is exemplified in eversion of the vagina from pro- lapsed uterus, in elongated and tumid labia interna, and in other ways: restore the parts to their natural situation, and they are brought back to their original structure. In the partial prolapse of the mucous membrane of the rectum, from piles, corresponding circumstances occur. From this we infer, that the full deve- lopment of cuticle depends very much upon the degree of exposure which any surface of the body has to undergo. The reverse also takes place : shut up or close any surface of the skin so that it is put in the condition of an interior cavity, and it immediately begins to assimilate itself to a mucous membrane. This is proved by the tendency in young children to a detachment of the cuticle, or ex- coriation of the opposed surfaces of the deep wrinkles about their thighs and in their perineum; a tendency obviated by the practice of nurses of covering these surfaces with powdered starch. It is also manifested frequently in the dressing of wounds with sticking * Should the suggestion of the absorbing powers of the gastrc-enteric follicles which I have proposed in Section third, be correct, it will dispose of the difficulties and opposing opinions alluded to in this paragraph. 62 ORGANS OF DIGESTION. plaster, where an incautious approximation of the contiguous sur- faces of the skin, not only is followed by excoriation, but even by ulceration; a fact, the importance of which was formerly set in proper relief by Dr. Physick in his surgical lectures, and of which I have seen an example in a case of extirpated female mamma. The state of this question is, in fine, such that I think we may safely admit upon general observation the existence of a very thin epidermis on the alimentary canal, but so pulpy that it cannot be distinguished except by the process alluded to in Section third of this Chapter. There is less difficulty in proving the existence of an epithelium every where else on mucous membranes, but the fact of its universal presence may be considered now, so definitely settled by the recent microscopical observers, as scarcely to admit of discussion. The mucous membranes vary in colour from a very light pink to a deep red, which is owing to the blood that circulates in them. In cases of suffocation, they become almost brown from the con- gestion of blood in them, while in fainting they turn white from the desertion of the latter. The vessels after having penetrated the thickness of the membrane, ramify with extreme minuteness on, jts surface. The veins in an injection invariably predominate bver the arteries by their greater size and distensibility. In con- sequence of their superficial situation, the vessels being unsupported on one side, are exposed to rupture from slight concussions; in this way hemorrhage is produced in the lungs from coughing, and bleeding at the nose from blows upon the head. Exhalent orifices exist in great numbers in the mucous mem- branes: this is especially the case in the lungs, where the pulmo- nary perspiration, as it is called, is very obvious to common observation. Elsewhere, this discharge is so much blended with the mucus of the part, that it is difficult to appreciate its quantity. From the superficial situation of the blood vessels, it is clear that the exhalent orifices or pores, have but a short course to run. This is considered by Bichat as a satisfactory reason for the ten- dency of the blood to escape through them, or to ooze out where there is no rupture. Absorbents exist also in great numbers, as proved by the absorp- tion of chyle, of watery drinks from the intestinal canal, and by the inhalation of the vapour of spirits of turpentine into the lungs, GENERAL ANATOMY OF THE MUCOUS MAMBRANES. 63 rapidly communicating the particular smell of this article to the urine. There are, moreover, cases recorded of obstructed urethra, where the urine has been almost entirely absorbed by the mucous coat of the bladder. In regard to nerves, the mucous membranes are well furnished with them. Bichat has remarked that wherever these membranes are situated near the surface of the body and enjoy common sen- sibility, they are almost wholly furnished from the central portions of the nervous system, as the brain and spinal marrow: this is ex- emplified in the conjunctiva, the pituitary membrane, the palate, the glans penis, &c. On the contrary, the sympathetic nerve fur- nishes the intestines, the bladder, and the excretory tubes gene- rally. Mucous Glands, as they are called, exist throughout the system of mucous membranes, being situated either under them or in their thicknesses. From them is derived the mucilaginous fluid which lubricates so abundantly their interior surfaces, so as to facilitate the passage of extraneous bodies, and, at the same time, to protect the membrane from mechanical violence. These glands are of various sizes, from that of the tonsils and the muciparous glands on the lips, cheeks, and root of the tongue, to the almost impercep- tible cryptae of the bladder and urethra. Their shape is either lenticular, rounded, or that of a pouch. The former two have their parietes of a sensible thickness, but the last are too thin to be distinguished from the mucous membrane itself. For the most part, the excretory duct of these glands is short and patulous, so as to lead directly into the substance of the gland. This is re- markably the case with the tonsils, which consist in a congeries of these follicles; and with the glands on the root of the tongue. In some animals they are so numerous as to form almost a distinct lamina to the intestines; after the manner of the human subject, on the palate and parietes of the mouth. The Mucosity discharged from these glands is one of the prin- ciples of animals, and, as is well known, exists also to a great extent in some vegetables. When perfectly pure and fluid, it is white, transparent, inodorous, and insipid. It is insoluble in alco- hol, but soluble in acids. Water forms more than nine-tenths of it, the remainder is mucus, properly speaking, blended with some neutral salts of soda and potash. 64 ORGANS OF DIGESTION. The mucus which covers the surface of the mucous membranes consists chiefly of separated particles of epithelium mixed with a fluid exudation, while the mucous follicles are said to pour out a fluid holding mucous globules suspended. The mucous membranes are exposed to a multitude of morbid alterations, such as polypus, scirrhus, cancer, phlegmorrhagiae or serous fluxes, blennorrhagias or mucous fluxes, inflammation in all its forms, gangrene, ulcerations, and congestions. CHAPTER V. Of the Assistant Chylopoetic Viscera. SECT I.—OF THE LIVER. The Liver {Hepar, Jecur) secretes the Bile, and is the largest glandular body in the human frame. It, as mentioned, occupies the whole of the right hypochondriac region, the upper half of the epigastric, and, as it becomes thinner in going towards the left side, it occupies a small space in the right superior part of the left hypochondriac region. Its whole superior face is in contact with the diaphragm; on the left it is bounded by the spleen, and below by the stomach and the transverse colon; behind it, are the verte- bral column and the ascending cava. The shape of the liver is like one half of an ovoidal .body cut into two in the direction of its long diameter, and having the thick end turned to the right side. It is about ten inches in length by six or seven wide, and weighs from four to five pounds in the adult. Its colour is a reddish brown, generally; though, on its under surface and about its edges, broad blue or black patches are constantly met with, which do not indicate any morbid derange- ment. Its upper surface is of a uniform convexity, rather more promi- nent at the right posterior part than elsewhere; adjusts itself accu- rately into the concavity made by the under surface of the dia- THE LIVER. 65 phragm; and is unequally divided from before backwards by the suspensory ligament. The anterior margin is thin, and is notched where the suspensory ligament begins; the posterior margin is much thicker, and has near its middle a broad depression, to fit it to the pro- jection of the vertebral column. The ascending vena cava forms a superficial sulcus upon this margin, and frequently there is a com- plete canal through the substance of the liver for transmitting it. The right extremity is very thick, and almost fills the hypochon- driac region of that side, while the left extremity is reduced to a thin, tapering, and flexible edge. The under surface of the liver is much more irregular than the upper; it is traversed in an antero-posterior direction, in a line corresponding with the attachment above of the suspensory liga- ment, by the umbilical fissure, {Sulcus Umbilicalis) which extends from the notch in the front edge to the depression behind, and ob- tains its name from having accommodated in the foetal state, the umbilical vein, now converted into a round ligamentous cord. In the posterior part of this fissure is likewise to be seen, in the same condition, what remains of the ductus venosus. The anterior por- tion of the umbilical fissure is not unfrequently converted into a complete canal, by a portion of hepatic substance crossing it like a small bridge. The transverse fissure {Sulcus Transversus, Inter- medin) is situated in the middle of the under surface of the liver, and extends along a third or fourth of the long diameter of the latter. It begins somewhat to the left of the umbilical fissure, and crossing it at right angles, proceeds towards the right extremity. It contains the vena portarum, the hepatic artery, and the hepatic duct, lymphatics and nerves ; all of which are bound to each other by a close cellular substance. The suspensory ligament above, and the umbilical fissure below, give occasion to divide the liver into Lobes, Right and Left; of which the right is by much the largest, and accommodates almost entirely the transverse fissure, having also on its under surface some subordinate elevations, to wit, the Lobulus Spigelii and the Lobulus Quartus, together with the Gall-Bladder. The Lobulus Spigelii is placed between the transverse fissure and the posterior margin of the liver, to the right of the posterior end of the umbilical fissure. Its shape is somewhat prismatic, bifurcating in front; one of the elongations or prongs is a papilla overhanging the transverse fissure, and is, therefore, considered as Vol. II.—7 GG ORGANS OF DIGESTION. one side of the gate-way {porta) opened for the vena portarum; the other elongation is a small ridge, sometimes called Lobulus Caudatus, and is lost gradually on the under surface of the great lobe, by inclining to the right. The' Lobulus Quartus, or Anonymus, is not by any means so elevated as the last, but having a flattened surface, is placed in front of the transverse fissure, between the fore end of the umbilical fissure and the gall-bladder; its posterior extremity is the other side of the gate-way {porta) of the Liver, and is just opposite to that furnished by the Lobulus Spigelii. The liver, from being completely enveloped in peritoneum, has a smooth glossy appearance. The reflections of this membrane, from it to the parietes of the abdomen, form the ligaments, as they are called, which consist each of two laminae. The Falciform Ligament, or Suspensory, containing in its anterior margin the remains of the umbilical vein, now called Ligamentum Teres, begins at the umbilicus, extends from it along the linea alba and the middle line of the diaphragm, and, as mentioned, is reflected to the upper surface of the liver, from the anterior to the posterior margin. The Right Lateral Ligament is situated behind, and de- parts from the back part of the diaphragm to the posterior margin of the right lobe. The Left Lateral Ligament also goes from the back part of the diaphragm, and is attached along the posterior margin of the left lobe. Where the suspensory ligament inclines on each side into the lateral, it passes with so much obliquity as to leave some portion of the posterior margin of the liver unco- vered by peritoneum; the latter, where it describes the periphery of this space, has been rather unnecessarily designated as the Coronary Ligament. In addition to the peritoneal coat, the liver has another, con- necting it with the peritoneum, and seeming to be only condensed cellular substance, which also penetrates into the substance of the gland, and holds its constituent parts together. It is particularly well seen within the circle of the coronary ligament. Of the Organization of the Liver. The glandular substance of the Liver is fragile and easily lace- rated ; and consists of a congeries of spherical or polyhedrical THE LIVER. 67 grains, called by Malpighi acini from their resemblance to small berries; they are best seen on tearing the organ, are united in mass by the elongations of the cellular coat, and traversed by the trunks of the blood vessels. Each of these granulations is about the size of a millet seed, and is a representative of the entire gland, as its structure is complete in itself; being formed by the terminations of the blood vessels, and by the origin of a branch of the hepatic duct, called the porus biliarius. When examined with a micro- scope, it is said that these acini are observed to be composed of a yellow and of a brown-looking substance; it has not, however, occurred to me to see the distinction in a very satisfactory way, though it is recognised by anatomists of high authority.* The liver is made extremely vascular by the ramifications of three kinds of blood vessels, the Vena Portarum, the Hepatic Artery, and the Hepatic Veins. The first two convey the blood to it, and the third removes it again, into the general circulation, by emptying into the ascending vena cava. There are also the commencing radicles of the hepatic duct, lymphatic vessels, and the nerves. The Vena Portarum having arisen from the junction of all the veins of the stomach, intestines, pancreas and spleen, is about three inches in length when it reaches the transverse fissure, by going over the duodenum and under the pancreas. It immediately divides into two branches, called collectively the Sinus Venae Por- tarum, which is at right angles with the trunk of the vein; the right branch being the shortest and largest, is distributed by radia- ting trunks to the right lobe of the liver; the left branch is distri- buted, after the same manner, to the left lobe, to the lobulus spigelii, and to the lobulus quartus. Some of its branches anastomose with the hepatic veins, which accounts for the ease with which an injection will pass from one to the other. Other branches of a smaller description anastomose with the biliary ducts, but with less freedom than in the preceding case; and lastly, the most deli- cate ramifications are spent upon the cortical or yellow matter of the acini, without penetrating to the brown.f . The Hepatic Artery is a branch of the cceliac, and in approach- ing the transverse fissure divides into three or more branches, that penetrate the substance of the liver, between the sinus venae por- » Bichat, Meckel, &c. f Mappe3, J. F. Meckel, loc. cit. 68 ORGANS OF DIGESTION. tarum and the ducts as they come out; one branch goes to the right lobe, another to the left, and a third to the lobulus spigelii. There is some variety in regard to the precise mode of distribution, and their division into subordinate ramifications frequently occurs before they get fairly into the substance of the liver. When there, they seem to be intended for the nourishment of this organ, accord- ing to the observations of several able anatomists; and follow the ramifications of the vena portarum and of the biliary ducts, form- ing upon them a very delicate and complicated tissue of anasto- mosing vessels; some of which, probably the vasa vasorum, com- municate with the vena portarum. The Hepatic Veins arise in the acini from the capillary termi- nations of the vena portarum and the hepatic artery. Their branches are successively accumulated into three large trunks, the collective area of which vastly exceeds that of the vessels bringing the blood to the liver. Two of these trunks come from the right lobe and one from the left, to empty into the ascending cava, while it is still in contact with the liver, immediately below the diaphragm; just below the preceding trunks there are five or six, sometimes more, small hepatic veins, coming from the posterior margin of the liver, and from the lobulus spigelii. The hepatic veins are destitute of valves, and remarkable for the thinness of their pa- rietes. An injection passes readily from them into the other systems of vessels. They may be recognised by their insulated course, and by their consisting in trunks which converge from the periphery of the liver to the vena cava, while all the other vessels diverge from the transverse fissure to the periphery, and conse- quently cross the course of the hepatic veins. The commencing radicles or ramifications of the Hepatic Duct, take their origin in the acini; and, as is said, upon the boundary between the two kinds of matter, avoiding the brown and passing through the cortical.* The larger branches converge into their respective trunks successively or in pairs; while the primordial, or most minute ones, converge several of them to the same point, giving a penicillous appearance. These several tubes constitute the Biliary Pores (Pori Biliarii) and are always in the same group with the branches of the Vena Portarum and Hepatic Artery. It is unsettled whether these brush-like or penicillous ends of the pori * J. F. Meckel, loc. cit. THE LIVER. 69 biliarii are enlarged at their free extremities so as to be there like a pin at its head in a manner so common in glandular structure. Krause asserts the fact, and states that the enlargement measures from ^ to ~T of an English line, and there are said to be prepara- tions of the kind in Utrecht.* It is asserted that a fine injection passes more readily from them into the lymphatics than into any other order of vessels; which may account for the promptitude of jaundice upon an obstruction of the hepatic duct. The most minute branches of the biliary ducts in the acini are so close together that they seem to be united to one another. Their dia- meter, according to Miiller, varies from 7iy to 7£o of an English inch; they are, therefore, much larger than the finest capillary blood vessels. According to the observations of Mr. Kiernan,f the acini of anatomists generally should be called lobules, inasmuch as they consist in a collection of smaller granulated bodies, to which he restricts the name of acini. The objection to this principally is, that it introduces a new definition on a point heretofore considered as settled in the universal phraseology of anatomists, but as his descriptions are founded upon this assumption, the latter may be admitted for the time. His statement then is that the finer branches of the vena portarum, which he calls Interlobular veins, form a perfect and minute plexus surrounding the lobules or small granu- lar masses of the liver; they then form convergent lines of vessels directed towards the centre of each lobule and communicating by transverse branches with one another. These latter connexions or the sets of veins making them constitute the lobular venous plexus, and in their intervals are placed what he calls the acini or subordinate granules. In pursuing farther his line of description, we have next to say that the Hepatic Duct forms a plexus upon the lobules like that of the vena portarum; the plexuses of the contiguous lobules being indisposed to anastomose, though he thinks there is ground to be- lieve in such anastomosis. The interlobular biliary ducts then pene- trate the lobule and ramify by anastomotic connexion through it. The Hepatic Artery makes also a plexus upon the surface of * Mailer, Phys., p. 491. London, 1840. t Anat. and Physiol, of Liver, Phil. Trans. London, 1833. 7* 70 ORGANS OF DIGESTION. the lobule, and penetrates interiorly from its periphery towards the centre. Its ultimate branches supply the meshes of the vena por- tarum ; of the venae hepaticae, and of the biliary ducts, but their final termination is unsettled; Kiernan believes that it is in the vena portarum ; and Meckel that they end in the incipient branches of the venae hepaticae. The Hepatic veins, according to Mr. Kiernan, are seen as a small trunk in the centre of a lobule; this trunk arises from the convergence of from four to eight venules from the periphery to the centre of the lobule. The trunks having escaped each from its respective lobule then unite with contiguous trunks similarly circumstanced, and as the arrangement is progressive by the suc- cessive junction of larger and larger trunks, we have, finally, the large Hepatic veins formed which discharge into the ascending vena cava. It is stated by Mr. Kiernan, that the elements of the above arrangement of ducts and blood vessels are formed very distinctly in the left lateral ligament of the liver. He appears not to have succeeded in injecting the hepatic veins from the hepatic artery, though he can inject them from the vena portarum. His injection was probably not fine enough, as there is not the slightest difficulty in filling all of the ducts and blood ves- sels of the liver from either set, provided one throws in a very fluid injection. The use of water simply will prove this beyond doubt; and I have made a very complete injection of the lymphatics of the liver when I threw the common size injection coloured with vermilion, into the hepatic artery. Miiller considers that there is an ultimate plexus of capillary blood vessels with which the other three communicate freely, this is probably the fact, including the lymphatic system also, but the precise mode of its formation is as yet not ascertained, an idea long ago advanced by Chaussier in regard to all glandular struc- tures. As an ultimate feature in the microscopical structure of the liver its parenchyma or peculiar final atomic arrangement, according to Wagner, consists in nucleated cells, now ascertained to be a very common feature in the textures generally of the human body. At the bottom of the transverse fissure of the liver is to be found a dense cellular fibrous tissue, which invests the vena portarum, THE LIVER. 71 the hepatic artery, and the biliary ducts; and, as they all keep together in their ramifications, this tissue follows them throughout the substance of the liver, and thereby forms sheaths for them. It may be considered as continuous with the processes sent in from the cellular coat; and, contrary to the opinion of Glisson, whose capsule it has been called, it is devoid of muscular structure. The liver appears in the embryo to be originally formed by a protrusion of the walls of a part of the intestinal canal;* the lungs and pancreas present a similar mode of evolution. Of the Gall-Bladder. The Gall-Bladder {Cistis Fellea) is a reservoir, for the bile secreted by the liver. It is fixed on the under surface of the great lobe, to the right of the umbilical fissure, and removed from the latter by the lobulus quartus.J It is an oblong pyriform sac, having its anterior extremity or fundus projecting somewhat beyond the anterior margin of the liver, while the posterior end reaches to the transverse fissure. Its long diameter inclines slightly to the right side, so that it is not precisely in an antero-posterior line. It varies in its shape in different subjects, being much more sphe- roidal in some than in others. Its fundus is rounded and obtuse, while the posterior end is gradually reduced to a narrow neck, which is bent up on itself, so as to retard the flow of a fluid through it. Its upper surface is in contact with the substance of the liver, and is received into a broad shallow fossa, while the lower sur- face is projecting, and by coming in contact with the transverse colon, tinges it with bile, by transudation after death. The Gall-Bladder has three coats, a peritoneal, a cellular, and a mucous one. The Peritoneal Coat is not complete, but only covers that part of the sac not received into the fossa on the under surface of the liver; it is, therefore, a continuation of the peritoneal coat of the latter; sometimes, however, the gall-bladder is so loosely attached * Muller, loc. cit., p. 490. t I have seen an instance where it was to the left of the umbilical fissure, on the small lobe. The latter was much longer than common. Dec. 1830. 72 ORGANS OF DIGESTION. to the liver that it almost hangs off from it, in which case the peri- toneal coat is nearly complete. The Second coat is condensed cellular membrane, (Tunica Pro- pria.) Through it ramifies a great number of lymphatics, and blood vessels; below,it attaches the peritoneal to the mucous coat, and above, the latter to the liver. The Mucous Coat is always tinged of a deep green or yellow, by the bile which it contains percolating after death; for it is said to be, before that, of a light colour. This coat is thrown into irregular tortuous folds or wrinkles of extreme delicacy, in the intervals of which are many round or polyhedrous cells, causing it to look, when floated in water, like a fine honey comb: such as are about the fundus of the sac are superficial, and not so distinct; but those near its middle and about the neck, are a line or a line and a half deep. In the neck or apex, and in the beginning of the cystic duct, are from three to seven, sometimes twelve, semilunar duplicatures of the interna] membrane, which also retard the flux and afflux of any fluid, though they do not afford so much resis- tance to the ingress as to the egress of it. These duplicatures are sometimes partially arranged into a spiral valve, projecting from the inside of the duct, and forming two or three turns.* Very small mucous follicles exist over the internal face of this membrane, the discharge of which fills the gall-bladder when the secretion of bile has been interrupted by diseased action, as in yellow fever, or by scirrhus of the liver. The artery of the gall-bladder is a branch of the hepatic. Its veins empty into the vena portarum. Its nerves come from the sympathetic, and its lymphatics join those of the liver. The gall-bladder is developed as a diverticulum from the Hepatic Duct. Of the Biliary Ducts. A succession of very fine branches having arisen from the acini of the liver, these branches are united into three or four trunks by the time they reach the transverse fissure. The trunks then co- * Discovered latterly by M. Amussat, of Paris. M. Amussat has also detected muscular fibres in the gall-bladder and biliary ducts, in which we see an analogy with other hollow viscera.—Am. Jour. Med. Sciences, Vol. ii. p. 193. THE LIVER. 73 alesce into a single Duct, the Hepatic, of eighteen or twenty lines in length, and about the diameter of a writing-quill. The Hepatic Duct is then joined at a very acute angle with the duct from the gall-bladder, which is somewhat shorter and smaller; the union of the two forms the Common Duct, {Ductus Communis Choledochus.) The latter is larger than either of the others singly, and is three or three and a half inches long; it descends behind the right ex- tremity of the pancreas through its substance, passes nearly an inch, obliquely, between the coats of the duodenum, becoming at the same time diminished in diameter; and, finally, ends by an orifice still more contracted, on the internal face of this gut, on its second turn, and about three or four inches from the stomach. The ori- fice is marked by a small surrounding tubercle somewhat obscured by the valvules conniventes. The Hepatic, the Cystic, and the Common Duct are situated, as mentioned, along the right margin of the lesser omentum, and have the vena portarum and the hepatic artery to their left. The bile ducts are formed by two coats; the external is a fibrous, lamellated, and very extensible membrane, while the internal is mucous, having the same structure with that of the gall-bladder, of which it is in direct continuation. In the Cystic Duct, and at the lower part of the Common Duct are several longitudinal folds. The Common Duct sometimes receives, just before it empties into the duodenum, the Pancreatic Duct. Of the Bile. This secretion from the livfer, is of a deep yellow, sometimes green colour: when recent, it is thin and fluid; but after it has been conveyed to the gall-bladder, and permitted to remain there for some time, it becomes as thick as molasses, and increases also in the intensity of its colour and in bitterness. Some anatomists have believed that there was a more direct communication between the liver and the gall-bladder than that through the hepatic and the cystic duct; but repeated and close observations have proved the opinion to be erroneous, or at least destitute of proper proof: it is therefore, clear, that the difference between the hepatic and the cystic bile, depends upon the watery particles being removed from 74 ORGANS OF DIGESTION. the latter by the absorbing power of the internal coat of the gall- bladder. According to Berzelius, the chemical analysis of bile furnishes about eighty parts of water, eight of a particular substance which assumes a resinous condition on the application of an acid: three of mucus; and nine of saline matters; of which soda is a principal constituent. SECT. II.—OF THE SPLEEN. The Spleen {Lien, Splen) is situated deeply in the posterior part of the left hypochondriac region, and is bounded above by the diaphragm, below by the colon, and on the right by the great end of the stomach, and by the pancreas. It is not ascertained that it secretes any thing. Its colour varies from a deep blue to a dark brown. In shape it resembles the longitudinal section of an oval, being flat or very slightly concave on the surface next to the stomach, and convex on that contiguous to the diaphragm. Occasionally its margins are notched, but this is not invariably the case. Its flat surface is slightly depressed longitudinally in the centre into an imper- fect fissure, where the blood vessels enter it by six or eight foramina. Several spleens sometimes exist in the same individual, in which case the supernumerary ones are not larger than nutmegs. The common size of this organ is about four and a half inches long, by two and a half or three wide, in which case it has a solid firm feel; but it very often exceeds these dimensions; its transition and va- rieties of magnitude are so frequent, that no settled rule can be established. In its inordinate enlargements I have seen it only a little smaller than the liver; its texture in this case is soft and easily lacerated. It is fixed in its place by three lines of reflection or processes of peritoneum, called ligaments, whose names indicate their places of attachment. They are the Gastro-Splenic Ligament or Omen- tum, which passes from the stomach to the spleen, and in which are the vasa brevia of the stomach; the Splenico-Phrenic Liga- ment, which goes from the spleen to the diaphragm: and the Splenico-Colic Ligament, which passes from the spleen to the THE SPLEEN. 75 colon. These reflections, by being continued over the spleen, give it a complete peritoneal coat, which is raised up with more diffi- culty than the corresponding membrane of any other viscus of the abdomen, and is commonly thrown into very small inequalities or wrinkles. The internal or proper coat of the spleen is a grayish, compact, extensible, and elastic membrane, the use of which is evidently to sustain the natural shape of the organ, and to support its parenchy- matous structure. It sends in processes to accompany the blood vessels, and from its internal face there proceeds a multitude of lamellae and of fibres, which traverse its cavity in every direction, and reduce it into a cellular condition, not unlike the spongy struc- ture of bones. The spleen, in proportion to its size, is furnished to a remarkable degree with blood. The largest branch of the coeliac artery runs to it along the superior margin of the pancreas, forming numerous serpentine flexures, and distinguished' for its thickness ; it divides into several trunks for penetrating into the spleen, and enters by the foramina in the fissure. The veins come out by a number of trunks equal to what the artery is divided into; they assemble then into a single trunk, which attends the artery along the pancreas, and is remarkable for the tenuity and extensibility of its coats. The splenic vein is destitute of valves, and empties into the vena portarum. The spleen has also lymphatic vessels; and is furnished with nerves from the solar plexus. Of the Intimate Structure of the Spleen.—The Splenic artery having penetrated into this organ, is divided and subdivided into a radiating succession of very fine branches, which, according to the injections of Ruysch, do not anastomose with each other; in con- sequence of which, one part is sometimes finely injected and not another, of which, in my own observations, I have had an example. The veins, on the contrary, do anastomose, not only as regards the collateral branches of the same primitive trunk, but also by the collateral branches of different trunks. These anastomoses are not large. The arteries terminate freely in the veins, as may be proved by fine injections, and by the microscope. The mass of the spleen, upon superficial examination, seems to consist in a dark brown bloody pulp, which is contained in the cells 76 ORGANS OF DIGESTION. dividing the cavity of the internal coat, and may be easily demon- strated by tearing the spleen, and scraping it with a knife handle. MM. Assolont and Meckel believe, that blood, besides being in the arteries and veins, is placed in a state of particular combina- tion and of intimate union with the other organic elements of this viscus, and with a large quantity of albumen; and that this combi- nation of the blood forms the dark brown pulp alluded to. The great quantity of albumen in the pulp, is readily proved by the hard coagulum which it forms, wben steeped in alcohol. A question has arisen whether the pulp be extravasated in the cells which contain it, or whether it be still retained in the extre- mities of the blood vessels. Superficial examination is in favour of the first, but M. Marjolin denies it on the following grounds; that injections, cautiously made, pass immediately from the arte- ries into the veins; and that the spleen, when successfully in- jected and frozen, does not exhibit ice in the interstices of its ves- sels, while their capillary ramifications distended by the injected fluid, are distinctly seen. From these facts he concludes that the glandular structure of the spleen is formed essentially of arterial and venous capillary vessels with very delicate and extensible coats; that they communicate with one another without the intermedium of any cell; and that the extreme tenuity of these vessels, and their extensibility in every direction, are sufficient to explain the aug- mentation of volume of the spleen, under certain circumstances, as well as the promptitude of its diminution under others. The pulpy substance of the spleen under the microscope, is com- posed of small spheroid or oval granules of a reddish brown colour, and about the size of the globules of the blood. According to Mr. Gulliver,* they are more unequal in size than the blood discs, their diameter varying from 1-1777 to 1.600 of an inch, and they are found in blood taken from the splenic vein. They are easily sepa- rated from one another. The minute arteries of the spleen ramify in tufts among them and then terminate in a plexus of venous canals whose walls are so thin that the veins appear as mere channels in the pulp. In addition to this pulp, many observers have met in the spleen with an abundance of rounded corpuscles, varying in size from an almost imperceptible magnitude to a line or more in diameter.f * Gerber's Genl. Anat. p. 102. t Malpighi, Ruysch, Hewson, Home, Dupuytren, Meckel, &c. THE SPLEEN. 77 They are of a gelatinous consistence, soft, grayish, and semi-trans- parent, and either cluster together, or are widely separated. By Malpighi, they were considered glandular, and by Ruysch,* as con- voluted vessels. Professor Soemmering, from the following para- graph, seems to join in the opinion of the latter: "Qui nonnun- quam occurrunt, acini vel glomeruli, microscopii ope accuratissime explorati nihil sunt, nisi vasorum fasciculi, vel teretes penicilli aut cirri vasculosi." According to the observations of Sir Eve- rard Home, they swell considerably after an animal has finished drinking. The corpuscles are seen with difficulty in the human spleen. in animals they are much more distinct, as in the hog, sheep, and ox. Miillerf admits their connexion with the arteries, but is in- clined to consider them as excrescences from their coats, as in his injections the arteries were seen to pass through, but not to ramify in them. Their exact structure is undetermined. The spleen, from having no excretory duct, and consequently, from our inability to ascertain whether it secretes, has its nature and uses shrouded in mystery. No single theory concerning it has ever been generally adopted, for speculations have multiplied in proportion to the obscurity of the subject. The idea, however, on the use of this body, which to me is most reasonable, is, that it acts a subsidiary part to the liver. It would seem, indeed, as a general rule in regard to glandular structures and such other highly vascular organs of the body as have an intermittent func- tion, that the blood which is sent to them during their state of activity, should be passed off through a different channel, while they are in a state of repose. This does a double service, it pre- vents superfluous secretions, and it also keeps up the vascular equi- librium of the body, as there must be always in readiness a quan- tity of blood sufficient for the supply of any secretion which mav be wanted for the time. This proposition will derive some additional illustrations from the foetal state. The kidneys being then inactive the capsular renales take off their blood, and thereby prevent what would other- wise be a very inconvenient secretion of urine; again, the lungs being also then inactive, the circulation through them is propor- * Epis. Anat. IV. t Physiol, p. 618. Vol. II.—8 78 ORGANS OF DIGESTION. tionately reduced, and the superabundant blood is conducted through the thymus gland. But as the full functions of the lungs and of the kidneys are established upon birth, and continue unin- terrupted during life, their supplementary organs, the thymus gland, and the capsulae renales, are not wanted, and they wither away after the early period of infantile existence is passed. In regard to the liver, its functions also suspended during the foetal state, are of an intermittent kind throughout life, the spleen may, therefore, be considered a vicarious organ for it during the whole period of existence, receiving its blood during the conti- nuation of uterine life, and, in the intermission of action, during common life. The spleen is, therefore, an organ useful to the foetal and to the perfect state, and we, consequently, never see it in the collapsed and dwindled condition of the thymus gland, and renal capsules. The same reasoning which applies to the spleen, will also apply to the Thyroid Gland: the latter may be considered as exe- cuting for the salivary glands during foetal and perfect exist- ence, what the spleen does for the liver. For it is ascertained, that the salivary glands are inactive during foetal existence, have only an intermittent action during perfect life, and, therefore, probably stand in need of a supplementary organ during their pe- riods of inactivity. SECT. III.—OF THE PANCREAS. The Pancreas {Pancreas) secretes saliva, and is the largest of the salivary glands. It is fixed in the lower back part of the epi- gastric region; and extends horizontally across the spine, being separated from it by the lesser muscle of the diaphragm. It is connected to the spleen on the left; at its right extremity is sur- rounded by the curvature of the duodenum; is bounded in front by the stomach, which conceals it; and is placed between two laminae of the mesocolon. The pancreas is about six or seven inches long, two wide, and flattened before and behind. Its figure would be represented by a parallelogram, were it not that its right extremity is en- larged considerably into a head or tuber, to which Winslow gave THE PANCREAS. 79 the name of the Lesser Pancreas. The anterior face of this organ is turned obliquely upwards, and is covered by the superior lamina of the mesocolon. The posterior face looks obliquely downwards, and is in contact with the aorta, the vena cava ascendens, the superior mesenteric vessels, and several nerves: along the superior margin of this face exists a long superficial fossa, occupied by the splenic artery and vein. With the exception of the loose covering given by the meso- colon, the pancreas has no peritoneal coat; neither has it an ap- propriate tunic, unless we consider as such the lamina of con- densed cellular membrane which envelops it, and sends in processes between its lobules, as in the case of the salivary glands in the neck. Of the Minute Structure of the Pancreas.—This body, like the other glands, which discharge saliva, is of a light gray or pink colour. It consists in lobules of various forms and sizes, united by an intermediate cellular tissue, and having their interstices occupied by numerous blood vessels. These lobules, by a slight maceration, may be separated and resolved into small granular masses, constituting integral portions of the gland. The arteries of the pancreas come principally from the splenic, as it cruises along the superior margin. The veins empty into the splenic, and thus, finally, into the vena portarum. It is furnished with nerves from the solar plexus, and has lymphatics. The excretory duct of this gland {Ductus Wirsungii) arises, by very fine roots or tubes, from each of the small granular masses. These roots have vesicular commencements like those of the sali- vary glands. The tubes coalesce into larger ones, which run transversely from the periphery towards the centre of the gland, inclining slightly, at the same time, towards the right. These secondary tubes finally discharge successively into a single one, which runs the whole length of the gland nearly in its middle. The single tube, by these additions, enlarges continually from left to right, being small where it begins at the splenic extremity of the pancreas, and about the size of a crow-quill at the duodenal. At the latter place, it is joined by the duct of the lesser pancreas, which is derived after the same rule as itself. The pancreatic 80 ORGANS OF DIGESTION. duct, almost immediately afterwards, empties into the ductus com- munis choledochus; or runs at the side of the latter, and makes a distinct opening near it into the duodenum, at the posterior part of the second curvature. The diameter of the cell-like extremities of the duct of the Pan- creas is from six to twelve times greater than that of the capillary blood vessels. BOOK V. OF THE URINARY ORGANS. The Urinary Organs, {Organa Uropoietica) being destined to secrete and convey the urine out of the body, consist in the Renal Capsules, the Kidneys, the Ureters, the Bladder and the Urethra. Of the Kidneys. The Kidneys {Renes) are two glandular bodies for the secre- tion of urine, fixed one on either side of the spine. They are in the back part of the lumbar regions, have their internal edges inclining very slightly forwards, and extend from the upper mar- gin of the eleventh dorsal to the lower margin of the second lumbar vertebra : the right, however, is ten or twelve lines lower than the left, owing to the thick posterior margin of the right lobe of the liver, which presses it downwards. The kidneys are covered in front by the peritoneum and the lumbar portions of the large intes- tine, but in such a manner as to be separated from them, in cor- pulent subjects, by a surrounding layer of fat; behind, they repose upon the lower part of the great muscle of the diaphragm, upon the quadrati lumborum, and upon the upper end of the psoas magni muscles. The kidney is a hard solid body, of a brown colour; in shape it is a compressed ovoid, excavated on the margin which it pre- sents to the spine, and bears a very strong resemblance to the common kidney bean. Its flat surfaces present forwards and backwards, and^ the broad end: of the ovoid is above. Its peri~> 8* 82 URINARY ORGANS. phery is smooth, so that one does not infer from an external exa- mination, the lobules or internal divisions. The excavation of the kidney, called its fissure, {hilum renale) occupies about one-third of its long diameter, is bevelled in front, and leads to the very interior of the gland; conducting its blood vessels and excretory duct, which have to pass through a quantity of cellular and adipose matter. The kidneys are generally of equal size, being about four inches long, and two wide; and each one weighs three or four ounces. They have no ligaments for keeping them in position, but depend for the latter upon the adjacent cellular adhesions and blood vessels. The kidney being destitute of a peritoneal coat, has a well marked capsule which envelops it entirely and penetrates into its fissure for some depth, where it is perforated with foramina for transmitting the blood vessels and the ureter. This capsule is white, semi-transparent, fibrous, strong, and elastic : it adheres to the surface of the kidney by delicate cellular and vascular fila- ments, which are so weak that they permit it to be stripped off without difficulty, and when so removed, some indications of a lobu- lated condition of the organ are seen. Of the Minute Structure of the Kidney.—The lobulated state of the kidney is well marked in the foetus; and some of the lower orders of animals, as the bullock exhibit it very clearly through life. In the human adult subject, by tearing the kidney up according to the superficial lines marking a tendency to the lobulated condition, it will be found that there are really about fifteen divisions of it, more or less, each of which constitutes a small kidney (Renculus.) When the kidney is cut open longitudinally, it obviously consists of two kinds of substance, differing in their situations, colour, con- sistence, and texture. The one making the periphery of the gland is called from its position Cortical, (Substantia Coriicalis, Glandu- losa,) while the other, being more internal, is designated as the Medullary or Tubular, {Substantia Medullaris; Tubulosa; Fi- brosa.) The Cortical or Secretory Substance forms the whole circum- ference of the kidney, and, on an average, is about two lines in thickness; but it is thicker at some points, as, from its internal face, processes converge towards the centre of the gland, which THE KIDNEYS. 83 separate the tubular part into as many distinct portions of a co- noidal shape. It is composed principally of arteries and veins ramifying, among small granular corpuscles (Corpora Malpighiana or Glomeruli) that are very distinct when viewed with a micro- scope. It tears with facility, thereby presenting this granular ap- pearance, and is of a dark or reddish brown colour, varying con- siderably, however, according to the cause of death. The Granular corpuscles which form the mass of the cortical or secretory substance, are, individually, imperfectly visible to the naked eye, and appear like rounded points. The celebrated Ruysch, who was distinguished for the success- of his injections, and for the acuteness of his vision, declared that they consisted wholly in the very fine extremities of arteries and veins having a penicillous arrangement; while Malpighi and Schum- lansky viewed them as purses or small sacs of a glandular cha- racter, specifically suited to secrete urine, and upon whose pari-. etes the blood vessels ramified. From these granuli or acini the: incipient extremities of the tubuli uriniferi they asserted take their. rise. The Tubular or Conoidal Substance, consists in from twelve to* eighteen conoidal fasciculi, say on an average fifteen {Pyramides Malpighianai) presenting their rounded bases towards the cortical matter, and enclosed in it, while their apices converge to the cen-, tral cavity of the kidney, the surface of which they form. The bodies of these, pyramids, as just mentioned, are separated by pro- cesses of the cortical matter; but their apices are. free, and.project from the internal surface of the kidney so as to resemble as many small nipples, whence they are called Papillas or Mammellas Renales. Frequently two of the pyramids coalesce so as to form but one papilla together; in such case the lattergenerally.prer serves a duplicate appearance. The papillas are arranged into three vertical rows, one before, one in the middle, and another be- hind ; those of the foremost row are turned backwards; those of the middle look inwards; and those behind look forwards. Not unfrequently, there is a small depression {foveola) on the very sum- mit of the papilla. The tubular part is of a lighter colour and harder than the cortical, but the difference in these respects.is not always manifest and sometimes is reversed. 84 URINARY ORGANS. The conoidal fasciculi may each be considered, along with its appertaining cortex, as a sort of distinct gland {Renculus,) or at least as a lobe; for upon them depends the lobulated appearance as stated of the kidney of a foetus, and of animals. Each cone, when analyzed, is found to consist in a collection of tubes {Ductus Uriniferi Bellini) converging from the circumference of the kid- ney to the apex of the papilla. These tubes are more numerous near the base of the cone, in consequence of their successive junc- tion subsequently in approaching the apex :* their terminating ori- fices, on the latter, appear like small pores, from which the urine can be squeezed in little drops. In the early part of the course of the ductus uriniferi, while they are still in the cortical matter, they are wound about in a very serpentine and tortuous manner, and are distinguished by the name of Cortical Canals, {Ductus Ferrenii.-f) They there commonly go alone, winding their way in the cortical substance until they reach its most interior face; they then become straight, form the medul- lary substance, and have the name of the conduits or uriniferous ducts of Bellini.J Some of the calculations on this subject are not a little curious. It was ascertained by Ferrein that in each of the conoidal fasciculi (Pyramides Malpighianai) there were, at least seven hundred subor- dinate cones or pyramids, Pyramides Ferrenii; and as the number of conoidal fasciculi is generally about fifteen, these pyramids would amount to ten thousand five hundred. Again, each of the subordi- nate pyramids {Pyramides Ferrenii) is composed of many hun- dred uriniferous tubes, and, by the observations of Eysenhardt,§ each of these tubes consists of twenty smaller ones. ' The cortical canals of Ferrein, it is believed by many, terminate at their peripheral extremity, by forming loops upon themselves, and anastomoses with contiguous similar canals.|| It is also held by some, as Wagner, that in addition to this mode of termination others of those canals end in caeca or blind extremities, which * Schumlansky, Diss, de Struct. Renum, Strasburg, 1788. t A. Ferrein; sur la Structure des reins et du foie. Mem. de Paris 1749. X L. Bellini, de Structura Renum Florence, 1662. § De Struct. Renum Obs. Micros. Berlin, 1818. | Miiller, Krause, Owen, Weber, See Muller's Physiol. 2nd ed. p. 496. THE KIDNEYS. 85 are either single or bifid. Should the observations in this respect turn out correct, the arrangement has been at least found more de- cided and frequent in the lower animals than in man. Huschke* and John Mullerf have denied the connexion of the Granular corpuscles with the Ducts of Ferrein. In opposition to this view, besides the testimony of preceding anatomists, we have a very good paper, by W. Bowman, of Kings' College, London,! showing by injections this connexion, and that the arteries and veins make there a tufted junction with one another. It appears that in the Boa Constrictor, there is a vena portarum to the kidney—some approach to which the last author considers to exist in the human subject. The Kidney receives from the aorta one or more branches, called the renal or emulgent arteries, which divide as they approach the fissure; and having got into the substance of the gland are distributed by innumerable twigs to all parts of it. The veins equal in number the arteries, and are somewhat larger. When both, or even one, of these systems of blood vessels is injected with wax and corroded, its branches are so abundant as to retain the form of the gland. In engaging in the fissure of the kidney, the arterial ramifications are in front, the veins in the middle, and the commencement of the ureter behind.§ The artery on the right side is longer than that on the left. The reverse is the case with the emulgent veins, as they empty into the vena cava ascendens. This arrangement is owing to the relative position of the aorta and the vena cava ascendens, as the first is on the left side of the spine, and the last on the right side. The arteries of the kidneys, in ramifying minutely through its structure, adopt the following arrangement. They first of all pass through the processes sent inwards from the cortical matter be- tween the Pyramids of Malpighi, or large cones, and, having got fairly into the cortical matter, they divide into very fine twigs, which form arcades around the bases of the pyramids of Ferrein, and pass between them.|| These arcades have anastomoses with * TJeber'die Textur der Neiren, Isis, 1828, p. 561. + De Gland Struct. Leips. 1830. J Transactions Royal Society, London, Part 1st, 1842. § This rule is subject to frequent variations, || Schumlansky. 86 URINARY ORGANS. each other, and their larger branches go almost exclusively to the cortical substance, but few of them being found on the tubular. The branches radiate from the convexities of the arches, so as to surround the base of each cone, and to penetrate to the surface of the kidney. Some of these branches terminate in corresponding veins, and others on the granular corpuscles, or acini. The con- nexion between the corpuscles and the arteries, has been compared to that between grapes and the stems on which they grow, so as to form a bunch. The veins penetrate the substance of the kidney, and have a similar distribution; but they are much larger than the arteries, and have free, large and numerous anastomoses. A con- nexion of the corpuscles with the veins is not quite evident, and, even if it does exist, remains yet to be proved; at least, in the opi- nion of some anatomists: the fact, however, is well established, that fine injections will readily pass from the veins into the tubuli uriniferi. Also air blown into the ureter will pass readily into the veins. In my own injections the corpuscles of Malpighi are seen very distinctly to be formed of convoluted arteries, I have not seen the veins under this arrangement, neither have I traced the cortical canals to these corpuscles or acini. From the concave side of the arterial arcades very fine capil- lary branches converge in company with the ducts of Bellini in a line with them, and penetrate to the surface of the papilla renalis. Upon this surface is made a highly attenuated capillary intertex- ture, the meshes of which surround the orifices of the tubuli urini- feri. The converging arteries anastomose across the tubuli, making elongated meshes. A similar arrangement of the veins takes place from their cortical branches and arcades, it being in company with the arterial arrangement. The facility of injecting these minute tubular arteries and veins has frequently given rise to the mistake of considering them as the tubuli uriniferi themselves; an error which has been pointedly marked out by Miiller.* The nerves of the kidneys come from the solar plexus of the sympathetic ; and adhering to the arteries cannot be traced very far through the glandular structure. The quantity of lymphatics is considerable. The kidneys are subject to a false position: in one instance, I * Physiol, p. 225. THE KIDNEYS. 87 found in a young female subject, one of the kidneys in the pelvis in front of the rectum. A similar case has been seen by Professor Hensinger.* I have met with several instances of a coalition across the spine, of the two kidneys, so as to present the appear- ance of a bilobed organ. Of the Excretory Duct of the Kidney, or the Ureter. The Ureter is a canal which conveys the urine from the kidney to the bladder. It commences in the centre of the kidney by an enlargement called pelvis, which branches off into three or four portions, '{calices,) one above, one below, and one or two inter- mediate. Each of these calices, is divided, at its free extremity, into three or four short funnel-shaped terminations, {Infundibula.) Each of these terminations embraces by its expanded orifice, the base of a papilla, so as to permit the latter to project into it, and thereby to' distil its urine there. Very frequently the number of papillas exceeds that of the infundibula, in which case two of the former project into one of the latter. The pelvis of the kidney having emerged at the fissure behind the vessels, from being expanded and conoidal in shape is reduced to a cylindrical canal, which, properly speaking, is the ureter: the latter is about the size of a goose-quill, and descends through the lumbar region, between the peritoneum, and the psoas magnus muscle. It dips into the pelvis by crossing in front of the primi- tive iliac vessels and the internal iliac, crosses the vas deferens at the back of the bladder, and penetrating obliquely the coats of the latter, terminates in an orifice ten or twelve lines behind that of the neck of the bladder. The excretory duct of the kidney is formed by two coats. The external is a dense, fibrous, and cellular tissue, but is destitute of any thing like muscle. The internal is a thin mucous lamina, which can be raised up without much difficulty, and is continuous, at its lower end, with the internal coat of the bladder; at the upper end, it is supposed by some anatomists to be. reflected over the papillae, and even to pass for some distance into the tubuli uriniferi. This duct has considerable powers of extension, as manifested by its transmitting large calculi from the kidney, and also, by its * Amer. Med. Jour., Vol. iii. p. 442. 88 URINARY ORGANS. general enlargement in some cases of obstructed urethra; its sen- sibility is exquisite when irritated by a calculus passing down it. The walls of the tubuli uriniferi are the surface upon which the secretion of urine most probably takes place exclusively. The mucous membrane of the pelvis of the kidney being continued over them so as to form the surface; these canals, delicate as they are, are said to exhibit an epithelium formed of nucleated cells. Of the Renal Capsules. The Renal Capsules {Capsular Renales, Renes Succenturiali,) are two small bodies, one on either side, placed upon the upper end of the kidney. They are of a yellowish brown colour tinged with red, have no excretory ducts, and are more distinctly deve- loped and softer in the perfect foetus than in the adult; whence they are ranked among those organs, as the thymus gland, and others; which, having some peculiar value in foetal existence, are perhaps unnecessary to that of the adult.* They are of a trian- gular pyramidal shape, flattened before and behind, and rest by a concave base upon the kidney; they are about fifteen lines high and as many wide. They are surrounded by a proper coat of lamellated dense cel- lular tissue, which, by detaching inwards its prolongations, keeps the parts of these bodies together, and marks out their divisions. In the centre of the renal capsule, a cavity may, from time to time, be found; but, according to my own observations, nothing in our structure is less certain than its existence; and, in the opi- nion of Meckel, when found, it is the result of cadaverous decom- position. In the foetus it contains a reddish viscid fluid, which seems to consist in a large share of albumen, as it coagulates with alcohol; in children, this fluid becomes yellow: in adults it is dark brown; and in old people it is either entirely deficient, or in a re- markably small quantity. Of the Minute Structure of the Capsular Renales.—The arteries of these bodies come from the emulgents, from the phrenics, and from the aorta. The veins of the right one terminate in the cava * This opinion has been confirmed in a dissection of a foetus, where I found the capsulae renales, though the kidneys were absent* THE RENALE CAPSULES. 89 ascendens, and of the left in the left emulgent. Each one is divi- sible into lobes, and by a slight maceration may be reduced into lobules and small granulations. The granulations seem to have an intimate connexion with the veins, as they are easily penetrated by fluid injections from the latter. The external part is rather more consistent and yellow than the internal; hence, a division has been adopted into cortical and medullary portions. In the cortical portion the minute arteries and veins are about the size of the capillaries of other parts, and are of nearly uniform magnitude. They are arranged in a radiated manner, so as to run in lines from the surface towards the centre. The arteries anastomose with the adjoining branches, so as to form very long meshes: the veins do the same. On the periphery of the organ there is an ordinary capillary net-work of vessels. A spongy venous tissue composes the greater part of the medullary or more interior portion; this spongy tissue receives the radiated venous branches of the exterior, and discharges its own blood into a large vein (Vena supra-renalis) in the interior of the organ. Miiller,* in addition to the above, says that the only cavity in this organ is the vein just alluded to, and that by forcing air into the vein the whole medullary tissue may be distended. Examination with the microscope, by Mr. Gulliver,f exhibited the proper structure or pulp as formed of spherules, from the 24-roo- to the ^o of an inch. Alleged excretory ducts for these bodies have been found going to the testicle, to the pelvis of the kidney, and to the thoracic duct, but no credit is now attached to such assertions. Corpora Wolffian a. The Corpora Wolffiana, called after their discoverer, are small bodies found only in the earlier stages of foetal life, and of which there are scarcely any traces at the end of the fifth month. When in full development they are so large as to conceal the kidneys and the supra renal capsules, but as these latter organs grow the cor- pora Wolffiana diminish, and are finally placed lower down. They are supposed to be vicarious kidneys for the time, and they consist in * Physiol., p. 621. t Gerber's General Anatomy, Appendix, p. 103. London, 1842. Vol. II.—9 90 URINARY ORGANS. transverse ccecal tubes, which are numerous. They have each an excretory duct, which leads from their lower part into the Sinus Uro-genitalis. The latter is also peculiar to the foetal state, and is a tube which for the time receives the ureters, the vasa effe- rentia, the ducts of the corpora Wolffiana; and is prolonged into the urachus. The Sinus Uro-genitalis is finally divided into two branches, from one of which is evolved the urinary bladder, and from the other the vesiculae seminales.* Of the. Bladder. The Bladder {Vesica Urinaria,) is the reservoir for the urine, and is placed in the pelvis, just behind the symphysis of the pubes. When pressed upon, as it commonly is, by the adjacent viscera, it is flattened somewhat before and behind; but removed from the body and inflated, it is an elongated sphere or an oval; the great- est diameter of which is vertical, in regard to the linea ileo-pec- tinea. The superior end of the bladder is called the upper fundus, and the lower end the inferior fundus; the latter is rather more obtuse than the other; and between the two is the body. The neck of the bladder is its place of junction with the urethra. The form of the bladder is influenced by age and by sex; in very young infants it is cylindroid, and owing to the smallness of the pelvis, rises up almost wholly into the abdomen. In the adult woman, who has frequently borne children, it is nearly spherical, has its greatest diameter transverse,! and is more capacious than in man. The bladder is bounded in front by the pubes, above by the small intestine, behind by the rectum, and below by the prostate gland and the vesiculae seminales. From its superior end there proceeds to the umbilicus a long conical ligament, the urachus, which is placed between the linea alba and the peritoneum, and produces a slight elevation or doubling of the latter. In mankind, the urachus is solid; but some very rare cases are reported, in which it has been hollow, so as to permit the urine to flow through it from the bladder. This anomalous conformation has generally been attended with a congenital obstruction of the urethra.J When * Mailer's Phys., p. 1639. t H. Cloquet, Anat. Descrip. t Sabatier, Anat., vol. iii. p. 19. THE BLADDER. 91 the anterior parietes of the abdomen are put upon the stretch, a semi-lunar fold of the peritoneum, as formerly mentioned, is seen to proceed, on either side of the urachus, from the lateral surface of the bladder almost to the umbilicus. These folds contain, in their free edge, the fibrous remains of the umbilical arteries of the foetus, called, subsequently to uterine life, the Round Liga- ments of the bladder, though they have little or no influence on its position. The bladder is also fixed in its situation by the pelvic aponeurosis, a membrane elsewhere described with the organs of generation. The bladder consists of four coats: the Peritoneal, the Muscu- lar, the Cellular, and the Mucous. The Peritoneal Coat is very imperfect, and is derived from the part of the peritoneum which descends from the anterior parietes of the abdomen into the pelvis. It covers the upper and the pos- terior face of the bladder, and then passes to the rectum, by sink- ing down between these two organs, so as to form the small pouch beneath the lower fundus of the bladder; the apex of this pouch reaches within an inch of the base of the prostate. The upper margin of this pouch next to the bladder, forms a strong horizon- tal doubling, stretching across the pelvis, when the rectum is empty, and is on a level with the posterior end of the vesiculas seminales. Being connected to the subjacent muscular coat by a thin lamina of loose cellular membrane, the peritoneum may be dissected off without difficulty. In considerable distentions of the bladder, it is reflected from the upper end of the latter to the abdominal mus- cles in a line much above the pubes; whereby a good opportunity is afforded of reaching, with an instrument, the cavity of the blad- der without injuring the peritoneum. The Muscular Coat is of a thickness intermediate to that of the stomach and of the oesophagus, and its fibres are pale. They pass in very varied directions,* and are collected into flattened fasciculi, leaving interstices between them, through which the internal coat is occasionally caused to protrude, in strictures and other obstruc- tions of the urethra. Many of these fasciculi, arise about the neck of the bladder, and ascending upwards, before, behind, and laterally, terminate at the superior fundus in the base of the urachus. Within * Santorini, Septemd. Tabul. 92 URINARY ORGANS. these, which may be considered as the longitudinal fibres of the bladder, there are others forming a thinner lamina, whose course is transverse, or oblique : they serve to connect the preceding. As the muscular fibres are collected at the neck of the bladder, and at the urachus, there is, of course, an increased thickness at these points. The Cellular Coat {Tunica propria) like that of, the alimentary canal consists in a close, dense, lamellated, and filamentous cellu- lar tissue, very extensible and difficult to tear. It is impervious to water, adheres closely to the muscular coat without, and to the mucous within, so as to form a strong bond of union between them. It is pervaded by many vessels and nerves, which it conveys to the mucous coat. The Mucous Coat is also called the villous, but is much more smooth than the corresponding one of the stomach. It is white, with a slight tinge of red, and abounds with mucous follicles, which, though small and scarcely discernible in a natural state, are rendered very obvious by disease. It stretches with much fa- cility, but, like other mucous membranes, does not restore itself fully, and is rather thrown in the contracted state of the bladder, into wrinkles or folds, having a diversified course, and of a fugi- tive character, as they disappear again upon the next distention. It is very vascular. The internal face of this coat presents, at its inferior part, the following appearances: 1. The Vesical Triangle {Trigonus Lieutaudi, Trigone Vesicale) is placed immediately behind and below the neck of the bladder, occupying the space between it and the orifices of the ureters. It is an equilateral triangle of an inch in length, its surface is smooth, is not affected very materially in extent either by the dilatation or the contraction of the bladder, and is elevated so as to be suffi- ciently distinct and well defined. 2. The anterior angle of the triangle looks into the orifice of the urethra, and is generally so elevated that it has obtained the name of Uvula Vesicas; it is, however, simply a projection of the mu- cous membrane depending upon the subjacent third lobe of the pros- tate ; which, at this point, is not unfrequently much enlarged in the THE BLADDER. 93 aged, and then presents a great difficulty in the introduction of a catheter. 3. The Orifices of the ureters form the posterior angles of the triangle, and are contracted somewhat below the size of the canals themselves. They are said by Sir Charles Bell,* to be furnished, each one, with a small fasciculus of muscular fibres, which runs backwards from the orifice of the urethra, just beneath the lateral margins of the triangle, and, in its contraction, will stretch the ori- fice of the ureter so as to permit an easy passage of the urine into the bladder. The retrogradation of the urine is prevented by the ureter passing obliquely, for six or eight lines, between the muscu- lar and the mucous coat; there is something also in the obliquity of the orifice itself which assists in this effect; as I have ascertained by removing the muscular coat entirely, at this point, and dissect- ing up the ureter, notwithstanding which, the bladder, when in- flated, still retained its contents. Where the ureter penetrates the muscular coat, there is often found a layer of longitudinal muscular fibres ascending and enveloping it for half an inch, or an inch. 4. The Inferior Fundus of the bladder {Bas-fond of the French) is a depression of the general concavity of the bladder, of about six lines in depth, placed between the base of the vesical triangle and the posterior side of the bladder. In the erect position, calcu- lus, when present, lodges there. 5. The Internal Orifice of the neck of the bladder resembles strongly that of a Florence flask, modified, however, by the pro- jection of the uvula vesicae, which makes it somewhat crescentic below. The neck of the bladder penetrates the prostate gland, but, at its commencement, is surrounded by loose cellular tissue containing a very large and abundant plexus of veins.f The in- ternal layer of muscular fibres is here transverse ; and they cross and intermix with each other in different directions, forming a close compact tissue, which has the effect of a particular apparatus for retaining the urine, and is called Musculus Sphincter Vesicae * Med. Chir. Trans. Vol. iii. t Mascagni, Anat. Univ. Str. Prim. Tab. Spec. Fig. V. 9* 94 URINARY ORGANS. Urinariae. Generally, anatomists have not considered this struc- ture as distinct from the muscular coat at large; but Sir Charles Bell, late Professor in the University of Edinburgh, whose reputa- tion as an anatomist is well established, gives the following account of it. " Begin the dissection by taking off the inner membrane of the bladder from around the orifice of the urethra. A set of fibres will be discovered, on the lower half of the orifice, which, being care- fully dissected, will be found to run in a semicircular form round the urethra. These fibres make a band of about half an inch in breadth, particularly strong on the lower part of the opening, and, having mounted a little above the orifice, on each side, they dis- pose of a portion of their fibres in the substance of the bladder. A smaller and somewhat weaker set of fibres will be seen to complete their course, surrounding the orifice on the upper part; to these sphincter fibres a bridle is joined, which comes from the union of the muscles of the ureters."* After repeated observations on this point, I have come to the conclusion that Mr. Bell has indicated a real structure; but my own dissections have resulted as follows: The inferior semicir- cumference of the neck of the bladder is defined by a thick fasci- culus of muscular fibre, half an inch wide, running in a transverse direction, and having its ends attached to the lateral lobes of the Prostate Gland, being above the third lobe of the latter. This fas- ciculus is perfectly distinct from the ordinary muscular fibre of the bladder, and resembles in its texture the musculo-fibrous coat of the arteries. The superior semicircumference is also surrounded by a thin layer of muscular fibres of an ordinary kind, forming a broad, thin band of a crescentic shape, the lower ends of which are insen- sibly lost in the adjacent muscular coat of the bladder by being spread out. And, lastly, beneath the mucous membrane of the ve- sical triangle, there is a triangular muscle of the same size as the vesical triangle. Having elongated angles, the anterior angle may be traced to the posterior part of the caput gallinaginis, and the posterior angles to the orifices of the ureters and the adjacent part of the bladder. The texture of this muscle is, also, like that of the musculo-fibrous coat of the arteries. When a bladder is recent, this detail of structure is made out with difficulty : it re- * Diseases of the Urethra, &c, p. 10. Lond. 1820. THE BLADDER. 95 quires to be previously hardened in spirits of wine. That a power exists in the neck of the bladder of retaining completely the urine, has been satisfactorily demonstrated to me in a case of fis- tula in perineo, which was presented to the notice of the late Dr. Physick and myself, some years ago.* Occasionally there exists on each side of the neck of the blad- der, passing from it to the pubes, a muscle of half an inch in breadth, the effect of which is to draw the neck of the bladder towards the symphysis pubis. This, called by some the muscle of Wilson, or the Compressor Urethras has also an influence in retaining the urine. When it exists in a distinct state it is evidently, the anterior fasciculus more detached than usual of the Levator Ani; but under ordinary circumstances it appears as the anterior margin of that muscle, and therefore does not attract special attention. As the urethra of the male performs the double office of con- ducting both semen and urine, it will be described more properly along with the organs of generation. The urine has a considerable number of constituents, the pro- portion of which varies according to age, health, and other cir- cumstances. Water forms about nine-tenths of it, the remainder is an animal matter insoluble in alcohol; uric and lactic acids; lactate of ammonia; sulphate of potash and of soda; hydrochlorate of soda and of ammonia; phosphate of soda and of lime; and fluate of lime. * Chapman's Med. and Phys. Journ. 1824, BOOK VI- ORGANS OF GENERATION. CHAPTER I. Of the Organs of Generation in the Male. The Male Organs of Generation consist in the Testicles and in the Penis, with their appendages; or, in the language of some anatomists, in the Formative and in the Copulative Organs; which distinction has been applied to both sexes. SECT. I.--OF THE PENIS. The Penis, {Membrum Virile, Menlula,) from performing the two offices, one of which is the conducting of urine from the blad- der, and the other the projection of semen into the female, has accordingly, a peculiarity of structure, which allows it to assume a state of collapse or of erection. Its shape is almost cylindrical, but terminating in front by an obtusely pointed extremity, named Glans. It adheres by its posterior end or root to the bones of the pelvis, at and below the symphysis pubis. It is formed by common integuments, by condensed cellular tissue, by the Corpus Cavernosum, and by the Corpus Spon- giosum. The skin on the penis is more thin and delicate than it is on most other parts of the body, and is furnished with a considerable 98 ORGANS OF GENERATION. number of sebaceous follicles or glands about the root of the organ, with hairs growing from the centre of them. This same skin, in passing to the abdomen over the pubes, is somewhat protruded by a subjacent deposite of fat and cellular matter, causing an appear- ance corresponding with the mons veneris of the female; and is also generally thickly covered with short curly hair, which, as the individual advances in life, proceeds in a pointed direction to the umbilicus. The skin of the penis is but loosely connected to the organ, so that it slides readily backwards and forwards, and by its elasticity is well suited to the varying states of erection and collapse. At the anterior extremity it is thrown into a duplicature or fold, the prepuce, {Praputium;) the internal lamina of which being fixed circularly to the penis, some distance back from the point, permits a considerable portion of that extremity of the penis, called the Glans, to project when the prepuce is drawn back. The under middle part of the prepuce is attached to the extremity of the glans by a vertical longitudinal duplicature, called the Frasnum, which extends to the orifice of the urethra. The skin does not actually stop at the circumference of the glans, but is continued smoothly over it, modified, however, so much in its structure, as to be much more adherent, soft, delicate, vascular, and sentient: its cuticle there is a thin epithelium, readily separated by maceration. The projecting circular and oblique shoulder of the glans, behind which the skin becomes firmly joined to the penis, is called the Crown {Corona Glandis.) The con- tracted portion, behind the corona, is the Neck (Collum.) On the surface of the neck and the posterior face of the corona, the skin is furnished with an abundance of small glandular masses or folli- cles, {Glandular Odorifera Tysoni,) which secrete the thick white sebaceous matter, {Smegma praputii,) that accumulates when per- sonal cleanliness is not attended to. The penis, in addition to other modes of attachment to the bones of the pelvis, is fixed by the Ligamentum Suspensorium. The latter is a triangular vertical fibrous lamina, which proceeds down- wards from the symphysis pubes to the dorsum of the penis; and, according to Mr. Colles, envelops this organ to the glans, forming its cellular coat, and being continued into the fascia superficialis abdominis. Posteriorly, it is lost insensibly on the fascia of the thighs, covering the adductor muscles. At its origin it is occa- THE PENIS. 