9&W> IVNOIIVN 9NI3IQ1W JO Jk H V X fl I 1 IVNOIIVN 3NI3I03W JO A II V « 8 I 1 IVNOIIVN JNI3I01W JO 1 /Vl : ^ MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL II 5. ^S[n-*y ' 11 ;iK% -; nJ4. V ; IVNOIIVN 3NI3I03W JO A II V « 8 I 1 IVNOIIVN 9NDI01W JO A 9 V a 9 I 1 IVNOIIVN 3NI3I03W JO lVNOUVN 3NI3K13W JO UVaill IVNOIIVN 3NI3IQ3W JO AIIV » ■ I 1 IVNOIIVN 3NI3I03W JO fef^ix^i i m/ MEDICINE NATIONAL IIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL Lll ' f Medulla Spinalis, Sect. 1.—Of the First Nine Spinal Nerves, 2.—Of the Thoracic Spinal Nerves, ".—Of the Abdominal Spinal Nerves, Page Vol. II. 451 . 451 . 459 . 462 . 464 . 464 . 466 . 472 . 484 . 485 . 496 . 499 A TREATISE ON ANATOMY. BOOK I. FART I. On the General Anatomy of the Natural Skeleton, The skeleton is the bony frame work of the human body, and, by its hardness, is admirably suited to sustaining in its proper shape the whole fabric : to affording points for the attachment of muscles; and to protecting many of the viscera. Anatomists describe it as natural and as artificial; meaning by the first, the bones along with their natural connexions of ligaments, cartilages, and synovial membranes; and by the latter, the bones only, but kept together by artificial means. CHAPTER I. OF THE GENERAL ANATOMY OF THE BONES. SECT. I.—NUMBER, TEXTURE. The number of the bones is commonly the same in every middle aged adult, but they are less numerous then than in infancy, from several of them having been originally formed in pieces. The further fusion in advanced life, of contiguous bones into each other diminishes still more their number. Anatomists, however, are generally agreed to admit the following as distinct: voi. I.—A o SKELETON. For the Trunk—Twenty-four true or moveable vertebra', "a sacrum, four caudal vertebrae or bones of the coccyx, two innominata, twelve ribs on each side; a sternum, in three pieces, however, in the youthful adult: For the Head—An occipital bone, a frontal, a sphenoidal, an ethmoidal, two parietal; two temporal, each containing the small hones of the tympanum ; two superior maxillary, two palate, two malar or zygomatic, two nasal, two ungui- form or lachrymal bones, two inferior turbinated, a vomer and an inferior maxillary: One hyoiri, in three pieces, sometimes five in the adult, situ- ated in the throat : The remaining bones compose the limbs, and are therefore in pairs, or correspond exactly on the two sides of the body. They are, For the upper extremities—.the clavicle, the scapula, the humerus, the radius, the ulna, the eight bones of the carpus, the five bones of the metacarpus, the two phalanges of the thumb, the three phalanges of each of the fingers, the two, and some times more, sesamoid bones; For therlower extremities—The femur, the tibia, \he fibula, the patella, the seven bones of the tarsus, the five of the me- tatarsus, the two phalanges of the big toe, the three pha- langes of each of the smaller toes, and the two, sometimes more, sesamoids. There are, therefore, fifty-six bones to the trunk of the body; twenty-two to the head, not including those of the tym- panum; one insulated bone to the throat; sixty-eight to the two upper limbs; and sixty-four to the two lower limbs. In all two hundred and eleven. The redundancy or the defi- ciency of the sesamoid bones in a subject, may cause this number to be slightly increased or diminished. The situation of the bones varies ; some are profound, while others approach very near to the surface of the body. They are cither symmetrical; that is, consist of two lateral portions precisely alike; or else in pairs, having a perfect correspondence with one another. The symmetrical TEXTURE OF BOXES. 3 bones are the frontal, the occipital, the sphenoidal, the eth- moidal, the vomer, the,inferior maxillary, the hyoid, the spinal, and the sternum f and are situated under the middle vertical line of the body. The pairs arc on the sides of the middle line, more or less removed from it. The long bones (ossa longa) are generally cylindrical or prismatic, and have their extremities enlarged for the pur- pose of articulating with adjoining bones. The broad bones (ossa lata,) have their shapes diversified by muscular connex- ion and by the forms of the viscera they contain. The thick bones (ossa crassa) are situated in the vertebral column, and in the hands and feet; and have their surfaces very irregular. The bones present, on their periphery, eminences and cavities, a proper knowledge of which, is of the greatest im- portance to the surgeon. The former are called apophyses or processes, and are extremely numerous and diversified ; they serve for the origin and insertion of muscles and for furnishing articular faces. The cavities are also numerous; some of them are superficial, and serve for articular sur- faces ; others for the origin of muscles; for the enlargement of other cavities, as that of the nose and ear; and for pur- poses which will be mentioned elsewhere. Near the centre of the bones a canal is found which passes in an oblique direction and transmits blood vessels to their interior. There are also, at the extremities of the long bones, at the different points of the thick ones, and near the margins of the flat ones, a great many large orifices, which principally transmit veins : in addition to which, a minute inspection of any bone whatever, will show its whole surface dotted with still smaller foramina, also for the purpose of transmitting blood vessels. The density of bones is always well marked, and exceeds much that of all other parts of the body. It is, however, variable in different bones, and in different places of the same bone, hence their substance has been divided into compact and cellular, of which the former is external and the latter internal. 4 5KFLET0N. Tlie Cellular Texture, or substance, grows from the inter- nal surface of the other, and is composed of fibres and small laminae, which pass in every direction, by crossing, uniting, and separating. The cells resulting from this arrangement present a great diversity of form, size, and completion. They are all filled with marrow, and communicate very freely with each other. The latter may be proved in the boiled bone, by the practicability of filling them all with quicksilver from any given point, and, indeed, by the injection of any matter suf- ficiently fluid to run. The communications between them are formed by deficiencies in their parietes after the same man- ner that the cells of sponge open into each other. This tis- sue does not exist in the earliest periods of ossification, when the bones are cartilaginous almost entirely, but develops it- self during the deposite of calcareous matter. The manner of its formation is imperfectly understood, and it is not completed, till the bones originally consisting of several pieces are consolidated into one. The Compact Texture is also formed of fibres and laminae, which, however, are so closely in contact with each, other that the intervals between them are merely microscopical in the greater part of their extent, they become, however, more and more distinct, and larger near the internal surface and at the extremities of the bone, until the compact tissue is Gra- dually blended with the cellular structure, or lost in it. Its fibres are directed longitudinally in the cylindrical bones, radiate from the centres of the flat ones, and are blended so as to render it impossible to trace them in the thick ones. This disposition in the flat bones is much better seen in early life; subsequently it becomes indistinct. The compact tissue, particularly in the cylindrical bones, has in it a multitude of longitudinal canals, visible to the microscope, and some of them to the naked eye, which contain vessels and medullary matter. Those canals described by Havers, are, according to the estimate of Mr. Beclard, about one-twentieth of a line in diameter, on an average; they are, however, generally larger near the interior than the exterior surface of the bones, TEXTURE OF BONES. 5 and have frequent lateral communications with the spongy tissue, and with the external surface. The compact and the cellular tissues present themselves under different circumstances in the three species of bones. The compact has an unusual thickness in the bodies or dia- physes of the long bones, and is accumulated in quantities par- ticularly great in their middle, which, from its position, is more exposed than the extremities, to fracture from falls, blows, and violent muscular efforts. But as this texture approaches the extremities of the bones it is reduced to a very thin lami- na, merely sufficient to enclose the cellular structure and to furnish a smooth articular face for the joints. The cellular tissue, on the contrary, in the long bones is most abundant in their extremities, constituting their bulk there, and least so in their bodies. It is so scattered at the latter place as to leave a cylindrical canal almost uninterrupted in their middle for some inches. This canal, cellular in its periphery, has its more interior parts traversed in every direction by an extremely delicate filamentous tissue, which, from the fineness of its threads and the wide intervals between them, has been, not inaptly, compared to the meshes of a net, and is therefore spoken of specially under the name of the reticulated tissue of the bones, in contradistinction to the cellular. It is formed on the same principle with the latter, and though the term, from that circumstance, has been rejected, upon high authority, as superfluous, it appears worthy of retention, as it expresses a fact of some importance. Too weak to contribute in an appreciable degree to the strength of the bone, the reticulated tissue seems principally useful in supporting the marrow and in giving attachment to its membrane. The extremities of this canal gradually dis appear by becoming more and more spongy. In the Flat Bones, the compact tissue forms only their sur- face or periphery, and is of inconsiderable but generally uni form thickness; the space within is filled up with the cellular tissue, which is rather more laminated than it is in the long bones. G SKELF/l ON. In the Thick or Round bones, the. compact tissue forms their periphery also, but generally it is thinner than in the last; their interior is likewise filled up by the cellular tissue, and does not present differences of any importance from the ends of the long bones. A simple experiment on any of the cylindrical bones will prove that the tumefaction of their extremities does not add proportionately to their weight, as one inch or any other given section of the compact part weighs the same with a section of equal length from the cellular extremities. The swelling at the ends of the bones adds much to the safety of their articular union, as the extent of the surfaces is thereby much increased, and consequently they are less liable to dis- placement. The cylindrical and the cellular cavities, thus formed in the long bones, by increasing the volume of the latter, add greatly to their strength. Dr. Physick demon- strates this most satisfactorily by a scroll of paper, which on being rolled up successively, into cylinders of various sizes, has its power of sustaining lateral pressure, like a lever on one of its extremities, continually increased as its volume or diameter is augmented, until the latter reaches a certain point. The same highly distinguished teacher has also pointed out another very important advantage of the cellular structure. It is that of serving to diminish, and in many cases to prevent concussion of the brain, and of the other vis- cera, in falls and in blows. The opinion is verified by his demonstrating the momentum which is communicated through a series of five ivory balls suspended by threads, when one of them is withdrawn from the others and allowed to impel them by its fall. The momentum is so completely transmit- ted through the series, that the ball at its farthest end is impelled almost to the distance from which the first one fell. This familiar experiment, used as a preliminary test to the accuracy of his views, is immediately succeeded by his substituting for the middle one of ivory, a ball made of the cellular structure of bone. The same degree of impulsion now communicated at one end of the series, is almost lost in the meanderings of the cellular structure of the substitute COMPOSITION OF BONES. 7 particularly if the latter be previously filled with tallow or well soaked in water, so as to bring it to a condition of elas- ticity resembling the living state. SECT. II.—COMPOSITION OF BONES. The bones under every modification of shape and mechani- cal arrangement, are constituted by precisely the same ele- mentary matters, the principal of which are : an animal and an earthy substance, in intimate combination. Their mi- nute analysis, according to Berzelius, when they are deprived of water and of marrow-, affords 32 parts of gelatine, com- pletely soluble in water; 1 part of insoluble animal mat- ter; 51 parts phosphate of lime; 11 carbonate of lime; 2 fluate of lime; 1 phosphate of magnesia; 1 soda and muriate of soda. There are some other ingredients manifested in the analysis of Fourcroy and Vauquelin, as iron, manganese, silex, alumine, and phosphate of ammonia. The relative propor- tion of these ingredients is not uniformly the same, as the bones of the cranium and the petrous portion of the temporal, in a remarkable degree, have more calcareous matter in them, than the other bones of the same skeleton. There is also a considerable diversity in individuals according to their age and to certain morbid affections. The earthy matter gives to bones their hardness and want of flexibility, and is easily insulated from the other by com- bustion, which, in destroying the animal part, leaves the sa- line in a white friable state, but preserving the original form of the bone. If the heat be of a high degree, the calcareous part becomes vitrified, and its cells are blended by fusion. The action of the atmosphere long continued, also divests the bones of their animal matter, and the calcareous then falls into a powder. If the bones be kept beneath the surface of the ground, by which they are less affected by changes in temperature, the animal matter remains for an immense number of years. I have seen in the Hunterian Museum of London, preparations of the teeth of the Mastodon or 8 SKELETON. Mammoth, in which the animal matter was entire, notwith- standing the great lapse of years since it was in a living state. I am also informed by Mr. Say, a distinguished na- turalist, that animal matter has been detected in fossil shells, the existence of which was probably anterior to that of the human family. The phosphoric acid of bones gives them a luminous appearance at night. Bichat says, that in these cases he has found an oily exudation on the luminous points, probably from the marrow or contiguous soft parts. This phenomenon will account for many of the superstitions which in all ages have affected ignorant minds on the subject of burying grounds. The immersion of a bone in diluted muriatic acid is the best method of demonstrating the animal part in a separate state. The strong affinity of the acid for the earthy part and the soluble nature of the salt thus formed, leaves the animal matter insulated. In this state it preserves the ori- ginal form of the bone, is cartilaginous, flexible, and elastic. The action of hot water alone, upon a bone, by continued boiling, will, from the soluble nature of the cartilage, sepa- rate the latter from the earthy part, and convert it into gela- tine. The gelatine may be precipitated afterwards from the water by tannin. The mode of this combination of animal and of earthy matter is not understood, but it is generally supposed to exist by the extremely small cavities of the former receiving earthy particles after the same way that sponge holds water. There are no means for investigating the minute anatomy of the bones more favourable than the removal of the earthy part by an acid. The cartilage thus left is the complete mould, in every particular of form, into which the particles of calcareous matter were deposited. In this state the com- pact part of the bodies of the cylindrical bones may be sepa- rated into laminae, and these laminae, by the aid of a pin or fine pointed instrument, may be subdivided into fibres. The laminae, though enclosing one another, are not ex- actly concentric. I have observed, that the more super- ficial come off with great uniformity and ease in the adult COMPOSITION OF BONES. 9 bone, but their intertexture continually increases towards the centre. Bichat has objected to this demonstration of the bones, that the laminae are not formed in nature, but facti- tiously, by the art of the anatomist, and that their thickness depends entirely on the point at which one chooses to sepa- rate tlicin, they, therefore, may be made thick or thin at pleasure. It does not appear to me difficult to account for the manner in which this laminated arrangement is produced. The longitudinal fibres of the bones adhere with more strength to each other at their sides than they do to those above or below, in consequence of which a plane of thes6 fibres may be raised at any place and of any thickness. This fact does not involve the inference that the bones are formed by a suc- cessive deposite of one lamina over another, it merely incul- cates the mode of union between the fibres. I am, however, inclined to the opinion that the periosteum does secrete the external laminae in the adult bone, inasmuch as they separate with unusual facility from the subjacent one. We know that the periosteum has the power of this secretion, as a laminated deposite of bone on the roots of the adult teeth frequently met with, proves without doubt. The disposition of the cylindri- cal bones to separate into laminae, is also constantly mani- fested in such as are simply exposed to the atmosphere. The opinion of the laminated and fibrous arrangement of bones has been very generally adopted by anatomists. Mal- pighi, whose name is indis.solubly connected with minute investigations in anatomy, taught it. Gagliardi, also in ad- mitting it, thought he saw pins of different forms for holding the laminae together. Havers also saw the laminated and fibrous structure. In short, there are few of the older ana- tomists who have not given fully into the opinion. Among the moderns, the late Mr. Beclard, the distinguished and able professor of Anatomy in the school of Medicine in Paris, says, that when the earth is removed from bones by an acid, if they be softened by maceration in water, the compact sub- stance, which previously offered no apparent texture, is sepa- rated into laminae united by fibres ; the laminae themselves at a later period separate themselves into fibres; which by a VOL. I.—B 10 SKELEI ON. further continuation of the process swell, and become areolar and soft. A long bone examined after this process, divides in its body into several laminae, the most external of which envelops the rest, and the remainder by rarifying themselves towards the extremities are continuous writh the cellular structure there. J. F. Meckel, of the university of Halle, has furnished the following account in his General Anatomy of the Bones. " The fibres and the laminae which constitute the bones are not simply applied one against the other, so as to extend the whole length, breadth, or thickness of a bone, or to go from its centre to the circumference. They lean in so many dif- ferent ways one against another, and unite so frequently by transverse and oblique appendages or processes, that some^ great anatomists, deceived by this arrangement, have doubted the fibrous structure of bones. Nevertheless their opinion is not perfectly correct. In spite of those inflexions and anas- tomoses of fibres, the fibrous structure always remains very apparent, and one is warranted in saying, that the dimension of length exceeds the two others, in the texture of many bones. This predominance is chiefly well marked in the first periods of osteogeny, for at a later time, the fibres are so ap- plied against each other, as scarcely to be distinguished. But these longitudinal fibres never exist alone; there are many oblique or transverse ones from the first periods of os- sification, and they are even from the beginning so multiplied, that the number of longitudinal fibres does not prevail over them so much as at a subsequent period, when the fibres ap- proach nearer, in such way that the transverse become ob- lique, until at last, from the increase of the bone, the latter at first view, seems to be composed only of longitudinal fibres. The transverse and oblique fibres do not form a se- parate system; but continue uninterruptedly with the longi- tudinal, which they unite to each other."* The venerable Scarpa, about thirty years ago, advanced •Manuel D'Anat. Gen. Desc. et Path, traduit de L'AUemand par Jourda* etBreschet. Paris, 1825. * Jourdai* COMPOSITION OP BONES. 11 opinions adverse to the laminated and fibrous tissue of bones;* the latter doctrine he was induced to think a mere mistake arising from careless observation. Founding his own views upon what he had seen in the growing bone, in the adult bone when its earthy parts were removed by an acid, and upon certain cases of disease attended with inflammation of the bone; he denied without reservation the existence of laminae and fibres in bones, declaring that even the hardest of them were cellular or reticulated. It appears to me, in looking over his paper, that a desire to overthrow old doctrines and to establish new ones, has induced him to make one omission in the report of his experiments, otherwise unaccountable in a man of his general intelligence and candour. Having softened the cylindrical bones in an acid, he next proceeds to a long continued maceration of them, he finds, as other per- sons have done, the gelatine of the bone finally resolving itself into a soft cottony tissue. He has made but one jump from the immersion in the acid to the last stage of the pro- cess of maceration. Now, if in a short time after the bone had been softened in the acid, he had made an intermediate experiment, he would, no doubt, like all other inquirers, have found that the gelatinous part of the cylindrical bones was readily separable into laminae, and that by a pin or needle these laminae could be split into fibres, the greater part of which are longitudinal. Pounding the ends of these fibres with a hammer resolves them also into a very fine pe- lliculous structure. I have no objection to the conclusion that these laminae and fibres, as a final condition, produce a Tery fine microscopical cellular arrangement, which may be made more apparent in being distended by the development of gazeous substances, arising from putrefaction or macera- tion. Though I object most strongly to the assertion of there oeing no fibres in bones, when I have daily under my eyes pre- parations showing them; some of which demonstrate the fibres ■running principally longitudinally, others spirally, like the * A. Scarpa. De penitiori ossium structure commentarius. Lips. 1795. See also Anatomical Investigations, Philadelphia, 1824, by John D. God- man, M.D., for an English translation of the same. 12 SKELETON. grain of a twisted tree, and others having a mixed course. Upon the whole I think the description cited from Meckel exhibits this subject in a just and accurate manner. The more obvious arrangement of the cellular and com- pact tissue of the bones, indicates a considerable difference in their intimate texture; it is nevertheless similar, for one structure is converted alternately into another by disease, of which specimens abound in the Wistar Museum. In both cases, from the fibres are formed cells which exist every where, and are only larger and more distinct in what we call the cellular tissue ; but the compact part has also its cells, though they are smaller, more flattened, and for the most part microscopical. The Blood Vessels of the bones, though small, are very numerous. This is well established, by the success of fine injections, which in the young bone communicate a general tinge: and by scraping the periosteum from living bones, whereby their surface in a little time becomes covered with the blood effused from the ruptured vessels. In those ope- rations for exfoliation from the internal surfaces of the cylindrical bones, where it is necessary to excavate the bone extensively, in order to remove all the detached pieces, un- less the general circulation of the limb be previously arrested by the tourniquet, the cavity of the bone is flooded with blood. Bichat has also remarked, that the blood vessels of the bones become unusually turgid and congested in cases of drowning or strangulation. The Arteries which supply the bones, from their mode of distribution, are referred to three classes. The most nume rous and the smallest, are those which penetrate from the periosteum by the capillary pores found over the whole sur face of the bones. The next are those which penetrate the" larger foramina at the extremities of the long bones an7»t different points of the surface of others. And the third c ass called nourishing, amounts to but one artery for each of 7i cylindrical bones, which penetrates by an appropriate can,l" as mentioned, commonly near the centre of the bone COMPOSITION OF BONES. IS The arteries of the two first classes are generally extremely small. They ramify upon the compact and cellular struc- ture, penetrating it in every direction. At death they are commonly filled with blood, which renders the injection of them difficult. The third, or as commonly called, the nutri- tious artery, is of a magnitude proportioned to the bone to be supplied. Being single in every instance, it passes through the compact tissue, and having reached the medullary cavity, it divides immediately into two branches, each of which, in diverging from its fellow, goes towards its respective extre- mity of the bone. The latter ramify into countless capillary vessels upon the membrane containing the marrow, and finally terminate by free anastomosis with the extreme branches of the two other systems. The Veins of the bones are very abundant; they are uni- formly found in company with the branches of the third, or nutritious arteries, and then* common trunk goes out at the nutritious foramen into the general circulation. These rami- fications have been long known, and bring back the blood from the medullary membrane only. The veins which re- ceive the blood of the other arteries do not attend them, and were first of all found in the diploic structure of the cranium, which led to the discovery of them in all the other bones. The honour of the original observation has been claimed respectively by two very distinguished men of Paris, MM. Dupuytren* and Chaussier.f These veins issue from the bones by numerous openings distinct from those furnish- ing a passage to their arteries. This circumstance is re- markably well seen in the flat and thick bones, and at the extremities of the cylindrical ones. Having left the bone, they terminate after a short course in the common venous system. They arise exclusively from the spongy and compact struc- ture, by extremely fine arborescent branches, which, uniting successively, form trunks; these trunks penetrate the com- * Propositions sur quelques points d'Anatomie de Physiologic &c. Paris, 1803. f Exposition De la Structure de l'Enc^pbale. Paris, 1807. 