99 sionally furnished with muscular fibres; one strongly marked in- stance of which has been presented to me in my own dissections. The Corpus Cavernosum of the penis, forms by much the most considerable portion of the whole organ. Externally, it is a white fibrous membrane, of a dense structure, enjoying extensibility and an extreme degree of contractility. This coat of the penis is oc- casionally called its elastic ligament. Its external fibres pass, for the most part, longitudinally, except about the root, where they are blended with the periosteum of the bone, and with the tendons of the muscles. It arises by two conical crura, from the internal face of the crura of the pubes and ischia, to within a little distance of the anterior part of the tuber ischii. At the lower part of the symphysis pubis these crura join and form a body; which, when stripped of its connexions, resembles two cylinders united, lying alongside of each other; and which terminate in common, ante- riorly, by a truncated cone, covered obliquely by the glans. At the posterior part of the corpus cavernosum, in its centre, there is a septum, almost complete, also of the same elastic substance, which separates the two halves from each other; but, anteriorly, this septum is more imperfect, having an arrangement like the teeth of a comb, whence the term Septum Pectiniforme has been given it. This septum is continued at its margins into a layer of circular fibres, constituting the internal coat of the corpus caver- nosum. In the middle of the corpus cavernosum, above, is a longitudinal depression for lodging the veins of the penis, and, in the same man- ner, there is another below, for the corpus spongiosum urethras. The cavity of this membrane is filled by a spongy tissue, that arises from its internal face, and is formed of filaments and little laminae; they, by crossing each other, make a multitude of cells, which have a perfectly free communication with one another, and generally are somewhat occupied by blood. A fine injection through the artery of the corpus cavernosum will fill these cells and return through the veins; from which cause the cells may be considered as intermediate to the two orders of vessels. This opinion is the more probable from the cells being lined by a thin membrane like the internal one of the veins, and which is easily seen near the septum by tearing the spongy part from it. 100 ORGANS OF GENERATION. The Corpus Spongiosum Urethras extends from ten or twelve lines behind the junction of the crura of the corpus cavernosum, to the anterior extremity of the penis. Externally, it has a coat resembling that of the corpus cavernosum, except that it is thin- ner, and in its centre is the canal for the passage of urine. Be- tween the canal and the coat is a spongy structure, much finer than that of the corpus cavernosum, and though the cells commu- nicate freely, still they have the appearance of convoluted veins. The corpus spongiosum is not of equal diameter in its whole course, for its commencement in the perineum, where it is pendulous, is enlarged into what is termed the Bulb; from this it diminishes gra- dually to the anterior end, where it is again enlarged into the glans penis. This internal cellular structure of the corpus cavernosum is pro- bably formed, almost exclusively, by the internal coat of the dilated veins, partially sustained by the above filamentous and laminated bands, for the purpose of strengthening the arrangement. The adhesion of this structure at large to the corpus cavernosum is much weaker than one may suppose, as it is very easy to peel or roll it off almost without dissection, thus leaving the elastic liga- ment of the corpus cavernosum perfectly free. In the case of the corpus spongiosum, the cellular structure, though analogous in tex- ture to the above, does not peel off so easily. Miiller* has made the assertion that there are two modes of arterial termination in this erectile or cellular structure of the penis, one by direct connexion with the incipient ramuscles of the veins, and the other, by tufts of coeca bent backwards on themselves, and, which he has named Helicine arteries (Arter. Helicinae.) Project- ing as they do into the venous cells, he declares that though no openings from them can be discovered, yet the latter exist so as to fill the cells in erection. These singular arteries are found prin- cipally in the back part of the corpus cavernosum and spongio- sum, and are seen after a minute size injection of the arteries of the penis, when the cells have been filled by washing the size from the cells.f * Elem. Physiol, vol. i., p. 252. Lond., 1840. t Professor Valentin, see Muller's Archives for 1838, denies the existence of the arteriae helicinae. THE PENIS. 101 The Urethra is a mucous canal, whose length varies according to the degree of erection in the penis, and extends from the neck of the bladder to the extremity of the glans. It is difficult to as- sign a fixed length to the canal of the urethra, owing to the varia- ble size of the penis in different persons, and in the same indivi- dual, depending upon his general vigour and also period of life. The measurements of Professor Pancoast* in the black and mulatto, show an average of about seven inches from the neck of the blad- der to the end of the urethra in the unstrelched state, and about an inch more in stretching the organ moderately. It is, however, well known that the sexual organs of the black are larger, both male and female, than the white. The urethra is curved, and receives in its course the ductus ejaculatorii, the excretory ducts of Couper's glands, and the mu- cous lacunae of its own internal membrane. The first part of this canal which traverses the prostate gland is from fifteen to eighteen lines in length, and is called the Prostatic Portion: it is well sup- ported by this body, although its own sides are very thin. On its inferior surface is a doubling which constitutes the Verumontanum or Caput Gallinaginis. On either side of the caput gallinaginis the canal of the urethra is depressed into something like an oblong cul-de-sac or narrow trench, where are to be found the lacunae of the prostate gland. Between the Prostate and the Bulb is the membranous part of the urethra, about eight or ten lines long; it is unprotected, except by a soft covering, which seems in some measure to be a mixture of gelatinous matter and muscular fibre. The former was consi- dered by Littre as a glandular body which secreted a viscid humour into the interior of the canal; the latter, probably, is the part de- scribed by Winslow as the inferior prostatic muscle; which he asserted to arise on each side of the membranous part of the ure- thra, and to be inserted into the corresponding branch of the pubes near the symphysis. The membranous part of the urethra does not get into the end of the bulb, but penetrates it from above, half an inch or more occasionally, from its extremity, just below the junction of the crura of the corpus cavernosum. The canal varies in its diameters: at its commencement, which is synonymous with the neck of the bladder, it is large; it then » Wistar's Anat. 8th Edit., vol. ii., p. 170. Vol. II.—10 102 ORGANS OF GENERATION. contracts at the back of the caput gallinaginis, and immediately enlarges in the fore part of the prostate, at the sides of the caput. The membranous part is small; the canal then enlarges in the bulb. In the body of the penis the canal is successively diminished, till it comes almost to the glans, when it is so remarkably enlarged again as to get the name of Fossa Navicularis; it terminates, finally, by a short vertical slit at the extremity of the glans. The canal of the urethra is formed of a very thin mucous mem- brane, on the outside of which is a dense filamentous cellular sub- stance possessing much extensibility, contractility and elasticity. The mucous membrane has great vascularity, and its veins are so superficial that they frequently bleed freely upon the introduction of an instrument into the bladder, it is also very sensitive. The cellular coat on its outside, whereby it adheres to the spongy struc- ture, contracts sometimes in such a manner that circular fascicu- lated ridges simulating the presence of circular muscular fibres are seen shining through the mucous coat, though when the mu- cous coat is peeled off this arrangement disappears. In the whole length of the canal there are two folds or lines, one above, and the other below; and in the membranous and spongy portions, excepting the fossa navicularis, longitudinal folds of the mucous membrane also exist, which are effaced by distention. The fossa navicularis sometimes exhibits in the contracted penis, hardened in spirits of wine, very superficial folds of the mucous membrane almost transverse, in the narrow depressions between which we see the orifices of very fine mucous follicles. In the upper part of the canal there are a great many mucous lacunae;* Loder has marked about sixty-five: there is one parti- cularly large in the upper surface of the fossa navicularis, which, it is said, has stopped the point of a bougie, and been mistaken for stricture.f Mr. Shaw has described a set of vessels immediately on the out- side of the internal membrane of the urethra; which, when empty, are very similar in appearance to muscular fibres. He says, he has discovered that these vessels form an internal spongy body, * Tabula Anat. t Sir Everard Home formerly communicated to the Royal Society a highly intc- resting paper on the structure of the lining membrane of the urethra. From his microscopical observations he was induced to think that it is muscular. MUCOUS GLANDS. 103 which passes down to the membranous part of the urethra, and forms even a small bulb there.* His preparation, being a quick- silver injection of the part, is certainly a very satisfactory demon- stration of its existence; yet, in my own observations, where the blow-pipe has been resorted to, it has rather appeared to me to be the cellular membrane connecting the canal of the urethra with the corpus spongiosum. The arteries of the penis come from the internal pudic; some of its veins follow the course of the arteries, and others collect into the two venae dorsales penis; the nerves come from the Superior and Inferior Pudendal. SECT. II.—OF THE MUCOUS GLANDS AND APPARATUS. The Seminal Vesicles {Vesicular Seminales) are two convoluted tubes, one on each side, two inches in length, placed on the lower fundus of the bladder, between it and the rectum, and behind the prostale gland. At their anterior extremities they approach very nearly to each other, being only separated by the intervention of the vasa deferentia. They are fixed to the bladder, and sur- rounded by a thick mass of adipose and cellular matter, with many blood vessels, principally veins, passing through it. When inflated and dried, they present the semblance of cells, but are, in fact, long tubes; which being convoluted, are reduced to the apparent dimensions mentioned. When dissected and stretched out, they are four or five inches long, by three lines in diameter. There are also several pouches on each side of the long tube which increase the number of cells. The convolutions are pre- served by the intermediate cellular tissue. These bodies consist of two coats: an external, which is a condensed fibro-cellular sub- stance; and an internal, which is mucous, being a continuation of the lining membrane of the urethra. The excretory duct of each vesicle is about a line and a half long, when it joins in the sub- stance of the prostate with the vas deferens of the same side; a « Med. Chir. Trans, vol. x. 104 ORGANS OF GENEP..ATION. common canal (ductus ejaculatorius) is thus formed, which runs parallel with its fellow, below the urethra.* The Ductus Ejaculatorius is about eight or ten lines long, and opens by an oblong orifice, on the anterior margin of the Caput Gallinaginis : it is larger behind than before, which gives it a coni- cal shape, and allows fluids injected to pass freely from the vas deferens to the vesicula seminalis, and the reverse. The vesiculae are commonly filled by a drab-coloured thick fluid, supposed to be a mixture of the semen, with their own proper secretion, though, of this, Mr. Hunterf doubted, inasmuch as he found them equally well filled in cases where the testicle of the corresponding side had been lost, and therefore he concluded that they were not indebted to the secretion of the testicle for their contents. The discovery, latterly, of spermatic animalcules in the fluid contained after death in the vesiculae is considered now as proof sufficient of their being reservoirs of the male semen along with their own secretion, as these animalcules were most probably conveyed there along with the semen. The Prostate Gland {Glandula Parastata) is a body about the size and form of a horse chestnut, fixed on the neck of the bladder, and penetrated by the urethra, which traverses it much nearer its superior than its inferior surface. The base of it is turned back- wards, and the point upwards; its inferior surface rests upon the rectum; it is rendered concave by that circumstance, and its sides, in the distentions of this organ by fasces, are overlapped by it. The Prostate has, posteriorly, a notch in its centre, which divides it into two lateral lobes, and by raising the Vesiculae Seminales, we see where their excretory ducts penetrate the gland, and separate from the body of it, the little tubercle, to which Sir Everard HomeJ has particularly called the attention of the profession, and con- sidered as a Third Lobe; it being certain that it is frequently the seat of disease and tumefaction. On the under surface of the canal formed in the prostate, by the * In a, dissection executed at the University by Dr. Joseph Togno, a muscle was found on the inferior surface of the seminal vesicles arising from the prostate gland, and inserted into them. This is said to be a common arrangement in some ani- mals. t Observations on the Animal fficonomy. t Diseases of Prostate. PR06TATE GLAND. 105 urethra, is, as mentioned, the oblong elevation called the Verumon- tanum, or Caput Gallinaginis. It commences a little in front of the uvula vesicae, and, being broader and higher behind, comes to a point very gradually before; it is about eight or ten lines long. Along the posterior part of this ridge a long cleft is sometimes found, it being the orifice of a lacuna, first observed by Morgagni; and in front are the orifices, bordering upon each other, of the ductus ejaculatorii. Very superficial folds of the lining mem- brane, some three or four in number, radiate from the anterior end of the caput to the anterior end of the membranous portion of the urethra. The prostate consists in a condensed, white, extensible, though easily lacerated fibrous cellular tissue, within which are placed a great number of mucous canals, that have from eight to twelve ducts, or, according to Loder, from thirty-two to forty-four, pass- ing obliquely forwards, and terminating in the urethra, as stated, at the sides of the urethral crest, or caput gallinaginis. It is an aggregation of smaller glands, like the mamma or any other com- posite gland; the principal ducts are, therefore, formed by the convergence of branches in successive junction. The fluid se- creted is thick, ropy, white, and semi-transparent, in a healthy state. The prostate is surrounded by a fibrous capsule, to be described. The lacunas of the third lobe penetrate the coats of the bladder, behind the caput gallinaginis. Of the Glands of Couper.—These glands are also intended for the secretion of mucus, or a fluid very much like it, into the canal of the urethra. They are two in number, one on each side, and are situated in advance of the prostate, between the laminae of the triangular ligament, at the point where the bulb of the urethra ad- heres to it. Commonly, they are about the size of a garden pea, but not unfrequently much smaller, and, in some instances, cannot be found at all, which induced Hiester to declare, that he had searched for them fruitlessly. They are yellowish, hard, and con- sist of several lobules united together. Each one has an excretory duct that receives readily a bristle, and passes obliquely forwards. between the corpus spongiosum and the canal of the urethra, to terminate in an oblique orifice in the latter, about an inch distant from the gland. 10* 106 ORGANS OF GENERATION. One or more glands, of the same description, and discovered by Littre, are occasionally found just in front of Couper's. They also discharge their secretion into the adjacent part of the urethra. In my own dissections I have not met with them. SECT. III.—OF THE TESTICLES. The Testicles (Testes, Didymi) are two in number, one for each side of the scrotum. Being the seat of the secretion of sperm or the male prolific liquor, their function is of the first importance in the act of generation. They are of an oblong oval form, some- what compressed laterally; and present their edges forward and backward. From being suspended near the middle of their pos- terior edge by the spermatic chord, the upper end points somewhat forward, while the lower one is directed in the same degree back- ward. They are about an inch and a half long, by one inch in breadth, and eight or nine lines in thickness. They are of equal size generally, but in case of a difference it is in favour of the right; the latter is also remarkable for being suspended higher than the left, a feature in ancient statuary so universal, as to prove the vigilance and accuracy of the sculptors of those days, in re- gard to the proportions and peculiarities of the human form. "Two obvious advantages attend this arrangement: one, that of the testicles passing each other without the collision when the thighs are brought together; and another, the facility of keeping the penis to one side, instead of straight forward in the middle line of the body."* The testicle is enveloped by several tunics; they are the Scro- tum, the Dartos, the Tunica Vaginalis, and the Tunica Albuginea. The Scrotum is merely a continuation of the common skin from the inner side of the thighs, the perineum, and the penis, and is common to the two testicles. It is a symmetrical bag, and the two halves aro marked off from each other by a middle line or elevation of the skin, called the Raphe, which begins in the peri- neum at the anus, and, winding around the scrotum, is continued along the under surface of the penis to the prepuce. * Sir A. Cooper on the Testis. 1830. THE TESTICLES. 107 The skin of the scrotum is thin, darker than elsewhere, but has a thick, strong epidermis; it has many sebaceous follicles in it, and is sparingly furnished with hair. It is very extensible, as manifested in fatigue, and by hydrocele; and may be contracted again so as to draw the testicles close under the pubes, though for the latter power it principally depends upon the subjacent coat. Its surface is covered with wrinkles, for the most part transverse, and ending at the raphe: they are effaced during its great dis- tentions in hernia and dropsy, and then it has a smooth shining surface. The Darios is placed within the scrotum, and forms two distinct sacs or tunics, one for each testicle. It arises from the inferior margins of the crura of the ischia and of the pubes, and lines the scrotum till it reaches the raphe; it is then reflected upwards to form the partition between the testicles, (septum scroti,) and ter- minates at the corpus spongiosum urethras. This membrane, ac- cording to the observations of MM. Chaussier, Lobstein, and Breschet,* does not exist in the scrotum till the descent of the tes-: tide, and then appears to be an expansion of the gubernaculum testis. It receives a considerable number of blood vessels, which, owing to the thinness of the skin, may be seen in the living body, ramify- ing through its substance: its general appearance is, therefore, reddish. It is destitute of fat, and consists in long fibres much matted together, and passing in every direction: they are easily separated by distention with air or water, and by slight macera- tion. Its powers of contraction are exceedingly well marked upon the application of cold to the scrotum, from which cause it has been considered by many anatomists as muscular: the only dis- tinct evidences, however, which I have met with of a resemblance to the latter, have been found generally on its posterior face, near the perineum.f From its equivocal character, J. F. Meckel has very ingeniously suggested that it forms the transition from cellu- lar to muscular tissue, and that there exists between it and other muscles the same relation that there is between the muscles.of the * Dictionnaire des Sciences Med., tome viii. t Since the first edition, I have dissected one subject, (January, 1830,) where the, fibres were evidently muscular, though interwoven. 108 ORGANS OF GENERATION. superior and of the inferior orders of animate. Among the latter, the fibrous structure is indistinctly marked, and is masked by gela- tine; an element of the cellular tissue which envelops and con- ceals the fibrine, an element of the muscular tissue. The fibres of the cremaster muscle, which are next in order, form a very imperfect covering to the testicle, and belong rather to the spermatic chord: what remains to be said concerning them will be more properly introduced into the account of the latter. The cellular substance that connects the dartos and the cremaster with the tunica vaginalis forms a compact and perfect lamina, sometimes spoken of as the Tunica Vaginalis Communis Testis. There is one for each testicle, which it surrounds entirely, as well as its chord, and connects the chord to the margin of the external abdominal ring, as stated in the account of the latter. At its upper end it is continuous with the cellular substance that unites the peritoneum to the parietes of the abdomen, as may be proved by inflating it, when the air will penetrate accordingly through the abdominal canal. The Peritestis, or Tunica Vaginalis, was originally a process of peritoneum, communicating with the cavity of the latter through the abdominal canal; but in the adult, it appears as a complete and distinct sac. As it is very rigidly comparable to a double night-cap drawn over the head, we accordingly find that the testi- ticle, along with the epididymis is pushed into it from behind. That portion of the tunica vaginalis which is in contact with the testicle, or rather with the tunica albuginea, adheres so closely that it cannot be separated, except very partially and in shreds; but it may be detached easily from the epididymis, with the con- volutions of which it is in immediate contact. This sac is longer and larger than the testicle itself, from which cause it ascends for several lines above the superior end of the gland, and the free part hangs loosely about it. Its cavity may, with but little force, be injected so as to hold an ounce or two of fluid. This membrane is smooth and polished on the surface forming its cavity, and contains a small quantity of serous halitus, which allows the opposed surfaces to glide freely upon one another. Its exterior connexion with the dartos is so slight that it may be with- drawn without dissection, with the exception of an adhesion at the THE TESTICLES. 109 lower end of the testis arising from the remains of the guberna- culum : in such case, however, it still continues to be invested by the tunica vaginalis communis, from which it can only be removed by a special dissection. The Tunica Albuginea is the proper coat of the testicle, is in immediate contact with its glandular structure, and serves to main- tain its shape, as well as to protect it from pressure. From its internal surface proceed many membranous, horizontal fibres, which form partial partitions of its cavity (Septula Testis) and incline towards its posterior part, where they terminate in a longi- tudinal projection, called Corpus Highmorianum. The latter is of a prismatic shape, somewhat broader above than below, and is of but little consequence, except that it was once erroneously sup- posed to be a sinus, into which the seminiferous tubes discharged. Sir Astley Cooper proposes to call this the mediastinum testis, and considers the Corpus Highmorianum as being formed by an inflec- tion of the tunica albuginea. The Septulae Testis, he asserts, really envelop the seminiferous tubes, by forming bags which sup- port, confine, protect, and nourish the tubular structure of the testis.* The albuginea is perforated by several foramina along its posterior margin, where there is a deficiency of tunica vagi- nalis, for the passing of excretory ducts and blood vessels. This membrane is dense, strong, white, and fibrous, resembling in structure the tunica sclerotica of the eye, and the dura mater of the brain. Sir A. Cooper considers the tunica albuginea as consisting of two layers which can be readily separated by dissec- tion, excepting in front; the outer layer is the fibrous one, while the internal one, which he calls Tunica Vasculosa, has the sper- matic arteries and veins ramifying upon it. They are rendered very distinct from each other by a minute injection.f Of the Minute Structure of the Testicle.%—The glandular por- tion of the testicle consists in a congeries of zig-zag tubes (Tubuli Seminiferi) which are collected into lobules. One, two, or more tubes constitute a lobule, and the lobules are kept apart by the * Observations, &c. on the Testis, p. 14. London, 1830. t Id. t Hunter, Med. Comment, p. 1. 1777. Albinus, Acad. Annot. Lib. n. Loder, Tal». Anat. Ruysch, Thes. Anat. iv. Haller, Op. Min. torn. ii. Alex. Munro, de Testibus, Ed, 1755. 110 ORGANS OF GENERATION. septulae testis. These lobules are of a conoidal shape, having their points towards the posterior middle line of the Testis and their bases rounded, they diverge from the corpus Highmorianum, so as to fill up the cavity of the tunica albuginea. Their number is, according to Krause, from 404 to 484. The entire number of tubes amounts to 300, according to Dr. Munro; with an aggre- gate length of 5208 feet. The diameter of each one does not exceed one two-hundreth part of an inch, and its length is some- what short of seventeen and a-half feet. Lauth has stated the number of tubes to be 840, and the length of each to be about twenty-seven inches, which corresponds nearer with my own ob- servations, and makes an aggregate length of about one-third of that represented by Dr. Munro. These tubes form convolutions or hanks, the threads of which are serpentine, very much like the thread of a ravelled stocking; and are held together by a delicate cellular substance easily softened by maceration. Each tube forms of itself a hank, which is kept distinct from the adjacent ones by the septulae or processes of the albuginea, and may be easily picked out from them. Their extreme tenuity and delicacy of structure cause them, when well macerated, drawn out with a pin, and then suspended in water, to resemble a tangled skein of fine silk. The tubuli seminiferi finally terminate in some straight tubes, called the Vasa Recta, which unite near the middle back part of the testicle in a somewhat complicated arrangement, obtaining the name of the Rete Vasculosum Testis. This Rete Vasculosum is placed in the Corpus Highmorianum and from it there proceed from twelve to eighteen ducts (VasaEfferentia) which go upwards ' and backwards through the corpus Highmorianum and the tunica albuginea. Each of these vasa efferentia is then convoluted upon itself into a conical body, called Conus Vasculosus, which pre- sents its base backwards. Each conus, at its base, has its tube entering successively into the tube of which the Epididymus is formed. Notwithstanding the extreme tenuity of these several arrange- ments in the excretory ducts of the testicle, they may be entirely filled with quicksilver from the vas deferens; but the task is one of great difficulty, and rarely succeeds. The anterior ends of the tubuli seminiferi would seem from the THE TESTICLES. Ill observations of Lauth and Krause,* to have different modes of ter- minating, some end by cceca, others by a loop, and others by anas- tomosis with contiguous tubes. These anastomoses according to Lauth, are most frequent towards the base, and occur there about every three inches. At the other end the seminal tubes seem to be convoluted, several unite into one, to form a vas rectum, of which there are at least twenty, and with a diameter larger than the tubuli seminiferi. The vasa recta are a line or two long, they then are reduced into from seven to thirteen trunks, forming what is called the Rete Vascu- losum Testis, which is distinguished by the waving course of its trunks, and by their frequent anastomoses with each other. According to Lauth, the number of vasa efferentia varies from nine to thirty, and when the entire length of each one is extended it measures eight inches: of course, including the conus Vascu- losus. The average length of the canal of the Epididymis is about twenty-one feet, and the coni vasculi discharge into it at intervals of three inches and a quarter.f The Epididymis is the prismatic arch which rests vertically on the back of the testicle, and adheres to it by the reflection of the tunica vaginalis. It is enlarged at both ends, the upper of which, being formed by the Coni Vasculosi is called the Globus Major, and the lower enlargement is the Globus Minor. It is made of a single convoluted tube, of the fourth of a line in diameter. After this tube has got to the lower end of the globus minor it becomes less convoluted, enlarges, turns upwards on the inner side of the epididymis, and obtains the name of Vas Deferens, which before it reaches the top of the epididymis has become perfectly straight, or almost so. There is a blind duct, (Vasculum Aberrans) which begins at the top of the epididymis and terminates below; the base of it is up- wards, and the other end discharges into the lower end of the ca- nal of the epididymis, where the latter makes its turn into the vas deferens. Its length varies from one and a half to fourteen inches. Sometimes there are several. The use is unknown. The tubuli seminiferi form a system of closed tubes, with the ex- ception of the posterior end, which discharges into the Rete Testis. * Miiller, loc. cit. p. 499. t Lauth see Mailer. 112 ORGANS OF GENERATION. Their diameter being about fifteen times greater than that of the arteries ramifying upon them, the conclusion is drawn that their whole internal surface executes the seminiferous secretion. Of the Spermatic Chord. The spermatic Chord is a fasciculus of about half an inch in dia- meter, which may be felt very readily through the skin of the scro- tum, passing from the upper end of the testicle to the external ab- dominal ring. It is formed by the Vas Deferens; the Spermatic . Artery and Veins ; the Lymphatics of the Testicle; and the Nerves; all being covered in by the Tunica Vaginalis Communis, and by the Cremaster Muscle. The Cremaster Muscle, also called the tunica elythroides,* being derived from the internal oblique and the transverse muscle of the abdomen,f forms a very complete envelope to the chord from the abdominal ring to the testicle. But when it reaches the latter its fibres spread out and become indistinct upon the tunica vaginalis communis, as they there consist in small, pale, scattered fasciculi; many of which terminate insensibly, while others form on the front of the tunica vaginalis loops, having their convexities downwards. This muscle draws the testicle upwards, an action very different from the corrugation of the scrotum. The Vas Deferens, or the proper excretory duct of the testicle, is a white tube of about a line and a half in diameter, and has a cartilaginous feel. Its parietes are thick, as its cavity will not re- ceive a body larger than a bristle, without being put upon the stretch. It traverses a long space, and in doing so, first passes at the back of the chord from its commencement to the internal abdo- minal ring: having reached the latter, it then abandons the sper- matic artery and vein, and dipping into the pelvis, by the side of the bladder, goes between the lower fundus of the latter and the ureter. It then converges towards its fellow, along the under ex- tremity of the bladder, at the inner margin of the vesicula seminalis of the same side, and finally terminates in the urethra near the * Ewl^ot a sheath. f See Abdominal Muscles^ THE TESTICLES. 11 3 neck of the bladder, by forming the Ductus Ejaculatorius with the assistance of the duct of the adjoining vesicula seminalis. About two and a half inches from its termination, it enlarges and becomes somewhat tortuous. This duct consists of two coats: the external one is hard, com- pact, and occasionally, fibres are seen in it; but its structure is not very evident, and is peculiar. The internal is a mucous membrane. For the description of the remaining portions of the chord, see Spermatic Artery, Vein, Lymphatics, and Plexus of Nerves. The Testicles undergo a remarkable change in their position, from the earliest development of their rudiments to the perfect fce- tal state. They are not formed in the scrotum, but in the abdo- men just below the kidneys; from which position they are gradu- ally transferred. About the middle of the third month of gesta- tion they are two lines long, and placed behind the peritoneum, to which they loosely adhere. The vas deferens then, instead of rising up on the side of the epididymis, goes straight down into the pelvis. At this period may be seen the gubernaculum testis, discovered by J. Hunter,* which becomes more distinct in a few weeks after- wards, and assumes a triangular appearance. This gubernaculum has the office of drawing the testicle down into the scrotum ; its point commences in the upper part of the latter, somewhat below the external abdominal ring; it passes through the abdominal ca- nal, ascends upon the iliacus internus muscle, and is attached by its base to the inferior end of the testicle. In front of the guberna- culum, a process, or small pouch of peritoneum, passes through the abdominal canal to the upper part of the scrotum. By the con- traction of the gubernaculum, the testicle is brought, about the seventh or eighth month, into the scrotum, by sliding down behind the pouch. The lower end of the pouch, at which the testicle is finally arrested, becomes the tunica vaginalis testis. As soon as the testicle has reached the scrotum, the neck of the pouch has a tendency to close and to become obliterated, which is commonly accomplished at the period of birth ; yet it sometimes remains open for a longer time and becomes the occasion of con- genital hernia. Very generally at birth, the orifice of the pouch ^W * Med. Comment. Lond. 1777. Vol. II.—11 114 ORGANS OF GENERATION. will receive the end of a probe to the depth of a line or two; but all below is perfectly closed, and has its structure so condensed and altered, that no one, from a view of it alone, would suppose that the cavity of the tunica vaginalis had ever communicated with that of the peritoneum.* SECT. IV.—OF THE MUSCLES AND FASCLE OF THE PERINEUM. Perineal Fascia. The Perineal Fascia is placed just beneath the skin of the peri- neum, and covers the muscles. It is spread over nearly all the space between the anus and the posterior margin of the scrotum, and between the rami of the pubes and the ischia on each side: it is very firmly fixed to these bones, and is gradually blended with the cellular substance of the posterior part of the scrotum. This fascia is rather thin, but, in case of a rupture of the pos- terior part of the urethra, prevents the urine from showing itself in the perineum, and drives it into the cellular structure of the scrotum. In abscesses of the perineum, it also prevents the fluctuation from being very evident. The Musculus Erector Penis, It is so situated, as to cover the whole of the crus of the penis which is not in contact with the bony margin of the pelvis. It arises, therefore, tendinous and fleshy, from the anterior part of the tuber ischii; its fleshy fibres adhere to the internal and exter- nal margins of the ramus of the ischium, and of the pubes, and pro- ceed upwards: just before the union of the crura of the penis, they * The explanations and anatomy of this process have been treated at large in the following works: Girardi, Tabul. II. adj. Septemd. Tab. Santorini. J. Hunter, Observations on certain parts of the Animal CEconomy. W. Hunter, Med. Commentaries. ^^^ Edwardi Standifort, Opusc. Anat. ^^m Wrisberg. Comment, Medic. Physiolog., &c. MUSCLES AND FASCIA OF THE PERINEUM. 115 end in a flat tendon which is lost on the side of the corpus caver- nosum of the penis.* Its use is not well understood. The Musculus Accelerator Urina, Lies on the bulb and back part of the corpus spongiosum urethras: it is a thin muscle, consisting of oblique fibres. It arises by a pointed production from the side of the body of the penis; its origin is continued obliquely across the inferior sur- face of the crus penis, where the latter begins to form the body of the penis. It arises, also, for an inch from the inner side of the ramus of the pubes, between the crus penis and the triangular ligament of of the urethra. The muscles of the opposite sides are inserted into one another by a white line, which marks the middle of the bulb of the urethra; and by a point, into the anterior extremity of the sphincter ani, where they are joined by the transversi perinei. In order to see the origin of these muscles very distinctly, sepa- rate them from each other in the middle line, and dissect them from the corpus spongiosum. Cut transversely through the cor- pus spongiosum about three inches before the triangular ligament, and dissect it clearly from the corpus cavernosum, turning it down- wards so that it may hang by the membranous part of the urethra. By putting the two acceleratores on the stretch, it will be seen that besides the origins mentioned, they arise, also, from each other by a tendinous membrane that is interposed between the corpus spon- giosum and cavernosum ; so that they literally surround the back part of the urethra, constituting a complete sphincter muscle for it. This account of the accelerator urinas being peculiar to my- self, is adopted from a strong analogy between it and the sphincter vaginas. The two muscles are considered by M. Chaussier as forming but one: in that case its origin will be reversed, and commence in the middle line of the perineum instead of terminating there. As this muscle, and the erector penis, touch by their contiguous faces, it is difficult to get into the membranous part of the urethra in ♦The late Dr. Lawrence informed me that he had frequently found muscular fibres between the bone and the crus penis. 116 ORGANS OF GENERATION. lithotomy without cutting through the muscular fibres of one or the other. It propels the urine and semen forward. The Musculus Transversus Perinei, As its name implies, passes directly across the perineum; it arises from the inner side of the ischium, just at the origin of the erector penis, and is inserted where the sphincter ani and accele- rators urinae join. I have observed that when the lower part of the accelerator was extended much below its usual line, and strongly developed, that the transversus was very irregular in its origin and course; consisting frequently of a few fibres which did not deserve the name of a distinct muscle, and lying almost unappropriated in the adipose matter of the part, Occasionally, a fasciculus of muscular fibres exists, called, by Albinus, Transversus Perinei Alter, which arises in front of the transversus: it seems generally to be a loose fasciculus of the ac- celerator urinae muscle, and is inserted into the perineal junction just behind it. The use of these muscles seems to be to contribute to fix the bulb of the urethra. The Musculus Sphincter Ani, Consists in a plane an inch thick, of elliptical fibres immediately beneath the skin of the anus, and which surrounds the latter in order to keep it closed. The long diameter of the ellipsis is ex- tended from the coccyx towards the symphysis pubis, and has its angles very much elongated; the anterior may be traced termi- nating insensibly in the posterior face of the scrotum. It has two fixed points, the last bone of the os coccygis behind, the perineal union of the other muscles in front; its lateral diameter occupies about one-half of the space between the tuberosities of the ischia, and it is in the middle of this space. Besides closing the orifice of the rectum it will draw the bulb of the urethra backwards, or the point of the os coccygis "for- wards. MUSCLES AND FASCIA OF THE PERINEUM. 117 The Musculus Coccygeus, Belongs to the interior of the pelvis. It arises by a small, ten- dinous, and fleshy beginning, from the spine of the ischium, and, lying on the anterior face of the anterior sacro-sciatic ligament, it is inserted into the side of the last bone of the sacrum, and of all those of the os coccygis. It draws the os coccygis forwards. It frequently happens that there is on each side a small fasci- culus of muscle arising from the inferior bone of the sacrum in front, and inserted into the bones of the coccyx ; it is called Sacro- Coccygeus. A large quantity of adipose and cellular matter exists on the side of the rectum, between it and the parietes of the pelvis, concealing the perineal surface of the levatores ani muscles. The Musculus Levator Ani, Arises, fleshy, from the back of the pubes near its symphysis,. and from near the superior margin of the foramen thyroideum above the obturator internus muscle. It also arises from the apo- neurosis pelvica, where this membrane is extended as a thickened semi-lunar chord from the superior margin of the thyroid foramen towards the spinous process of the os ischium. This second part of the origin of the levator ani is defectively described in most books on anatomy. It is then seen to cross obliquely, as far as the spine of the ischium, that portion of the obturator internus which arises from the plane of the ischium. From this extensive origin the fibres converge and descend backwards, and have three distinct places of insertion; the pos- terior fibres are inserted into the last two bones of the os coccy- gis; the middle, and by far the greater number, are inserted into the semicircumference of the rectum between its longitudinal fibres and the circular fibres of the sphincter ani; and, finally, the most anterior fibres pass obliquely downwards and backwards on the side of the vesical end of the membranous part of the urethra, and on.the side of the prostate gland, and are inserted into the com- mon place of junction of the perineal muscles. 11* 118 ORGANS OF GENERATION. The fore part of this muscle is by some of the English anato- mists, as stated, called the Compressor Urethras.* The Triangular Ligament of the Urethra, Is a membrane which fills up the space below the symphysis of the pubes, and answers there as a septum between the perineum and the pelvis: when closely examined, it is seen to connect itself to the internal edges of the rami of the pubes and ischia on the inner posterior sides of the crura penis as far down as the begin- ning of the latter. At its lower edge its ligamentous character is not so well defined. On its anterior surface is the bulb of the urethra, and just at the extremity of the latter, enclosed by the ligament, and adhering to it, are Couper's Glands. In contact with it behind, and adhering, is the prostate gland, covered by its fibrous capsule, which is a continuation of the pelvic aponeurosis over it. A perforation exists in it, through which passes the membranous part of the urethra. This opening is not very ap- parent, in consequence of its edges being continued a little dis- tance on the canal; but by detaching them the whole becomes well defined. The relative situation of the bulb and of the membranous part of the urethra is such, that the former goes towards the anus, while the latter passes upwards towards the neck of the bladder; they, consequently, form a considerable angle with each other. The membranous part of the urethra is much the deepest, the re- collection of which is all-important in lithotomy, as it teaches us to avoid the one, and to cut into the other. It may also be ob- seved, that the hole in the triangular ligament is an inch below the symphysis pubis. By removing the upper corner of the triangular ligament, we are made acquainted with another just behind it, which is totally distinct. This ligament is half an inch broad, is thick and strong, particularly at its lower edge, and is very firmly attached laterally to each of the pubes, just below the symphysis: it is a continua- tion of the ligamentous union of the symphysis pubis. Mr. Colles calls it pubic ligament, with great propriety. I would suggest,. * Wilson's Anatomy, p. 198. * MUSCLES AND FASCIA OF THE PERINEUM. 119 as somewhat more expressive, the term Inter-Pubic Ligament ;* as it serves to distinguish it from another called Pubic, which is above the pubes, and described in the account of the recti abdo- minis muscles. The breadth of this having been stated at half an inch, it is obvious that the hole in the triangular ligament is half an inch below its lower edge. Pelvic Fascia. The Pelvic Fascia (Aponeurosis Pelvica) connects the bladder to the sides of the pelvis. " This fascia descends from the ileo- pectineal line to about midway in the depth of the pelvis; here it is reflected from the surface of the muscle, (the Levator Ani,) and applies itself to the prostate gland and bladder on the body of which it is ultimately lost. At the angle of its reflection, this fascia appears particularly strong and white, but becomes more weak and thin as it lines the muscle and covers the bladder. In tracing this membrane it will be seen that from the pubes just below the symphysis, a pointed production of it, constituting its anterior mar- gin, is fixed into the side of the neck of the bladder. This pointed production on each side is called, by most anatomists, the anterior ligaments of the bladder. Between them, just beneath the sym- physis of the pubes, a pouch large enough to receive the end of the finger, is formed by the union of the fascias of the two sides: this pouch connects the middle anterior part of the neck of the bladder to the lower margin of the symphysis pubis."f This fascia adheres closely to the periosteum of the pubes, be- tween the upper margin of the thyroid foramen and the crista of the pubes; about the middle third of the linea innominata it is ob- viously a continuous membrane with the iliac fascia which covers the iliacus internus muscle; but behind this, again, it arises from the remaining third of the linea'innominata. The portion of this fascia which Mr. Colles speaks of as parti- cularly strong and white, forms a bow, the concavity of "which looks upwards, one end of the bow being fastened to the pubes above the foramen thyroideum, and the other end to the ischium above its spine. The perineal surface of this bow is an important point of the origin of the levator ani. Above the bow this fascia * See Symphysis Pubis. t Colles'Surgical Anatomy. 120 FEMALE ORGANS OF GENERATION., is very thin, for the fibres of the obturator internus can be readily seen through it. At the bow the fascia divides into two laminae; one pursuing its course to the bladder and rectum, the other covers the lower part of the obturator internus muscle, and thereby constitutes the obtu- rator fascia. The levator ani is interposed between these two laminas. The aponeurosis pelvica also forms a bow or semi-lunar edge in front of the sacral nerves. The triangular ligament and this fascia are so identified in forming the capsule of the prostate, that the latter, in description, may be referred either to the one or the other, or to both, according to the fancy of the describer. CHAPTER II. Of the Organs of Generation in the Female. The Copulative Organs in the female are, the Vulva and the Vagina; the Generative are the Uterus and the Ovaria. SECT. I.—OF THE VULVA. The term Vulva is applied to the most superficial of the copula- tive organs, and consist in the Mons Veneris, the Labia Externa, the Labia Interna, the Clitoris, the Vestibulum, the Orificium Ure- thras, the Fourchette, and the Fossa Navicularis. The Mons Veneris is the protuberance on the fore part of the pubes. Its size varies considerably, according to the state of obesity of the subject, in consequence of its being formed by a de- posite of fat between the skin and the bone: in corpulent women it is very large and prominent, whereas, in such as are much ema- ciated, it simply describes the outline of the bones. The skin, there, is abundantly furnished with sebaceous glands, seated in the cellular texture beneath it, and about the size and shape of millet seed. At the age of puberty a growth of hair takes place upon it, which is not so long as the correspondent growth upon men, and THE vulva. 121 is not so much disposed to spread itself over the lower part of the abdomen as life advances. In women who have abused coition, it is said that these hairs become much curled. The Labia Externa are a continuation of the mons veneris down- wards in the form of an oblong eminence on either side. Their elevation is produced in the same way by a deposite of fat beneath the skin. They are somewhat broader and more prominent above than below. On the side which is next to the thigh, the integu- ment is common skin, sparingly covered with hair; but on the other face it is a mucous membrane, being a continuation of that of the vagina. The skin here, as well as at the commencement of every mucous membrane, is insensibly changed into the latter. They have many sebaceous glands externally, and mucous glands internally, upon them. Much cellular membrane, like that of the scrotum, is found in their interior structure; whereby they enjoy great extensibility in order to favour the dilatation of the parts in parturition. The rima which exists between them is the Fissura Vulvae of authors, and is about twice the length of the orifice of the vagina; this arrange- ment of it gives increased facility to the expulsion of the foetus. The Fourchette or Frenulum Vulvae, is situated at the posterior commissure of the labia externa, and is a thin, narrow transverse duplicature of skin; which, owing to its weakness, is most fre- quently ruptured at the first act of parturition, and then dis- appears. The Clitoris bears, in some respects, a resemblance to the penis of the male, but is by no means so large. It is situated imme- diately below the symphysis pubis, and consists in a cylindrical body of three or four lines in diameter, with two crura. The body is an inch long; the crura are likewise of the same length, and arising from the internal face of the crura of the pubes, unite be- neath the symphysis so as to form the body. The body is not straight, but has the anterior half bent downwards and forwards. The exterior covering, or capsule of the clitoris, in its texture, resembles the elastic ligamentous membrane of the corpus caver- nosum penis; and is, moreover, filled within by a similar cavernous or cellular structure, which is divided into two equal parts by a septum pectiniforme, and is susceptible of distention during sexual 122 FEMALE ORGANS OF GENERATION. excitement. The clitoris is supplied also with blood vessels and nerves like the penis, and is held up to the under part of the sym- physis pubis by a suspensory ligament. The anterior extremity of the body of the clitoris is found in the rima or fissura vulvas, about an inch below the upper commissure of the labia externa. It projects somewhat, and bears a general resemblance in shape with the end of the penis, whence its name of glans clitoridis; but it has not the same organization, excepting the delicacy, the extreme sensibility, and the vascularity of the skin which covers it. The clitoris has no corpus spongiosum, neither is it concerned, like the penis, in conveying the urine from the bladder. Its glans is covered by a doubling of skin called the prepuce, and is likewise furnished with the glandulas Tysoni, from which is discharged a smegna, or sebaceous fluid, as in the male. The prepuce does not furnish a regular well defined frasnum. The Erector Clitoridis muscle corresponds with the erector penis. It arises from the ascending ramus of the ischium, and, covering the inferior face of the crus clitoridis, runs as far for- wards as the commencement of the body. The Labia Interna, or Nymphae, are two duplicatures of the mucous membrane of the vulva, which pass down, one on each side, from the clitoris. The prepuce of the latter terminates, on either side, in the labia; while the latter are continued upwards, by a narrow process, to the under surface of the glans clitoridis. They arise all along their base, from the internal sides of the labia externa, or majora; and being wider in the middle than elsewhere, they terminate insensibly about half-way down the orifice of the vagina. Between the laminae of each one is placed a vascular cellular substance, susceptible of distention and of partial erection during sexual excitement. In young subjects, their vascularity communicates a vermilion tinge, which is lost and becomes brown- ish in the progress of life. As they are effaced during parturition, their chief use seems to be as a provision for the great distention of the vulva, which then occurs. The labia interna are about half an inch broad in the natural state, and do not project obviously beyond the labia externa, ex- cept in cases of extreme emaciation, where the prominence of the latter has been destroyed by a removal of its fat. They are, how- ever, very subject, as the individual becomes old, to a pointed THE VULVA. 123 elongation, increasing their breadth to an inch, or an inch and a half; and to become thickened and indurated. A tribe of Hotten- tots, the Boschismans, living near the Cape of Good Hope, are uniformly subject to this enlargement; which, for a long time, was represented, by travellers, as an organ superadded to what is com- mon in the human species. The Vestibulum is a depression of twelve or fifteen lines long between the labia interna ; it is bounded above by the clitoris, and below by the orifice of the vagina. It is abundantly furnished with mucous lacunas. The Urethra of the female has its external orifice (Orificium Urethra) in the inferior part of the vestibulum, about one inch below the glans clitoridis, and is generally marked by a slight rising, which is easily distinguished by the sensation of touch alone; its margin is often bounded by a little caruncle on each side.* The urethra itself is an inch long, larger and much more dilatable than that of the male, its course is obliquely downwards and forwards from the neck of the bladder; passing under the symphysis of the pubes, and being slightly curved from that cause. It consists of two membranes, a lining and an external one. The lining membrane is a continuation of that of the bladder; it is thrown into several longitudinal folds, and has many mucous folli- cles in it. The external coat of the urethra consists of condensed laminated cellular membrane, having a strong affinity with mus- cular fibre: the principal direction of the fibres is transverse, form- ing a cylindrical body of half an inch in its transverse diameter, and which has given the idea of the existence of a prostate gland in the female: the lower and lateral surfaces of this cylinder are in contact with the vagina, forming a protuberance into its cavity; and the upper surface is firmly connected to the triangular liga- ment of the pubes. Immediately behind the neck of the bladder, we find the vesical triangle with its muscle, as in the male, except- ing that the anterior angle of it goes to the anterior end of the urethra. * Doctor Pancoast considers the urethra of the young female to have its orifice on a level with the anterior face of the Symph. Pubis, whereas, in such as have borne many children it is behind the pubes. Wistar's Anat. vol. ii. p. 182. Phil. 1839. 124 FEMALE ORGANS OF GENERATION. The Fossa Navicularis is that portion of the rima vulvas which is below the vestibulum, and anterior to the orifice of the vagina. SECT. II.—OF THE VAGINA. The Vagina is a thin membranous canal which leads from the vulva to the uterus. It is from four to six inches in length, differ- ing according to age and pregnancy, and being much shorter in women who have borne children than in virgins. It is placed be- tween the bladder in front, and the rectum behind, being flattened by them so as to bring its anterior and posterior surfaces into con- tact. Its anterior extremity is the smallest of the two; and pre- sents its greatest diameter vertically, while that of the posterior is transverse. As it follows accurately the central line of the pelvis, it is, consequently, curved with its concavity forwards. Its ante- rior parietes are shorter than the posterior, both from the smaller depth of the pelvis in this direction, and from the mode of con- nexion with the uterus. The vagina is formed by two tunics; a fibrous and a mucous one. The first is external, of a light red colour, highly elastic, and seems to consist of condensed cellular membrane, the fibres of which are much intermixed, and pass in every direction. It is vascular, and immediately adjacent to the large venous sinuses of the pelvis. The mucous membrane being a continuation of that of the vulva, is at and near its anterior orifice of a vermilion tinge; while, posteriorly, it is grayish and frequently spotted, so as to give it a marbled appearance: its thickness diminishes as it recedes from the external orifice; and upon being floated in water many mucous lacunae are observable upon it. The internal surface of the vagina is commonly covered with the mucus which comes from its lacunas. On the anterior or pubic portion, it is divided longitudinally by a middle ridge, which commences by a sort of tubercle just below the orifice of the urethra, and proceeds backwards, becoming indistinct as it ap- proaches the uterus. Transverse ridges formed in the same way by folds of the mucous membrane, arise from the sides of the last at its anterior portion, and give a roughness to that part of the va- gina. The inferior side, or that next to the rectum, has the same kind of arrangement of the mucous membrane, but not so distinct. THE VAGINA. 125 In a majority of subjects, the uterine half of the vagina is perfectly smooth, but the rule does not always hold. The Corpus Spongiosum Vaginas is an erectile tissue, like that of the penis, and closely resembles in structure the corpus spongio- sum urethras. It is placed at the anterior end of the vagina, on its outer circumference, just below the clitoris, and at the base of the labia minora or interna. It is an inch broad, and a line or two thick, adheres closely to the fibrous coat of the vagina, and extends around the superior semicircumference of the orifice, but not around the anterior. It is frequently called Plexus Reti- formis. The Sphincter Vaginas Muscle surrounds the anterior orifice of the vagina, and covers the plexus retiformis. It is about an inch and a quarter wide, and arising from the body of the clitoris and the crus of the pubis, behind the crus of the clitoris, passes back- wards and downwards to be inserted into the dense, white sub- stance, in the centre of the perineum, common to these muscles, the transversi perinei and the anterior point of the sphincter ani. There is a strong analogy between it and the accelerator urinae of the male. The Transversus Perinei of the female, has the same circum- stances of origin and insertion as in the male, but is not quite so strong. On each side of the orifice of the vagina, near it? middle, is fre- quently found a mucous gland, the size of a garden pea: it corre- sponds with Cowper's gland of the male subject. The Hymen,* one of the attributes of the virgin state, is placed at the anterior orifice of the vagina for the purpose of closing it, and commonly remains until it is ruptured by violence. In all cases, except where there is an unnatural adhesion, it leaves a small orifice for the passage of mucus and of menstrual blood. In my own observations, I have found it most frequently crescentic, the convexity of the crescent presenting downwards, and the horns * J. G. Tolber, Diss, de Variet. Hymen. Haller, Icon. Anat. Fasc. i. Albin. Acad. Annot. Lib. iv. Santorini, Septemd. Tab. Vol. II.—12 126 FEMALE ORGANS OF GENERATION. upwards; but in some cases it is to one side. Next in frequency to the lunated is the circular shape, where it surrounds completely the orifice and leaves a hole in its own centre. There are some other varieties, such as its being fleshy, fasciculated, unequally di- vided into two portions, and so on, which are narrated by diffe- rent writers. Being simply a duplicature of the mucous membrane, it is generally so weak as to be ruptured at the first act of copu- lation, or even from slighter causes during infancy: but occasion- ally, it becomes thickened, and so strong as to require division with the knife. After the rupture of the hymen, its place is indi- cated in subsequent life by from two to six small tubercles, called Carunculas Myrtiformes, which are its remains. The peritoneum, in descending from the uterus, anteriorly, touches the top of the vagina for a little distance, and is then re- flected to the bladder, but posteriorly, almost the upper half of the vagina has a peritonea] coat before this membrane is reflected to the rectum. The attachment of the vagina to the bladder is strong and close just above the urethra, but its connexion with the rectum is by rather loose cellular substance. SECT. III.—OF THE UTERUS, AND ITS APPENDAGES. The Uterus, or Womb, is a compressed pyriform body, the larger end of which stands upwards, while the lower is directed downwards, and is attached to the vagina.* Unimpregnated, it is two and a half inches long, and one and a half in diameter at its widest part. The posterior face is very convex, while the ante- * This is commonly represented by anatomists in their plates and descriptions as the position of the womb; it is, however, more so in advanced pregnancy than when empty. In my dissections generally, I have found the posterior face of the womb downwards, reposing upon the concavity of the rectum, and the ostincae obliquely forwards; this position being probably produced by thesuperincumbenceof the small intestines, and, especially, when the bladder is empty. When the latter is full, the peritoneum is reflected from the centre of the uterus to the posterior face of the bladder, and its traction has the effect of erecting the uterus in part, from its nearly horizontal direction. In a dissection of a female, April 9,1838, aged eighteen, who died from an affection of the brain, there being every evidence of soundness in the genital organs, I found the rectum making a curve to the right side of the infe- rior part of the sacrum, and the body of the womb, reposing in the concavity of the latter. UTERUS, AND ITS APPENDAGES. 127 rior is almost flat, or very slightly convex. It is about one inch in thickness. It is divided by anatomists into fundus, body, and neck. The fundus is formed by its superior extremity, and com- prises the space between the orifices of the Fallopian tubes: the neck is the lower cylindrical portion, of about an inch in length; and the body is the part intermediate to the two. On the exterior circumference of the uterus, there are no marks or lines distinguish- ing these several portions, from each other. The uterus, being destined to lodge the foetus from a short pe- riod after conception to the moment of birth, has a cavity ready for its reception. The shape of this cavity bears some general, but not a rigid resemblance to that of the organ itself, and it is so much flattened as to have its anterior and posterior parietes in con- tact, or nearly so. The cavity of the body is an equilateral trian- gle of eight or ten lines in diameter; the sides of the triangle are bent inwards in parabolic curves, in such a way as to present their convexities to the cavity of the uterus : this of course, occasions an apparent elongation of the angles. The inferior angle is continued into the cavity of the neck, while the two superior run into their respective Fallopian tubes. From this arrangement it happens that the parietes of the uterus are only three lines thick on the angles of the triangular cavity, while at the middle they are from four to six lines. The cavity of the neck has not its anterior and poste- rior sides so near together as those of the body; and is rather cy- lindrical, being smaller, however, at the upper and lower ends than in the middle. This arrangement gives to its sides a paraboloid curvature which presents its convexity outwards, differing in that respect from the corresponding curvature in the cavity of the body. The cavity of the neck terminates in the vagina by an orifice about the size of a small writing-quill, but ovoidal, and presenting its long diameter transversely. This orifice is the Os Tineas, or Orificium Externum Uteri; frequently, without apparent disease, I have seen it conoidal, with its base, half an inch in diameter, pre- senting downwards. The upper orifice, whereby the cavity of th e neck communicates with that of the body is not subject to such fluctuations in size: it is occasionally called Orificium Internum Uteri, and is generally somewhat larger than a small writing-quill. The os tineas is bounded before and behind by the lips of the uterus, formed by the projection of the neck into the vagina. For the 128 FEMALE ORGANS OF GENERATION. most part the anterior lip is directly continuous with the anterior side of the vagina; so that its projection is very inconsiderable, and, indeed, not appreciable to the finger: at the same time, this lip is rather thicker than the posterior. The projection of the latter, on the contrary, is always well marked, because the vagina, in- stead of being inserted into its ridge, is joined to the posterior sur- face of its base. The cavity of the uterus is lined by a very thin mucous mem- brane, a continuation of that of the vagina. This membrane is of a light pink colour, which changes to a vermilion during the pe- riod of menstruation; it is said to be furnished with villosities, which, though seen with difficulty in the usual way, may be ren- dered apparent, by floating the uterus in water; and it adheres so closely to the substance of the uterus, that it forms an inseparable portion of it, which can neither be dissected nor macerated off en- tirely, as in the case of other mucous membranes. This membrane is smoothly laid upon the cavity of the body, and gives it a polished shining surface. On the cavity of the neck, it is wrinkled along the anterior and the posterior parts; there being a longitudinal line running along the centre, and on each side of this line transverse or oblique elevations or duplicatures. This ar- rangement presents an arborescent appearance, technically called the arbor vitas. In the interstices of these duplicatures there are some small mucous glands or lacunas, which as their orifices are exposed to obliteration from inflammation or some other irritation, become distended into small spherical sacs by the accumulation of their habitual secretion. Naboth, from seeing them in this state, mistook them for eggs, or the rudiments of the foetus, and the error has been commemorated by their being called Ovula Na- bothi. The uterus is covered completely by the peritoneum; in the re- flection of the latter, from the rectum to the bladder, it adheres to the uterus by a subjacent cellular substance, which allows it to be dissected off without difficulty. The same duplicature of perito- neum which encloses the uterus, is also reflected from each of its lateral margins, by their whole length to the corresponding side of the lesser pelvis, and forms the Lateral or the Broad Ligament, (Ligamenta Later alia, Lata.) The peritoneum in passing from the uterus forwards to the bladder, forms on each side, a duplica - UTERUS, AND ITS APPENDAGES. 129 ture, not very distinct, and depending, in a measure, upon the state of the bladder ; this constitutes the Anterior Ligament. The same membrane in passing from the back of the uterus to the rectum, and in covering the posterior superior end of the vagina, also forms, on each side, a duplicature, denominated the Posterior Ligament; they are always better seen than the anterior. Muscular fibres are said to be found, occasionally, between the laminae of these several duplicatures, running in the direction of the latter;* they have not been presented to me in such a way as to arrest my at- tention. The broad ligaments, along with the uterus, form a transverse septum, passing from one side of the pelvis to the other; and con- tain, between their laminas, the arteries and the veins which be- long to the uterus and ovaries. Besides the duplicatures of peritoneum, the uterus is retained in its position by the Ligamenta Rotunda, one on each side. These round ligaments arise from the sides of the uterus, a little below the insertion of the Fallopian Tubes, and going between the laminae of the broad ligament, reach, finally, the internal abdo- minal ring: they then traverse the abdominal canal and the ex- ternal ring after the manner precisely of the spermatic chord, and terminate by several fasciculi in the fatty cellular matter of the mons veneris and of the labia majora. The round ligaments are rather smaller in the middle than at either extremity; they consist of a condensed cellular or fibrous structure, and have many blood vessels in them. It has been asserted,! tnat tney contain strongly marked muscular fibres; some of which come from the uterus, and others from the broad muscles of the abdomen. No evidence of this fact has as yet been presented to me, though I do not deny it; and, indeed, I think it probable, that such fibres may be deve- loped there during gestation. The texture of the uterus is very compact, and of a cartilagi- nous feel; it is composed of fibrous matter, intermixed with a great many blood vessels. In regard to its fibrous structure, there is no subject in anatomy on which opinions are more divided, or more authoritative and numerous on both sides of the question. Some deny its existence at any period, while others admit it as a con- » J. F. Meckel, vol. ii. p. 605. t J. F. Meckel, loc. cit. 12* 130 FEMALE ORGANS OF GENERATION. stant condition: others, again, limit its duration only to the period of pregnancy. Without dwelling on the value of the several doc- trines, and the means and observations tending to support them, it may be sufficient here to mention that the structure of the uterus takes on very important and strongly marked changes, in passing from the unimpregnated state to that of advanced gestation. In the first the fibres look ligamentous and pass in every direction, but so as to permit the uterus to be lacerated more readily from the circumference to the centre than in any other course: it, in- deed, manifests an indisposition to be torn in a laminated manner. The fibres, moreover, break off short, are separated by the blood vessels, and seem to contain, in their interstices, something like fibrine. In the impregnated state, on the contrary, the vessels become immensely increased in size, the laminated structure becomes very evident, and submits readily to the tearing of one layer from the other: these lamina consist of fibres, which are principally paral- lel with each other. The muscular nature of these fibres seems to be sufficiently proved, by their powerful contraction in the expul- sion of the foetus, and on being irritated by the introduction of the hand. They are, however, not red like other muscles, but of a very light colour as those of the bladder and intestines ; and are collected into fasciculi of peculiar flatness and looseness. The development of this muscular structure is not, however, limited to the pregnant state, but it is disposed to manifest itself on all occa- sions which produce an increased size in the uterus. This fact was first exemplified to me in a small scirrhus of a virgin uterus, presented by Dr. Hugh L. Hodge,* and has been still farther con- firmed in a case, where the scirrhus was five or six inches in dia- meter ; also in a virgin uterus, very much enlarged from scirrhus, presented by Professor Charles D. Meigs.* A similar fact has been noticed by Lobstein,of Strasburg, where the tumour was also stea- tomatous. The fibres of the uterus, examined near the term of pregnancy, consist in two planes separated by the large blood vessels ; ons within and the other without. These layers are readily divisible into subordinate laminae, intermixed with one another but yet to a * Now Professor of Obstetrics in the University of Pennsylvania. t Of the Jefferson Med. College. UTERUS, AND ITS APPENDAGES. 131 considerable extent separable. The external layer is thicker than the interna], and both have an increased thickness at the fundus: while they are much diminished, and indeed indistinct, at the cervix. The fibres generally are either circular or longitudinal, but many of them are oblique. The exterior surface of the external plane, is composed principally of longitudinal fibres, within which are the circular. The inner plane, on the contrary, has the circular fibres external, and the longitudinal internal. In both planes the circular fibres are more abundant at the fundus, and the longitu- dinal upon the body of the uterus; but, generally speaking, there are collectively more longitudinal than circular fibres. Of the Fallopian Tubes. The Fallopian tubes (Tuba Fallopiana) are two membranous canals, one on either side, fixed in the superior margin of the broad ligaments of the uterus. They serve to conduct the rudi- ments of the embryo from the ovarium into the uterus. They are about four inches long, and extend from the upper angle of the uterine cavity to the side of the pelvis: their outer extremity is loose, and hangs upon the posterior face of the broad ligament over the ovarium, consequently inclines downwards, thereby forming an angle with the other portion. At their uterine extremities the Fallopian tubes are about the size of the vas deferens, resemble it strongly, and scarcely admit a hog's bristle; but having proceeded about one-half of their length, they begin to enlarge, and continue to do so rapidly for an inch, until they reach the size of a writing-quill; they then contract again somewhat, and immediately afterwards expand into a broad trumpet-shaped mouth. The latter has an oblique orifice, the edge of which is extremely irregular, by being resolved into a number of ragged fringe-like processes, of unequal size and length ; and which, as a whole, are called Corpus Fimbriatum, or Morsus Diaboli. One of the longest of these processes adheres to the ex- ternal end of the ovarium. The Fallopian tube is covered by the peritoneum, and consists of two coats: the external is fibrous, and bears sufficient resem- blance to the structure of the uterus to be considered a continua- 132 FEMALE ORGANS OF GENERATION. tion of it; the interna] is mucous, and is likewise a continuation of the corresponding one of the uterus. The external end of the tube, which is called Pavilion by the French anatomists, is flaccid, thin, and generally in a collapsed state, as it is formed solely by the mucous membrane, assisted by the peritoneum, neither of which furnishes resistance sufficient to keep it expanded; but, as many blood vessels enter into its composition, their turgescence, in sexual excitement, probably communicates a certain degree of erection. Mr. Grainger has ascertained that the Fallopian tube presents a difference in the structure of its mucous membrane, the part next the uterus, not being so vascular as the other part: moreover, the latter presents a complex arrangement in the form of folds or valves running in a longitudinal direction and plaited. We are left to infer that the difference is more conspicuous shortly after conception* There is some similitude in this arrangement with the oviducts of birds, one part of which secretes the albumen of the egg, and another part the shell, and it may be in the human subject, also, that the two parts execute different offices in the per- fection of the ovum. Of the Ovaries. The Ovaries, (Ovaria, Testes Muliebres,) two in number, one on either side, are situated on the posterior face of the broad liga- ments by a duplicature of which they are surrounded, and are twelve or fifteen lines below the Fallopian tubes. Their shape is that of a compressed ovoid, about half the size of the male testicle: their long diameter is horizontal; they are suspended from the broad ligament rather by the edge than by the flat surface, so that they project, and are to a considerable degree pendulous. Their distance from the uterus varies from an inch to an inch and a-half, and from the internal end of each one there proceeds a small vascular fibrous chord, the Ligament of the Ovarium, which is inserted into the uterus, somewhat below the origin of the Fallo- pian tube. From their being the seat of conception, they have, in the youth- ful and healthy female, a pliancy and succulency, indicative of * Mttller's Physiol., p. 1563. THE OVARIES. 133 their state of preparation for the act;.but in advanced life they diminish much in volume and become hard and dry. Their sur- face, originally smooth or slightly embossed, is subsequently ren- dered uneven, by repeated acts of conception, leaving on it a number of cicatrices or small stellated fissures. They are of a light pink colour. Within the peritoneal coat is another, the Tunica Albuginea, of a strong, compact, fibrous tex- ture, like the same coat of the testicle, and sending inwards many processes. The structure of the ovarium is as follows: But few females, of those presented in our dissecting rooms, have the part in a state fit for study, owing to age, disease, or excessive sexual in- dulgence: my best opportunities have been derived from post mor- tem examinations, in private, of individuals of from fourteen to twenty, where the virgin state had been preserved. When an ovarium of the latter kind can be got, by cutting through the tunica albuginea simply, and then tearing open the organ, it will be found to consist of a spongy fibrous tissue, abundantly furnished with blood vessels from the spermatic artery and vein. In this spongy tissue, called Stroma, are from fifteen to twenty spherical vesicles, (Ovula Graafiana,) according to the commonly received opinion; but in an ovarium exhibited to me by the late Dr. John Hopkinson, there were thirty-six distinct vesicles. They vary in size from half a line to three lines in diameter; the larger ones are nearer the surface, and, from having caused the absorption of the tunica albuginea, may sometimes be seen through the pe- ritoneal coat, and give to the surface of the ovarium an embossed condition. The vesicles contain a transparent fluid having within it the rudiments of the embryo. As the vesicles are evolved they advance from the centre to the circumference. Their pa- rietes are thin, transparent, and have creeping through them minute arterial and venous ramifications. The bed of the ovarium in which a vesicle reposes is called the calyx. The Ovula Graafiana seldom project much on the surface of the ovarium in the human subject; but in other animals, as the common hen, they, upon being developed, stand out so much as to resemble a cluster of berries each attached by its pedicle, and sur- rounded by its two appropriate sacs. These sacs constitute what are called the capsule of the ovum or the ovisac. Upon the inner 134 FEMALE ORGANS OF GENERATION. surface of this capsule, according to the observation of Schwann, is to be found a layer of epithelial cells in the different classes of animals, as, for example, in the ovicapsules of fish, and in the graafian vesicles or ovules of mammalia. The existence of these epithelial cells is considered as proof positive of the sameness of the membrane in whatever animals it may be examined; and, therefore, that the ovicapsules of oviparous animals are identical with the graafian vesicles or ovula of mammalia. The stages of development in an egg are, therefore, simply the expression of what occurs also in a graafian vesicle. Within the ovicapsule of birds is the yolk (vitellus) surrounded by its membrane called vitelline, which being at first in contact with the capsule, is afterwards separated from it in many animals by a well marked and large interval. The yolk is formed of fine cells containing granules and oil globules. In the substance of the yolk is the vesicle of Purkinje, or germi- native vesicle. This vesicle contains a transparent fluid, and has on it a nucleus, called the macula germinativa. This vesicle in the fully formed ova of the oviparous vertebrata is imbedded in a disk-shaped layer of granular substance, called the germ disk. The germinal vesicle is finally lost by commingling with the granular matter of the germ disk, in which the first rudiments of the embryo are formed. Upon the ovum leaving the ovarium in a bird it has to pass through the oviduct, and in doing so receives as a deposite upon it the white or albumen, and subsequently the shell which is also due to the secretory action of the oviduct.* To Von Baerf belongs the merit of discerning first the ovulum of man and mammalia in the graafian vesicle. The ovulum occu- pies but a very small part of the cavity of the graafian vesicle, the remainder being filled with an albuminous fluid in which micro- scopic granules float. By discharging the fluid from a graafian vesicle, the ovulum can with a simple lens be detected in a globu- lar form and floating in this fluid. By flattening out this little globe under a thin plate of glass, and then examining with a com- pound microscope, it will be seen that the ovulum consists of a * A satisfactory explanation of the above process, according to Wagner and others, is found in Muller's Physiol., p. 1468. London, 1842. t Mailer, p. 1469. THE OVARIES. 135 i transparent membrane containing a vitellus or yolk made of gra- nules or cells and fat globules. Within the above vitelline membrane is placed the germinal vesicle of the human subject,* being about -^ of a line in diameter. This vesicle has also the germinative spot, macula germinativa of Wagner, which is from the ^ close upon the left BRANCHES FROM THE ARCH OF THE AORTA. 221 border of the innominata; frequently, indeed, from a part of it. The left subclavian, though at its origin near the left carotid, gene- rally leaves a distinct interval of one, two, or three lines. The relative situation of these trunks is particularly alluded to in the account of the superior mediastinum. The last two are, of course, longer than the corresponding trunks of the right side, by the whole length of the arteria innominata. With the exceptions con- nected with their mode of origin, the arterial trunks of the two sides are exactly alike, and have the same mode of distribution. The Common Carotid Artery (Carotis Primiliva) being a branch of the innominata on the right side, and of the aorta on the left, goes up the neck to terminate just below the cornu of the os hyoides. In the early part of its course, the right one is more in- clined outwardly than the left, owing to its origin from the arteria innominata in front of, and to the right side of the trachea; where- as, the left ascends almost vertically. At the lower part of the neck, just above the sternum and the clavicle, the carotid is covered by the sterno-hyoid and thyroid muscles, and by the sternal portion of the sterno-cleido-mastoid. It is crossed obliquely on a line with the lower part of the thyroid cartilage of the larynx, by the omo-hyoid muscle. It lies at the side of the thyroid gland, the trachea, the larynx, the oesophagus, and pharynx, in front of the transverse processes of the cervical vertebrae, and the longus colli muscle; having on its outer margin, but somewhat in front, the internal jugular vein, and the pneumo- gastric nerve enclosed in the same sheath, and the sympathetic nerve behind. At the side of the larynx, the carotid is very super- ficial, and, with the exception of being crossed by the omo-hyoi- deus muscle, it is only covered by the platysma myodes and the integuments. The Carotid having got as high as the space between the os hyoides and the thyroid cartilage, but varying slightly in different subjects, there divides into two large trunks, the Internal Carotid, which goes to the brain and to the eye: and the External Carotid, which is principally distributed upon the more superficial parts of the head and neck. The first of these trunks is placed behind the other, and bends outwardly at its root: it is generally the largest in infancy, on account of the proportionate volume of the brain at that age; it is also swollen at its root, so as to form a sinus there, Vol. II.—20 222 CIRCULATORY SYSTEM. resembling an incipient aneurism. No branch, except in the ab- normous cases, is given off from the common carotid between its origin and bifurcation. SECT. II.—OF THE CAROTIDS, AND THEIR BRANCHES. The Internal Carotid, (Arteria Carotis Interna,) in the adult, is smaller than the external, and extends from the larynx to the sella turcica. It ascends between the external carotid and the vertebrae of the neck, being in front of the internal jugular vein, and having the pneumogastric nerve at its outer margin: as it gets on a level with the base of the lower jaw, it is crossed externally by the digastric and the stylo-hyoid muscles: it is immediately afterwards concealed in the subsequent part of its ascent by the ramus of the lower jaw. Having gone along the most internal or deeply seated margin of the parotid gland and the styloid process of the tem- poral bone, at the side of the superior constrictor of the pharynx, it then penetrates into the cranium through the carotid canal of the temporal bone. It is slightly flexed between its origin and the carotid canal: just before it reaches the latter, it curves upwards and forwards. The first part of its course through the canal is vertical, after- wards it goes horizontally forwards; and to escape from the canal it has once more to ascend almost vertically, which brings it to the posterior extremity of the Sella Turcica. On the side of the Sella Turcica it again passes horizontally forwards through the cavernous sinus; and at the anterior clinoid process it once more ascends, and, having penetrated the dura mater, it reaches the brain. In this passage, through the carotid canal, it is attended by the upper extremity of the sympathetic nerve, and gives one or more small branches to the petrous bone; it also gives a few branches to the dura mater and to the nerves about the cavernous sinus. But, for the full exposition of the distribution of the internal caro- tid, see the arteries of the Brain and of the Eye. The External Carotid Artery (Carotis Externa) extends from the termination of the primitive carotid, to the neck of the lower jaw. In the early part of its course, where it is situated in front CAROTIDS, AND THEIR BRANCHES. 223 of the internal carotid, and between the pharynx and the sterno- mastoid muscle, it is comparatively superficial, being only enve- loped by its sheath, and covered by the platysma myodes and the skin. Just above this place it is crossed externally by the hypo- glossal nerve, which detaches the descending branch along the front of its sheath and of that of the primitive carotid. Somewhat above this nerve, it is also crossed externally by the digastric and the stylo-hyoid muscle, and lies there on the side of the superior constrictor muscle of the pharynx, near the tonsil gland. About its middle, it is crossed internally by the stylo-glossus and the stylo-pharyngeus muscle; it then ascends through the substance of the parotid gland, between the ramus of the lower jaw and the ear, to its termination. Several very important branches are given off from the external carotid; they are as follow : The Superior Thyroid Artery (Art. Thyroidea Superior) arises from the external carotid, about a line above its root, and is dis- tributed to the larynx and to the thyroid gland. It goes at first inwards and forwards on the side of the larynx, being covered by the omo-hyoideus muscle, and by the platysma myodes; it then descends under the sterno-thyroideus to the upper margin of the lobe of the thyroid gland. In this course it performs several flex- uosities, of considerable variety in different individuals. The Laryngeal Branch comes from it near the superior margin of the thyroid cartilage; this branch glides in between the thyreo- hyoid muscle and the middle thyreo-hyoid membrane or ligament; after a short course, it penetrates the latter, and is then distributed in a great number of small twigs to the muscles and to the lining membrane of the larynx. A small trunk, either from the laryn- geal branch, or from the thyroid artery itself, is spent upon the crico-thyroid muscle, and traversing the front surface of the mid- dle crico-thyroid ligament, anastomoses with its fellow: small twigs from this branch penetrate to the interior of the larynx through the middle crico-thyroid ligament. Sometimes this crico- thyroid ramus is superior in size to the one above, in which case it principally supplies the interior of the larynx. The Thyroid Branch is the continuation of the principal trunk; rt penetrates into the substance of the thyroid gland, and divides into two ramuscles, one of which goes along the posterior face of 224 CIRCULATORY SYSTEM. the lobe of the gland, and anastomoses with the inferior thyroid; the other goes along the upper margin of the gland, and anasto- moses with its congener of the opposite side. The thyroidal artery is split up into a great many branches in the substance of the gland, it also sends small branches to the pharynx, oesophagus, and the little muscles on the front of the neck. The Lingual Artery (Art. Lingualis) comes from the external carotid at the distance of from six to twelve lines above the supe- rior thyroid, and goes to the tongue. It is concealed in the early part of its course by the digastric and the stylo-hyoid muscles; it then penetrates the hyo-glossus muscle just above the cornu of the os hyoides, or goes between it and the middle constrictor of the pharynx; it then ascends between the hyo-glossus and the genio- hyo-glossus muscle; advancing forwards, it is placed between the latter and the sublingual gland, and, finally, reaches the tip of the tongue. The lingual artery sends off the following branches. At the root of the tongue one or more trunks arise from it (Dorsales Lingua) which go to the base of this organ, the tonsils, the palate, and the epiglottis; one of these branches is called the inferior palatine. A little farther on, this artery detaches another branch, (Ramus Sublingualis,) which, advancing between the mylo-hyoid and the genio-hyo-glossus muscle, and above the sublingual gland, detaches a great many ramifications to these parts and to the lining membrane of the mouth; it is sometimes a branch of the facial. The Ramus Raninus, is the continuation of the lingual; it advances between the lingualis and the genio-hyo-glossus muscle, to the tip of the tongue, distributing continually its twigs on each margin, and ends there by anastomosing with the corresponding artery of the other side. The Facial Artery (Arteria Facialis, Maxillaris Externa) arises from the external carotid two or three lines above the lingual, and is spent principally on the side of the face below the eye. It is of considerable size, and very tortuous; its root is concealed by the stylo-hyoid and the digastric muscle, and it is traversed externally by the hypo-glossal nerve. It goes forward within the angle of the lower jaw, and above the submaxillary gland, but very much connected with it: it then mounts over the base of the maxilla CAROTIDS, AND THEIR BRANCHES. 225 inferior, at the anterior margin of the masseter muscle, and after- wards shapes its course, in a serpentine manner, to the internal canthus of the eye> passing between the muscles and the integu- ments of the face. In this course, the facial artery, sends off the following branches: As it passes by the submaxillary gland it sends several twigs to it: previously it also sends several little branches to the contiguous muscles, as the internal pterygoid, digastric, and so on ; but they are too small to be of much consequence. The Submental branch arises, then, on a level with the base of the lower jaw; it advances forwards under the origin of the mylo- hyoides, and above the anterior belly of the digastricus. It sends several branches to these muscles, some of which anastomose with the ranine artery; behind the symphysis of the jaw it anastomoses with its fellow, it then mounts over the chin, to which and to the lower lip it is distributed, anastomosing there with the inferior coronary artery of the mouth,, and with the inferior maxillary which comes out from the anterior mental foramen in the lower jaw. When the facial artery has got upon the face, it sends back- wards a small branch to the lower part of the masseter muscle. Somewhat above this it sends forwards a branch called the Infe- rior Labia], which is distributed, upon the middle of the chin. When it gets on a level with the corner of the mouth, but some- times lower down, it sends forward, under the depressor anguli oris, the Inferior Coronary Artery, to the lower lip, which fre- quently supplies the place of the inferior labial entirely ; but when the latter is large, the coronary is small in proportion : a few lines higher up the facial sends forward a third branch, the Superior Coronary, which goes to the upper lip. These coronary arteries are very tortuous, and are distributed by many branches in the substance of the lips: by anastomosing with their congeners of the other side, they surround the mouth completely. The supe- rior coronary artery, as it passes under the nose, sends upwards one or more small branches to the integuments of its orifice and, septum.. After this, the facial artery, in ascending towards the internal canthus of the eye, sends a branch to the ala nasi, and another to anastomose with the infra-orbitar artery. It, finally, terminates at the internal canthus of the eye by anastomosing with the branches 20* 226 CIRCULATORY SYSTEM. of the ophthalmic, which come out there upon the side of the root of the nose. Several ramuscles, which are too small to merit spe- cial description, are given by the facial to the integuments and muscles of.the face, and to the lower eyelid. The Inferior Pharyngeal Artery (Art. Pharyngea Inferior, as- cendens) is one of the smallest of the original branches of the ex- ternal carotid, and generally arises opposite to the lingual; but there is much variety in the latter respect, it being sometimes higher up or lower down, and not unfrequently a branch of one of the other arteries, instead of being an original trunk. It ascends on the side of the pharynx, between the external and the internal carotid, and is covered by the stylo-pharyngeus muscle. It is principally distributed on the constrictor muscles of the pharynx, and upon their lining membrane. But one of its branches, called the Posterior Meningeal Artery, ascends through the posterior foramen lacerum of the cranium, between the jugular vein and the pneumo-gastric nerve, and is distributed on the continguous dura mater. The Occipital Artery (Arteria Occipitalis) is a very considera- ble trunk, which comes from the external carotid, generally oppo- site to the facial, and is spent upon the integuments, on the back part of the head. At its root, it is deeply situated in the side of the neck, below the parotid gland, and has the internal jugular vein and the par vagum on its inside. It goes obliquely backwards, in ascending along the posterior belly of the digastricus between the transverse process of the atlas and the mastoid portion of the temporal bone, and is beneath the several muscles which are inserted into the lat- ter, as the sterno-mastoid, the splenius, and the trachelo-mastoid. It is covered, for some distance, by the insertion of the splenius capitis, and becomes at length superficial at the posterior margin of this muscle. The occipital artery is distributed as follows: Shortly after its origin, it sends branches to the digastric mus- cle behind, to the upper part of the sterno-mastoid and to the lvm- phatic glands of the upper part of the neck. While enclosed by the muscles on the back of the- neck, it also sends branches to them, and anastomoses thereby with the vertebral artery; occasion- ally, one of these branches is of considerable magnitude, and has CAROTIDS, AND THEIR BRANCHES. 227 been found descending very loW on the back, between the splenius and the complexus muscle. It also sends a small branch to the dura mater, through the mastoid foramen generally, but sometimes through the posterior foramen lacerum. When the stylo-mastoid artery is wanting, it also detaches a branch through the stylo- mastoid foramen to the internal parts of the ear. The occipital artery, having become superficial at the internal margin of the splenius on the occiput, ascends on the latter bone towards the vertex in a tortuous manner, sending off, on each side, many small ramifications. It ends by anastomosing with the posterior temporal artery. The Posterior Auricular Artery (Art. Auricularis Posterior) arises a little above the last, at the lower edge of the parotid gland, from the external carotid, and is one of its smallest branches. It ascends backwards enclosed by the parotid gland, and after- wards between the meatus auditorius externus and the mastoid bone: at the latter place, it sends a ramification to the internal side of the external ear; it then ascends and is distributed, by small branches, on the contiguous integuments of the side of the head. While still involved in the parotid gland, it sends some small ramifications through the meatus externus to its lining mem- brane and the membrana tympani. It then detaches a branch through the stylo-mastoid foramen, from which the whole artery is also named Stylo-Mastoid; but this branch, as stated, sometimes comes from the occipital. The stylo-mastoid passes along the aqueduct of Fallopius, detachiqg its arterioles to the tympanum and to the labyrinth. The External Carotid having given off these trunks, penetrates vertically through the inner margin of the parotid gland, and gives to it several small twigs. When it arrives on a line with the neck of the lower jaw, it divides into two large trunks; one of them, the Internal Maxillary, goes to the parts within the ramus of the lower jaw; the other, being smaller, is the Temporal Artery. The Temporal Artery (Arteria Temporalis) continues to ascend through the substance of the parotid, but becomes superficial in 228 CIRCULATORY SYSTEM. front of the meatus externus, in mounting over the root of the zygoma; it is then distributed to the integuments on the side of the head. It frequently sends off one or two ramifications, of but little volume, to the masseter muscle. Just above its root, and while surrounded by the parotid, a branch of some importance, the Transverse Facial, (Transversalis Faciei,) leaves it, and crosses, horizontally, the masseter muscle, just below the parotid duct, sometimes above it. This branch is distributed to the adjacent integuments and. muscles, and terminates in front by anastomosing with the facial and the infra-orbitar artery. A little below the zygoma, the Middle Temporal artery (Art. Temp. Media) comes off from the Temporal, and, ascending with the parent trunk, perforates the temporal fascia at the upper mar- gin of the zygoma, and is distributed to the temporal muscle by many ramifications, which anastomose with the deep-seated tem- poral arteries. After this, some small twigs, called Auricular, go to the external ear from the trunk of the temporal artery. The temporal artery, having ascended for an,inch or so between the aponeurosis of the temporal muscle and the skin, it divides into an Anterior and a Posterior Branch. The former ascends towards the side of the os frontis, and is distributed in ramuscles to the orbicularis palpebrarum, the anterior belly of the occipito-frontalis, and the integuments of the front of the cranium, anastomosing with the frontal artery and the temporal of the other side. The posterior branch is distributed on the integuments of the middle of the side of the cranium, anastomosing with the anterior branch, with its fellow of the other side, and with the occipital artery. The Internal Maxillary Artery (Arteria Maxillaris Interna) winds round the neck of the lower jaw, and, passing between the pterygoid muscles, proceeds in a tortuous manner to the deepest points of the zygomatic fossa. The first part of its course is hori- zontally inwards; it then ascends in front of the pterygoideus ex- ternus to the bottom of the temporal bone, or the spinous process of the sphenoidal: it then passes forwards, within the temporal muscle, to the upper part of the pterygo-maxillary fossa. It sends off several branches, and commonly in the following order:— CAROTIDS, AND THEIR BRANCHES. 229 1. The Arteria Tympanica, to the tympanum, through the gle- noid fissure. 2. The Arteria Meningea Parva, to the dura mater, through the foramen ovale. It is most frequently a branch of the next. 3. The Arteria Meningea Magna, or Media, to the dura mater, through the foramen spinale. This branch having entered the cra- nium, is distributed upon the dura mater in the manner marked off by the furrows upon the internal face of the temporal, the parietal, and the frontal bones. One of its branches enters the aqueduct of Fallopius, through the Vidian Foramen, and is distributed upon the internal parts of the organ of hearing, anastomosing with the stylo- mastoid artery. 4. The Arteria Maxillaris, or Dentalis Inferior, descends along the internal face of the ramus of the lower jaw, and having sent off some ramifications of small size to the contiguous muscles and the lining membrane of the mouth, it enters the posterior mental foramen with the inferior dental nerve. Going along the canal in the substance of the lower jaw, it detaches successively from its superior margin ramifications to the teeth. At the anterior mental foramen a trunk is sent forward as far as the symphysis, which supplies in its course the canine and incisor teeth; the remainder of the inferior maxillary artery comes out at the foramen, and sup- plies the chin, anastomosing with the facial artery. 5. The Arteriae Temporales Profundae are two in number. The first of them, called Posterior, arises next to the inferior maxillary. It is concealed between the external pterygoid and the temporal muscle for some distance; it then ascends in the posterior part of the temporal fossa, beneath the temporal muscle, and is minutely dis- tributed upon it. The Anterior deep temporal artery is separated from the posterior, in its origin from the external maxillary, by the pterygoid and the buccal arteries. It arises near the pterygo- maxillary fossa; and, ascending between the temporal muscle and the fore part of the corresponding fossa, it is minutely distributed upon the former, anastomosing with the posterior deep, and with the middle temporal artery. 230 CIRCULATORY SYSTEM. 6. The Arteriae Pterygoideae arise after the posterior deep tem- poral. They vary considerably in regard to number, size, and origin, and are distributed upon the pterygoid muscles, as their name implies. One of their branches, which is sometimes an inde- pendent trunk from the internal maxillary, goes between the poste- rior margin of the temporal muscle and of the neck of the lower jaw, in front of the latter, to be distributed upon the internal face of the masseter muscle. 7. The Arteria Buccalis, sometimes a branch of the internal maxillary, but frequently coming from one of its trunks, either the alveolar or the anterior temporal, passes along the external face of the upper jaw, and distributes its branches to the bucci- nator and zygomatic muscles, and to the lining membrane of the mouth. 8. The Arteria Maxillaris Superior, or Alveolaris, proceeds downwards and forwards in winding round the tuber of the up- per jaw bone. It first sends some ramifications through the bone to the roots of the great and small molar teeth, and to the lining membrane of the maxillary sinus; it then passes forwards along the gums, near the buccinator, and gives ramifications to them and to the contiguous muscles. 9. The Arteria Infra-orbitalis comes from the internal maxillary, at the upper part of the pterygo-maxillary fossa ; it sends some in- considerable ramifications to the fat and the periosteum of the or- bit, through the spheno-maxillary fissure. It then enters the infra- orbitary canal, and passes through it with the infra-orbitary nerve. On arriving near the anterior orifice of the canal, it detaches down- wards a branch which goes to the canine and the incisor teeth, and to the lining membrane of the antrum. It then gets to the face below the origin of the levator labii superioris muscle, and is distributed upon the muscles in front of the upper maxilla, anasto- mosing with the facial and with the ophthalmic artery. 10. The Arteria Palatina Superior descends through the pos- terior palatine canal, and having reached the mouth, leaves some ramifications with the soft palate: it then advances between the bones and the lining membrane of the roof of the mouth, and SUBCLAVIAN, AND ITS BRANCHES. 231 disperses itself in several small twigs; one of which passes through the foramen incisivum into the nostril. 11. The Arteria Pharyngea Superior is sometimes a branch of the last, and is spent upon that portion of the pharynx bordering on the pterygoid processes. 12. The Arteria Spheno-Palatina is the terminating trunk of the internal maxillary; it enters the nose through the spheno-palatine foramen, and divides into two branches, which are minutely dis- tributed over the Schneiderian membrane. One of them descends along the septum narium; the other along the external margin of the posterior naris, and divides into two principal ramuscles, one of which is dispersed along the middle turbinated, and the other along the inferior turbinated bone. SECT. III.—OF THE SUBCLAVIAN ARTERY, AND ITS BRANCHES. The Subclavian Artery (Arteria Subclavia) of the right side having arisen from the innominata, and that of the left from the aorta, they each go over the first rib of their respective sides, ad- hering closely to it, in the bottom of the interval between the sca- lenus anticus and medius muscle. The right subclavian is much shorter, and more superficial than the left, from its origin to the scaleni muscles. Near the latter they are each covered in front by the sternal end of the clavicle, by the sterno-hyoid and thyroid muscle, and by the subclavian vein of the corresponding side; be- hind they are separated from the vertebral column by the longus colli muscle; below them is the pleura, the left artery being in con- tact with it for its whole passage in the thorax ; and on their in- ternal side is the primitive carotid. The subclavian of the right side is crossed near the scalenus anticus by the par vagum; the phrenic nerve also goes in front of it, but on the internal edge of the scalenus. The subclavian of the left side having a course al- most vertical from its origin to the interval of the scaleni muscles, is nearly parallel with and behind, the primitive carotid of that side; the phrenic nerve has the same relative position with it as on the right side; but the par vagum goes parallel with, and in 232 CIRCULATORY SYSTEM. front of the subclavian artery, for some distance along the root of the latter. At the inner margin of the Scaleni Muscles the Subclavian gives off a cluster of trunks; to wit, the Vertebral; the Inferior Thyroidal; the Superior Intercostal; the Internal Mammary; and the Posterior Cervical Artery. They sometimes arise distinctly, and after the order mentioned : but there is too great a diversity in subjects to establish any rule on these points. 1. The Vertebral Artery (Arteria Vertebralis) is the most vo- luminous of the branches of the Subclavian. Immediately after its origin it ascends on the side of the spine, and enters the canal of the transverse processes of the neck at the sixth vertebra. Pur- suing this course, it gets into the cavity of the cranium through the foramen magnum occipitis, and is distributed to the brain in the manner mentioned in the description of that organ. While in the canal of the transverse processes, it sends off se- veral branches to the heads of the contiguous muscles, and to the medulla spinalis of the neck. The vertebral artery, like some others, is spindle-shaped, its size augmenting as it recedes from its origin; this imparts some advantage to the current of the blood. 2. The Inferior Thyroid Artery (Arteria Thyroidea Inferior) arises from the upper face of the subclavian, and goes to the thy- roid gland. It ascends at first on the internal margin of the sca- lenus medius muscle, and then turns suddenly inwards between the vertebras and the great vessels of the neck. In this course several unimportant twigs are sent from it to the contiguous parts. Near its root it detaches the Anterior, or the Ascending Cervical Artery, which going up the neck is spent upon the heads of the muscles arising from the transverse processes, as the scaleni, the longus colli, and so on. The inferior thyroidal then gets to the thyroid gland, and is very minutely distributed to it, anastomosing with the other arteries which supply the same organ. 3. The Superior Intercostal Artery, (Arteria Intercostalis Supe- rior,) arising from the under surface of the subclavian opposite the inferior thyroid, descends across the neck of* the first rib, and di- SUBCLAVIAN, AND ITS BRANCHES. 233 vides into two branches, which supply the two upper intercostal spaces: each of them also sends backwards near the vertebra a small trunk to the muscles of the back. 4. The Internal Mammary Artery (Arteria Mammaria Interna, Thoracica) descends at first along the internal margin of the sca- lenus anticus; having then got fairly into the cavity of the thorax, it continues to descend across the posterior face of the costal car- tilages, parallel with, and about nine lines from, the outer edge of the sternum, between the triangularis sterni and the intercostal muscles. In this course, besides some distinct twigs to the anterior medi- astinum, it sends a branch (Phrenica Superior) which accompany- ing the phrenic nerve between the pleura and the pericardium, reaches finally the diaphragm, and is spent upon it. At each intercostal space which it crosses, the internal mammary sends outwards a branch, which is spent upon the fore part of the inter- costal muscles, and anastomoses with the corresponding intercostal artery: other branches also leave it at each space, which getting forwards near the sternum, are distributed upon the pectoralis major, and upon the contiguous muscles. The last of these branches, according to M. H. Cloquet, goes transversely across the ensiform cartilage, and, having anastomosed with its fellow, descends between the peritoneum and the linea alba to the suspen- sory ligament of the liver. On a line generally with the anterior extremity of the fifth rib, the internal mammary divides into two principal branches; the most exterior of which, descending along the cartilaginous margin of the thorax, is distributed in small twigs to the origin there of the diaphragm and of the transverse muscle of the abdomen. The internal branch reaches the posterior face of the rectus abdominis muscle, and is dispersed upon it: some of its branches go as low as the umbilicus, to anastomose there with the epigastric artery. 5. The Posterior Cervical Artery (Arteria Cervicalis Posterior, Transversa) is of a very unsettled origin, but comes most fre- quently either from the subclavian itself, or from the inferior thy- roid. It is but small in some subjects, owing to its place being supplied by branches from the adjoining arteries. Vol. II.—21 234 CIRCULATORY SYSTEM. It crosses horizontally the root of the neck on the outer face of the scaleni muscles above the subclavian artery. It gets under the anterior margin of the trapezius, and is there divided into two principal branches; the ascending one is spent upon the trapezius and the levator scapulae; the other descends along the base of the scapula, and is spent in ramifications upon the rhomboidei and the serratus major muscle. Several branches of minor size and im- portance are sent off from the posterior cervical artery to the mus- cles on the back of the neck and thorax. The Subclavian Artery having sent off the preceding branches, then escapes from the thorax between the scaleni muscles, and gets to the arm-pit betweeen the first rib and the subclavius mus- cle. The trunk of it is then continued downwards through the axilla, and at the inner side of the arm to the elbow joint. From the scaleni muscles to the elbow its relative position is as follows: When it first appears between the scaleni, it is bounded above and behind by the collected fasciculi of the axillary plexus of nerves. In front it is separated from the subclavian vein by the insertion of the scalenus anticus. It is placed at the bottom of the depression between the sterno-mastoideus and the trapezius, being covered by the skin, the platysma myodes, and some loose cellular substance below the latter. It then descends between the first rib and the subclavius muscle; escaping from below the latter, it is covered in front by the outer margin of the pectoralis major until it reaches the lower part of the axilla; and in this course it has the following relation to other parts: it passes then under the inser- tion of the pectoralis minor, under the shoulder joint, then along the internal face of the coraco-brachialis muscle; it has the axil- lary vein in front of it, and the axillary nerves plaited around it as far down as the coracoid process, when they begin to disperse. This artery in emerging from the axilla is placed upon the ante- rior face of the insertion of the latissimus dorsi: it then runs out the length of the coraco-brachialis, and is afterwards conducted along the inner margin of the biceps flexor cubiti and its tendinous termination; it lies upon the anterior face of the brachialis inter- nus ; and goes beneath the aponeurosis coming from the tendon of the biceps at the bend of the arm. In the arm it is concealed only by the integuments and fascia, and is bordered internally by the brachial vein and the median nerve. AXILLARY, AND ITS BRANCHES. 235 This great trunk of the upper extremity loses the name of sub- clavian, to be called Axillary Artery, (Art. Axillaris,) from the subclavian muscle to the lower margin of the arm-pit: and from the latter place to the elbow joint, it is named Brachial Artery, (Art. Brachialis.) It sends off many interesting branches to the thorax, to the shoulder, and to the arm; and, finally, terminates a little below or at the elbow joint by bifurcating. Of the Branches of the Axillary Artery. 1. The Superior Scapular Artery (Art. Dorsalis Superior Sca- pula) varies considerably in its origin. Sometimes it is a branch of the subclavian, sometimes of the inferior thyroid, and it fre- quently comes from the upper part of the axillary; so that it can- not be referred, with strict propriety, to any determined origin. When it comes from the axillary, it is very tortuous, and has to ascend to its destination, which removes it entirely from any in- terference with the course of the subclavian over the first rib, and over the upper head of the serratus major muscle. But in the other cases, it goes transversely backwards and outwards, some- what below the posterior cervical, and along the posterior inferior margin of the clavicle, being covered by the sterno-mastoideus, the platysma myodes, and the trapezius; consequently, it is just in the way of the incisions which are made for reaching the subcla- vian artery, from above the clavicle. It reaches the superior costa of the scapula near the root of the coracoid process, and passing through the notch there, is distri- buted, by one large branch, upon the supra-spinatus muscle; and by another, which goes across the anterior margin of the spine of the scapula, to the infra-spinatus muscle. In its course, it sends off several small ramifications to contiguous parts. 2. The External Mammary Arteries (Art. Mammaria seu Tho- racicce Externce) arise from the axillary, between the subclavius and the pectoralis minor muscle. They are four principal trunks, which go uniformly to certain parts, but vary considerably in their origin; for sometimes the latter is distinct in the case of each artery, but frequently otherwise. Their distribution is as follows: a. The Thoracica Superior is distributed to the upper part of the pectoralis major muscle, and to the pectoralis minor. Some 236 CIRCULATORY SYSTEM. of its branches reach the mamma in the female, and anastomose with the internal mammary and with the intercostals. b. The Thoracica Longa descends along the posterior face of the pectoralis major, between it and the serratus magnus. It gives many branches to the lower part of the pectoralis major, to the integuments, and, in the female, to the mamma: anastomosing likewise with the internal mammary and with the intercostals. c. The Thoracica Acromialis, immediately after its origin, makes for the fissure between the deltoid and the great pectoral muscle, and divides there into an ascending and a descending branch. The former reaches the clavicle, and is partly distributed superficially along it, partly to the contiguous muscles, and to the shoulder articulation. The other branch follows the cephalic vein along the interstice between the deltoides and pectoralis major, and is, finally, distributed to these muscles and to the integuments. d. The Thoracica Axillaris is irregular, both in regard to the number of its branches and to their origin. Instead of a distinct origin by one or more trunks from the axillary artery, the branches belonging to the name of thoracica axillaris, are sometimes derived from the other thoracic arteries. They are generally distributed only to the fat and the lymphatic glands in the axilla. They oc- casionally exist primitively as a large trunk, which runs on the scapular face of the serratus major the whole length of the sca- pula, and is distributed to the adjacent muscles, and to the fat and glands of the axilla. 3. The Scapular Artery (Arteria Scapularis communis, Sub- scapularis) arises from the axillary below the shoulder joint, at or near the anterior margin of the subscapularis muscle. Giving off some inconsiderable branches to the lymphatic glands of the arm- pit, it descends along the anterior margin of the subscapularis, and is distributed to it, to the latissimus dorsi, and to the teres major and minor muscles. A little below the neck of the scapula, it detaches a large trunk, the Dorsalis Inferior Scapulae, which, winding around the inferior costa of the bone over the anterior margin of the subscapularis and the teres minor, reaches the fossa infra-spinata. This trunk then divides into two branches: one of which is distributed super- ficially between the aponeurosis and the infra-spinatus, and the other more deeply near the dorsum of the bone: one of the ramus- BRACHIAL, AND ITS BRANCHES. 237 cles of the latter ascends beneath the neck of the acromion to anastomose with the Dorsalis Superior Scapulae. 4. The Anterior Circumflex Artery (Art. Circumflexa Anterior, Articularis Anterior) is about the size of a crow quill, and arises from the axillary just above the tendon of the teres major and of the latissimus dorsi. It adheres closely to, and surrounds the front of the neck of the os humeri, passing between it, the coraco- brachialis, and the short head of the biceps. It then divides into several branches, some of which go to the deltoides, and anasto- mose there with the posterior circumflex; others go immediately to the articulation, and either terminate on it or ascend to the muscles on the dorsum of the scapula, where they anastomose with the scapular arteries. 5. The Posterior Circumflex Artery (Art. Circumflexa Poste- rior) is much larger than the last, and arises from the axillary somewhat below it. It surrounds the posterior face of the neck of the os humeri, passing between it and the long head of the tri- ceps muscle, below the insertion of the teres minor. Many of its ramifications go to the capsular ligament of the articulation and to the muscles adhering to it. But this artery is principally intended for the deltoid muscle, to the internal face of which the most of its branches go. It anastomoses with the anterior circumflex, and with the scapular arteries. In some cases, the posterior circumflex arises from the axillary below, instead of above the tendinous insertion of the latissimus dorsi: when this happens, it commonly gives off the arteria pro- funda major of the arm, and afterwards ascends on the posterior face of the tendon to its appropriate destination. Of the Branches of the Brachial Artery. 1. The Profound Artery (Arteria Profunda Major Humeri, Spi- ralis,) arises from the brachial, a little below the tendinous inser- tion of the latissimus dorsi, and having passed downwards, for a short distance, it enters the interstice between the first and the third head of the triceps muscle, and winds spirally downwards around the os humeri in company with the radial nerve. On the outer side of the arm, it becomes superficial.between the margins 21* 238 CIRCULATORY SYSTEM. of the triceps and of the brachialis internus, and then directs its course between the latter and the supinator longus to the external condyle. In this course, the artery sends several branches to the triceps muscle, to which, indeed, it is principally destined. Near the ex- ternal condyle, it supplies the brachialis internus and the heads of the extensor muscles of the fore-arm, and anastomoses with the recurrent branch of the radial artery. 2. The Small Profound Artery (Art. Profunda Minor) comes from the brachial, two or three inches below the profunda major, but frequently it is only a branch of the latter, and is generally much smaller. It is distributed superficially on the internal face of the triceps at its lower part, and has its terminating branches reaching as far as the internal condyle. 3. The Nutritious Artery (Art. JVutritia) is the next in order from the brachial, and arises from it near the medullary foramen of the os humeri, through which it penetrates, and is distributed to the lining membrane of the bone. It is not larger than a knitting needle. 4. The Anastomotic Artery (Arteria Anastomotica) arises from the brachial below the last, and is larger than it. It lies upon the lower internal part of the brachialis internus muscle, and crosses the ridge leading to the internal condyle in order to reach the de- pression between the latter and the olecranon, where it anastomoses with the ulnar recurrent artery. The preceding is a common arrangement of the branches pro- ceeding from the brachial artery, yet deviations from it are conti- nually met with, in a deficiency or in a redundancy of these col- lateral trunks, and in their mode of origin. An account of all the varieties which are observed here would be almost endless, as qvery subject has some peculiarity. Several small arteries are also sent from the brachial to the coraco-brachialis, the biceps, the brachialis internus, and to the triceps muscles. They, for the most part, are, simply, muscular branches, which are too small and irregular to deserve specifying. A division of the brachial, artery into two trunks, the RadiaP BRACHIAL, AND ITS BRANCHES. 239 and the Ulnar, will be found in a majority of subjects in front of the brachialis internus muscle on a line with the elbow joint: sometimes it occurs nearer the root of the coronoid process. It is, however, by no means rare to see this bifurcation much above the elbow. Examples of it have been witnessed at every point between the latter and the arm-pit; in such cases, the course of the radial artery down the fore-arm is generally much more superficial than usual, as it is placed immediately below the skin. Of the Radial Artery. The Radial Artery (Arteria Radialis) is smaller than the ulnar, and extends from the elbow to the hand. In the upper.half of the fore-arm it is placed at the bottom of the fissure between the supi- nator radii longus and the pronator teres muscle. Having crossed the insertion of the latter, it runs in front of the radius between the tendon of the supinator and of the flexor carpi radialis. Below the styloid process of the radius it runs between the outer end of the carpus and the extensor muscles of the thumb; it then pene- trates to the palm of the hand between the root of the metacarpal bone of the thumb and of the fore-finger, above the abductor indicis muscle. The following branches are sent from the Radial Artery. 1. The Recurrens Radialis arises at the neck of the radius. It winds, externally around the joint between the external condyle and the muscles coming from it, and anastomoses with the spiralis of the humeral artery, being distributed in many collateral branches, to the joint and to the contiguous muscles. 2. Several small and irregular muscular branches arise from the radial artery, in its progress to the wrist: they have no appro- priate names. 3. The Superficialis Volae arises from the radial about the infe- rior margin of the pronator quadratus muscle. It passes superfi- cially over the process of the trapezium to the muscles of the ball of the thumb, and one of its terminating branches joins the arcus sublimis. Sometimes the superficialis volae is the principal branch of the radial. 240 CIRCULATORY SYSTEM. 4. The Dorsalis Carpi arises from the radial at the carpus, runs across the back of the latter below the extensor tendons, and de- taches the posterior interosseous arteries of the back of the hand. They anastomose with branches from the ulnar and interosseous arteries of the fore-arm. 5. The Magna Pollicis, a terminating branch of the radial, comes from it in the palm of the hand just at the root of the meta- carpal bone of the thumb. It runs beneath the abductor indicis, and at the head of the metacarpal bone divides into two branches which go respectively along the sides of the thumb to its extremity, where they anastomose and terminate. 6. The Radialis Indicis, arising at the same place with the latter, runs along the metacarpal bone of the fore finger, and along the radial side of the same finger to its extremity. 7. The Palmaris Profunda is the third terminating branch of the radial artery. It arises near the same place with the last two, crosses the hand between the metacarpal bones and the flexor tendons; thus forming the Arcus Profundus, from which branches proceed to the interossei muscles; and which ends on the ulnar side of the palm of the hand by a connexion, with the Arcus Superficialis. Of the Ulnar Artery. The Ulnar Artery, (Arteria Ulnaris,) one of the forks of the brachial at the elbow, passes more in a line with it than the radial artery does. It goes, immediately after its origin, under several of the muscles of the internal condyle, to wit: the pronator teres, flexor radialis, flexor sublimis, and palmaris longus, and between the flexor sublimis and profundus digitorum, being deeply seated; getting from beneath the flexor sublimis, it afterwards runs parallel with the ulna, or nearly so, lying on the flexor profundus between the flexor ulnaris and the ulnar margin of the flexor sublimis, and concealed two-thirds of the way down the fore arm by the over- lapping of these muscles. At the thin part of the fore arm, com- monly called the wrist, it is superficial, and may be felt pulsating SUBCLAVIAN, AND ITS BRANCHES. 241 in the living body at the radial margin of the tendon of the flexor ulnaris. The ulnar artery, at the carpus, takes a very different course from the radial; for it passes over the anterior annular ligament of the carpus just at the radial side of the os pisiforme, to which it is held by a small ligamentous noose; it then proceeds to the palm of the hand. Between the aponeurosis palmaris and the flexor tendons it forms that curve from the ulnar to the radial side of the hand called the Arcus Sublimis. This curve commonly begins a little beyond the anterior margin of the annular ligament, and pre- senting its convexity forwards, terminates about the middle of the ball of the thumb at its inner maro-in. The branches sent from the ulnar artery are as follow : 1. The Recurrens Ulnaris arises from the ulnar about the lower part of the tubercle of the radius, and, winding upwards, is dis- tributed in small branches to the muscles of the internal condyle. One of its ramuscles goes between the internal condyle and the olecranon process to anastomose with the arteria anastomotica of the humeral. 2. The Interossea arises from the ulnar, just below the other.. It is a large trunk, and proceeds but a little distance when it di- vides into two principal branches, called anterior and posterior in- terosseal arteries. a. The Interossea Anterior is much the larger; it runs in con- tact with the interosseous ligament to the upper margin of the pro- nator quadratus, giving off branches to the deep-seated muscles of the fore arm in its course. Under the pronator it perforates the interosseous ligament, and distributes branches to the back of the carpus and of the hand, which anastomose with branches of the radial and posterior interosseal. b. The Interossea Posterior is sometimes a separate trunk, arising from the ulnar just above the former. In either case it soon perforates the interosseous ligament to get to the back of the fore arm. Here it sends backwards a Recurrent Branch (Recurrens Interossea) to the back of the elbow, which anastomoses with the recurrens ulnaris and radialis. It then proceeds downwards, be- ing deeply seated and distributed to the different muscles on the 242 CIRCULATORY SYSTEM. back of the fore arm. Some of its branches reach the wrist, and anastomose with the carpal arteries. 3. The ulnar artery, in its descent on the fore arm, sends off many small and irregular muscular branches, called by Pro- fessor Chaussier, Cubito-muscular: they do not require descrip- tion. 4. The Dorsalis Manus leaves the ulnar at the lower end of the fore arm, and passes under the tendon of the flexor ulnaris to the back of the hand. It there meets ramuscles of the radial and interosseous, and conjointly they supply with very small branches the back of the wrisf, of the metacarpus, and of the fingers. 5. As the Arcus Sublimis is about beginning, the ulnar artery sends superficial but small branches to the integuments of the palm; and a little farther on, a considerable branch, which dives into the bottom of the palm, through the muscles of the little finger, and joins the ulnar extremity of the arcus profundus: this is the Cubi- talis Manus Profunda of Haller. 6. The Arcus Sublimis then sends a branch to the ulnar side of the little finger. Afterwards in succession three digital branches are sent off, which, arriving at the interstices between the heads of the several metacarpal bones, each divides into two branches to supply the sides of the fingers which are opposite to each other; one branch is called Digito-radial, the other Digito-ulnar, accord- ing to the side of the finger on which the artery may be placed. In this way the radial side of the little finger, both sides of the ring finger, both sides of the middle finger, and the ulnar side of the fore finger are supplied. The digital arteries, before they divide, receive each a small branch from the arcus profundus. The digito-radial, and the digito-ulnar arteries, pass along the sides of the fingers in front to their extremities; at the joints and extremities, anastomoses be- tween the arteries of the two sides of the same finger frequently occur. The arcus sublimis terminates on the radial side of the palm by SUBCLAVIAN, AND ITS BRANCHES. 243 a branch which joins the inner branch of the Arteria Magna Pol- licis of the Radial. The most frequent distribution of the arteries of the hand is what has just been described : anatomists are, however, not all agreed on this point. It would probably be more just to say, that this occurs more frequently than any other single arrangement. The varieties, in fact, are so great, that before a hand is opened, it is not possible to know in what manner its arteries will be dis- tributed. Sometimes the Radial Artery furnishes one half of the arcus sublimis, and the Ulnar the other half. On other occasions, the interosseous artery is continued as a large trunk over the liga- ment of the wrist, or the superficialis volas to join the arcus subli- mis, and to complete the digital arteries. SECT. IV.—BRANCHES OF THE DESCENDING THORACIC AORTA. The Aorta, in its course from the lower part of its curvature to the crura of the Diaphragm, gives off several branches to the vis- cera and to the parietes of the thorax. The Bronchial Arteries (Arteria Bronchioles) are the nutri- tious vessels of the lungs. There is commonly one for each lung, but sometimes two or more. The right arises frequently from the superior aortic intercostal artery, instead of from the aorta, while the left comes from the latter : occasionally they have a common root. On either side they follow the course of the bronchus into the substance of the lung; and are distributed along with it, by ramifi- cations which become successively finer and finer, and anastomose with the pulmonary artery ; after the manner mentioned in the de- scription of the lungs. Before they enter the latter, they send some small ramifications to the posterior mediastinum, to the pericardium, and to the black bronchial glands. The (Esophageal Arteries (Arteria (Esophagea) are generally five or six small twigs which come successively from the descend- ing thoracic aorta. They ramify minutely in the substance of the oesophagus, communicating freely with each other: the lowest of 244 CIRCULATORY SYSTEM. them also anastomose around the cardia with the superior artery of the stomach. The Posterior Arteries of the Mediastinum, (Arteria Mediasti- nals Posteriores,) are numerous and small; they come from the anterior face of the aorta, as well as from the branches last men- tioned ; and are spent upon the posterior mediastinum, and upon its contents. The Intercostal Arteries (Arterise Intercostales Inferior es Aortic a) of the aorta supply the ten lower intercostal spaces on each side, as the two upper ones are supplied by the subclavian artery. There is commonly an intercostal artery arising distinctly from the aorta for each space, but sometimes two of them arise from a common trunk. Those for the right side having to cross the spine behind the oesophagus and the vena azygos, are, of course, longer than such as belong to the left. The upper ones on either side have to ascend, in order to reach their destination. Each artery joins the rib near its tubercle, and goes along the groove in its lower margin, between the external and the internal intercostal muscle, for two-thirds of the length of the rib. It then abandons the groove, and divides into several branches, which go to the intercostal muscles and contiguous parts, and anastomose in front with the internal mammary artery. As each intercostal artery passes the head of the rib, it sends a branch backwards, (ramus dorsalis,) between the transverse pro- cesses of the adjoining vertebrae, which penetrates to the posterior face of the trunk, and is distributed to the muscles and skin on the side of the spine. A ramification from this branch enters the in- tervertebral foramen, and is spent upon the medulla spinalis and its membranes. Each intercostal artery also gives off, about the middle of the rib, a branch, (ramus costalis inferior,) much smaller than the trunk. This branch advances along the upper margin of the rib below, and gives ramifications to its periosteum and to the adja- cent intercostal muscles. The last intercostal artery is remarkable for its size. Its origin is concealed by the small muscle of the diaphragm, to which it gives some ramifications: it then passes, at the under margin of the last rib, behind the upper end of the quadratus lumborum mus- BRANCHES OF THE ABDOMINAL AORTA. 245 cle, where it divides into three branches; one of which goes trans- versely to the broad muscles of the abdomen; while the other two descend between the oblique and transverse muscles towards the crest of the ilium, where they anastomose with the lumbar arteries, and with the circumflexa ilii. SECT. V.—OF THE BRANCHES OF THE ABDOMINAL AORTA. The Phrenic Arteries (Arteria Phrenica) are two in number, one for the right and the other for the left side of the diaphragm. They arise singly, but sometimes by a common trunk, from the front of the aorta, immediately on the latter showing itself in the abdomen, between the crura of the diaphragm; consequently, just below the crossing of the muscular fibres, which takes place be- tween the foramina for the aorta and that for the oesophagus. The phrenic arteries ascend along the lesser muscle of the dia- phragm, and give some ramifications to it and to the capsulae re- nales. They then divide each into two leading trunks, which are distributed over the diaphragm, principally on its concave surface. Some small ramifications from them go to the liver and to the lower part of the oesophagus. The two phrenic arteries anastomose with each other: also, with the superior phrenics, coming from the internal mammary; and with the intercostals. Sometimes one or both of them come from the coeliac artery, or its branches. The Coeliac Artery (Arteria Casliaca) is the next branch of the abdominal aorta, and arises immediately below the phrenics, between the crura of the diaphragm, opposite the junction of the last dorsal with the first lumbar vertebra. It is a very large trunk, and goes off at right angles, being placed between the left lobe of the liver and the superior margin of the pancreas. When it is only half an inch long, it is split into three trunks, the Gastric, the Hepatic, and the Splenic; this division is the Tripus Halleri. The Gastric Artery (Arteria Gastrica, Coronaria Ventriculi) is the smallest of the three trunks, and frequently arises from one of the others. It advances forwards and towards the cardiac ori- Vol. II.—22 246 CIRCULATORY SYSTEM. fice, in order to reach the small curvature of the stomach, the course of which it pursues to the pylorus, between the two laminae of the little omentum. It gives off the following branches :— a. Ramifications to the oesophagus, some of which ascend along it into the posterior mediastinum, and anastomose there with the similar branches coming from the aorta; others go transversely, so as to surround the cardia, reach the greater end of the stomach, and anastomose with the vasa brevia. b. The ramifications to the stomach are abundant, but of an in- determinate number, and arising along its lesser curvature, are distributed in winding branches to the anterior and the posterior surfaces of this viscus, between its membranes. c. Not unfrequently the artery which supplies the left lobe of the liver is a branch from the gastric, in which case the latter is much larger than usual. 2. The Hepatic Artery (Arteria Hepatica) is generally con- siderably larger than the gastric, and inclines towards the right side, in order to reach the liver, which it does through the cap- sule of Glisson. It sends off the following branches :— a. The Right Gastric or Gastro-Epiploic Artery (Arteria Gas- trica Dextra) comes from it near the pylorus, and descending be- tween the duodenum and pancreas, reaches the greater curvature of the stomach, to the right half of which, and to the correspond- ing part of the great omentum, it is distributed. In the early part of its course, the right gastric detaches some small ramifications to the pylorus (arteria pylorica ;) also, to the duodenum and to the pancreas (art. pancreatico duodenales.) The latter commu- nicate, by very free anastomoses, with the superior mesenteric artery. After having sent off this branch, the hepatic artery advances to the transverse fissure of the liver, in front of and to the left of the vena portarum. It then divides into a right and a left branch. The former sends off a ramification to the gall-bladder, (art. Cys- tica,) which first reaches its neck, and is distributed, by many arterioles, upon the parietes of this reservoir; the right branch then penetrates deeply into the transverse fissure, and is distributed by many ramifications, throughout the right lobe of the liver. The left branch of the hepatic artery is distributed, in the same man- ner, throughout the left lobe of the liver. BRANCHES OF THE ABDOMINAL AORTA. 247 3. The Splenic Artery (Arteria Splenica) is larger in the adult than either of the other two branches of the cceliac, and goes to the spleen along the superior margin of the pancreas, performing, in this course, several considerable flexuosities. It gives off the following branches:— a. The Pancreatic Arteries, (Art. Pancreatica Media et Sinis- tra) come successively from its inferior margin, as it goes along the pancreas. Their number and size are variable, but commonly they are not bigger than a knitting needle: they penetrate perpen- dicularly into the pancreas, and then subdivide minutely in furnish- ing its structure. b. The Left Gastric Artery (Art. Gastrica Sinistra, Gaslro- epiploica Sinistra) comes from the left extremity of the splenic, and is about the same size with the right gastric artery, but some- times larger. It attaches itself to the left extremity of the stomach, and goes along the left half of its greater curvature, terminating by an anastomosis with the right gastric artery. In this course, it detaches ramifications to the front and to the back of the sto- mach, and to the omentum majus. c. The Short Vessels (Vasa Brevia, Art. Gastrica Breves) come from the splenic, immediately before it enters the spleen, and after it has subdivided for that purpose. They are five or six in number, and are distributed upon the greater extremity of the stomach, between the cardia and the left gastric artery. The anastomoses between the several arteries of the stomach are so free, that a fine injection pushed into one, readily finds its way into all the others. The splenic artery, when it gets to the left end of the pancreas, is divided into a cluster of branches, and in that condition enters the fissure of the spleen, throughout the interior of which it is divided into an infinitude of ramifications. The Superior Mesenteric Artery (Arteria Mesenterica Superior) arises from the aorta, while the latter is still engaged, between the crura of the diaphragm. It is about the same size as the coeliac, and comes off half an inch below it. It is distributed to all the small intestines and to the right side of the large one after the fol- lowing manner: it first passes behind the pancreas, and then in front of the duodenum, to reach the root of the mesentery, between the two laminae of which it divides and subdivides into several 248 CIRCULATORY SYSTEM. series of arches, one after another: they become successively smaller and more numerous till they reach the margin of the intes- tine, where they cease by sending a great many small parallel branches. The trunk of the superior mesenteric artery, in descending be- tween the laminae of the mesentery, describes a considerable cur- vature, the convexity of which is to the left side and downwards, while its concavity is in a contrary direction. It is from the con- vexity of this trunk, that from fifteen to twenty large branches are sent off successively to form the roots of the first row of arterial arches. These branches are shorter, and generally somewhat smaller, the lower down they arise ; and their origins very closely succeed each other. Upon the first row of arches or anastomoses is formed a second more numerous and small, and upon the second row is formed a third still more numerous and small, from which proceed the intestinal branches. Besides the preceding branches, the superior mesenteric artery sends off the following: Near its root several small ramifications arise, which go to the duodenum and to the pancreas, and anastomose there with the other arteries supplying the same organs. From about the middle of the concavity of the superior mesen- teric artery, arise the three Colic arteries called Ileo-colica, Colica Dextra, and Colica Media: the first supplies a cluster of branches to the lower part of the ileum and to the head of the colon, anas- tomosing on the left with the last of the small intestinal arteries and on the right with the colica dextra: the Colica Dextra is smaller than either of the other two branches, and going between the laminae of the mesocolon, supplies the ascending portion of the colon by dividing into two principal branches, one of which anas- tomoses with the ileo-colic artery, and the other with the colica media: the Colica Media, situated between the laminae of the trans- verse mesocolon, and arising higher up than the colica dextra, advances forwards and divides into two principal trunks; one of which supplies that part of the colon in the right hypochondriac region, and the other the remainder of its transverse portion, form- ing an anastomosis with the colica superior of the inferior mesen- teric artery. The arteries which supply the colon differ from those supplying the small intestines, in forming but one row of arches; which, in fact, are produced by the anastomoses spoken BRANCHES OF THE ABDOMINAL AORTA. 249 of, and have, therefore, extremely large meshes. From the con- vexity of these arches, many parallel branches run out to supply the colon, and are very minutely distributed to it. The Capsular Arteries, the Emulgents, and the Spermatics, arise from the aorta, between the superior and the inferior mesenteric. But they will be described after the inferior mesenteric, so as to keep together the account of the arteries of the intestines. The Inferior Mesenteric Artery, (Art. Mesenterica Inferior) generally arises about one inch above the division of the aorta into the two primitive iliacs, and is much smaller than the superior Mesenteric. It inclines downwards to the left side, and gets be- tween the laminae of the mesocolon; it then divides into three branches, called the Left Colic Arteries, from their distribution to the left side of the colon. From their relative situation to each other, they are distinguished into the Superior, the Middle, and the Inferior; sometimes, however, there are but two of these trunks. The Superior Colic (Art. Colica Sinistra Superior) goes hori- zontally towards the colon in the left lumbar region ; having got near the intestine it divides into two branches, one of which ascends to the transverse colon to form the anastomosis with the Colica Media of the upper mesenteric, while the other descends to unite with the colica media sinistra. The middle Colic Artery (Art. Colica Sinistra Media) is sometimes a branch of the supe- rior, and is occasionally wanting; it goes towards the upper part of the sigmoid flexure of the colon, and then bifurcates: one branch ascends to form by anastomosis an arch with the superior colic, while the other branch descends to join the lower colic artery. The Inferior Colic Artery (Art. Colica Sinistra Inferior) goes towards the middle of the sigmoid flexure of the colon, and there, like the preceding, divides into twro branches; one anastomoses with the artery above, while the other joins with the arteries which go to the rectum from the inferior mesenteric. The Superior Haemorrhoidal Artery (Art. Hamorrhoidea Supe- rior, Interna,) is the lowest and the last branch of the inferior me- senteric. It descends between the laminae of the mesorectum, and is resolved into two symmetrical trunks, which radiate by dividing 22* 250 CIRCULATORY SYSTEM. and subdividing on the side of the rectum, and are dispersed in very fine and numerous branches throughout its substance. It anasto- moses with the middle and the inferior haemorrhoidal arteries, also with the lateral sacral. The Capsular Arteries (Art. Capsulares) arise frequently from the aorta just below the superior mesenteric; but quite as often, if not more so, from the emulgents. They are not larger than a crow's quill, and vary from one to three on either side, generally, however, not exceeding one: when they do, they are proportion- ably small. Passing horizontally outwards, they divide into seve- ral small ramifications, which terminate in the capsulae renales. Some of their branches go to the lesser muscle of the diaphragm. The Emulgent Arteries (Art. Emulgentes, Renales,) are two in number, one for each kidney, but sometimes more. They are large but short; arise from the side of the aorta immediately below the superior mesenteric, and pass outwardly in a horizontal direc- tion. The right one is longer than the left, somewhat lower down, and passes behind the ascending cava. They are both, in their course, from the aorta to the kidney, covered in front by the emul- gent vein, and have to pass through a mass of adipose matter. The emulgent sends off some fine ramifications to the adipose matter, which surrounds it, and before it reaches the fissure of the kidney divides into three or four branches, preparatory to its intro- duction into this gland, upon the structure of which it is ultimately distributed by very fine branches. The Spermatic Arteries (Arteriae Spermaticse, Seminales,) arise from the aorta somewhat below the emulgents, but in some cases from the latter themselves. They are two in number, one on each side, and are about the size of a crow quill in the male subject, but smaller in the female. One comes off generally hio-her up than the other; they then descend on the sides of the vertebral column before the psoae muscles, and cross in front of the ureters, being in all this course behind the peritoneum. They are tortuous, and shortly after their origin begin to adhere to the spermatic veins, which adhesion is continued to the testicle. The branches that the spermatic artery sends off in the abdo- men are inconsiderable, consisting in \ery fine twigs to the adja- BRANCHES OF THE ABDOMINAL AORTA. 251 cent adipose matter, to the lymphatic glands, to the ureter, and to the peritoneum. In the male subject it passes with the vas deferens, through the abdominal canal, and reaching the testicle divides into branches which supply the body of this gland and the epididymis. In descending from the external ring to the testis, some small ramifications, to the adjacent parts, leave it. In the female, the spermatic artery does not leave the cavity of the abdomen, but, descending into the pelvis, gets between the laminae of the broad ligament to the ovarium, and is spent principally upon the latter. Some of its branches go to the Fallopian Tube, to the Round Ligament of the uterus, and to the sides of the latter, where they anastomose with the uterine arteries.* The Lumbar Arteries (Arterise Lumbares) are commonly five in number on either side, but seldom less than three, and in their course outwards, correspond with the intercostal arteries. They are much larger than the latter. They arise in pairs from the posterior external face of the aorta, at a point corresponding with the middle of the bodies of the four upper lumbar vertebras, and jiass outwards between the fasciculi of the psoas magnus muscle, to which, to the quadratus lumborum, and the bodies of the verte- brae, they distribute several branches. Sometimes each pair arises by a common trunk from the posterior face of the aorta. As the latter terminates at the fourth lumbar vertebra, the fifth lumbar artery is a branch from the fourth in most instances. At the base of the transverse process each artery divides into two branches, a posterior or dorsal one, and an anterior or lumbar. The dorsal branch, which is smaller than the other, detaches a ra- mification through the intervertebral foramen to the lower part of the medulla spinalis and to the cauda equina: it then gets to the back, where it is spent upon the muscles near the spine. The an- terior lumbar branch advances between the broad muscles of the abdomen to which it is distributed; and runs forwards far enough to anastomose with the epigastric artery. The first lumbar artery is small, and sometimes comes from the last intercostal: it goes a little below the inferior margin of the last rib, and then descends almost vertically between the peritoneum * The spermatic artery is spindle-shaped, the smallest end being the origin; this favours the flow of blood in it, which would otherwise suffer from so much friction. 252 CIRCULATORY SYSTEM. ,and the transversus abdominis muscle. The lower lumbar arteries anastomose with the circumflexa ilii, and with the superficial branches of the gluteal. The Middle Sacral Artery (Arteria Sacra Media) is generally not so large as a lumbar; it arises from the centre of the bifurca- tion of the aorta into the two primitive iliacs, or else a line or two above it, behind. It descends, in front of the middle line of the fifth lumbar vertebra and of the sacrum, to the coccyx ad- hering to the surface of these bones, and performing some flex- uosities. It sometimes happens that the last pair of lumbar arteries comes from it, or at least one, according to Meckel, more commonly the left: in which case the sacral is of unusual size. The sacral afterwards sends off, to the right and left, a pair of branches for each pair of sacral foramina. They run across the sacrum, send branches to it, anastomose with the lateral sacral arteries, and then penetrate to the cauda equina. The middle sacral artery is lost at the inferior end of the coccyx, in the fat and cellular tissue of the part. SECT. VI.—OF THE PRIMITIVE ILIAC ARTERIES, AND THEIR BRANCHES. The Primitive Iliac Arteries, (Art. lliaca Primitiva, communes,) one on each side, are, as mentioned, the terminating trunks of the abdominal aorta. They extend from the lower part of the fourth lumbar vertebra to the sacro-iliac junction, or near it, where they divide into two trunks, the Internal and the External Iliac. The primitive iliac is bounded on the outer side by the psoas magnus muscle, and behind by the primitive iliac vein; it is crossed at its lower part by the ureter. No branches deserving of especial notice are sent from it before it bifurcates; such as exist are very small, and go simply to the parts immediately con- tiguous. The right artery crosses in front of the root of the left iliac vein. INTERNAL ILIAC ARTERY, AND ITS BRANCHES. 253 SECT. VII.—OF THE INTERNAL ILIAC, OR HYPOGASTRIC ARTERY. « The Internal Iliac Artery {Art. lliaca Interna,-Hypogmti ica) descends from the front upper part of the sacro-iliac junction to the lower part of the same articulation. In this descent, it is bounded behind by the sacral plexus of nerves, and gives off se- veral arterial trunks; but the manner by which the last is accom- plished is much varied in different subjects. For the most part, it is an inch or more long before any important branches leave it; it is then frequently divided into two principal trunks, an anterior and a posterior, from which proceed the several branches that supply the internal and the external parts of the pelvis. The rule of ori- gin of the secondary trunks from these two principal ones, even when the latter exist, is not fixed ; for sometimes they arise from one, sometimes from the other, and then again from the trunk of the hypogastric itself. ' /thyy**^(h.\ fht.cS.uJi Cc^oU-in*-*, & -juJ- /P4-%, The Ilio-Lumbar Artery (Art. Mo Lumbaris) is commonly the first branch of the hypogastric, or of its posterior trunk. It ascends outwards and backwards behind the psoas magnus mus- cle, and there divides into two branches, a superior and an infe- rior. The former continues to ascend between the psoas magnus and the iliacus internus muscle, to which, and to the quadratus lumborum, it distributes branches: it also sends ramifications into the spinal cavity, and anastomoses with the lower lumbar arteries; sometimes it supplies the place of the last lumbar entirely. The inferior branch going outwardly, is divided into two orders of ra- mifications which supply the iliacus internus muscle, on its sur- face and more deeply; also the os ilium by a ramuscle which pe- netrates the nutritious foramen of the latter. The inferior branch anastomoses with the circumflexa ilii of the external iliac. The Lateral Sacral Arteries (Arteria Sacra Laterales) arises next, either from the hypogastric or from its posterior trunk: their number is commonly equal to that of the foramina on the side of the sacrum in front, though they may come from only one or two roots. They cross in front of the sacrum, and divide into branches, some of which anastomose with the middle sacral artery, while 254 CIRCULATORY SYSTEM. others enter the foramina of the sacrum, to be spent on the lower part of the cauda equina. The Obturator Artery (Arteria Obturatoria) comes commonly from the hypogastric or from one of its principal trunks; in some cases it arises from the epigastric or from the external iliac, near Poupart's ligament. In the first cases it passes forwards parallel with the brim of the pelvis, and in the latter cases it descends be- hind the superior ramus of the pubes. Whatever may be the con- dition of its origin, it gets from the pelvis through the upper part of the thyroid foramen over the superior margin of the obturator internus muscle, having previously sent off some in- considerable ramifications to the periosteum and the contiguous muscles. It emerges from the pelvis on the upper margin of the obturator externus muscle, and then divides into two principal trunks. The posterior descends along the external margin of the obturator ex- ternus muscle, to which it gives ramifications; it likewise sends some branches to the heads of the muscles coming from the tuber of the ischium, and thereby anastomoses with the sciatic artery; other branches are spent upon the hip joint, one of which gets into the cavity of the latter through the notch at the lower part of the acetabulum, and is spent upon the adipose matter in its bottom. The anterior branch goes to the heads of the adductor muscles, to the pectineus, to the obturator externus, and to the integuments of the upper internal part of the thigh. Near its origin this branch sends a ramification along the internal margin of the thyroid fora- men to anastomose with the posterior branch, so that the foramen, is surrounded by an arterial circle. The Middle Haemorrhoidal Artery (Art. Hcemorrhoidea Media) varies in its origin, being sometimes from the hypogastric itself, and, on other occasions, from one of its branches, as the gluteal, ischiatic, &c. It descends on the fore part of the rectum, opposite the lower fundus of the bladder in the male, and is distributed by branches to the rectum, to the vesicula seminalis, and to the pros- tate gland. In the female it dispenses branches to the vagina. It is called middle, from its position between the upper and the lower haemorrhoidal arteries. In both sexes, the branches which it sends to other parts besides INTERNAL ILIAC ARTERY, AND ITS BRANCHES. 255 the rectum, frequently arise from other arteries, and in a man- ner which causes them to have distinct appellations, as vagi- nal, &c. The Vesical Arteries (Arterias Vesicoles) consist in several rami- fications, coming from what was the umbilical artery of the foetus, but which, in the adult, with the exception of a short space near its origin, is converted into a "ligamentous chord. These branches ramify upon the parietes of the bladder; one of them more volu- minous than any other, and called, by M. Chaussier, vesico-prosta- tic, gains the lower fundus of the bladder; sends branches to it, to ' the prostate, to the vesicula seminalis, and to the commencement of the urethra. The Uterine Artery (Arteria Uterina) arises from the hypogas- tric, or one of its branches, near the vesical, sometimes before, and on other occasions subsequent to them. Being peculiar to the female sex, its size varies according to the individual being in a state of pregnancy or not: in the latter stages of gestation it is as large as any other branch of the hypogastric. It goes inwards towards the superior part of the vagina, to which it gives some ramifications; it then ascends between the laminae of the broad ligament, in a tortuous manner along the side of the uterus, and divides into many branches which are distributed through the tissue of this organ. It anastomoses with the corre- sponding arteries of the other side, and with the branches of the spermatic artery which go to the Fallopian tube and to the ova- rium. Besides the preceding, the Hypogastric, or Internal Iliac artery sends off two large branches, the Gluteal and the Ischiatic, which terminate it. In many subjects they are the direct continuation of the two primitive trunks, into which the hypogastric is frequently originally divided. The Gluteal Artery, (Arteria Glutea,) shortly after its origin, issues from the pelvis above the pyriformis muscle, at the upper part of the ischiatic foramen, where it adheres closely to the edge of the bone. When it first gets to the dorsum of the ilium, it is covered by the gluteus magnus muscle, and lies at the posterior 256 CIRCULATORY SYSTEM. margin of the gluteus minimus, precisely under a line drawn from the posterior superior spinous process to the top of the trochanter major. It almost immediately afterwards divides into two prin- cipal trunks. One of these trunks, the more superficial, advances between the gluteus medius and the magnus, and distributes branches to them; also, to the posterior margin of the magnus, where it comes from the posterior sacro-sciatic ligament. The more deeply-seated trunk goes forwards between the gluteus medius and minimus, and subdivides into three orders of branches for their supply. One set follows the superior margin of the gluteus minimus to- wards the anterior superior spinous process; another set passes nearer the middle of the gluteus minimus; and the third set still lower down upon the dorsum of the ilium, above the acetabulum; some of the ramifications go to the capsular ligament of the joint, where they anastomose with branches from the femoral artery. The Ischiatic Artery (Arteria Ischiadica) is somewhat smaller than the gluteal, but looks rather more like the continuation of the hypogastric. It descends between the rectum and the pyriformis muscle, and issues under the lower margin of the latter, out of the pelvis, being there placed in front of the sciatic nerve. It goes downwards on the back of the thigh, between the trochanter major and the tuberosity of the ischium, being at the internal edge of the sciatic nerve, and on the posterior face of the small rotator mus- cles of the thigh. It sends off in the pelvis the internal Pudic Artery, and also some inconstant branches, of small size, to the viscera within the pelvis; when it has emerged from the latter, it detaches some considerable branches to the origin and to the inferior margin of the gluteus magnus muscle, and to the small rotator muscles. The branch which may be considered as the continued trunk of the ischiatic, descending on the posterior face of the thigh, along with the sciatic nerve, under the hamstring muscles, is lost in ramifications to them, and by anastomoses with the perforating arteries. The Internal Pudic Artery, (Arteria Pudica Interna,) though a branch of the ischiatic, is only in a slight degree smaller. It arises a little above the spinous process of the ischium, in the pelvis, in front of the sciatic plexus, and getting from the pelvis between the INTERNAL ILIAC ARTERY, AND ITS BRANCHES. 