14 SKELETON pact tissue, and escape from the bone by orifices uniformly smaller than the bony canals of which they are termina- tions. The canals are formed of compact substance, con- tinued from the external surface of the bone, and are lined by the contained veins. The parietes of the canals are penetrated by smaller veins entering into the larger. M. Dupuytren is of opinion, that only the internal membrane of the venous system exists in this set of veins, that it adheres closely to the bone so as to be incapable of exerting any action upon the blood ; that it is very thin, weak, trans- parent, and is thrown into numerous valves. Lymphatic vessels are generally seen only on the surface of the bones. Mr. Cruikshank, however, on one occasion, while injecting the intercostal lymphatics, passed his mer- cury into the absorbents of a vertebra, and afterwards saw them ramifying through its substance;* a fact which, along with what is known of the power of exfoliation in bones, proves sufficiently the existence of such vessels in them. Nerves have also been traced into them accompanying the nutritious arteries, f CHAPTER II. SECT. I.—OF THE PERIOSTEUM. The membrane which surrounds the bones is called peri- osteum, and is extended over their whole surface except- ing that covered by the articular cartilages. As this mem- brane approaches the extremities of the bones, it is blended with the ligaments uniting them to each other, from which • Anat. of Absorbing Vessels, p. 198. London, 1790. t Beclard, Elemens d'Anatomie Generate. Paris 1823 OF THE PERIOSTEUM. 15 the ancients adopted the opinion, that the ligaments and pe- riosteum were the same. Many fibres pass from the perios- teum to-the bone, by which it is caused to adhere. These fibres are more numerous and stronger at the extremities than in the middle of the cylindrical bones ; also, upon the thick bones, than upon the flat ones. The blood vessels of the bones accompany these fibres and contribute to the adhe- sion. The periosteum is united to the muscles and parts lying upon it by cellular substance. The adhesion of the periosteum to the bones varies in the several periods of life. In infancy it may be separated from them with great facility; in the adult it adheres more strongly in consequence of its internal face having taken on a secretion of bone, by which it is blended intimately into the bone it surrounds; and in old age it is still more adherent, from the progress of its ossification. It is thick and soft in the infant, and becomes thinner and more compact as life ad- vances. The organization of the periosteum is fibrous, and the fibres pass very much in the same direction with the fibres of the bones, excepting the flat bones, on which it is not radi- ated. Those fibres have different lengths, the more super- ficial are longer, while the more deeply seated extend but a small distance. Inflammation develops these in a striking manner, by occasionally making the membrane as thick as an aponeurotic expansion. The blood vessels of the periosteum are numerous, and can be easily injected. They come from the contiguous trunks, and ramify minutely, into a vascular net-work, many of whose branches penetrate into the bone, and have the distri- bution already mentioned. A few lymphatic vessels have been observed in it. Its nerves have not been clearly discovered, though the sensation of extreme pain, when violence is done to it in an inflamed state, may be thought a proof of their ex- istence. In health its sensations are null, or extremely ob- scure. The periosteum receives the insertion of tendons, of liga- ments, and of the aponeuroses. In early life, owing to the 16 SKELETON. slight attachment of this membrane to the bones, all these parts may be torn from them with but comparatively little force. Bichat* having advocated the opinion, that the internal laminae of the periosteum became ossified in the adult, con- sidered that as a means by which all the aforementioned in- sertions into it, became identified with the bones. This will account for the great degree of tenacity with which they ad- here, and the immense force they are capable of sustaining, without being detached from their insertions. In this ten- dency to ossify, the periosteum manifests a great similitude to other fibrous membranes, as the dura mater, the sclero- tica, and the tendons. The use of the periosteum is to conduct the blood vessels to the bones; to protect the latter from the impression of the muscles, and other organs, which come in contact with them; to keep the ossification of the bones within its proper bounda- ries, and to give shape to them ; and, finally, as has been suggested by Dr. Physick, it exerts a very happy influence in turning from the bones suppurations in their vicinity, which would otherwise be pernicious to them. SECT. II.—OF THE MEDULLA, AND ITS MEMBRANE, CALLED THE INTERNAL PERIOSTEUM. The greasy substance within the bones, which, from its resemblance in position to the pith of vegetables, has obtained the name of medulla or marrow, is contained in a very fine cellular and vascular membrane, lining the internal cavities of the bones, and sending into their compact substance very delicate filaments. The existence of this membrane has been denied, but it may be established by sawing a bone in two, and approaching the cut end to the fire, so as to melt out the marrow, or by immersing it in an acid, in which case the membrane becomes crisp and distinct Its delicacy is so extreme, that it can only be compared to a spider's web. In * Anatomie Generale. MEDULLA AND ITS MEMBRANE 17 this state it may be traced, lining the whole cylindrical cavity of the long bones, and extending itself to their extre- mities. It also exists in the diploic or cellular structure of all the other bones, but it is scarcely possible to demonstrate it there, in a very distinct manner owing to its extreme tenuity. The medullary membrane is composed principally of the minute and numerous blood vessels spent upon the internal surface of the bones, aided by a very fine, soft cellular tis- sue, merely sufficient in quantity to fill up the meshes be- tween the frequent anastomoses of its vessels. From the latter cause, it is compared to the pia mater and to the omen- tum. It has been stated, that its blood was derived from the nutritious artery, which communicates freely with the other arteries of the bones. This membrane is so arranged as to form along the course of the blood vessels small vesi- cular appendages which contain the marrow, and bear some analogy to a thick bunch of grapes, hanging from the several pedicles of the stem. Its nerves are extremely small; they enter by the nutritious foramen, and have been particularly observed by Wrisberg and Klint.* They have not been traced ramifying in the substance of the bone, but follow for some distance the course of the principal arteries. With the exception of Mr. Cruik- shanks solitary injection of a vertebra, no lymphatics have been observed satisfactorily on it, and such trunks as are supposed to come from that source, have not been traced nearer to it than the orifice of the nutritious canal. Some differences exist in the nature of the contents of the medullary membrane; for example, that part of it which is reflected over the cells in the extremities of the long bones, and in the whole interior of the flat and of the thick ones, contains a much more bloody and watery marrow than what is found in the cylindrical cavities of the long bones; the latter, indeed, resembles closely common adeps, presenting no essential difference from it. These circumstances have given occasion, without a material distinction of texture, to divide the medullary membrane into two varieties. * Beclard, loc. cit. VOL. I.—Cj 18 SKELETON That variety contained in the cellular extremities of the long bones, and in the spongy bones generally, is in a superior degree vascular. The part within the meshes of its vessels is, however, so imperfect, that Bichat declared his inability to find it, that the number of the fine vessels was what gave fallaciously, the appearance of a membrane; while, in fact, the intervals between them, were large enough to allow7 the fat to come into contact with the naked bone. The probability of this deficiency is confirmed by the cir- cumstance, that no one pretends to have found a membrane in the microscopical pores of the compact substance, yet the existence of fat in it is proved by its becoming greasy when insulated and exposed to heat. It is from the great abun- dance of blood in this variety of the medullary tissue, that the proportion of its adeps is small. The second variety of medullary membrane is displayed in the cells of the diaphyses or bodies of bones. Its membranous cells communicate freely with one another when the mem- brane is entire, but according to the observations of Bichat, not with such as are in the epiphyses of the bones, and the line of demarkation is abrupt and well marked. This is proved by attempts to inflate the one from the other; the air, in such cases, passes with great difficulty. The texture of this me- dullary membrane, from its extreme delicacy in a natural state, is rather obscure, but it is occasionally well developed in disease. Its sensibility has not been very apparent in such cases of amputation as 1 have seen, though it is said by some to be extremely exquisite. In whatever degree its sensibility exists in different subjects, it is always more apparent in the middle than near the extremities of the long bones, which may be accounted for by its nerves always entering at the nu- tritious foramen, and extending from there towards the ex- tremities. The medullary membrane, besides its use in secreting the marrow, is highly serviceable to the nutrition of the bones as proved in the experiments of Trojat, who, by destroying it produced their death, and an artificial necrosis, which was cured in the usual way by a new secretion of bone from the DEVELOPMENT OF BONES. 19 periosteum. The marrow which it contains in the adult is not perceptible in the foetus. Moreover, the quality of this marrow is varied by disease; in consumption, dropsy, and other ailments attended with great emaciation, a consider- able part of it is absorbed, and a serous fluid deposited in its place, a circumstance well known to those who clean skele- tons. CHAPTER III. ON OSTEOGENY. sECT. I.—OF THE DEVELOPMENT OF THE BONES. From the early embryo state to the completion of the .skeleton, three stages are observable in the progress of ossifi- cation ; the first is mucous or pulpy, the second cartilaginous, and the third osseous. I. The mucous stage is observable at a very early period after the embryo has been received into the womb, and pre- sents itself under two modifications. In the one, from the general softness of the whole structure of the embryo, and from the apparently homogeneous nature of its constituents, the mucous rudiments do not distinguish themselves from the other parts. This condition, however, is soon changed into one, and that before the expiration of the first month, in which it is caused to assume a solidity and colour, which mark it off, both to the eye and to the feel, from the still softer parts surrounding it. II. About the expiration of the first month the mucous stage is converted into the cartilaginous, and the consistence of the bones then increases continually by the accumulation of gelatine. Bichat makes a remark on this subject which has 20 SKELETON. been confirmed by the experiments of Scarpa, though erro- neous deductions have been made by the latter: that we do not see, during the formation of the cartilages, those longi- tudinal striae in the long bones, radiated in the flat, and mixed in the thick bones, which distinguish the osseous state. The cartilaginous state presents another peculiarity worthy of observation; all the bones which in a more ad- vanced stage are to be united by cartilage, as the vertebras, those of the pelvis, and of the head, make collectively but one piece; while those which are to be united by ligament, and consequently to be moveable, as the femur, the tibia, the cla- vicle, and so on, are respectively insulated. In the cartila- ginous state the bones have neither cells or medullary cavities, and consist in a solid, homogeneous mass, the form of which is sufficiently definite: and has its surface covered by peri- osteum. The flat bones of the cranium seem to be an exception to the general rule of a preliminary cartilaginous state, and are commonly thought to be such. The appearance is delu- sive, from the cartilage being extremely soft and thin, and concealed by the pericranium on the one side, and the dura mater on the other, but a careful dissection enables one to distinguish it from this double envelope.* III. The calcareous matter begins to be deposed when the rudiments of the bone have become entirely cartilaginous, with the exception of a few mucous points. In certain bones this change is observable about the commencement of the second monthf after conception, J. F. Meckel has placed it about the eighth week. The colour of the cartilage first be- comes deeper; and in its middle, where ossification is to com- mence, is of a well marked yellow. The blood vessels, which before this carried only the transparent part of the blood now dilate, so as to admit the red particles, and a red point is perceived called the punctum ossificationis, from its re- * Bichat, loc. cit. f Beclard, loc. cit. Bichat, loc cit DEVELOPMENT OF BONES. 21 ceiving the first calcareous deposite. This deposite is always near the very centre of the cartila ginous rudiment, and not at its surface, the portion of cartilage nearest to it is of a red colour; but, a little further off, opaque and hollowed into ca- nals. The ossification increases on its surface, and in its in- terstices, by continual deposites, which are always preceded by the condition of the cartilage just mentioned. The canals of the cartilage transmit the blood vessels, and are large at the beginning of ossification, but, as the process advances and is completed, they diminish gradually, and finally disappear. The progress of ossification is somewhat modified in the three classes of bones. In the long bones a small ring is observed to form early near their centre, and to be perforated on one side by the nu- tritious artery. This ring has its parieties thin but broad, and its cavity is the beginning of the medullary canal. It is formed of very delicate fibres which advance towards the ex- tremities of the bone,* and at the same time increase in thickness, so that at birth, the body or diaphysis is generally finished. Commonly at a period subsequent to birth, but differing in the several bones, their cartilaginous epiphyses also begin to ossify, by the development in their centre of points of ossification, which present the phenomena men- tioned in the last paragraph but one. The cartilaginous state gradually disappears by retiring from the articular end of the bone towards its diaphysis, and, just before its com- plete removal, it appears as a thin lamina, gluing the end or epiphysis of the bone to its body. Several of the apophyses of the long bones are also formed from distinct points of ossi- fication. By the time that these several parts of a long bone are all fused into one piece, and the structure consolidated, the individual is from sixteen to eighteen years of age, ac- cording to the sex. The ossification of the flat or broad bones begins by one or more points, according to the bone being of a simple shape • Bichat, loc. cit. 22 SKELETON. as the parietal; of a double shape or symmetrical, as the frontal, where there are two points of ossification ; and of a compound shape, as the occipital and temporal, where there are several points. The commencement of ossification Jherc is also manifested by the appearance of a red vascular spot, in which the osseous matter is deposited, and from which it pro- gresses in radiated fibres. The periphery of this circle of rays, presents intervals between the fibres giving it the ap- pearance of the teeth of a fine comb; these intervals are subsequently filled up by the sections of radii starting from them, and so on successively till the bone is finished. In the infantile head the several radii grow with a pace nearly equal, so that where the bones are angular, the angles being most distant from the centre of ossification are finished last of all, from which arise the fontanels. Where the bones are intended to be kept distinct from each other, their fusion is prevented by a membranous partition, but when they are to coalesce into one piece, only cartilage is found, which is subsequently absorbed. In some of the flat bones, as the sternum and the sacrum, there are first of all a great many distinct points of ossifica- tion, which quickly unite into a smaller number, they then remain stationary for a number of years, but finally all unite into but one piece. The ossification of the thick bones, begins by one or more points, according to the simplicity or complexity of their figures. The bones of the tarsus and of the carpus have each. but one point, while those of the spine have several. The two former are almost entirely cartilaginous at birth. The remaining phenomena of ossification in these several bones are the same as have been mentioned. SECT. II.—ON THE MANNER IN WHICH THE BONES GROW . After the cartilaginous condition of the bones has been supplied by the complete deposite of osseous matter, and they are finished with the exception of the epiphyses being fused GROWTH OF BONES. 23 into the body, the bones still continue to grow till the indi- vidual has reached a full stature. This is effected by the suc- cessive addition of new matter to the old. The long bones lengthen at their extremities, this is proved by the follow- ing experiment of Mr. Jno. Hunter.* Having exposed the tibia of a pig, he bored a hole into each extremity of the diaphysis and inserted a shot, the distance between the two shots was then accurately taken. Some months afterwards, when the animal had increased considerably in size, the same bone was examined and the shots were found precisely at their original distance from each other, but the extremities of the bone had extended themselves much beyond their first distance from the shots. The flat bones increase in breadth by a deposite at their margins, a circumstance which has been known a long time, but it required the ingenuity of Mr. Hun- ter to prove conclusively that the long bones increase in length by a similar process, and not by interstitial deposite, as Duhamel thought. This observation explains most satis- factorily the use of the cartilage between the diaphysis and the epiphysis in all bones; that it is merely interposed for the purpose of offering the least possible resistance to the new osseous fibres, which grow from the epiphyses and from the diaphyses; and that it is kept for this end, without any ma- terial change in thickness, from the fourth or fifth year to the sixteenth or eighteenth, when it disappears, because there is no longer any use for it, in consequence of the bones hav- ing attained their full size. The Epiphyses are then manifestly intended to favour the elongation of the bodies and the development of the extremi- ties of the long bones ; to suit the same purposes in some of the flat bones, as those of the pelvis, and to permit the gene- ral development of the bodies of the vertebrae. Their ossi- fication commences in some bones about fifteen days before birth, as in the inferior extremity of the thigh bone, and in others, as those of the ossa innominata, not till the fifteenth * Transactions of a Society for Improvement, vol. ii. London, 1800 Experiments and Observations on the Growth of Bones. 24 SKELETON. year or thereabouts. Many of the processes from the bones are also epiphyses, as the trochanters of the os femoris, the tuber of the ischium, the acromion scapulae, the seven pro- cesses of a vertebra, and so on, and arc developed in the same way. The time at which they all are thoroughly fused into the bones to which they belong, extends from the fifteenth to the twenty-fifth year, depending upon the individual bone, and upon varieties of constitution in different persons. The increase in thickness of every bone depends upon a continued secretion from the internal surface of the perios- teum, at first soft and mucous, then osseous, when this secre- tion is arrested the bones cease to grow in thickness, which commonly occurs sometime after they have attained their full length. The changes which subsequently take place in them are those of interstitial deposite and absorption, the former is well exemplified in inflammations of the bones, and in spina ventosa, the latter in the diminution of the bones in extreme old age, and in the loss of the alveolar processes. There is no period of life in which this interstitial absorp- tion and deposite is not continually occurring, but it is much more rapid in young and growing animals than in the adult and old. The experiments of Mr. Hunter and of Duhamel, show, that when a growing animal is fed upon madder (rubia tinctorum) the bones are quickly coloured by it; when the madder is withheld, the bones become again white ; and that the first appearance of the restoration of the latter de- pends upon a white lamina being deposited on their surface. The madder under such circumstances is a long time in get- ting out of the bones. I fed a young pig for one month on it, mixed with other food. At the expiration of the suc- ceeding five months, the animal having grown very consi- derably, was killed. The interior lamina; of all the bones continued to be deeply tinged, while their surface from the deposite of new bone had become white From this it would appear that deposite is a very permanent thing in bones : it of course must prevail much over absorption, else their growth would be arrested. At the same time that the periphery of each bone is in-- GROWTH OF BONES. 