25T anterior sacro-sciatic ligament and the inferior margin of the pyri- formis muscle, it passes over the posterior face of the anterior sacro-sciatic ligament, at the spinous process of the ischium. It immediately afterwards returns into the cavity of the pelvis, be- tween the two sacro-sciatic ligaments, at the place where the obturator internus muscle winds over the ischium; it then goes along the internal face of the latter bone and of its ascending ramus, at the inferior margin of the obturator internus muscle: and continues on the internal face of the ramus of the pubes, be- tween the two laminae of the triangular ligament, above the crus of the penis to the symphysis of the pubes. In this course the Internal Pudic Artery detaches several impor- tant branches, in the following order:— a. A ramification along the inferior margin of the pyriformis, to this muscle and to the parts on the posterior face of the neck of the os femoris, where it anastomoses with the other arteries of this region. b. The Lower Haemorrhoidal Artery (Art. Hamorrhoidea Infe- rior Externa) to the inferior part of the rectum, and to the external sphincter ani muscle. This artery arises after the internal pudic has returned within the pelvis, and consists sometimes in several branches. c. The Perineal Artery (Art. Perinea, Transversa Perinei) has its root near the origin of the transversus perinei muscle, and ad- vancing obliquely forwards is distributed in several ramifications to the muscles and integuments of the perineum, and to the poste- rior part of the scrotum. It is unavoidably cut in the lateral ope- ration for the stone. In the female it goes to the sphincter vaginae and to the labium externum. d. When the internal pudic has got beyond the transversus perinei muscle near the beginning of the crus penis, it detaches to the bulb of the urethra, along the posterior margin of the triangular ligament, a branch which penetrates to the corpus spongiosum, and is minutely distributed upon it, some of its ramifications reach- ing to the corpus cavernosum. This branch is called by M. Chaussier, Urethro-bulbar, and instead of being always distinct, it on some occasions comes from the Perineal. e. At the under part of the symphysis pubis, between it and the back of the penis, the internal pudic sends forwards, on the dorsum of the penis, a superficial branch, (Ramus Superficialis Dorsi Vol. II.—23 258 CIRCULATORY SYSTEM. Penis.) It advances to the end of the penis, under the skin, being parallel with its fellow of the other side, and near to it: sometimes the two unite after a short course. They are dispersed in branches to the integuments, and to the elastic ligament of the penis. f. The Cavernous Artery of the Penis (Art. Cavernosa Profunda Penis may be considered as the terminating trunk of the internal pudic. It penetrates the corpus cavernosum, beneath the sym- physis of the pubes, and quickly divides into many ramifications. The latter advance, and continue to subdivide upon the cells of the corpus cavernosum, to which they are principally distributed: some of them reach the corpus spongiosum urethras, and others anastomose with the corresponding arteries of the other side. SECT. VIII.—OF THE EXTERNAL ILIAC ARTERY, AND ITS BRANCHES. The External Iliac Artery (Arteria Iliaca Externa) extends from the bifurcation of the primitive iliac to Poupart's ligament, where it is continued to the lower extremity under the name of the femoral artery. It looks like the continuation of the primitive iliac, and descends at the superior strait of the pelvis along the in- ternal margin of the psoas magnus muscle. In the early part of its course, it is anterior to the external iliac vein; it then, as it approaches Poupart's ligament, gets to its outer margin. It is covered by the peritoneum in front. Where it passes beneath Poupart's ligament to the thigh, it is about half way between the anterior superior spinous process of the ilium and the symphysis pubis, having the vein at its pubic margin and the anterior crural nerve, half an inch from its iliac margin. No branches of conse- quence arise before it reaches the crural arch; it then sends off two, the Epigastric and the Circumflex Iliac Artery. The Epigastric Artery (Arteria Epigastrica) arises somewhat above the crural arch, at the line where the peritoneum is reflected from the fascia transversalis upon the iliac fascia. It at first passes horizontally inwards, then rises obliquely upwards and in- wards, behind the spermatic chord, at the pubic margin of the internal abdominal ring. Afterwards it reaches the external mar- gin of the rectus abdominis muscle, two or three inches above the EXTERNAL ILIAC ARTERY, AND ITS BRANCHES. 259 pubes: ascending along it for a short distance, it then passes to its posterior face, and continues ascending above the umbilicus; where being divided into several branches, it terminates by anas- tomosing with the lower ramifications of the internal mammary artery. This artery is almost entirely spent upon the anterior parietes of the abdomen, in ramifications, which anastomose with the last intercostal and with the lumbar arteries. One of its small twigs, called the External Spermatic artery, following the course of the spermatic chord, or of the round ligament, is distributed upon the cremaster, the tunica vaginalis, and the scrotum of the male, and upon the mons veneris of the female. In some cases the epigastric gives off the obturator artery as stated. The Circumflex Iliac Artery {Arteria Circumflexa Ilii) is of the same size with the epigastric, and comes from the external iliac, sometimes on a level with it, and on other occasions lower down, even below the crural arch. It ascends outwardly towards the anterior superior spinous process of the ilium, along the posterior margin of the crural arch, and following afterwards the direction of the crista of the ilium, it anastomoses with the corresponding branch of the ilio-lumbar artery. The following branches come from it. In the early part of its course some important twigs are sent to the adjacent muscles, as the sartorius, iliacus internus, and so on. At the anterior superior spinous process, it divides into two branches; the smaller ascends between the internal oblique and the transversalis muscle, and is distributed upon them; the other branch which is the continuation of the main trunk along the crista of the ilium at the margin of the iliacus internus muscle, sends ramifications to the latter, and also to the posterior part of the broad muscles of the abdomen, where it anastomoses with the other arteries of this region. Of the Femoral Artery. The Femoral Artery (Arteria Femoralis, Cruralis,) the continu- ation of the external iliac, extends from the crural arch or Poupart's ligament, to a perforation for its passage through the adductor mag- nus muscle, and which is commonly one-third of the whole length of the os femoris, above the knee joint. This great trunk, imme- 260 CIRCULATORY SYSTEM. diately below Poupart's ligament is very superficial, and may be felt pulsating where it passes over the pubes. It is there covered only by the common integuments, and the fascia femoris, which is thin; it is bounded internally by the femoral vein, externally by the crural nerve; is half-way between the anterior superior spinous process and the symphysis of the pubes, and lies upon the internal face of the psoas magnus over the interstice between it and the pectineus. In the upper third of its course the femoral artery is at the inner edge of the rectus femoris, and at a short distance from it; it then inclines inwards, and occupies the angle formed by the adhesion of the vastus internus to the adductor longus. The sar- torius, at first, is remote at its outside, but this muscle inclining inwards in its descent gets to the exterior margin of the artery, and afterwards covers it completely for the remainder of its course. The femoral artery is in front of the femoral vein when it has de- scended three or four inches below the crural arch; behind the two is the arteria profunda. When the femoral artery and vein reach the angle formed by the vastus internus and the adductor longus, they are covered by a strong interlacement of tendinous fibres from these muscles. The femoral artery sends off these branches: 1. The Superficial Artery of the Abdomen (Art. ad Cutem Ab- dominis) is small, and arises at the lower margin of Poupart's liga- ment : it goes upwards towards the umbilicus, beneath the fascia superficialis abdominis, and is distributed to the integuments of this region. One of its ramifications goes to the inguinal glands. 2. The External Pudic Arteries (Art. Pudenda Externa) come from the femoral at the same point, and are two or three in num- ber; they are of small size. One of them inclines inwards along the groin, between the skin and the fascia femoris, and is distri- buted to the integuments of the pubes, to those of the penis, and to the scrotum, or to the labium externum of the female. The se- cond, and the third when it exists, are rather lower down, and are dispersed upon much the same region by branches to the integu- ments. The lymphatic glands of the groin also derive their supply of blood from these several external pudic arteries. 3. The Profound Artery, (Arteria Profunda Femoris,) the great FEMORAL ARTERY, AND ITS BRANCHES. 261 muscular artery of the thigh, is but slightly inferior in size to the femoral itself, and comes from the latter at the distance of from one to two inches below the crural arch. It lies behind the femo- ral artery, and descends in that situation between the insertion of the adductor brevis and the vastus internus muscle, to the upper part of the insertion of the adductor longus. In this course its size is much diminished by the origin from it of several considerable trunks as follows: a. The External Circumflex, (Arteria Circumflexa Externa,) though most frequently a branch of the profunda, sometimes comes from the femoral above or below it a short distance. It goes im- mediately outwards between the rectus femoris muscle and the cruralis, giving off some inconsiderable ramifications. While be- tween these muscles it divides into two branches, one of which ascends and the other descends; the former is distributed to the anterior margin of the gluteus medius and minimus, to the capsule of the joint, the parts about the trochanter major, and anastomoses with the gluteal and the ischiatic. It is said by Meckel, that these anastomoses have been found much dilated where the external iliac artery has been taken up. The descending branch is about the size of a crow quill, or even larger;.it first passes obliquely downwards between the rectus femoris and the cruralis, it then descends vertically under the anterior margin of the vastus exter- nus, between it and the cruralis, to terminate at the knee, where it becomes superficial and anastomoses with the articular arteries. It is, however, principally distributed to the vastus externus and to the cruralis. b. The Internal Circumflex Artery (Arteria Circumflexa In- terna,) arises from the profunda, near the external circumflex, generally below it, but sometimes the reverse; in some cases, it comes from the femoral artery itself, near the crural arch. It passes transversely inwards, and dips into the interstice between the pectineus and the psoas magnus, after having given off some small twigs to the heads of the adjoining adductors. It then winds under the neck of the os femoris and divides into two branches; the upper one goes to the capsular ligament of the joint, to the obturator externus muscle, anastomoses with the obturator artery, and sends a branch behind the adductor brevis to the upper part of the adductor magnus: the inferior branch is larger than the other; it descends behind the adductor magnus and is distributed 23* 262 CIRCULATORY SYSTEM. in branches to it, to the gracilis, and to the hamstring muscles, sending upwards some ramifications (rami trochanterici) to the parts about the trochanter major, where they anastomose with the external circumflex artery. c. Muscular branches of inconstant origin, and of inconsidera- ble size, are sent from the profunda to supply the anterior face of the adductor muscles. d. The Perforating Arteries (Rami Profundi P erf or antes) obtain the name from their perforating the adductor magnus, which they do near the linea aspera, so as to get to the back of the thigh. They commonly are four in number, and as they come off suc- cessively from the profunda, they are designated numerically. In some cases, however, they are reduced to one, by being concen- trated in a common trunk, which, penetrating high up the adductor magnus, and afterwards descending on its posterior face, is dis- persed upon the muscles on the back of the thigh. The First Perforating Artery arises somewhat below the tro- chanter minor, and penetrates the adductor magnus a little below its superior margin. One of its branches ascends towards the tro- chanter major, where it anastomoses with the external circumflex and with the gluteal, while another descending is spent upon the heads of the flexor muscles of the leg. The Second Perforating Artery gets to the back of the thigh, at the lower margin of the insertion of the gluteus magnus into the linea aspera, being distributed in that region, and to the correspond- ing portion of the long head of the biceps flexor cruris. The Third Perforating Artery penetrates the Adductor magnus somewhat below the commencement of the short head of the biceps, and is dispersed upon the adductor and the adjacent portion of the flexor muscles. The Fourth Perforating Artery penetrates the insertion of the adductor magnus an inch and a half above the opening in it, for the femoral artery; it, in the same way, supplies the posterior face of the adductor and the adjacent muscles. As a summary, it will be readily understood that the profunda is, in this way, through the external and the internal circumflex, and through the perforating arteries, distributed upon all the large muscles of the thigh. POPLITEAL ARTERY, AND ITS BRANCHES. 263 After the origin of the profunda, the Femoral Artery gives off, at different points of its course to the opening of the adductor mag- nus, several twigs the size of a large knitting needle; which go to the sartorius, the gracilis, the adductors and the extensors on the front of the thigh; but they are too inconstant to require a more particular description. The Anastomosing Artery (Arteria Anastomotica) is the last branch of the femoral, and arises just before it perforates the ad- ductor magnus. It descends to the knee, in front of the tendon of the latter, concealed by the internal margin of the vastus internus muscle. It sends off many small twigs to the adjacent muscles, and terminates below by anastomosing with the internal articular arte- ries. It is about the size of a crow-quill. The Popliteal Artery (Arteria Poplitaea) is the continuation of the femoral, after the latter has passed through the tendinous in- sertion of the adductor magnus; and extends from this point to the opening in the interosseous ligament of the leg, just below the head of the tibia. It, first of all, passes from the internal margin of the os femoris, to the notch between the condyles; being there placed in the middle between the internal and the external ham- string muscles, and surrounded by a mass of adipose matter which fills up the hollow of the ham. It is in contact, anteriorly, with the knee joint, and a little below the latter with the popliteus mus- cle, descending there between the heads of the gastrocnemius. It is covered, in the greater part of its extent, posteriorly, by the popliteal vein, and by the sciatic nerve, the latter being more superficial than the'vein. The popliteal artery sends off some small branches to the ham- string muscles, and to the parts contained between the latter, which are too irregular and inconstant for description. The following arteries, also, come from it:— 1. The Superior Internal Articular Artery (Art. Articularis Superior Interna) arises at or above the internal condyle, and fre- quently consists in two trunks. It- passes through the tendon of the adductor magnus, just above the condyle; it then begins to distribute itself in branches, some of which are spent upon the 264 CIRCULATING SYSTEM. lower part of the vastus internus muscle, and others upon the supe- rior internal part of the knee joint. 2. The Superior External Articulating Artery (Art. Articularis Superior Externa) arises from the popliteal, somewhat above the external condyle of the os femoris. It winds, horizontally, above the external condyle, around the bone, between it and the lower part of the biceps flexor cruris, and is then distributed, also, in two orders of branches, some of which supply the lower part of the vastus externus muscle, and others the superior external por- tion of the knee joint. 3. The Middle Articular Artery (Art. Articularis Media) is smaller than either of the above, and sometimes comes from one of them, but generally from the popliteal, on a line with the articu- lation of the knee. It is distributed to the posterior part of the capsular ligament, to the crucial ligaments, and to the correspond- ing adipose matter. 4. The Inferior Internal Articular Artery (Art. Articularis Infe- rior Interna) arises on a line with the inferior part of the internal condyle, sometimes lower down. Its origin is very much con- cealed by the internal head of the gastrocnemius; it passes be- neath the latter, and then between the internal lateral ligament of the knee and the head of the tibia ; consequently, it is covered by the internal hamstring muscles. It afterwards ascends towards the patella, and is distributed in numerous branches to the inferior internal part of the knee joint, and to the adjacent portion of the tibia. 5. The Inferior External Articular Artery (Art. Articularis Inferior Externa) arises near the last, below the external condyle, being concealed by the belly of the plantaris. It passes, horizon- tally, or nearly so, between the popliteus and the outer head of the gastrocnemius, and afterwards beneath the tendon of the biceps and the external lateral ligament of the joint, around the external face of the head of the tibia. It gives small branches to these several parts, and is then distributed, by two orders of ramifica- tions, to the superficial and to the more deeply seated parts at the external inferior portion of the knee joint. ANTERIOR TIBIAL ARTERY, AND ITS BRANCHES. 265 These several articular arteries anastomose freely with each other, and are minutely ramified on the knee joint and the conti- guous structure. They also anastomose with the long descending branch of the external circumflex of the thigh, with the anasto- motica of the femoral, and with the tibial recurrent. 6. The Gastrocnemial Arteries (Arterix Gemellce) are two in number, one for each head of the gastrocnemius. They arise commonly between the superior and the inferior articular arteries, and are about the same size. They penetrate into the muscle, and supply it with blood, terminating their course near the lower part of its bellies. Moreover, some small branches, which go to the contiguous muscles, are frequently observed here; also, the nutritious artery of the tibia. But^heir number and condition are very inconstant. Near the head of the fibula, branches go from the popliteal artery to the upper end of the soleus muscle. Generally, on a level with the aperture in the upper part of the interosseous ligament, but sometimes an inch or two higher up, the popliteal artery terminates by dividing into two large trunks, the Anterior and the Posterior Tibial. The Anterior Tibial Artery (Art. Tibialis Anterior) passes forwards through the foramen of the interosseous ligament, just below.the head of the fibula, and runs down the front of the leg and foot, as far as the base of the metatarsal bone of the great toe. In this course, its relative situation is as follows: It rests upon the front of the interosseous ligament of the leg, on a line drawn from the middle anterior part of the head of the fibula to the middle of the ankle joint. Superiorly, it is bounded on the tibial side by the tibialis anticus muscle, and on the other by the extensor longus digitorum : lower down on the leg, the place of the latter is supplied by the extensor pollicis pedis. Somewhat above the ankle joint the artery, leaving the interosseous ligament, rests upon the front of the tibia, and then gets to the top of the foot, between the joint and the annular ligament. Under the liga- ment it is crossed by the tendon of the extensor pollicis, which gets to its inner side, and afterwards continues so. The anterior tibial nerve adheres to it, in its whole length. The following branches come from the anterior tibial artery: 266 CIRCULATORY SYSTEM. 1. The Recurrent Tibial (Art. Tibialis Recurrens) ascends through the upper extremity of the tibialis anticus muscle, having come off from the anterior tibial immediately upon the latter get- ting to the front of the leg. Several small ramifications pass from it to the heads of the contiguous muscles on the tibia, and to the lower part of the knee joint, where it anastomoses with the lower articular arteries of the knee. 2. Several small arterial twigs are afterwards sent to the mus- cles and to the periosteum of the leg, as the anterior tibial descends; but they are too inconstant in size and position to require descrip. tion. 3. The Internal Malleolar Artery (Art. Malleolaris Interna) arises from the anterior tibial, an inch or two above the ankle joint. It descends, inwardly, between the tibia and the tendon of the tibialis anticus, and, having gained the internal malleolus, is distributed by branches upon it and upon the adjacent portion of the articulation. 4. The External Malleolar Artery (Art. Malleolaris Externa) consists most commonly in two arterial twigs of small size, but frequently in one only. It arises in front of the ankle joint, and going outwardly between it and the tendons of the extensor digi- torum longus, is spent upon the external face of the articulation, where it inosculates with the peroneal artery. This artery is sometimes of considerable size, in which case it also supplies the outer part of the tarsus, and is a substitute for the next. 5. The Tarsal Artery (Arteria Tarsea) arises from the ante- rior tibial, somewhat below the ankle joint near the scaphoides, and, going outwardly beneath the extensor brevis digitorum mus- cle, it is distributed in branches near the external ankle, and upon the outer upper surface of the tarsus. It anastomoses with the external malleolar, with the external plantar, and with the meta- tarsal artery. Some small branches also pass from the anterior tibial at this point to the upper internal face of the tarsus. POSTERIOR TIBIAL ARTERY. 267 6. The Metatarsal Artery (Art. Metatarsea) arises just below the last. It is directed forwards and outwards beneath the exten- sor brevis muscle, and forms a sort of arch at the roots of the metatarsal bones. It furnishes several ramifications to the upper surface of the tarsus and the contiguous parts; amongst them is an interosseal artery for each of the three outer interosseal spaces. These arteries communicate, by small anastomoses, with the arte- ries of the sole of the foot, both at the bases and at the ends of the metatarsal bones, and terminate in front by supplying the backs of the small toes. This artery is sometimes a branch of the tarsal 7. The Dorsal Artery of the Great Toe (Art. Dorsalis Hallucis) arises from the anterior tibial at the root of the first metatarsal bone. It runs along the superior face of the first metatarsal inter- val, and having reached the anterior end of it, divides into two branches, one of which goes to the back of the great toe and the other to the tibial margin of the next toe. The Anterior Tibial, in its course from the ankle joint to the base of the first metatarsal bone, is sometimes called Pedal (Ar- teria Pedioza;) at the posterior end of the first metatarsal inter- val, being still of considerable size, it sinks down to the sole of the foot, and joins itself to the external plantar artery at this point. It frequently happens that the anterior tibial being small in its course down the leg, is joined by the continued trunk of the pero- neal, which perforates the interosseous ligament somewhat above the ankle joint. Afterwards the trunk formed by this union, being of considerable size, follows the course and has the distribution mentioned. The Posterior Tibial Artery (Arteria Tibialis Postica) is some- times called, at its commencement, till it gives off the peroneal, tibio-peroneal; it extends from the head of the tibia to the sinuosity of the os calcis, in a line from the middle of the ham to the internal ankle. It is at the tibial side of the back of the leg, on the poste- rior face of the flexor longus digitorum muscle; and covered by the fascia of the latter. In the two superior thirds of its course, it is concealed behind by the gastrocnemius and the solaeus muscle: in the inferior third, it is at the internal margin of the tendo- achillis. At the ankle joint, before it passes into the sinuosity of 268 CIRCULATORY SYSTEM. the os calcis, it is between the tendon of the tibialis posticus and that of the flexor longus pollicis pedis, being covered by the laci- niated ligament. It is accompanied, at its external margin, by the posterior tibial nerve. The posterior tibial artery is distributed after the following manner: 1. The Peroneal Artery (Arteria Peronea) is its first branch of any importance, and is but little smaller than the continued trunk. It arises an inch or two below the origin of the anterior tibial, and extends, on the posterior face of the leg, to the external ankle. It is, in some measure, concealed by the posterior side of the fibula, being placed there between the origin of the flexor longus pollicis muscle and the external edge of the tibialis posticus. It is covered behind by the flexor longus pollicis, by the soleus, and by the gas- trocnemius ; it is, therefore, deep and of extremely difficult access in the living body. In this course, it sends small branches to the gastrocnemius, to the soleus, and to the other contiguous muscles on the back of the leg. After having descended two-thirds of the length of the fibula, it divides into an anterior and a posterior branch. The former traverses the interosseous ligament, and descending in front of it, covered by the muscles which arise from the lower part of the fibula, is, distributed upon the upper external part of the foot near the ankle joint. The posterior branch continues in the primitive course of the peroneal artery at the internal posterior margin of the fibula, and descending behind the tibio-peroneal articulation, reaches the external face of the os calcis: it detaches several small ramifications to the contiguous muscles; and, upon the os calcis, is divided into twigs which supply the adjacent parts and the in- teguments below the external ankle. 2. In the descent of the posterior tibial artery to the hollow of the os calcis, it detaches several small muscular branches, princi- pally to the tibialis posticus, and to the flexors of the toes. One twig, which is the nutritious artery of the tibia, comes from its upper part when not furnished from the popliteal artery, and enters the foramen on the posterior surface of the bone. While the posterior tibial is in the hollow of the os calcis, be- tween it and the abductor muscle of the great toe, it furnishes some POSTERIOR TIBIAL ARTERY, AND ITS BRANCHES. 269 small twigs to the contiguous muscles, and to the integuments of the sole of the foot; it then divides into two branches, the Internal and the External Plantar Artery. The Internal Plantar Artery (Art. Plantaris Interna) is much smaller than the other. It advances between the abductor pollicis pedis and the internal inferior margin of the bones of the foot, and terminates at the anterior end of the first metatarsal bone, by join- ing the internal digital artery of the great toe. In this course, it sends, continually, small ramifications to the muscles of the great toe and to the flexor brevis digitorum pedis. One of the largest of these ramifications comes off near the os scaphoides, and cruises along the internal margin of the abductor pollicis to its anterior end ; another becomes superficial on the sole of the foot, between the abductor pollicis and the flexor brevis digitorum, and goes for- ward as far as the other. The External Plantar Artery (Art. Plantaris Externa) is the continuation of the posterior tibial, and diverges from the internal plantar towards the outer margin of the sole of the foot, between the flexor brevis digitorum pedis and the flexor accessorius. Having reached the internal margin of the abductor minimi digiti, it advances along the latter to the base of the metatarsal bone of the fourth toe; it then makes a curvature forwards and inwards across the metatarsal bones, between the tendons of the flexor longus digitorum and the interosseous muscles, to the first meta- tarsal interval, where it is joined by the anterior tibial artery from above. This curvature is the Arcus Plantaris, of which the con- cavity is behind and inwards. The external plantar artery is distributed as follows:— Shortly after its origin, it detaches a branch which goes back- wards and outwards, and which, keeping close to the os calcis in front of its tuberosity, is distributed to the heads of the muscles arising from it, and to the outer surface of the heel; it also sends an arteriole along the external edge of the abductor minimi digiti. At the base of the fourth metatarsal bone, arises a branch called the External Digital Artery of the Little Toe. It goes at first deeply along the internal margin of the muscles situated on the fifth metatarsal bone, and, afterwards, at the head of the latter, it Vol. II.—24 270 CIRCULATORY SYSTEM. gets between them and the bone, and is distributed along the ex- ternal margin of the little toe. The four Digital Arteries of the foot arise next successively from the arcus plantaris, at or near the metatarsal intervals. They run along the inferior surface of the interosseous muscles, getting to the bases of the first phalanges above the transversalis pedis. Each artery there bifurcates, so as to supply the opposed surfaces of the adjacent toes, in the same way that the digital arteries of the hand are distributed. The digital artery of the first metatarsal interval which comes from the interna] extremity of the arcus plantaris, where the ante- rior tibial artery joins the latter, goes forwards concealed by the flexor brevis of the great toe: just behind the sesamoid bones, it sends a branch which supplies the internal side of the great toe, being its internal digital artery, and anastomoses with the internal plantar artery. What remains of it, is still a trunk of considerable magnitude, which advancing to the space between the first pha- lanx of the great toe and of the toe next to it, there bifurcates, as mentioned, so as to supply the opposite sides of these two toes. The Perforating Arteries, as they are called, are of two kinds, the anterior and the posterior. The former arise from the con- vexity of the plantar arch, and being destined principally to the interosseous muscles, anastomose at the anterior end of the latter with the branches from the metatarsal artery, which supply their superior surface. The posterior perforating arteries come also from the plantar arch, and penetrating the posterior end of the in- terosseous spaces, anastomose also with the metatarsal arteries on the dorsum of the foot. The preceding trunks of the internal and of the external plantar arteries are the principal ones which are found in the bottom of the foot, but from them there arise an immense number of arte- rioles; which, descending vertically between the interstices of the muscles and of the aponeurosis plantaris, supply the adipose matter and the skin of the sole of the foot, so as to render them extremely vascular. OF THE VEINS. 271 CHAPTER III. Of the Veins. The veins of the body, assembling from different points, unite successively into the ascending and into the descending vena cava, which discharge their blood into the right auricle of the heart. The veins of the head, of the upper extremities, and of the thorax, run into the descending cava, while the veins of the abdomen and of the lower extremities concur to form the ascending cava. SECT. I.—OF THE VEINS OF THE HEAD AND NECK. Many of these veins are described elsewhere with the encephalon and with the eye, to which accounts the reader is referred. The others are more superficial, and arise as follows: The Facial Vein (Vena Facialis) observes the course of the facial artery, being placed behind the latter. It arises upon the forehead by a considerable number of roots, which unite into a single trunk called the frontal vein. This vein descends from the forehead, over the root of the nose, along the internal canthus of the orbit. It there receives re-enforcements from the eyelids, and anastomoses with the ophthalmic veins; descending afterwards, in the same way with the facial artery, and taking the name of facial vein, it receives successively the veins from the nose, from the outer side of the orbicularis palpebrarum, from the upper and lower lips, and from the muscles and the integuments of the face. It descends to the neck at the anterior margin of the masseter muscle, and is then augmented by the ranine, the submental, and the inferior palatine veins, and immediately afterwards goes into the internal or the external jugular vein. The Ranine Vein (Vena Ranina) arises at the point of the tongue, and then goes along its under surface, where it can be 272 CIRCULATORY SYSTEM. readily seen by turning up the end of the tongue. It joins the facial near the posterior margin of the mylo-hyoideus muscle. The Submental Vein (Vena Submentalis) arises by ramuscles from the sublingual and the submaxillary gland, and from the con- tiguous muscles. It joins the facial vein a little below the last: sometimes it runs into the superior thyroidal vein. The Inferior Palatine Vein (Vena Palatina Inferior) arises prin- cipally from the soft palate and from the tonsil gland, but receives a few twigs from the contiguous parts. It corresponds with the inferior palatine artery, a branch of the dorsal lingual, (Dorsalis Linguae;) and descends the pharynx along side of it, and termi- nates in the trunk of the facial near the last. The Lingual Vein (Vena Lingualis) has its origin from a plexus of veins situated on the root of the tongue under its lining mem- brane, between the epiglottis and the foramen caecum: branches are also sent to it from the muscular structure of the tongue, from the sublingual gland and from the adjacent muscles, and it anasto- moses with the vena ranina. It goes backwards between the hyo- glossus and the mylo-hyoideus muscle, along the superior margin of the os hyoides, and then discharges into the internal jugular vein near the facial. The Pharyngeal Vein (Vena Pharyngea) arises from a plexus of veins belonging to the pharynx, and discharges either into the lingual or into the internal jugular near it. The Superior Thyroid Vein (Vena Thyroidea Superior) corre- sponds with the distribution of the superior thyroid artery, in the origin of its primitive roots. Having collected the latter into one or more trunks, it passes upwards and backwards beneath the sterno-hyoid and thyroid muscles, and discharges itself into the upper part of the internal jugular, or into one of the large branches of the external jugular. The Occipital Vein (Vena Occipitalis) arises from the branches of the occipital artery, and following the course of the latter, be- VEINS OF THE HEAD AND NECK. 273 neath the muscles connected' with the mastoid process of the tem- poral bone, it is discharged into the upper part of the internal jugu- lar or of the external; more rarely into the latter. The Diploic Veins (Venae Diploicas) have been described in the account of the bones of the cranium as situated between the two tables in the diploic structure, and commence by very fine capil- lary tubes from its lining membrane. The one in the frontal bone discharges itself into the frontal vein, that in the occipital bone into the occipital vein, and the two in the parietal bone into the deep temporal veins. They do not open each by one orifice, but by several, which make their terminations not very distinct or abrupt: besides which, they communicate freely by a crowd of ramuscles, with the veins of the scalp on the outside, and with those of the dura mater internally. The Superficial Temporal Vein (Vena Temporalis Superficialis) corresponds with the temporal artery, and takes its rise from the terminating ramifications of the latter. It is immediately below the skin. Its branches communicate freely with each other, and with the branches of the frontal and of the occipital vein: at the zygoma it receives the trunk of the Middle Temporal Vein, which, collecting the blood from the temporal muscle and other parts within the zygoma, perforates the temporal fascia to discharge itself into the superficial temporal vein. The Temporal Vein, (Vena Temporalis,) which is formed by the junction of the Middle and the Superficial Temporal, descends over the root of the zygoma, in company with the artery, and penetrates, like the latter, through the substance of the parotid gland. It is joined, near the neck of the lower jaw, by the internal maxillary vein. It is also joined, in its descent through the paro- tid gland, by the anterior auricular veins, by the parotid veins, and by the transverse facial, all of which correspond with the arteries of the same name. The temporal vein, on issuing from the pa- rotid gland, immediately afterwards becomes the External jugu- lar; but, occasionally, it ends wholly, or in part,, in the Internal jugular. The Internal Maxillary Vein (Vena Maxillaris Interna) is de- 24* 274 CIRCULATORY SYSTEM. rived from the terminating ramifications of all the arteries into which the internal maxillary is divided; it is, therefore, composed of the spheno-palatine vein, which brings the blood from the nose, of the infra-orbital, of the pterygoids, inferior maxillary, deep- seated temporal, and so forth, with the exception of the vein, which might belong to the middle artery of the dura mater, but which does not exist according to Portal and to Hippolytus Cloquet. By the aid of the spheno-palatine vein, the internal maxillary commu- nicates with the sinuses in the bottom of the cranium, by branches, called the Emissary Veins of Santorini,* which pass through the foramen ovale, rotundum, and spinale. It also communicates with the plexus of veins on the side of the pharynx. The External Jugular Vein (Vena Jugularis Externa) is gene- rally the continuation of the temporal. It descends on the neck almost vertically, between the platysma myodes and the sterno- mastoideus, in the direction of the fibres of the first, and crossing those of the latter obliquely. Just behind the clavicle, at the ex- ternal margin of the sterno-mastoideus, it opens into the subclavian vein, in front of the scalenus anticus muscle. Sometimes, instead of one trunk only, there are two or three, which unite at a varia- ble distance above the subclavian. This vein varies also in its size, and in the branches from which it is made up: sometimes it receives the facial vein, and on other occasions the latter runs, as stated, into the internal jugular. The condition and arrangement of the internal and external jugulars are, indeed, so inconstant, in regard to the trunks that compose them, that it is scarcely possible to give more than a very general description of them with tolera- ble accuracy. The external jugular, in going down the neck, anastomoses more or less with the internal jugular, either directly or by its branches: one of these anastomoses is found near the angle of the lower jaw, about the trunk of the facial vein, and is so large as to explain the difference of opinion among anatomists in regard to the latter's termination. Sometimes the occipital vein, or a large trunk from it, joins the external jugular. At the lower part of the neck, the external jugular is augmented by the superficial cervical veins. Some of these come from the lower part of the neck, near Obs. Anat. chap. iii. p. 74. VEINS OF THE HEAD AND NECK. 275 the shoulder, and join the jugular just above the clavicle; others are placed on the lower front part of the neck, above the sternum, and there form with each other a remarkable and an irregular plexus, consisting in numerous meshes. It frequently happens that the external jugulars of the two sides, just before they terminate, anastomose with each other by a large horizontal trunk, which runs just above the end of the sternum, in front of the sterno-mas- toid, sterno-hyoid, and the sterno-thyroid muscles: this trunk, on other occasions, goes more deeply, and behind these muscles, from one subclavian vein to another, or to a jugular; its mode of attach- ment is, indeed, much varied: when it exists, however, it frequently receives several of the superficial veins of the neck, and the infe- rior thyroideal. The Internal Jugular Vein (Vena Jugularis Interna) extends from the basis of the cranium to the internal margin of the first rib, at the insertion of the scalenus anticus muscle. The lateral sinuses of the dura mater, receiving ultimately all the blood of the brain, of the eye, and a portion of that of the nose, convey it from the cranium through the posterior foramina lacera, where they are joined to the upper end of the internal jugular veins, the lining membrane of each sinus being continuous with that of its respec- tive vein. Each vein is somewhat enlarged at its commencement, which is therefore called its Gulf or Sinus; the right vein is fre- quently larger than the left. The internal jugular then descends in front of the transverse processes of the vertebrae of the neck, on the outer side of the internal end of the primitive carotid artery, and of the pneumogastric nerve. It is concealed above by the styloid process of the temporal bone, and the muscles belonging to it; it is crossed, halfway down the neck, by the omo-hyoideus muscle; and,, in the greater part of its course, is beneath, and nearly parallel with the anterior edge of the sterno-mastoideus. Having got behind the sternal end of the clavicle, it is joined at the internal edge of the scalenus anticus by the subclavian vein, and the union of the two forms the vena innominata. The internal jugular receives frequently the large anastomotic branch, just alluded to, from the external jugular, at the under mar- gin of the parotid gland, between the digastric muscle and the lower jaw, and it is in this vicinage that it is generally re-enforced 276 CIRCULATORY SYSTEM. by the Occipital; the Lingual; the Facial; the Pharyngeal; and the Superior Thyroidal Veins, that have been described. The Vena innominata, or Brachio Cephalic Vein, is the trunk formed on either side by the junction of the subclavian with the internal jugular. On the right side it looks like the continuation of the internal jugular, and descends in contact with the right pleura, behind the right side of the sternum, for the distance of an inch or thereabouts. On the left side it crosses behind the superior end of the sternum, descending obliquely in this course, from left to right, until it joins the trunk on the right side. It lies in front of the great vessels proceeding from the arch of the aorta; and is much longer than the trunk of the other side. A common name for it is the Transverse Vein. The Vena Cava Superior, or Descendens, arises from the junction of the two vena? innominatae. It begins between the cartilage of the first rib on the right side, and the arch of the aorta, and descends to the superior posterior part of the right auricle, into which it emp- ties itself. Its course is not entirely vertical, but inclining some- what to the left side and forward. It is about three inches long. The superior third of it is free, and is in contact on the right with the pleura, and on the left with the arteria innominata; the re- maining portion of it is invested by the pericardium, and has the aorta on its left anterior face.* The following venous trunks discharge into the venae innomi- natae, or into the descending cava. The Inferior Thyroidal; the Vertebral; the Superior Intercostal; the Internal Mammary; the Vena Azygos, and some others of smaller size. 1. The Inferior Thyroid Vein (Vena Thyroidea Inferior) arises from the inferior part of the thyroid gland, by many small roots, which anastomose with those of the opposite side. It descends in front of the trachea, involved in the loose cellular and fatty matter lying upon it, and empties itself into the left brachio-cephalic vein, or Transverse Vein. * In some very rare cases there have been two descending venae cavte, one for the right side and the other for the left. J. F. Meckel. VEINS OF THE HEAD AND NECK. 277 There is occasionally another thyroid vein, called the middle, which discharges itself into the lower part of the internal jugular. 2. The Vertebral Vein (Vena Verlebralis) is placed in the same canal with the vertebral artery. At its upper extremity it anasto- moses with the occipital sinus, by a branch lodged in the posterior condyloid foramen. In its descent of the canal of the transverse processes, it communicates at each intervertebral foramen with the vertebral sinuses, and also receives a branch from the muscles of the neck. It issues at the sixth transverse process, and going on the right side behind the subclavian artery, but on the left, in front of it, it is, finally, emptied into the commencement of the vena innominata. 3. The Superior Intercostal Vein (Vena Intercostalis Superior) is on the right side an inconsiderable trunk, sometimes deficient, which commences by branches belonging to the first two intercos- tal spaces, and empties into the vena innominata just below the vertebral. On the left side it is much larger, and arises from the six or eight superior intercostal spaces. It lies on the left side of the bodies of the upper dorsal vertebras, and at each intercostal space, as it ascends, receives its contribution of an intercostal vein, corresponding with the intercostal artery; it also receives branches from the oesophagus, and about the third dorsal vertebra the left bronchial vein is discharged into it. Issuing from the thorax above, it discharges into the left vena innominata near its commence- ment. 4. The Internal Mammary Vein (Vena Mammaria Interna) arises from the terminating branches of the internal mammary ar- tery, and in its situation and course corresponds with the latter. It is re-enforced by small branches from the diaphragm, the pericar- • dium, and the thymus gland. Each internal mammary vein dis- i charges itself on its respective side into the vena innominata near l the superior intercostal. 5. The Vena Azygos is placed in the posterior mediastinum, ( on the right anterior margin of the Dorsal Vertebrae, and dis- i charges itself in making an arch forwards over the root of the 278 CIRCULATORY SYSTEM. right lung, into the descending cava, just above the introduction of the latter into the pericardium. Its orifice there is supplied with a membranous duplicature or valve, which prevents the blood once discharged from re-entering it. The valve is sometimes double, and also somewhat removed from the orifice. It was the observa- tion of these valves, first of all, which called the attention of Syl- vius and of Charles Etienne to their existence in other veins. This vein begins in the abdomen, either by an anastomosis with the ascending cava, or with the upper lumbar vein ; it then ascends into the thorax through the aortic orifice of the diaphragm, and continuing to mount upwards beneath the pleura it lies on the right side of the thoracic duct, and crosses in front of the intercostal arteries of the right side. In this course, it receives from the ten inferior intercostal spaces of the right side, their respective inter- costal veins corresponding in their origin and course with the in- tercostal arteries. About the sixth vertebra of the back, it receives a trunk (Vena Hemiazygos) which is formed from the four or six lower intercostal veins of the left side, and commences in the ab- domen, also, by anastomosis with the left emulgent vein or the left superior lumbar, and which gets into the thorax either through the aortic orifice of the diaphragm, or through a special opening to the left of it. The vena azygos also receives some small ramifica- tions from the oesophagus, and near the fourth dorsal vertebra, the right bronchial vein is discharged into it. Other small ramifica- tions join it from the parietes of the descending cava, of the aorta, and of the right pulmonary artery. Branches also proceed to it, or to the intercostal veins, from the interior of the vertebral canal at each intervertebral foramen. This vein is commonly spoken of by anatomists, as forming a great anastomosis between the ascending and the descending cava. The tendency to establish this anastomosis is strikingly confirmed by a preparation made by myself, when I was a student in this institution, in 1813, and now in the Anatomical Cabinet, where the ; ascending cava, instead of emptying, as usual, into the lower part ; of the right auricle, ascended on the right side of the dorsal verte- ■ ■ brae, and supplanting in situation and office the vena azygos, dis- • • charged itself into the descending cava, in a manner corresponding ; ; with the vena azygos, by making a curvature forwards over the : : root of the right lung. VERTEBRAL SINUSES. 279 The Sinuses of the Vertebral Column* (Sinus Columnae Verte- bralis) are situated in the vertebral cavity, on the posterior face of the bodies of the vertebrae, and in front of the dura mater of the spinal marrow. They are two long veins, one at each margin of the posterior vertebral ligament, and extend from the foramen magnum occipitis to the inferior end of the sacrum. They are maintained in their places by a loose cellular tissue between the bones and the dura mater, and, therefore, unlike the sinuses of the brain, are entirely independent of the dura mater. These sinuses are small where they begin in the sacrum, and are there merely two cylindrical veins surrounded by the loose cellular matter, and which have an anastomosis between them. In ascending the spine they enlarge, but not continually, as they are somewhat smaller in the cervical than in the dorsal vertebrae. On the body of each vertebra they are rather larger than on the intervertebral substance: this gives them a knotted appearance, which is especially distinct in the loins. At the middle of each vertebra they are joined to one another by transverse branches, which pass beneath the posterior vertebral ligament, and receive the veins belonging to the cellular structure of the bone. Externally, they communicate with the vertebral veins in the transverse processes of the neck, with the intercostal, and with the lumbar veins, as an opening occurs between the ad- jacent vertebrae. They also receive many delicate veins from the dura mater of the spine. These two trunks terminate at their upper end by an anastomosis, through the anterior condyloid fora- men, with the internal jugular: they also terminate by anastomosis with the anterior occipital sinus and with the vertebral veins. From the arrangement of these sinuses, it appears that each bone of the spine has its own venous system or circle; which also is the case in regard to the corresponding section of medulla spi- nalis in early life, when it occupies the whole length of the spine. Each of these circles, by the freedom of their anastomoses, there- fore, forms a link in a long chain of venous circles belonging to the structure of the spine. * G. Breschet, Essai sur les Veines du rachis. Paris, 1819. 280 CIRCULATORY SYSTEM. SECT. II.—OF THE VEINS OF THE UPPER EXTREMITIES. The veins of the upper extremities are superficial and deep- seated, and arise from the distribution of the arteries. The Deep-seated Veins are found in company with each arte- rial ramification, there being two veins to one artery generally. We thus have them observing the course of the arteries of the hand, of the fore-arm, of the arm, and of the shoulder. At the bend of the arm, the two radial and the two ulnar veins coalesce into the two brachial veins, which attend the brachial artery, one on each of its sides, and at intervals throw anastomotic branches across it. Sometimes, but one of these trunks exists, with the ex- ception of the lower part of the arm, where there are most com- monly two. The trunk (or trunks, as the case may be,) is joined by the basilic vein, at a point varying from the middle of the arm to the axilla. These venae comites, or satellites, are invariably called after the arteries which they attend, and having no diffe- rence from the latter in relative situation, a farther description of them may be dispensed with. The Superficial Veins lie between the skin and the brachial aponeurosis, and are considerably larger than the preceding. Their earliest roots are seen on the back of the fingers; they then appear on the back of the hand, on the posterior of the lower end of each interosseous space. There are commonly six trunks in all: the one on the ulnar side of the hand, and the three next to it, converge towards the middle of the back of the carpus into a single trunk; the two others, one of which comes from the thumb and the other from the back of the fore-finger, converge to the outer end of the carpus, and there form a single trunk also. Be- tween these several trunks, there are frequent anastomoses, and they, finally, assemble into two principal branches called the Ce- phalic and the Basilic Vein. The Cephalic Vein (Vena Cephalica, Radialis Cutanea) is the trunk which comes from the thumb and from the fore-finger, and has at first the name of Cephalica Pollicis. It ranges along the anterior and radial margin of the fore-arm, and receives, conti- nually, an augmentation from small collateral branches on the VEINS OF THE UPPER EXTREMITIES. 281 back of the fore-arm. Having reached the bend of the arm, it then ascends along the external margin of the biceps flexor cubiti till it touches the lower margin of the pectoralis major muscle; it then rises superficially along the interstice between this muscle and the deltoid, to within eight or ten lines of the clavicle, where it dips down to join the axillary vein. Along the arm, it receives some small secondary cutaneous branches. The Basilic Vein (Vena Basilica, Cubitalis Cutanea) is larger than the cephalic, and begins by the trunk which comes from the ulnar side of the back of the hand, and is first called the Vena Salvatella. On the fore-arm, the basilic frequently consists in two long trunks, the anterior and the posterior; in this case, the poste- rior is the principal one, and runs along the internal posterior edge of the ulna until it comes to the bend of the arm; it then mounts over the latter, rising obliquely in front of the internal condyle. The anterior branch begins near the palm of the hand, runs up in front of the ulnar side of the fore-arm, and discharges itself into the median basilic vein over the brachial artery in front of the bend of the arm. These two trunks, or one as the case may be, receive the cutaneous veins belonging to the ulnar side of the fore-arm. Above the elbow joint, the basilic gets below the fascia of the arm at the inner edge of the biceps, and about the middle of the arm becomes, by its junction with the venae satellites, the Brachial Vein; but sometimes, as mentioned, this junction occurs much higher up. The Median Vein (Vena Mediana) arises, by branches, from the wrist, from the palm of the hand, and from the middle of the front of the fore-arm. It forms a trunk which ascends in front of the fore-arm, and which, a few inches below the bend of the arm, divides into two. One branch runs outwardly, in ascending for an inch or two, and joins, at the outer side of the bend of the arm, the cephalic vein; it is called, therefore, the Median Cephalic. The other branch continues to ascend, and, crossing obliquely the direction of the brachial artery, it receives, near the latter, the anterior trunk of the basilic vein, and somewhat above the bend of the arm, runs into the proper basilic vein: it is called the Median Basilic. Vol. II.—25 282 CIRCULATORY SYSTEM. There is frequently a departure from the [(receding arrangement of the median vein; the most common is where a trunk begins from the cephalic, below the bend of the arm, and runs obliquely in front of the latter to join the main trunk of the basilic above the elbow joint. This oblique trunk stands in the place of median cephalic and median basilic, and receives successively the median, the anterior, and the posterior basilic. It is frequently the median itself, and has a short anastomosis, in such case, with the cephalic vein. The Superficial Veins anastomose frequently with each other, so that, when they are all fully injected, a plexus of veins is found immediately beneath the skin of the upper extremity from one end to the other. The Venae Satellites also anastomose frequently by branches which cross the artery to which they belong. At the bend of the arm, at the wrist, and in different places, there are also anastomoses between the deep-seated and the superficial veins. The Axillary Vein (Vena Axillaris) results from the union of the basilic with the brachial vein. It is below and in front of the axillary artery, being included in the same sheath with it, and also involved with the axillary plexus of nerves. It retains its name from the lower margin of the arm-pit to the under surface of the clavicle, where, like the artery, it is then called subclavian. In this course it is joined near the points where the corresponding arteries are given off, by the Anterior and the Posterior Circumflex Vein; by the Scapular; and by the External Thoracics. The Subclavian Vein (Vena Subclavia) extends from the termi- nation of the axillary to the vena innominata, where the latter is constituted by the junction of the internal jugular with the subcla- vian. In its course it goes under the subclavian muscle, and is in front of the subclavian artery from the beginning, but near it: afterwards it is separated from the artery by the latter going be- tween the anterior and the middle scalenus muscle ; whereas the vein runs over the anterior end of the first rib, in front of the inser- tion of the scalenus anticus. The Subclavian Vein is joined by some branches coming from the shoulder and from the lower part of the neck; and, at the VEINS OF THE LOWER EXTREMITIES. 283 outer margin of the origin of the sterno-mastoid muscle, it is aug- mented by the addition to it of the external jugular. It terminates at the internal margin of the scalenus anticus, as mentioned in the vena innominata. SECT. III.—VEINS OF THE LOWER EXTREMITIES. The veins of the lower extremities, like those of the upper, are deep-seated and superficial. The former follow the course of the arteries, and are the venae satellites ; there being, for the most part, two veins for every artery as far up as the ham, and also as re- gards the muscular branches of the thigh. These venae satellites adhere closely to the artery, and are separated from each other by the latter. They also have frequent anastomoses with each other across the artery. The Popliteal Vein (Vena Poplitea) is a single trunk formed by the union of the anterior tibial, the posterior tibial, and the pero- neal veins. It begins on the posterior part of the head of the tibia, and extends upwards through the ham to the perforation in the adductor magnus muscle, which transmits the femoral artery. It is situated on the posterior face of the popliteal artery, to which it closely adheres; and behind it is the popliteal nerve, the continua- tion of the great sciatic. The Femoral Vein (Vena Femoralis) is the continuation up- wards of the popliteal: it at first is placed behind the artery, but in a short space it gets to its interior face, and continues to adhere to it, in that situation, up to Poupart's ligament, where it becomes the external iliac vein. At the usual distance below the groin, where the arteria profunda is given off, the femoral vein receives the vena cruralis profunda, which is derived from the branches of this artery, and is rather more superficial than it; the two, how- ever, adhere closely together. Just below Poupart's ligament the femoral vein receives several small branches of veins corresponding with the external pudic arteries. The Small Saphena (Vena Saphena Minor, Externa) com- mences by several small branches near the external side of the 284 CIRCULATORY SYSTEM. top of the foot, and the external ankle; a trunk is formed by them behind the latter, which ascends along the tendo-achillis and the posterior face of the gastrocnemius muscle, collecting several small veins from the back of the leg in its course. This vein is super- ficial in its whole length, being placed immediately beneath the skin. In the ham, it goes for a short distance along the internal face of the popliteal nerve, and then makes a dip through the adi- pose matter there to empty into the popliteal vein. It is said, by Portal, that the branches of this vein become very apparent in persons who suffer from podagra, and from enlarge- ments of the lymphatic glands in the ham. In such case, their distention has been relieved by the application of leeches along them. The Great Saphena (Vena Saphena Magna, Interna) is also superficial, has its primitive roots coming from the internal upper part of the foot, and from the sole of the latter. These branches are assembled into a trunk which passes upwards in front of the internal ankle, then ascends along the internal face of the leg, in a line corresponding with the posterior margin of the tibia. The great saphena continues its ascent over the internal condyle near its posterior part, and then mounts up the internal face of the thigh, in a line corresponding nearly with the internal margin of the sar- torius muscle. It finally terminates in the femoral vein, about twelve or eighteen lines below Poupart's ligament, an opening being left in the fascia femoris for this purpose. In the whole of this course the great saphena is situated between the skin and the fascia of the lower extiemity; it is, consequently, so superficial, that in persons of moderate corpulency it is very visible, and by slight pressure above, along with the erect position, it becomes so much swollen, that it is easily opened with the lancet where it passes over the internal ankle. It receives, in its ascent, small branches from the anterior and posterior part of the leg, from the corresponding surfaces of the thigh, and near its termination it gets a few of the external pudendal veins. When the great and the small saphena veins are successfully injected, their branches are seen to form a considerable number of anastomoses, which thereby produce a remarkable venous net- work, just beneath the skin of the whole inferior extremity. VEINS OF THE ABDOMEN. 285 SECT. IV.—VEINS OF THE ABDOMEN. The External Iliac Vein, (Vena Iliaca Externa,) being the con- tinuation of the femoral vein, passes into the abdomen, under Pou- part's ligament, and in contact with the internal margin of the external iliac artery. It there receives the epigastric, and the circumflex iliac veins, corresponding with the arteries of the same name; it also receives a vein of some size, which enters by the ab- dominal canal in adhering to the spermatic chord, and which comes from the coats of the testicle.* It keeps then along the internal side of the artery, somewhat behind it, at the superior margin of the pelvis, and joins the hypogastric vein opposite to the sacro-iliac junction, and thereby forms the common iliac vein. The Hypogastric Vein (Vena Hypogastrica, Iliaca Interna,) comes from the inferior part of the pelvis in front of the sacro-iliac junction, and in company with the hypogastric artery. It arises by branches corresponding with the distribution of the latter to the viscera of the pelvis, and to its external parts; these branches are so numerous at particular points, and have such frequent anasto- moses, that they are formed into a Plexus. Thus, there is a hemor- rhoidal plexus for the lower part of the rectum, a vesical for the bladder, a sacral for the sacrum, a pudendal for the parts of gene- ration in the male, a vaginal for the vagina, and a uterine for the uterus of the female. The Plexus Hemorrhoidalis, besides being connected with the hypogastric, also anastomoses with the branches of the vena por- tarum. The Plexus Vesicalis is different in the two sexes. In man it commences at the extremity of the penis by several branches, which unite into two trunks of considerable size, the Venae Dor- sales Penis.f The latter go along the upper face of the penis, near or at its middle, to the symphysis of the pubes, continually re- ceiving in this course small trunks- from the integuments of the penis and from the scrotum. They then get into the pelvis be- tween the root of the penis and the symphysis pubis, and continue * H. Cloquet, Traite D'Anat. t They are frequently found to unite into a single trunk,.called, in such case, the- Vena Magna Ipsius Penis. 25* 286 CIRCULATORY SYSTEM. horizontally backwards on the side of the prostate gland, of the vesiculae seminales, and of the lower fundus of the bladder. They receive many branches from these parts, which, with the frequency of the anastomoses about here, constitute the vesical plexus. The ktter, finally, discharges into the lower part of the hypogastric vein by two or more branches. In the female the vesical plexus begins on the dorsum of the cli- toris, by several branches coming from it and from the vulva; they get into the pelvis under the symphysis pubis, and on the sides of the urethra and of the vagina, forming upon the lower part of the bladder, and on the side of the vagina, with the assist- ance of branches from these viscera, a remarkable plexus, which also empties into the internal iliac vein. The Plexus Sacralis consists in an order of veins, anastomosing freely with each other, and corresponding with the middle and the lateral sacral veins. They communicate with the inferior end of the vertebral sinuses through the anterior sacral foramina; they also communicate with the hemorrhoidal and with the vesical veins. They terminate in the venous trunks, nearest the, origin of the ar- teries from which they are derived. The Plexus Pudendalis is derived from the branches of the inter- nal pudic vein which go to the perineum, to the posterior part of the scrotum, and to the integuments of the under part of the penis. The trunk formed by the assembling of these several ramifications, follows the course of the internal pudic artery to which it belongs, and gets into the pelvis at the lower part of the sciatic foramen, where it contributes to the formation of the hypogastric vein. The Plexus Uterinus consists in a considerable number of veins, which are distributed upon the surface, and in the texture of the uterus; they are also found in abundance in the broad ligaments, where they anastomose with the ovarial veins. The Plexus Vaginalis comes from the anterior parts of the or- gans of generation constituting the vulva, as the labia majora, minora, and so on. It also arises from the whole surface of the vagina, surrounds it completely, and anastomoses with the uterine veins. The Gluteal, the Obturator, and the Ilio-Lumbar Veins, also contribute to the Hypogastric; their description conforms so nearly VEINS OF THE ABDOMEN. 287 to that of the corresponding arteries, that it is unnecessary to de- tail it. The Primitive Iliac Vein, (Vena Iliaca Primitiva, Communis,) formed by the junction of the External and of the Internal Iliac, extends from the sacro-iliac symphysis to the lower margin of the fourth lumbar vertebra, where it joins the corresponding trunk of the opposite side of the body, to form the commencement of the ascending vena cava. In this course the left one passes obliquely across the body of the fifth lumbar vertebra, and beneath the right primitive iliac artery. The Vena Cava Inferior is situated on the front of the spinal column, to its right side, and extends from the lower part of the fourth lumbar vertebra; or, in other words, from the junction of the primitive iliac veins to the under end of the right auricle of the heart, into which it empties. It is larger than the Descending Cava. In its ascent it inclines very gradually to the right side of the spine, so as to reach the opening in the tendinous centre of the dia- phragm, through which it passes just before it terminates in the auricle. It is bounded on the left side by the aorta; and above the latter it is in front of the left crus of the diaphragm. Its lower extremity is crossed in front by the root of the primitive iliac arte-. ry; it is also crossed in its ascent by the duodenum and the pan- creas. Its upper extremity is behind the liver, and frequently passes through the substance of this viscus. It receives the middle sacral, the lumbar, the spermatic, the emulgent, the capsular, the hepatic, and the phrenic veins. The Middle Sacral Vein (Vena Sacra Media) forms, as has been just mentioned in the account of the branches of the hypo- gastric vein, a part of the sacral plexus. Its trunk follows the course of the middle sacral artery on the front of the sacrum, and discharges into the commencement of the vena cava, in the fork formed by the junction of the primitive iliacs. The Lumbar Veins (Vena Lumbales) correspond with the lum- bar arteries, and are commonly four or five in number on each side. Their primitive roots anastomose with the epigastric, the 288 CIRCULATORY SYSTEM. last intercostal, and the circumflex iliac veins ; the dorsal branches of them also anastomose with the vertebral sinuses, through the intervertebral foramina. Their trunks pass along with the arte- ries, between the bodies of the vertebrae and the psoas magnus muscle, or through the fasciculi of the latter: those on the left side pass behind the aorta, in order to reach the vena cava, and are, consequently, longer than such as are on the right. The Spermatic Veins (Vena Spermatica.) The right one ex- tends from the testicle to the ascending cava, just below the emul- gent veins; while the one on the left empties into the left emulgent vein. They are larger than the corresponding arteries, and pre- sent some peculiarities in the two sexes. In the male, the extremities of these veins begin in the testicle, and issue from it through the tunica albuginea; some of them also arise from the epididymis. They anastomose with the superficial veins of the penis and of the scrotum, and disengaging themselves from the tunica vaginalis, at its back part, are assembled into four or five anastomosing trunks; which envelop the vas deferens and the spermatic artery, and compose a principal part of the bulk of the chord. Having passed through the abdominal canal, they are reduced on each side to one trunk, which creeps along the sper- matic artery on the front of the psoas magnus muscle, and in com- pany with the ureter. Somewhat below the kidney, the spermatic vein is again resolved into a sort of plexus, having frequent addi- tions from the veins, in the adipose substance of the kidney, and some also from the branches of the vena portarum in the mesentery, and in the mesocolon. It then is reduced once more into a single trunk, which terminates as mentioned. The term Corpus Pampi- niforme (vine-like) is, by some anatomists, limited to the last plexus formed by each spermatic vein, but it is also frequently extended to both.* In the female, the spermatic vein is not so large as in the male; it comes from the ovarium and from the side of the uterus, and is joined by some small branches from the round ligament of the uterus, and from the Fallopian tube. Passing outwardly between the laminae of the broad ligament of the uterus, it crosses the ex- * H. Cloquet, Trait. D'Anat. VEINS OF THE ABDOMEN. 289 ternal iliac artery, and in the subsequent part of its course is. dis- posed of as in the male. The Emulgent Veins {Vena Emulgentes, Renales) are com- monly two in number, one on each side, and extend horizontally from the fissure of the kidneys to the ascending cava. They are of a considerable size, and owing to the position of the vena cava, the left is much longer than the right, and crosses in front of the aorta. They open on their respective sides of the cava opposite to each other. The branches of which the emulgent vein is com- posed, coming from the ramifications of the corresponding artery in the kidney, assemble into the single trunk near the fissure of the kidney: this trunk is joined by some small veins from the adjacent adipose matter and from the capsulae renales, and on the left side, as mentioned, it is also joined by the spermatic vein. The Capsular Veins (Vena Capsulares) arise from the arteries- spent upon the capsulae renales; and are two in number, one on each side.. That on the right discharges into the vena cava,. while the one on the left empties into the left emulgent most fre- quently. The Hepatic Veins (Vena Hepatica) take their rise in the liver, and collect into three principal trunks, which converging towards the ascending cava, discharge themselves into it, where it adheres to the posterior margin of the liver, immediately below the dia- phragm. Two of these trunks come from the right lobe, and one from the left, moreover, there are several small hepatic veins which discharge themselves into the cava, and come principally from the Lobulus Spigelii. The Inferior Phrenic Veins (Vena Phrenica Inferiores) come from the diaphragm, from the corresponding arteries. They are two in number, and discharge into the ascending cava just above the hepatic veins. SECT. V.—K)F THE VENA PORTARUM. The Vena Portarum is derived from the viscera of the abdo- men, and presents the singularity of a vein ramifying through a 290 CIRCULATORY SYSTEM. gland, the liver, before its blood is returned to the general circu- lation. The arteries from which it draws its supply of blood are the superior and the inferior mesenteric, and the cceliac with the exception of its hepatic branch. The viscera of the abdomen, which contribute to it are the spleen, the gall-bladder, the pan- creas, the stomach, the small and large intestines, and the large , and the small omentum. a. The Splenic Vein (Vena Splenica) is formed by several branches, which coming out distinctly from the fissure of the spleen, unite after a short course into a single trunk. This trunk runs in company with the splenic artery below it, along the superior margin of the pancreas, it is not quite so tortuous as the artery itself, and proceeding from left to right, is joined to the superior mesenteric vein in front of the vertebral column. In this course, the splenic receives the small veins,* (Vense Breves,) corresponding with the vasa brevia of the great end of the stomach, and then, successively, several branches from the pancreas. It likewise receives the gastric, or the superior coro- nary vein of the stomach, the right gastro-epiploic, and the left gastro-epiploic of the same viscus, all of which correspond with the arteries distributed to the latter. b. The Inferior Mesenteric Vein (Vena Meseraica Inferior) corresponds with the inferior mesenteric artery, and, consequently, derives its primitive branches from the rectum by the upper he- morrhoidal veins, which anastomose with the lower; from the sigmoid flexure of the colon, and from the left descending portion of the latter. The trunk formed by these branches, ascends be- hind the peritoneum, between the left ureter and the aorta; and going up behind the pancreas, is discharged into the splenic vein an inch or two from its termination. But, like the veins belonging to the lesser curvature, and the right side of the stomach, it some- times empties directly into the vena portarum, or into the upper end of the superior mesenteric. c. The Superior Mesenteric Vein (Vena Meseraica Superior) is the largest of the trunks which contribute to form the vena por- tarum. It is derived from the ramifications of the superior mesen- * M. Bauer discovered, in 1824, valves in these vessels, contrary to the general analogy of the system ef the Vena Portarum. His observations have been con- firmed by H. Cloquet. VENA PORTARUM. 291 teric artery upon the small intestines, the ileo-colic valve, the right ascending and the transverse colon. Its branches constitute in the mesentery and the mesocolon a vascular intertexture, forming arches and meshes adhering to the corresponding ones of the arte- ries. In the transverse mesocolon, it, like the artery, anastomoses with the inferior mesenteric vein. Its trunk being formed by the union of these several branches, ascends the mesentery, and goes in front of the duodenum, where the latter crosses the spine; im- mediately afterwards it gets behind the pancreas, and near its right end is joined by the splenic vein. It here, also, receives small branches from the duodenum, from the pylorus, and from the gall- bladder. The trunk of the Vena Portarum being formed behind the pan- creas by the union of the superior mesenteric with the splenic vein, extends from this point to the transverse fissure of the liver, and is about four inches in length. It ascends obliquely from left to right, behind the second curvature of the duodenum, being bounded on the right side by the biliary ducts, and on the left by the hepatic artery, where it is surrounded by a great many nervous filaments and lymphatic vessels, with all of which it is united by a common envelope of cellular substance, and of peritoneum, called the cap- sule of Glisson. Having reached the transverse fissure of the liver, it divides into two branches, which are each at a right angle to it, but in line with one another: they constitute the Sinus Por- tarum, of which the right branch being spent upon the great lobe, and the left upon the small lobe of the liver, are ramified almost to infinity through the structure of the latter. The terminating branches of the vena portarum empty into the venae hepaticae. Several cases are recorded in the annals of anatomy in which the vena portarum, instead of going into the liver, discharged im- mediately into the ascending cava.* In such instances the hepatic artery is much larger than usual. According to J. F. Meckel, notwithstanding they are anomalies, yet, as in most other cases of deviation from the general type of the human family, a striking analogy may be found between them and what occurs in some of * Lieutaud, Hist. Anat. Med. Huber, Obs. Anat. p. 34. Abernethy, Ph. Tr. 1793, part. i. Lawrence, Med. Ch. Trans, vol. v. 292 CIRCULATORY SYSTEM. the lower orders of animals. Here the analogy exists with the invertebrated animals. CHAPTER IV. Of the Peculiarities in the Circulatory System of the Foetus. Owing to the want of respiration in the foetus, its circulation is conducted in a manner very different from that of the adult. Moreover, its parasitical life requires an alliance, through the organs of circulation, with the mother. Its peculiarities, therefore, may be studied under two heads: those which arise from the want of respiration, and those which are required for its nourish- ment. The peculiarities of the first order are situated in the thorax, and those of the second in the abdomen. SECT. I.—OF THE PECULIARITIES OF THE FOSTUS, ARISING FROM THE WANT OF RESPIRATION. The Heart, at a very short period after conception, so early as about the end of the first month, is sufficiently developed to be in a state of great activity. The first indication of its existence, and, indeed, of the life of the new animal, is a small tremulous point, called the Punctum Saliens, from its incessant motion. The mus- cular structure of it is soon evolved, and in a few weeks becomes very manifest. At the earliest visible period of the heart in the incubated egg, which affords a satisfactory analogy, it consists of two vesicles united by a canal, (Canalis Auricularis of Haller.) One of the vesicles is the right auricle; the other is the left ventri- cle, and is probably the first to pulsate. The aorta is also visible, as well as the venae cavae. The circulation, at this period, is very simple: the blood, starting from the left ventricle, is propelled into the aorta; it is collected from the ramifications of the last into the two venae cavae, and thereby brought to the right auricle; it is then propelled by the right auricle through the canalis auricularis into the left ventricle, whereby its round is completed, and it then starts again. This is the most simple kind of circulation, and is found, PECULIARITIES OF THE FCETUS. 