25 creasing in its dimensions, the medullary canal is also aug- menting; this arises from an absorption going on inter- nally, while the deposite is making externally. Duhamel* proved this by a curious experiment. He surrounded a cylindrical bone of a young animal with a metallic ring ; on killing the animal some time afterwards, he found the ring covered externally by a secretion of bone,f owing to the growth of the latter, and the medullary canal as large as the ring itself. Notwithstanding the obvious conclusion from this experiment, he made the mistake of supposing that the bone had enlarged by expansion, and not by a deposite ex- ternally with an absorption internally. As the individual advances in life, the cylindrical canal in the centre of the long bones continues to enlarge in size by the internal absorption, so that the parietes of the bones, which in early life were much thicker than the canal, and in the adult about the same diameter, become exceedingly thin in old age, resembling thereby a stalk of Indian corn, with the pith scooped out4 The cells of the cellular structure in the several bones also enlarge, whereby the whole weight of the bones is much decreased in the very aged. The parietes of the cranium are exempted from the latter change, for there is rather a tendency in them to the absorption of the diploe, and the approximation of their tables. The bones also become more brittle in old age, in conse- quence of the increase of calcareous, with a diminution of gelatinous matter. The reverse being the case in infancy, they are more flexible than in the adult, and can bear even to be twisted or bent without breaking. * Mem. de l'Acad. Roy. des Sciences, an. 1739-41-43-46. f If a string be tied around a growing tree, the same thing takes place, and it is finally shut up in the ligneous part. + There are several examples of this in the Anatomical Museum. More rarely the reverse takes place, and the cavity is filled up; of this there are also specimens. VOL. I.—D 26 SKELETON SECT. III.—ON THE FORMATION OF CALLUS. As this is a consequence of bones being fractured, and a mean that nature takes to repair the accident; there is some resemblance between it and the primitive formation of bone. Owing to the rupture of the blood vessels of the bone, of the periosteum, and of the medullary membrane, and frequently of the vessels of contiguous parts, the first effect of the acci- dent is an effusion of blood into the cavity of the fracture. The several contiguous soft parts swell, become hardened and inflamed : in the mean time an absorption of the blood is proceeding, while an effusion of coagulating lymph from the ruptured vessels occurs in the cavity of the fracture. A ring, the thickest part of which is precisely over the seat of the fracture, is formed by the lacerated parts ossifying; they also form in the interior of the bone a sort of osseous pin. Till this moment the bone itself remains unchanged, with the exception of a coating of coagulating lymph on its broken faces, but now its extremities begin to coalesce or fuse them- selves into each other, the superfluous bony matter (the ring and the pin) being no longer necessary, is absorbed, and the cavity of the bone with the membranes of the latter are re- established.* In this case it will be seen that the deposite of coagulating lymph into the cavity of the fracture, corre- sponds with the mucous rudiments of the foetal bone, and that the remaining phenomena of its ossification are the same. Some physiologists have attempted to give to the perios- teum the exclusive credit of the formation of callus, the view is erroneous, because experiments show, that even where the periosteum is stripped designedly from the fractured ends of bones, they nevertheless unite, and the periosteum is restored when the callus is formed. The probability then is, that all the blood vessels (from whatever source they come) which penetrate the organized coagulating lymph secreted between • J. Hunter, paper by Mr. Home, in Trans, of Society for Improven...;i? London, 1800. FORMATION OF CALLUS. 21 the fractured extremities, convey and deposite calcareous matter. The celebrated Bichat and some others were of opinion, that in every case of fracture where the ends of the bones are not kept in contact, granulations spring up from the ruptured surfaces of the bone, and of its membranes; that these granulations first receive into their interstices a soft gelatinous deposite, then a cartilaginous one, and finally a calcareous one, by which the bone is united. This process, however, is much more common in compound fractures which suppurate, and may be considered rare in simple ones. When the calcareous matter begins to take a place in a forming callus, if the part be much moved the process is arrested, the blood vessels no longer deposite even if they carry calcareous materials, and an artificial joint is formed. The proper period of restoration being once passed, the vessels sink into an inactive state, from which they have little or no disposition to rouse themselves. Under these circumstances, Dr. Physick proposed, many years ago, the introduction of a seton through the cavity of the fracture, and the retaining of it there for a long time, for the purpose of stimulating the vessels. The plan has now been repeatedly tried, with com- plete success, on the cylindrical bones, and in one instance upon the lower jaw.* Callus is formed much more speedily in young persons than in old; every now and then, however, we meet with cases in which the rapidity of its deposite in the latter is re- markable. I have, for example, lately treated a female of ninety for a simple fracture of the os humeri, which was re- covered from at the end of five weeks. * Dorsey's Elements of Surgery. Philadelphia Medical and Physical Journal, &c. 2S SKELBTO>, CHAPTER IV. GENERAL ANATOMY OF THE NATURAL SKELETON CONTINUED. SECT. I.--OF THE CARTILAGINOUS SYSTEM. The Cartilages supply the place of bone in many parts of the human skeleton, as in the space between the ribs and sternum, in the larynx, in the internal ear, in the nose, and so on. They are also to be found in all the moveable, and in several of the immoveable articulations. Wherever placed, they may be recognized by their whiteness, by their flexibi- lity, by their great elasticity, and by a hardness only short of that of the bones. There are many animals whose skele- tons are entirely cartilaginous, as the chondropterous or cartilaginous fishes, so excellent a substitute is cartilage for bone. Cartilages have neither canals or cells in them. They appear homogeneous : and, upon a superficial inspection, present neither laminae or fibres. The immersion of them in boiling water dissolves into a jelly such as are found upon the articular surfaces of the bones, and a few others ; but, such as supply the place of bone, though softened by the process, are not rendered by any means so gelatinous. Their chemical analysis, according to Mr. I. Davy, is °-cla- tine 44.5 ; water 55.; phosphate of lime 0.5. The testimony of different experimenters upon the latter point does not coin- cide, and their results mu.st vary according to the kind of cartilages, and the period of life. Cartilages are composed of a tissue exclusively their own, and of parts which they have in common with other organs.' The first has some very distinguishing properties. It resists putrefaction, either with or without maceration, longer than any other tissue, except the bones. In the midst of gan- grene, it preserves its appearance almost unchanged. Boiling gives it a yellow colour, causes it to swell, and, if protract- CARTILAGINOUS SYSTEM. 29 ed, the gelatinous portion is dissolved. When dried, it be- comes of a demitransparent yellow, diminishes in bulk, and loses its elasticity; in these respects resembling ligaments and tendons. Cellular substance exists, in very small quantities, in car- tilage, and is, therefore, not readily demonstrated; it is, however, made manifest by maceration, and by the action of boiling water; the latter, by dissolving the gelatinous por- tion, leaves a membranous and cellular structure. It is also stated, that in certain diseases the gelatinous portion being less abundantly secreted, the cellular is left in a soft, spongy condition. In a healthy state, no blood vessels can be seen in carti- lages ; yet there are the strongest proofs of a species of cir- culation going on in them, either by very fine capillary ves- sels, or an interstitial absorption. All experienced anatomists have seen, in subjects affected with jaundice, the entire car- tilaginous system losing its brilliant whiteness, and becoming of a light yellow : also, the conversion into bone, in extreme old age, to which all cartilages, with but few, perhaps no exceptions, are subject; and, as this ossification sometimes begins in the centre of the cartilage, it proves that the cal- careous matter has been conveyed there by some kind of channel. Neither absorbents or nerves have been traced into them, and it is not possible to prove exclusively their existence by the circumstances of disease. We only know, that in inflam- mations of the joints terminating by anchylosis, the carti- lages are absorbed; and,.that in some cases even without evident inflammation, the cartilage is removed from a joint as if it had been worn away. Ulcerations of the arytenoid cartilages are spoken of as common, by the French anato- mists ; but it has not occurred to me to see either them or any others in this state : Dr. Physick's experience is also the same with my own. Possessed of no animal sensibility in the natural state, it is doubtful whether they ever have it, or can inflame, as the pains in inflammations of the joints may arise from the synovial membrane. 30 SKELETON. In the embryo, the osseous and cartilaginous systems arc confounded, so as to present a homogeneous, mucous or pulpy appearance; they only become distinct by the deposite of calcareous matter in the bones; when the latter are somewhat advanced, the cartilages, which are to remain such, have also additional consistence, and more of a proper cartilaginous look; but the appearance is generally unsatisfactory by which one can certainly distinguish the cartilages, that are to remain such, from the cartilaginous rudiments of the bones. The following circumstance, however, is pointed out by Bichat: In the cartilages of ossification, there is a vascular net-work between the cartilage and the ossification which has occur- red, and owing to the interposition of it, the two may be easily separated. But, in the permanent cartilage, this net-work does not exist between the proximate surfaces, consequently they adhere with a tenacity not admitting of a rigid separation from one another. , As the individual reaches adult age, the cartilages acquire. the strength, whiteness, and great elasticity which distin- guish them. In old age they become yellowish, more brittle, and are, as said, generally disposed to ossify. Those of the ribs and larynx are frequently ossified at forty years of age. The ossification of those of the moveable joints is rare, and begins at a more advanced period. In the two first it begins commonly near their centre, and in the last on the surface. SECT. II--ON THE ACCIDENTAL DEVELOPMENT OF CARTILAGES. The unnatural development of cartilages, in the tissues and organs of the body to which they are very slightly al- lied in their nature, is a circumstance by no means uncom- mon, and is met with annually, in most of its varieties, in our dissecting rooms. As there is a great disposition in such cartilages to ossify, they are presented in the several gradations from a soft gelatinous body to that of perfect bone. They occur in the articulations; i» the lungs, and form there fistu- PERICHONDRIUM. SI lous passages; very frequently on the surface of the spleen ; in the pleura ; in the fibrous coat of the large arteries, par- ticularly the arch of the aorta ; and in the semilunar valves of the same ; in the ovarium, when it becomes dropsical; and also in many other parts of the body. The cartilages which are found loose in the joints and floating about there, begin, for the most part, in the fibrous structure* exterior to the synovial membrane; the latter is protruded inwards by them and gives them a covering re- sembling the finger of a glove. As these bodies are small and rounded, when they protrude into the joint the synovial membrane forms a pedicle or base to them, which is finally ruptured, and then the cartilage becomes loose. These bodies are generally ossified in their centre, of course they have gone through the usual progress and phenomena of ossi- fication. The other forms of preternatural cartilage are much disposed to ossify in the arteries^ but not so much so in the other viscera. In these cases they are laminated and adhere by their surfaces, very closely, to the contiguous structure, so as to be membranous. Mr. Laennec has seen a cartilaginous transformation of the mucous membrane of the urethra; Mr. Beclard of the mucous membrane in the vagina, attended with prolapsus uteri; and also of the pre- puce of an old man who had a phymosis from birth. SECT. III.-—OF THE PERICHONDRIUM. All the cartilages, except the articular ones, are invested by a membrane called perichondrium. It is best seen on the larynx, and on the cartilages of the ribs. Its structure is fibrous, and corresponds so fully with that of the perios- teum that it may be considered the same sort of membrane. It is, however, less vascular than the periosteum, and ad- heres to the cartilages with less force, owing to the fibrous connexion between them being not so abundant. Bichat's experiments prove that the cartilage is much less affected by * Beclard, Anat, Gen. 32 SKELETON. the loss of this membrane, than the bone is by that of the periosteum; its uses are no doubt the same. SECT. IV.—OF THE ARTICULAR CARTILAGES. To this class we refer, exclusively, such as adhere by one surface to the articular facings of the bones, and present the other surface to the cavity of the joint. Every moveable, and some of the immoveable articulations, have their surface uniformly thus incrusted, to a thickness varying from the fraction of a line in the smallest joints, to one line in the largest. The cartilage itself is rather thinner near the mar- gin of the articular surface, when the latter is convex, than it is near the centre ; on the contrary, when the surface is concave, the cartilage is thickest near its periphery. These cartilages, when subjected to a maceration of six months, are stripped of the reflection of synovial membrane, which covers their articular surfaces, and are resolved into fibres, one end of which adheres to the bone and the other end points to the joint. If the preparation be then dried the distinction of fibres becomes more manifest. The most successful injections, closely examined with a microscope, demonstrate the defect of blood vessels in them. The vessels are uniformly seen to terminate at the circumfer- ence of the cartilage and at the face which adheres to the bone, but never to penetrate it. Their organization is, therefore, extremely simple, and such as subjects them to but few morbid alterations. When partially removed from the bone the latter occasionally reproduces them, but the edges of the new and of the old production do not unite. I have, in cases of inflammation of the joints, seen the fibres of these cartilages much longer than usual and detached from each other. When a joint is laid open by a wound and suppurates, the cartilage softens and disappears from the circumference to the centre.* * Beclard, Anat. Gen. The same author speaks of the idiopathic ulce- ration of the cartilage, as a result of its inflammatian. Dr. Physick whose experience is equal, denies either the one or the other. CARTILAGINOUS SYSTEM. 33 CHAPTER V. OF THE FIBRO OR LIGAMENTO CARTILAGINOUS SYSTEM. This set of organs has been placed, by anatomists, indis- criminately in the cartilaginous or in the ligamentous sys- tems, in consequence of its participating in the characters of both; it, however, from its importance, should have a dis- tinct position. There are three varieties of this system. The first presents itself in the membranous state, and is represented by the external ear, by the alae of the nose, by the cartilages of the eye-lids, and by the trachea. The second is represented by the inter-articular cartilages of the moveable articulations, as of the knee, the wrist, lower jaw, and also by the intervertebral matter which holds the bodies of the vertebrse together. x\nd the third is represented by the trochlear and sheaths, formed on the surface of bones for the gliding of tendons. The principal constituent of this system is a strong fibrous matter, which is intermixed with the cartilage, and has in some places its surface covered by the latter. The fibres even by superficial observation may be traced in various direc- tions, in some places they are parallel, in others intermixed and crossed very much, in others concentric. Their strength is of the first order. The cartilaginous part fills up the in- tervals between the fibres, and gives to the whole structure its whiteness and elasticity. The Fibro-cartilages may be converted by the action of hot water into gelatine, but the process is slower than in the simple cartilage. The membranous or first variety, differs however from the other two in this respect, for if it can be reduced at all into gelatine, the quantity it yields is not per- ceptible. This system is destitute of perichondrium, with the excep- tion of the first variety, in which it is distinguishable ; but the others either adhere to the bone, or are covered by a VOL. I.--E .H SKELETON. synovial reflection, their margins adhering in such cases to the contiguous ligamentous structure. There is a very small quantity of cellular tissue in this system. Artificial injection manifests but few blood vessels in it, if the animal, however, he strangled for the purpose, the blood by accumulating in the capillaries becomes suffi- ' iently apparent. CHAPTER VI. OF THE LIGAMENTOUS OR DESMOID TISSUE. SECT. I. The Desmoid Tissue (Textus Desmosus) is very generally diffused in the human body, has a very close connexion with the cellular texture, and is continuous with it in divers places. It may be known by its whiteness, the firmness and unyielding nature of its materials, and its fibrous arrange- ment. It is most commonly employed in fastening the bones to each other at their articulations, and in enveloping the muscles,(but is also applied in many other ways. Its appli- cation in the former is our present object, but before that is particularly noted, it will be useful to enter into some general considerations in regard to its intimate structure, and the observations now made can be applied on all other occasions when this tissue is in question. A desire to generalize, and consequently to simplify, has induced anatomists to seek for some fountain or source from which all the reflections and applications of the desmoid tissue might be traced. The Arabians thought that the dura mater was this source, and the error was sanctioned for a long time by the authority of Sylvius. The celebrated Bichat, in LIGAMENTOUS TISSUE. 35 tracing the connexions of this tissue, finding that all its points of application might be traced either mediately or directly to the periosteum, considered the latter as its centre, as the heart is the centre of the circulation, and the brain of nervous energy, not that he thought the periosteum radiated its influence on all its dependent organs, but because ana- tomical inspection demonstrated all the fibrous organs con- nected with it, and communicating through it with each other. The late Professor Bonn, of Amsterdam, reversed the idea of Bichat, and considered the aponeuroses of the ex- tremities, and of the trunk, which send their partitions be- tween the muscles, and down to the periosteum and joints, as the much desired centre of the desmoid system. The lat- ter idea has been reiterated by others, and the supposed emanations from the superficial aponeuroses diligently traced. As a means of studying the position and connexions of parts, notwithstanding the construction is a very forced one, which makes desmoid tissue cellular membrane, and cellular mem- brane desmoid tissue, alternately, so as to suit the arrange- ment of the anatomist, instead of that of nature ; yet, any or all of these plans have their use and may be followed advan- tageously, after the study at large of the human fabric. The desmoid tissue is essentially fibrous, but without a uni- form arrangement, as its fibres are either parallel, crossed, or mixed. In some places the fibres are very compact, and sepa- rate with difficulty, but generally prolonged maceration will eause them to part into filaments as fine as the thread of the silkworm. Anatomists differ in regard to the ultimate struc- ture of these fibres. By M. Chaussicr they are thought to be primitive and peculiar; Mascagni supposed that they were lymphatics enclosed in a vascular web ; Isenflam, that they were cellular substance embucd with gluten and albumen. And Mr. Be'clard, observing that maceration resolves them into a species of mucous or cellular substance, teaches that they are the latter in a condensed state. Bichat's opinion is probably correct, that the tissue is peculiar, and that macera- tion only brings into view the cellular substance which unites its fibres. Though maceration and chemicai management, 36 SKELETON. evolve some striking coincidences with cellular membrane, yet in the natural and ordinary state there are some very strong points of difference from it. Among these may be remarked its great want of elasticity, which causes it to tear sooner than to stretch, and in general anasarca, its being only very partially affected, merely rendered a little more moist and tumid, which even then may arise from the small quantity of cellular substance in it. Many parts of it, how- ever, are unaffected in the latter way, as the tendons and their sheaths. This tissue naturally contains a considerable quantity of water, which it loses by exposure to the air, it then is much reduced, and becomes hard and yellowish, and is made semi-transparent by being put into spirits of tur- pentine. The desmoid tissue, by being subjected to the heat of boil- ing water, contracts, becomes more solid, and is elastic; but, if it be continued there, it gradually softens, becomes semitransparent, and gelatinous. The mineral acids reduce it to a pulpy state, and, if concentrated, will dissolve it en- tirely. The alkalies loosen its texture, cause the fibres to separate easily, and to assume a diversity of colours. It putrifies but slowly, in this respect being next to the carti- lages. The strength of this texture is remarkable, and adapts it to the sustaining of enormous weights, a faculty which is continually in requisition, both to retain the articular sur- faces of bones in contact, and the muscles and tendons in their places. It is well known that the patella, the olecra- non, and the os calcis, break frequently before their tendinous attachments will give way. In the history of punishments,where criminals have heen attached to four horses, it is said that it has been found necessary to use a knife to assist in their dis- articulation. All these phenomena occur when abrupt vio- lence is resorted to, so little are the ligaments disposed to yield ; but, when the causes of distention act slowly and gra- dually, as in dropsies of the joints, the fibres separate, and are sometimes completely disunited. When the distending cause ceases to operate in the latter case, the ligaments have LIGAMENTS OF THE JOINTS. 37 power of contracting in the same gradual way, and of re- storing themselves. Some of the desmoid tissues, besides having their fibres sur- rounded and their interstices occupied by cellular substance, contain a very small quantity of oily or fatty matter. This is not very obvious in their recent state; but, by drying them, it will be seen in small quantities on their surface, like a greasy exudation ; this probably comes from the cellular substance jn them. They are furnished but sparingly with blood ves- sels, which, for the most part, are capillary. The perios- teum and the dura mater are, however, exceptions to this rule. Lymphatic vessels have been observed in some of them, but it is doubtful whether they have nerves.* The sensibility of this system is extremely obscure, and is not manifested under the usual mechanical and chemical irri- tants^ it may, however, be elicited by communicating to the joints a twisting motion, as the experiments of Bichat prove. Inflammation augments their sensibility, in wrhich case it becomes extremely acute, as in gout and rheumatism, or any other cause productive of it. SECT. II.