293 in fact, during the whole life of such animals as do not breathe by lungs; for example, fish. As the gills in them take the place of lungs, a branch from the aorta, spent upon the gills, is sufficient for their purposes of respiration. The terms right auricle and left ventricle have been used, be- cause the cavities alluded to perform the functions of the adult state; but in the progress of the development of the heart, a parti- tion begins to show itself which ultimately divides each of them into two distinct chambers, whereby we have a right auricle and a left one, a left ventricle and a right one. And the canalis auricularis is reduced from a canal into a short orifice, called Ostium Venosum, communicating from the auricles to the ventri- cles, and which is afterwards divided into two, one for either side of the heart. The partition between the ventricles is completed about the end of the second month of gestation, at a period when the aorta, from having been simple originally, is converted into two canals, one of which becomes the pulmonary artery. The partition between the auricles is not completed till birth. In cases of monstrosity, it is interesting to see how much the heart, at the end of uterine life, has still preserved this original type of simpli- city. I have formerly dissected a double foetus, where, from the parasitical character of one, no effort had been made for the deve- lopment of the lungs of the latter. The consequence of which was, the parasite's heart consisted only of the right auricle and of" the left ventricle, and the pulmonary artery had not been formed at all, there being but the single tube, the aorta, which led from the left ventricle, and had a sort of arrangement in its branches depending upon the tendency to form pulmonary arteries.* At birth, the auricular septum has advanced so far that the com- munication between the two cavities is kept up only by a defi- ciency, called the Foramen Ovale. This foramen, marked by a depression on the right side, admits a small quill, when conducted obliquely through it, and is protected on the left side by a valve, the edge of which is upwards, and which, when applied, is just large enough to cover the whole foramen. The moment that the blood ceases to pass through the foramen ovale, which occurs at the first act of inspiration, the valve is applied, and the aperture * For a detail of this case, see North American Medical and Surgical Journal; Philad., Oct., 1826. Vol. II.—26 294 CIRCULATING SYSTEM. grows up by the adhesion of its edge. The mechanism of this process is sufficiently simple. So long as the principal current of the blood was into the right auricle, the valve was pushed off from the side of the septum; but as breathing establishes, through the lungs, pulmonary veins, and left auricle, a current of circulation equivalent, both in quantity and force, to that through the two venae cavae and right auricle, a perfect equilibrium between the auricles is established, and the valve retains its place against the septum. Notwithstanding the incessant action of the auricles, during all the subsequent periods of life, this equilibrium, in the force and time of their contraction, remains uniform : a circumstance proved, conclusively, by the health and strength of adults in whom the valve has never adhered to the day of their death ; an observation made by many anatomists, and of which I have witnessed seve- ral examples. In one of them I passed two fingers readily from one auricle into the other, owing to the unusual size of the aper- ture. The valve which closes the foramen ovale is, first of all, scarcely perceptible; but as the foetus advances in age, the valve advances in size, and is, indeed, large enough to close the foramen some weeks before birth. It is formed from the lining membrane of the two auricles, with an intermediate cellular substance. The Valve of Eustachius, which exists also in the adult heart, is placed at the anterior semi-circumference of the orifice of the ascending vena cava in the right auricle, one of its ends adhering to the anterior margin of the foramen ovale. This valve, contrary to the one in the foramen ovale, is larger in proportion as .the foetus is younger, and, when first observed, covers the whole orifice of the vena cava ascendens; its opening, however, is in the direction of the current of blood in the latter. It also is formed by a dupli- cature of the lining membrane of the auricle; and, from its dispo- sition, determines the blood of the ascending cava to flow through the foramen ovale into the left auricle, either wholly or in part, according to the period of gestation. Its obliquity also gives a direction to the blood of the descending cava, into the right ven- tricle from the right auricle. These uses of the Eustachian valve were pointed out by the celebrated Sabatier:* their value will be illustrated hereafter. * Traite d'Anat. vol. ii. p. 296. PECULIARITIES OF THE F02TUS. 295 The ventricles of the Heart, at birth, have the same structure and internal arrangement as afterwards; they are remarkable, however, for being of equal thickness, or nearly so, an observation of Mr. John Hunter.* This fact is connected with the circum- stance of their both contributing to the aortic circulation till respi- ration begins, owing to the pulmonary artery entering, during fcetal life, by its largest branch, into the aorta. The Ductus Arteriosus constitutes this branch of the pulmonary artery, and is, in fact, the continuation of the trunk of the latter into the aorta, immediately behind the origin of the left subclavian artery. The right and the left pulmonary artery at this period, are but inconsiderable trunks, incapable by any means of carry- ing off all the blood of the right ventricle; the greater part of it, therefore, is conveyed by the ductus arteriosus into the descending aorta. As the contraction of the ventricles, like that of the auri- cles, is synchronous, it is evident that the column of blood in the descending aorta, is acted upon by both ventricles at the same moment. The ductus arteriosus preserves the principle of a single circula- tion in the foetus, which was first of all manifested by the two ventricles, constituting but one cavity, and by the aorta and pul- monary artery being but one trunk. At the first act of inspiration the lungs, which were before solid, and the thorax, which was compressed, are greatly augmented in volume by the introduction of air. The dilatation of the thorax, besides introducing air through the trachea, causes an increased flow of blood through the right and left pulmonary arteries, in order to fill the vacuum in the lungs. The pulmonary arteries become in that way perma- nently dilated, and the circulation is finally drawn off entirely from the ductus arteriosus, though this takes several weeks or months before it is completely accomplished. The ductus arteriosus in this time is continually contracting, and is at length converted into a ligamentous chord, like other arteries, whose circulation has been arrested. These are the several peculiarities which distinguish the foetal circulation, owing to the privation of respiration; and it is clear, * Animal GEconomy. 296 CIRCULATORY SYSTEM. that the collective result is that of a circulation quite as simple as if the heart consisted of but two cavities; while, at the same time, it keeps this organ in a state of preparation for carrying on two distinct circulations, one pulmonary and the other aortic, from the moment that respiration begins: so that the whole mass of blood is, in subsequent life, brought successively under the influence of respiration, by having to pass unavoidably through the lungs. SECT. II.— OF THE PECULIARITIES OF THE CIRCULATION OF THE FCETUS CONNECTED WITH ITS NOURISHMENT. The Umbilical Vein, one of the constituents of the umbilical chord, brings the blood from the placenta to the foetus. This ves- sel is from three to four lines in diameter, and enters at the navel; thence it goes along the free margin of the suspensory ligament of the liver, and traverses the anterior half of the umbilical fissure, to terminate in the left branch of the sinus of the vena portarum. In this course through the liver, the umbilical vein sends off to the right and the left lobe, several small branches. As the intestinal circulation of the foetus is too small to send much blood, through the vena portarum, it would be sufficiently correct to consider the sinus venae portarum as the bifurcation of the umbilical vein: but, as this might introduce a confusion into the description, it will be better to retain the adult nomenclature. The Ductus Venosus is a vein which occupies the posterior, half of the umbilical fissure, and is about a line and a half in diameter. It arises from the left branch of the sinus portarum, opposite to the place where the umbilical vein entered or terminated, and is con- sequently in the same line with the latter. Traversing the poste- rior part of the umbilical fissure, it terminates in the left vena cava hepatica, as this vein is about joining the ascending cava, just be- low the tendinous centre of the diaphragm. Through this route much of the blood of the umbilical vein is carried directly to the right auricle of the heart, and then passed through the foramen ovale into the left auricle by the mechanism of the Eustachian valve. From these considerations, it is evident that the umbilical vein PECULIARITIES OF THE FOZTUS. 297 really performs the office of a vein till it reaches the liver, but that there, much of its blood is spent through the portal circulation, upon the structure of this viscus, and that what remains is carried through the ductus venosus to the heart. Like other veins, it is furnished with valves, of which there are two; one at its termina- tion in the sinus portarum, and the other at the cardiac extremity of the ductus venosus.* The establishment of respiration, by put- ting the circulation into other channels, likewise causes its oblite- ration and final conversion into a ligamentous chord. The valve, at the sinus portarum, prevents the blood from taking a retrograde course, and thereby keeping the umbilical vein open; the valve of the ductus venosus has the same effect upon the duct to which it belongs, and is aided by the current of blood in the left branch of the sinus portarum, setting across the mouth of the ductus venosus instead of plunging into it from the umbilical vein, as in foetal life. It is worthy of remark, that the left branch of the sinus porta- rum is bounded, on its right extremity, by the end of the vena por- tarum, and receives, about its middle, the umbilical vein. In the space, then, between the umbilical vein and the portal, the circula- tion, from the predominance of umbilical blood in foetal life, is con- ducted from left to right, but afterwards from right to left, as the portal circulation is established and the other is arrested. The Umbilical Arteries discharge the important office of con- ducting the effete blood of the foetus to the placenta. They are the continuations of the internal iliacs, and are two in number, one on either side; they conduct off so much of the blood of the primi- tive iliacs, as to leave the external iliacs of a very small size. During the early months of uterine life, they are rather, indeed the continued trunks of thb primitive iliacs, the branches from the latter being then so little developed as to appear quite subordinate to the chief function of carrying the blood out of the foetus to the placenta. But as the inferior extremities and the buttocks grow, these subordinate branches are more and more evolved. At, birth, the umbilical arteries, after dipping very superficially into the pelvis, rise up at the sides of the bladder and converge towards the navel. They emerge at the latter, cling together and traverse the umbilical chord by twisting spirally around the umbi- * Bichat, Anat. Descrip. vol. v. p. 419. 26* 298 CIRCULATORY SYSTEM. heal vein, like two small strings wound in this way upon a larger one. Their diameter is from a line to a line and a half. They anastomose as they join the placenta, but not previously. Like the circulation between arteries and veins in other parts of the body, the capillaries of the umbilical arteries terminate in those of the umbilical vein in the placenta. From the observations of Wrisberg, Osiander and the highly distinguished Professor Chap- man of the University of Pennsylvania, it seems that there is no direct vascular communication between the mother and the foetus. This opinion is founded upon the leading facts, that the finest injections do not pass from one to the other; that foetuses, after the death of the mother from haemorrhage, still live and retain their usual quantity of blood; that if the foetus be expelled entire with the placenta, and membranes unhurt, the circulation still continues. One example of which was witnessed nine minutes by Wrisberg;* another fifteen by Osiander ;f some from ten to twenty minutes by Professor Chapman;J another for an hour by Professor Channing of Boston, and Dr. Selby of Tennessee,§ where a bath of tepid water was used to resuscitate the foetus. Also, from the observa- tions of Breschet, it seems that the globules of the blood of the foetus, when inspected by the microscope, are different in appear- ance from those of the mother.([ Mascagni says that he has made several most minute injections of the pregnant uterus, so as to cover with small vessels its whole internal surface, and to return the injection by the uterine veins: and yet he has never succeeded in injecting, in that way, the se- cundines.H I have, myself, repeatedly tried by minute injection to pass arti- cles from the fcetal into the maternal vessels, and the reverse, but always without success; in two instances, the experiment was upon human subjects, and, in the others, on the cow. In one of the lat- ter, I perceived'that some of the injecting matter thrown into the fcetal vessels had got into the uterine veins; but as the observation was in opposition to all the others, and solitary, I have no disposi- tion to array it against them, at least, until farther and more de- cided experience. My second experiment on the human subject * Meckel, Man. D'Anat. vol. iii. p. 163. + Id. J Chapman's Med. and Phys. Journal, vol. i. p. 6. § Id. II Am. Med. Jour. vol. i. p. 193. T Prodromo, vol. i. p. 127. PECULIARITIES OF THE F03TUS. 299 was made in April, 1833, under the following circumstances: A white female, aged 24, died at the Alms House, suddenly, and in the ninth month of pregnancy, the foetus was still in utero, but the membranes were ruptured. In the presence of several of the phy- sicians and students, and with the assistance of my young friend, Dr. Goddard, to whose suggestions and manipulations I am in- debted for the chemical compounds resorted to, I injected through the aorta one gallon of the saturated solution of Prussiate of potash, and followed it with an equal quantity of a saturated solution of sul- phate of iron. The injection penetrated very minutely, as might be expected, and the precipitate of Prussian blue coloured deeply many parts of the skin. On dissecting the uterus, the uterine ar- teries were found well injected, but the injection did not reach the umbilical vein or arteries, as was proved both by simple inspection and by chemical tests. Having cut out the uterus and taken it to the University, the ex- periment was continued the next dayjn the presence of a large concourse of students and several physicians. The umbilical ves- sels were first of all injected with a saturated solution of bichro- mate of potash, and then with a saturated solution of sugar of lead, the result was a strong, yellow precipitate, the bichromate of lead. The injection passed reciprocally from the arteries into the vein, and from the vein into the arteries, conformably to the direction in which it was thrown for the time. The sinuses of the uterus were then injected with similar materials to those of the uterine arteries; to wit, a solution of Prussiate of potash, followed by one of sulJ phate of iron. The umbilical vessels were then all filled with liquid plaster of Paris coloured yellow: and the uterine sinuses with liquid plaster of Paris coloured blue, of which they readily received eighteen ounces. A short time having been allowed for the setting of the injection, I cut into the substance of the uterus and of the placenta. No yellow injection was found in the vessels of the uterus, nor was there any blue injection found in the umbilical vessels of the pla- centa ; there was, therefore, a deficiency of evidence of direct vas- cular communication between the foetus and the mother. The placenta was infiltrated with Prussiate of iron, and considerable quantities of blue plaster were found in the cavity of the uterus. In the progress of the injection with the Prussiate of iron, into 300 CIRCULATORY SYSTEM. the uterine sinuses, the membranes were raised from the uterus in vesications. The parts having been distended and put aside to dry, at the end of a fortnight they were examined again by incisions, and the same evidence of the want of direct vascular communication was renewed. But the placenta was found to be infiltrated according to certain rules seeming to depend on its organization. The blue colouring matter on the part of the uterus, and the yellow on the part of the foetus, determined in it two parts, one uterine and the other foetal, closely and alternately interlocked, like a dove-tailing: the uterine processes passed to within a short distance of the free surface of the placenta, while the foetal processes went almost to the base of the placenta. The confines of the two colours were defined well by this abrupt termination, the borders of these dove- tails. The appearance would, perhaps, be better designated by the terms uterine lobes, and foetal lobes, alternately penetrating, so as to constitute the whole mass of the placenta. No distinct ves- sel of a blue colour could, however, be seen in the uterine lobes; but a few very spare yellow ones were visible. On raising up these uterine divisions, the orifices of the uterine sinuses were seen at their base. The inference from this experiment is, that though there is no direct connexion of blood vessels between the mother and the foetus, yet there is a part of the placenta which seems to hold a special connexion with the uterine sinuses, and which may pos-, sibly, therefore, by interstitial circulation, establish a connexion with the foetus. The facts are at any rate presented as they oc- curred. The effete blood of the umbilical arteries becomes regenerated in the placenta, assumes a brighter hue, and is returned to the foetus by the umbilical vein. According to the theory of Sabatier concerning the use of the Eustachian valve, if the latter did not exist, the fresh blood brought to the heart by the ductus venosus, instead of being diverted into the left auricle through the foramen ovale, would be received by the right auricle, and transmitted, either wholly or in a great degree, into the right ventricle. It would then be passed from the latter through the pulmonary artery and ductus arteriosus into the descending aorta, so that no part of the system, above the junction of the duct with the aorta, could receive the benefit of it: this would leave the head and upper ex- ANATOMY OF THE ABSORBENT SYSTEM. 301 tremities unsupplied with fresh blood. Moreover, much of the latter would be fruitlessly introduced, for it would depart almost immediately through the umbilical arteries. But the Eustachian valve determining the flow of blood of the ascending cava into the left auricle, its passage into the left ventricle is a matter of course: thence it begins the aortic circulation fairly, so that every part of the system participates in its benefits. The celebrated Wistar* has also happily suggested, that without this arrangement the blood of the coronary arteries of the heart itself, the purity of which is so essential to the vigour of circula- tion, would otherwise have been effete, and, consequently, unfit for its object of refreshing the heart. The umbilical arteries become the round ligaments of the blad- der, after the circulation through them has ceased, with the excep- tion of their pelvic extremities, which subsequently constitute the trunks of the Internal Iliac Arteries. CHAPTER V. Of the General Anatomy of the Absorbent System. The absorbent system is one of the most interesting of those which compose the human body, both on account of its very gene- ral diffusion, and of the office of interstitial absorption that it in- cessantly carries on, thereby removing the effete parts of the body and making room for the deposite of new ones. It is also called the lymphatic system, owing to the transparent colour of the fluid which it conducts. With the exception of an imperfect observation of some of these vessels in the mesentery of a goat, by Herophilus and Erasistra- tus, 280 years before Christ, during the reigns of the Ptolemies in Egypt, what is known of them is entirely a modern acquisition in anatomy. In 1564, Eustachius discovered the thoracic duct of a * System of Anat. vol. ii. p. 76, 3d edition. 302 CIRCULATORY SYSTEM. horse, which in the ignorance of its use, he called vena alba tho- racis. This fact remained insulated and almost forgotten for seventy years. In 1622, Asellius discovered the absorbents of the mesentery, and in the discussions consequent thereto, the original observation of Herophilus and Erasistratus was raised from an oblivion of nineteen centuries, to be again brought to light and admired. Asellius seems to have understood that the absorbents of the mesentery collect the chyle from the intestines, but his knowledge ceased there, for he thought that they discharged into the vena portarum.* In 1634, Weslingius saw the thoracic duct again; and in 1649, ascertained that the chyliferous vessels of Asellius terminated in it. In 1650, Olaus Rudbeck, a young man pursuing his anatomical studies in Leyden, saw first the lymphatic vessels of the liver, and in a few months afterwards injected simi- lar ones in the loins, in the thorax, in the groins, and in the arm- pits. Thomas Bartholine, a teacher of great reputation in those days, in a dissertation, dated in 1652, claimed for himself the priority of these observations, and from the obscurity of Rudbeck, enjoyed for some time the merit of them. In 1654, Rudbeck pub- lished and set forth his own pretensions with such force, that he finally triumphed over his antagonist, but not until the whole world of anatomy had been set in commotion; one party being for the professor, and the other for the pupil, and many bloody strifes having arisen between the students of the respective sides. In 1653, Jolyff, a celebrated anatomist, of London, proclaimed his own rights to this warmly contested honour; but the period being rather late, his name is scarcely associated with the history of these feuds. Almost a century then passed before there were many important additions to the knowledge of those times. After which great contributions were made by Dr. A. Munro,f Dr. W. Hunter,J Hewson,§ Cruikshank,|| but chiefly by the celebrated Mascagni,! who, having imagined finely pointed instruments of * It is somewhat remarkable, that the celebrated Harvey, who had himself so much to complain of, in the obstinacy with which his cotemporaries adhered to ancient errors, for thirty years resisted the discovery of Asellius, and died, finally, protesting against it. + De Venis Lymph. Valv. Berlin, 1757-70. X Med. Comment. London, 1762-77. § Experimental Inquiries, London, 1774-77. || Anat. of the Lymphatics, London, 1774-90. T Vasor. Lymph. Corp. Hum. Historia et Ichnographia, Sienne, 1787. ANATOMY OF THE ABSORBENT SYSTEM. 303 glass for executing his injections of these vessels, succeeded in demonstrating them in almost every part of the body, excepting the spinal marrow, the brain, the ball of the eye, and perhaps the placenta. In some of these parts, however, he says he has seen them, and he speaks confidently of their existence, without excep- tion, every where, even in the enamel of the teeth.* The Lymphatic Vessels are small, pellucid, transparent cylin- drical tubes, generally of about a line or less in diameter, whose trunks have been traced to all the external and internal surfaces of the body, and to the depth of all the organs, with the exceptions stated. It is only very lately, however, that their existence on the external surface of the skin has been put beyond doubt, by the observailions and injections of M. Lauth.f Their origin is so at- tenuated, that anatomists have come to no satisfactory conclusion in regard to its manner. The visible origin of the absorbents is, however, in some parts, as in the intestinal canal and on the glans penis, according to Breschet, as a reticulated intertexture, the meshes of which are so close as to leave scarcely an interval between them. In the peritoneal coat of the liver this reticulation is so fine and close that the membrane appears to be composed wholly of them: their connexion, however, with the deeper absorbents is so close that they cannot be preserved in this state owing to the subsidence of the injection, especially if it be mercury. Professor Fohman, of Heidelberg, whose injections are said to be of a most superior kind, is of opinion that in many cases these vessels have a cellular origin, such at least is the appearance of those in the cornea and in the umbilical chord injected by him. Muller, however, doubts the accuracy of his conclusions in regard to the character of these cells. J Fohman is indeed of opinion that the cellular substance consists merely of lymphatics. The earlier cultivators of this branch of study, not knowing their absorbent properties, conceived them to be continuations of the arteries applied to the reconducting of the serous part of the blood to the heart; and considered the opinion substantiated by * Prodromo della Grande Anatomia, vol. i. p. 1. t Essai sur les Vaisseaux Lymph. Strasburg, 1824. X Loc. cit. p. 283. 304 CIRCULATORY SYSTEM. the circumstance of their being occasionally filled by fine injec- tions thrown into the arteries. More improved views of their uses caused the abandonment of this theory, and the substitution of their absorbing powers; in which case the minds of anatomists became divided between the ampulla-like mouth, or wide patulous origin of Lieberkuhn, and the small orifices of Hewson. It is, perhaps, not possible to solve the question in regard to the mode of origin of the lymphatics, at least, in most parts of the body. Meckel, about the middle of the last century, asserted their con- tinuity with the veins. Mr. Ribes has seen matter injected into the vena portarum find its way into the lymphatics of the liver. On this subject, M. Chaussier says,* that, ignorant of the man- ner in which the arteries, veins, nerves, and lymphatics, arrange themselves collectively into a glandular structure, or, in other words, into a capillary system, we cannot avoid ignorance of the part acted by the lymphatics alone; we only know that the minute lymphatics form a portion of the elements of each viscus and structure of the body, and that they only become visible in be- coming larger trunks. The absorbents, in proceeding from their origins, in general become larger and less numerous, and form frequent anastomoses with one another. The proportionate increase of magnitude from the successive junction of trunks is, however, by no means equal to what occurs in the veins. The larger superficial absorbent trunks of the extremities have not so much disposition to run into one another, hence they retain a size almost uniform from one end of the limb to the other. When fully distended, the appear- ance of absorbents is not regularly cylindrical, but knotted, owing to the frequent valvular interruptions to their cavities. The ab- sorbents, from all parts of the body, are finally united into two tubes; one on the left, and the other on the right side of the trunk of the body, and which discharge their contents into the venous system, each on its respective side, at the junction of the internal jugular and subclavian vein. The trunk on the right side receives the lymphatics of the right side of the head and neck, of the right lung, and right superior extremity; while the trunk on the left, called the thoracic duct, receives all the chyliferous vessels and the lymphatics of the remaining part of the body. It would ap- * Diet, des Sciences Med. Art. Lymphatiques. ANATOMY OF THE ABSORBENT SYSTEM. 305 pear, from the observations of the younger Lauth,* that there are also other terminations of the lymphatics in the veins; to wit, such as in the yet capillary state end in the veins of the minute struc- ture of organs, and such as empty into them in the interior of the lymphatic glands. Previously to Lauth, this sentiment of com- munication with the veins was strongly advocated by several anatomists and physiologists, for the following reasons: 1. That the known roots of the lymphatic system have an area much superior to that of the trunks in which they terminate. 2. That substances introduced into certain lymphatics by absorption or injection, have been found in the contiguous veins. 3. That a ligature upon the thoracic duct produced death only after ten or fifteen days, and then the articles which had been absorbed by the intestines, were found in the blood. 4. And that injections had proved this communication. Notwithstanding the well known fact of injections, under cer- tain circumstances, passing from the arteries into the lymphatics, some anatomists of modern date have hesitated in admitting a direct communication. M. Meckel has, indeed, rejected the no- tion entirely, on the ground that the fluid contained in the trunks of the absorbents is always the same as one finds at their com- mencement. For example, the lymphatics coming from the liver contain a fluid like bile; those which come from the mammae contain a fluid like milk; those which come from parts suffering from an extravasation of blood contain a sanguineous fluid; the bronchial glands are coloured by the black pigment brought to them from the lungs; poisonous matter, as that of the small-pox or venereal, irritates and inflames the lymphatics that lie in the course of its introduction into the system. For these reasons it would appear to him, that the arteries do not continue themselves into the lymphatics as they do into the veins. The observations of M. Lauth seem to have proved the point, that some of the lymphatics take their origin from the internal surface of the arte- ries ; and it may be through them that injections have been forced from one system into the other. In the case of the liver of a child, I have injected its absorbents very successfully from the arteries. The coats of the lymphatics generally are too thin and trang- Vol. II.—27 * Loc. cit. 300 CIRCULATORY SYSTEM. parent for an investigation of their structure; but as those of the thoracic duct are sufficiently thick for the purpose, one may esti- mate the structure of other trunks by it. It is thus ascertained that they consist of two coats, an internal and an external one.* The external coat is somewhat irregular on its surface, from its connexion with the adjacent cellular substance; and has a fila- mentous appearance more deeply, which has been considered as fibrous, or muscular, by some anatomists, owing to its contraction upon the application of certain stimulants. The internal mem- brane is extremely fine and perfectly transparent, and is remark- able for its frequent duplications, whereby a system of valves is produced resembling those of the veins. These valves are gene- rally of a semi-lunar or parabolic shape, and are arranged in pairs, though according to Lauth,f some of them are circular, and do not close the canal entirely. The pairs are not placed at stated distances from one another, but vary in different parts of the body; in some places there are several in the course of an inch, and in others not one pair. As a general rule, they are less frequent as the trunk increases in magnitude; hence, the thoracic duct has but very few of them. The valves, by having their semi-circumference fixed, while the diameter is loose and inclined in the course of the circulation, prevent the retrograde movement of the contained fluid. An enlargement of the trunk at their outer face into sinuses, resembling those at the valves of the veins, gives also to the lymphatic trunk a knotted condition when it is fully in- jected. The coats of the lymphatic vessels, though very thin, are yet dense and extremely strong, much more in proportion than those of any other tubes. They are both extensible and elastic, possess striking powers of spontaneous contraction in the living body, and also in the dead, but to a less extent. They are furnished with a'rteries and veins, and probably with nerves also, from their sen- sibility in a state of inflammation. And, as they stand in need of a similar organization with other canals, their parietes are said also to have lymphatics. The absorbent vessels, are, by some, divided into lacteals and * Valentin asserts that there is also a middle coat, and Henle that there is an in- - ternal epithelium. t Loc. cit. ANATOMY OF THE ABSORBENT SYSTEM. 307 lymphatics,* the first term expressing those which convey the chyle from the intestines, and the second such as are found in other parts of the system. As the difference is more in the fluid conducted than in the structure of the vessels themselves, the divi- sion is rather superfluous. There is also a distinction of the lym- phatics, as in the veins, arising from their situation; some of them are called superficial, and the others deep-seated. The arrange- ment upon which this nomenclature depends, is found in the head, trunk, extremities, and in most of the viscera. The deep-seated trunks are the largest, but the least numerous in the muscular parts of the body. Of the Lymphatic Glands. The Lymphatic or Absorbent Glands or Ganglions, sometimes called waxen kernels in common language, are an appendage of a very important description to the absorbent system. They are flattened ovoidal bodies, of a reddish ash colour, indurated so as to afford a strong resistance to pressure, and of a variable volume, from a line to twelve lines in their long diameter. They are found principally in clusters or chains, and are more abundant in the neck, in the groin, in the arm-pit, in the mesentery, and about the bifur- cation of the trachea. The lymphatic vessels, in their course towards the thoracic duct, have to pass through one or more of these glands. This rule is almost universal; some exceptions, however, to it, in the case of the lower extremities, have been stated by Mr. Hewson, and in the case of the back, by Mr. Cruikshank:f the latter believes Mr. H. to have been under a misapprehension in this statement concerning the extremities, as it had not been verified by the result of his own investigations. The vessels that enter into the glands are called vasa inferentia, while those that depart from them are the vasa efferentia. As, owing to the juxtaposition of many of these glands, the vessels between them are very short, this distinction would * This division has been handed down from the time of Bartholine, who, not suspecting the absorbing powers of the lymphatics, held them only as organs of circulation for restoring to the heart the serum of the blood. The sagacious mind of Dr. VV. Hunter first imagined their absorbing powers, and established the theory of their identity of function, in this respect, with the lacteals. The priority of the theory was warmly contested for Dr. Monroe, of Edinburgh. t Anat. of Absorb. Vessels, second edit. p. 79. London, 1790. 308 CIRCULATORY SYSTEM. likewise seem almost superfluous, because there is scarcely space to apply the term efferentia, before the same vessels enter the con- secutive gland, thereby becoming inferentia. For the most part, the vasa inferentia are more numerous and somewhat smaller than the efferentia. The former, as they enter the gland, radiate into smaller branches, while the latter are formed from the junction of smaller branches. Each lymphatic gland is surrounded by a capsule, resembling condensed cellular substance, which adheres very closely to the gland, and from which cause many anatomists are disposed to deny its existence, at least as a distinct membrane. They are also abundantly furnished with arteries and with veins destitute of valves; but though they are penetrated by nervous filaments, it is not yet satisfactorily ascertained that any remain with them; it is, however, more probable than otherwise. Their connexion with the surrounding cellular substance is sufficiently loose to permit them, in certain parts, to be slid moderately backwards and for- wards. When this motion is arrested, it is from inflammation about them. The capsule of the lymphatic gland, like that of other glands, sends processes within to keep its parts together, and to conduct the blood vessels. It also contains a peculiar fluid called, by Haller, succus proprius, which is principally found in young ani- mals, diminishes as they advance in age, and finally disappears. It is of various colours, but more frequently white; it appears to have globular particles in it, which the late Mr. Hewson, for divers reasons, thought to become afterwards the red globules of blood. When a lymphatic gland is injected with quicksilver, it appears to be made up by the minute branching of the vasa inferentia, and the roots of the vasa efferentia, the former being continued into the latter. There is also some appearance of small cells inter- mediate to these two orders of vessels. All anatomists admit the former opinion; but many reject the latter, under a presumption that the appearance is delusive. The arguments, however, seem to be in favour of their existence. Mr. Cruikshank,* whose ad- dress in these matters was certainly of the first order, declares that he never failed to perceive them, and particularly well, just * Loc. cit., p. 85, pi. iii. ANATOMY OF THE ABSORBENT SYSTEM. 309 as the mercury was entering the gland. This arrangement is still more readily made out in animals, as the horse, ass, mule. It also seems, from his observations, that when there are more than one vas inferens and efferens, there are cells for each set, which are kept distinct from the cells of the others, though they communi- cate freely with their cognates. Mr. Abernethy's investigations, on the mesenteric glands of whales, coincide with the views of Mr. Cruikshank: he states, indeed, the cells as being large spherical bags, into which the lacteals plainly open. The celebrated Mas- cagni also acknowledges, and, in fact, describes the cellular struc- ture of these glands,* which he had ascertained both by quicksilver and by wax injections. The improved notions of modern anato- my, upon what is called the erectile tissue, that is, the cells inter- mediate to arteries and veins, as in the penis and other places, and now considered rather as the dilated extremities of vessels, would also assist in warranting the opinion advocated. The celebrated Ruysch thought that he had discovered acini in the lymphatic glands, and sent his injected preparations illustrative of them to Boerhaave. Some idea of the enthusiasm of the anatomists of old may be conceived by his saying," Quando jam clarius et perfectius videbam haec omnia, pras gaudio exsiliebam." When the absorbing powers of the lymphatics had been esta- blished by Dr. W. Hunter, they were for a long time considered as the exclusive functionaries in this operation; and the opinions pre- viously entertained had sunk into such disrepute, from some expe- riments of Mr. John Hunter.f that they were considered rather as food for literary research and curiosity, than for deliberate adoption. In the year 1809, M. Magendie reported his experi- ments on absorption, which seemed to favour the notion that the veins also assisted in this office, a theory as ancient as Galen. The more recent observations of Fohman, in 1821, and Lauth, in 1824, on the communications of the lymphatics with the veins, in the midst of the tissues of organs, and in the lymphatic glands, seem now to explain away again the theories of the absorbing powers of the veins, and to reinstate the lymphatics in their reputed * Vasor. Lymph. Hist. t M«d. Commentaries. 27* 310 CIRCULATORY SYSTEM. exclusive functions. It is also stated that an anatomist of Florence, M. Lippi, has still more lately found several large lymphatic trunks entering into the ascending cava. The connexion of the lymphatic system with the vena cava ascendens, and also with the external iliac veins has been farther demonstrated by certain preparations, exhibited by M. Amussat to the Academie Royale.* M. Fodera has, however, again brought the subject under discussion, by mul- tiplying the active agents of this function, and says, that his expe- riments prove that all organized tissues enjoy it, and not certain parts only, as has been heretofore supposed ;f from which it results that most of the rules in regard to the application of local remedies are inexact, and that we should have more regard to the thickness and density of tissues, to the quantity and rapidity of their circula- tion, than to simple locality .J CHAPTER VI. Of the Speeial Anatomy of the Absorbent System. SECT. I.—OF THE ABSORBENTS OF THE HEAD AND NECK. The Superficial Absorbents of the head are found in company with the several branches of the temporal, the occipital, the frontal, and the facial arteries, and, in order to get into the lymphatic trunks leading to the thoracic duct, follow or rather reverse the course of their respective arteries. There are at least two absor- bent trunks for one arterial, and frequently more: those on the face are more abundant than such as are on the side of the cra- nium, owing to the excess of cellular substance on the former. The absorbents of these two regions anastomose freely beneath the external ear, between the skin and the parotid gland. * Am. Med. Jour. vol. i. p. 422. t Recherches Experimentales sur P Absorption et l'Exhalation. Paris, 1824. t For a most interesting and instructive series of experiments on the laws and phenomena cf absorption, see Philadelphia Journal of the Medical and Physical Sciences. Nos. 6 and 10. The experiments were executed by Drs. Lawrence, B. H. Coates, and Harlan, of this city. ABSORBENTS OF THE HEAD AND NECK. 311 The Deep Seated Absorbents of the head have been followed to the membranes of the brain, but not farther. Ruysch observed them between the tunica arachnoidea and the pia mater, inflated with air, and called them vasa pseudo-lymphatica. Lancisius, Pacchioni, and others, assert their having found them in the pia mater. Doubts are cast upon these several observations, owing to such vessels not having been injected with quicksilver, and from the want of a valvular appearance in them; also from the want of lymphatic glands in the cavity for the brain. Their exist- ence, however, would seem to be sufficiently proved, both from general analogy, and from affections of the brain producing swell- ings in the glands of the neck. On the dura mater they have been traced along the course of its arteries. They descend from the interior of the cranium into the neck, along the carotid and verte- bral arteries. The absence of lymphatic glands in the cranium may be accounted for from the fact, that the ready tendency of these organs to swell upon slight causes of irritation, would have rendered the individual liable to death, from compression of the brain, by their tumefaction. Mr. Cruikshank considers himself to have found lymphatic glands in the carotid canal. The Deep Lymphatics of the face, as those from the interior of the nose, of the orbit, of the tongue and mouth, attend the arteries which respectively supply those parts. These several absorbents, from the surface and from the inte- rior of the head, descend to the base of the cranium, and then begin to pass through the chain of lymphatic glands situated along the course of the great blood vessels of the neck. They lie, for the most part, under the sterno-mastoid muscle, and, when suc- cessfully injected, are thought to form the most brilliant plexus of absorbents in the whole frame. On each side of the neck, one or more common trunks are, at length, formed; that on the left side joins the Left Thoracic Duct near its termination, while the one on the right assists in forming the duct peculiar to that side, the Right Thoracic Duct, or, more properly called, the right Brachio Cephalic. The lymphatic vessels of the muscles of the neck, and those of the thyroid gland, enter into the trunks of the neck. According to Mr. Cruikshank, those of the thyroid gland may be readily 312 CIRCULATORY SYSTEM. injected by plunging a lancet at random into its substance, and then introducing air or quicksilver. Of the Absorbent Glands of the Head and JVeck. The only claim of lymphatic glands to an existence in the cavity of the cranium, is founded upon the supposition that the Pineal, the Pituitary, and Pacchioni's Glands are of this character; but it is far from being established, and there seems indeed to be some doubt whether the glands found in the carotid canal, by Mr. Cruik- shank, are not the carotid 'ganglion of the Sympathetic, lately noticed by Laumonier. On the external surface of the cranium, over the insertion of the sterno-mastoid muscle, there are from four to six of a small volume; on the face there is one or more small ones, below the zygoma, and from two to four on the external surface of the parotid; there is one or more small ones situated in the substance of the parotid gland, which, according to Burns, are generally the seat of tumours falsely attributed to the parotid itself. There are also some small glands along the facial artery as it ascends from the base of the jaw to the corner of the mouth. On the neck there are two or more small glands, immediately under the skin of the symphysis of the jaw, and eight or nine around the submaxillary gland. The most numerous congeries of glands on the neck is, however, along its great blood vessels, and covered more or less by the sterno-mastoid muscle, being principally between its posterior margin and the anterior of the trapezius. Along the latter line there are about twenty, in addi- tion to six just above the superior margin of the clavicle. On the trachea, just above the sternum, there are four, forming the upper end of a series which descends along the oesophagus and trachea to the root of the lungs. SECT. II.—OF THE ABSORBENTS OF THE UPPER EXTREMITIES AND OF THE CONTIGUOUS PARTS OF THE TRUNK OF THE BODY. The superficial absorbents of the upper extremities are very nu- merous, and lie between the skin and aponeurosis. They begin at ABSORBENTS OF THE HEAD AND NECK. 313 the ends of the fingers and thumb; there being two or more branches for each, both before and behind. The posterior branches pass to the back of the hand and of the fore-arm: some of them, more especially those from about the thumb, run up along the radial side of the fore-arm to the bend of the arm ; but by far the greater part of them incline very gradually in a semi-spiral manner towards the ulna, and then to the front of the fore-arm. Such of the superficial vessels as come from the front of the fingers and hand, continue to ascend straight up the fore-arm to its bend. These vessels of the fore-arm are so numerous that for every few lines there is an ascending trunk on its circumference: some of them coalesce, others form plexuses, and their number is much reduced at the elbow. From the elbow the superficial lymphatics ascend to the axilla in fifteen or twenty, parallel trunks, along the internal margin and the front surface of the biceps flexor cubiti. The outer side of the arm has comparatively but few absorbent trunks upon it, but some follow the course of the cephalic vein, penetrate with it into the axilla, and then join the inferior lymphatics of the neck. The Deep Absorbents of the upper extremity attend the arteries, and are at least two for each principal artery. They anastomose with the superficial ones at intervals, and at last terminate in the axillary glands. As they follow strictly the course of the arteries, a farther specification is needless. The Superficial Absorbents of the contiguous portions of the trunk of the body are not by any means so numerous as those of the upper extremity; they consequently are more distant from one another, and they also go along in a more serpentine manner. From the nape of the neck to the lower part of the loins they all converge to the arm-pit.' The absorbents which are situated on the front of the pectoralis major muscle, and those on the side of the body from the arm-pit to the hip, also converge to the axilla. In regard to the two latter places, however, some of their absorb- ents, by penetrating the parietes of the thorax or abdomen, respec- tively join the internal absorbent trunks of these cavities. These several lymphatics from the upper extremity and from the trunk, traverse the axillary glands, and are successively re- duced in number to four or five voluminous trunks, which surround 314 CIRCULATORY SYSTEM. the subclavian artery. While in the axilla they are re-enforced by the deep lymphatics from beneath the pectoralis major, the latissimus dorsi, and the shoulder. Their number being again re- duced, they go along the subclavian vein over the first rib; those of the left side open either into the thoracic duct at its termination, or into the subclavian vein near it; but those on the right are finally assembled into the single large trunk, brachio-cephalic, which dis- charges into the angle of junction of the right internal jugular and subclavian vein. Absorbent Glands of the Upper Extremity. These glands are rarely found on the fore-arm, but when they do exist, it is in the course of the deep absorbents, and they are very small, and but few. From one to four are found scattered on the front of the elbow and internal condyle. From four to seven exist along the sheath of the brachial vessels and nerves. The axillary glands are very numerous, and of different sizes; they are dispersed throughout the cellular substance of the axilla, reposing on the serratus major anticus, between the pectoral mus- cles and those of the shoulder, and being, for the most part, below the axillary vessels and nerves, but some reposing immediately upon them, and forming a chain from the lower part of the axilla to the clavicle. Their number is from fifteen to thirty-five or forty. All the absorbents which observe the route of the axilla to reach the thoracic duct have to pass through these glands. SECT. III.--ABSORBENTS OF THE INFERIOR EXTREMITIES, AND OF THE CONTIGUOUS PARTS OF THE TRUNK OF THE BODY. The superficial absorbents, like those of the upper extremities, are placed between the skin and the aponeurosis, in the cellular tissue that contains the subcutaneous veins. They are also very abundant, and are found every few lines on the circumference of the limb; they are, however, more numerous internally than ex- ternally, and, for the most part, run upwards. Those on the inner or anterior side of the limb are first per- ceived on the back of the toes and foot. They incline over the ABSORBENTS OF THE INFERIOR EXTREMITIES. 315 front of the ankle, and its internal face to the inner side of the leg; they then ascend over the inner side of the knee, and along the same side of the thigh to the groin. The superficial absorbents of the back of the lower extremity are first perceived on the sole of the foot. They ascend along the back of the oilter ankle and of the leg above the knee; they then incline semi-spirally inwards, so as to bring themselves to the front of the thigh. These several ab- sorbents, though there are but few on the foot, augment continu- ally in number by new accessions in their ascent. All those on the posterior internal face of the thigh wind over its internal side, while such as are on its posterior external face wind over the outer side, to reach the inguinal glands. The Deep Absorbents adhere to the arteries, being at least two to each, and adopting the same distribution and nomenclature. The anterior tibial set begins in the sole of the foot, and rises to its back between the first two metatarsal bones; another branch begins on the dorsum of the foot. The first pursues the course of the an- terior tibial artery through the interosseal ligament to the ham, the second frequently joins the peroneal absorbents about half way up the leg. The posterior tibial and the peroneal absorbents, as they cruise along their respective arteries, do not require any farther comment. There is a fourth set of these deep absorbents, amount- ing to two or three in number, which attend the external saphena vein, and come from the external side of the foot. Getting between the heads of the gastrocnemii muscles, they are re-enforced by other trunks from this muscle; some of the branches then associate themselves with the superficial lymphatics, and others penetrate the ham, so as to join the deep trunks there. The deep absorbents of the leg coalesce partially in the ham, and ascend along the popliteal artery. On the thigh, there are from four to eight of these trunks attending the femoral artery, and receiving additions as the latter detaches branches. There are two or three lymphatic vessels on each side of the penis, which begin at its glans and prepuce, and traversing the length of this organ, wind above the external abdominal ring to join the nearest inguinal gland. There are several from the side of the scrotum and perineum, which ascend along the chord and thigh to join also the nearest inguinal gland. In the female, those 316 CIRCULATORY SYSTEM. of the labia externa and clitoris correspond with those of the scro- ■ ■ turn and penis. The superficial absorbent trunks, from the lower front of the : abdomen, are not numerous; they descend and converge also to > > the inguinal glands. Some of those from the loins, such as do not ascend to the axilla, advance to the inguinal glands. Those of the buttocks do the same. Absorbent Glands of the Lower Extremities. Absorbent Glands, below the knee, are not abundant, or, indeed, very common; yet, one or two exist sometimes in the course of the anterior tibial artery in the upper part of the leg. The popli- teal glands are three or four; they are small, and scattered at wide intervals in the fat of the ham around its vessels. From the latter to the groin, they are not usually found at all. The Inguinal Glands are amongst the largest in the system; they repose along the anterior margin of Poupart's ligament and a little below, and are readily felt beneath the skin. The superfi- cial vary in number, in different individuals, from seven to twenty, being more numerous as they are smaller, and are placed between the laminae of the fascia superficialis. They receive first of all, the superficial lymphatics of all the parts mentioned. The deep- seated are smaller, are a little lower down on the thigh, and lie along the course of the femoral artery, beneath the aponeurosis of the thigh; they are from three to seven in number, but are much less constant than the superficial. SECT. IV.—DEEP ABSORBENTS OF THE PELVIS. The Deep Asorbents of the parietes of the pelvis, as in other cases, attend the arteries of the part and have the same names. The obturators come from the heads of the adductor muscles, and, passing through the obturator foramen, end in the hypogas- tric glands. The ischiatics come from the small muscles on the back of the hip joint, and getting into the pelvis along with the sciatic artery, they also terminate in the hypogastric glands. The gluteals come from the three gluteal muscles, and entering the DEEP ABSORBENTS OF THE PELVIS. 317 pelvis along with the artery at the superior margin of the sciatic notch, they likewise terminate in the hypogastric glands along with some vessels from the anus and the perineum. The ilio-lumbar, the sacral, and the circumflex iliac absorbents, also follow their respective arteries and terminate in the nearest glands. The absorbents of the Testicle are numerous and large: accord- ing to Dr. W. Hunter,* they can sometimes be very completely injected by a pipe thrust into the substance of the testicle, and, according to Cruikshank,f very advantageously from the vas de- ferens, which has succeeded in my own hands. They form two layers, one superficial coming from the tunica vaginalis testis, and the other from the substance of the gland. They, finally, unite into some six or eight trunks, whichj ascend with the chord through the abdominal canal. Occasionally, one or more of them is as large as a crow-quill. By following the course of the sper- matic artery, they at last terminate in the lumbar glands. The deep absorbents of the Penis accompany the arteries, and, therefore, either get into the pelvis beneath the symphysis of the pubes, or along the crura and the tuberosities of the ischia; hence, a chancre on the prepuce causes bubo, while one on the glans very rarely does, and yet the constitution will be equally affected.§ These absorbents terminate in the hypogastric glands. The deep absorbents of the Clitoris follow, in the same way, the internal pudic artery. The absorbents of the Urinary Bladder are also numerous, and pass in several trunks from its sides to the hypogastric glands. Those of the prostate gland and vesiculae seminales are associated with them. The absorbents of the lower part of the vagina accompany the round ligament of the uterus through the abdominal canal, and, finally anastomose with those of the uterus. Those of the upper portion of the vagina are immediately associated with such as be- long to the uterus. The absorbents of the uterus are not so well seen in the un- impregnated state, but in impregnation they are so prodigiously numerous, that when injected with quicksilver, one is almost tempted to suppose that the uterus consists entirely of them. * Loc. cit. + Loc. cit. p. 155. X Mascagni, loc. cit. § Cruikshank, loc. cit. Vol. II.—28 318 CIRCULATORY SYSTEM. Mascagni's plate on this subject is an exquisite specimen.* As they all terminate in the hypogastric trunks, the latter are in such case as large as goose-quills.f The hypogastric plexus, from these several accessions from the parietes and viscera of the pelvis, becomes very large, and follows the course of the hypogastric artery in ascending into the loins. There are likewise some spermatic absorbents in the female, called so from attending the vessels of the same name. They come from the ovarium, the Fallopian tube, and the round liga- ment, to terminate in the lumbar glands; they anastomose below with those of the uterus. Of the Glands of the Pelvis. Some few glands lie beneath the gluteus maximus muscle, but the majority are within the pelvis. Those which are called the External Iliac are at least six, frequently more, and extend from Poupart's Ligament to the lower part of the loins, being planted along the external iliac artery, both above and below. The Hy- pogastric or Internal Iliac Glands are rather more numerous than the others, and form a chain along the hypogastric arterv. The latter are much disposed to form large indurated masses from dis- eases of the rectum, uterus, and bladder.J SECT. V.—ABSORBENTS OF THE ORGANS OF DIGESTION. The Absorbents of the Stomach are very numerous, and lie in two planes; one is superficial, being immediately beneath the peri- toneal coat, and the other is profound, being placed between the muscular and the mucous coat. They are, finally, assembled into three divisions, which follow the course of the principal blood ves- sels of this organ. One division, coming from the anterior and the posterior faces of the stomach, converges to its lesser curvature, and passes through some six or eight small glands in the adjacent portion of * Loc. cit. t Cruikshank, loc. cit. X Cruikshank, loc. cit. ABSORBENTS OF THE ORGANS OF DIGESTION. 319 the lesser omentum. Inclining to the right of the cardiac orifice, its trunks then pass through some glands common to them and to the deep lymphatics of the liver. Their numbers being reduced, they then descend behind the pancreas, and terminate in the thoracic duct near the cceliac artery. The second division comes from the left inferior portion of the stomach, and from its greater extremity, and, blending with the absorbents of the spleen and pancreas, goes with them into the thoracic duct. The third division comes from the right inferior portion of the stomach, and, assembling towards the pylorus, is subsequently mixed with some of the absorbents of the liver and of the small intestines, and goes along with them into the thoracic duct. The Absorbents of the Great Omentum join those of the stomach and of the colon, at the points most convenient to them. The Absorbents of the Small Intestines, like those of the stomach, are both superficial and deep, and from the function of convey- ing chyle, have been called lacteals, or chyliferous vessels. As the chyle, however, can only be absorbed by the deep ones; and, as they and the superficial have common trunks, as they also absorb, from the intestines, fluids not converted into chyle, there seems to be no necessity for distinguishing them by a particular epithet. The deep are in the cellular coat of the intestine, and follow the ramifications of the arteries, being double their number. The superficial, being immediately beneath the peritoneal coat, run for some distance, longitudinally, on the gut, and then turn off to the mesentery at right angles. On the mesentery these absorbents are not rigidly bound to the course of the blood vessels; they converge in a slightly tortuous manner from its circumference to its root. They anastomose with one another, by which their number is reduced; and they also have to pass through the series of mesenteric glands. The lac- teals of the duodenum and jejunum are larger and more numerous than those of the ileum, in the proportion of the greater extent of the internal surface of the former intestines, from the number of their valvulse conniventes. The vessels of the mesentery, after having cleared the. series of glands, and held some intercourse 320 CIRCULATORY SYSTEM. with the lymphatics of the spleen, liver, stomach, and pancreas, are reduced at last into one or more large trunks, which, ob- serving the course of the superior mesenteric artery, empty near the root of the latter, but sometimes lower down, into the thoracic duct. The absorbents of the Large Intestines are much less numerous than those of the small. They are also superficial and deep, and observe the course of the blood vessels. Those from the right portion and middle of the colon join the lacteals of the mesentery, while such as belong to the sigmoid flexure follow the inferior mesenteric artery up to the lumbar glands. Those of the rectum go partly into the lumbar and partly into the hypogastric glands, and as its blood vessels are more numerous than those of other portions of the large intestine, its absorbents are in the same pro- portion.* The Absorbents of the Liver are exceedingly numerous, and are also injected with unusual ease from the larger into the smaller trunks, from the imperfection of the valvular arrangements. They are also superficial and deep. The Superficial Absorbents of the upper surface of the liver run in several divisions, the number of which is unsettled. Those near the middle front of the liver assemble into six or more trunks, which ascend the suspensory ligament, and enter the thorax be- tween the diaphragm and the sternum. They are joined by seve- ral trunks from the diaphragm, and continuing to ascend up the anterior mediastinum between its laminae behind the sternum, they are re-enforced by contributions from the pericardium, from the thymus gland, and from the anterior parietes of the thorax. The division then crosses the upper end of the descending cava, and those from the two sides assembling, they go in one or more large trunks along the left vena innominata, and finally empty into the left thoracic duct near its termination. Sometimes they enter into the right thoracic duct. It occasionally happens that a detach- ment of this division, instead of ascending through the mediasti- num, is directed towards the coronary ligament of the liver; and Cruikshank, loc. cit. ABSORBENTS OF THE ORGANS OF DIGESTION. 321 being there joined by other vessels, it enters immediately into the thoracic duct at the upper part of the abdominal cavity, or at the lower part of the thorax. Another division comes from the upper surface of the right lobe, and gaining the right lateral ligament, penetrates into the thorax through the diaphragm, and advancing along the costal margin of this muscle, terminates in the first division under the sternum. Sometimes one of its branches, thrice as large as a crow-quill, runs backward to the spine, and is inserted into the thoracic duct behind the oesophagus, without passing through any gland; there are also, occasionally, several other arrangements of the trunks of this division.* Another division comes from the upper surface of the left lobe of the liver, and its trunks, advancing to the left lateral ligament, get into the thorax through the diaphragm. Some of the trunks- then run forward on the convexity of this muscle, to terminate in the trunks under the sternum, while others retire backward to end in the glands around the oesophagus, immediately above the dia- phragm. There are various departures from this general arrangement of the absorbents on the upper surface of the liver; as their trunks invariably reach the thoracic duct ultimately, the particular routes do not seem to be rigidly fixed. The Superficial Absorbents of the under surface of the liver present, also, diversities, but they are seldom arranged into so many divisions as those of the upper surface. They communi- cate freely with the latter, and also with the profound, and, finally, assembling in the transverse fissure, they descend along the capsule of Glisson to join and anastomose with the contigu- ous trunks from the alimentary canal, from the pancreas, and the spleen. The Deep Absorbents of the liver follow the branching of the vena portarum, and, emerging at the transverse fissure, pass through the glands in the capsule of Glisson, associating them- selves at the same time with the superficial trunks, and having a common termination with them. By putting a ligature around the * Cruikshank, loc. cit. 28* 322 CIRCULATORY SYSTEM. vena portarum of a living animal, many of them are included in it; they then become exceedingly turgid, and are seen to diverge through the liver like the pori biliarii. The liver is said to be more abundantly furnished with absor- bents than any other viscus. The Absorbents of the spleen are also superficial and deep-seated. The former are between the peritoneal and the proper coat, and are injected with some difficulty in the human subject, but are very demonstrable and numerous in the calf. The latter emerge at the fissure of the spleen, and, traversing the glands that lie along the course of the splenic artery, receive successively the absorbents from the pancreas. They, finally, end in the thoracic duct, after reciprocal junctions, and anastomose with the vessels from the stomach and liver. The Absorbents of the Pancreas are also numerous, and may be injected, contrary to their circulation, from those of the liver. They arise from the substance of the pancreas, like its vessels, by short trunks, which join those of the Splenic Plexus at right angles. The Absorbents of the Kidneys are superficial and deep; the former, though numerous, are too small in the healthy state of these organs to be well seen, but they become very distinct from disease, and converge from its periphery to its fissure. The deep absorbents accompany the vessels, and, emerging with them at the fissure, are joined with the superficial; they all then run along the emulgent vessels, and have frequent anastomoses with those of the testicles or ovaries, and with those of the capsular renales. These absorbents may be filled by putting a pipe into the excretory duct of the kidney. The absorbents of the Capsulae Renales unite to those from the kidneys, and, therefore, terminate with them in the lumbar glands. Of the Absorbent Glands of the Abdomen. The cavity of the abdomen contains many more glands than any other region of the body, on account of the very great extent ABSORBENTS OF THE ORGANS OF DIGESTION. 323 sion of the serous system in it, of the functions exercised by its viscera, and of its being traversed by the absorbents of the lower extremities. Many of these Glands have already been described under the denomination of hypogastric, and external iliac ; in addi- tion to which there are a few between the laminae of the meso- rectum in front of the sacrum. The Mesenteric Glands are exceedingly numerous, and amount to between one and two hundred ; they begin at an inch or two from the small intestines, and may be traced to the root of the mesentery, being placed between its layers, on the convex side of the upper mesenteric artery. As the intestinal canal is longer in some individuals than in others, they are proportionately more numerous. Their largest size seldom exceeds that of an almond: those belonging to the jejunum are rather more developed than such as belong to the ilium, and they all augment in size as they approach the root of the mesentery. The Glands of the Mesocolon are-placed between the laminae of this membrane, near the intestine; they receive the absorbents from the large intestines, are much smaller than those of the me- sentery, and their number seldom exceeds fifty. Some few of them are situated near the root of the mesocolon. They are by no means so disposed to tumefaction from scrofulous affections as those of the Mesentery. It is stated by Winslow, that he demon- strated to the Academy of Sciences at Paris, chyle in the absor- bents of the Mesocolon; this fact will assist us in accounting for the effects of nutritive glysters. The Gastro-Epiploic Glands are situated between the laminae of the omenta, where they join the curvatures of the stomach. Their number seldom exceeds four or five for each curvature, and they receive the lymphatics of the stomach and omenta. The Caeliac Glands are those which belong to the liver, the spleen, and the pancreas; they follow the course of the blood ves- sels of these organs, and are traversed by their absorbents. The trunk of the vena portarum is surrounded by them, and Mr. Cruik- shank says, that he has seen the biliary and pancreatic ducts in a state of compression from their tumefaction. 324 CIRCULATORY SYSTEM. The Lumbar Glands are very numerous and large; they are scattered over the whole region, from the base of the sacrum to the pillars of the diaphragm, lying on each side of the bodies of the lumbar vertebrae, and in front of the abdominal aorta and vena cava, being concealed by the root of the mesentery and of the mesocolon. They may be considered as continuations of all the preceding congeries of glands in the abdomen, and, therefore, when they, along with the vessels leading to them, are successfully injected, they form so thick a plexus of absorbents, reaching from the pelvis to the concavity of the diaphragm, that the great blood vessels can scarcely be seen for them. Many of the vessels reach- ing from one to another, are as large as a crow-quill. SECT. VI.—ABSORBENTS OF THE VISCERA OF THE THORAX. The Absorbents of the Lungs are thought to be next in abun- dance after those of the liver, and are likewise divided into two sets, the superficial and the deep-seated. The former are beneath the pleura pulmonalis. Mr. Cruikshank* says, that they are not always to be found, though commonly he has readily shown them covering with their meshes the whole external surface of the lung. The larger meshes follow the interstices of the lobules, and within them are others of extreme delicacy. The same author states, that one of the easiest methods of finding them, is to inflate the lungs of a still-born child, from the trachea, and the air in passing from its proper cells, will get into the absorbents; a puncture being then made into one of the latter, quicksilver may be very readilv introduced. Some of their trunks penetrate to the bottom of the fissures of the lungs, and pass through the glands there, while others continue more superficial along the internal face of the lung, and so reach the bronchial glands. The deep absorbents of the lungs observe the course of the pul- monary vessels and of the bronchia. They arise from the sub- stance of the lung, anastomose very freely with the superficial vessels, and, in parting from the lung, pass through the bronchial glands, where they are joined by the superficial. By the junction of the branches from the left lung, three consi- * Loc. cit., p. 194. ABSORBENTS OF THE VISCERA OF THE THORAX. 325 derable trunks are formed; one, which is sometimes the size of a goose-quill, is inserted into the thoracic duct, immediately behind the bifurcation of the trachea; another ascends between the trachea and the oesophagus, to join the thoracic duct near its termination, and the third joins the glands belonging to the absorbents of the heart.* The absorbents of.the right lung also coalesce into three princi- pal trunks at the root of the lung: one of them ascends across the front of the superior cava, making1, in its course, many elegant convolutions, and at length terminates in the second trunk on the left side.f The other trunks, ascending on the side of the trachea, and having traversed their glands, discharge into the right tho- racic or brachio-cephalic trunk, or else near it into the right in- ternal jugular, or into the right subclavian vein. There are,, in these respects, diversities in different subjects. The trunks of the Absorbents of the Heart follow the course of the coronary vessels, and distribute themselves by branches over its whole surface. They are, without previous management, easily discovered; but if the heart be macerated in water for several days, so as to become somewhat putrid, the absorbents are filled and distended by the gaseous exhalation: on the puncture of one of these vessels and the introduction of a pipe, they may all be readily filled. There are three principal trunks of these absorbents; one follows the right coronary artery to the root of the aorta, and then ascends over the front surface of the latter to the top of its arch, where it enters a gland. The other two trunks follow the two principal branches of the left coronary artery, and, coalescing near its origin, they ascend to the bifurcation of the pulmonary artery, and from that along the posterior face of the arch of the aorta, to enter a gland between it and the trachea. These several vessels subse- quently traverse the lymphatic glands about the trachea, common to the heart and to the lungs: and ultimately terminate under va- ried circumstances, either directly or indirectly, in the left thora- cic duct, the left internal jugular, or the left subclavian vein. Mr. Cruikshank says, that the right coronary trunk empties into the * Cruikshank, loc. cit. t Ibid. 326 CIRCULATORY SYSTEM. lymphatic trunks of the right side of the neck, which shows that there is no fixed arrangement. The Absorbents of the Pericardium may also be found; they, terminate like the others of the heart, in the bronchial glands, and are particularly associated with those of the thymus gland. The Absorbents of the (Esophagus are so numerous as to form a plexus from one end to the other of it. They run into the bron- chial glands, and, therefore, have a common termination with the absorbents of the heart and lungs. Mr. Cruikshank says, that he has reason to believe that he has seen life sustained through them alone and the absorbents of the mouth, in a case where stricture prevailed for some months just above the cardia, and where the food, after remaining for three or five minutes in the oesophagus, was vomited up.* The Absorbents of the Thymus Gland are very abundant in the infant, but diminish with the rest of the structure in the adult: they terminate in the bronchial glands also. SECT. VII.—ABSORBENTS OF THE PARIETES OF THE TRUNK. In addition to the absorbents mentioned as belonging to the in- ternal and external parietes of the pelvis, there are some others belonging to this cavity, as the ilio lumbar, the sacral, and the circumflex. The Ilio Lumbar Lymphatics come from the parts to which the artery of the same name is distributed, and, assembling into two or more large trunks which pass beneath the psoas magnus mus- cle, one of them joins the lumbar glands, and another the hypo- gastric. The Sacral Lymphatics arise from the cellular tissue in front of * A case somewhat similar occurred in the practice of Dr. Physick. ABSORBENTS OF THE PARIETES OF THE TRUNK. 327 the sacrum and from the spinal canal in the latter. Emerging through its foramina in front, they terminate in the lower part of the lumbar and in the hypogastric plexus. The Circumflex Iliac Lymphatics attending the artery of the same name, arise from the lateral inferior parietes of the abdo- men, in the thickness of its broad muscles; the several branches assemble into a few trunks, which descend along the posterior margin of Poupart's ligament to terminate in the external iliac plexus. The Epigastric Absorbents are derived from the inferior ante- rior parietes of the abdomen, along the region of distribution of the epigastric artery. Their trunks coalesce into larger ones, and descend along this artery to end in the external iliac plexus, near the crural arch. The Lumbar Absorbents arise from the muscles of the loins, from the posterior part of those of the abdomen, and from the spinal cavity. Their trunks correspond with the lumbar arteries, and passing beneath the psoas magnus muscle towards the spine, they terminate in the lumbar glands. The Intercostal Absorbents take their origin from the parietes of the thorax, and following the course of the respective intercostal arteries, pass through some small glands occasionally found be- tween the external intercostal muscles near the heads of the ribs. They are there joined by trunks from the spinal cavity and from the muscles of the back, and afterwards passing through some small glands on the front of the vertebral column, they anastomose more or less with one another, and finally terminate in the left tho- racic duct. The absorbents of the pleura costalis and of the pos- terior part of the pericardium terminate in the intercostals. The Internal Mammary Absorbents have their roots in the an- terior region of the parietes of the abdomen, above the umbilicus, where they anastomose with the epigastric. They ascend, along with the internal mammary arteries, behind the sternal cartilages, pass through some small glands, and receive contributions from the 328 CIRCULATORY SYSTEM. anterior extremities of the intercostal spaces. Those of the left side, assembling into one or two trunks, cross in front of the left sub- clavian vein, traverse the inferior cervical glands, descend after- wards from this point, and terminate in the left thoracic duct, or in one of the contiguous trunks of the venous system. Those on the right execute the same movements, but terminate in the right thoracic duct, or in one of the contiguous venous trunks on that side. The Absorbents of the Diaphragm are exceedingly numerous, and very much connected with those of the liver. The anterior ones join the internal mammary absorbents, while the posterior follow the phrenic arteries, or go to contiguous trunks belonging to the intercostals. The front ones on the right side, then termi- nate in the right thoracic duct, while the remainder go in the va- rious routes of the absorbents, with which they are connected, into the left thoracic duct. They are principally seen on its upper sur- face. Mr. Cruikshank* says, that he once saw them to the amount of three hundred or more, filled with chyle from the me- sentery that had passed through the substance of the liver. Asel- lius was, therefore, probably justified by an accident of this kind, in asserting that the lacteals went to the liver. The Absorbents of the Female Mammae, like their arteries and veins, are superficial and deep; the former attend the external tho- racic blood vessels, and the latter the internal mammary. The superficial arise from the circumference of the nipple, from the skin and cellular membrane, and according to the injections of Mr. Cruikshank, communicate freely with the vesicles of the tubuli lactiferi. They run towards the axilla, having occasionally to pass through some glands which are situated half way; they then enter the first series of glands of the axilla in their direction, and after- wards others successively, until they terminate in the lymphatic trunks of the upper extremity, high up in the arm-pit. Some few of these superficial vessels ascend over the pectoralis major to the glands in the neck, just above the clavicle* The deep absorbents of the mammae arise from their thoracic * Loc. cit. p, 90. THORACIC DUCTS. 329 face, and penetrating the intercostal spaces, join the absorbents that attend the internal mammary artery. Of the Absorbent Glands in the Thorax. There are, as mentioned, a few small glands in the intercostal spaces near the heads of the ribs between the internal and external intercostal muscles, intended to receive the lymphatics of these spaces. There are also several small ones situated on the front of the dorsal vertebrae, along the aorta and the oesophagus, in the posterior mediastinum. There are also from six to ten along the internal mammary artery; and some others in the anterior medias- tinum, along the sternal face of the pericardium. They are said to be very rarely affected by disease. The most considerable and striking glands in the thorax are those called Bronchial or Pulmonary, which receive the absorbents of the lungs. They cluster about the bifurcation of the trachea, and follow the bronchia for some distance into the substance of the lungs. They are from ten to twenty in number, and vary in size from an inch to a few lines in diameter. Till puberty they have a reddish colour, but afterwards they become gray, and finally black, following in these respects the change of colour in the lungs. According to Mr. Pearson, their complexion depends upon the deposite of pure carbon. In pulmonary consumption these glands are always enlarged, and look scrofulous. SECT. VIII.—OF THE THORACIC DUCTS. The Left Thoracic Duct (Ductus Thoracicus Sinister) is the main stream of the absorbent system to which almost all the others are but tributary, and by divers routes ultimately find their way into it. It begins about the second or third lumbar vertebra, in front of its body. Shortly after its commencement, while still in the abdomen, it suffers a dilatation more or less considerable, and varying in its shape in different subjects. This is called the Re- servoir of Pecquet, or the Receptaculum Chyli; the dilatation, Vol. II.—29 330 CIRCULATING SYSTEM. however, is frequently absent, and does not seem to be an essen- tial part of the structure: in our preparations at the University some have it, and others have it not. The thoracic duct enters the thorax between the crura of the diaphragm, to the right of, and behind the aorta; it then ascends on the front of the dorsal vertebrae, between the aorta and the vena azygos, in front of the right intercostal arteries, and behind the oesophagus. At the fourth dorsal vertebra it begins to incline in its ascent to the left side, and then ascends into the neck near the head of the first rib; it rises commonly as high up as the upper margin of the seventh cervical vertebra; it then turns downwards and forwards, over the left subclavian artery within the scaleni muscles, and, finally, discharges into the angle of junction of the left subclavian and internal jugular vein. The preceding is the most simple, and perhaps the most com- mon form, under which the thoracic duct is presented, but varieties are continually occurring in its place and mode of origin, in its trunk, and its manner and place of termination. It commonly begins by the union of three absorbent trunks ; one for each side of the pelvis, along with the corresponding lower extremity; and a middle one for the chyliferous vessels, which unites with the com- mon trunk of the other two, a few lines above its point of forma- tion ; on other occasions, the chyliferous trunks join it in a con- fused manner by nine or ten distinct channels. Sometimes an intricate plexus of several large trunks; derived from the lumbar and mesenteric glands, by the gradual reduction of the number of meshes from the successive joining of trunks; begins to assume, at the crura of the diaphragm, the form of a solitary trunk, which is the thoracic duct. The trunk of the duct is also disposed to keep up the anastomosing plan, even in the thorax; we hence see it sometimes dividing itself into two or three channels of equal size, which unite again after a shorter or longer distance, and perhaps in a little space repeat the same arrangement: sometimes a small arm is sent off, which runs along for an inch or two, and joins into the parent stream; sometimes spiral turns are adopted by the thoracic duct, sometimes nodosities, or small pouches are formed on its sides; sometimes it is dilated at intervals in its whole cir- cumference. Sometimes it splits into several channels at its ter- mination; one channel terminating in one vein and another in a THORACIC DUCTS. 331 contiguous one, of the several trunks forming the vena innominata; on other occasions, instead of entering into a venous trunk of the left side, it goes into the corresponding one of the right. Commonly, it is about the size of a large crow-quill, but some- times as large as a goose-quill, or even still more voluminous, seeming to be in a varicose state, of which Mr. Cruikshank men- tions an example where it was half an inch in diameter, and took two pounds of mercury to fill it. There is generally a pair of valves at the termination of the thoracic duct, or if it be divided into several streams there is a pair at the embouchure of each, to keep the venous blood out of it. There are also valves in its length, but they are not numerous, and vary in different subjects. The thoracic duct, as stated, is the grand outlet for the lym- phatics of the left side of the head and neck, of the left superior extremity, of the intercostal spaces, of the left side of the thorax, of the viscera of the abdomen, and of the inferior extremities. Though those of the viscera of the abdomen and of the lower ex- tremities have this route, yet, from the observations of Mr. Lippi, of Florence, as mentioned, they have also some more direct means of getting into the general circulation. For example he has found several large lymphatic trunks emptying into the ascending cava, one of them opposite the third lumbar vertebra; another into the primitive iliac vein: he has also found some of the lymphatics of the liver discharging into the vena portarum. The Right Thoracic Duct, (Ductus Thoracicus Dexter,) as it is called, but more properly the Right Brachio-cephalic, after the name given by M. Chaussier to the vein, is not more than an inch long, and descends to empty itself, as mentioned, into the junction of the right internal jugular with the right subclavian vein. It is derived from the lymphatic trunks of the right side of the head and neck, of the right upper extremity, the superficial lymphatics of the right side of the thorax, the lymphatics of the right lung, of the right side of the diaphragm, and some of those of the right side of the liver, the courses of all of which have been detailed. Though the single trunk is formed from these several tributary streams, yet the latter have sometimes several embouchures into the venous system at or near the point mentioned, and, as on the other side of the body, there is a proper security, by valves from the introduction of blood into them. 332 CIRCULATORY SYSTEM. There is always an ample system of anastomosis, not only be- tween the branches which concur to form the right and left tho- racic ducts, bot even between the ducts themselves,* so that if one be occluded or impeded, its circulation can be turned into the other, as in the case of veins. * Meckel, Man. D'Anat., torn, ii., p. 581. BOOK IX* PART I. OF THE GENERAL ANATOMY OP THE NERVOUS SYSTEM. Nervous System. The Essential ingredient of this System is a peculiar animal matter called Neurine, the texture of which is so soft, that in the natural state it has the least possible consistence. It is, therefore, protected in a variety of ways; by being enclosed in bone where it is collected in large masses, and by being surrounded by liga- mentous or cellular matter where flexure is required. The nervous system— 1. Arteria Lachrymalis arisesr commonly, soon after the oph- thalmic has got into the orbit: it goes forwards between the rectus superior and the rectus externus muscle, to which it distributes arterioles; it then reaches the lachrymal gland, and having left branches with it, what remains issues out at the external angle of the eye, so as to supply the contiguous part of the upper eyelid. 2. Arteries Ciliares. According to Soemmering, before the ori- tensions to its discovery and to attempt to remove such objections as required atten- tion. For the arguments on this subject, I refer to the Philadelphia Journal of Medical and Physical Sciences, of Nov., 1824, edited by Professor Chapman. My claims have been unequivocally admitted by Messrs. Breschetand Jourdan, of Paris, anatomists of unusual distinction, in the translation which they have made of J. F. Meckel's Manual of Anatomy, vol. iii., p. 219 ; by Gery,-in the Melanges de Chi- rurgie e"trangere, Geneva, 1824', p. 415; and by Professor Giuseppe Trasmondi, in the Arcadica Journal of Rome, &e. vol. xix., p. 1', 1823. At the date of the present, being my sixth edition, this muscle is admitted into the myology of the most classical works on Anatomy, the highest of whioh may be considered the latest edition of Soemmering, de Corp. Hum. Fabr., under the title of Encyclopedie Anatomique, Paris, 1843. 428 NERVOUS SYSTEM. gin of the lachrymal artery, the ophthalmic detaches from one to three ciliary, which penetrate into the ball of the eye near the optic nerve. Other arteries of the same class arise subsequently from the ophthalmic, and, occasionally some of them from the lachrymal itself. They go to the choroid coat of the eyeball and to the iris.. 3. The Arteria Centralis Retinae arises from among the cluster of ciliary arteries, and, like them, has no invariable root. It pene- trates the optic nerve about the middle of its orbitar portion, and, going in its centre, gets into the eye through the cribriform part of the sclerotica. It is then distributed by ramuscles to the retina, to the tunica hyaloidea, and to the capsule of the lens. 4. The Arteria Ethmoidea Posterior is inconstant in existence, and comes at one time from the trunk, at another from a branch of the ophthalmic. It passes over the superior oblique muscle, and penetrating through the posterior orbitary foramen, is spent by arterioles upon the neighbouring part of the dura mater, and upon the posterior ethmoidal cells, where it anastomoses upon the Schneiderian membrane, with branches from the internal max- illary. 5. Arteriae Musculares. Of these there are two; one of them, the inferior, sends branches to the rectus internus, rectus inferior, and obliquus inferior oculi; also to the lachrymal' sac, and to the parts about the bottom of the orbit. It occasionally detaches some of the ciliary arteries. The superior muscular branch is also called the Supra Orbitar. It supplies the muscles of the supe- rior part of the orbit, and then issuing through the supra orbitary foramen, it is spent in arterioles, upon the os frontis and its peri- osteum, and upon the orbicularis oculi, corrugator supercilii, and occipito-frontalis. It anastomoses there with other branches of the ophthalmic, and with the temporal artery. It is usual for the anterior ciliary arteries to come from the muscular branches. The Ophthalmic Artery, after having detached all the aforesaid THE EYE. 429 branches, is much diminished-in volume, andr. advancing along the internal parts of the;orbit,.its next branch is— 6. The Arteria Ethmoidea Anterior, which dips into the ante- rior internal orbitary foramen, and is divided into small branches, some of whioh are spent upon the adjacent portion of the dura mater, others upon the frontal sinus and the anterior ethmoidal cells. Some of these branches penetrate from the cranium through the cribriform plate into the nose, and, ramifying upon the Schnei- derian membrane, anastomose with the internal maxillary. 7. The Arteriae Palpebrals are two in number: they come sometimes from a common trunk, and on other occasions arise separately. One is the Superior, and the other the Inferior. The latter arises first, and is distributed to the conjunctiva, the carun- cula lachrymalis, lachrymal sac; and finishes by, many small branches to the lowereyelid, that anastomose with the infra-orbitar artery, so as to form the lower tarsal arch. It also anastomoses with the lachrymal artery by its extreme branches. The Superior Palpebral Artery also distributes branches to the conjunctiva, sac, and caruncle; it then emerges above the inner palpebral ligament, around the margin of the superior eyelid, and forms, along with the lachrymal and the supra orbitar artery, the superior tarsal arch* which distributes small branches, in great profusion, to the orbicularis muscle, and to the structure, generally, of the lid. It anastomoses, externally, with the lower palpebral artery. 8. The Arteria Nasalis is sometimes awell marked continuation of the ophthalmic. It passes out of the orbit at its internal can- thus, above the internal palpebral ligament, and anastomoses at the root of the nose with the facial artery. It is distributed to the side of the nose, and .to the lower part of the forehead. Its chief contribution to the eyelids is at the internal end of,the orbicularis, where it anastomoses with the palpebral arteries. 9. The Arteria Frontalis passes out of the orbit near the supra orbitary foramen. It is quickly divided into branches, which go 37* 430 NERVOUS SYSTEM. to the orbicularis and corrugator muscle, to the occipito-frontalis, and to the frontal-sinus. % Of the Veins of the Orbit. The blood distributed to the eye-ball and to its auxiliary parts, has two routes for returning to the heart, one through the caver- nous sinus, and the other by the superficial veins of the face. As a general rule, all the branches of the ophthalmic artery which reach the eyelids, or become otherwise superficial, return their blood by the latter route; and those whose distribution is to the ball of the eye and' to the parts deeply seated in the orbit, return their blood by the sinus. When the veins are well injected, a very considerable number is manifested in both eyelids. They form a handsome net-work, the meshes of which are small and numerous, and commence by small roots at the margin of the eyelids. The vessels of this net- work becoming, successively, larger from the centre to the cir- cumference of the orbicularis, cover the whole surface of the latter, and from the thinness of the skin are readily seen beneath it. The veins of the lower eye-lid are discharged into the facial vein, where it borders on the orbicularis; and the veins of the upper lid, being bordered along the superior margin of the orbicularis by a horizontal branch of the temporal vein, discharge themselves into it. The Ophthalmic Vein (Sinus Ophthalmicus) is the large trunk within the orbit which receives, successively, the remaining blood of the eye, and passing along the internal parts of the orbit, crosses over the optic nerve, and penetrates through the optic foramen into the cavity of the cranium, where it terminates in the caver- nous sinus. It may be considered as commencing by an anasto- mosis with the facial vein at the internal canthus; it then receives the following branches:— 1. The nasal, which arises from the parts about the internal canthus of the eye. 2. The anterior ethmoidal, which comes from the nose and frontal sinus. 3. Branches from the recti and obliqui muscles. THE BALL OF THE EYE. 431 4. The lachrymal vein, from the lachrymal gland and levator palpebrae muscle. 5. Posterior ethmoidal vein, from the nose. 6. The ciliary veins, or those of the choroid coat, which are very numerous. 7. Tbe central vein of the retina, which is collected from three or four principal branches, and follows the course of the artery of the same name, through the cribriform part of the sclerotic coat, and through the centre of the optic nerve. The trunks of this vein anastomose,, at the anterior margin of the retina, with those of the Ciliary Body. There are, of course,, frequent anastomoses between the veins of the eyelids and the primitive branches of the ophthalmic vein. SECT. II.--OF THE BALL OF THE EYE. The Eye-ball (Bulbus Oculi) is situated within the anterior half- of the orbit, from which it is kept separated by its auxiliary parts, and by a large quantity of adipose matter which fills up their in- terstices. It is very nearly spherical, but not so much so as to prevent its antero-posterior diameter, which is about an inch long, from exceeding in measurement every other. Such, at least, is the general opinion of anatomists, but from experiments, made by distending the eye with mercury, I have been induced to doubt its correctness, and especially in the African -r for, in the latter, I have uniformly found the transverse diameter to exceed the antero- posterior by a line or more. The Eye-ball is also somewhat flat- tened at the insertion of each of the straight muscles. . It is formed by a series of concentric tunics, one investing the other, and by humours contained within those tunics. Of the former, the Sclerotica-and the Cornea are external, the Choroidea and the Iris next, and the Retina is internal. Of the Humours, the Vitreous is, by far, the most abundant, and constitutes a prin- cipal part of the eye-ball; the Crystalline Humour is in front of the vitreous; and the Aqueous is placed between the crystalline) and the cornea. 432 NERVOUS SYSTEM. Tunics, or Membranes of the Eye-ball. The Sclerotic Coat (Tunica Sclerotica, Albuginea) forms about five-sixths of the exterior investment of the eye-ball, the remaining sixth of which is obtained from the cornea. At its posterior part it is joined by the optic nerve: this junction does not occur pre- cisely at its axis or centre, but at the inner side of it. When the optic nerve is detached at this junction, a small round hole is per- ceptible in the sclerotica, or, rather, it is more frequently perceived as a thin cribriform lamella, through the holes of which the pulpy part of the optic nerve passes, so as to get within the eye. This cribriform lamella, or the appearance of it, is no doubt produced artificially by the nerve being commonly cut through very near the eye; and, as Mr. Jacobs, of Dublin, very properly suggests, should be considered as the most anterior termination, or the point of the optic nerve instead of as a portion of the sclerotica. The neurileme of the optic nerve, is so arranged, that small round longitudinal canals are left, which contain the nervous matter: from this causeJt happens that a thin section of the optic nerve in any part of its course in the orbit, will, if held up to the light, manifest the same cribriform arrangement with the part alluded to. This part of the structure of the optic nerve will be readily understood by the American student, in comparing it with the pith of the Indian corn-stalk, which, being traversed longitudinally, by many fibres, upon the drawing of them out, an equal number of longitudinal canals is left in their places. At its fore part, the edge of the sclerotica is bevelled all around for its junction with the cornea; and though nearly circular, is not completely so, from its horizontal diameter being somewhat greater than any other. There are several orifices of inconsidera- ble size scattered over the sclerotica, some of which are oblique and others direct: they transmit the blood vessels and nerves.. The Sclerotica is nearly a line in thickness at its back, part, from which it gradually becomes reduced to half that thickness in front, where it is strengthened by the tendinous insertions of the recti muscles. Its internal surface is smooth and somewhat shining, being loosely attached to the cellular substance intervening be- tween it and the choroid coat; but the external surface is rough, and more obviously fibrous, and is attached somewhat strongly to THE BALL OF THE EYE. 433 all the adjoining parts by the cellular substance latterly called the sclerotic fascia. - The sclerotica is of a white colour, and consists of a single layer, whose structure is essentially fibrous. The fibres are very closely compacted, and compose an intertexture which cannot be unravelled. It is so firmly united to the dura mater covering of the optic nerve, that many anatomists, notwithstanding its greater thickness, are disposed to speak of it as a continuation of the same. Its strength and its want of elasticity suit it remarkably to maintain the form of the eye, and to resist injuries. Out of the many blood vessels that penetrate it, but few ramify in its struc- ture, and the existence of nerves in it is by no means evident. The tunica arachnoidea follows the course of the optic nerve, within its coat of dura mater, and forms, in the eye, just around the cribriform plate, or foramen of the sclerotica, a circular pad: it is then reflected on the internal face of the sclerotica, as far as its anterior edge. It is this which causes the internal face of the sclerotica to be smooth and shining, and thereby to correspond with that of the dura mater.* This circumstance is more readily proved in a very young eye, than in the adult one. The Cornea, as mentioned, fills up the aperture at the fore part of the sclerotica, and, of course, has the same diameters, with this opening; measuring thereby more transversely than in any other direction. It is a segment of a smaller sphere than the sclerotica^ and is, consequently, more convex than it. Its thickness is uni- form, and commonly exceeds that of the sclerotica at the fore part. of the latter. Its circumference adheres very closely to the sclerotica, and presents a bevelled or oblique edge, which is inserted into the cor- responding bevel of the sclerotica, so that the latter includes the former. The closeness of this junction induced the older anato- mists to consider these membranes as one and the same, notwith- standing their obvious difference of structure and of properties. Their adhesion yields to protracted maceration. The cornea is covered in front by a continuation of the tunica conjunctiva, which unites the eye-ball to the eye-lids. This may be proved by dissec- tion, by maceration, and by its sloughing off entirely along with * J. F. Meckel. Zinn supposed this surface to be derived from the pia mater. 434 NERVOUS SYSTEM. the epidermis of animals that are subject to this process, as the locust, snakes, and others. On its posterior faee, it is covered by the membrane of the aqueous humour, which may be rendered evident by steeping it in spirits of wine; whereby the latter mem- brane is made more hard, and may be thus torn off. This cap- sule of the aqueous humour differs decidedly from the cornea in not being made so opaque by the immersion in spirits of wine, we may hence infer the want of an albuminous constituent in it. The cornea, in a natural state, is perfectly transparent, and readily transmits the rays of light. It is of a fibrous structure, rendered very evident by steeping it in alcohol, and consists of an indefinite number of laminae, which are placed one against the other like the leaves of a book; they are united by a delicate trans- parent cellular substance which permits the laminae to slide upon each other. These laminae are kept moist and pellucid by an in- terstitial secretion of a fluid equally pellucid with themselves, the abundance of which in health gives to the eye its brilliancy, and the deficiency of it in illness and in death causes the eye to look dim and somewhat opaque. Its evaporation, which no doubt is continually occurring, is as constantly supplied by a fresh and abundant secretion. The motion of the eye-lids sweeps the resi- duum, after the evaporation of its watery particles, from the sur- face of the cornea: without this process, the residuum appears as- a thin layer or film of albuminous matter spread over the cornea when the eye is kept open without winking for a considerable time. The cornea has not at first sight the same strong unyielding struc- ture with the sclerotica, yet the application of mechanical force to the eye-ball shows that it is stronger. Neither has it vessels, con- veying red blood naturally, yet, in a state of inflammation, its capillaries dilate so as to admit red blood, and deposite coagulating lymph between its layers. It is common for anatomists to attri- bute a want of sensibility to it in a natural state: as a general rule, this is fallacious; for many persons, where the eyes are not inflamed, suffer extremely from its being cut in cataract, and some- times faint from the pain; while others are truly unconscious of the incisions made through it. For this opinion, I have had a full assurance from repeated observations on the practice of Dr. Phy- sick, as well as from instances in my own handis. THE BALL OF THE EYE. 435 Some anatomists, as Schlemm, claim to have traced branches of the ciliary nerves into the cornea.* This is denied by Arnold. The difference of actual texture between the cornea and the sclerotica is very inconsiderable; we are commonly misled by the transparency of the cornea, but if the albumen in it be coagulated by alcohol or neutral salts, the filaments of the two are identical in appearance. Dr. Arnold considers both to be formed of cellular substance permeated by an extremely fine close set of lymphatics,f an idea originating with Mascagni and applied by him to every tissue of the body. If a minute injection be successfully thrown into the conjunc- tival blood vessels of an infant, a beautiful vascular corona is formed at the anterior margin of the sclerotica. Professor Roemer, of Vienna, considers it to consist of two layers, a super- ficial derived from the lachrymal and palpebral, and a deeper one from the muscular and ciliary arteries. From this corona the surface of the cornea is supplied, and also its substance by con- verging branches. The Choroid Coat (Tunica Choroidea, Vasculosa,) is placed im- mediately within the circumference of the sclerotica, and is of equal extent. At its posterior part it furnishes, for the passage of the optic nerve, a single annular opening, the margin of which is somewhat thickened, and perfectly distinct from the pia mater in- vestment of the nerve, from which some anatomists have desired to trace this coat. The anterior opening of the choroid is bounded by the ciliary ligament and by the iris. On its outer side may be seen an abundance of loose flocculent cellular substance which joins it to the sclerotica. Internally, it is spread over the retina, but does not adhere to it. The choroid coat is closely fastened, at its anterior margin, to the corresponding part of the sclerotica, by a ring which surrounds it, of a short compact cellular tissue. This ring, called the Ciliary Ligament, (Ligamentum Ciliare, Orbiculus Ciliaris,) is from a line to two lines in breadth, and may be readily distinguished by its whiteness, contrasted with the dark colour of the choroid. It is intimately united to the latter, and seems to form a part of its structure, whereby it is caused to detach itself entirely from the sclerotica, and to adhere, by preference, to the choroid when these * Lawrence on Eye, p. 21. London, 1841. + Ibid. p. 14. 436 NERVOUS SYSTEM. two membranes are separated.* The iris is set in the front mar- gin of the ciliary ligament, so that the sclerotica and the cornea may be peeled from the choroidea and iris, without impairing the continuity of the two latter. Just beyond the junction of the two last, the ligament presents a small ridge or elevation all around, which is fitted into a corresponding fossa at the circumference of the posterior face of the cornea. The internal face of the choroid coat, as well as its anterior mar- gin, undergoes a very remarkable change from the general plan of this tunic, by forming what is called the Ciliary Body, (Corpus Ciliare, Corona Ciliaris.) In order to see this in the most favour- able manner, the eye should be laid on the cornea, and its posterior half cut away. It will then be evident, that just behind the iris, and within the circumference of the ciliary ligament, the internal face of the choroid coat forms a considerable number of radiated folds or little ridges, which converge from behind forwards and inwards. These folds commence by striae, almost imperceptible to the naked eye, which are in contact with the fore part of the vitreous humour, and with the canal of Petit, and thereby not only impress the neighbouring portion of the tunica hyaloidea with their shape, but even leave upon it the black pigment with which they themselves are covered. These folds, when they get near the cir- cumference of the iris, coalesce one with another, and terminate in a considerable number (from fifty to sixty, according to Soem- mering,) of processes, (Processus" Ciliares,) the central extremities of which are loose, and float in the aqueous humour. Some of these processes are longer than others. As a whole the ciliary processes constitute a ring of radiating filaments, which are a line or more in length, placed along side of, and in contact with, one another; the external periphery of the ring adheres to the ciliary ligament, and through it to the greater circumference of the iris, so that the ring appears, but fallaciously, to be continuous with the iris. In certain animals, as the sheep, the radiated appearance of the iris, on its posterior face, favours this notion still more. The internal periphery of the ring presents the central ends of the fila- * Fontana asserted, from seeing it in an ox, that a circular canal was to be found in this ligament; many examiners have failed in finding it, and its existence is de- nied by Arnold, who states it to be a venous tube in the thickness of the sclerotica for receiving the veins of the Iris, and called by him Circulus Venosus Iridis. It cannot be injected except from the arteries, THE BALL OF THE EYE. 437 ments detached from one another, and of a downy appearance; with the handle of a knife they may be readily pushed backwards and forwards. Generally speaking, the ciliary processes are so much concealed by the iris, that they cannot be seen in the living body through the cornea: in cases, however, of extreme dilatation of the pupil by narcotic applications, their central extremities are brought into view. The choroid coat always appears, when uninjected, of a very dark brown or black colour, arising from a black paint (Pigmen- tum Nigrum) being very thickly spread over the whole of that sur- face of it which is adjacent to the retina, and being also diffused through its thickness. This paint is more abundant near the iris than posteriorly, being laid on there in flakes, in the intervals be- tween the ciliary striae, and tinging also the ciliary processes. It may be removed in a considerable degree, indeed almost entirely, by maceration, or by careful washing with a camel's-hair pencil. It is supposed to be an exhalation from the vessels. This pigment of the choroid coat is contained in very fine cells, of a hexagonal shape, and making a continuous membrane from their abundance. Its particular colour is of a most durable kind. According to the observations of Bichat, the long-continued action of light upon it, when this pigment is transferred from the choroid to a piece of paper, does not affect it; neither is it changed by being submitted to very strong chemical agents, as sulphuric, muriatic, or nitric acid, alcohol, or caustic potash. This degree of indestructibility of colour is an invaluable property, and almost singular; for it is well known to the keepers of medicinal articles, that the colours of all of them yield to the continued influence of light, and that they also become weaker by the same cause. This indestructibi- lity by light, continues so long as the dry state is observed. A human choroid kept in alcohol and exposed to light, I have generally found to turn white in a series of years; in the sheep and bullock it is not so. In regatd to structure, the choroid coat is thin, soft and easily lacerated : when cleared of its pigment by maceration, it is semi- transparent, and is then seen evidently to consist of but one lami- na ; unless we may be disposed to consider as a second one the pigment, naturally on its internal face. It has no appearance of fibres in its composition, but, when injected, seems to consist al- most wholly of arteries and of veins. Vol. 11.-08 438 NERVOUS SYSTEM. The arteries are branches of the ophthalmic, and are called oiliary. There are two Long Ciliary Arteries, which penetrate the sclerotic coat not far from the optic nerve, and pass, one of them, on the external and superior part of the choroides, and the other on its inferior and nasal side, to the front of the eye. In this course, they do not send off any branches of consequence till they reach the iris, upon which they are distributed. The Short Ciliary Arteries are much more numerous than the others, and also smaller; their number sometimes amount's to twenty; the most of them penetrate the sclerotica from behind, near the optic nerve also.* They quickly divide into a great number of branches, which de- part at very acute angles, and have frequent anastomoses with one another. These branches run forwards, nearly parallel, and at the fore part of the choroides, form a very intricate intertexture, which is continued upon the ciliary processes, and communicates with the vessels of the iris.| The yeins of the choroid coat are also extremely abundant. They run from before backwards, and the branches which concur to form them, being adjacent with, and parallel to each other, for the most part, form large curves, the convexity of which is for- wards; they, moreover, anastomose freely, and thereby produce a vascular sort of net-work, filling up the concavity of some of the curves. These veins, called the Vasa Vorticosa, are nearer the external surface of the choroides than the arteries, and are assem- bled into twelve or fourteen trunks, which, engaging in the sclero- tica, near its middle, run for some distance in its substance, and then, by their junction, are reduced to four or five in number. The latter, disengaging themselves from the eye, join, subsequently, the ophthalmic vein. In addition to the veins mentioned, the long ciliary arteries have their venae comites, which take a course parallel to and adjoining them. These veins do not observe the vortical arrangement of the others; they bring back the blood of the iris, and terminate in the larger trunks of the others. This structure has been most cautiously explored by the cele- brated Soemmering, and his observations have te ded very much to determine the opinions of anatomists concerning many parts of the eye. A curious remark of his is, that " the human eye may be * Soemmering, Icones Oculi Humani. t Icones Oculi Humani. THE BALL OF THE EYE. 439 distinguished from that of animals by a form of this vascular net work, entirely peculiar; for example, in the eye of the ape, its vas- cular tissue differs not only from that of the human subject, but also from that of the dog, and still more evidently from that of the calf. From which cause, it would be as easy to distinguish with a microscope, the choroides, well injected, of different animals, even a piece of only the forty-eighth part of an inch in extent, as it is easy to distinguish a poplar stripped of its leaves from an oak, a pear tree, an apple tree, or any other tree-, by the arrangement of its trunk and branches. The choroides, on its internal face, is not smooth, but velvety, which becomes still more conspicuous when the eye is finely in- jected and examined with a microscope. Meckel considers the appearance to depend upon its very fine tissue of vessels. This surface is called Tapetum. In the bullock, and some other ani- mals, at a particular part, it presents a shining, silvery appear- ance, and may be torn off from the external surface. Ruysch attributed two laminae to the choroid membrane in the human sub- ject, the internal of which was called after his name, but the dis- tinction is now generally abandoned. The Iris is a circular plane placed at the front of the choroides, and having, in its centre, a round opening called the pupil (pupilla.) Its external circumference as stated is attached to the ciliary liga- ment, and by it to the choroid coat, and is exactly at the junction of the cornea with the sclerotica. Professor Soemmering has be- stowed much attention in ascertaining whether this membrane is perfectly flat or somewhat convex in front, and, by repeated ob- servations, carefully made, has assured himself that it is flat.* My own observations and preparations have induced me to believe that in many cases it will be found slightly convex in front, as Petit asserted more than a century ago. In a moderate state of dilatation, its nasal or internal border is somewhat narrower than its external or temporal. With the exception of its external cir- cumference, every part of the iris is devoid of any attachment; by which arrangement it moves freely in the aqueous humour, so as to contract or dilate the pupil, according to the quantity of light admitted upon the eye. * Icones Oculi Humani. 440 NERVOUS SYSTEM. The iris, with the exception of its central or pupillary circum- ference, where it is thinner than elsewhere, is much thicker than the choroid coat. The posterior face of the iris, sometimes called uvea, is covered in great abundance with pigmentum nigrum. When this is removed by maceration, which may be readily done, the membrane becomes semi-transparent. Its anterior surface is the seat ofcthe colour, which characterizes every individual's eyes. There are but two of these colours, light blue and orange, the predominance of one or the other of which, assisted by the dark ground on the back of the iris, gives the cast of hue to the eye. The front surface, when examined on the living eye with the microscope, is seen to be downy or flocculent, and is traversed by filaments forming an intertexture, some of which are circular, others oblique; and others radiated. This arrangement is remark- ably distinct in the eye of the seal. The power which the iris has of dilating the pupil when there is but little light, and of contracting it when there is much, has induced many anatomists to think that it is formed of muscular radiated fibres, which by their contraction produce the first mo- tion, and of circular ones which produce the last. Among these anatomists may be mentioned, Ruysch, Morgagni, Zinn, Sabatier. Ruysch asserted that the radiated fibres extended from the greater circumference of the iris to the pupil, and were fixed there by very delicate tendons. The late Doctor Monro, of Edinburgh, has de- scribed particularly the circular fibres, and a preparation of the bullock's eye which belonged to him is still exhibited there, where these fibres are found around the margin of the pupil. The several fibres can only be seen distinctly, when the pigmentum nigrum is washed away. Demours and Meckel deny the existence of the radiated fibres. The late distinguished Professor Wistar taught that the contraction of the pupil was produced by circular fibres, and the dilatation of it by its elasticity. In objection to this, the late Dr. Physick remarks, that as elasticity is as much a property of dead as of living matter; in death, therefore, we should always find the pupil dilated from the want of active contraction in the circular fibres; also, in cases of concussion of the brain, where there is a sudden loss of sensibility and of muscular motion, the pupil should be invariably dilated; but the fact is, that the pupil remains just in the same state that it was at the moment of the THE BALL OF THE EYE. 441 accident.* The distinguished anatomist, Arnold, has after very careful inquiry come to the conclusion that the Iris is formed of numerous blood vessels, of many nerves and of cellular substance. Notwithstanding the extreme sensibility and mobility of the iris on the admission of light, one is occasionally astonished to find it not contracting when instruments are applied to it, as I have had an opportunity of twice observing, upon the removal of a con- siderable portion of it, in making an artificial pupil for opacity of the cornea. In these cases, upon the letting out of the aqueous humour, it became quite as flaccid as we are accustomed to see it in our dissections.. The same remark has been made by the late Sir Charles Bell. The Blood Vessels of the Iris are principally branches of the Long Ciliary, which have been alluded to. Each of the two Long Ciliary Arteries having gained the greater circumference of the iris, bifurcates; the bifurcation runs along this circumference, meets, and joins with the corresponding one of the other arterial trunk. From the circle thus formed there proceed radiated branches, that run towards the pupil, and form around its margin, by their frequent anastomoses-, a fine vascular net-work. The radiated branches themselves give off collateral branches, which supply the intermediate spaces of the iris.f The veins of the iris are also numerous, but cannot be quite so distinctly seen: they enter into the long ciliary veins, and also into the vasa vorticosa. The nerves of the Iris belong, in part, also to the choroid coat, and are classed under the term Ciliary, (Nervi Ciliares.) They arise from the ophthalmic ganglion, and from the trunks contri- buting thereto, and are about twenty in number- They penetrate the posterior part of the sclerotica obliquely, and then run forwards between it and the choroides* Having reached the posterior paft of the ciliary ligament, they penetrate it, and distribute their fila- ments in its substance, after the same fashion that the trigeminus nerve is divided in its ganglion. This circumstance has given occasion to Soemmering to consider the ligament as a true gan- glion, and to call it Annulus Gangliformis. The nerves then get to the front of the iris, and are there distributed as white radiating * It is asserted that the question of the muscularity of the iris has been settled almost conclusively by Mr. Bauer. See Ph. Trans, for 1822. t Soemmering, Icones Oculi Humani. 38* 442. NERVOUS SYSTEM. filaments; in the course of which may be observed small nodes, supposed by Meckel to be Ganglions. The trunks of the ciliary nerves depart from the common form of such bodies, by being flattened instead of cylindrical: they are small, and resemble sewing threads. From their number, the iris is probably more abundantly supplied with nerves than any other organ of the body. The Retina forms the third coat of the eye, and lines the internal face of the choroides almost in its whole extent. The optic nerve having passed through the sclerotica, terminates on its inner side by a bulb or button-like end, from the circumference of which the retina begins to expand, and may be traced satisfactorily as far as the commencement of the ciliary plaits of the choroid coat, where it terminates by a straight edge, somewhat thickened. Just at the edge, the retina adheres to the vitreous humour, and is supposed, erroneously by some anatomists, as Bichat and Monro, to be con- tinued on to the circumference of the lens. Repeated dissections, and the substantial testimony of Soemmering,* have satisfied me that the retina cannot be fairly traced beyond the greater circum- ference of the impressions made on the vitreous humour by the ciliary striae of the Choroides. When the eye is slightly macerated, the retina always parts from the vitreous humour at this line; moreover, when its structure is still more slightly changed by freezing and then thawing, the retina manifests a decided pre- ference to separate there, and, under the most careful dissection, it is very difficult to prevent it. In addition to these considera- tions, there is a well marked change of colour at the line men- tioned : in front of this line, the surface is transparent when cleaned from the pigmentum nigrum; whereas, if it were retina, it should be the colour of ground glass, as is usual in the dead body: also the veins of the retina never trespass beyond this line, but are seen to cruise along it. Most anatomists teach that the retina is an expansion of the optic nerve. Bichat believed that the latter terminated at the bulb, and that the retina was another part of the structure, but still consisting of the same sort of nervous matter. The latter opinion is probably the more strictly correct, because there is more pulpy * Icones Oculi Humani. THE BALL OF THE EYE. 443 matter in a section of the retina than can be found in the same length of the optic nerve; also, if the retina were simply an ex- pansion of the nerve without any addition of matter to it, it should, from its hollow globular shape, be thinner in the middle, where it is most expanded, than it is where the expansion first begins at the bulb of the optic nerve, but this is not the case. The retina does not adhere to the choroid coat, neither to the vitreous humour which it encloses, except at the line mentioned: when this line of attachment is broken, the retina quickly col- lapses. The texture of the retina is extremely soft and pulpy; in the living state, it is probably nearly transparent, but this can only be conjectured from the readiness with which the vessels of the cho- roid coat can be seen in animals destitute of pigmentum nigrum. It is composed of two laminae, of which the external is nervous, and the internal, or that next to the vitreous humour, is formed of a fine reticulated cellular membrane with blood vessels running through it. The external lamina may be removed by a camel's hair-pencil, or by slight putrefaction and washing, so as to leave the internal entire. The celebrated John Hunter succeeded, how- ever, in separating the two laminae fairly from each other, and preserving them, so as to show their difference. This specimen may be considered unique, and every way deserving of the source from which it proceeded.* Exactly in the axis of the eye, or at its centre, posteriorly, con- * The fact was communicated to me by the late Dr. Physick, who studied under Mr. Hunter, and frequently saw the preparation. The Retina is said by Langcnback to have three coats. 1st. An external granular coat. 2. Ehrcnberg's filamentous nervous coat: and 3d..A vascular coat,consisting of blood vessels, united into a delicate membrane by much cellular substance. Whether the filaments of the nervous coat be plain cylindrical, or nodulated ones, is unsettled. The granular layer terminates at the macula flava by a sharp edge; and it ends also at the border of the ciliary ligament. Treviranus, also, admits the division of the optic nerve into cylinders, and of extreme minuteness. The granular layer is said by Gottshe not to be found in recent eyes; he also says that, a per- fectly recent retina has the appearance of a thatched roof; that is little cylinders, the ends of which project out, like a 6taff. Michaelis admits the division of the retina into three layers, as above, and adds a fourth, it being the tunica Jacobi. The internal layer he considers as serous. The fasciculi of the nervous coat are best shown by means of the spirit of creosote. The filaments he estimates at a diameter of the Wpij °f a 'me# The serous coat is test seen by the use of diluted sulphuric acid. Mailer's Report on Nervous System, p. 237. 444 NERVOUS SYSTEM. sequently, about a line and a-half from the outer side of the bulb of the optic nerve, Soemmering* discovered a yellow spot (Macula flava) of a line in diameter, with a small hole in its middle, made by a deficiency of nervous matter. From the optic nerve there goes, towards the foramen, a small fold of the retina, pointed at its internal end, and obtuse or bifurcated externally. Unless the eye be fresh, these things cannot be seen distinctly, for the evapo- ration of the aqueous humour causes a collapse or wrinkling of the retina, which obscures them. But, in a perfectly fresh eye, which is well managed, they may be seen both from before and behind. It was thought, for some time, that the yellow spot and the fora- men were peculiar attributes of the human being : more extended and successful observation has corrected this mistake, by detecting them in several classes of animals.f In the centre of the optic nerve, where it enters the eye, is a foramen for the passage of the artery and vein belonging to the retina.J These vessels ramify, by a few branches, on the internal surface of the membrane, and form a sort of circle surrounding the yellow spot. Neither the branches of the artery nor of the vein communicate with those of the choroides; and, as observed, never go beyond what we just considered as the anterior margin of the retina, but rather run along it. Interposed between the retina and the choroides, is a most deli? cate serous membrane, which was discovered by Mr. Jacobs, Demonstrator of Anatomy in Trinity College, Dublin. By pre- paring the retina in the usual way, and then floating the eye in a * Comment. Soc. Reg. Sc. Gottingen, 1779. t In a careful examination of the eye of Williams the murderer, executed in the Moyamensing Prison, Aug. 9, 1839, I found (in three hours after the drop fell, the eye consequently being perfectly fresh,) the retina, in both eyes, of the colour of oiled white paper or ground glass : it was seen distinctly to terminate at the begin- ning of the ciliary plaits of the choroid. The spot of Soemmering was seen, but it was of a sea green, oval, a line in length, the centre marked by an olive spot: no forameowas seen; satisfactorily. The fold of the retina, running to the entrance of the oplie nerve, was very distinct, as well as the button-like appearance of the nerve at this point. X The point where the central arte*y ef the Retina enters, is called the Macula Lutea. Michaels-asserts, that around it the filaments of the retina are arranged in arches, of which one part meets in the macula lutea, the next in succession converge regularly towards a line stretching from the macula lutea. Muller ut Supra. THE BALL OF THE EYE. 445 saucer of water, this membrane may be turned down with the handle of a scalpel from the optic nerve to the termination of the retina. It is supposed to be the seat of the ossifications which are sometimes met with in the eye. Humours of the Eye-Ball. The Vitreous Humour (Humor Vitreus, Corpus Vitreum,) oc- cupies, with the exception of a very small part just behind the iris, the whole of the space posterior to the latter. It is, therefore, very nearly globular; is in contact the greater part of its extent with the retina, and at least as far as the latter membrane pro- ceeds ; in front it is in contact with the crystalline humour, and from the margin of the retina to the circumference of the lens it is in contact with the ciliary body, meaning thereby the ciliary striae and processes of the choroides. Two parts compose the vitreous humour,—the hyaloid mem- brane and a thin fluid. In a natural state they are perfectly trans- parent, and, therefore, cannot be readily distinguished from each other; but by immersion in spirits of wine the membranous por- tion is brought to the colour of ground glass, and may then be studied very advantageously. The membrane, though extremely delicate, is generally strong enough to permit the whole vitreous body to be suspended in the air by a thread passed through it, and. it may also be momentarily held up with a pair of forceps.* The Tunica Hyaloidea may be traced as a complete capsule, forming the periphery of the vitreous humour; and from the inter- nal face of this capsule there proceeds a great number of parti- tions dividing the whole cavity into cells of various magnitude and form. Some anatomists, who have frozen the eye, and then picked out the pieces of ice from the cells, have the notion of their being all cuneiform, and of their edges pointing forwards. Our preparations in the anatomical cabinet are perfectly satisfactory * In Williams the criminal, executed here, as stated before, I found on the front of one hyaloid, just at the side of the lens an opacity of three by six lines, resem- bling an opacity of the cornea, it was just where the tunica hyaloidea is in contact with the ciliary plaits of the choroid and was first mistaken for a metallic like sur- face of the latter, as the tapetum of the lower animals. 446 NERVOUS SYSTEM. in exhibiting the existence of an arrangement of cells, but do not manifest a regular cuneiform shape in them. When the capsule of the tunica hyaloidea has got to the dis- tance of two lines, or thereabouts, from the circumference of the lens, it divides into two laminae, which reunite at the circumfe- rence of the lens. They then divide again, and one goes before the capsule of the lens, and the other behind it. The space be- tween the two layers, around the circumference of the lens, is the Canal of Petit, and is that part of the tunica hyaloidea which is impressed by the ciliary striae and ridges of the choroides. At intervals, passing in a radiated manner from the exterior to the interior circumference of the canal, there is a sort of shortening or constriction of it, producing partial septa in its cavity; so that when the canal is inflated, it seems to consist of a series of small cells, arranged circularly. The cells of the colon will give some idea of this arrangement, though they are produced in an entirely different manner. The fluid part of the vitreous humour, by analysis, gives out 98.40 water, .16 albumen, and the remainder is saline. In conse- quence of the very small quantity of albumen in it, neither acids nor heat coagulate it to a striking degree. The vitreous humour is supplied with a branch from the cen- tral artery of the retina. This branch does not convey red blood but only serum, except in the fcetal eye. It may be injected, at almost any age, with size, coloured with vermilion; but is then, of course, put very much on the stretch. It has been well described by Zinn. It penetrates the vitreous humour near the optic nerve, and is disseminated by very fine branches on the periphery, and on the internal cellular slructure of the tunica hyaloidea. M. J. Cloquet has described particularly one branch, which, running through the centre of the vitreous humour, in an appropriate canal, is spent by small ramifications upon the posterior part of the cap- sule of the lens. Some anatomists* speak of a fluid between the tunica hyaloidea and the retina: when it does exist, it in all probability is the fluid of the vitreous humour, which has strained through the tunica hyaloidea after death. Bichat, Anal. Dcscrip. THE BALL OF THE EYE. 447 The Lens (Lens Crystallina) or the Crystalline Humour, as it is very generally called, is placed immediately behind the pupil, in a depression on the front of the vitreous humour. Its shape is that of a doubly convex lens, of which the posterior convexity is greatest, being the section of a sphere whose diameter is from four to five lines, while the anterior convexity is in the proportion of a sphere of from six to nine lines. The usual breadth of the lens is about three and a-half lines. It, however, varies its shape in a re- markable degree at the different periods of life; immediately after birth it is spheioidal, in about six years, afterwards its lenticular shape is well marked, and, subsequently, it becomes more flat and thin. The lens naturally is perfectly transparent. In the greater part of its thickness it has the consistence of half dissolved glue, but its centre is much more solid; this change, however, is effected suc- cessively from the circumference to the centre. When it is sub- jected to the mineral acids, to heat, to alcohol, and several other agents, it becomes much more solid throughout; it may then be separated, like an onion, into a series of concentric lamellae, subdivi- sible into longitudinal fibres. Besides these, there are fibres more or less oblique which hold the lamellae together. These arrange- ments prevail from the centre to the circumference of the lens; and between the laminae there is a diaphanous humour resembling that between it and its capsule.* The lens has a natural but adhering division into three equal parts perfectly alike in shape, like an apple which one may have divided in that way. The filaments of which the laminae are com- posed, run from before backwards, and have their ends directed towards the limits or lines marking out the primary division into three parts. Sir David Brewster has shown by the action of po- larized light, that those filaments are undulated or dentated at their edges, by which means they adhere. This is most distinct in fishes. The fibres of the lens are considered by Schwann to be originally formed from cells, which are elongated and joined together. Albumen enters very largely into the composition of the lens, which is readily proved by the thorough opacity following its immersion in spirits of wine. The lens is invested by a capsule which is a complete sac, • J. F. Meckel. 448 NERVOUS SYSTEM. having exactly its shape, but separated from it, to a very inconsi- derable extent, by the transparent humour just alluded to, called the Liquor Morgagni. The capsule is covered in front by a layer of the tunica hyaloidea adhering very closely to it, but which, in one instance, I was enabled to peel off partially in the eye of a sheep, from one side to the other. The capsule is covered in like manner, on its posterior face by the tunica hyaloidea; but the two may be separated there more easily, according to the observations of Bichat. Some of the most distinguished continental anatomists are decidedly in favour of the capsule of the crystalline being a complete bag; but it is rather unsettled whether the exterior mar- gin of the capsule bounds the lesser circumference of the Canal of Petit, or whether the two layers of the tunica hyaloidea unite pre- viously at the circumference of the capsule. The latter seems to be the opinion of M. J. Cloquet. The late Dr. Physick, in some cases of membranous cataract, has succeeded in drawing out the capsule entire, so as to exhibit its whole extent when floated in water. The capsule in front of the lens is much thicker than the tunica hyaloidea, and its difference of character from the latter appears to me to be very strongly marked ; for, notwithstanding its immer- sion in spirits of wine, it retains its transparency. It is hard and elastic, and when clipped with the scissors, gives nearly the same sensation as the thin paring of a finger nail would; or, as has been observed by Haller, it, in this respect, resembles the cornea. The analogy with the cornea ceases, however, at this point; for the cornea has always so much albuminous matter in it as to be rendered turbid when it is immersed in alcohol. The posterior half of the capsule of the lens, is not so well marked either by its thickness or specific characters as the anterior, yet our preparations in the Uni- versity demonstrate its existence equally as conclusively. It is more assimilated to the nature of the tunica hyaloidea. In the injected foetal eye, the artery of the tunica hyaloidea which comes from the central one of the retina, is seen to furnish several minute ramifications to the posterior face of the lenticular capsule; some of its branches also go to the front of the capsule, but the latter part is furnished principally by arterioles from the ciliary body of the choroides. The two sets of arteries anas- tomose with each other; some of the latter are also spent upon ihe membrana pupillaris. THE BALL OF THE EYE. 449 The point is yet doubtful whether any of these arteries penetrate into the body itself of the crystalline humour. Ruysch, Albinus, and Haller, assert the fact of their having seen and injected them in the human species and in animals, and J. F. Meckel admits their testimony. Yet there are not many anatomists who can corrobo- rate it by their personal observations. It is sufficiently reasonable to admit it; for without, we cannot conveniently account for the growth and nutrition of the lens, as well as the morbid changes which occur in it. It should be observed that if this vascular con- nexion do exist, it is a very weak one: for the lens seems to be simply surrounded by its capsule without adhering to it. Some veins which discharge into the veins of the choroid coat, have been observed by Walter* on the posterior part of the cap- sule. It should be continually borne in mind that neither the arte- ries nor veins of the healthy crystalline, nor of its capsule, convey red blood: in which respect they correspond with the hyaloidea; for, if this were the case, vision would be very much disordered by it. It may be that the moats or specks seen in ophthalmia arise from the grosser particles of the blood getting into these serous vessels, by the dilatation of the latter. The Lens and its Capsule are devoid of nerves, at least none have been as yet traced into them. The Aqueous Humour (Humor Aquosus) occupies the space which is between the anterior face of the crystalline capsule, and the posterior face of the cornea. This space is unequally divided by the iris into two chambers, of which the anterior is in front of the latter membrane, and the posterior behind it. In consequence of the convexity of the lens, the posterior chamber has but very little depth just behind the pupil; but its space is augmented at the circumfe- rence of the crystalline, so as to leave room for the floating of the ciliary processes and for the motions of the iris. The posterior chamber is, therefore, a circular vacuity; the centre of which, from the projection of the centre of the crystalline, has scarcely any appreciable depth. The anterior chamber, in its shape, resembles the segment of a sphere: its depth depends essentially on the size and the projection of the cornea. The aqueous humour is perfectly transparent, and almost as • De Oculis. Berlin, 1778. Vol. II.—39 450 NERVOUS SYSTEM. fluid as water. The analysis of Berzelius exhibits 98 parts of water, -^ of hydrochlorate and lactate of lime, TV °f some animal matter soluble in water, and a very small quantity of albumen. From the latter circumstance it will be understood how this fluid refuses to coagulate on the addition of alcohol or of mineral acids to it, and is only rendered in a very slight degree turbid by them. The rapidity of the exhalation of this fluid is remarkable; when the whole of it is lost in the operation for cataract, it is regenerated in from twenty-four to thirty-six hours. Its source has been sought for in suppositive canals and glands, but the more probable opinion is, that it may come from any or all of the exhalent arteries of the chambers of the eye. Like the other two humours of the Eye, the aqueous is furnished with a capsule, but whether it is complete or not is yet undeter- mined. By immersing the eye in hot water, or in alcohol, this capsule may be readily detected on the posterior face of the cor- nea, and to the greater circumference of the iris; it may even be traced for some distance on the front surface of the latter. Some of the French anatomists, as Demours,* Descemet, and J. Cloquet, have asserted that it continued also through the pupil to line the posterior chamber. An opinion like this, from the extreme tenuity of the part, must be rather the result of conjecture than of accu- rate observation: it has, therefore, never found its way with full force into the writings of anatomists. The loose condition of the pigmentum nigrum on the posterior face of the iris, and on the ciliary processes, would seem to be an objection to the existence of this capsule in the posterior chamber of the eye. But, if it really does exist there, as is pretended by M. Portal, who supposes it to be derived from the tunica hyaloidea, its structure is incomparably more delicate than that part on the cornea, and, indeed, is merely gelatinous. The Chambers of the Eye, till the seventh month of foetal ex- istence, and sometimes later, are perfectly separated from each other by the Membrana Pupillaris, called so from its position in the pupil of the iris. It was discovered in 1740 by Wachendorf, and is sometimes called after his name. It is a thin, delicate, and transpa- rent membrane, which is stretched across the pupil from its circu- * Demours, Lettre, 1767. THE EAR. 451 lar margin, and may, by its colour, be readily distinguished from the iris, when it has been made somewhat turbid by alcohol. The Membrana Pupillaris consists, according to M. J. Cloquet,* of two laminae placed back to back, of which the foremost is a continuation of the membrane which lines the anterior chamber of the eye, and the hindmost of that which lines the posterior cham- ber. According to this, it may be noted that each chamber has its distinct capsule. This membrane is very vascular; some of its arteries are those which subsequently form the internal arterial circle of the iris, and they radiate from the circumference to the centre of the membrane; others come directly from the long ciliary arteries and others again from the arteries of the crystalline cap- sule. These several vessels are found principally on its posterior face. Its veins have not been observed. This membrane first shows itself about the third month of foetal existence, and is most perfect at the seventh; from the latter period it begins to decline, by disappearing from the centre to the circumference. At the ninth month it consists only in a few loose flocculent masses adhering to the pupil. M. J. Cloquet has ascer- tained that its vessels do not participate in its destruction, but that the arches which they form are retracted to the margin of the pupil, and there form the lesser arterial circle of the iris. From the observations of Drs. Jacob and Tiedemann, it appears that traces of the membrana pupillaris exist for ten or fifteen days after birth. The latter, in one case, injected its vessels in a foetus at full term.f CHAPTER III. Of the Ear. The ear, the organ of hearing is placed principally within the petrous portion of the temporal bone, and consists in the External Ear, or Auricle, the Tympanum, and the Labyrinth. * Journal Universellc des Sc. Med. Paris, 1818. Mem. sur la Memb. Pupill. Paris, 1818. t Amcr. Med. Jour. vol. i. p. 192. 452 NERVOUS SYSTEM. SECT. I.—OF THE EXTERNAL EAR. The position of this portion of the organ is familiar to every one. It is useful in collecting the rays of sound, and in conveying them to the more internal parts. It is formed by the structure, exterior to the petrous bone, called, in common language, the Ear; and by a bony canal which leads internally to the tympanum. The basis of the first portion is cartilaginous, on which circum- stance it depends for the permanency of its shape. The ear, of common language, is divided into two parts, Pinnaf and Lobus: the former is the most extensive, as it comprehends all the cartilaginous portion: the latter is attached to the inferior margin of the former, and, having no cartilage in its composition, is soft and pendulous. In the centre of the external ear is a deep depression called the Concha; in the bottom of it is the orifice of the canal leading to the tympanum, and called Meatus Auditorius Externus. The cir- cumference of the pinna is convoluted into a scroll called the Helix, and commences just above the meatus by a ridge. This ridge divides the concha into two unequal cavities, of which the lower is the larger. The scroll becomes gradually less prominent, till it terminates at the posterior inferior part of the pinna," in the lobus. The Antihelix is the slightly curved and vertical eminence in the middle of the pinna: its lower part forms the posterior boun- dary of the concha, and its upper part bifurcates into two small ridges, between which there is a depression called the Scapha. Between the antihelix and the posterior half of the helix, is an oblong depression called the Fossa Innominata. The Tragus is a cartilaginous elevation of the pinna placed in front of the concha, and inclining somewhat over it; opposite to it, at the inferior part of the concha, is the Antitragus. The cartilaginous plate, upon which the external ear depends for its shape, is of a thickness very nearly uniform; of course, the ridges and depressions on its exterior surface have corresponding depressions and ridges on the side next to the head. It is inter- * From some resemblance to a certain shell fish. THE EXTERNAL EAR. 453 rupted at several places by fissures ; for example, there is one of considerable size filled up with ligamentous matter, which sepa- rates the upper margin of the tragus from the beginning of the helix: there is another between the lower extremity of the anti- helix and the antitragus. In the tragus, there are two, and some- times three, small narrow ones, said, by Santorini, to be filled with muscular fibres; but the latter assertion does not correspond with the observations of subsequent anatomists, as the matter appears fibrous. The external ear is united to the side of the head by three liga- ments. The anterior arises from the root of the zygomatic pro- cess above the articulation of the lower jaw, and is inserted into the pointed production of cartilage on the fore part of the helix. The posterior arises from the swell of the temporal bone, which runs into the front margin of the base of the mastoid process, and is inserted into the convex side of the concha, at the beginning of the meatus auditorius. The superior arises from the temporal aponeurosis, and is inserted into the upper part of the concha. These ligaments lie immediately below the muscles destined to move the ear. The Meatus Auditorius Externus, is, in the adult, an inch in length, reckoning from its external orifice to the membrane of the tympanum, which closes it inwardly. It is about three lines in diameter, is rather oval than cylindrical, and somewhat smaller in the middle than at either of its extremities. It runs inwards, with a slight inclination forwards; the exterior half is formed by the cartilage of the pinna, and the internal half by the temporal bone : it departs from the horizontal course, in being curved at its middle where the two sections join. This curvature has ils convexity upwards, so that when we wish to look to the bottom of the canal, the external ear must be pulled upwards and backwards. The cartilaginous portion of the meatus auditorius is formed by a triangular piece springing from the base of the tragus and from the inferior anterior part of the concha. This portion is nearly a tube, but is interrupted above and behind by the intervention of a dense fibrous tissue, continuous with, and indeed the same with that which joins the helix and the tragus. The internal margin of the cartilaginous meatus forms a point below; and adheres closely bv ligament to the asperities on the margin of the bony 39* 454 NERVOUS SYSTEM. meatus. If there were no fissures in the external ear, it would, therefore, be almost immoveable. The skin covering the external ear is more delicate than in most other parts of the surface of the body. Its sebaceous glands or follicles are very abundant, and in infants secrete freely their peculiar fluid. When a slight inflammation occurs, this discharge is frequently purulent without erosion. A duplication of the skin, containing a delicate granulated adeps with some fibrous matter, constitutes the lobe of the ear. The skin, after lining the concha, descends into the meatus auditorius, and lines it also as well as the external face of the membrane of the tympanum. It adheres moderately to the car- tilaginous part of the tube, and more tenaciously to its fibrous portions: between it and the latter are found many small reddish bodies, generally oval, the Glandulae Ceruminosae,* from which proceeds the earwax.f The skin is extremely thin in the bony meatus, adheres closely to its periosteum, and is highly sensible: where it forms the exterior layer of the membrane of the tympa- num, it may be detached from the latter with the slightest force, and seems to be converted almost entirely into cuticle. A slight maceration or incipient putrefaction frequently enables one to draw the cuticle out entire from the meatus, so that it looks in shape like the finger of a small glove. The dermoid lining of the meatus, at its external orifice, is studded with fine hairs, which serve to keep out small bodies that may be floating in the air. A considerable number of small pores are also seen in if, which are the orifices of the ducts of the ceru- minous glands. The discharge of the latter, when first secreted, is thin and white: by evaporation, it becomes thick and yellow, and by accumulating obstructs the passage. There are several small muscles situated on the external ear, which are for the most part so feebly developed that they cannot always be found, and when they do exist they seem more like the * Duverney, OZuvres Anatomiques. t They are placed, according to Buchanan, for the major part, in the middle and superior face of the meatus, and their number he estimates at from one to two thousand. Physiolog. illustrations. 1825. THE TYMPANUM. 455 rudiments of what is well marked in animals, than intended for a special purpose in the human body. 1. The Helicis Major is an oblong fasciculus, situated on the front of the helix. By its lower end it is attached to the point of cartilage on the front of the helix, and its other extremity extends to the top of the latter. 2. The Helicis Minor is a small square fasciculus, also on the front of the helix, between the folded margin of the latter and the inferior half of the helicis major. 3. The Tragious is a square fasciculus, on the front surface of the tragus, near its margin: its upper extremity sometimes runs into the helicis major.. 4. The Antitragicus is a small oblong fasciculus, which arises from the upper extremity of the antitragus, and going upwards it is inserted into the inferior extremity of the antihelix. 5. The Transversus Auriculae is on the internal surface of the pinna. It arises from the prominence of the concha, and is inserted- into the hollow dorsum of the antihelix.. 6. The Dilatator Conchae, or Musculus.. Incisurae Majoris of Santorini is small, and extends from the front of the helix across the great fissure, outwards and downwards to the tragus. It dilates the concha. There are some other muscles which may be uniformly found, and are intended to move the external ear upon the side of the head, though from the want of exercise there are very few in- dividuals capable of making them contract. They are as fol- lows: 1. The Attollens Auriculae is placed on the side of the head be- neath the integuments: it is a broad, thin, and somewhat triangu- lar muscle, which arises from the inferior margin of the tendon of the occipito-frontalis, and from the temporal aponeurosis. It be- comes narrower in its descent, and is inserted tendinous into the 456 NERVOUS SYSTEM. upper end of the pinna by the elevation corresponding with the scapha. Its name implies its action to be that of raising the pinna. 2. The Retrahens Auriculae, consists in two or three oblong fasciculi, placed parallel, and one above the other. It arises from the mastoid portion of the temporal bone, above the mastoid pro- cess, and is inserted tendinous into the convex side of the concha near the meatus auditorius. It draws the pinna backwards. 3. The Anterior Auriculae is a small quadrangular slip, just above the root of the zygomatic process. It arises from the tem- poral fascia, and is inserted tendinous into the fore part of the helix just above its beginning. It draws the pinna forwards and upwards. SECT. II.---OF THE TYMPANUM. The Tympanum is the middle portion of the organ of hearing, being interposed between the meatus auditorius and the labyrinth. Its depth is about three lines, its antero-posterior diameter about six, and its vertical diameter rather more, though from the general inequality of the cavity, and its communication with adjoining cavities, it is not easy to fix upon very precise measurements. The Membrana Tympani, is a complete membranous septum, interposed between the meatus externus and the tympanum. It is placed very obliquely, so that its upper edge inclines outwards, and its under edge inwards; the latter, therefore, forms a very acute entering angle with the inferior part or floor of the meatus, and gives to that portion of the meatus an additional length, which renders it difficult to see to its bottom. The membrane of the tympanum is nearly circular, and has its circumference adhering very closely to the external orifice of the tympanum. It is slightly tense, and has its middle drawn inwards by being attached to the handle of the malleus. The membrani tympani consists of four laminae; the two exte- rior of which, being the cuticle and the cutis vera, which line the meatus auditorius, are easily detached, as mentioned before, and T.HE TYMPANUM. 457 seem scarcely to adhere to the layer below. The third layer is the proper membrane, and is distinguished by its dryness and by its transparency. Sir Everard Home was enabled to detect radi- ated muscular fibres, forming it in the elephant.* In the human subject, its fibrous character is best seen on its internal face, but the radiated arrangement is not so distinct. Caldani considers it as formed by filaments, decussating each other at right angles, and intermixed with blood vessels.f The internal layer is a con- tinuation of the lining membrane of the tympanum; it is separated with some difficulty, owing to its tenuity. The proper membrane of the tympanum, when successfully in- jected, exhibits a high degree of vascularity ;J though, in its natural state, but very few red blood vessels are seen in it. The floor of the tympanum, or the side next to the labyrinth, presents an unequal surface. In its middle is a well marked rising, the Promontory, (Promontorium,) formed by one end of the labyrinth. Just above the superior margin of this prominence, near its centre, is an oval opening, called, from its shape, Fora- men Ovale, or Fenestra Ovalis; having its long diameter hori- zontal, its superior margin rounded or concave, and its inferior straight. At the posterior inferior part of the promontory is ano- ther opening, which, though somewhat triangular, is called the Foramen Rotundum, or Fenestra Rotunda, and in the dried bone leads to the cochlea, but is naturally stopped by the lining mem- brane of the tympanum. According to M. Ribes, this membranous plug has also two other layers, an internal one, the continuation of what lines the cochlea, and a middle one, which is peculiar. In these respects, there is a correspondence with the membrana tympani. The Eminentia Pyramidalis is a small conical eminence pro- jecting from the posterior part of the tympanum, on a line with the fenestra ovalis. It is hollow, contains a muscle, and commu- nicates at the other end with the Canal of Fallopius. Lower down, * Philosophical Transactions, for 1800. London. t Plate XCVIII. Anat. X Ruyschii, Epist. Anat. Probl. viii. Also Anatomical Museum, Univ. Penns. 458 NERVOUS SYSTEM. and more externally, there is a small orifice, (Apertura Chordae,) through which the nerve called Chorda Tympani passes. The Mastoid Portion of the Temporal bone, in the adult, abounds in large cells or sinuses, which communicate freely with one ano- ther. They are distinct from the*diploic structure of the bone, as they contain no medulla, and are lined by a continuation of the internal membrane of the tympanum, which is extremely thin upon them. The orifice of communication between these cells and the tympanum, is placed at the superior posterior part of the latter: it is rough and irregular, and partially occupied by the short leg of the incus. Just in front of this opening, the cavity of the tympa- num is extended vertically, for the purpose of accommodating the body of the malleus and of the incus, whereby they are in a great degree concealed, unless the corresponding margin of the tympa- num be cut away. At the fore part of the tympanum is the Eustachian Tube, which runs for six or eight lines in the substance of the petrous bone, near its exterior margin; and then terminates in a cartila- ginous and membranous portion, which communicates with the pharynx at the posterior naris. The latter extremity of the Eusta- chian Tube is placed on a line with the posterior end of the infe- rior spongy bone. Its orifice is rounded or oval, is large enough to admit the tip of the little finger, and reposes against the side of the internal pterygoid process of the sphenoid bone. Though almost within the precincts of the posterior naris, this orifice is to be considered as opening into the pharynx. This canal, in its whole length, measures nearly two inches, and, with the exception of the portion in the petrous bone, is carti- laginous and membranous. The cartilage is a single, thick triangu- lar plate, flat, and adhering by one of its edges to the internal ptery- goid process. The under part of the tube is membranous, thin and affords attachment to some of the muscles of the soft palate. Its course is nearly horizontal, backward and outward. It is lined in its whole extent, by a very fine mucous membrane con- tinuous with that of the pharynx and of the tympanum. This mem- brane is thickened at its anterior extremity by the mucous glands beneath it, which assist in giving the marked elevation to its ori- THE TYMPANUM. 