—OF THE LIGAMENTS OF THE JOINTS. The ligaments, properly speaking, are those organs which tie the bones together, and in the moveable joints are either capsular or funicular. The first are like a bag open at the ends, at either of which the articular extremity of a bone is included. These are much more complete in some joints than in others ; the shoulder and the hip joints afford the most perfect examples; in other joints they are divided into irregular fasciculi of fibres, permitting the synovial membrane to appear in their interstices, and sometimes they are still more widely separated. The funicular ligaments are mere cords, extending from * B^clard, Anat. Gen 38 SKELETON. one bone to another; some of them arc flattened, some round- ed, and others oval or cylindroid. They are variously placed ; in some instances they are within the capsular liga- ment, and in others on its outer surface, sometimes so blended with it as not to be separated without an artificial dissection. Their names are derived either from their position or shape, and are generally sufficiently appropriate. SECT. III.--OF THE SYNOVIAL ARTICULAR CAPSULES. Each moveable articulation is lined by a membrane re- flected over the internal face of the capsular ligament and the articular cartilages. This membrane is a perfect sac, and, unlike the capsular ligament, has no opening in it. It is remarkably distinct where it is not attached to the articu- lar cartilages; and, by being inflated, is caused to protrude in small vesicles, or pouches, between the fasciculi of the ligamentous structure. Its connexion with the cartilage, and its continuation over it, is not quite so obvious, and requires more management to demonstrate it; it is, indeed, so thin and transparent at this part, and adheres so closely, that its existence there has been questioned, but may be proved in a variety of ways. By maceration it becomes so loose, that, with a pair of forceps, shreds of it may be raised along the whole extent of the cartilage. If a flap of cartilage be raised up by a knife, its base being left attached, in attempting to tear away the base it will be found that the synovial mem- brane is continued from this base to the contiguous cartilage. Saw a bone through to its articular cartilage, then tear through the cartilage gently, in which case the continuity of the synovial membrane will also be manifested. The synovial capsules are liable to a fungous degeneration, which occurs equally upon the cartilaginous and capsular portions of it. Factitious bridles sometimes form in the joints at- tached indiscriminately to either portion of the synovial mem- brane. Mr. Beclard says, that protracted inflammation will finally redden the cartilaginous portion, and that it extends SYNOVIAL ARTICULAR CAPSULES. 39 from the circumference to the centre, the hues being lighter the nearer it is to the latter. It has not occurred to me to meet with this proof; though I have made frequent dissections in subjects, of inflamed joints, the redness has always ceased at the margin of the articular cartilage: Dr. Physick's expe- rience, most valuable on all occasions, affords support to my own. During last winter I had an opportunity of investi- gating, somewhat fully, this point, in a subject, all of whose large joints were in a state of inflammation. from these several proofs the fact is established, that the synovial mem- branes are bags closed at both extremities, and differ thereby from the capsular ligaments. The Synovial Capsules are white, thin, semi-transparent and soft. Wherever there is a deficiency of capsular ligament they adhere to the contiguous cellular substance, and are so blended with it as to appear absolutely continuous. Dissec- tion, inflation, and maceration, prove them to be lami- nated, and develop their structure in such a way that it re- solves itself into a cellular tissue, the more interior layers of which had been in a very compacted state. In all this they resemble the serous membranes generally, and are ranked among them ; Bichat therefore considers them only as an in- terlacement of absorbents, and of exhalants. But for the further exposition of this point, see the article on the Serous Membranes. The Synovial bags have on their outer surface, but pro- jecting into the cavity of the joint, adipose cushions of dif- ferent sizes, called the synovial glands of Havers, from which till lately, it was supposed that the lubricating liquor of the joints is exclusively secreted. These cushions have their pro- jecting margins fringed and unusually vascular, and occupy the small spaces left between the articular faces of the bones. As they are covered by the synovial membrane, they no doubt assist in the secretion of the synovia. The moveable articulations are all furnished with the fluid called synovia; this name was given to it by Paracelsus, from its resemblance to the albuminous part of an egg, to the 40 SKELETON consistence and colour of which it has a close affinity, and like it, is thick, ropy, and somewhat yellowish. The chemi- cal analysis of it indicates the presence of water, albumen, and a kind of incoagulable mucus. It was once supposed to be a mixture of serum, with the adipose matter of the bones, which found its way into the joints by transudation, but as it contains upon experiment no oil, the opinion is evidently er- roneous. It is secreted from the whole internal surface of the synovial membrane, and, perhaps, in greater quantities from the fringed fatty cushions in the joints in consequence of their increased vascularity. Mr. Beclard teaches, that it is neither a follicular, or a glandular secretion, or a transu- dation, but a perspiration, in which a perfect equilibrium is kept up between its exhalation and its absorption Its use is to diminish friction, and consequently, to facilitate the slid- ing of the bones upon each other. BOOK I. FART IX. Of the Bones Individually\ and their Articulations. The several textures of the body are so interwoven, that a person cannot take up the consideration of one alone, and pursue it through all its localities, without leaving behind, for the time, some one or more of the others. This circum- stance has always perplexed writers on anatomy, and left them under various impressions concerning the best point of departure and method for pursuing their descriptions. Rea- sons of sufficient value may be urged for almost any arrange- ment, and each one will have some peculiar advantages that the others have not, and which will cause it to appear supe- rior to the rest, to the understandings of its advocates. For a course of study which is intended to be physiological and surgical in its combinations, the usual practice of beginning with the skeleton is perhaps the most advantgeous; the young student will not, however, understand that the skele- ton has any natural claim to this precedence, but that it is only conceded, for the purpose of laying a foundation for the more easy and intelligible description subsequently, of other parts. In this respect, the human frame may be com- pared to a varied and extended landscape, the multiplicity of whose features and the variety of objects spread over its surface, bewilder the mind of the beholder in their aggregate; but by seizing first on its prominent outlines, marking the vol. i.—F 42 SKELETON. course of its mountains and ridges, and determining the bear- ings of the several objects according to them, we become able at length, to define not only in our own minds, but to the minds of others, the precise position of each point, or each object which may become the subject of inspection. Unfortunately the minuteness with which this portion of anatomy is described has been decried as useless, but the zealous and reasonable student ought to bear in mind—that the only rational plan of reducing a dislocated joint must de- pend upon a proper knowledge of its articular faces; that many of the great phenomena of life, as that of respiration, depend essentially upon the arrangement of the skeleton; that loco-motion is inseparably connected with it, and that, in short, it has a bearing upon almost every animal opera- tion. With these facts impressed upon him, he will be pre- pared to give the history of the natural skeleton a full and perfect attention. The primary division of the skeleton is, into the Trunk, the Head, the Superior and the Inferior Extremities. CHAPTER 1. THE TRUNK. The Trunk is constituted by the Spine, the Thorax and the Pelvis. sect. i.—the spine. The spine is placed at the posterior part of the trunk and extends from the head to the inferior opening of the' peivis. It consists of twenty-eight or nine distinct pieces of which, the upper twenty-four are true, or moveable ver' tebrse. The twenty-fifth is the sacrum, or the pelvic verte THE SPINE. 43 bra, which is fixed; and the remainder are the caudal verte- brae, or the coccyx. On the posterior face of the spine, each of the true vertebrae is seen to contribute, by a long process, to that ridge which is very readily felt beneath the skin, and from which, pro- bably, the name of spine was derived. The spine increases gradually in size from the first to the last true vertebra. The upper part of the sacrum is extended laterally much beyond the latter, afterwards the spine diminishes abruptly to the extremity of the coccyx. The spine has several cur- vatures, which are best marked in the erect position. For example, the lower part of the cervical portion is convex anteriorly, and concave behind—the thoracic partis concave in front, and convex behind—the lumbar portion is convex in front, and concave behind—the pelvic and caudal portion is concave in front and convex behind. This arrangement is the result of the different degrees of thickness in the bodies of the vertebrae, and in the fibro cartilaginous matter which unites them to each other. Wherever the cartilages are thin at their anterior margin, there is a concavity, but where they are thick at the same point, there is a convexity. There are seven vertebrae to the neck, called cervical; twelve to the thorax, called dorsal; and five to the loins, called lumbar. In reckoning the number of the vertebrse, the one next to the occiput is always the first, and so on suc- cessively to the last. Albinus, however, has departed from this rule and counts them, from below, upwards. General Characters of a Vertebra. A vertebra consists in a body, in seven processes or extre- mities, and in a hollow for lodging the spinal marrow. The body of a vertebra is at its fore part; it is somewhat cylindroid or oval, but varies considerably from these figures according to its position in the spine. The anterior part of the body is convex; but the posterior part is concave, where it contributes to the spinal canal. The superior and inferior surfaces are flat, with the exception of a ridge of hard bone 44 SKELETON, at the circumference, more elevated, and not so extended n. some bones as in others. These ridges are, in young sub- jects, epiphyses. There are many foramina, large and small, to be seen on the front and back surfaces of the bodies. They transmit arteries and veins, and some of them are used as a mean of fastening for the ligaments of the spine. On the posterior face there are two foramina larger than the others, occupied by veins coming from the interior of the ver- tebrae. These veins correspond with the diploic sinuses in the head. They have been particularly described by M. Breschet, of Paris, in a thesis presented to the School of Medicine in 1819. The processes are placed at the posterior part of the ver- tebra. Of these there are four oblique or articulating pro- cesses, which articulate with the corresponding ones of the bones, above and below ; two transverse processes, which project, one on either side, from between the oblique pro- cesses ; and one spinous process, which is placed on the mid- dle of the bone behind. The two oblique, and the transverse process on each side, come from a common base or root that arises from the lateral posterior part of the body, and pre- sent collectively a very irregular appearance. Their faces and inclinations are much modified in the several vertebra. The spinous process is also much modified in regard to size, shape, and inclination. The body and processes form the periphery of the large foramen for the spinal marrow, and, by their thickness and strength, afford an excellent protection to the latter. This foramen is of a triangular shape, presenting its base in front and its apex behind. It is always much larger than the spinal marrow, including its vessels, membranes, and the nerves that proceed from it; in which respect it differs very materially from the cavity of the cranium, where the latter is exactly filled by the brain. . At the upper part of the spinal foramen, between the body and the upper articulating or oblique process, is a groove- THE SPINE. 45 There is another groove between the lower oblique process and the body. These grooves, by the approximation of the contiguous vertebrae, are converted into perfect canals, called inter-vertebral foramina, for the transmission of the spinal nerves and blood vessels. The bodies of the vertebrae are extremely light and spongy, being covered, with the exception of their upper and lower surfaces, with a very thin lamella of bone. The processes, for the most part, have a thick and compact structure, ena- bling them to sustain conveniently the weight of the body and the action of the different muscles which are applied to them. Of the Cervical Vertebras generally. The cervical vertebrae differ among themselves, but are distinguished by certain common properties from the other bones of the spine. Their bodies and processes are small, but the spinal foramen is large, so as to admit of much mo- tion, without pressing on the spinal marrow. The fore and back parts of the body are more flattened. The upper face is concave transversely, being bounded on each side by a ridge of bone; the lower face is concave from before back- wards, and is bounded by a ridge before and behind. This arrangement permits the bodies of adjoining vertebrae to embrace each other in the dried bones, and grants great facility of motion, in the living body, by the interposition of the inter-vertebral substance. The oblique processes have their articular faces at an angle of about forty-five degrees. The superior face upwards and backwards, the inferior downwards and forwards. The spinous process is short, triangular, nearly horizontal, and bifurcated at its posterior extremity, where it terminates in two tubercles. The transverse processes are short, and perforated by a large canal for the transmission of the ver- tebral artery and vein ; they are concave above, somewhat convex below, and present two points at their external ex- tremities for the origin and insertion of muscles. 46 ski:LEI ON Of the Cervical Vertebras individually. The first cervical vertebra, commonly called the Atlas, from its supporting the head, presents the appearance of a large irregular ring, much thicker at its sides than elsewhere. It is entirely deficient in body, owing to the space allotted to that part in the other vertebrae being occupied by the pro- cessus dentatus of the second vertebra. Its oblique processes are peculiar, both in shape and posi- tion. The upper ones are concave and horizontal, their long diameters being extended from within outwards and back- wards, so as to suit the direction of the condyles of the occi- pital bone with which they articulate; the greatest depth of their concavity is therefore internal. The inferior oblique processes are smaller, slightly concave, and circular; they rest upon the shoulders of the second vertebra. At the in- ternal margin of the oblique processes a rounded tubercle is found on either side of the bone. The transverse ligament of the neck is extended between the two tubercles, and keeps the processus dentatus in its place. The short thin bridge at the fore part of the bone, is marked in front by a tubercle, and behind by an articular face which touches the processus dentatus. The bridge or section of the ring forming the posterior part of the bone, is much longer and more arched than the anterior. It also has in its centre a tubercle, occupying the position of a spinous process. At the anterior extremity of the bridge, just behind the upper oblique process, there is a groove, and sometimes a canal, made by the vertebral vessels, just before they enter the foramen magnum occipitis. The transverse processes of this vertebra are at the sides of the thick part of the ring; from their greater length, they project considerably beyond the transverse processes below and are also perforated at their bases by the vertebral vessels* which have a very winding course from them into the cra- nium. The spinal hole of the first vertebra, excluding the space THE SPINE. 47 for the processus dentatus and transverse ligament, is the largest in the spine, by which ample provision is made against injuries of the medulla spinalis, notwithstanding the great lati- tude of the rotation of this bone upon the second vertebra. A considerable vacuity is left between the upper posterior margin of the atlas and the contiguous surface of the os occi- pitis, for the ginglymoid motion of the head upon the atlas. The second vertebra of the neck is particularly remark- able for the elongation of its body above into the processus dentatus or tooth-like process. This process rises as high as the superior margin of the atlas, and almost touches the anterior margin of the foramen magnum occipitis. It pre- sents an articular face in front, where it touches the first ver- tebra. It presents also a smooth face behind, where it touches the transverse ligament. Above the latter face, on each side, is a flat surface for the origin of the moderator ligaments, and the very point above presents a small rough surface for the vertical ligament going to the margin of the foramen magnum. On each side of the tooth-like process, this bone presents its superior oblique process, as a shoulder, nearly horizontal, circular, and somewhat convex. The inferior oblique pro- cess has nothing peculiar either in its position or direction. The foramen of the transverse process is directed upwards and outwards. The interior part of the body is like that of the other vertebrae. The posterior part of the second vertebra is strong and broad. The spinous process is longer than any other except the seventh, and also larger; it is triangular, presents a ridge above and a fossa below, and is bifurcated at its extre- mity. Just behind the upper oblique process there is a very superficial notch, scarcely discernible, for the inter-vertebral foramen. The processus dentatus is the pivot or axle upon which the head revolves, and is stationary while these mo- tions are going on. The vertebr* of the neck increase gradually in the size of 48 SKELETON. their bodies from the second to the seventh, and there is sut ficient uniformity between them, with the exception of the last to render the general description applicable, though it is not difficult to observe some minute and unimportant points of difference. The spinous process of the sixth vertebra is long, and ter- minates in a sharp point. The seventh cervical looks like a dorsal vertebra, and has some peculiarities which are well marked. Its body is larger, its superior face is less concave than in the others, and its inferior face is flat. Its spinous process is the longest of all, is not bifurcated, but terminates by a rounded tubercle easily felt beneath the skin. Its transverse processes are thrown somewhat backwards, and though there is a small foramen in them, it is not large enough to receive the vertebral ves- sels. Sometimes on the side of its body, at its lower margin, is a small face, by which it partially articulates with the head of the first rib. Mr. Portal* reports, that in some rare cases he has seen only six, and in others eight cervical vertebrae, neither of which deviations have I ever met with. Of the Dorsal Vertebrae. General or common characters.—The dorsal vertebrae, amounting to twelve, being intermediate in position to those of the neck and loins, are also intermediate in size. They diminish in the transverse diameter of their bodies from the first to the third, afterwards they increase regularly in size to the last. Their bodies are more cylindroid than those of the neck. The most of them are marked laterally on the upper, and also on the lower margins, near the base of the processes with a small articular face, which receives one half of the head of a rib. The adjoining fossa of the contiguous verte- bra, receives the other half of the head of the same rib. The superior of these articular faces is larger than the inferior. * Anat. Medicale. Paris, 1803. THE SPTNE. 49 The superior oblique processes are flat, and present almost backwards ; the inferior are also flat, and present as directly forwards. The transverse processes are directed obliquely backwards; they are long, terminate in an enlarged extre- mity, which presents an articular face in front for the tubercle of the contiguous rib. The transverse processes are directed more backwards, and diminish in length as they descend. The spinal processes are long, triangular, with a broad base, and an extremity somewhat rough, swollen, and sharp- pointed, except in the upper and lower; they have a ridge above and a fossa below; are directed obliquely downwards, and overlap each other. The spinal foramen is small and round. The notch for the inter-vertebral foramen is formed principally by the ver- tebra above. Of the Dorsal Vertebrse individually.—These vertebrae, though they have many common points of resemblance, yet some of them present distinguishing peculiarities.- Of these, the first and the two or three last are the most remarkable. The first has a complete articular face on the side of its body for the head of the first rib, and a partial surface at its lower margin for the head of the second rib. Its spinous process is projecting, and not so oblique as some of the others; the flatness of its body makes it look much like a cervical vertebra. The three lower dorsal vertebrae approach in the form of their bodies to those of the loins. Frequently, hut not always, tlve tenth has the articular face for the head of the rib equi- distant from its upper and lower margins, and its transverse process so short, and inclined backwards, that the tubercle of the tenth rib does not form an articular face with it. The eleventh and twelfth vertebra have also the fossa for the heads of the ribs in their middle, at the sides of the roots of the processes, instead of a partial pit at their upper and lower margins. Their transverse processes are remarkably short, are directed almost backwards and do not touch the ribs, and have therefore no articular marks. Their spinous pro- VOL. I.—G 50 SKF.LEl ON. cess departs from the triangular shape, becomes flattened ami vertical at its sides, is not far from being horizontal, and has a tubercle at its extremity. The middle vertebra of the back have some minute points of difference among themselves, the most of which it would be useless to study. They increase, as stated, gradually in size as they descend, and their spinous processes are very near to, and overlap each other, like shingles on the roof of a house. Of the Lumbar Vertebras. Common characters.—Their number has been stated at five. Their bodies are larger than those of the other verte- bra of the spine, and are oval on the upper and lower sur- faces, with the long diameter transverse. The epiphyses at the margins of these faces, are larger and more elevated. The spinal foramen is triangular and more capacious. The inter-vertebral notches for the nerves to pass out, are much larger than elsewhere in the spine, and are formed princi- pally by the upper vertebra, though the difference is not very remarkable. The transverse processes are very long, and stand out at right angles. The articular faces of the oblique processes above are concave and vertical, being directed very much inwards, or looking towards each other; the oblique processes below are convex, and "have the same faces directed very much out- wardly. The spinous process is short, thick, horizontal, having broad, flat sides, and terminating by an oblong tubercle. Of the individual Lumbar Vertebrae.—These bones are not so well marked among themselves as the other vertebra. They may be distinguished in a single set, by the successive increase in the size of their bodies. The first, therefore, is known by its smallness, by the shortness of its transverse process, and by the deep concavity between the superior oblique processes. THE SPINE. £i The transverse and spinous processes of the three middle vertebra are rather longer than those of the others ; the third has them the longest of all. The last lumbar vertebra may be recognized by its greater size; by its body being flat, and deeper in front than behind, so as to give it somewhat of a wedge shape ; by the greater size of its spinal foramen; by the obliquity backwards of the transverse process; and by the w ide interval between the oblique processes, as well as by the lower of the latter facing almost directly forwards. Of the Pelvic Vertebrae. The Os Sacrum, the largest by much of any of the bones in the spinal column, is supposed to have obtained its name from its having been offered in sacrifice by the ancients. It forms the posterior and superior boundary of the pelvis, as well as the pedestal of the spine, and may therefore be pro- perly studied along with either of them, though its associa- tion with the spine seems more natural. In its lateral bounda- ries it is triangular, it is also regularly concave before, and very irregularly convex behind. In its forming state this bone consists of five pieces, sepa- rated by long narrow interstices filled with cartilage. It is in this condition that its pieces bear a very strong resem- blance to the true vertebra, and therefore have obtained the name of false vertebra. They are all fused into one by the progress and development of the bone, but the marks of the original separation are still apparent, particularly on its front surface. The anterior face of the sacrum presents generally a regu- lar concavity, but in some subjects it is flat. This surface is pierced on each side by four holes, which communicate with the spinal cavity and transmit the nerves of the lower extremity. Beneath each range of holes is a notch, which by the corresponding one of the coccyx, is converted into a foramen for the thirtieth spinal nerve, or for the fifth of the sacrum. These foramina diminish in size, from above down- wards, their orifices are funnel shaped, and directed obliquely $2 SKELETON outwards. Horizontal ridges of bone marking the original separation of the false vertebra, pass between the holes ot the two sides. . . The false vertebra decrease in size from above, which is manifested by the successive approach of the foramina, and horizontal lines. The first of them has almost the same vertical diameter as the last of the loins, besides its great in- crease of magnitude by the lateral extension of its base. The posterior face of the sacrum is very convex and rough, and is equally divided by its spinous processes. The pro- cesses belonging to its three upper sections or bones, are for the most part well marked, and decrease in length from the first. The fourth spinous process is divided into two tuber- cles, and the fifth is fairly separated also into two tubercles, by an angular fissure, with its base downwards and open. This fissure, it may be remarked, sometimes invades the fourth spinous process, and even the third, and in some rare cases runs the whole length of the posterior surface of the bone, leaving a gap from one end to the other. The upper margin of this surface, presents on each side an oblique pro- cess for articulating with the last lumbar vertebra. Just above the upper spinous process is a deep notch, between which, and the last lumbar vertebra, is a very large vacuity. On each side of the spinous processes are four foramina, smaller and thinner than those in front, and for the passing of nervous fibrilla from the eauda equina. At their spinous margins some small and obscure risings of bone are percep- tible, which may be considered the rudiments of the oblique processes. On the outer side of these foramina, there arc sev ral more strongly marked tubercles, from which the sacro iliac ligaments arise. After these the posterior surface of the bone slants very considerably to its lateral margin. The base of the sacrum presents in its middle an oval sur- face for articulating with the last lumbar vertebra. Between this surface and the oblique process, may be remarked the groove for the fifth lumbar nerve. The base of the sacrum continuallv thickens, from the side of the oval surface to the place of junction with the ilium. 'Ihe anterior margin of THE SPINE. ro this expansion is continuous with the linea ilio-pectinea, the posterior margin is elevated at its extremity, is a substitute for a transverse process, and is placed immediately below the transverse of the last lumbar vertebra. The point of the sacrum is truncated where it articulates with the os coccygis. The lateral face of the sacrum is thicker above than below; its upper two-thirds present an irregular, and somewhat tri- angular face for joining the ilium ; the lower third is very thin, and contributes to form the sacro sciatic notch of the pelvis. The spinal canal of the sacrum is triangular, and dimi- nishes continually to its lower extremity, where it termi- nates by a small orifice, notched behind as mentione!, and exposing the last bone of the sacrum. The foramina on the anterior and posterior surface of the bone, communicating with this canal, correspond strictly in their uses and posi- tions with the inter-vertebral foramina of other parts of the spine. The sacrum is extremely light for its size, and its texture is in a high degree spongy, but its processes and articular faces are quite as compact as they are in other parts of the spine. ^, Of the Coccyx or Caudal Vertebrae. The Os Coccygis resembles the sacrum in shape and tex- ture, and is so placed as to continue the line of the curvature of the sacrum forwards. It consists in four pieces, some- times only three, united to one another by fibro-cartilaginous matter, and corresponds with the tails of animals. These pieces in the progress of life, are not only anchylosed to- gether, but also with the sacrum, so that all the false verte- bra from the base of the sacrum to the point of the ooccyx are fused into a single bone. The upper bone of the coccyx is the largest, and is the base of this little pyramidal pile ; it is united, by its middle, to the truncated apex of the sacrum ; and its sides more- over are, in the perfect specimen, elongated several linei o4> SKELETON beyond this surface of contact. Between the upper margin of the coccyx, and the lower of the sacrum, a foramen is sometimes formed which looks like a fifth foramen on each side of the latter bone From the posterior surface of the first bone, of the perfect coccyx, a tubercle arises on either side, which is curved upwards and joins the bifurcated termination of the last spinous process of the sacrum ; be- tween the two an inter-vertebral foramen is left for the pas- sage of the fifth sacral nerve forwards. Immediately below this tubercle is a notch, made by the sixth sacral nerve or the thirtieth of the spine. The remaining bones of the coccyx are much smaller than the first, and diminish successively. The surfaces which they all present to each other are somewhat concave in the centre. The lower end of the last bone terminates in a rough point, to which a cartilage is appended. These bones are very spongy and light, their principal strength is de- rived from a ligamentous covering. To them are attached the sacro sciatic ligaments, coccygai, the levatores ani, and the glutai maximi muscles. # SECT. II.—OF THE LIGAMENTS OP THE SPINE. Ligaments of the Bodies of the Vertebras. 1. Inter-vertebral Substance.—The bodies of the true verte- bra are united by a substance blending the nature of ligament and that of cartilage, and therefore called fibro or ligamento cartilaginous matter. It occupies all the space between the contiguous bodies of the vertebra, and adheres most closely to their substance. This inter-vertebral matter increases successively in thickness, as it is placed lower down on the spine, whereby the lumbar vertebra are mutually at a much greater distance than any others. The curvatures of the spine, as stated, depend considerably upon the arrangement of this substance : between the vertebra of the neck it is thicker at its anterior margin than at the posterior; on the LIGAMENTS OF THE SPINK. 55 contrary, between the dorsal vertebra it is thinner in front. In the loins it is again much thicker in front than behind, and this feature is unusually marked between the last lumbar vertebra and the sacrum. This inter-vertebral matter is formed of concentric lamella, the texture of which is ligamentous. These lamella are more abundant anteriorly and laterally than behind. Their fibres cross in every direction, leaving between them inter- stices or cells, filled with a soft, pulpy substance. This substance is not very obvious near the circumference, but. in approaching the centre, it becomes more and more abun- dant, as the interstices are larger, until the centre seems to be constituted almost entirely by it. The pulpy mass in the centre is in a state of considerable compression, which may be proved by separating the bodies of adjoining vertebra, or by making a vertical section through them, in which case the pulpy mass will be freed from compression, and will rise up into the form of a cone. This experiment will succeed remarkably well in the loins; from which it is evident, that this mass is a soft and elastic ball, on which the bodies of the vertebra play. The pulpy matter is much more abundant in infancy than in the subsequent periods of life, it is also much softer, whiter, and more transparent. In advanced life there is a great diminution of its volume, as well as of its elasticity, which accounts in some measure for the comparative stiffness of the spine in old people. The fibrous part in them is al- ways more abundant, and is much disposed to ossify. When the trunk is kept erect for several hours in succession, it be- comes shorter, from its weight bearing upon the inter-verte- bral mass, but a short period of rest in th3 horizontal posi- tion, restores it to its original length. 2. interior Vertebral Ligament.—This ligament is placed on the front part of the spine, and extends from the second vertebra of the neck to the first bone of the sacrum, inclu- sively. It increases gradually in breadth, from its commence- ment to its termination, but is not every where of the same 5Q SKELETON thickness, for it is thin on the neck, thicker on the back, and again becomes thin in the loins ; in the latter, however, it is strengthened by an accession of fibres from the tendinous crura of the diaphragm. This ligament adheres very closely to the inter-vertebral substance, and to the projecting margins of the bodies of the vertebra, but less closely to the middle or concave parts of the latter. Its fibres do not run out its whole length, for the more superficial extend from one vertebra or intcr-vcrtebral substance, to the fourth or fifth below ; the middle ones ex- tend to the second or third below ; and the deepest seated are applied between the proximate vertebra only. In general more of the fibres arc inserted into, and arise from the fibro- cartilaginous matter than from the bones. In several parts, but particularly in the neck, small slips are sent off obliquely to the vertebra below. The lamina of this ligament leave intervals between them for the passage of blood vessels. Beneath the anterior vertebral ligament are found a great many short and insulated ligamentous fibres, extended ob- liquely from one vertebra to another just below. These fibres have different directions, and cross each other at acute angles, they adhere very closely to the fibro-cartilaginous matter, and leave interstices between themselves, through which the anterior vertebral ligament adheres to the same substance. Moreover, there are at the sides of the bodies of the vertebra, a number of short straight fibres passing from the edge of the bone above to the edge of the bone below. 3. Posterior Vertebral Ligament.—This is placed on the hind part of "the bodies of the vertebra, within the spinal canal, and extends from the cuneiform process of the occiput just beyond the foramen magnum to the os coccygis. It is more narrow and thick in the back than elsewhere. At each inter-vertebral substance it increases in breadth and adheres more closely, whereas opposite the body of a vertebra it is narrowed and more loose, by which arrangement a kind of serrated or unequal edge is formed on either side. LIGAMENTS OF THE SPINE. rn i) J This ligament is more dense and compact than the ante- rior, and presents a smooth, shining surface, resembling a tendinous expansion. Its fibres, also, do not run individually the whole length of the spine, but are in lamina, the more superficial of which have their fibres inserted into the fourth or fifth inter-vertebral substance or vertebra, below their origin. The middle lamina are inserted into the second or third below, and the deep seated into the first below. The blood vessels do not penetrate the ligament but pass by its sides into the vertebra. The superior extremity of this liga- ment going from the second vertebra to the margin of the foramen magnum, is sometimes considered as distinct. Ligaments of the Processes of the Vertebrae. I. Articulation of the Oblique Processes.—These processes are faced with cartilage, and a synovial capsule is dis- played upon them so as to shut up completely the cavity of the articulation. The capsular ligament is not uniform and fully developed, but is represented by a few irregular fibres passing from one bone to the other. 2. Articulation of the Spinous Processes.—With the ex- ception of the neck, ligamentous fibres are found to occupy the spaces between all the spinous processes, by passing from the spinous process above to the spinous process below. Muscles supply their places in the neck, and in the upper part of the back. These ligaments have much of a cellular structure above, but in their descent they become more liga- mentous and large, till in the loins they assume a very de- cided character, and have a quadrilateral shape. At the extremities of the spinous processes there is, also, a ligamentous band belonging to the dorsal and lumbar ver- tebra, and commencing at the seventh cervical to terminate on the spine of the sacrum. It is thin in the back, but on the loins it is very thick, and so blended with the tendinous ori- gins of the muscles, that it is not very distinguishable from them. The fibres of which it consists are of unequal lengths, VOL. II.—H 5b SKELETON being extended between two, three, four, or five vertebra, accordingly as the fibres are superficial or deep seated. S. Owing to the shortness of the spinous processes of the neck, an arrangement exists there called Ligamentum Nu- cha, or the Descending Ligament of Diemerbroeck. This ligament, though continuous with the one last described, may be considered for the sake of perspicuity as distinct. It be- gins therefore at the seventh cervical spine, ascends between the muscles of the opposite sides of the neck, and is inserted into the occipital protuberance. It is blended very much with the tendinous origins of muscles, and is distinguished from them with some difficulty occasionally. Its posterior margin is thick, but the anterior is continuous with a thin membranous expansion, which runs to the interval between the tubercles, at the end of the spinous processes of the cer- vical vertebra, and to the ridge of the occipital bone, lead- ing from the tubercle to the foramen magnum. The liga- mentum nucha therefore forms a complete septum between the muscles of the opposite sides of the neck, and is con- tinuous with the sheaths in which they play. In quadrupeds it is remarkably strong ; but in man, who, from the propor- tions of his head and his erect position, keeps the head nearly in equilibrium, it is comparatively feeble. 4. Articulation of the Bony Bridges of the Vertebrae.__The intervals between the vertebra, at the posterior part of the spinal canal, are filled up by the yellow ligaments, so called from their peculiar colour. These intervals exist between all the true vertebra, being bounded laterally by their oblique processes, and are very considerable in the loins, particu- larly below the last vertebra; they are not so large in the neck, and are still smaller in the back. Their shape varies considerably in the several sections of the spine. The yellow ligaments are two in number, forming a pair in each of these intervals; they approach one another behind at an angle, in a line with the spinous processes, and are separated by a small vertical fissure filled up with cellular LIGAMENTS OF THE SPINE. 59 substance. Each portion is lengthened out to the oblique process laterally, and is connected above to the anterior face of the bony bridge, whereas below it is inserted into the su- perior margin. From this arrangement, the yellow ligaments may be best seen on the side of the spinal canal. The angle which they form behind is continuous with the ligaments between the spinous processes. These yellow ligaments are smooth and shining on their anterior surfaces, but behind they are rough and unequal. Their fibres are numerous and extremely compact, their strength is therefore very great. Their elasticity is well marked and peculiar to them, and assists greatly in erecting the spine when it has been curved forwards. Bichat says, that there is but little cellular tissue between their fibres; that they are dissolved with extreme difficulty in boiling water, and resist its action to such a degree, that it is manifest they contain much less gelatine than the greater number of analo- gous organs. *-'The first pair of yellow ligaments is between the second and third cervical vertebra, and the last between the last lumbar and the sacrum; there are, consequently, twenty-three pairs in all. Particular Articulations of the Spine. 1. Articulation of Occiput with Atlas.—The Anterior Liga- ment is placed at the anterior part of the occipital foramen, and extends from it to the corresponding edge of the atlas. It is divided into two fasciculi, of which the most superficial, being somewhat rounded and narrow, descends from the middle of the root of the cuneiform process to terminate in the tubercle on the front of the atlas, and consists in parallel fibres. The second, called by Caldani membranaannuli anterioris atlan- tis, occupies and shuts up the whole space between the basilar process of the os occipitis, from which it takes its origin near the occipital foramen ; and the anterior arch of the atlas, in the superior margin of which it is lost: in it aro^ many oblique fibres, which run from within outwards. 60 SKELETON. The Posterior Ligament is placed at the back part of the: occipital foramen, and extends from it to the corresponding edge of the atlas. It is called by Caldani membrana annuli posterioris atlantis; and, arising from the w hole posterior margin of the occipital foramen between the condyles, it is extended to the upper contiguous margin of the atlas, so as to fill up completely this space. Bichat says, that it also con- sists in two lamina, the anterior of which is fibrous, and runs into the dura mater of the spine instead of into the bone; the posterior is of a much looser texture, and resembles com- mon cellular substance. A part of this membrane runs obliquely from the transverse process of the atlas to the part of the occiput just beneath the origin of rectus posticus minor. The articulating surfaces of the condyles, and the superior oblique processes of the first vertebra, are covered with car- tilage, and furnished with a synovial membrane arising from their margins. On the exterior of the synovial membrane* there are irregular ligamentous fibres going between the bones, and forming a capsule. 2. Articulation of the second Vertebra with the Occiput, and with the first.—The second vertebra has no articular surface joining the occiput, but some strong ligaments are passed between them. When the posterior vertebral liga- ment is detached at its commencement from the occipital bone, we see on each side of it, and beneath it, ligamentous fasciculi coming from the int< rnal face of the os occipitis, to be affixed to the body of the second vertebra behind. Some of these fibres come from the margin of the occipital foramen, and others from the internal face of the condyloid process.* They are joined at their external margins by a few fibres from the first vertebra, near its upper oblique process. The Ligamentum Transversale Atlantis, is placed imme- diately behind the processus dentatus, and divides the atlas • Caldani, Icon. Anat. Explicatio, vol. i. p. 255. LIGAMENTS OF THE SPINE. 61 into two unequal rings. It is larger in the middle than at the extremities, and has the latter inserted into the little tu- bercle at the internal side of the atlas, between the upper and the lower articular surfaces. It is a thick, strong fasciculus of fibres, and binds the processus dentatus so as to form for it a sort of collar, amounting to about one-fourth of a circle. The superior appendix of this ligament arises by a broad base from the internal margin of the foramen magnum, and terminates below by a narrow end in the upper margin of the transverse ligament. The inferior appendix arises from the lower edge of the transverse ligament, and is at- tached, by a somewhat converging end, into the posterior face of the body of the vertebra dentata. The surfaces of contact belonging to the processus denta- tus, and the anterior ring of the atlas, are covered with car- tilage, and have a synovial membrane, so as to form a perfect joint, called the vaginal ligament. A joint with a dis- tinct synovial membrane is, in like manner, formed between the posterior face of the processus dentatus and the anterior of the transverse ligament, where they come into contact. In front of the oblique processes joining the first and second vertebra, the anterior ligament of this articulation is met with. Its fibres arise from the inferior margin of the atlas and from its anterior tubercle, and are inserted into the base of the processus dentatus, and into the front of the body of the second vertebra. The fibres of the latter insertion are longer, and frequently distinct from the first. The posterior ligament is placed between the first and se- cond vertebra behind, and is connected to their contiguous margins so as to fill up the interval between them, and to supply the place of the yellow ligaments. It is extremely loose and thin, so as not to interfere in the movements of the vertebra, and is almost of a cellular structure. The synovial membrane of these oblique processes is unusu- ally lax, and is reflected from the margiu of the one articu- lar surface to the other. It is in contact in front with the anterior ligament, behind with the posterior and with much cellular substance, internally with the ligaments within the 62 SKELETON. spinal canal, and externally with the carotid artery. The latter obtains from it a serous covering, without which, ac- cording to Bichat, it would be bathed in the synovial fluid. The Oblique or Moderator Ligaments are two, one on either side of the tooth-like process. They may be seen most advan- tageously by cutting through the transverse ligament, and arise from the sides and summit of the processus dentatus, to be inserted into the internal margin of each occipital con- dyle. They are thick, short, and strong, and consist in parallel fibres; their lower margins have been considered as distinct ligaments by Weitbrecht, and are described by him as coming from the neck of the process. There is some cel- lular tissue at their front, in which the process revolves. The Middle Straight Ligament, (Lig. Medium Rectum,) or Occipito Dentatum, arises from the upper extremity of the odontoid process, and is inserted into the anterior margin of the occipital foramen. This ligament should not be confounded with the superior appendix of the transverse ligament, or with the beginning of the posterior vertebral ligament, as has been done by Bichat and others. The difference is well established by Caldani, as it lies deeper when viewed from the vertebral cavity than either of them ; though from the close connexion of the fibres of the ligaments among themselves, as well as with others, the mistake may readily occur. SECT. III.—DEVELOPMENT OF THE VERTEBRAL COLUMN. This column is much longer, in proportion to the limbs, at birth, than it is in adult life, and upon it depends the prin- cipal length of the individual at this period. The head is always in proportion to the length of the spine. This pre- dominance in the head and spine is, no doubt, connected with the necessity of an early development in the nervous, respi- ratory, and alimentary system, in order to maintain the life of the individual; whereas, the use of the upper and lower VERTEBRAL COLUMN. 