459 fice. The canal diminishes as it goes backward, so as to receive with difficulty a small probe. Parallel with the bony part of this canal, but above it, and separated by a very thin partition of bone, is another canal which lodges a muscle of the malleus. On the outer side of the Eusta- chian tube is the glenoid foramen, by which, in the dried bone, the tympanum communicates with the glenoid cavity; in the recent state the foramen receives the long process of the malleus and its muscle, and transmits the chorda tympani. There are four bones in the tympanum, which, being succes- sively articulated with each other, form a chain, one end of which is fastened to the membrana tympani, and the other end rests upon the foramen ovale. They are the Malleus; the Incus; the Orbicu- lare; and the Stapes. The Malleus forms the fore part of the chain, and is placed almost vertically. Its superior extremity is the head, which is rounded, with the exception of the posterior face, where a small concavo-convex surface is observable, for its articulation with the incus. Its lower extremity is long and tapering, inclines inwardly, terminates by a little knob, and forms an angle with the part above; this portion is the manubrium, and adheres its whole length to the membrana tympani, commencing at the superior margin of the latter, and insinuating itself between the internal and the proper layer, as far as the centre of the membrane. It is this adhesion with the inclination inwards of the manubrium, that causes the membrane to be depressed in its centre. Between the head and the manubrium is a short portion called the neck. From the superior external extremity of the manubrium there proceeds outwardly the short process, (Processus Brevis;) and from the front of the neck, there proceeds the long and very delicate process, concave externally and convex internally, which is insinuated into the glenoid foramen, and is the Processus Longus, or Gracilis. The Incus is behind the malleus, and is also upright. It consists in a body and two branches, which diverge very considerably, and has a general resemblance to a molar tooth. The body pre- 460 NERVOUS SYSTEM. sents, on its forepart, a deep concavity, which articulates with the convex head of the malleus. The branch which arises from the back part of the body is horizontal, looks into the orifice of the mastoid cells, and is much shorter than the other. The inferior branch is long, upright, tapering, and nearly parallel with the ma- nubrium of the malleus, but somewhat within it. The Orbiculare is a very small flattened sphere of bone, which articulates with the lower end of the long process of the incus, and in adult life is most generally fused into it, so as to lose its distinc- tive character: the latter change sometimes occurs even in early infancy. The Stapes is the last of the chain. It resembles very strongly the common stirrup iron, from whence its name, and is placed horizontally at right angles to the incus, being separated from the extremity of the long process of the latter by the os orbiculare, and being directed inwards to the foramen ovale. It is composed of a head, two crura, and a base. The head is oblong and flattened : it has a slight depression where it joins the orbiculare. The crura are slightly curved, with the concavities towards each other: the anterior is somewhat straighter than the posterior, and is also shorter. They are both excavated, longitudinally, on their concave surfaces, and between them is stretched a process of the lining membrane of the tympa- num. The base is precisely adapted to the fenestra ovalis, and is connected to it by the lining membrane of the tympanum, but not so closely as to prevent it from executing slight vibratory move- ments. Between the malleus and the incus there is a moveable articula- tion with a synovial membrane, but the other joints of the chain are simply ligamentous. This chain of bones is moved by several muscles, which influ- ence the degree of tension of the membrana tympani. 1. The Laxator Tympani arises from the posterior end of the spinous process of the sphenoid bone, and passing behind the arti- culation of the lower jaw into the glenoid foramen, is inserted, ten- dinous, along the processus gracilis of the malleus. THE TYMPANUM. 461 It draws the malleus forwards and outwards, so as to relax the membrana tympani. 2. The Tensor Tympani is placed in the canal just above the Eustachian tube. It arises from the posterior extremity of the cartilaginous portion of the latter, and having got into the tympa- num, is changed into a small tendon, which, going outwardly, is inserted into the neck of the malleus, just below its processus gra- cilis. It draws the malleus inwardly; consequently makes tense the membrana tympani, and drives the stapes into the fenestra ovalis. 3. The Stapedius arises from the bottom of the cavity in the pyramid, and terminates in a small round tendon, which, going through the apex of the latter, is inserted into the head of the stapes. It draws the stapes backwards, and perhaps fixes it more firmly by its contractions. 4. There is a fourth muscle mentioned by anatomists, the ex- istence of which is more equivocal; it is called the Laxator Tym- pani Minor. It is said to arise from the superior margin of the orifice of the tympanum, and to be inserted into the processus brevis of the malleus. It is by some considered only as a liga ment, to which opinion I am inclined. Of the Lining Membrane of the Tympanum. This membrane is a continuation of the lining membrane of the pharynx, being introduced into the tympanum through the Eus- tachian tube. It covers completely the surface of the tympanum, and is reflected over its little bones so as to give them a covering also; in addition to which, it lines such of the mastoid cells as communicate with the tympanum. This membrane is extremely delicate: on its surface, adjacent to the bones, it is somewhat fibrous, and thereby resembles perios- teum; but the other surface has the characters of the mucous membranes generally, in the nature of its secretion, and in its vas- cularity, which is very strongly marked in inflammations, and by fine injections. Bichat mentions, that in certain catarrhal affec- Vol. II.—40 462 NERVOUS SYSTEM. tions its mucous secretion is so abundant as to fill the whole cavity of the tympanum, and that without ulceration. Sometimes, in such cases, the membrane of the tympanum is ruptured, and the discharge finds its way out through the meatus externus, present- ing itself in a purulent state, as if an abscess had formed in the ear. SECT. III.---OF THE LABYRINTH.* The Labyrinth (Labyrinthus) is placed on the inner side of the tympanum, in the thickness of the petrous bone. Its exterior pa- rietes are bone, but internally there is a membranous structure, having, in many respects, the same shape. It is got at with great difficulty in the adult, owing to the compactness of the petrous bone which envelops it; but in the foetus of the full period, where it is almost as large as in the adult, the surrounding bone is of a softer and more spongy texture, and may be pared away with a pen-knife without much trouble. In the latter case, the parietes of the bony labyrinth remain about the thickness of an egg-shell, and have very much the same degree of consistency and strength. The bony labyrinth consists of three portions: the Vestibulum, the Semicircular Canals, and the Cochlea. The Vestibulum is the cavity to which the foramen ovale leads ; it, with the cochlea, occasions the protuberance into the tympa- num, known as the promontory. It is an irregular rounded exca- vation, the surface of which is impressed by its contents; thus, at the superior posterior and external part, next to the semicircular canals, there is a superficial Fossa, called, from its shape, Semi- Elliptica, and at its anterior and inferior part, nearer the cochlea, another, called Fossa Hemi-Spherica. These fossae are marked off from each other by a ridge of bone, at the lower end of which there is a third fossa between the other two, called by Soemmer- ing, Cavitas Sulciformis. There are seven orifices belonging to the vestibulum besides the foramen ovale; five at its posterior part leading into the semicir- cular canals; one anteriorly leading into the upper scala of the cochlea: and the last placed in its internal paries is the aqueduct * Antonio Scarpa, Disquisit. de Auditu et Olfacto. THE LABYRYNTH. 463 of the vestibule. In addition to these orifices, the parietes of this cavity are cribriform in the fossa semi-elliptica and near the fora- men rotundum.* The Semicircular Canals (Canales Semicirculares) are at the posterior extremity of the vestibulum. They are three in number, and are named from their relative situation, Superior or Anterior, Posterior or Inferior, and External. Each one forms rather more than the half of a semicircle, and has its cavity about half a line in diameter: their orifices are somewhat dilated beyond this mea- surement. The apparent thickness of their parietes is greater in the adult than in the infant. The Superior Canal runs from without inwards and backwards. Its anterior orifice is above the fenestra ovalis, and is enlarged into an ampulla or elliptical cavity. At its posterior extremity, it joins the upper extremity of the inferior canal, so that a common trunk is thus formed, the orifice of which is at the internal poste- rior part of the vestibulum, and is dilated into the shape of a funnel.I The Posterior or Inferior Canal is nearly vertical; has its concavity in front, and its convexity behind, and joins, as just remarked, with the superior; its inferior orifice, which is near the foramen rotundum, is also enlarged into an ampulla or elliptical cavity. It is the longest of the three canals, and has its ends nearer together. The External Canal is nearly horizontal, and is placed in the space left by the divergence of the other two. It is the shortest and the largest of the three. Its exterior orifice is also enlarged into an ampulla or elliptical cavity, and is just behind the foramen ovale, or below the ampulla of the upper canal; the internal orifice is below the common opening of the other two canals. It is the union of the superior and of the posterior canals at one of their extremities, which reduces the number of openings into the vestibulum, from the semicircular canals, to five instead of six. The Cochlea forms the fore part of the labyrinth, and resembles very strongly the shell of the common snail. Its base is the bottom * Ant. Scarpa, loc. cit. t Scarpa, loc. cit. 464 NERVOUS SYSTEM. of the meatus auditorius internus, and its apex is directed towards the cavity of the tympanum, so that the axis of the cochlea is turned downwards and outwards. It consists in a conoidal tube wound spirally twice and a half around a column of bone termed the Modiolus.* The tube then of course diminishes in size from the base to the apex of the cochlea. This conical tube is divided in its length by a plate called La- mina Spiralis. Of the two compartments thus formed, and called Scalae or stairs, one is above the other. The inferior is the larger, and communicates at its base, through the foramen rotundum, with the tympanum ; it is, therefore, called Scala Tympani. The other compartment communicates at its base with the vestibulum, and is, therefore, called Scala Vestibuli. The Modiolus is of a conical shape, and cribriform : one canal, larger than the others, runs from its base to its summit. This canal is surrounded by many others, which diminish successively as they advance towards the apex, and terminate in orifices upon the lamina spiralis. This cribriform arrangement of the modiolus is the Tractus Spiralis Foraminulosus. The base of the modiolus is towards the meatus auditorius internus, and its point does not go to the apex of the cochlea, but stops short of it, and is expanded into a cavity called the Infundibulum, the base of which is towards the apex of the cochlea. That portion of the apex of the cochlea which covers over the infundibulum, is the Cupola. It was just mentioned that the lamina spiralis divides the cochlea into two tubes; the septum thus formed, does not, however, run their whole length, for it ceases in the infundibulum by a small crooked process of bone, called the Hamulus Cochleae. The lamina, when examined by strong glasses, is seen to consist of four distinct structures called its Zones. 1. The Zona Ossea is next to the modiolus, and is composed of two bony laminae, with an intermediate diploic structure, in which are the canals for transmitting the filaments of the portio mollis or auditory nerve. 2. The Zona Coriacea, on the outer side of this, the structure of which is cartilaginous. 3. The Zona Vesicularis, said to contain in its cells a pellucid fluid. 4. The Zona Membranacea, which ♦ From its being like the nave or stock of a wheel in which the spokes are fastened. THE LABYRINTH. 465 is probably only the lining membrane of the cochlea, and com- pletes the lamina spiralis on its edge next to the periphery of the cochlea. Some very respectable anatomists pass over this minute distinction in the structure of the septum, and.merely divide it into Zona Ossea, and into Zona Mollis. Of the Membranous Labyrinth. The whole internal face of the bony Labyrinth is lined by a very delicate and vascular membrane, which is more distinct during the early periods of intra-uterine life. Besides this, there is a membranous labyrinth, consisting in three semicircular canals, nearly filling up the cavities, and having the same shape and gene- ral arrangement of the bony canals; and in two sacs contained in the vestibule. The Semicircular Membranous Canals have also at their ends the elliptical enlargements called ampullae; they terminate by both extremities in the sac of the superior part of the vestibule. This sac is generally called, from its shape, Sacculus Ellipticus; and by Scarpa, from its function, the Alveus Communis. In front of the Sacculus Ellipticus, nearer the cochlea, and opposite the fora- men ovale, is the Sacculus Sphericus ; it is a complete bag, having no communication with the other, or with the membranous canals. Both of the sacs adhere to the vestibulum at their posterior pa- rietes. The sacs of the vestibule and the membranous semicircular canals are filled with a very fluid transparent liquid. According to the observations of M. Ribes, it is not necessary to the function of hearing that this fluid should be so abundant as to distend the membranous labyrinth, inasmuch as in his dissections he met with individuals in whom the latter was only half filled, and yet they had heard very well. He also met with similar cases in which the fluid was abundant iu the vestibulum, but deficient in the canals, and the reverse. Corresponding observations have been made by M. Brugnone, of Turin,* where he had adopted the pre- caution of previously freezing the bone, so that none of the fluid could be said to have been lost by accident. From the frequency » Mem. de Turin, 1805—1808. 40* 466 NERVOUS SYSTEM. with which this deficiency was observed, his opinion seems to be well founded, that it is the most natural state of the labyrinth. The parietes of the membranous labyrinth are very thin and transparent; there is a very loose cellular tissue between them and the bone, and they are susceptible of being highly coloured by injection. A fluid of the same character with the preceding also fills the scalae of the cochlea, and extends itself into the bony vestibulum and the bony semicircular canals upon the outer surface of the membranous labyrinth. In the Sacculus Ellipticus are found some small crystalline pul- verulent masses of a calcarious composition. They are thought to contribute to the auditive function of the Labyrinth, and are called otoconie by Mr. Breschet* from their powdered state and position in the ear, in contradistinction to the term otolite or ear stone as seen in fishes and amphibia. Of the Aqueducts of the Ear. The Aqueducts (Aquxductus) of Cotunnius, as they are called after their discoverer, are two small canals which go through the petrous bone from the labyrinth. There is one for the vestibule, and another for the cochlea. The Aqueduct of the Vestibulum commences in the latter cavity, somewhat in advance of the common orifice of the two semicir- cular canals; it goes inwards and opens on the posterior face of the petrous bone, behind the meatus internus. It enlarges gra- dually in its course, which causes it to have somewhat of a trian- gular shape, and it is lined by a continuation of the dura mater. It is about four lines long. The Aqueduct of the Cochlea commences in the Scala Tympani, near the foramen rotundum, and, enlarging in its course, termi- nates on the under surface of the petrous bone, in the internal margin of the jugular fossa, at the root of the little spine which separates the eighth pair of nerves from the jugular vein. The anatomistsf from whom these canals were named, and who first described them, was under an impression that the fluid of the * Mem. de l'Acad. Royale de Med. Tom. 5. t Dominici Cotunnii. Anat. Dissert, de Aquaeduct. Naples, 1761. THE AQUEDUCTS. 467 labyrinth always filled it completely; and that without a sort of waste gate for it on an occasion, the vibration of the stapes would be prevented from putting the fluid in motion, and consequently, hearing must cease. These canals, the existence of which is suffi- ciently obvious in many subjects, were, therefore, considered by him as the desired avenues for the discharge of the superabundant fluid, and his theory and descriptions were very generally adopted. Of late years, the investigation of this subject has been renewed by MM. Ribes and Brugnone, and their observations are con- sidered by the French anatomists to have proved conclusively the error into which Cotunnius and others have fallen. In regard to the aqueduct of the vestibule, M. Ribes has found it only in three instances emptying into the vestibule; for most commonly it leads, after a course somewhat tortuous, into the spongy structure of the petrous bone, at the posterior part of the vestibule, and smaller canals diverge from it in different direc- tions. In the cases where it was connected with the labyrinth, it was so by several orifices leading into the vestibule, and into the posterior semicircular canal. He has not found this canal in the foetus, nor till some time after birth, and from his injections he be- lieves that, in all cases, it and its branches are only intended to convey blood vessels throughout the petrous bone and to the laby- rinth. In regard to the supposed aqueduct of the cochlea, M. Ribes has also found it diverging into collateral branches, and occupied by blood vessels, which are distributed to the spongy structure of the petrous bone, and to the tympanum. In my own researches on this point, on the dried bones, the canals, as described by Cotunnius, were closed at the labyrinth, in the case of subjects advanced in life; but, in the middle aged, and in infantile specimens, I have been more successful in tracing them fairly into the labyrinth, and have the preparations in the Wistar Museum. At the same time, I think it much.more probable that they only contained blood vessels, and that Cotunnius was in error. Besides these vascular canals, M. Ribes has described some others having the same use. 468 NERVOUS SYSTEM. SECT. IV.—OF THE NERVES OF THE ORGAN OF HEARING. The Nerves which pass through the petrous bone, and are either wholly or partially spent upon the organ of hearing, come from three sources. 1. The Auditory Nerve; 2. The Portio Dura; 3. The Trigeminus, or Fifth Pair. The Meatus Auditorius Internus conducts the first two, and has its bottom divided by a ridge into two fossae, of which the upper one is the smaller. This bottom, it has been observed, corre- sponds with the base of the modiolus, and is cribriform. One foramen, larger than any of the others,.and in the superior fossa, transmits the portio dura or facial nerve: all the others are occu- pied by the filaments of the auditory nerve. 1. The Auditory Nerve divides at the bottom of the meatus into fasciculi of filaments; one of which penetrates into the vesti- bulum through the foramina behind that for the portio dura, and is distributed upon the sacculus ellipticus, and upon the ampulla of the superior and of the exterior membranous canal; other fila- ments get to the sacculus sphericus; and a third fasciculus of fila- ments is distributed to the ampulla of the posterior membranous canal. These several filaments are said to preserve, when they first penetrate into the bony labyrinth, a fibrous appearance, and are interlaced; they also penetrate the parietes of the membranous labyrinth, and have their extremities bathed in its fluid, in which place they are converted into soft pulp, resembling mucus, or the retina. Another very considerable fasciculus of filaments penetrates into the canals of the modiolus, and enters through them into the cavity of the cochlea, along the Zona Ossea, and between its tables; they terminate also by a soft pulp on the internal face of the lining membrane of the cochlea. One of these filaments, conspicuous for its size, goes through the central canal of the modiolus and ter- minates in the infundibulum.* * For a knowledge of the minute distribution of the auditory nerve, the profes- sion is signally indebted to the distinguished Scarpa, inhJs D^squisitiones de Auditu et Olfactu. NERVES OP THE ORGAN OP HEARING. 469 2. The Facial Nerve, or Portio Dura, is only connected to the organ of hearing by sending a few filaments to the muscles of the bones of the tympanum. The canal of the petrous bone, through which it passes, is very crooked; beginning at the larger orifice of the meatus internus in its upper fossa, it passes outwards until it nearly reaches the Vidian foramen, on the front of the petrous bone; it then turns very abruptly backwards, forming an angle, and is continued in a circuit around the superior and the posterior parietes of the tympanum, till it terminates in the stylo-mastoid foramen. Its course is marked by a ridge projecting into the tympanum, above the foramen ovale, and passing between the semicircular canals and the cochlea. This canal has been very much misnamed by the calling of it the aqueduct of Fallopius, as its only use is to conduct nerves and blood vessels. It is lined by a delicate fibrous membrane, between which, and its contained parts, there is so little adhesion, that the latter may be drawn out entire. The facial nerve is joined at the Vidian foramen by the Vidian nerve, shortly after which it sends a filament to the tensor tym- pani muscle.* As it passes the base of the pyramid it detaches another filament, which supplies the stapedius muscle. Shortly after this, it is abandoned by the Vidian nerve, and does not give off any more branches till it escapes from the stylo-mas- toid foramen, when it sends off a branch, the posterior auricular (Auricularis Posterior,) which is distributed by filaments, some of which run into the mastoid process; other branches mount on the side of this process, to the skin which covers it, and to the occi- pital muscle: others go to the concha of the ear, being spent upon its skin, upon the posterior auricular muscle, and some of them, penetrating the pinna, are lost upon the integuments of the meatus externus. The trunk of the facial then goes to its destination on the face. 3. The Chorda Tympani or Superficial Petrous Nerve, is a branch of the Pterygoid branch of the Trigeminus, and leaves it near the anterior part of the carotid canal of the petrous bone. It, as just mentioned, under the name of Vidian nerve, joins the * The tensor tympani is also supplied by a nerve from the Third Branch of the Trigeminus. 470 NERVOUS SYSTEM. facial nerve at the angle of the canal of Fallopius, and continues to adhere closely to it, almost to the styloid foramen; it then abandons the facial nerve at a very acute angle, and running up- wards and forwards, gets into the cavity of the tympanum, on a level with, but a line or two exterior to the pyramid. It then crosses the tympanum nearly horizontally, between the long crus of the incus and the handle of the malleus, adhering to the latter so as to be affected by its vibrations. At the fore part of the tympanum, it anastomoses with some other filaments of the fifth pair, by which its size is augmented, but it gives no branches to the parts contained in the tympanum. It then issues from the latter cavity through the glenoid foramen, and descending a short but somewhat variable distance along the ramus of the lower jaw, terminates by anastomosing at an acute angle with the lingual branch of the trigeminus. To Mr. John Hunter is due the merit of having traced the con- tinuity and identity of the Vidian nerve with the chorda tympani. The continental European anatomists, for the most part, seem ignorant of his observations, and give a very different account of the matter. Some consider it to arise from the facial at its angle, and to anastomose at the other end with the pterygoid, or the re- verse; and they very generally agree in regarding the chorda tympani as a filament from the facial, just before the latter gets out of the stylo-mastoid foramen. The Vidian Nerve, or Superficial Petrous, also traverses the tympanum in another place. Just below the posterior extremity of the Eustachian Canal, there is a small foramen, which leads upwards to the superior surface of the petrous bone, and down- wards to a small gutter upon the promontory : this gutter is con- verted into a canal that opens upon the under surface of the petrous bone, between the carotid canal and the jugular fossa. Through the course indicated, passes a filament from the superficial petrous nerve: this filament is joined by another detached from the sym- pathetic while in the carotid canal, and the two communicate at the base of the cranium with the ganglion of the glosso-pharyngeal nerve.* These filaments were discovered by Professor Jacobson, of Copenhagen, and form what is now called the Anastomosis of Jacobson. * Meckel, Man. D'Anat., vol. iii., p. 174. Jacobson, Supplem. Act. Hafn , vol. v., p. 292. An. 1818. BOOK IX- PART IV. SPECIAL ANATOMY OF THE NERVES. CHAPTER I. Of the Nerves of the Encephalon. SECTION I. The course and distribution of the first pair, or the olfactory nerves, have been described fully in the account of the brain and nose. SECT. II.---NERVUS OPTICUS. The Optic nerve, as mentioned in the account of the basis of the brain, gets into the orbit by the optic foramen, and is there entirely surrounded by the origins of the muscles of the eye-ball. It then describes a slight curvature, of which the convexity is out- wards, and runs forwards for an inch, when it penetrates into the ball of the eye, where it gives origin to or expands into the retina. Between the muscles and it, except at their origins, there is a mass of adipose matter. 472 NERVOUS SYSTEM. SECT. III.—NERVUS MOTOR OCULI. The Nervus Motor Oculi, or third pair, having reached from the basis of the brain to the external side of the cavernous sinus, is placed there within and above the optic nerve and the sixth pair; it then changes its direction, and penetrates through the sphenoidal foramen or fissure into the orbit, on the outer side of these nerves, and below them. The motor oculi divides, in the sphenoidal fissure, into two branches, one above the other. The first crosses over the optic nerve and the nasal branch of the ophthalmic, having some anas- tomoses with the latter, and then distributes its filaments upon the rectus superior muscle; some of them also penetrate the latter to get to the levator palpebrae. The second branch is much larger than the first. It passes between the optic nerve and the rectus inferior muscle, and is subdivided into three fasciculi: one for the rectus internus muscle; another for the rectus inferior; and a third, which is the longest and the smallest, for the obliquus infe- rior muscle. The latter fasciculus, not far from its root, gives off a filament, which, going along the external margin of the optic nerve, runs into the posterior margin of the lenticular or ophthal- mic ganglion, and is its short root. The Lenticular Ganglion is situated on the outer side of the optic nerve, in the orbit of the eye, and is about a line in diame- ter, being flattened. Two nerves concur to form it: the branch just alluded to, from the motor oculi, and one from the ophthal- mic branch of the trigeminus. From this ganglion arise the most of the ciliary nerves; which, as stated, are about twenty in num- ber, and go to the choroid coat of the eye and to the iris. SECT. IV.—NERVUS TROCHLEARIS. The Nervus Trochlearis, or fourth pair, having got into its canal in the cavernous sinus, as it goes along the internal margin of the ophthalmic nerve, receives there a small filament from it.* It then rises a little, and enters the orbit at the internal extremity * Soemmering, Icones Oculi Humani. NERVUS TRIGEMINUS. 473 of the sphenoidal fissure; and, going forwards, next to the perios- teum of the upper part of the orbit, it enters into the superior ob- lique muscle of the eye, near its middle, and is distributed upon it. This nerve augments in volume as it advances towards its destination. SECT. V.--OF THE NERVUS MOTOR EXTERNUS. The Nervus Motor Externus, or sixth pair, having got into the cavernous sinus, is placed at the external side of the internal caro- tid artery, and adheres closely to it. It there sends off one or more filaments, which follow the internal carotid artery through its canal, and anastomose in their descent with a branch of the pterygoid nerve: the junction of these two forms the upper end of the great sympathetic nerve, and runs down to the superior cervi- cal ganglion of the sympathetic in two or more filaments generally. The sixth nerve enters the orbit through the sphenoid fissure, and is there closely connected with the nervus Motor oculi and the Nasal nerve. It penetrates into the substance of the rectus exter- nus muscle, and is entirely distributed upon it; with the exception that sometimes it sends a filament to the ophthalmic ganglion. SECT. VI.—OF THE NERVUS TRIGEMINUS. This nerve, having formed the ganglion of Gasser, (Plexus GlangUformis,) on the side of the petrous bone, then divides, as mentioned, into three large trunks, the foremost of which is the Ophthalmic Nerve: the second fasciculus is the Superior Maxil- lary; and the third the Inferior Maxillary Nerve. The Ophthalmic Nerve, or the first branch of the trigeminus, is smaller than either of the other two branches, and comes frontHhe superior part of the plexus gangliformis. It passes along the ex- ternal border of the cavernous sinus, and penetrates the orbit through the sphenoidal fissure, on the outer side of, and near the motor oculi. In its whole course it is united to the trochlearis nerve by close cellular membrane, and does not give off any ramifications before it reaches the orbit, with the exception of the filament sent to the trochlearis nerve. While engaged in the sphenoidal fissure it Vol. II.—41 474 NERVOUS SYSTEM. divides into three branches; the Nasal, the Lachrymal, and the Frontal. The Nasal branch of the ophthalmic, is between the other two in size. It ascends obliquely above the optic nerve to gain the in- ternal face of the orbit of the eye, and then passes forwards just below the superior oblique muscle, involved in a quantity of adi- pose matter. Shortly after its origin the nasal nerve detaches a branch (the ramus ciliaris) which, situated at the external margin of the optic nerve, runs into the ophthalmic or lenticular ganglion, and constitutes the long root; it then sends off one or more fila- ments, which, without communicating with this ganglion, pene- trate into the eyeball, and are amongst the ciliary nerves which have been described. The nasal nerve, continuing to pass forward along the internal paries of the orbit, when it reaches the anterior internal orbitary foramen, detaches through it the Internal nasal or ethmoidal branch, which, thus getting into the cavity of the cranium, goes along side of the crista galli, and passes into the nose through the fore- most hole of the cribriform plate;—then descends along the ante- rior part of the nose, on the outer side of the Schneiderian mem- brane, and is spent by ramifications upon the contiguous portions of the latter: some of the terminating branches reach the tip of the nose and the alse.* The nasal nerve, after the ethmoidal branch is sent off, is fre- quently called external nasal, or nervus infra-trochlearis. It con- tinues to advance along the under margin of the trochlearis muscle and gets to the trochlea, near which it divides into an upper and an under ramuscle; from them filaments proceed to the upper and under eyelids, to the lachrymal sac, the lachrymal caruncle, the tunLga conjunctiva, and the muscles on the root of the nose. These filaments anastomose with the terminating branches of the frontal nerve, the facial, and the infra-orbitary. According to Dr. G. Trasmondi,f of Rome, two filaments may be traced very dis- tinctly from the external nasal nerve to the tensor tarsi muscle of the lachrymal sac. They adhere to the muscle by means of eel- * * See Nerves of the Nose. t Intorno la scoperta di due nervi del Occhio umano ragguaglio del Dr. Giuseppe Trasmondi, Professore di Anatomia Practica nel ven. ospidale dclla Consolazione. Roma, 1823. NERVUS TRIGEMINUS. 475 lular structure, and pass on to its bifurcated extremities and to the puncta lachrymalia. The Frontal Nerve is the largest of the three branches of the ophthalmic. It proceeds forward between the levator palpebral superioris and the contiguous part of the orbit, and in this course is divided into two branches, the internal and the external frontal nerve. The former approaches the trochlea of the upper oblique muscle, and detaches a filament to join with one from the Nasal nerve. Other filaments are detached to the upper eyelid, some of which anastomose with filaments from the Lachrymal nerve. The internal branch of the frontal then issues from the orbit close by the trochlea, and, in ascending, is lost upon the occipito-fronta- lis, the corrugator supercilii, and the orbicularis muscle. The ex- ternal branch of the frontal issues from the orbit, through the su- pra-orbitary foramen. It quickly detaches a filament, which goes outwardly to anastomose with the facial; the remaining part of the nerve is distributed to the occipito-frontalis, to the corrugator su- percilii, to the integuments of the forehead, and to the scalp. This distribution, according to Bichat,is best followed by detaching the skin, muscles, and the periosteum from the cranium, from behind forwards as far as the orbit. The Lachrymal Branch of the ophthalmic nerve goes forwards along the external side of the orbit near the superior margin of the rectus externus muscle. In this course it sends off a filament through the spheno-maxillary fissure which unites with one from the second branch of the fifth pair; it afterwards sends off another filament, whicm*f>assing through a foramen in the malar bone, anastomoses with a filament of the facial nerve. What remains of the lachrymal nerve is then distributed by several filaments upon the lachrymal gland, the upper eyelid, and some of them reach the conjunctiva. Second Branch of the Trigeminus. The Second Branch of the Fifth Pair, (Nervus Maxillaris Su- perior,) arising from the middle of the plexus gangliformis, or gan- glion of Gasser, and also, in part, from the common trunk formed from the anterior and posterior roots of the trigeminus, gets from the cranium through the foramen rotundum of the sphenoid bone. 476 NERVOUS SYSTEM. While still in the cranium it sometimes forms an anastomosis, de- scribed by Laumonier, with the beginning of the sympathetic nerve, but generally it does not detach any filament till it reaches the pterygo-maxillary fossa. At a short distance after its exit from the cranium, it gives off a small filament, the Nervus Subcutaneus Malae, which ascends into the orbit through the spheno-maxillary fissure, and then di- vides. One of the branches, the malar, anastomoses with the lachrymal nerve, and leaves filaments with the lachrymal gland; it then gets, by one or more filaments, through the holes of the malar bone to the face, and terminates on the orbicularis muscle and the skin of the cheek, anastomosing with the extremities of the facial nerve. The other branch, the temporal, gets into the temporal fossa by penetrating the internal part of the malar bone, and, having anastomosed with a branch of the inferior maxillary nerve, it goes outwards and backwards, becomes superficial by penetrating the temporal aponeurosis, and terminates on the inte- guments of the temple, anastomosing there with the branches of the facial nerve. The superior maxillary then divides into two trunks much larger than the preceding, and of a volume nearly equal; the Infra-Orbi- tal and the Pterygo-Palatine. The Infra-Orbital (Nervus lnfra-Orbitalis) passes forwards, with a slight ascent, to the posterior part of the orbit, and enters the in- fra-orbitar canal. As it is about engaging in the latter, it detaches a considerable branch, the Posterior Dental. This branch de- scends a little distance, externally, along the posterior paries of the maxillary sinus, then penetrates into the cavity of the latter. It terminates by filaments, some of which supply the lining membrane of the antrum; others pass through the little canals leading to the three large grinders, and enter the roots of the lat- ter; others go to the corresponding gums. One branch goes along the outer side of the sinus to anastomose with the anterior dental nerve. The posterior dental, before it enters the bone, also de- taches a branch of some size, which winds around the tuberosity of the maxillary bone, and is spent upon the buccinator muscle and opon the gums. The infra-orbitary nerve afterwards, in its course through the canal, sends off the anterior dental nerves from one or more roots. Some of them detach fibres to the mucous membrane of the nose, NERVUS TRIGEMINUS. 477 where it covers the anterior part of the inferior turbinated bone. With this exception, they are distributed, through their appropriate canals in the bone, to the incisor and canine teeth, and to the cor- responding gums. The small molar teeth are most frequently supplied by an union of filaments, from the anterior and posterior dental nerves. The infra-orbitar nerve, on issuing from the infra-orbitar fora- men, is most frequently found already divided into several fas- ciculi, which may be classed into superior and into inferior. The former, called Palpebral, radiate, externally and internally, into filaments which supply the lower eyelid. One of these filaments may be traced to the end of the nose, where it anastomoses with the internal nasal branch of the ophthalmic; another, which termi- nates about the internal angle of the eye, anastomoses there with the external nasal nerve. Others of its terminating filaments anas- tomose with the extremities of the facial nerve on the eyelid. The inferior fasciculi are more numerous and large than the superior. They descend upon the face covered by the levator muscles of the upper lip, and from their distribution are called Labial. The most internal of these fasciculi terminate on the skin, the muscles, and the beginning of the mucous membrane of the nose, where they anastomose with the extremities of the internal nasal nerve. The middle fasciculi go to the muscles of the upper lip and the skin of the latter, and to its mucous glands. The external fasciculi go to the zygomatic muscles and to the contiguous skin. All the fore- going branches of the infra-orbitar nerve anastomose with the extremities of the facial, and are so minutely distributed to the skin and muscles of the face, that it would require, a very protracted description to point them out particularly. The Pterygopalatine Nerve (Nervus Pterygo-palatinus) de- scends, as a single or a double trunk, from its root to the outside of the spheno-palatine foramen, and there forms the ganglion of Meckel,* or the spheno-palatine ganglion, the existence of which is not constant. From this ganglion, or from the nerve itself pro- ceed several branches. A filament, described by Bock, is detached from it, which enters * Discovered by Meckel, 1749. 41* 478 NERVOUS SYSTEM. Into the sphenoidal sinus to be distributed on its lining membrane, and sometimes to anastomose with the motor externus oculi. Then arise the Spheno-palatine branches, which enter the nose through the spheno-palatine foramen, and are distributed upon the mucous membrane of its septum and turbinated portions, after the manner described in the account of the nose. The Vidian or Pterygoid Nerve (Nervus Vidianus, recurrens, pterygoideus) arises from the inferior part of the ganglion, and is a recurrent branch, which goes backwards through the pterygoid foramen of the sphenoid bone. From it there arise some filaments, which get to the mucous membrane about the anterior orifice of the Eustachian Tube, either through the spheno-palatine foramen, or by small foramina in the pterygoid process of the sphenoid bone. They are sometimes united into a single trunk, called pha- ryngeal, by Bock. The Vidian nerve, while still in its canal, then divides into two trunks, the superficial, and the deep petrous. The Superficial Petrous (Nervus Petrosus Superficialis) traverses the cartilaginous matter at the point of the petrous bone, in the anterior foramen lacerum of the basis of the cranium, gets there into the cavity of the latter, continues its progress backwards on the superior face of the petrous bone, in a gutter marked on the bone, and disappears through the Vidian foramen. It, in a short space, reaches the aqueduct of Fallopius, and then continues to adhere to the facial nerve till the latter almost reaches the stylo- mastoid foramen: it then abandons the facial nerve, and, as men- tioned in the account of the ear, traverses the tympanum under the name of chorda tympani; and, finally, emerging at the glenoid foramen, it runs to associate itself with the lingual branch of the trigeminus. The superficial petrous, in the early part of its course, at the point of the petrous bone, detaches one or more filaments to the sympathetic in the carotid canal. The Deep Petrous (Nervus Petrosus Profundus) is larger than the other. It also penetrates through the cartilaginous matter at the point of the petrous bone, and enters the cavity of the cranium under the dura mater. It then advances to the internal carotid artery, and anastomoses there with a filament from the motor ex- NERVUS TRIGEMINUS. 479 ternus or sixth nerve. This anastomosis as stated is commonly called the beginning of the sympathetic nerve. The Palatine Nerve (Nervus Palatinus) proceeds from the infe- rior part of the ganglion of Meckel, and gets to the soft palate of the mouth through the posterior palatine foramen. In this course, it detaches several filaments to the Schneiderian membrane, which reach it either through the spheno-palatine foramen, or by per- forating the nasal lamella of the palate bone. These are described in the account of the nose. The trunk of the palatine nerve, having reached the roof of the mouth, bends forwards, and is divided into many filaments, some of which are distributed along the gums of the upper jaw, others are distributed on the lining membrane of the hard palate and upon its mucous glands. There are two other nerves, which arise either immediately from the palatine, or from the ganglion of Meckel, and go to sup- ply the soft palate. They are called the smaller palatine. One of them, having proceeded for a short distance in the posterior palatine canal, departs from it in a. little canal of its own, which opens behind the hook of the internal pterygoid process. It then radiates into filaments, which supply the tonsil gland and the mus* cular and membranous structure of the soft palate. The other smaller palatine also traverses, after the same manner, its own canal, and is likewise distributed to the tonsil gland and to the soft palate. Third Branch of the Trigeminus.. The Third Branch of the Trigeminus (Nervus Infra-maxillaris) is the largest of the three. It arises from the posterior inferior part of the ganglion of Gasser, and having anastomosed with the cavernous ganglion of the sympathetic nerve by filaments, which are not constant, it emerges from the cranium through the foramen ovale of the sphenoid bone. A portion of this branch, as men- tioned, does not enter into the composition of the ganglion of Gasser, but proceeds immediately from the pons varolii.. The inferior maxillary nerve, at its exit from the foramen ovale, is covered by the pterygoideus externus muscle, and commonly divides there into two branches, one anterior and the other poste- rior or else sends off two sets of branches—the first for the mus- 480 NERVOUS SYSTEM. cles of mastication—and the second set for the lower jaw and tongue. The Anterior Branch, or set, which is much smaller than the other, radiates into five fasciculi; the masseter nerve; the two temporal; the buccal; and the pterygoid. a. The Masseter Nerve is directed horizontally outwards and backwards, along the external margin of the pterygoideus exter- nus, and in front of the temporo-maxillary articulation: it leaves some filaments with the latter, and then passing between the inser- tion of the temporal and of the external pterygoid muscle, over the concave edge of the bone, between the condyle and the coronoid process of the lower jaw, it penetrates into the substance of the masseter muscle, and is distributed through it. b. The two Temporal branches arise by a common fasciculus, but sometimes differently. They pass outwards, horizontally, be- tween the external pterygoid muscle and zygomatic fossa. They then ascend on the side of the temporal bone, between it and the temporal muscle, and are distributed through the latter by a great number of filaments. Some of these filaments penetrate the apo- neurosis, to anastomose with the superficial temporal nerves. And one of them anastomoses with the Temporal Branch of the Sub- cutaneous Malse, in the temporal fossa. c. The Buccal Branch is the largest of the five. It advances between the pterygoid muscles, to which it furnishes a few fila- ments, and then descends between the temporal and external pterygoid muscle to the posterior part of the buccinator. It is principally distributed on the latter, upon the buccal glands, and the corresponding part of the lining membrane of the mouth. Some of its branches advance under the integuments of the face, as far as the commissure of the lips to the muscles there, and - anastomose with the facial nerve. d. The Pterygoid Branch is the smallest, and is distributed principally on the internal pterygoid muscle. The Posterior Branch of the inferior maxillary nerve is so large, that it looks like a continuation of the trunk. It is.divided into the superficial, temporal; the inferior dental, and the lingual nerve. a. The Superficial Temporal Branch is formed by an union of two fasciculi, between which passes the middle artery of the dura NERVUS TRIGEMINUS. 481 mater; the inferior of these fasciculi comes from the inferior den- tal nerve. The nerve is directed outwards, and winds horizontally around the posterior face of the neck of the condyle of the lower jaw, between it and the meatus auditorius externus. It is there divided into-several small fasciculi, two or three of which pene- trate into the substance of the parotid gland, and anastomose with the facial nerve or its ramifications; one or two others go back- wards, penetrate between the bony and the cartilaginous meatus to the auditory canal, and are dispersed by fine filaments upon the concha, and the meatus externus. According to Bock, one of these filaments supplies the membrane of the tympanum, and also anas- tomoses with the chorda tympani. Another branch of the super- ficial temporal, which is the largest of any, traverses the parotid gland, and thereby becomes superficial, just in front of the external ear. It then divides into filaments, which follow the course of the superficial temporal artery, and thereby supply the middle part of the integuments on the side of the head. It anastomoses with the filaments of the frontal nerve, and with those of the occipital. b. The Inferior Dental Nerve is placed between the other two branches, and exceeds them in size. It descends between the two pterygoid muscles, towards the posterior mental foramen. Just above the latter it detaches a small branch, the mylo-hyoid, which occupies the small gutter on the bone leading downward from the posterior mental foramen. This branch sends a filament to the submaxillary gland, then passes between the anterior belly of the digastric muscle and the mylo-hyoideus, to both of which it gives filaments, and finally winding over the base of the lower jaw in front, it is lost upon the muscles of the chin. The inferior dental nerve then enters the posterior mental fora- men, and divides into two branches, which run parallel with one another through the canal in the middle of the spongy structure of the bone, and send a great number of anastomotic filaments to each other. One of the branches, the dental, properly speaking, as it passes along- the ends of the roots of the teeth, detaches a filament to each root, from the last grinder to the first incisor tooth inclusively: it also sends a filament to the gum intermediate to every two teeth. All of these filaments arise from the dental nerve, at places behind the points of destination; so that they have 482 NERVOUS SYSTEM. before reaching the latter, to run forwards and upwards through little canals in the cellular structure of the bone. The other branch of the inferior dental nerve is the mental; it does not advance so far forward in the bone as the preceding, but issues from it at the anterior mental foramen, and immediately is divided into two fasciculi, the inferior labial nerves. The internal fasciculus is distributed by filaments upon the muscles of the chin and lower lip, the contiguous lining membrane of the mouth and the labial glands. The external fasciculus rises upwards and is distributed on the muscular structure, about the under part of the commissure of the lip, and to the contiguous lining membrane and glands of the mouth. c. The Lingual Nerve descends in company with the inferior dental, but in advance of it, and diverging slightly. While be- tween the two pterygoid muscles it receives the chorda tympani at a very acute angle. It then passes towards the side of the root of the tongue, deeply concealed by the angle of the lower jaw, and above the submaxillary gland, to which it gives some consi- derable filaments. A ganglion, called the Submaxillary, is formed here by one or more filaments of the lingual nerve, and from this ganglion pro- ceed filaments to the submaxillary gland. The submaxillary ganglion is so named from being placed upon the submaxillary gland. It is very small, and is considered by some to be derived from the Chorda Tympani, which they say, after joining the gustatory nerve, leaves it and unites to or forms this ganglion, with the assistance of some two or more filaments from the gustatory nerve, and one. or two from the cervical por- tion of the Sympathetic. The ganglion also detaches forwards filaments to join the gustatory nerve, and some in company with the duct of the submaxillary gland. The lingual nerve then proceeds forwards between the mylo- hyoideus and the hyo-glossus muscle, and between the sublingual gland and the latter, having in front of it the excretory duct of the submaxillary gland. It anastomoses frequently with the hypo- glossal nerve, sends several filaments to the lining membrane of the mouth, below the tongue, and to the sublingual gland. It then divides, or radiates, into seven or eight fasciculi, which run up- wards and forwards on the side of the stylo-glossus muscle, and NERVUS FACIALIS. 483 the genio-hyo-glossus, and are finally spent by very fine filaments penetrating into the structure of the papillae, on the upper surface of the tongue. The third branch of the trigeminus, according to Dr. Arnold of Heidelburg, also forms, by several filaments, a ganglion, called Otic, near the foramen ovale. This ganglion is below the spinous pro- cess of the sphenoid bone, and sends off several filaments: one contributes to the nervous anastomosis of Jacobson,* which con- nects the superficial petrous, sympathetic, and glosso-pharyngeal nerves: another filament passes to the tensor tympani, and is dis- tributed upon it. Other filaments join the superficial temporal nerve: that part of it which supplies the membrana tympani. There is also an anastomosis with the portio mollis, f SECT. VII.—NERVUS FACIALIS. The Facial Nerve (Nervus Facialis; portio dura septimi; par septimum) having gained the meatus auditorius internus, passes in front of the auditory nerve into the canal of Fallopius, and wind- ing through it, around the tympanum, it emerges at the stylo-mas- toid foramen, having sent in this course one or more filaments to the muscles of the little bones of the tympanum. Afterwards, the facial nerve gives off several branches, which are distributed as follows:— a. The Posterior Auricular (Auricularis Posterior) arises near the stylo-mastoid foramen, as stated in the account of the Nerves of the Ear; and having sent several filaments into the mastoid process, it winds over the anterior face of the base of the latter, and divides into two fasciculi. The anterior is distributed in fila- ments upon the back of the external ear, the cartilaginous meatus, and the posterior auris muscle; the posterior ascends upon the mastoid portion of the temporal bone to the posterior belly of the occipito-frontalis muscle, and is spent by filaments to the latter, and to the corresponding integuments, anastomosing likewise with ramifications of the occipital nerve. b. The facial nerve then detaches filaments to the muscles of * This nervous anatomosis is described, page 470, article Vidian Nerve. t Am. Med. Jour., vol. v., p. 192. 484 NERVOUS SYSTEM. the styloid process, and to the posterior belly of the digastric mus- cle. It also sends filaments of anastomosis to the superior part of the sympathetic nerve; to the cutaneous cervical; and to ramifi- cations of the glosso-pharyngeal, of the pneumo-gastric, and of the accessory. The facial nerve, having given off the foregoing filaments and branches, penetrates downwards and forwards into the substance of the parotid gland, where it is divided into a number of branches, varying from two to five, which form a plexus by their anasto- mosis. This plexus is re-enforced, as mentioned, by branches from the superficial temporal-of the inferior maxillary, which wind around the neck of the lower jaw. It is then distributed to the side of the face in radiating clusters or columns of filaments, called the temporo-facial, the buccal, and the cervico-facial. The Temporo-Facial Nerves, or Branches, are hid, for some distance, in the upper part of the parotid gland, which they tra- verse below the neck of the lower jaw. They divide into fila- ments, some of which go to the temple, and others to the cheek. The temporal branches are commonly two or three in number; they leave filaments with the parotid gland, mount over the zygo- ma, and are distributed to the anterior auris muscle, to the outer section of the orbicularis palpebrarum, and to the integuments of the temple; they anastomose in their distribution with each other, with the superficial and deep temporal branches of the inferior maxillary nerve, and with the frontal and lachrymal branches of the ophthalmic. The malar branches are primitively, also, two or three in number: they cross the malar bone, dividing, subdividing, and anastomosing again, and are spent upon the integuments and muscles of this part of the face. They also anastomose with fila- ments of the lachrymal nerve, and with those of the infra-orbitar nerve. The Buccal Branches are three in number, sometimes two only ; and pass across the masseter muscle under the skin. The supe- rior anastomoses with the temporo-facial, and the inferior with the cervico-facial. The buccal branches supply the skin and muscles of the face intermediate to the eye and to the lower lip. The nu- merous filaments into which they divide anastomose frequently with each other, and with the branches of the fifth pair, which ap- pear about the same parts, as the external and internal nasal nerve, NERVUS HYPOGLOSSUS. 485 the infra-orbitar, and so on. The middle buccal is parallel with the duct of the parotid gland, and adheres to it. The Cervico-Facial Branch descends in the substance of the parotid gland, behind the ramus of the lower jaw; when it reaches the angle of the latter it goes obliquely forwards, beneath the pla- tysma myodes muscle. Though it sends off' many fasciculi, they may be referred to two divisions, a superior and an inferior. The first crosses the inferior part of the masseter muscle, and may be traced in its numerous distribution of filaments, to the integuments and muscles lying upon the body of the lower jaw. These fila- ments anastomose with each other, and with the mental branches of the inferior dental nerve. The inferior division supplies the skin and the platysma myodes muscle on the upper part of the neck along the base of the lower jaw. Its filaments are joined by several coming from the anterior fasciculus of the third cervical nerve. The anastomoses of the facial nerve, derived from its own branches and from those of the trigeminus, which reach the face, are entirely too numerous for a detailed description of them; it, indeed, appears unnecessary to extend the latter beyond a certain point. The most satisfactory account has been published by Meckel.* SECT. VIII.--NERVUS HYPOGLOSSUS. The Hypoglossal Nerve, {Nervus Hypoglossus, Lingualis,) having arisen from the medulla oblongata, and escaped from the cranium through the anterior condyloid foramen, adheres closely for an inch to the pneumogastric nerve. It descends between the external carotid artery and the internal jugular vein, the latter being behind the other; and then winds over the carotid, externally, just below the origin of the occipital artery. It is there covered by the posterior belly of the digastricus and by the stylo-hyoideus. It then passes forwards beneath the external jugular vein, and lower down somewhat than the tendon of the digastric muscle, and, finally, ascends to the tongue, being covered or concealed by the mylo-hyoideus muscle. The nerve in this course, from the exter- J. F. Meckel, de Nervis Faciei, Mem. de 1'Acad. dcs S. de Berlin, 1751, Caldani, Tab. 247. Vol. II.—42 486 NERVOUS SYSTEM. nal carotid to the tongue, forms a remarkable curve, the convex- ity of which is downwards. The Hypoglossal, while adhering to the pneumo-gastric, com- monly leaves a few filaments with it. As it crosses the external carotid, it detaches a large branch, the Ramus Descendens Noni, which goes down the neck, along the sheath of the carotid artery and the internal jugular vein, in front of the latter. The ramus descendens has been beautifully figured by Scarpa, in his Plates of the Nerves. According to him, when it has got about half way down the neck, but still resting on the sheath of the vessels, it detaches, in front, two filaments, which, after the course of an inch forwards, unite, and then separate again to be distributed to the upper ends of the omo-hyoid and sterno-hyoid muscles. The descendens noni then forms, an inch lower down, a small gangliform plexus, resting upon the sheath of the great ves- sels of the neck, under the omo-hyoid muscle. This plexus is joined by two fasciculi, which descend from the first and second cervical nerves, and from it proceed downwards, and backwards, two filaments, which join the phrenic nerve; also, one to the lower part of the omo-hyoid muscle; and three or more, which are di- vided and distributed upon the sternohyoid and thyroid muscles, and upon the muscles of the larynx. Meckel states, that some of these ramifications on the left side principally, penetrate to the thorax, and reach the pericardium. The hypoglossal nerve, having sent off the ramus descendens, reaches the external face of the hyo-glossus muscle, and is there concealed by the mylo-hyoideus, where it gives filaments to the muscles of the larynx, to the hyo-glossus, genio-hyoideus, and ge- nio-hyo-glossus. These filaments anastomose frequently with each other, and in two or three places at the anterior part of the tongue with the lingual branch of the nervus trigeminus. After these branches are given off, the trunk of the hypo-glossal nerve pene- trates into the substance of the genio-hyo-glossus muscle, and ex- tends itself near its fellow, and not far from the middle line of the tongue to the point of the latter. It first distributes filaments near the posterior part of the tongue, and then, successively, as far as its anterior extremity. They cannot be traced to the papillas, but are lost upon the muscular structure. It is a general opinion among anatomists that the hypo-glossal nerve is only intended to excite the muscular movements of the NERVUS ACCESSORIUS. 487 tongue. The opinion is founded upon the circumstance of its fila- ments not reaching the papillae, whereas those of the lingual branch of the trigeminus do. Colombo narrates a case, in which there was a congenital privation of taste, where the lingual branch of the trigeminus-was distributed upon the occiput instead of upon the tongue, which goes far to prove the difference of function in the two nerves. SECT. IX.--NERVUS ACCESSORIUS. The Accessory Nerve, (Nervus Accessorius Willisii,) having arisen, as described from the cervical medulla and the medulla oblongata, is directed, outwards to the posterior foramen lacerum, in company with the pneumogastric or par vagum. Sometimes it is separated from it in its passage through the base of the cranium, by a thin partition of dura mater; on other occasions merely by a fold of the tunica arachnoidea: but at the inferior part of this fora- men it adheres so closely to the par vagum that the two look like but one nerve. Near its exit it is divided into two fasciculi. The internal gives off one or two filaments, which, joining a branch of the par va- gum, forms the superior pharyngeal nerve; the internal branch then descends, and being divided into several branches, they, suc- cessively, join the upper part of the par vagum. The external fasciculus descends for two inches behind the internal jugular vein, being placed first of all between it and the occipital artery, but sub- sequently between the vein and the sterno-mastoid muscle. It then pierces this muscle about one-third of the length of the latter from its superior extremity, and leaves filaments in it which anastomose with some from the third cervical nerve. In continuing its descent, it is re-enforced and augmented considerably in volume, by branches from the second and third cervical. Having reached the anterior margin of the trapezius muscle, it then distributes itself to the latter, by internal and by external branches. The spinal accessory and the par vagum are compared by Goerres* to the anterior and posterior roots of a spinal nerve. The enlargement of the vagum in the foramen lacerum being con- sidered ganglionic,, is in favour of the analogy. * Muller, p. 658. 488 NERVOUS SYSTEM. SECT. X.—NERVUS GLOSSO-PHARYNGEUS. The Glosso-Pharyngeal Nerve (Nervus Glosso-Pharyngeus,) though commonly considered as distinct from the pneumogastric, has so many connexions with it, both at its root, in its course through the posterior foramen lacerum, and in its distribution, that it seems like a part or branch of the same. At the base of the cranium in front of the pneumogastric, it forms, according to some anatomists,* a ganglion of five or six lines in length, (Ganglion Petrosum,) the existence of which was denied by Bichat. From this ganglion proceeds a filament,f which penetrates into the tym- panum and divides into two branches; one of them ascends along the promontory, having detached a filament to the membrane of the foramen rotundum: it then penetrates the petrous bone; and anastomoses or joins with the superficial petrous nerve. The other branch passes below the bony Eustachian Tube, and, gaining the carotid canal, anastomoses there with the Sympathetic Nerve. This is part of the anastomosis of Jacobson, and is also described in the account of the Vidian Nerve.J The ganglion also gives off other filaments, which join the pneumogastric nerve, the accessory and the sympathetic. On issuing from the posterior foramen lacerum, the glosso- pharyngeal is separated from the pneumogastrie by the internal jugular vein. It is then directed downwards and forwards between the internal carotid and the stylo-pharyngeus muscle, afterwards between the latter and the stylo-glossus; it follows the direction of the latter to the side of the root of the tongue. In this course, it sends off many filaments. Shortly after leaving the cranium, it detaches one backwards to the digastric branch of the facial, and another to the pneumogastric. It then sends off two filaments, which descend along the internal and common carotid, and are divided into several branches, some of which anastomose with the pharyngeal branch of the pneumogastric, others descend * Anderiach and Huber. This ganglion is considered by some as commencing before the nerve penetrates the foramen lacerum ; others, as Miiller, say that there is at this point a ganglion besides the lower one, but that all the fibres do not concu r to form it. t Rosenmuller, Jacobson, Lobstein. t See Nerves of Organ of Hearing, p. 470. NERVUS PNEUMOGASTRICUS. 489 on the common carotid with filaments from the pharyngeal branch, and being joined by two or three small twigs from the superior cervical ganglion, they reach the lower part of the neck, and concur in the forming of the superficial cardiac nerve. Farther down after the origin of these branches the glosso-pharyngeal de- taches two or three filaments to the stylo-pharyngeus muscle, as well as some to the upper and middle constrictors of the pharynx, to the pharyngeal plexus of the sympathetic and pneumogastric, and to the posterior lateral and superficial part of the tongue. The glosso-pharyngeal nerve having got between the stylo and hyo-glossus muscles, is placed intermediately to the lingual branch of the fifth pair and hypo-glossal nerve. Some of its branches then go to the integuments of the base of the tongue, to its mucous glands, large papillae, and may be traced to the mucous membrane of the soft palate, to the amygdalae, and to the covering membrane of the epiglottis. Others go into the muscles of the tongue,.and. others may be traced along the external margin of the tongue, beneath its mucous membrane for some distance. Scarpa has delineated a remarkable plexus, which he denominates Circulus Tonsillaris Anderschii or Anastomosis Plexuosa, formed by these several filaments and by branches of the lingual, on the side of the rpot of the tongue, at the base of the tonsil gland. SECT. XI.—NERVUS PNEUMOGASTRICUS. The Pneumogastric Nerve (Nervus Pneumogastricus, Vagus* Par Octamm, Decimum of Andersach,) at its exit from the cra- nium through the posterior foramen lacerum, in front of the in- ternal jugular vein, is closely united to the hypo-glossal, glosso- pharyngeal, and accessory nerves, by compact cellular substance.. It is first placed in front of the hypo-glossal nerve, but, in a short space, gets.behind it, and is also separated from the glosso-pharyn- geal by the internal jugular vein. Opposite the transverse process of the atlas, it leaves the hypo-glossal nerve, and assumes a posi- tion between the internal carotid and the internal jugular, on the vertebral side of these vessels, and is enveloped in their sheath of dense cellular substance. It maintains this relative position along the common carotid to the root of the neck. At the latter place,.the pneumogastric of the right side goes in 42* 490 NERVOUS SYSTEM. front of the subclavian artery, near its root, but on the left side it crosses the root of the left subclavian artery, and the arch of the aorta to the left of the origin of the left carotid. In getting fairly into the cavity of the thorax, it is directed backwards and down- wards from these points towards the posterior face of the bronchus, between it and the pleura. It then abandons the bronchus, and applies itself to the oesophagus, and follows it through the dia- phragm to the stomach. The nerve of the left side, in its course along the oesophagus, is on the front surface of the latter, and the nerve of the right side, on its posterior surface. The pneumogastric anastomoses with the accessory while pass- ing through the foramen lacerum posterius. Somewhat lower down, it also anastomoses with the glosso-pharyngeal and with the superior cervical ganglion of the sympathetic. The branches which it afterwards sends, off, go to the neck, to the viscera of the thorax, and to those of the abdomen, after the following man- ner :— A. Cervical Branches. The Superior Pharyngeal Nerve (Ra- mus Pharyngeus) arises just below the preceding anastomosis. It is directed downwards on the internal face of the internal carotid, and having sent an anastomotic filament to the glosso-pharyngeal nerve, it forms on the middle constrictor of the pharynx, the pha- ryngeal plexus which is re-enforced by filaments from the superior cervical ganglion of the sympathetic, from the glosso-pharyngeal, and from the superior laryngeal nerve. The filaments departing from this plexus, are spent principally upon the middle constrictor, but a few of them also go to the superior constrictor; and others, descending along the primitive carotid, anastomose with.ramifica- tions from the glosso-pharyngeal, and from the superficial cardiac nerve. A filament, called the inferior pharyngeal, sometimes pro- ceeds from the pneumogastric a little below the other, and also is spent upon the pharynx. The pneumogastric, at the place where it detaches these pharyn- geal branches, or a little above them, becomes softened in its tex- ture, enlarges somewhat, and has the fasciculi which compose it moderately separated by a sort of red gelatinous substance inter- posed between them. This portion is its gangliform plexus, and into it is joined one or more branches from the accessory nerve. The Superior Laryngeal Nerve (Nervus Laryngeus Superior) PNEUMOGASTRIC NERVE. 491 arises from the gangliform plexus. It descends between the inter- nal carotid and the superior cervical ganglion, anastomosing on the way with the latter, with the pharyngeal plexus, and the hypo- glossal nerve; it then divides into an external and an internal laryngeal branch. The former sends its filaments to the muscles situated on the fore part of the thyroid cartilage; to the thyroid gland; and some of them penetrate through the crico-thyroid membrane to the lining membrane of the larynx. The internal laryngeal branch is placed above the other; it is directed towards the middle thyreo-hyoid ligament, which it penetrates and then begins to ramify. Some of the branches go to the epiglottis car- tilage, its covering membrane, and the adjacent portion of the lining membrane of the pharynx. Other branches are distributed to the small muscles which move the arytenoid cartilages, and to the lining membrane of the larynx. The filaments which go to the epiglottis have an arrangement indicated by Bichat; that of going into the foramina which perforate it, but they cannot be traced farther. The pneumogastric afterwards does not send off any regular branches till it reaches the lower part of the neck. It then de- taches two or three filaments, (rami cardiaci,) which, on the right side, have their roots about an inch above the subclavian artery, and on the left side, an inch lower down. On the right side, they descend along the subclavian and the arteria innominata, on the left along the left carotid; they reach the arch of the aorta, and in their course, as well as there, anastomose very freely with the superficial cardiac nerve. The rami cardiaci are frequently more abundant on the right side than on the left. The Inferior Laryngeal Nerve (Nervus Laryngeus Inferior, Recurrens) is a considerable branch of the pneumogastric, which comes off next to the cardiac branches. On the right side it arises immediately after the trunk has passed between the subclavian artery and the subclavian vein. It then winds around the subcla- vian artery so as to retain the latter in its loop; having thus got behind the artery, it then ascends towards the larynx, on the side of the trachea, covered by the common carotid, and by the infe- rior thyroid artery. In this course the inferior laryngeal nerve detaches the following branches: 1. From the convexity of its loop it sends filaments to 492 NERVOUS SYSTEM. the assistance of the cardiac branches just spoken of, arising from the pneumogastric, and to those eomi.r.g fr0m the inferior cervical ganglion of the sympathetic. 2. It detaches the pulmonary branches, the origin of which is complicated with the plexus of nerves existing about their roots; these descend in front of the trachea, reach the pulmonary artery, and follow its ramifications into the lungs; some of the filaments, however, go to the cardiac plexus. 3. The inferior laryngeal then sends many filaments to the oesophagus; 4. Branches which go to the inferior part of the thyroid gland; 5. Filaments to the trachea, some of which pene- trate the membrane on its posterior part, others go between the cartilages; they are then distributed to the lining membrane and to the mucous glands of the part. 6. The inferior laryngeal nerve is then distributed in branches to the inferior constrictor of the pharynx and its lining membrane, but the most of its terminating. filaments penetrate to the larynx, between the thyroid and the cricoid cartilage, and are lost upon the lining membrane of the larynx, and upon the small muscles which move the arytenoid cartilages. These terminating filaments anastomose with such as come from the superior laryngeal nerve. It is generally stated by anatomists that the distribution of the inferior laryngeal nerve to the larynx, is confined to the thyreo- arytenoid, and posterior and lateral crico-arytenoid muscles. Mr., G. Rainy states, in the London Medical Gazette, that he has re- peatedly traced its filaments, also, to the transverse and oblique arytenoid.* The recurrent of the left side forms a much larger loop than the other, and arises lower down, inasmuch as it has to wind around the arch of the aorta, at the origin of the left subcla- vian arterv: with some inconsiderable exceptions, its course and distribution afterwards are precisely the same with those of the nerve of the right side. B. The Thoracic Branches of the pneumogastric are as follow :. The inferior tracheal nerves come from it just below the recur- rent: they are five or six in number; some of them go in front of the trachea and bronchus, and others behind them. They are complicated by anastomoses with the branches of the recurrent nerve, and with those of the inferior cervical ganglion, and form * Am. Med. Journ , vol. iv.,. p. 198.- PNEUMOGASTRIC NERVE. 493 a small plexus, denominated the anterior pulmonary, which lies upon the front of the root of the lung, and has its filaments fol- lowing the branches of the pulmonary artery through the lung. The posterior filaments supply the structure of the bronchus by penetrating it, and some of them go to join the posterior pulmonary plexus. As the pneumogastric gets behind the trachea and the bronchus, it is sensibly enlarged and somewhat flattened, the cohesion of its fasciculi being somewhat looser. Several filaments depart there from it, which form an intertexture with each other; some of them pass inwards, to be distributed on the bronchus, trachea, and oesophagus. Others, which are given off as the nerve lies upon the posterior face of the root of the lung, amounting to six or seven in number, but being of various sizes, run transversely out- wards, and form an intertexture with one another. The latter are joined by filaments from the inferior cervical and the first dorsal ganglion of the sympathetic, and thus constitute the poste- rior pulmonary plexus. The filaments from this plexus follow the distribution of the bronchus, and, according to Bichat, are all destined to the mucous membrane and the mucous glands of the lung; as they may be traced piercing successively the ramifica- tions of the bronchus, in order to reach its lining membrane. On the right side, the par vagum, while furnishing the pulmo- nary plexus, and for some distance lower down, is divided into from four to six considerable fasciculi, which form with each other a plexus or series of anastomoses, having very large meshes, and from which proceed many filaments to the oesophagus. After- wards these fasciculi are assembled into a single cord, which proceeds on the posterior face of the oesophagus, along with it into the abdomen. On the left side, the par vagum, after forming the posterior pul- monary plexus, is split into two or three fasciculi; which likewise furnish branches to the oesophagus, and unite to form a single cord, which proceeds on the front surface of the oesophagus, along with it into the abdomen. The two nerves, while descending in this way, send frequent anastomotic filaments to each other, and to the oesophagus. C. In the Abdomen the par vagum is distributed as follows: Filaments are sent from each nerve, which form a plexus around 494 NERVOUS SYSTEM. the cardiac orifice of the stomach. The right nerve is then divided into many branches; some are distributed on the posterior face of the stomach, others go along the lesser curvature of this viscus, and reach thereby the pylorus, where they anastomose with fila- ments from the left nerve, and from the gastric plexus of the sym- pathetic ; others go behind the stomach to join the solar plexus, and are blended with the latter in its distribution to the liver, vena por- tarum, duodenum, and pancreas. The left par vagum, being placed in front of the cardia, is resolved into several radiating fila- ments or fasciculi, some of which supply the anterior face of the stomach, others go along its lesser curvature to the pylorus, to anastomose with the right nerve and the gastric branches of the sympathetic, and are finally blended, after the same manner as the preceding, with the solar plexus. CHAPTER II, Of the Sympathetic Nerve.* The Sympathetic Nerve (Nervus Sympalheticus Magnus, inter- costalis Maximus, Ganglicsus,) differs, in a great number of respects, from every other nerve of the body; and if we were actuated only by its peculiarities, with Bichat, Meckel, and others, we might, with great propriety, set it apart as something having a claim to an insulated description and location. The dissection of it, how- ever, is so much blended with that of the par vagum, that the de- scriptions of the two go best hand in hand, and are, therefore, most conveniently studied together. This nerve consists in a series or chain of ganglions, extending from the base of the cranium to the lower end of the sacrum. They are placed on the lateral part of the bodies of the vertebra?, are united to each other by intermediate nervous cords, and send off continually filaments to the adjacent organs. With the excep- tion of the neck, there is a ganglion for each intervertebral space, * Anton. Scarpa. Tabul. Neurolog. THE SYMPATHETIC NERVE. AQfr both of the true vertebra? and sacrum. Besides these ganglions, there are others which are situated around the trunks of some of the large vessels of the abdomen.* The superior extremity of the sympathetic nerve, opposite to the transverse process of the second cervical vertebra, and behind the internal carotid artery, forms a ganglion, which, for the pur- pose of description, may be considered as the first of the series. This ganglion is the superior cervical. The nervus motor externus oculi, in passing through the caver- nous sinus, and the Vidian nerve, in passing by the point of the petrous bone, both send a filament downwards through the carotid canal; which two filaments unite to form a single cord, that runs into the superior extremity of this ganglion. The filament from the Vidian nerve is, as mentioned, the deep petrous nerve. The common view taken by anatomists of this nervous connexion is. that it is the beginning of the sympathetic, though, by Bichat, it is described as the termination, or one of its extremities. The dis- tinction, though important physiologically, is less so when the ob- ject is simply to describe the course and anatomical relations of this nerve, as they may be equally understood by either mode of description. The branch from the deep Petrous most frequently forms, on the external face of the internal carotid, in the cavernous sinus, or more generally in the carotid canal, a ganglion, (Ganglion Caver- nosum, Caroticum,) discovered by Laumonier. Some anatomists consider this ganglion to arise from one or more filaments, from the motor externus. This ganglion, to say the most of it, is an elongated flattened enlargement of the trunk of the deep petrous in many subjects, if not in most, scarcely meriting the name of gan- glion.f From the ganglion cavernosum, it has, of late, been ascer- tained that filaments may be traced to the ganglion of Gasser, (Plexus Gangliformis,) of the trigeminus, to the pituitary gland, to the infundibulum ; and, moreover, a fasciculus which, accord- ing to H. Cloquet, forms a plexus around the ophthalmic artery, * In the ganglia of the sympathetic, it is doubtful, whether the separate nervous filaments really unite, or keep distinct. t M. Lobstein, in his Essay on the Sympathetic, (Paris, 1823,) a work of much merit, has also attributed this ganglion to the deep petrous nerve, in which I thought for many years he was mistaken, though renewed observations have now convinced me of his correctness. 