63 extremities being called for only at a more remote period, their development is not in proportion. It is remarked, that in adult life the principal difference in the stature of indi- viduals depends upon the length of the lower extremities, the trunk, including the head, being of nearly the same length in all. This rule, however, like all others, has numerous ex- ceptions. The spinal canal and the inter-vertebral foramina are, also, proportionably more large in the foetus. The spine of the foetus is but badly suited to the purposes of standing and walking. Its spinous processes are deficient, in consequence of which, the muscles which are intended to keep it erect, have their insertion so much in the line of mo- tion, that they perform their part very imperfectly, and the spine is continually bending forwards, from the erect position. All the transverse processes are also imperfectly developed, those of the loins are particularly deficient; those of the back and neck are less deficient, as in the one case they have to form an articular surface for the ribs, and in the other to allow passage to the vertebral artery. The bodies of the vertebra are imperfectly ossified, and are separated by car- tilage from the processes. The epiphyses, or upper and lower surfaces of the bodies, are in the state of cartilage; the bodies therefore are rounded both above and below, whereby their surfaces of contact are much reduced in extent, and the line of support to the trunk rendered much less firm. When, at this age, the vertebra are macerated, their bodies present themselves as small rounded tubercles ; and very nearly one half of the whole length of the spine is made up of the cartilaginous epiphyses and the inter-vertebral cartilages. The spine, in the foetus, is almost straight, and scarcely pre- sents at all those curvatures, for which it is so remarkable in adult life. This depends upon the rounded form of the bodies of the vertebra, and the uniformity of thickness in the inter-vertebral matter at its anterior and posterior edge. 64 SKELETON SECT. IV.--ON THE USES OF THK VERTEBRAL COLUMN. The vertebral column performs three important offices in the animal economy. It affords a secure lodgement to the spinal marrow; is a line of support to the trunk, in every variety of position ; and is the centre of all its movements. In standing, the spine supports the head and sustains the weight of the trunk. In regard to the head its volume is so much more considerable in front of the foramen magnum, that, at the first view, one is inclined to admit a great prepon- derance in that direction. This impression will be corrected on observing, that the diameters of the cranium are augment- ed posteriorly, and therefore contain a proportionate quantity of brain, whereas they are smaller in front : also, that the weight of the head, in front of the foramen magnum, is dimi- nished by the number and extent of its cavities there, the most of which are empty or nearly so, as the sphenoidal, the frontal, the maxillary sinuses, and the nose. The horizontal position of the condyles of the occiput is also highly favourable to the equilibrium of the head, and to the retaining of it in that posture, without much exertion on the part of the muscles intended to keep it erect. But in the lower orders of animals the obliquity of the condyles and the great length of the face, act as a weight upon a long lever, and have a continual ten- dency to incline the head downwards, which is only partially counteracted by the largeness of the muscles and ligaments on the back of the neck. The horizontal course of the condyles, and their location near the centre of the base of the head, have always arrested the attention of natu- ralists, and established for man characters distinguishing him, from all other animals, for facility in maintaining the erect attitude. Bichat happily observes, that from this con- formation results the following peculiarities in his organiza- tion : 1. less strength in the muscles of the neck than in qua- drupeds ; 2. less projection in the occipital bone, where these muscles arc inserted ; and, 3. an imperfect development of the ligamentum nucha. The head, however, though nearly VERTEBRAL COLUMN Q5 balanced, has some preponderance in front which is mani- fested by its falling forwards, whenever we sleep in the erect position, or when the sudden suspension of life destroys the contraction of the muscles on the back of the neck. The thoracic and abdominal viscera, by being placed in front of the spine, and having no counterpoise behind, have a continued tendency to bend it. This is only resisted by the muscles which fill up the long gutter on either side of the spinous processes, and are inserted into the ribs, the spinous and the transverse processes. The lumbar vertebra and the appertaining muscles and ligaments, having an increased duty to perform, from the lowness of their position, and the variety of their movements; become the soonest affected by fatigue and bodily weakness, and therefore manifest sooner the sensation of lassitude, notwithstanding the augmented volume of the bodies and processes of the vertebra, and of the muscular masses inserted into them. The mechanical arrangement of the spine permits it to perform the motions of flexion, extension, lateral bending, circumduction, and rotation. 1. Flexion, or that posture in which the spine is bent for- wards, is the most extensive of its movements ; the general mechanism of the human body disposes us to approach sur- rounding objects in that direction, and the muscles of the abdomen, besides their intrinsic strength, act most advanta- geously in producing it; by being removed to a great dis- tance from the centre or line of motion. In this position the inter-vertebral cartilages are diminished or compressed in front, and thickened behind, the anterior vertebral ligament is in a state of relaxation, while the posterior vertebral liga- ment, and those which connect the spinous processes, are in a state of proportionate tension. 2. The motion of extension on the contrary is much more limited from several causes. The muscles which act in this •case, by arising either from the posterior face of the pelvis, or vol. i.—I 66 SKELETON from the transverse processes, and going upwards to bfe in Verted either into the ribs, the transverse or the spinous pro- cesses, are much less advantageously placed than the abdo- minal muscles, in regard to the length of the lever which they employ. Moreover, a mechanical obstruction is opposed to this motion by the spinous processes of the back and neck, being very near to, and overlapping each other. The abdomi- nal muscles also afford a strong resistance to its being carried beyond a certain point, as any one may assure himself of, by the tension communicated to these muscles from placing a large billet of wood under the loin of a subject; and, when they are cut through transversely, the immediate conse- quence is, a great increase in the posterior flexion of the spine, through the agency of the lower dorsal and the lum- bar vertebra. The anterior vertebral and the inter-vertebral ligaments, likewise, oppose the extension of the spine, much more than the elastic and the inter-spinal ligaments do its flexion. 3. The lateral curvature of the spine is a motion of consi- derable extent, and is obtained both by the very advantage- ous position of the muscles on the side of the trunk and neck, and by the little mechanical resistance to it from the shape and arrangement of the parts concerned* A principal impe- diment to this motion being carried beyond a certain point, is presented by the ribs striking against each other. The transverse processes of all the vertebra are so far apart, particularly in the loins, that they scarcely deserve to enter into the estimate of resistances. As the muscles of the one side produce the lateral curvature, so their resistance on the other limit it to a certain extent, as may be readily ascer- tained by cutting them through. 4. The circumduction of the spine is that motion in which the trunk is caused to describe a cone, the base of which is above, and the apex below. It is performed on the lower dorsal and the lumbar vertebra, and is a succession of the movements already described. VERTEBRAL COLUMN. 67 5. The rotation of the spine is a very limited motion. It is performed almost entirely on the lower dorsal and the upper lumbar vertebra, and presents in its analysis a series of minute and oblique slidings of the body of one vertebra upon another, the pivot being the oblique processes. The action occurs by the lateral yielding of the inter-vertebral substance, it must therefore be almost inconceivably small in any individual substance, particularly when the latter has been hardened and rendered more fibrous by old age. In the very young subject it is more appreciable. Of the Motions peculiar to each Class of Vertebrae. 1. The cervical vertebra, as a whole, enjoy a considera- ble share of flexion, extension, lateral inclination : and of cir- cumduction, as the result of the other motions. Their rota- tion, or the oblique sliding of the one vertebra upon the other, is very limited. The apparent facility with which they are twisted upon each other, when the face is turned to the shoulders alternately, is almost wholly the motion of the first vertebra upon the second, the participation of the other vertebra being very inconsiderable. The possibility of the dislocation of these vertebra, with the exception of the first, is very stoutly denied by authorities of the first standing in anatomy, on the score that too great a resistance to this acci- dent is afforded by the inter-vertebral and yellow ligaments, by the inter-spinal and inter-transverse muscles, by the inter- locking of the bodies of the vertebra through their reciprocal concavities and convexities, and by the shape and extent of their oblique processes. Nevertheless, it is probable that this rule is more true in general, than in particular instances. Some years ago, I met with a case in which there was every reason to believe that a partial displacement or dislocation had occurred about the fourth vertebra, in a boy of eight or ten years. It arose from his struggling to extricate himself from the grasp of a schoolmate, who held him near the ground by the back of the head, with the spine bent forwards. This position, it is evident, was calculated to lift the oblique 66 SKELETON processes of the vertebra over each other; and an oblique force applied at the same time consummated the accident, by twirling a lower oblique process over the upper margin, and in front of the one with which it was articulated below. The displacement was manifested by inability to move the neck; by a permanent inclination and turn of the head to the side opposed to the injured one; and by an inequality in the range of the anterior points of the transverse processes of the side affected. I succeeded in replacing the bone by lifting its dislocated side over the lower oblique process, communicating at the same moment a rotatory motion, the reverse of that by which the accident had happened. In an instant, the patient was re- lieved ; from extreme pain, fixed deformity, and inability to move the neck, he performed with freedom all the motions natural to the part. The principal motions of the head upon the first vertebra are those of flexion and extension; the power of the con- dyles to slide from one side to the other in the cavities formed in the atlas, is excessively restricted, both by the shape of the proximate articular surfaces, and by the ar- rangement of the ligaments; this motion is, in fact, so incon- siderable as scarcely to deserve notice. Even flexion and ex- tension appear greater than they actually are, in consequence of the lower vertebra concurring in these motions most com- monly. When simply the head is flexed upon the atlas, while the other vertebra are kept erect, the chin approaches the ster- num, and the skin of the neck is thrown into folds ; but when all the bones are flexed, the head is thrown forwards and the skin is kept tense. The flexion of the head upon the atlas is restricted by the ligamentum nucha, and by the ligament pass- ing from the posterior margin of the occipital foramen to the posterior bridge of the atlas. The extension of the head is restricted by the vertical, moderator, anterior and posterior vertebral ligaments. The motion of the atlas upon the axis is limited strictly to rotation. The confinement of the processus dentatus by the transverse ligament behind, and by the anterior bridge •jf the first vertebra in front, prevents thoroughly both flexion VERTEBRAL COLUMN. 69 and extension. The horizontal direction and the flatness of the corresponding articular faces of these two vertebra, also prevent any lateral inclination. In compensation for these restrictions, the rotatory motion is enjoyed to great ex- tent, and is amply provided for, by the extreme looseness and thinness of the capsular ligament of the oblique processes. In this motion the arch of the atlas and the transverse ligament rotate on the tooth-like process to the right and left alternately; at the same time the inferior oblique process of the atlas is slid either forwards or backwards, according to the general direction upon the upper oblique process of the dentata. This movement is checked, at a certain point, by the moderator ligaments which, by the close connexion of the head and first vertebra, answer the same purpose as if they were in- serted into the latter. It is also checked by the capsular liga- ment, notwithstanding the general laxity of the latter. But still it is not difficult for it to exceed its natural bounds, and for the oblique process of the atlas to pass completely beyond the margin of that of the dentata, and in returning to lock against it. This in fact happens, in the great majority of instances, where violence from falls, and so on, has been ap- plied to the body, and result in injury to the neck particularly; and when, in the abrupt turning of the head, produced by the action of the muscles, the individual finds himself incapable of bringing it back. This articulation is unquestionably less protected, and more exposed to accident, than any other in the spine; and, as just stated, is therefore supposed by some to be the only one in the neck admitting of luxation. Most frequently in this luxation, when it is produced by external violence, death is the immediate result, from the spinal marrow being pressed upon and disorganized above the origin of the phrenic nerve. The seat of the principle of respiration is in the medulla oblongata, and its agents are the phrenic and the intercostal nerves, the communication with which being thus cut off; respiration, and consequently circulation, stop immediately. Bichat thinks, that when death is thus suddenly produced, the processus dentatus, rup- turing its own ligaments connecting it to the occiput, slides 70 SKELETON. by the falling of the head forwards, beneath the transverse ligament, and presses upon the spinal marrow. On the con- trary, when it is a simple displacement of the oblique pro- cesses, as the odontoid process remains within its boundaries, and its ligaments are only stretched, there is no danger of death. Fatal accidents have happened to this articulation, by holding an infant from the ground, by the two hands applied to the head, from his struggles to disengage himself. A posture-maker is said to have died on the spot, from commu- nicating a rotatory motion to his trunk, while its weight was sustained by inverting his head, and making the latter the base of support. When the vertebra are displaced in such persons, as well as in those hung by the neck, it is supposed that this sliding of the processus dentatus from beneath the transverse ligament takes place; as, by experiments on the dead body, it is found that such displacement occurs much more readily than the rupture of the transverse ligament. 2. The Dorsal Vertebra are capable of but very little motion in any direction. The rigidity and length of the sternum prevent them from flexion, the overlapping and obli- quity of their spinous processes prevent them from extension, and the ribs prevent them from lateral inclination. It is, however, to be observed, that as those obstacles are diminished successively in the five lower dorsal vertebra, consequently they become more and more capable of motion upon each other. Luxation among them, at any point, is thought to be impossible, from the strength of their ligamentous attach- ments, and from the arrangement of their articular faces. 3. The Lumbar Vertebra move with great comparative freedom upon one another, admitting as stated, of flexion, ex- tension, and lateral inclination. Below, however, they arc much more restrained than they are above ; hence it results, that the principal seat of the motions of the trunk upon the • appropriated to the articulation with the sacrum, and to the origin of some of the muscles of the back. Immediately posterior to the sciatic notch is this sacral surface, somewhat triangular, but irregularly so, and extending from the iliac fossa to the posterior inferior spine. Behind the sacral sur- face is another twice as large, strongly marked by its rough- ness, and elevated into a vertical ridge at its middle. An- terior to this ridge arise many of the ligamentous fibres fastening the ilium to the sacrum ; but posterior to it is the surface of origin to the multifidus spina, and the sacro-lum- balis muscles. Os Pubis.—This bone constitutes the fore part of the inno- minatum, and is much the smallest of the three. It is com- posed by a body and two large branches from it, one running downwards to join the ischium, and the other backwards and upwards to join the ilium. The body of the pubes is joined to its fellow on the opposite side by a flat surface called the symphysis, which is eighteen or twenty lines in its long diameter. The superior part of the body also presents a flat surface, called its horizontal portion, which is bounded outwardly by a spinous process about an inch from the symphysis. The horizontal portion and the symphysis form a right angle. From the exterior face of the spine two ridges, proceed outwardly ; the poste- rior is the crista ; it is sharp, elevated, and makes the ante- rior half of the linea ilio-pectinea ; the anterior ridge is lower down, increases in its elevation as it goes along, is rounded, and runs nearly horizontally to terminate in the anterior upper margin of the acetabulum. Between the two ridges is a superficial triangular concavity occupied by the origin of the pectineus muscle. The base of the triangle is bounded by the boss formed at the junction of the pubes and ilium; and it is exactly over this part that the femoral vessels pass ; its apex is the spine of the pubes. The extremity of the upper branch of the pubes is triangular, and much en- larged where it contributes to the acetabulum. The inferior branch of the pubes, technically called its VOL. I.—K n SKELETON. ramus is a flattened process about an inch in length, and as mentioned, descends to join the ischium. Its exterior is plain, and has no mark deserving of attention, but the internal face near the anterior margin, is concave for attaching the cms oi the penis or of the clitoris. The body of the pubes in front is concave, and gives ori- gin to the adductor longus and brevis muscles ; behind it is only sufficiently concave to participate in the general con- cavity of the pelvis. Os Ischium.—This bone forms the posterior inferior por- tion of the os innominatum, and is the next in size to the ilium. It is of a triangular form, and has the anterior ex- tremity bent upwards to join with the pubes. The latter part is its cms, and the remainder is its body. The body of the ischium is a triangular pyramid, the in- ternal side of which is smooth and uniform, but the posterior and the external sides arc very unequal. The internal side is broad above and narrow below ; at the middle of its pos- terior margin is the spinous process, a projection of consi- derable magnitude and sharp pointed, for attaching the lesser sacro-sciatic ligament. Immediately below the spinous pro- cess is a smooth concave surface forming a trochlea, over which the obturator internus muscle plays. Below this troch- lea, and forming the most inferior internal margin of the bone, is a long ridge somewhat more elevated behind, into which the great sacro-sciatic ligament is inserted. The in- ternal face of the ischium, though technically called its plane, departs from the perfect regularity implied in that name, by participating in the general concavity of the pelvis. The posterior face of the ischium is swollen out above into a rounded surface, for strengthening the posterior parietes of the acetabulum. This swell is bounded below by a trans- verse depression or fossa, immediately below which, is the tuberosity of the ischium, a large rough surface extending from the fossa to the beginning of the crus. This rough sur- face is subdivided into four, two above, and two below. The •ne above, which is external, and nearest to the acetabulum. OSSA INNOMINATA. 75 gives origin to the scmi-membranosus muscle; the other, which is internal, gives origin to the semi-tendinosus, and to the long head of the biceps flexor cruris. Of the two flat surfaces below the one which borders on the ridge for the in- sertion of the great sacro-sciatic ligament, is the part on which we sit, and the last surface, which is exterior again to this, gives origin to a part of the adductor magnus muscle. The exterior face of the ischium above, form:; the lower part of the acetabulum, and is therefore very much excavated, below this the surface is flat, and sufficiently uniform to dis- pense with a particular description. The crus of the ischium is flattened internally and exter- nally, and in the adult it is fused completely into the crus of the pubes, so that very faint marks of their primitive separa- tion are left. The anterior margin of the crus has for the origin of the crus penis and the erector penis muscle, an ex- cavation continuous with that on the crus of the pubes. In examining the general features of the Os Innominatum, it will be observed, that its outline is in some degree ex- pressed by the figure 8 : the narrowing in its centre being produced by the sciatic notch below ; and by the deep con- cavity above, between the anterior superior spinous process and the symphysis of the pubes. The regularly rounded margin of the ilium above, and of the ischium bejow, contri- bute to the resemblance, but the angle of the pubes interrupts it. The narrowest part of the bone, or its neck, is between the tip of the sciatic notch and the fossa below the anterior inferior spinous process. It will also be remarked, that the posterior margin of the sciatic notch is formed by the ilium, and the anterior by the ischium. The Acetabulum, or the Cotyloid Cavity, is placed imme- diately on the outside of the neck of the os innominatum. In infancy one-fifth of it is seen to be made by the pubes, two- fifths by the ilium, and two-fifths by the ischium. It is a very deep hemispherical depression, having a sharp elevated margin all around, particularly at its superior part. The inferior margin, amounting to one-eighth of the whole cir- ;6 SKELETON. cumfcremr, is comparathcly shallow, and is, indeed, con- verted into a notch sunk much below the general surface ol the brim. The greater part of the acetabulum is smooth, and incrusted with cartilage wherever the head of the os fe- moris is applied to the support of the trunk, but the very bot- tom with the intervening surface continuous with the notch, amounting to rather more than one-fourth of the whole cavity, is rough, sunk below the general concavity, and is occupied by a soft vascular fat. In the fore part of the innominatum a large deficiency called the Foramen Thyroideum, exists between the pubes and ischium. In the male subject it is triangular, with the an- gles rounded, but in the female it is rather oval. Leading from the plane of the ischium is a groove, which goes along the superior end of the foramen, and appears externally un- der the anterior ridge of the pubes. It conducts the obtura- tor vessels and nerve to the inner side of the thigh. The texture of the os innominatum is cellular internally, with a condensed lamella externally. It is of very various thickness. The ilium in its centre has the external and in- ternal sides so near one another, that in most, adults the light will shine through it. A large foramen is seen on the venter of the ilium, and another on its dorsum, for the trans- mission of nutritious arteries. There are several others smaller, at various points of the os innominatum, for the same purpose, and for the adhesion of ligamentous fibres. SECT. VI.—OF THE PELVIS GENRALLY. The sacrum and coccyx behind, and the ossa innominata at the sides and in front, constitute, as observed, the whole cavity called Pelvis. Its position is such, that in the adult it divides the whole length of the body into two parts nearly equal, the head and trunk forming one part, and the lower extremities the other. Generally the former are somewhat the longest, but in cases of unusual corporeal stature, the ex- cess depends upon an undue length of the inferior extremi- ties. On the contrary in persons of little height, the latter THE PELVIS. 77 have not been developed in proportion to the trunk of the body. The pelvis, as a whole, is a conoidal cavity having its base upwards, and the summit below. Its internal surface forms an irregular floor, on which the viscera of the abdo- men are sustained in the erect position, and its external sur- face by projecting considerably at various places, establishes very favourable points for the origin of muscles. The internal surface of the pelvis is divided by the projec- tion of the anterior margin of the base of the sacrum, and by the linea ilio-pectinea, into two cavities, the upper one is the great pelvis, and the lower one, the little pelvis. The great pelvis is the base of the cone, and presents at its ante- rior part a large deficiency, which is supplied in the fresh subject by the abdominal muscles. The little pelvis is a complete bony canal, much deeper behind and at the sides, than in front Its depth behind is formed by the whole length of the sacrum and coccyx; at the sides by the bodies of the ischia and a small part of the ilia; and in front only by the length of the bodies of the pubes. The upper orifice of the lesser pelvis is called its superior strait, it is somewhat oval and looks obliquely forwards and upwards. Its axis may be indicated by a line drawn from the extremity of the coccyx to a point an inch or thereabouts below the umbilicus. The inferior orifice of the lesser pelvis is called the inferior strait. Its margins in the naked skele- ton are very unequal, for it presents three very deep notches, two laterally and one in front. The first are formed by the external margins of the sacrum and coccyx contributing to deepen the sciatic notch, which already is formed in each os innominatum. The third one is formed by the convergence of the rami of the pubes and ischia of the opposite sides, and constitutes the arch of the pelvis of authors, sometimes called the arch of the pubes. The axis of the lower strait, it is clear, must have a very different direction from the axis of the su- perior, and is indicated by a line drawn from the lower part of the first bone of the sacrum, through the centre of this opening. The cavity of the lesser pelvis is increased consi- 78 SKELETON. derably behind, by the curvature of the sacrum ; this, how- ever, is not uniform, as the sacrum is much more curved as well as longer in some individuals than in others. The planes of the ischia are not parallel with one another, but converge slightly from above, in consequence of which the transverse diameter of the lower strait is rather smaller than the transverse diameter of the superior strait. Difference of the Pelvis in the Male and Female. There are several well marked peculiarities in the pelvis of either sex. The ossa ilia are larger, less concave, and more horizon- tal in the female. The superior strait is also larger, and more round ; its transverse diameter always exceeds the antero-posterior, whereas the latter, in the male, frequently is found the longest. The lesser pelvis is also more capa- cious in women. The crura of the pubes and ischia, are not so long as in men, but they diverge more and join at the under part of the symphysis pubis by a large, regularly rounded arch, whereas in men, the arch, as it is called, is merely an acute angle. The os sacrum in women is shorter, more concave, and is also broader in proportion to its length. The spaces be- tween its foramina in front are very small, forming a sort of ridges, which give to the bone the appearance of having been compressed in its length. The distance between the upper and lower straits, or, in other words, the depth of the small pelvis in women, is not so great as in men; this arises from a comparative shortness in the bodies of the pubes, of the ischia; and of the sacrum as mentioned. The cartilaginous joining of the pubes is thicker in women. The diameters of the inferior strait, like those of the superior are longer in females. Accoucheurs have attached much importance to the direc- tion and length of the diameters of the small pelvis in well formed women. At an average they are as follow. The superior strait presents three diameters : The first or an- THE PELVIS. 79 tcro-postcrior extends from the upper extremity of the sym- physis pubis, to the middle of the projection of the sacrum at its superior margin, and measures four inches : The second diameter or the transverse crosses the first at right angles, and extends from the middle of one side of the strait to the corresponding point on the other, it measures five inches : The oblique diameter extends from the sacro iliac junction of one side to the linea ilio-pectinea over the aceta- bulum of the other, and measures four inches and a half. At the inferior strait, the antero-posterior diameter is drawn from the lower part of the symphysis pubis to the lower end of the sacrum, and measures five inches. As the coccyx, in child-bearing women, is moveable, its projection forwards is not taken into the account, because it recedes by the pressure of the child's head, and does not resist its passage; in some cases, however, it is unfortunately fused into the sacrum and therefore perfectly rigid, which will diminish this diameter at least an inch. The transverse diameter of the inferior strait is drawn from the middle of the internal margin of the tuberosity of one ischium, to the corresponding point on the other, and measures four inches. The depth of the little pelvis in the female, at the symphy- sis pubis, is an inch and a half; at the posterior part four inches, or five if we include the coccyx; and at the side, three inches and a half. There are many other details connected with the measurements of the pelvis, which are mentioned by systematic writers on midwifery. SECT. VII.—DEVELOPMENT OF THE PELVIS. Three points of ossification are observable in the os inno- minatum of the early foetus; one is at the superior part of the ilium, another is at the tuberosity of the ischium, and the third is at the angle of the pubes. The radii of ossifica- tion from these centres, have extended themselves consider- ably at birth, so as to sketch out the forms of the bones to which they respectively belong. But these bones arc sepa- 30 SKELETON rated from one another by cartilage, and do not coalesce till years afterwards. The union or fusion of the ilium and pubes then occurs at the ilio-pcctineal eminence, over the acetabulum, and partly in this cavity : the ilium and ischium join in the acetabulum principally, and the ischium and pubes unite by their respective crura at the middle of the internal side of the foramen ovale. All the points of the os innomi- natum, most remote from the primitive centres of ossification, are cartilaginous at birth, as, for example, the crest, the spinous processes, the tuberosity, and even the component parts of the acetabulum. The latter cavity has then a tri- angular shape, and from its very flexible and yielding con- dition, is incapable of affording a strong point of support to the trunk in the erect position. At birth the middle parts of the os sacrum, which are em- ployed in protecting the spinal marrow, are more advanced in their ossification than its lateral parts. The five pieces which compose it, are, like the bodies of the true vertebra, of a rounded shape. The processes behind are cartilaginous. The coccyx is extremely small and scarcely presents any os- sification whatever. The pelvis of the foetus, at birth, is smaller in proportion than the superior portions of the trunk; this is one of the reasons why the abdomen is so projecting. The lesser pelvis is so small and shallow that the bladder, even in the undis- tended state, cannot be accommodated by it, but is contained principally by the abdomen. Its transverse diameter is much shorter than the others. The superior strait faces much more forwards than in the adult. SECT. VIII.—OF THE ARTICULATIONS OF THE PELVIS. The mode of junction between the sacrum and the last lumbar vertebra, is, in every respect, the same as that de- scribed for the bones of the spine generally, with the addition of a ligament, sometimes met with, called sacro-vertebral, which rises from the transverse process of the last lumbar THE PELVIS 81 vertebra, and going obliquely downwards, is inserted into the superior part of the sacrum by blending itself with the anterior fibres of the sacro-iliac junction. The Sacrum is united to the coccyx by afibro cartilaginous substance, resembling that between the bodies of the true ver- tebra, with the exception of there being less pulpy matter in its centre, and of its fibrous lamella being more uniform. The bones of the coccyx are also united with one another in the same way; in consequence of which they are very flexible till the approach of old age. The Anterior Coccygeal Ligament is placed on the fore part of the latter bone; runs its whole length, and arises from the inferior extremity of the sacrum. Its fibres are rather indistinct from their being blended with fat; on the lateral margins of the coccyx they are rather better marked. The Posterior Coccygeal Ligament, as its name implies, is placed on the back part of the coccyx. It arises from the inferior margin of the spinal canal in the sacrum, and forms a sort of membranous expansion, which passes the first bone of the coccyx and is inserted into the second. There are also a few other ligamentous fibres connecting the bones of the coccyx. The Ilio Lumbar Ligament arises from the transverse pro- cess of the last lumbar vertebra, and from its inferior oblique process, and going outwards is inserted for two inches into the crista of the ilium, just above the posterior superior spi- nous process. It is often blended with adipose matter which separates it into several fasciculi. Caldani describes it as two ligaments, making a distinction between the one part from the transverse, and the other from the oblique process. The Sacro Iliac Articulation is formed by the correspond- ing surfaces of the sacrum and ilium. Each bone is incrusted with its own cartilage, the one en the sacrum being some- VOL. I.—L $2 SKELETON. what more thick. Their surfaces are slightly rough, and between them exists a thick yellow fluid in a very small quantity, which lubricates them, and is more abundant in early life. The Ligamentum Sacro Spinosum is placed superficially on this articulation behind. It is very strong, flat. long, and perpendicular. It consists of two lamina, of which the more superficial arises from the posterior superior spinous process of the ilium, and is inserted into the fourth transverse process of the sacrum. The deep seated lamina arises from the same point, and is inserted into the third transverse process of the sacrum. Bichat describes, connected with the inferior mar- gin of this ligament, a fasciculus, which comes from the in- ferior posterior spinous process. The Sacro-Iliac Ligament is next to the articular faces of the bones. It surrounds the joint, but is particularly strong on its posterior face. It consists in an assemblage of liga- mentous fasciculi, some of which have obtained, by the wri- ters on Syndesmology, particular names, but which it would scarcely add to the student's information to designate. On the front of the joint this ligament is uniform, and consists of a plane of short, strong fibres, passing from the margin of one bone to that of the other. But, on the posterior sur- face it is much more irregular, and arises from the two first eminences near the lateral margin of the sacrum, and from that surface of the sacrum between these eminences and its articular face. From thence the sacro-iliac ligament goes to be inserted into the rough surface of the ilium, immediately behind its articular face; it fills up there a considerable space, and from its position must be extremely irregular. Its strength is so great, that in forcing the joint, the ligament does not rupture, but parts preferably from the surface of the ilium, and sometimes brings with it a lamella of bone. The bones of the pelvis are also fastened by two other very strong ligaments, the sacro-sciatic. THE PELVIS. S3 The Posterior Sacro-Sciatic is the most considerable of the two. It arises from the posterior inferior spinous process of the ilium, from the margin of the sacrum below this bone, and somewhat from its posterior surface, and from the first bone of the coccyx. It goes downwards and outwards, be- comes thicker in its middle, but narrow ; it then spreads out, and is inserted along the internal margin of the tubero- sity of the ischium. Its anterior extremity is extended along the internal face of the crus of the ischium for some distance, and has the obturator internus muscle adhering to it. Its fibres, where they converge from their origin, are separated into planes by masses of fat and by blood vessels. The Anterior Sacro-Sciatic Ligament is much smaller thai* the other, and is placed in front of it. It arises from the margin, and somewhat from the posterior surface of the sa-' crum, below the ilium, and from the lateral margin of all the bones of the coccyx. The fibres converge, and are inserted into the spinous process of the ischium, by embracing it. The fibres constituting its base have their fasciculi separated by cellular adipose matter and by vessels, and are also inters mingled with the fibres of the cocuygeus muscle, and of the posterior sacro-sciatic ligament. The twa sacro-sciatic ligaments supply, in some degree, the place of bone, and form a part of the inferior lateral parietes of the pelvis. They convert the sciatic notch into a foramen, or rather form with it two foramina; the upper and larger of which transmits the pyriformis muscle, the sciatic nerve, and blood vessels; while the lower, placed be- tween the insertion of the two ligaments, transmits the obtu- rator internus muscle, and brings the internal pudic artery into the pelvis. The Obturator Ligament is extended across the foramen thyroideum, so as to close it up, with the exception of a foramen at its upper part, for transmitting the obturator vessels and nerves. It is a thin but strong membrane, hav- ing its fasciculi of fibres passing in various directions, and a-i SKELETON. arising from the margin of the foramen. It affords orign to many of the fibres of the obturator muscles. Sometimes portions of it are defective. The Articulation of the Pubes is formed between the bodies of the two ossa pubis. It consists principally in a fibro- cartilaginous matter, which has a strong resemblance to that of the vertebra. When the bones are torn apart by bending them forwards, the fibrous arrangement becomes very appa- rent, and is seen to consist in concentric lamella, the fibres of which cross one another. Sometimes in the male, but most frequently in the female, the posterior third of the articulation is deprived of these fibres, in place of which we find, in the middle of the cartilage, a small longitudinal cavity, the surface of which is smeared with a kind of muco- sity. There is no central pulpy matter in this articulation as there is between the vertebra. On its posterior surface it frequently makes a ridge projecting into the cavity of the pelvis. From frequent observations made in our dissect- ing rooms, I have no doubt that this articulation is very much relaxed in the parturient and pregnant female, which is manifested not by the bones separating, but by their slid- ing upwards and downwards with great readiness. The sacro-iliac junction also becomes relaxed. It was upon the observation of these facts, that the celebrated but now ex- ploded Sigaultian operation was founded. The Anterior Pubic Ligament is not very distinct II lies in front of the last articulation, and consists in a few oblique and transverse fibres going from the one bone to the other. The Sub or Inter-Pubic Ligament occupies the summit of the arch of the pelvis. It is of a triangular form, about half an inch in breadth, and passes from the margin of the crus of the pubes of the one side, to a corresponding line on the other. It is remarkably strong, and is rather mote so below than above. THE PELVIS. sr, SECT. IX.--ON THE MECHANISM OF THE PELVIS. The pelvis has an important part in the several actions of standing and of locomotion; besides its usefulness in giving a support to the viscera of the abdomen, and in having attached to, and contained within it, the organs of generation. In standing, the pelvis is impelled by two opposing forces, in consequence of the attachment of the vertebral column at its hind part, and of the ossa femoris at its anterior lateral parts. The weight of the head and of the upper parts of the body, falling upon the sacrum, acts upon a lever which is represented by the distance between the acetabula and the sacro-iliac junction, and has a tendency to depress the pos- terior part of the pelvis, by rotating it upon the heads of the thigh bones. This movement is obviated by the iliacus in- ternus, psoas magnus, and some other muscles, which keep the front of the pelvis from rising up. It is also prevented by the principal weight of the trunk being in front of the spine, and therefore inclining forwards, so that the centre of gravity, in the erect position, gives a continued tendency to falls forwards instead of backwards. The wedge-like shape of the sacrum is highly favourable to the erect position ; from having its base upwards, when- ever the weight of the trunk is thrown upon it, it is driven down between the ossa innominata, and has the tightness of its articular connexion, therefore, much increased, by the position which it is intended to sustain. In illustration of the usefulness of the triangular or wedge-like shape of the sacrum, it may be observed, that it is much less so in ani- mals which are intended to go upon all-fours than in the human subject The articulation of the several bones of the pelvis with each other, is so close as not to admit of any motion between them, w ith the exception of the os coccygis, and of the relax- ation peculiar to pregnancy. The pelvis, however, has upon the spine flexion, extension, lateral inclination, and rotation : the latter being performed by a series of very slight twists 86 SKELETON of the lumbar vertebra upon each other. Like all other motions, it is much extended by the habit of it in early life. Of this I lately saw an instance, in an adult Indian, who, from infancy, had been deprived entirely of the use of the lower extremities, but who, by being seated in a large wooden bowl, with a round bottom, and having his legs drawn up in a squatting position, could, by alternate twists of the spine, along with the assistance of a short staff in each hand, move with surprising speed over a plane surface. SECT. X.—OF THE THORAX. The thorax is the upper part of the trunk, and is formed by the dorsal vertebra behind, by the sternum in front, and by the ribs with their cartilages at the intermediate spaces. It is of a conoidal figure, flattened in front, somewhat con- eave behind, and cylindrical on the sides. The interior cir- cumference corresponds with the exterior, with the exception of the posterior part, where, owing to the projection of the column of dorsal vertebra, a partial septum exists, which has a tendency to divide it into two cavities. The superior part of the cone or its summit, is much smaller than the in- ferior part or the base, and presents a very oblique cordiform foramen, much lower in front than behind, owing to the su- perior margin of the sternum being lower than the first dor- sal vertebra. The base of the thorax is a very large opening? its lateral and posterior margins formed by the ribs and their cartilages, present a convexity downwards, but in front* where the latter run up to join the sternum, a large notch is formed between the cartilages of the opposite sides, into the apex of which notch the third bone of the sternum projects. Of the Ribs. The ribs are twenty-four in number, twelve on either side. Of the latter, the upper seven, in consequence of their carti- lages joining the sternum, are called the sternal or true ribs. THE THORAX. 87 and the lower five, from their cartilages stopping short of the sternum, are called the false or asternal ribs. Cases are re- corded by several anatomists of there being eleven or thirteen ribs on a side ; the latter I have seen twice only, but never the former, and therefore suppose, that the instances of dimi- nution or of increase in the number are by no means common. In such cases the vertebra are accordingly either one more or less. In the cases which came under my notice, the last rib looked like a transverse process of unusual length, belonging to the first lumbar vertebra, and the last lumbar vertebra was entirely anomalous in its shape, being intermediate in form to a lumbar vertebra, and to the first bone of the sacrum. The superabundant vertebra constituted the thirteenth dorsal, but was like the first lumbar as it commonly exists. All of the ribs are so placed that they run very obliquely downwards and forwards from their posterior extremities. This obliquity becomes the more striking as the ribs increase successively in length. The first rib, for example, articu- lating by its posterior extremity with the first vertebra of the back, has its anterior extremity nearly on a horizontal line with the lower part of the third dorsal vertebra. The seventh rib has its anterior extremity on a horizontal line with the lower margin of the last dorsal vertebra, notwith- standing its posterior extremity articulates with the seventh vertebra. The same sort of comparison might be usefully instituted in regard to all the ribs, in which case the rule will be found closely applicable, with a slight exception of the two or three last ribs. The ribs are nearly parallel to each other in this obliquity, allowance being made for the effect which the obliquity of the sternum has in causing a greater separation of their anterior extremities from each other, than exists at their posterior extremities. Common points of resemblance between the Ribs.—Each rib is paraboloid ; presents an external and an internal sur- face ; an upper and a lower margin ; a sternal and a verte- bral extremity. The external surface of each rib is convex, while its in- as SKELETON ternal surface is concave. The former presents not far from the vertebral extremity an oblique ridge, occasioned by the insertion of the sacro-lumbalis muscle. It is precisely at this line that a curvature, somewhat abrupt, takes place which is the angle of the rib. Between the angle and the transverse process of the vertebra, each rib is rather more narrow and cylindrical than it is in advance of the angle. The superior margin of the rib is rounded, and somewhat rough, for the insertion of the intercostal muscles, while the inferior margin is brought to a thin, cutting edge. Just within, and above the latter, is a fossa beginning somewhat nearer to the spine than the angle of the rib, and ceasing about one-third of the whole length of the rib, short of its anterior extremity. It contains the intercostal vessels and nerve. From the upper margin of this fossa arises the in- ternal intercostal muscle, and from the lower the external. The anterior extremities of the ribs are thin and flattened, in the upper eight there is some increase in their breadth at this point, and in all there is an oblong pit for receiving the end of the corresponding cartilage. The vertebral extremity of the rib is its head, and presents two flat articular surfaces, separated by a ridge. This head is received into the inter- vertebral matter, and upon the articular faces of the adjoin- ing margins of the vertebra. A small depression exists upon the posterior face of the rib bordering on its head, for containing a little fatty mass. About an inch beyond the head, at the posterior under surface of the rib is a tubercle, presenting a smooth articular face, for connecting itself with the transverse process of the vertebra. Just beyond this but bordering on it, is a much smaller tubercle, notunfrequently indistinct, for the insertion of ligaments, and below it is a small pit for the lodgment of fatty matter near the joint. The space between the greater tubercle and the head of the rib is its neck, which is in contact with the antero-supei ior face of the transverse process. The most of the ribs have a very sensible twist in them by which their spinal extremity is directed upwards, and the THE THORAX. 