49£ NERVOUS SYSTEM. and may be traced along all its branches, even the central artery of the retina. This plexus anastomoses with the lenticular gan- glion, and consequently establishes a direct nervous communica- tion between the sympathetic, and the first branch of the fifth pair. The knowledge of this connexion has caused anatomists to locate the lenticular ganglion and the ciliary nerves in the ganglionic system of the sympathetic, as forming a part of the latter. From the ganglion ofLaumonier may also be traced a filament, which, attending the carotid in its ascent by the sella turcica, fol- lows also the anterior artery of the brain, or arteria callosa, and having reached the anterior communicating artery, it runs into a ganglion on the middle of this artery, the ganglion being common to it and the nerve of the opposite side. This is the Ganglion of Ribes, and establishes for the extreme upper end of the two sym- pathetics an anastomosis, or connexion on the same principle that the two lower ends communicate by an anastomosis in front of the os coccygis. The sympathetic, in descending the neck, is placed behind the carotid artery and internal jugular vein. It is commonly said to be enclosed in the sheath of these great vessels, but ihe statement is loose and inaccurate, as it is fastened to the front surface of the longus colli muscle by cellular substance distinct from the sheath, as may be manifested by pushing a knife handle between them and raising up the sheath. The cord which comes down from the carotid canal is close to the pneumogastric and hypoglossal nerves. Having formed the first cervical ganglion, it descends as mentioned; and, opposite to the space between the fifth and sixth cervical vertebrae, it is again enlarged into the Middle Cervical Ganglion, which is much smaller and more irregular than the first. The sympathetic is then traced with some difficulty, in conse- quence of the numerous branches coming from it; but, with atten- tion, a trunk may be found as the continuation of it. This trunk passes to the interval between the head of the first rib and the transverse process of the last cervical vertebra, and there en- larges into another ganglion, called Inferior Cervical or First Dorsal. To understand well the connexions of the sympathetic in the neck, each of the cervical ganglions must be studied particularly. THE SYMPATHETIC NERVE. 497 1st. The Superior Cervical Ganglion varies considerably in its extent; commencing very generally opposite to the second cervi- cal vertebra, it is sometimes elongated to the lower part of the third and even of the fourth. In cases of unusual elongation, it is smaller than in others. . It sends off, from its external margin, several filaments, about four, which cross the anterior face of the rectus anticus major muscle, and terminate by anastomosing with the anterior fasci- culus of the occipital nerve and of the first three cervical: when the ganglion is short, the two lower filaments come from the sym- pathetic below it, instead of from the ganglion. Several filaments also proceed from this ganglion to the conti- guous muscles on the vertebral column, to the pharynx, to the larynx, and to the thyroid gland. This ganglion also sends off what are called its Anterior branches, which are peculiar for their reddish colour and for their softness; the latter quality has obtained for them the name of Nervi Molles. They may be referred, by their position, to three orders. The superior ascend to anastomose with the" pneumogas- tric, hypoglossal, and facial nerves^ near their exit from the cra- nium. The middle are two or three in number, but immediately divide into many filaments, forming the carotid plexus by assist- ance from the pneumogastric, glossopharyngeal, and facial nerves. Some of the branches of this plexus descend behind the primitive carotid, at the place of its bifurcation, and accompany it to its origin, continually interlacing with each other. Others surround, after the same manner, the external carotid, and subdivide into a plexus for each of its branches, so that very fine filaments may be traced along the superior thyroidal, the lingual, facial, occipital, and temporal arteries. These nerves are, for the most part, diffi- cult to trace, from their extreme tenuity. The primitive branches, from which these plexuses come, are sometimes previously united into a small ganglion, which serves as a common centre to all these nervous irradiations. The third order of anterior branches amounting to from four to six, come either from the ganglion or from the sympathetic just below it. A cord formed by their union, called the Superficial Cardiac Nerve, descends on the external side of the primitive carotid, anastomosing with filaments from the pneumogastric and from the descendens noni. It gives small ra^ mifications to the contiguous parts, as to the pharynx, oesophagus, Vol. II.—43 498# NERVOUS SYSTEM. the sterno-hyoid and thyroid muscles. It terminates in the lower part of the neck, by detaching anastomosing branches to the branches of the recurrent nerve; some of them also go along the inferior thyroid artery to the thyroid gland. What remains of it is lost in the middle cardiac nerve; for it cannot be traced, in an insulated and distinct manner, to the heart; from which cause its appellation is objectionable. 2. The Middle Cervical Ganglion, placed intermediately to the fifth and sixth cervical vertebrae, upon the longus colli muscle, is there concealed by the common carotid, the internal jugular vein, and the pneumogastric nerve. It is sometimes deficient: accord- ing to Meckel, in the proportion of once in three times. In my own dissections I have always found it, though under various cir- cumstances of size and form. It is more flattened than the pre- ceding, and never so long. Sometimes it is double. Like the preceding, it has a great many filaments attached to, or emanating from it. The external filaments, amounting to about three in number, pass from it to the anterior fasciculi of the fourth, fifth and sixth cervi- cal nerves, between the origins of the scaleni muscles. Some of its filaments accompany the inferior thyroid artery, and, along with the superficial cardiac, form #a plexus around it, which reaches to the thyroid gland. The Middle Cardiac Nerve is formed by several of the anterior branches, collecting into a single chord. The latter descends along the external side of the primitive carotid, crosses, on the right side of the body, the root of the subclavian artery, and then going along the posterior face of the arteria innominata, it gets between the, aorta and the bifurcation of the trachea, where it is merged in the commencement of the cardiac plexus of nerves. On the left side, the middle cardiac nerve is formed by an assemblage of filaments from the middle and inferior cervical ganglions, which descend along the left subclavian artery to the aorta, and are joined, on the front of the latter, by the superficial cardiac nerve. On both sides, these cardiac nerves form intricate anastomoses with the pneumogastric nerve and its recurrent branch. 3. The Inferior Cervical Ganglion, situated as mentioned, near the head of the first rib, like the others, is subject to variations in its form and size. Several filaments may be traced between it and THE SYMPATHETIC NERVE. 499 the middle cervical ganglion. One penetrates into the canal of the transverse processes along with the vertebral artery, and, forming a plexus around it, may be traced distributing branches to the heads of the contiguous muscles, as high up as the second cervi- cal vertebra. The external branches of the inferior cervical ganglion are nu- merous and small. Some of them anastomose with the anterior fasciculi of the two or three inferior cervical and the first dorsal nerve. Others form a plexus around the subclavian artery, and follow the latter in its distribution, to the upper extremity and to the shoulder. The anterior branches of this ganglion concur, after some anas- tomoses with each other, to form a single chord, the Inferior Car- diac Nefve, which goes, on the right side, along the arteria inno- minata, to be blended with the cardiac plexus. On the left side, it is not so distinct, but is blended with the middle cardiac nerve, and forms its inferior root. Of the Cardiac Plexus of the Sympathetic. The Cardiac Plexus (Plexus cardiacus) is situated between the arch of the aorta, and the lower part of the trachea and the bron- chia, and extends from the division of the pulmonary artery to the commencement of the arteria innominata. It is formed, almost wholly, from the branches sent by the three cervical ganglions of the sympathetic of each side, and principally from that of the middle one, or the middle cardiac nerve. The filaments which come from the recurrent nerve and the par vagum are blended into the cardiac plexus in such a manner that they cannot be traced separately to the heart. It is worthy of remark, that the three cardiac nerves of the right side are more constantly found than the same number on the left, in consequence of the lower one of the latter soon merging itself, after its origin into the middle car- diac nerve of that side. The cardiac plexus is formed by the common assemblage of the nerves from the two sides of the neck, and is therefore single. From this plexus arise all the nerves which go to the heart, so that in tracing them the distinction between right and left is confounded. Scarpa has pointed out, in this circumstance, an analogy between them and the nerves which supply the abdominal viscera. 300 NERVOUS SYSTEM. The cardiac plexus is distinguished by the softness of its texture. For the purpose of description, its branches may be divided into Anterior, Posterior, and Inferior. The Anterior Branches are but few. They are found on the front of the arch of the aorta. One of them crosses it on the right side of the arteria innominata; others cross it from the foot of the left carotid and subclavian, downwards. In both cases, several of the terminating filaments run into the anterior coronary plexus.* The Posterior Branches are more numerous; but run only a short course, when they are merged in the anterior pulmonary plexus formed by the par vagum. The Inferior Branches are the largest and the most abundant. Some of them follow the pulmonary artery until its entrance into the lungs, others are distributed upon the pulmonary veins; but the greater number of them are arranged into two plexuses called Coronary, from their observing the course of the coronary arte- ries. The posterior coronary plexus is larger than the other. It reaches the base of the heart, along the pulmonary artery, and has its filaments distributed principally to the left auricle and left ven- tricle, observing the course of the left coronary artery and of its branches. The anterior coronary plexus gets in front of the heart, between the aorta and the pulmonary artery. It anastomoses freely at its superior part with the other, and is then distributed to the right auricle and ventricle, along the course of the right coro- nary artery and of its branches. Of the Thoracic Ganglions of the Sympathetic. These ganglions are twelve in number, and are placed on or near the heads of the ribs, at the commencement of each inter- costal space, and are only covered by the pleura. Their shape is irregular, and they differ also in size, being always smaller than the cervical ganglions. The chord of the sympathetic is continued, successively, from one ganglion to another, so that they form a complete chain by their connexion. * Scarpa. THE- SYMPATHETIC NERVE- 501 From each ganglion there proceeds one or more external branches, which go outwards to anastomose with the intercostal nerve of the corresponding part. Each ganglion also detaches one or more internal branches or filaments to the adjacent parts lying on the vertebral column: some go to the cellular substance, others to the longus colli muscle, others to the aorta, others to the cardiac and to the pulmonary plexuses. Among these internal branches there are several which concur to form the Splanchnic Nerves, of which there are two; the Great and the Small. The Great Splanchnic Nerve arises, by filaments, from the sixth to the ninth or tenth thoracic ganglions, inclusively; one or more filaments coming from each ganglion. They are directed down- wards and forwards on the sides of the dorsal vertebrae, covered by the pleura, and unite, successively, into a trunk about the eleventh dorsal vertebra. This trunk penetrates into the cavity of the abdomen, between the middle andthe internal part of the lesser muscle of the diaphragm, or by the opening for the aorta. Having got into the abdomen, the great splanchnic divides into several fasciculi, which, diverging from each other, are concealed on the right side by the liver, and on the left by the stomach. On each side of the aorta there is a large ganglion formed by an assemblage of several smaller ones: it is called the Semi-lunar. In it terminate, for the most part, these fasciculi: some of them, however, go immediately into the solar plexus, which emanates from the semi-lunar ganglion. The Small Splanchnic Nerve is. derived, by filaments, from the tenth and the eleventh thoracic ganglion, Having united, they penetrate the crus of the diaphragm, and, reaching the abdomen, the trunk is divided into two branches, of which the uppermost ascends to join the great splanchnic before its division, and the lower descends to join the renal plexus. Posterior Renal Nerves.—Besides these two splanchnic nerves, it frequently happens that there are others which come from the eleventh and twelfth thoracic ganglions, and from the communi- cating branch between the last thoracic and the first lumbar. They unite into a trunk which goes to the renal plexus, and have been called, by Walter, the Posterior Renal Nerves. 43* 502 NERVOUS SYSTEM. Of the Solar Plexus. The Semi-lunar Ganglion, situated, as mentioned, on the side of the aorta, is somewhat semicircular or oval, and is about an inch long; its form, however, is much diversified in different subjects. The several ganglions of which it is composed, are frequently fused into a single one. That of the right side is more voluminous than the other, and is placed between the ascending vena cava and the crus of the diaphragm, somewhat above the right renal artery. That of the left is situated upon the left crus of the dia- phragm, somewhat below the splenic artery. Between their inferior extremities, there are generally two or three smaller ganglions. These several ganglions are united by numerous filaments, which send out many ramifications, and anastomose freely with each other. The preceding arrangement may be considered as the root of the Solar Plexus, which extends from the cceliac artery to the lower margin of the emulgents, and as it is common to the gang- lions of the two sides, it is an inch and a half or two inches wide. Bichat has very properly remarked, that this plexus seems to exist for the aorta, as all the divisions which it sends out follow so ex- actly the branches of this artery, that we are forced to adopt the latter as the basis of the description. The intertexture and the number of the branches emanating from the solar plexus are so complicated, that a description of individual branches would be almost endless, as well as unintelligible; anatomists are> therefore, generally agreed to describe the plexus according to the order of the arteries which its detachments adhere to and surround. 1. The Diaphragmatic Plexus consists of a few filaments coming from the superior part of the solar, and following the course of the phrenic arteries. Some of them anastomose with the terminating filaments of the phrenic nerve, in the thickness of the diaphragm. 2. The Plexus which surrounds the Cceliac Artery, like it, is quickly disposed into three divisions, which follow the, branches of this artery. a. The Superior Coronary Plexus of the stomach, is the small- THE SYMPATHETIC NERVE. 5Q3 est of the three. It attends the corresponding artery along the lesser curvature of the stomach to the pylorus, supplying the sto- mach continually with very fine filaments. In its course, it anas- tomoses with the par vagum, and sends filaments to the hepatic plexus. b. The Hepatic Plexus is the largest of the three. It surrounds the hepatic artery and the vena portarum, and, in its course, de- taches branches which go with the right gastro-epiploic artery to the great curvature of the stomach, and constitute the inferior coronary plexus. Branches are also sent to the pancreas and to the duodenum. The hepatic plexus then enters the transverse fissure of the liver, and its branches may be traced to the several lobes and to the gall-bladder. c. The Splenic Plexus is but small, and surrounds the splenic artery. The few branches of which it is composed, anastomose but rarely with each other. Some of them are distributed upon the pancreas, along with the pancreatic branches of the splenic artery; others go with the left gastro-epiploic artery to the left extremity and the greater curvature of the stomach; the remain- der penetrate into the substance of the splden, through its fissure, along with the branches of the splenic artery. 3. The Superior Mesenteric Plexus is derived from the solar, near the superior mesenteric artery; it descends some short dis- tance on the aorta, before it reaches the latter. It passes with the artery between the pancreas and the duodenum, and is then in- cluded between the two laminae of mesentery: it is then distributed, by very numerous filaments, along with the branches of the artery, to the whole of the small intestines, to the ccecum, and to the ascending and transverse colon. 4. The Renal Plexus, one on each side, is derived from the lower lateral part of the solar, and from the Posterior Renal Nerves. Two or three ganglions, on the root of the renal artery, contribute to it, and it is also re-enforced by an addition from the lesser splanchnic nerve. The branches which form this plexus do not anastomose much, till they get near the kidney ; they then penetrate into its substance, through the fissure. Some filaments 5Q4 NERVOUS SYSTEM. from this plexus go to the capsula renalis: others follow the course of the spermatic artery, and constitute the spermatic plexus which goes to the testicle in the male, and to the ovarium in the female. 5. The Inferior Mesenteric Plexus is a continuation of the solar, on the anterior face of the abdominal aorta. It is much smaller than the superior mesenteric plexus, though it receives continually, in its descent, filaments from the lumbar ganglions of the sympa- thetic. It forms frequent anastomoses around the root of the infe- rior mesenteric artery, and near the superior strait of the pelvis, is resolved into two columns of fibres. One column is distributed along with the artery to the rectum, to the sigmoid flexure of the colon, and to the left section of the latter, thereby anastomosing with the colic branches of the superior mesenteric plexus. The other column descends into the^pelvis,.in front of the sacrum, and contributes to form the hypogastric plexus, but several of its branches also follow the external and the internal iliac arteries. Of the Lumbar Ganglions of the Sympathetic. These ganglions are five in number, on either side, and are placed anteriorly on the sides of the bodies of the lumbar verte- brae, near the anterior margin of the psoas magnus muscle. Their form is irregular; they are smaller than the cervical ganglions, but larger than the dorsal. The last thoracic ganglion is united to the first lumbar by a small branch, which may be considered as the continuation of the sympathetic. A deficiency of this branch has, however, been several times observed by anatomists; also a deficiency in the connecting nervous chord of the ganglions below. The ganglions themselves are inconstant in their number, being sometimes less than five; they vary likewise in their situation. It is to be under- stood, however, that in a majority of subjects, the sympathetic goes on uninterruptedly from one ganglion to another, sometimes by one branch; on other occasions, by two or three. Each lumbar ganglion sends outwards one or more external branches, which applying themselves to the body of the contiguous vertebra, reach the corresponding intervertebral foramen of the loins, and join with the anterior branch of the corresponding luni- THE SYMPATHETIC NERVE. 505 bar nerve. Some of these external branches are spent upon the quadratus lumborum muscle. Each lumbar ganglion, or the intermediate chord of the sympa- thetic, also detaches branches internally, which are very small, and more or less interwoven with each other. These branches get to the abdominal aorta, and, joining the inferior mesenteric plexus upon it, are distributed along with the latter. Of the Sacral Ganglions of the Sympathetic. There are generally three of these ganglions which may be readily found: sometimes four or five. They are situated in a line, on the anterior face of the sacrum, near the corresponding foramina for the transmission of the sacral nerves; and are united with each other by intermediate fibres, from one to three in num- ber, which are the continuation of the sympathetic nerve. Bichat asserts, that frequently the first of these ganglions is not united to the last of the lumbar by an intermediate nerve, so that there the continuity of the sympathetic is interrupted. Each ganglion sends off, externally, one or more filaments, by which it is united to the corresponding sacral nerve: it also de- taches filaments in this direction to the pyriformis and the levator ani muscles. Each ganglion likewise detaches, from its internal margin, ramifications, which go obliquely downwards on the front of the sacrum, and anastomose with corresponding filaments from the op- posite side. From these ganglions many branches pass forwards to the hypo- gastric plexus; which is formed by them, by the inferior mesen* teric plexus, and by a great many filaments from the lower sacral nerves, principally the third. The plexus is distributed upon the rectum, the bladder, vesiculae seminales, and prostate of the male; and, in place of the two latter in the female, upon the vagina and the uterus. The last sacral ganglion detaches downwards one or more fila- ments, which lie upon the front of the os coccygis, and anastomose with the corresponding filaments from the other side, to form a sort of arch, the convexity of which is downwards. In this man- ner, terminates the chord of the sympathetic nerve. 506 NERVOUS SYSTEM. CHAPTER III. Of the Nerves of the Medulla Spinalis, The nerves of the medulla spinalis, with the exception of the first, which, from its position, is generally called the Sub-occipital by anatomists, are arranged into cervical, dorsal, lumbar, and sacral, according to the order of the intervertebral foramina, through which they pass out: but a much better division would be Cervical,* Thoracic, and Abdominal. Their mode of origin, and the ganglions formed by them, have been pointed out in the ac- count of the medulla spinalis. SECT. I.—OF THE UPPER NINE SPINAL NERVES. These are spent upon the neck, upon the upper extremities, and upon the diaphragm. They consist in the Sub-occipital Nerve, the Cervical, and the First Dorsal. Of the Sub-occipital Nerve. The Sub-occipital Nerve (Nervus Infra-occipitalis, decimus cerebri) is one of the smallest that proceeds from the medulla spi- nalis. It has the peculiarity, generally, of arising by a single root, which comes from the anterior chord of the medulla spinalis, between the occiput and the first cervical vertebra. This root consists of from two to six or seven fasciculi, situated one above another. When the posterior root exists, it is very small, is com- posed of from one to three fasciculi, and anastomoses with the accessory nerve. The trunk of this nerve passes from the vertebral cavity through the foramen formed in the dura mater by tbe vertebral artery; it goes out below the latter, and between the occiput and the first * In this case, the term Cervical would include the first eight. upper nine spinal nerves. 507 vertebra, behind its superior oblique process. It there forms a small long ganglion, like the other spinal nerves, and then divides into an anterior and a posterior fasciculus. The anterior fasciculus is the smaller of the two; it follows, in some measure, the course of the vertebral artery, and going for- wards to the front of the transverse process, is then divided into several fine filaments, some of which go to the contiguous mus- cles on the frorlt of the vertebrae; others join themselves to the pneumogastric and hypoglossal nerves, and to the superior cervi- cal ganglion of the sympathetic; others anastomose with the first cervical nerve. The posterior fasciculus runs backwards, and is distributed to the recti and the obliqui muscles on the back of the neck, and to the complexus. Of the Cervical Arerves. These are seven in number: the first one gets from the spinal cavity between the atlas and the dentata, and the last between the seventh cervical and the first dorsal vertebra. After the ganglion is formed upon the posterior fasciculus of each, the trunk, made by the union of the two fasciculi, divides almost immediately again into an anterior and a posterior trunk. Of the First Cervical Nerve. The posterior trunk is the largest, and goes directly backwards. It has its filaments distributed to many of the muscles on the upper posterior part of the cervical vertebra, and to the integuments of the part. Some of the branches ascend through ihe muscles, near the occiput; and, rising up on the latter, are distributed upon its integuments, and upon the occipito-frontalis muscle. The anterior trunk is directed forwards under the inferior ob- lique muscle of the neck, and then divides into two branches: the superior joins the anterior branch of the sub-occipital nerve, and anastomoses with the first cervical ganglion of the sympathetic, and with the par vagum and the hypo-glossal nerve; the inferior joins the anterior branch of the second cervical nerve. 508 NERVOUS SYSTEM. Of the Second Cervical Nerve. This nerve issues between the second and the third cervical ver- tebra. Its posterior trunk is spent upon the trapezius, complexus, and other muscles on the back of the neck, and upon the integu- ments of the latter; it also anastomoses with the posterior trunk of the nerve above and below. The anterior branch or trunk detaches, first of all, some small filaments to the muscles on the front of the cervical vertebrae; it then divides into two principal fasciculi, one of which ascends and the other descends. The ascending branch goes upwards and backwards, and early in its course anastomoses with the first cervical nerve, thereby forming with it a nervous noose; it then mounts upon the occiput, and is distributed upon the parts on the latter region, anterior to the occipital branches of the preceding nerve. The descending branch turns over the posterior margin of the sterno-cleido mastoideus muscle, and gives filaments to it. It is distributed afterwards by branches, some of which go to the inte- guments of the middle and inferior parts of the neck, (nervi subcu- tanei colli medii et inferiores,) others go the integuments of the neck upon the angle and the base of the lower jaw, (nervi subcu- tanei superiores,) and one to the external ear,, (nervus auricularis cervicalis.) From the anterior fasciculus of the second cervical nerve, there proceeds a filament downwards, which is the upper root of the phrenic nerve; another filament from it joins the superior cervical ganglion of the sympathetic. Of the Third Cervical Nerve. This nerve comes out between the third and the fourth cervical vertebra. Its posterior fasciculus is distributed to the muscles on the back of the cervical vertebrae, and to the integuments of the part; anastomosing, by its branches, with the nerve above and below. The anterior fasciculus is larger than the posterior, and goes obliquely downwards and outwards at first; it sends anastomotic branches to the nerve above and below; it also anastomoses with UPPER NINE SPINAL NERVES. 509 the superior cervical ganglion of the sympathetic and with the de- scendens noni. One of its branches, being joined by the branch just spoken of, from the second cervical nerve, constitutes the root of the phrenic nerve. But the principal number of its branches are dis- tributed to the integuments along the clavicle, (nervi supra-clavi- culares,) the upper part of the sternum, and the shoulder; some of them going into the contiguous muscles, as the trapezius, subcla- vius, &c. Several anastomoses exist between the branches of this nerve and the terminating branches of the nervus accessories. The three preceding cervical nerves form, by their anastomoses with each other, a plexus, consisting in a number of large loops or arches, which lie upon the sides of the muscles connected with the transverse processes of the cervical vertebrae. There are com- monly two series of anastomoses: the branches of the first series, form the second series, and from the latter proceed, for the most part, the several branches which have been described. These anastomoses are covered by the upper half of the sterno cleido- mastoid muscle, are involved in the cellular membrane surround- ing the great vessels of the neck, and are covered by the lympha- tic glands. Their intertexture and distribution are such, that no adequate idea of them can be conveyed without dissection. From this plexus several branches go to the sterno-mastoid muscle, and it is united above to the sub-occipital nerve and below to the fourth cervical. Of the Phrenic Nerve* The Phrenic Nerve (Nervus Phrenicus, Diaphragmaticus) arises, in the manner stated above, from the anterior fasciculus of the second and of the third cervical, and is assisted generally by two or three filaments from the upper part of the brachial plexus. It descends, vertically, on the humeral side of the internal jugular vein, but removed a considerable distance from it, and is attached, by cellular substance, to the front of the scalenus anticus muscle. Getting, in its descent, to the internal margin of the latter, it passes into the thorax, at the inner margin of the first rib, between the subclavian artery and the subclavian vein, the latter being before it. It then goes along the superior mediastinum to the pericar- dium, to the side of which it adheres in front of the root of the Vol. II.—41 510 NERVOUS SYSTEM. lung, being between the pericardium and the corresponding por- tion of the pleura; it finally reaches the diaphragm, to which it is distributed. Just before the phrenic nerve reaches the diaphragm, it radiates into several branches, which interchange filaments. Some of the branches are distributed to the convex surface of the diaphragm; others penetrate this muscle, and are distributed in its thickness and upon its concave surface. On the right side some of these branches pass through the opening for the ascending vena cava, and, thus getting into the abdomen, anastomose with the solar plexus, and with the pneumogastric nerve. The phrenic nerve of the left side is nearer to the root of the lung than that of the right, in consequence of the projection of the apex of the heart on that side. Its distribution in other respects does not present any remarkable difference from the other; its branches radiate in the same way to the diaphragm, and supply its thickness, as well as its upper and under surfaces. It sends some filaments to the lower part of the oesophagus. The phrenic gives off in the neck a few filaments to the scalenus anticus, and the rectus anticus major muscle. It also communi- cates there, with filaments from the inferior cervical ganglion, and sometimes from the superior cervical. Of the Four Inferior Cervical Nerves. The trunks of these nerves, on issuing from the intervertebral foramina, have one general mode of distribution, which permits them to be described together or in common. The posterior branches are much smaller than those of the pre- ceding cervical nerves; they go backwards between the complexus and the transversalis colli, and leave filaments in their passage with them and other muscles: they then reach the splenius and the tra- pezius, to which and to the integuments of the neck they are dis- tributed. The anterior branches are large; they appear on the side of the neck, between the scalenus anticus and medius muscles ; sometimes perforating the substance of one or the other of these muscles. They each detach filaments to the sympathetic. The fourth, also, commonly sends one to the phrenic. They then form the Bra- chial Plexus. UPPER NINE SPINAL NERVES. 511 Of the Brachial Plexus and the Nerves of the Upper Extremity. The Brachial or the Axillary Plexus is formed by the junction and the intertexture of the four inferior cervical nerves, and the first dorsal or thoracic. It extends from the scaleni muscles to the axilla, on a level with the neck of the os humeri. The nerves at first converge, and are situated somewhat behind the subclavian artery where it passes over the first rib; but are at various heights above it according to their origin, with the exception of the first dorsal nerve, which has to ascend in order to pass out of the tho- rax. The plexus is formed in the following manner. The fourth and the fifth cervical nerves unite near the scaleni muscles into a sin- gle trunk, which runs a short distance downwards, and then splits into two. The seventh cervical and the first dorsal do the same. The sixth cervical is the central nerve of the plexus, and after going downwards two or three inches, it bifurcates also. Combi- nations of these primary divisions are formed, which are dissolved, and then reformed, in such a way that a complex intertexture of the original nerves takes place. This intertexture surrounds the axillary artery somewhat like the braids of a whip-cord, from the clavicle to the os humeri below its head. In this course the axil- lary plexus passes along with the artery between the subclavius muscle and the first rib, lies in contact with the superior part of the serratus major anticus muscle, and immediately below the articulation of the shoulder joint. The axillary vein is in front of it. The nerves which proceed from the axillary plexus are the Scapular; the Thoracic; the Axillary; the two Cutaneous; the Radial; the Ulnar; and the Median. They supply the superior extremity, including the shoulder and the axilla. 1. The Scapular Nerve (Nervus Scapularis, or Supra-Scapu- laris) is a small branch coming commonly from the upper part of the plexus, as formed by the fourth cervical nerve. It goes back- wards in company with the arteria dorsalis superior scapulae, through the notch or foramen of the upper costa of the scapula; and having thus got to the posterior face of the latter, it gives filaments to the supra spinatus muscle; continuing its course then 512. NERVOUS SYSTEM. on the posterior face of the cervix scapulae, it is lost in filaments upon the infra-spinatus and teres minor muscles. 2. The Subscapular Nerves (Nervi Subscapulars) of Bichat present some varieties in their origin ; occasionally they come from the same trunk, but commonly each has its peculiar root from the central parts of the axillary plexus. There are generally three of them. One of them descends behind the axillary vessels, be- tween the subscapularis and the serratus major anticus; it crosses the teres major, and is lost upon the contiguous part of the latissi- mus dorsi. Another is distributed upon the subscapularis muscle. The third descends along the anterior margin of the subscapularis for a short distance, and distributes filaments to it, to the teres minor and major muscles. 3. The Thoracic Nerves (Nervi Thoracici) are primarily two or three in number, and proceed from about the middle of the plexus. The fasciculi into which they are resolved, may be dis- tinguished as anterior and posterior. The former are distributed, by filaments, to the subclavian muscle, to the pectoralis minor and major, and to the integuments covering the latter. The posterior thoracic has its origin somewhat concealed by the scalenus anticus muscle. It descends into the axilla, adhering to the serratus major muscle for some distance, and is then distributed by many fila- ments to this muscle. 4. The Axillary Nerve (Nervus Axillaris, or Circumflexus,) comes from the inferior part of the plexus. Immediately after its origin, it goes downwards and outwards over the upper extremity of the subscapularis muscle. It then winds around the os humeri, between the teres minor and major muscles, observing the course of the posterior circumflex artery, and, finally, terminates on the under surface of the deltoid muscle. This nerve sometimes gives off the subscapular nerves, and, in- deed, it is usual for anatomists to include the description of the latter in it. As it turns around the bone, it divides into two prin- cipal trunks; the superior goes to the inferior margin of the infra- spinatus, and to the posterior margin of the deltoides; the inferior is distributed principally in the substance of the deltoid muscle, but some of its filaments, by perforating the latter, reach the skin, UPPER NINE SPINAL NERVES. 513 and constitute the nervus cutaneus humeri. Filaments go from the nervus axillaris, in the early part of its course, to the sub- scapularis and the two teres muscles. 5. The Internal Cutaneous Nerve (Nervus Cutaneus Internus*) arises from the lower part of the axillary plexus, and is one of the smallest of those which go to the arm. It is situated between the median and the ulnar nerve, and adheres almost as far as the elbow, to the basilic vein. In its descent, this nerve detaches several small filaments, which, perforating the fascia of the arm, are distributed to the integuments of the biceps muscle, and to those on the internal face of the triceps. Somewhat above the bend of the elbow, at the place where the median basilic vein joins the basilic, but occasionally some inches higher up, the internal cutaneous becomes superficial, and splits into two branches of nearly equal magnitude, which diverge but little from each other at first. The branch nearest the interna! condyle of the os humeri, lies in front of the basilic vein, as it passes over the elbow joint; and continues in this position for two or three inches: it goes down the front of the fore arm on its ulnar side, but inclines continually to the back of the fore arm. In this course, it detaches small ramifications to the integuments about the internal condyle, and about the heads of the flexor muscles; it also detaches continually, from its sides, small filaments to the in- teguments of the ulnar side of the fore arm both anteriorly and posteriorly, some of which reach to the hand. The other, being the anterior, or the external branch of the internal cutaneous, which is nearer, the radius, passes beneath the median basilic vein,- about six lines from the basilic; but, just before it does so, it de- taches a very superficial cutaneous filament, which crosses in front of the median basilic vein about its middle, and is lost a little be- low the bend of the arm. The anterior or outer branch of the. internal cutaneous having got from beneath the median basilic vein, goes superficially as far as the middle of the fore arm with- out sending off any filaments of note; it is then divided suc- cessively into several, which diverge to supply the skin down to the wrist. *• Antonius and Caldani, Tabul. CCLVIII. 44* 514 NERVOUS SYSTEM. 6. The Muculo-Cutaneous Nerve (Nervus Musculo-Cutaneus, or Cutaneus Externus,) is somewhat larger than the preceding, and arises from about the middle of the brachial plexus. It de- scends a short distance, and then perforates obliquely the upper part of the coraco-brachialis muscle. Having passed through this muscle, it continues its course obliquely, between the bra- chialis internus and the biceps flexor, and, finally, makes its ap- pearance superficially on the outer side of the tendon of the latter. In this course, it distributes filaments to the several muscles with which it is connected. It afterwards passes the elbow joint under the median cephalic vein near its middle, and descends between the skin and the fascia of the fore arm, near the outer margin of the median vein, to the hand: in this course, it is parallel with and on the front of the supinator radii longus. It distributes many filaments to the cor- responding integuments on the radial side of the fore arm, and, having at length got near the lower end of the radius, it divides into two orders of fibres, one of which is distributed to the integu- ments on the dorsal, and the other to those on the palmar side of the hand, about the root of the thumb. 7. The Radial Nerve (Nervus Radialis, or Musculo-Spiralis,) arises from the upper portion of the brachial plexus, but in such a way, that filaments from almost every part of the latter run into it. It is a large trunk which winds spirally around the os humeri, between the triceps muscle and the bone, by entering the fissure between the first and the third head of the triceps. It appears on the outside of the os humeri, between the brachialis internus and the triceps muscle; running for some inches in contact with their intermuscular ligament. While beneath the triceps, it sends seve- ral branches to its heads. There are three principal trunks after- wards from this nerve. a. The Ramus Superficialis Dorsalis is sent from it on a line with the point of the deltoid muscle. This branch then goes just below the skin, parallel with and over the external ridge of the os humeri; it, of course, crosses the origin of the muscles of the ex- ternal condyle. It continues superficial on the posterior external edge of the supinator radii longus muscle, and terminates in the integuments on the back of the hand. The continued trunk of the muscular spiral goes in the interstice NERVES OP THE UPPER EXTREMITY. 515 between the extensor muscles, and the brachialis internus, and, at the external condyle, divides into the other two branches, from which filaments proceed to the contiguous heads of the muscles. b. The Ramus Profundus Dorsalis perforates the supinator brevis muscle, getting beneath the radial extensors to the back of the fore arm; it is then distributed in numerous filaments to the muscles on the back of the fore arm, some of its* branches reach- ing to the wrist. c. The Ramus Superficialis Anterior seems to be a continuation of the main trunk of the nerve, and descending at the anterior margin of the supinator radii longus muscle, it joins with the radial artery and continues in its company to a short distance below the middle of the radius.* Here it crosses the bone obliquely beneath the tendon of the supinator longus, and then divides into a palmar and a dorsal ramuscle: the first being distributed to the muscles and integuments of the thumb, the second terminating so as to supply the back of the hand, of the thumb, fore, middle, and ring fingers to their extremities. 8. The Median Nerve {Nervus Medianus) descends the arm at the inner edge of the biceps muscle ; along the anterior surface of the brachial artery, adhering firmly to it, and the deep-seated veins, by cellular substance. As far as the elbow, it sends off no branch of importance. There it lies at the side of the biceps ten- don, crosses the lower part of the brachialis internus, and is be- neath the aponeurosis of the biceps. It then perforates the pronator teres and gets between the flexor sublimis digitorum, and the flexor longus pollicis, and enters the palm of the hand under the ligament of the wrist, at the radial edge of the tendons of the flexor sublimis. In the palm it is situated beneath the aponeurosis palmaris and the arcus sublimis of the arteries. The median nerve dispenses the following branches :—At the bend of the arm, it furnishes filaments to the heads of the first layer of muscles of the fore arm; and a little below, it detaches the Nervus Interosseus, which supplies filaments to the flexor longus pollicis and flexor profundus digitorum. The interosseous nerve then descends with the interosseous artery in front of the interos- seous ligament, and terminates in the pronator quadratus. * This position givps the whole nerve the name of radial. 516 NERVOUS SYSTEM. Before the median nerve reaches the wrist, it sends a branch which supplies with filaments the muscles and integuments of the ball of the thumb. In the palm of the hand, it divides and sub- divides so as to send a branch to each side of the thumb, of the fore, and of the middle finger, and to one side of the ring finger. These branches go along with the arteries to the ends of the fingers and thumb. 9. The Ulnar Nerve (Nervus Ulnaris) comes from the lowest section of the brachial plexus. It descends along the internal anterior part of the triceps muscle, in a groove formed between it, and the intermuscular ligament: it diverges, in this course, gra- dually from the median nerve till it reaches the elbow, when it is at its greatest point of separation. At the elbow, it is behind the internal condyle, in the groove between it and the olecranon, and separates the two heads of the flexor ulnaris muscle. It then gets to the fore arm between this muscle and the flexor profundus digi- torum, and continues between them to within two inches of the wrist joint, when it detaches the Ramus Dorsalis. The Ramus Dorsalis dips between the ulna and the tendon of the flexor ulnaris, runs along the internal margin of the ulna to the carpus; it then divides into ramuscles, which supply the ulnar side of the integuments on the back of. the hand, and on the backs of the last two fingers. At the interval behind, between the heads of the metacarpal bones of the middle and ring fingers, a considera- ble ramuscle joins one from the branch of the muscular spiral nerve which attended the radial artery. The Ulnar Nerve, having given off this dorsal branch, descends- along the radial margin of the tendon of the flexor ulnaris and the os pisiforme, above the annular ligament, to the palm of the hand. Getting beneath the aponeurosis, it there detaches first a deep- seated branch, which penetrates the muscles of the little finger to supply them, the interossei, and the. short flexor.of the thumb. The ulnar nerve then furnishes a. superficial branch, and after- wards divides into three; one for the ulnar side of the little finger, another for the opposing sides of the little and ring finger, and a third which joins the most internal digital branch of. the median.. nerve. THORACIC SPINAL NERVES. 517 SECT. II.---OF THE THORACIC SPINAL NERVES. The Dorsal or Thoracic Spinal Nerves (Nervi Thoracici, Dor- sales) consist in twelve pairs, the first pair goes through the inter- vertebral foramen, between the first and the second dorsal verte- bra, and the twelfth pair between the last dorsal and the first lumbar vertebra. The common trunk, formed after the ganglion of each nerve, goes but a short distance when it divides into an anterior and a posterior branch. The Posterior Branch (Ramus Dorsalis) of each nerve, goes backwards between the transverse processes of the corresponding vertebrae, and, having got beneath the multifidus spinae, is com- monly subdivided into internal and external ramuscles. The inter- nal are the smaller, and are distributed upon the muscles lying upon the spine, as the multifidus, the sacro-lumbalis, longissimus dorsi, and so on: their terminating filaments reach the skin. The exter- nal branches descend obliquely outwards beneath the longissimus dorsi, and then issue between the latter and the sacro-lumbalis, to both of which they dispense filaments: they afterwards are divided into branches, which go to the trapezius, latissimus dorsi, rhom- boideus, and to the corresponding integuments. The Anterior Branches of the Dorsal Nerves (Rami Subcostales) correspond with the intercostal spaces of the ribs. Each one, in a short course after its origin, applies itself to the rib-just above it, and accompanies the intercostal vessels in the groove, formed in the under margin of each rib. After it proceeds about one-half or two-thirds of the length of the rib, it separates gradually from it, and goes nearer the middle of the intercostal space and the supe- rior margin of the rib below. To the angle of the rib, each nerve is only covered in front by the pleura, but afterwards it goes be- tween the intercostal muscles. Near the sternum, the branches become superficial by escaping from between the intercostal mus- cles, and are distributed upon the pectoral muscles, and the adja- cent skin. These terminating branches of the five or six inferior dorsal nerves go to the upper portions of the abdominal muscles and their integuments. Not far from its origin, each dorsal nerve 518 NERVOUS SYSTEM. anastomoses with the ganglion or cord of the sympathetic, after the manner described in the account of the latter nerve.' There are some differences between the thoracic nerves in their manner of distribution. The anterior, fasciculus of the first, as mentioned, forms the lower part of the axillary plexus by joining itself to the seventh cervical. It sends out, however, a subcostal branch which goes along the inferior face of the first rib, supplying its intercostal muscles and having the general distribution alluded to. The Second Subcostal Branch, besides the common distribu- tion, detaches a fasciculus, which, penetrating between the ribs, gets into the axilla, and is augmented by a branch from the inter- nal cutaneous nerve of the upper extremity. It then descends along the internal posterior face of the arm to the elbow, and in this course detaches several fine filaments to the integuments. The Third Subcostal Branch in like manner detaches an axil- lary fasciculus which goes to the inferior part of the arm-pit, to the integuments of which, and to those on the internal face of the arm, it is distributed. It does not descend quite so low as the pre- ceding. These two nerves are called Intercosto-Humeral, and from their origin and course, are supposed to account for the numb- ness of the arm, in cases of angina pectoris. The Fourth, Fifth, Sixth, and Seventh Subcostal Branches of the Dorsal or Thoracic Nerves, about the middle of the ribs to which they respectively belong, are all divided into two branches. One of them, which is properly speaking the intercostal, continues in the intercostal space, giving filaments to its muscles and to the triangularis sterni; it then emerges near the sternum to terminate upon the great pectoral muscle, the mamma, and the integuments of the front of the thorax. The other branch is the external pectoral: it extricates itself earlier from the intercostal space, and is distributed upon the muscles and the integuments on the side of the thorax. * It is observed in pleuritis, that there is a deposite of lymph, mixed with the cellular adipose matter, surrounding the sympathetic, its costal branches, and the subcostal nerves until the latter get between the intercostal muscles.' This inflamed state must, no doubt, produce particular nervous phenomena ; as pain, difficulty of respiration, and derangement of the functions of the abdominal viscera. ABDOMINAL SPINAL NERVES. 519 The remaining subcostal branches, to the eleventh inclusively, have very much the same principle of distribution. Their inter- costal fasciculi, having reached the anterior ends of the intercostal spaces, pass on to the abdominal parietes, between the transversalis muscle and the internal oblique, to both of which they give fila- ments. They reach the external margin of the rectus abdominis muscle, and then divide into filaments, some of which go to this muscle, others pierce the fore part of its sheath and are ramified upon the integuments of the front of the abdomen. The Twelfth Subcostal Branch of the Dorsal Nerves, sends first a branch downwards, which joins with the first lumbar nerve. It then crosses in front of the quadratus lumborum muscle, to which it gives filaments as well as to the adjoining portion of the diaphragm. It afterwards divides into two branches, the superior of which goes for some distance between the two oblique muscles of the abdomen, detaching filaments to them, and finally terminates on the integu- ments of the abdomen: the other branch goes between the trans- versalis and the internal oblique, and is extended to the lower part of the rectus, and to the pyramidalis muscle, to all of which it distributes filaments. SECT. III.—OF THE ABDOMINAL SPINAL NERVES. There are five lumbar, and five sometimes six sacral nerves on each side; the first of them passes out of the intervertebral fora- men, between the first and the second lumbar vertebra; and the remaining lumbar and sacral nerves go, successively, through the foramina in the loins and in the sacrum. The anterior fasciculi of these nerves form a plexus which ex- tends from the upper part of the loins to the lower part of the sa- crum : it is designated under the general term of Plexus Cruralis. The posterior fasciculi are much smaller. Those of the loins go backwards between the transverse processes, and are distributed upon the sacro-lumbalis, the longissimus dorsi, the multifidus spinae, and the corresponding integuments. The posterior fasciculi of the sacral nerves are not so large, generally, as those of the lumbar: they get out through the foramina, on the posterior face of the sacrum, are distributed to the same muscles; to the origin of the 520 NERVOUS SYSTEM. glutaeus magnus, and to the integuments of the sacrum, and of the adjoining portion of the buttocks. The Plexus Cruralis, for the purpose of description, has been di- vided by anatomists into the Plexus Lumbalis, formed by the four superior lumbar nerves, and the Plexus Ischiadicus, formed by the last lumbar and the sacral nerves. The Lumbar Plexus (Plexus Lumbalis) is concealed by the psoas magnus muscle, and is placed between it, the lumbar verte- brae, and the quadratus lumborum : frequently the roots of the nerves forming this plexus penetrate through the substance of the psoas magnus, and form their unions in it. The plexus is narrow and pointed above, where it commences by the fasciculus of the last dorsal nerve joining the first lumbar; but it increases continually afterwards in breadth, owing to the nerves composing it, succes- sively anastomosing farther and farther from the spinal column. From this plexus proceed three principal trunks : the upper one the Anterior Crural (Cruralis Anterior) is of considerable size; and goes to the skin and the muscles on the front of the lower extre- mity ; the middle, called Obturator (Nervus Obturalorius,) is not so large as the preceding, and goes through the obturator foramen to the adductor muscles of the thigh ; the inferior formed by the whole of the fifth and a fascictflus from the fourth lumbar nerve, joins the upper part of the sciatic plexus in the pelvis. Besides these, there are several branches of smaller size and of less importance, pro- ceeding from the lumbar plexus. The Abdomino-Crural Branches, according to Bichat, are most commonly three in number, and come from the two upper lumbar nerves. The first of them goes obliquely downwards and out- wards, in front of the quadratus lumborum, to the posterior part of the spine of the ilium, and runs for a short distance along the crista of the bone: it gives filaments to the iliacus internus, and to the abdominal muscles, where they border upon this part of the bone. Some of the filaments become cutaneous, but the main trunk of the nerve reaches the anterior superior spinous process, by going between the transversalis and the internal oblique muscle; it then follows the inguinal arch to the external ring, through which it passes, and is distributed in filaments upon the groin, the pubes, and the scrotum. The second or middle branch arises from the plexus near the preceding; it descends along the external ABDOMINAL SPINAL NERVES. 521 margin of the psoas magnus, and crosses the iliacus internus, co- vered by the peritoneum; near the anterior superior spinous pro- cess, it gets between the lower margins of the abdominal muscles, and is distributed upon them there: some of its ramifications get also through the external ring, and may be traced to the scrotum. The third, or the inferior branch, arises from the plexus still lower down, and after having traversed the front of the iliacus internus, it emerges from the pelvis beneath Poupart's ligament, near the anterior superior spinous process; it then divides into filaments which penetrate to the skin through the femoral fascia, and are distributed along the external anterior face of the thigh. The Spermaticus Externus arises from the upper part of the plexus, by a fasciculus from the first lumbar nerve, which is in- creased by one from the second lumbar. It descends at first in the body of the psoas magnus muscle and then in front of it: it crosses the iliacus internus, somewhat above Poupart's Ligament, by directing its course towards the anterior superior spinous pro- cess of the ilium. Here, it involves itself in the edge of the abdo- minal muscles, and goes' on the posterior face of Poupart's Liga- ment; at the internal abdominal ring it joins the spermatic chord of the male, or the round ligament of the uterus of the female. In the first case, it is distributed to the spermatic chord and scrotum ; in the second, to the labium externum and mons veneris. The Cutaneus Externus arises from the lumbar plexus below the external spermatic. It passes across the iliacus internus to- wards the anterior superior spinous process, about an inch below the spermaticus externus, and crosses the latter nerve just at that process. Emerging from the abdomen, by penetrating the com- mencement of Poupart's Ligament, it is distributed in several branches to the integuments of the vastus externus muscle, and along the edge of the rectus femoris: one of the latter extends to the patella. The Cutaneus Medius is detached from the anterior crural, an inch or so above Poupart's Ligament. It arises among the cluster of branches, which come off there to be distributed to the iliacus internus muscle, and to the muscles of the thigh. It appears, superficially, on the thigh, for the first time, by penetrating the Vol. 11—45 522 NERVOUS SYSTEM. sartorius muscle, about the internal edge of the rectus femoris; it descends then along the same edge of the latter muscle, and is dis- tributed to its integuments. It does not descend so low as the external cutaneous. The Cutaneus Anterior arises, also, from the anterior crural nerve. It is on the inner side of the cutaneus medius, emerges from the fascia of the thigh, and crosses the sartorius muscle two or three inches below the cutaneus medius. It is distributed on the integuments of the vastus internus muscle, and some of its branches extend to the internal edge of the patella. The Cutaneus Internus arises from the anterior crural nerve, among the same cluster, above Poupart's Ligament. It divides into four or five branches of different lengths, and is distributed to the integuments of the adductor muscles, and along the inner front side of the thigh. One branch observes very much the course of the tendon of the adductor magnus, and reaches as far down as the inner side of the knee. The Anterior Crural (Cruralis Anterior) arises from the middle of the lumbar plexus: at first, it is beneath the psoas magnus mus- cle; it then gets to its outside, and passes from the abdomen, under Poupart's Ligament, about half an inch from the outside of the femoral artery. Before it reaches Poupart's Ligament, it gives off a cluster of nerves, several of which go to the iliacus internus muscle; others form the superficial or cutaneous nerves of the thigh just mentioned; and others, the deep-seated or muscular branches, which supply the adductor muscles of the thigh, its four extensors, the pectineus, the sartorius, and the gracilis. One of the branches of the anterior crural nerve is seen to ac- company the femoral artery, till the artery penetrates the adductor magnus; it then runs along the front margin of the tendon of the adductors in a iheca formed by this tendon and the origin of the vastus internus. The nerve alluded to is the Saphenus; it passes afterwards between the internal condyle of the os femoris and the sartorius muscle, attaches itself to the saphena vein, and is distri- buted to the integuments of the inner side of the leg, and of the upper internal parts of the foot. ABDOMINAL SPINAL NERVES. 523 The Obturator (Nervus Obturatorius) is derived from the mid- dle of the lumbar plexus, also; and has very much the same posi- tion, in regard to the psoas magnus, as the anterior crural nerve. It descends into the pelvis from beneath the psoas magnus, near the sacro-iliac articulation; and passes forwards and downwards to the obturator foramen ; having got through which, it divides into an anterior and a posterior branch. The first is distributed to the head of the adductor longus and brevis, and to the gracilis and integuments. The second terminates in the obturator exter- nus, and the adductor magnus. The Sciatic Plexus (Plexus Ischiadicus) is formed by the union of the last lumbar with the four upper sacral nerves; the last lum- bar, before it joins the plexus, receives the branch of the fourth lumbar nerve, which is left after the lumbar plexus is formed. This plexus is situated at the side of the rectum before the pyri- formis muscle. The volume of the posterior branches of the Sacral Nerves in- creases till the fourth; but the fifth and the sixth are much smaller, in fact only fibrillar. The anterior branches of the sacral nerves are much larger than the posterior. The first four communicate with the sacral ganglions of the great sympathetic, besides forming the sciatic plexus. They assist the sympathetic, to form the hypogastric plexus. The fifth, and the sixth when it exists, are distributed to the coccygeus, sphincter, and levator ani. The following small branches go from the Sciatic Plexus.* a. Nervi Glutaei: one passes through the upper part of the sciatic notch along with the artery, to the glutaeus medius and minimus; another below the pyriformis muscle to the glutaeus magnus. b. Nervus Pudendalis Longus Inferior, passes under the tuber * This is only given as the most frequent arrangement of the sciatic plexus, and of the branches of nerves which proceed from it; other arrangements will often be met with in the cavity of the pelvis, in which not so many sacral nerves are sent to the plexus ischiadicus, and the several branches proceeding from it depart in a difTe- rent manner. The small branches described sometimes come from a common trunk, called, in such case, the Small Sciatic. 524 NERVOUS SYSTEM. of the ischium to the glutaeus magnus; perineal muscles; urethra and integuments of the penis and scrotum in men; and to the infe- rior parts of the labium externum in women. c. Ramus Femoralis Cutaneus Posterior. This nerve is placed between the integuments of the thigh and the muscles which arise from the tuberosity of the ischium. It sends many branches, suc- cessively, to the skin on the back of the thigh; one of its branches, longer than the others, goes down to the ham, and there divides into several filaments, which are distributed to the integuments on the back of the leg. The Nervus Pudendalis Longus Superior comes from the third and fourth sacral. It goes in company with the internal pudic artery between the sacro-sciatic ligaments, and then divides into two branches; the inferior is distributed to the integuments and muscles of the perineum, to the urethra and scrotum; the superior passing along the ramus of the ischium and pubes with the trunk of the internal pudic artery, is distributed to the obturator internus, accelerator urinae, urethra, and afterwards, getting between the symphysis of the pubes and the penis, terminates on its integuments and the glans penis. The Nervus Ischiadicus, or the Great Sciatic, is the common trunk, formed from the sciatic plexus; it is much the largest nerve in the body, and passes from the pelvis between the pyriformis and the geminus superior. It crosses, vertically, the small rotator muscles of the thigh, being concealed by the inferior edge of the glutaeus magnus; it is there about half-way between the tuberosity of the ischium and the trochanter major. Thence it descends on the back of the adductor magnus, at the outer edge of the long head of the biceps flexor cruris. About half way down the thigh, sometimes a little lower, the Sciatic Nerve divides into the Popli- teal, or Posterior Tibial, and Peroneal. Occasionally this division takes place as high as the exit of the nerve from the pelvis; but in this case the fasciculi are parallel with each other as far as the middle of the thigh. From the trochanter minor to its usual place of division, this nerve is parallel with, and on the back of the thigh bone; afterwards the two branches begin to diverge. The popli- teal nerve continues straight downwards to the back and middle of the knee-joint, and to the interstice between the heads of the gas- ABDOMINAL SPINAL NERVES. 525 trocnemius muscle; whereas the peroneal nerve goes along the inner posterior edge of the biceps flexor cruris, and passes be- tween its tendinous insertion and the external head of the gastroc- nemius muscle. In this course, the following branches are sent from the sciatic.— Twigs to the little rotator muscles of the thigh.—The Cutaneus Internus Superior, which arises near the upper part of the thigh, and is distributed to the skin of the corresponding part.—The Cu- taneus Internus Inferior, which arises just below the last, and, descending upon the inner head of the gastrocnemius, is distributed to the integuments of the calf of the leg.—A large trunk, and sometimes, instead of it, distinct branches which go to the Adductor Magnus, Semi-membranosus, Biceps and Semi-tendinosus. The Peroneal Nerve (Nervus Peroneus) divides at the head of the fibula into two branches, the Peroneus Externus and the Tibialis Anterior; but, before this division, it sends a small branch to the external parts of the knee-joint, and two cutaneous branches called Peroneo-Cutaneous. The Internal Peroneo-Cutaneous de- scends behind the external head of the gastrocnemius, and, at the bottom of the leg, is united to a division of the posterior tibial called the External Saphenus, or Communicans Tibia?. The Ex- ternal Peroneo-Cutaneous is distributed to the skin, along the fibula. The External Peroneal Nerve (Peroneus Externus) gets between the head of the peroneus longus and the fibula, then between the peroneus longus and the extensor longus digitorum, leaving fila- ments to these several muscles as it goes along. It descends, at the outer edge of the last muscle, to the inferior third of the leg, giving out, in the mean time, many muscular branches. Here it penetrates the aponeurosis, and divides into cutaneous branches, which supply the lower part of the leg, and the upper surface of the foot and toes. This nerve is called, by the French, the Mus- culo-Cutaneous of the leg. The Anterior Tibial Nerve (Tibialis Anterior) gets obliquely between the fibula, the peroneus longus, and the extensor longus digitorum, to the front of the interosseous ligament, where it ac- companies the anterior tibial artery. It passes, with the artery, under the annular ligament of the ankle, and has its terminating 45* 526 NERVOUS SYSTEM. filaments going to the muscles and integuments of the upper sur- face of the foot, as far as the end of the -first two toes. One of its branches sinks down with the anterior tibial artery to the sole of the foot. High up in the leg it sends filaments to the knee-joint, and, in its course downwards, it furnishes the muscle on the front of the leg. The Posterior Tibial, or Popliteal Nerve, (Nervus Popliteus,) having the direction mentioned, is placed between the skin and the popliteal vein. It gets between the heads of the gastrocnemius muscle, and perforates the origin of the soleus; going with the posterior tibial artery, between this muscle and the flexor longus digitorum, to the bottom of the leg. It gives off the following branches: a. The External Saphenus, (Saphenus Externus, or Communi- cans Tibia,) which arises above the knee-joint, and, descending between the skin and the gastrocnemius, turns outwardly, and anastomoses with the cutaneous branch, alluded to, of the peroneal nerve. The common trunk, thus formed, passes behind the exter- nal ankle, along the external margin of the foot, and terminates on the outer toes, having given off a great number of cutaneous branches. b. Branches to tho heads of the gastrocnemius, soleus, plantaris, and popliteus. c. Branches to the flexor longus digitorum, tibialis posticus, and to the flexor longus pollicis pedis. d. A branch through the interosseous ligament, above, to the tibialis anticus. e. At the inferior part of the leg many cutaneous filaments, one of which gets to the sole of the foot. The Posterior Tibial Nerve, having given off these branches, divides, in the hollow of the os calcis, into the Internal and the External Plantar Nerve. The Internal Plantar (Plantaris Internus) proceeds along-side of the tendon of the flexor longus muscle of the great toe, and the flexor longus digitorum, and gives filaments to the contiguous muscles. It then divides in such a way as to furnish the two sides of the first three toes and the internal side of the fourth. ABDOMINAL SPINAL NERVE. 527 The External Plantar (Plantaris Externus) proceeds with the artery of the same name to the outer edge of the foot, between the flexor brevis digitorum and the flexor accessorius. It is distri- buted to the two sides of the little toe, and to the external side of the fourth toe. One branch penetrates to the interosseous muscles and to the transversalis pedis. A branch of considerable size is also detached, near the heel, to the muscles and integuments con- nected with the os calcis. THE END. INDEX TO VOL. II. Page Abdomen, generally, - . . . - - 12 General Situation of the Viscera of, - - - 14 Veins of, - - - - - - 285 Abdominal Aorta, Branches of, - - - - - 245 Absorbent Glands of the Abdomen, ... - 322 Head and Neck, - - - - 310 Lower Extremity, - - - 316 Upper Extremity, - - - 314 Thorax, .... 329 Parietes of Trunk, - - - 326 Absorbents of the Pelvis, - - - - - 316 Head and Neck, - - - -.312 Upper Extremities, and the Contiguous Parts of the Trunk of the Body, - - 312 Inferior Extremities, and the Contiguous Parts of the Trunk of the Body, - - 314 Organs of Digestion, - - - 318 Parietes of the Trunk, - - - - 326 Viscera of the Thorax, - - - 324 Absorbent System, Special Anatomy of, - - - - 310 General Anatomy of, - - - 301 Accelerator Urinae, - - - - - -115 Antrum Pylori, - - - - - - 31 Aorta, and the Branches from its Curvature, - - - 219 Aqueous Humour, ..---- 449 Aqueducts of Ear, - - ----- 466 Arachnoidea, ------- 365 Areola, - ------- 139 Arcus Sublimis, ----- 242 Q1Q Arteries, Texture of, - - - - ■ - 183 Arteria Aorta Thoracica, Branches of, - - - 243 530 INDEX. Page Arteria ad Cutem Abdominis, ----- 260 Alveolaris Superior, - - - - - 230 Anastdmotica, (Arm,) ----- 238 Anastomotica, (Thigh,) - 263 Articularis Superior Interna, Thigh, - - 263 Articularis Superior Externa, .... 264 Articularis Media, - - - - - 264 Axillaris, - - - - - . - 235 Articularis Inferior Externa, Thigh, - - 264 Articularis Inferior Interna, - - - - 264 Auricularis Posterior, ----- 227 Basilaris, ...... . 403 Brachialis, -.-... 237 Buccalis, ------- 230 Callosa, --. . ._ . 402 Carotis Primitiva, - - - - . - 221 Carotis Interna, ..... 222 Carotis Externa, ------ 222 Cavernosa Profunda Penis, - 258 Cceliaca, ------- 245 Cerebri Posterior, - 404 Cervicalis Posterior, ..... 233 Choroidea, - - - . . - 401 Ciliaris, ---..-. 427 Circumflexa Anterior of Axillaris, ... 237 Circumflexa Posterior, ..... 237 Circumflexa Externa, - - - - - 261 Circumflexa Interna, - - - - - 261 Circumflexa Ilii, ..... 259 Colica Sinistra Superior, - - - - - 249 Colica Sinistra Media, .... 249 Colica Sinistra Inferior, ..... 249 Communicans Posterior of Brain, - - - 401 Dentalis Inferior, --..-. 229 Dorsalis Carpi, ...... 240 Dorsalis Hallucis, ------ 267 Dorsalis Manus, - 242 Epigastrica, ...... 258 Facialis, ...... 224 Femoralis, -----.. 259 Frontalis, ...... 429 Gastrocnemia, -.-... 265 INDEX. 531 . Page Artena Gastrica, - - - - - - 245 Gastrica Dextra, --.... 246 Gastrica Sinistra, - - - ' . 247 Glutea, - - . . . . .255 Haemorrhoidea Inferior Externa, ... 257 Haemorrhoidea Media, - 254 Haemorrhoidea Superior Interna, - - - 249 Hepatica, ----... 246 Helicina, - - . . . -100 Iliaca Interna, ----.. 253 Iliaca Externa, - ----- 258 Ilio-Lumbaris, ------ 253 Innominata, ---... 220 Intercostalis Superior, ..... 232 Interossea Anterior, - - - - . 241 Interossea Posterior, - - - - - 241 Infra-Orbitalis, ------ 230 Inferior Cerebelli, ---.-. 403 Ischiadica, - - - - - - 256 Lachrymalis, --.--. 427 Lingualis, ...... 224 Magna Pollicis, ...... 240 Mammaria Externa, ----- 235 Mammaria Interna, - 233 Maxillaris Interna, - - - - - 228 Malleolaris Externa, ----- 266 Malleolaris Interna, ----- 266 Mesenterica Inferior, - 249 Mesenterica Superior, ----- 247 Metatarsea, .-..._ 267 Meningea Parva, ----- 229 Meningea Magna, ------ 229 Muscularis of Orbit, ----- 428 Nutritia, Brachialis, - 238 Nasalis, ------ 429 Obturatoria, ...... 254 Occipitalis, ------ 226 (Ethmoidea, - - - - - - 429 Palatina Superior, .... - 230 Palmaris Profunda, ----- 240 Palpebrals, ------ 429 Peronea, ------- 268 532 INDEX. Page Arteria Pedioea, - - ... 268 Perinea, ----... 257 Pharyngea Inferior, - 226 Pharyngea Superior, ----- 231 Plantaris Externa, ----- 269 ~* Plantaris Interna, - - - - - . 269 Poplitea, ------ 263 Profunda Femoris, ..... 26O Profunda Major Humeri, .... 237 Profunda Ninor, - - - - - 238 Pterygoidea, ------ 230 Pudica Interna, ----.. 256 Radialis, ...... 239 Radialis Indicis, -..-.. 240 Recurrens Radialis, ----- 239 Recurrens Ulnaris, - - - - - 241 Sacra Media, ------ 252 Scapularis, ----.. 236 Spheno-Palatina, - - - - - 231 Superior Scapula?, ------ 235 SuperBcialis Volae, - 239 Superior Cerebelli, ..... 403 Subclaviana, - - - - - -231 Splenica, - - - . ... 247 Tarsea, ------ 266 Temporalis, ...... 227 Thyroidea Inferior, ..... 232 Thyroidea Superior, - 223 Thoracica Longa, ..... 236 Thoracica Acromialis, ..... 236 Thoracica Axillaris, ----- 236 Transversalis Faciei, - 228 Temporalis Media, - 228 Temporalis Profunda, ..... 229 Thoracica Superior, ----- 235 Tibialis Anterior, ------ 265 Tibialis Postica, ----- 267 Tibialis Recurrens, ..... 266 Tympanica, ------ 229 Ulnaris, --.-... 240 Uterina, ...... 255 Vertebralis, - - - - - 232,402 INDEX. 533 Page Arteriae Bronchiales, ...... 243 Capsulares, ----.. 250 Emulgentes, ...... 250 Gastricse Breves, ...... 247 Gemellae, ...... 265 Intercostales Inferiores Aorticae, .... £44 Iliacae Priinitivae, ..... 252 Lumbares, - ---... 251 Mediastinals Posteriores, .... 244 CEsophageae, ...... 243 Pancreaticae Mediae et Sinistra, - - - 247 Phrenicse, >. 245 Profundae Perforantes Femoris, - - - 262 Pudendae Externae, - 260 Sacrae Laterales, ..... 253 Spermaticae, - - - - - - 250 Umbilicae <■ 297 Vesicales, - - - - - - - 256 Aryteno-Epiglottideus, ----- 147 Arytenoid Cartilages, - - - - - -143 Arytenoideus Obliquus, ..... 14Q Transversus, - - - - - 146 Arytenoid Glands, - - - - - -147 Auditory Nerve, ----... 468 Axillary Artery, Branches of, - - - - - 235 Bellini Ducts of, ..... t, 54 Biliary Ducts, - - - - - . -72 Bile, - -......73 Bladder, - - - - - . . -90 Structure of, - - - - . . 91 Bas-Fond of, - . . . . - 93 Blood, ------- 193 Analysis of, --.... 204 Coagulating Lymph of, or Fibrine, - - - 200 Red Globules of, - - - - - - 201 Serum of, ----- - 198 Blood Discs, - - - - - - -201 Bones of Tympanum, ..... 459 Brachial Artery, Branches of, - - - - - 237 Broad Ligaments of the Uterus, - - - - - 128 Brunner, Glands of, - * ' * • - 33 Vol.11.—46 534 INDEX. Page Brain, , - - 358 Membranes of, - - 359 Veins of, - - 404 Caruncula Myrtiformis, ... - 126 Cardiac Orifice, - 30 Carotids, Branches ofj . - 222 Capillaries, - 177 Capsule of Glisson, . - 20 Gaul, Situation of, - •15 Ccecum, - . - 44 Cerebellum, - . 373 Cerebrum, ... - 376 Chambers of Eye, - 450 Choroidea, . - 435 Chorda Tympani, - 469 Chylopoietic Viscera, - - 29 Viscera Assistant, * 64 Cilia, . - 416 Circulation of the Foetus, Peculiarities of, - - -Peculiarities of, connected with 292 its Nourishment, - 296 Conus Vasculosus, - 110 Circulatory System, - - 169 General Anatomy of, 169 Considerations on, - - 169 Special Anatomy of, • 207 Clitoris, - - - 121 Compressor Urethrae, - . 95 Coccygeus Muscle, . - 117 Cochlea, . 463 Colon, . - 45 Commissura Anterior, - . 390 Conjunctiva, . - 417 Corona Glandis, . 98 Cornea, - . - 433 Corpus, Callosum, . 382 Cavernosum, . - 99 Ciliare, . 436 Dentatum, . - 375 Fimbriatum, - - 109 Highmorianum, . - 131 INDEX. 535 Page Corpus, Spongiosum, .... 100 Spongiosum Vaginae, - 125 Corpora Striata, - - 381 Albicantia, .... - 379 Crura Cerebri, .... 379 Couper's Glands, .... - .105 Coronary Arteries, - 216-217 Veins, - - 217 Corpora Wolffiana, .... 89 Cremaster Muscle, .... - 112 Cricoid Cartilage, .... 142 Crico-Arytenoideus Posticus, - 146 Lateralis, - - - 146 Crico-Thyroideus, ..... - 142 Dartos Muscle, .... 107 Ductus Ejaculatorius, .... - 104 Choledocus, .... 73 Ducts of Bellini, ..... - 84 Ferrein, - 84 Ductus Galactophori, .... - 137 Dura Mater, ..... 359 Ductus Venosus, ..... - 296 . Arteriosus, .... 213-295 Duct of Liver, ..... - 69 Ductus Lactiferi, .... 137 Duodenum, ..... - 39 Dura Mater, ..... 359 Sinuses of, - - 362 Ductus Wirsungii, .... 79 Ear, ---.-... 451 Eminentiae Mammillares, ..... 379 Olivares, ...... 370 Endocardium, - - - - - - -215 Epididymis, - - - - - - -111 Epiglottis, - - - - - - - 143 Erector Clitoridis, - - - - - - - 122 Penis, - - - - - 114 Eustachian Valve, ----- 294-210 Tube, ------ 458 External Iliac Artery, Branches of, .... 258 536 INDEX. Page Eye>........415 Eyeball, - - - . . . - - 431 Eyelids, ------- 415 Fallopian Tubes, - - - . . . - 131 Foafcus, Peculiarities of, arising from want of Respiration, - 292 of Circulation connected with its Nourishment,- 296 Follicles of Lieberkuhn, ----- 54 Fornix,........383 Fossa Navicularis, - - . . . - 124, 102 Ovalis, - . 210 Fourchette, - . . . . . . J21 Fourth Ventricle, - * - . . . - 391 Fraenum Penis, ...... gg Frontal Nerve, - - . . . . * 475 Fundamental Portion of Cerebellum, -> 376 Ganglion Cavernous, --.... 495 Cervical, ---... 497 Lumbar, ---... 504 Lenticular, --.... 472 Spheno-Palatine, - - - - . - 414 Sacral, - , . . . - 505 Thoracic, -,.... 500 Gall Bladder, - - - - . . . 71 Glands, --......5 Glandulae Odoriferae Tysonii, ..... 98 Pacchioni, ...... 367 Palpebrarum, - - - - - 418 Glandula Pituitaria, ...... 380 Pinealis, ...... 386 Globus Major, - - - - - . - 111 Minor, - - - - - - - 111 Glands of Brunner, - - - - - - 38 Peyer, ------ 39 Gubernaculum Testis, 7 - - - - - 113 Head and Neck, Veins of, - - - - - 271 Heart, --.-.... 207 Right Auricle of, ----- 209 Right Ventricle of, - - - - - - 211 Left Auricle of, - - - - - - 213 INDEX Heart, Left Ventricle of, - Blood Vessels of, Texture of, - Hymen, Deo-Colic Valve, - fleum, - ... Infundibulum, Incus, - - . . Internal Uiac Artery, Branches of, - Inguinal Glands, Intestinal Canal, - Intestine, Small, Large, - Small, Situation of, - Large, Situation of, Iris, .... Isthmus of Vieussens, Jejunum, Kidneys, - Situation of, - Minute Structure of,. Labia, Interna, Externa, Labyrinth, ... Lachrymal Apparatus, Caruncle, - Ducts, - Gland, Nerve, ... Sac, Larynx, - - - - Lateral Ventricles, Lactiferous Glands, Levator Ani, - - - Lens, .... Lieberkuhn, - - - Ligamentum Ciliare, Denticulatum, 46* 538 INDEX. Page Ligamentum Palpebralc Internum, . - . - - 415 Externum, - . - . - 417 Ligamentum Suspensorium, - - . . -98 Liver,- ....... 64 Organization of, - - - . - - 66 Situation of, - . . . . 14 Lower Extremity, Veins of, - ... 283 Lobulus Spigelii, - - . . - 146 Epiglottideus, - - * 147 Hyoideus, ... - - 145 Thyroid Gland, - - 155 Cartilage, - - 142 Thoracic Aorta, Descending Branches of, - 243 Ducts, - - - - - - 3£9 Torcular Hierophili, - - - - - 363 Trachea, - - - - - - - 151 Transversus Perinei, (Male,) - 116 (Female, - - 125 Tricuspid Valve, - - - 212 Triangular Ligament of the Urethra, - - 118 Tubuli Seminiferi, . - - - - 109 Tuber Cinereum, . . - - - 379 Tubercula Quadrigemina, - 386 Tunica Albuginea, - - 109 Arachnoidea, - - - - - 365 Hyaloidea, - - - 427 Vaginalis, - - - - - 108 Vasculosa, - - - 109 Tympanum, - - - - - - 438 Tuberculum Loweri, - - 210 Umbilical Artery, - - - - - 297 Vein, - - - 296 Upper Extremity, Nerves of, - - 511 Veins of, - - - 280 Ureter, ..... • 87 Urethra, (Male,) - - - 101 (Female,) - - - - - 123 INDEX. 545 Page Urinary Organs, - - - . . . 81 Uterus, and its Appendages, - - - - - 126 Uvula Vesicae, ---... 92 Vagina, ---... ^ 124 Valve of Vieussens, - - - - . ,- 376 Valvulae Conniventes, - - - - . - 36 Valvula Thebesii, - - - - - - 211 Vasa Arteriarum, ------- 188 Capillaria, ...... \x 41: x ? jiaiw jo Aavaan ivnouvn inijiqiw jo Aavaan ivnouvn inoiqiw jo Aavaan ivn IONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAl LIBRARY OF ME I Ms \ TIONAL LIBRARY OF MEDICINE NATIONAl LIBRARY OF MEDICINE NATIONAl LIBRARY OF ME siaiw jo Aavaan ivnouvn iNoiaiw jo Aavaan ivnouvn inokmw jo Aavaan ivi TIONAl LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF ME |A/ I 3iojw jo Aavaan ivnouvn inoiqiw jo Aavaan ivnouvn j n i 3 i a j w jo Aavaan ivi TIONAl LIBRARY OF MEDICINE N A T I O N Al 11 B R A R Y O F M E D I C I N E NATIONi INAL LIBRARY OF MEDICINE NATIONAl LIBRARY OF MEDICINE NATIONAL LIBRARY OF ME VMbbbbbbbbI SwbbTI NATIONAL LIBRARY OF nlh Dioomq3 3 NLM010014433