89 sternal extremity downwards, from which it results that the whole length of the rib cannot be brought into contact with a horizontal plane. Differencesin Ribs.—Though there are many common points of resemblance among the ribs, yet there are also some well marked peculiarities. The ribs increase successively in length from the first to the seventh, inclusively; they then decrease: • the last is not only the smallest, but not unfrequently the shortest. The angles of the ribs increase in their distance from the spine, from the first to the last rib. The angle, how- ever, of the first rib, is not well marked, from its being so near its tubercle, neither is the angle of the last, from its being so near its anterior extremity. The oblique ridges constituting or marking off the angles, are placed one above the other, in the same line. This gives to the back of the thorax a tri- angular flatness, the base of which is below. The projection backwards of the angles of the ribs, along with that of the spinous processes of the vertebra, forms on each side of the latter a gutter, which is filled up by the large muscles that keep the trunk erect. This gutter is, of course, broader below7. The first rib is more circular than the others. Its head is spherical instead of presenting two articular surfaces. This rib is flat above and below; its margins are internal and external. It has no intercostal groove. About the middle the upper surface is marked by a superficial oblique fossa, made by the subclavian artery, in front of, and behind which, is a su- perficial rising, marking the insertion of the scaleni muscles. The second rib is considerably longer than the first, and has its flat surfaces obliquely upwards and downwards, so as to round off that part of the thorax. The four inferior ribs de- crease at their anterior extremities, or become somewhat ta- pering. The two last ribs do not articulate with the trans- verse processes, and consequently have no corresponding tubercles. As their heads articulate with the middle of the bodies of their respective vertebra, instead of with their margins, they present only a single and somewhat spherical VOL. I.~—M 90 SKELETON surface. The eleventh rib is marked only for a short dis- tance in its middle by the fossa, for the intercostal vessels. The twelfth rib has no mark of the kind. There is an augmentation in volume from the second to the eighth rib inclusive, afterwards they decrease. The angles of the ribs are successsively more and more obtuse. The structure of the rib is spongy, covered with a lamella of compact bone. The spongy structure predominates at the anterior extremity, for there the rib is comparatively soft. Of the Sternum. This bone constitutes the middle front part of the thorax, and, ow ing to the obliquity of the ribs, has its superior end on a horizontal line with the third vertebra of the back, while its inferior extremity is on a horizontal line with the eleventh dorsal vertebra. It is also placed in a slanting di- rection, so that its lower part recedes from the spine much further than the upper. The sternum is oblong, somewhat curved like a bow, so as to be convex in front and concave behind. It is divided in the adult into three distinct pieces; an upper, middle, and lower, which are held together by cartilage and by ligament; but not unfrequently in advanced life these pieces are all fused into one, by bony union. The first and middle parts join where the second rib is articulated, and the middle and lower where the seventh rib articulates. At these points there is a well marked transverse ridge, both anteriorly and posteriorly, and between them, on the front of the bone, there are other ridges not so strong, indicating the original separation of the bone into several other distinct pieces. The lateral margins of the sternum are somewhat elevated when the ribs articulate. The upper end of the sternum is both thicker and broader than the lower end. Where the first and second parts join, there is a narrowing of the two, the same occurs where the second and third pieces unite. THE THORAX 91 Tlie first or upper bone of the sternum has an irregular square figure; it projects somewhat above, and is slightly hollow below. These particular modifications of the first bone do not, however, prevent it from having a general con- vexity in front, and a corresponding concavity behind. It is scooped out at the superior margin, and presents a point at each end of the scoop. At the side of the latter is a concave and rounded surface for articulating with the clavicle, just below which is a rough surface, for the cartilage of the first rib. The bone diminishes much in breadth from this point, and terminates by a narrow oblong face, joining it to the second piece. At each side of this junction both pieces contribute to a fossa for the cartilage of the second rib. The second bone of the sternum is longer and narrower than the first. At its lower part it increases somewhat in breadth, and then terminates by being rounded off on either side, so that its margins converge towards each other. The sides of this piece afford complete pits for the third, fourth, fifth, and sixth ribs; the pit for the seventh is common to it and the third bone, as the pit for the second rib is common to it and the first bone. The six and seventh pits are in con- tact, the fifth is very near the sixth, the fourth is about half an inch above the fifth. On viewing the whole side of the sternum, it will be observed that the distances between the pits decrease successively from the first to the last. The third bone of the sternum, in the young adult, is fre- quently in a great degree or wholly cartilaginous; hence, the name of cartilago xyphoides or ensiformis, has been applied to it. It is thin, varies remarkably in its breadth in differ- ent individuals, and has the lower extremity sometimes turned forwards and sometimes backwards, but most fre- quently it is inclined only slightly forwards. The base of this piece presents a narrow oblong surface for articulating with the second bone, at each end of which is the half fossa for the seventh rib. The margins of the.ensiform cartilage are thin, and have the transverse muscles of the abdomen d2 SKELETON. inserted into them. Sometimes the lower cxtrcmiiy, instead of being pointed, is bifurcated. The sternum is composed of a spongy texture, enveloped by a thin layer of compact substance. Its strength depends, in a great degree, on its ligamentous covering. SECT. XI.—OF THE CARTILAGES OF THE RIBS. These are placed at the anterior extremities of all the ribs, the seven superior of which they unite to the sternum by the sychondrosis articulation. The length, breadth, and direction of these cartilages, are far from being uniform. The first costal cartilage is short; the following ones in- crease in length successively to the seventh inclusively. The cartilages of the false or abdominal decrease successively in length from the eighth to the twelfth inclusively ; the last is a mere tip to the end of the rib. The breadth of the first cartilage is considerable near the sternum ; the succeeding ones are not so large at this point. With the exception of the three first, the costal extremities of the cartilages are larger than the sternal; and they become more rounded as they advance to the latter. The cartilages, in point of mag- nitude generally, will be found in proportion to the size of the ribs which they articulate with. The sixth and seventh are joined together, spread about their middle, which gives there an increase of breadth, and permits them to touch, and sometimes to coalesce. The first cartilage goes obliquely downwards in the direc- tion of the rib which it belongs to, in order to join the ster- num. The second and the third cartilages are nearly hori- zontal, but inclining a little upw ards in their progress; the fourth, fifth, sixth, and seventh, pass successively more and more obliquely upwards to the sternum, in consequence of the increasing length of the ribs requiring them to traverse a longer space to reach this bone. From the direction of the cartilages being obliquely upwards, while that of the ribs is obliquely downwards, the angle formed near the rib at the THE THORAX. 93 base of the cartilage, where the latter begins first to turn upwards, is less obtuse in the lower cartilages than in the upper. The obliquity of these cartilages is also very mani- fest, by comparing them with the side of the sternum ; with it they form a very acute angle below, and a very obtuse one above. The cartilages of the false ribs successively decrease in length, to terminate in front by small tapering extremities. The first is united by ligaments, somewhat closely, to the last true or sternal, and is occasionally sent forwards fully to the sternum. The others are united more loosely, in such a way that the anterior extremity of the one lies against the inferior margin of that which is above. The eleventh and twelfth cartilages are generally too short to touch the ones above, they therefore are fixed principally by their connexion with the abdominal muscles. Their ribs are much more moveable than any others, and have been called floating, from that cause. There is some difference between the two extremities of the cartilages; the posterior or costal is a small, convex, unequal surface, very closely united to the anterior extremity of the corresponding rib. The other, or sternal extremity in the sternal cartilages, offers a smooth articular face, which is angular or convex, according to the shape of the cavity in the sternum with which it has to articulate. The three first abdominal, and the last sternal cartilage, make, to the lower part of the thorax, a broad and well marked margin, convex in front and concave behind. The cartilages of the ribs are, in persons of middle age, white, flexible, and very elastic. They are dissolved very slowly in boiling water, by which they, if young, are reduced to gelatine, otherwise their solubility is very imperfect. They have a structure differing, in some respects, from other cartilages; when dried, and exposed to tfie action of the at- mosphere, they are seen to consist of an immense number of small thin plates, placed end to end, and separated by deep fissures. Mr. Herissant describes these plates as interlaced •mc with another, and forming a kind of spiral, the regula- 94 SKELETON rity of which is interrupted by small cartilaginous projections, uniting the plates to each other.* These cartilages have a great disposition to ossify, which is manifested in most indi- viduals somewhat advanced in life. The ossification begins in their centre and advances to the circumference, and is always preceded by a yellowish tinge. When they are fully ossified, like the ribs they are cellular within and compact externally, and are continuous with the ribs, there being no interval; in such cases, the distinction from the sternum is generally kept up, with the exception of the first, which is fused into it. The complete ossification of the first cartilage is not uncommon; the others, though there is generally in old persons a considerable deposite of bone in them, are sel- dom fully ossified. In neither case, however, is it common to see such a perfect continuity of bone between the rib and sternum, that the junction may not be solved at one point or another by the action of boiling water ; at least after very numerous observations on this subject, I do not remember to have met with a single instance of it. SECT. XII.-*-OF THE DEVELOPMENT OF THE THORAX. In the foetus the shape of the thorax differs much from that of the adult, in the greater comparative extent of its antero- posterior diameter, and in the projection of the sternum. The state of the thoracic viscera at this period, calls for such an arrangement; as the heart and thymus gland, which are in the middle, have a considerable extent, whereas the lungs are still collapsed from the emptiness of their air cells. The ribs are but little curved at their posterior parts, the angle being by no means well established, in consequence of which, the fossa on each side of the bodies of the vertebra, in the thorax, are not so deep, neither is the fossa behind, on each side of the spinous processes so fully marked. The superior opening of the thorax is more round from the increase of the • Acad. Des Science?, an. 1748. DEVELOPMENT OF THE THORAX. 95 antero-posterior diameter. The inferior opening is extremely large, both from the elevation of the sternum and from the pressure of the abdominal viscera, of which the liver, from its great extent, is a principal agent. The vertical diameter of the thorax is small, from the ribs, particularly the lower ones, being pressed up one against the other, by the dia- phragm acted on by the abdominal viscera. The bones individually are in the following state at birth. The ribs are almost completed, the cartilages where they join the spine, being in a state nearly as perfect as at any subsequent period of life, and not by any means in the condi- tion of a cartilaginous epiphysis, as is presented in the ex- tremities of the cylindrical bones generally. These bones, as Bichat very justly observes, are destined to a function which commences immediately upon birth, and which re- quires in them as much perfection then, as they have in the adult. For respiration is different from locomotion, the lat- ter requires a species of education, which may be given gradually, whereas one respires from the beginning as he will respire always. The sternum, which is less immediately connected with breathing, and only contributes to the general solidity of the thorax by completing its circumference, is in a state almost cartilaginous, and presents only nuclei of os- sification in its several pieces. At the instant of birth, a great change is produced in the dimensions of the thorax. The lungs, from being in a col- lapsed and solid state, suddenly suffer an expansion of their cells by the introduction of air into them, and increase twice or three times in magnitude. This is accomplished by the elevation of the ribs, and the consequent increase in the transverse diameter of the thorax, it becomes a condition that for ever afterwards remains, so that the lungs even upon death, continue to have their air cells distended, and do not return to a collapsed state. The action of the diaphragm is but small in the earliest periods of life, owing to the size and pressure of the abdominal viscera against it; respiration is then principally carried on by the elevation and depression 96 SKELETON. of the ribs, and by their being rolled outwards, a motion which the flexibility of their cartilages and the looseness of their articulating surfaces favour very much. At the age of puberty the thorax experiences a remarkable augmentation. Its transverse diameter is sensibly increased, and there is a general expansion of its volume, indicative of a healthy and vigorous constitution. Should this not take place, and the sternum be projected, it is supposed to mark a disposition to consumption. The enlargement of the thorax is undoubtedly connected with the development of the organs of generation at the same time. The exercise of the latter requires greater vital powers than exist in early life, and the provision for it is manifested by the general increase of vigour and firmness in the human frame; but, it is not possible to point out in what manner the sympathy exists, which, on the development of the organs of generation, extends their influence to the bony structure of the thorax. SECT. XIII.—OF THE ARTICULATIONS OF THE THORAV Anterior articulation of Thorax. The surface of each pit in the side of the sternum is covered by a thin cartilaginous plate, to receive the corresponding cartilage of the rib, and the articulation presents an anterior and a posterior ligament, also a synovial capsule. The anterior ligament arises from the extremity of the car tilage, and going over the front of the sternum, radiates very considerably in every direction. Some of its fibres are con- tinuous with the corresponding fibres of the opposite side: others are lost in the periosteum and in the tendinous origin of the great pectoral muscle; others join the fibres of the ligament above, and of that below. The more superficial the fibres are, the longer they become; but the more deeply seated, pass only from the margin of the cartilage to the margin of the cavity in the sternum. The thick ligamentous ARTICULATIONS OF THE THORAX. 97 covering found on the front of the sternum, may be consi- dered as only the continuation of these anterior ligaments. The fibres from the two lower articulations on the opposite sides, form, by their junction, a striking triangular ligamen- tous plane, just on the lower end of the second bone of the sternum. Besides which there are several strong ligamen- tous fasciculi running in a great variety of directions. The Posterior Ligaments have a similar arrangement with the anterior, in the radiation of their fibres into the conti- guous ligaments, and in their origin from the sternal carti- lages. Altogether they form, on the posterior face of the sternum, a strong smooth covering, the fibres of which do • not run in fasiculi, but present an uniform polished membrane, and are closely interwoven with each other. - Some of these fibres are longitudinal, and of course cannot be referred to the posterior ligaments, but are independent of them. The Synovial Membrane, though its existence is admitted, is not in a very distinct state. It scarcely gives a polish to the articular surfaces, and has so little looseness in its re- flection from the one to the other, as to indicate clearly that but an inconsiderable motion is admitted of, in these joints. The synovia is in very small quantity, not abundant enough for satisfactory examination, and its character is rather in- ferred than proved. The first cartilage is continuous with the sternum, and not separated from it by any joint, except in rare instances. The second cartilage has its joint with the sternum separated into two, one above and the other below, by a ligamentous partition resembling that at the heads of the ribs. The lower articulations become successively more moveable than the upper. Besides the attachments mentioned as connecting the carti- lages of the true ribs to the sternum, there is one superadded to the seventh cartilage, called the Costo Xiphoid Ligament. It arises from the inferior margin of the seventh cartilage, near the sternum, and going obliquely downwards and in- VOL. I.—W 98 SKELETON wards, is inserted into the anterior face of the xiphoid carti- lage, and has its upper fibres running into the corresponding fibres of its fellow. It is of course placed behind the rectus abdominis muscle, and fills up, in some measure, the angle be- tween the seventh cartilage and the third bone of the sternum. At the surfaces where the sixth and seventh cartilages come into contact by their edges, also the seventh and eighth, a synovial membrane exists. A similar articulation is some- times found between the fifth and sixth, and the eighth and ninth cartilages, but not uniformly. These synovial mem- branes are covered by strong fibres. It has been already stated that the anterior extremity of each of the three first abdominal cartilages is united by liga- mentous fibres to the cartilage above. These ligaments are strong and extensive, and give great solidity to the common margin of the cartilages. The two last cartilages are, as mentioned, much smaller than the others; no ligaments pass from them, but they with their ribs are held in their positions by the intercostal and abdominal muscles. The cartilages adhere very closely to their respective ribs, which receive them into the oblong fossa, at their anterior extremities. The periosteum of the rib is continuous with the perichondrium of the cartilage, and the membrane, which is in fact one and the same, adheres very closely to the mar- gins of the articulation; it is also reinforced by some liga- mentous fibres beneath it. No motion whatever is admitted at this articulation. Posterior Atriculalions of the Thorax. As mentioned, in the account of the bones, the articulations here are double: being formed at one point between the heads of the ribs and the bodies of the vertebra with the inter-ver- tebral matter; and at the other, between the tubercles of the ribs and the transverse processes. In either case the respec- tive surfaces are covered by articular cartilages, and have a synovial membrane. The first joint is the costo-vertebral and the second the costo-transverse. ARTICULATIONS OF THE THORAX. 99 i. The Costo-Vertebral articulation presents an anterior ligament, an inter-articular ligament, and two synovial membranes. The anterior ligament is fixed, as its name expresses, in front of the joint. It arises from the margin of the head of the rib by the whole breadth of the latter, and diverging towards the spine, is fixed, by its superior fibres, into the vertebra above; by its inferior fibres, into the verte- bra below ; and, by its middle fibres, into the inter-vertebral substance. It is a thin, flat, fibrous membrane, leaving in- tervals in it for the passage of blood vessels, and may indeed be considered as a capsule to the articulation, and is frequent- ly described as such. The inter-articular ligament passes from the ridge on the head of the rib, to the corresponding line of the inter-vertebral substance. It is short and strong, and divides the articulation of the head of. the rib into two cavities, which have no communication. It is in conse- quence of the latter that there are two synovial membranes to the head of every rib which has a double articular face, but the ribs which are articulated with a single vertebra, as the first, the eleventh, and the twelfth, have not the inter- articular ligament, and only one synovial membrane. The Synovial Membranes are not very apparent, neither is the fluid abundant; the cavity is occasionally very small from the encroachment of the inter-articular ligament. An- chylosis occasionally takes place here, but it is much less frequent than in the anterior articulations of the thorax. 2. The Costo-Transverse Articulation has, in addition to the joint formed between the tubercle of the rib and the end of the transverse process, several ligamentous fasciculi which pass in varied directions. The Synovial Membrane is much more distinct than in the preceding articulation, and contains more synovia. It is more loose, and is never anchylosed except by disease. There are a few fibres around it having the semblance of a capsule. The Ligamentum Transversarium Internum, arises from the inferior margin of the transverse process, between it« 100 SKELETON. root and external extremity, and proceeding downwards and inwards, is inserted into the upper margin of the neck of the rib below. The Ligamentum Transversarium Externum, is a well marked quadrangular plane of ligamentous fibres, placed on the posterior surface of the costo-transverse articulation. It arises from the extremity of the transverse process, and going outwardly is inserted into the proximate rib just beyond its articular tubercle. The Ligamentum Cervicum Costarum or the Costo-Trans- versarium Medium, is placed between and concealed by the neck of the rib and the contiguous transverse process, and cannot be seen well without separating them, or by sawing through their length. It is a collection of fibres, somewhat irregular, resembling condensed cellular substance, and slightly red. These Posterior Articulations, all require a patient dis- section to make them out, as they are surrounded by small masses of adipose matter, have the intercostal nerves and blood vessels in contact with them before, and the muscles of the spine behind. The ligaments between the transverse processes and the ribs, are of course not found in the eleventh and twelfth, from the bones not touching there. Besides what has been described, an aponeurosis or liga- mentous membrane is extended from the transverse processes of the first and second lumbar vertebra, to the inferior mar- gin of the last rib. A ligamentous membrane is also found near the spine, and extended between the contiguous margins of the two last ribs. SECT. XIV.—OF THE MECHANISM OF THE THORAX. The thorax performs two very important functions in the animal machine, by the first it contains and protects the or- gans of circulation and respiration, by the second it assists MECHANISM OF THE THORAX. 101 materially in the function of respiration, and perhaps con- siderably in those of circulation.* The mechanism of the thorax is such, that the solidity of its materials, as well as its rounded shape, present a very efficacious defence to its viscera from the influence of blows on its outside. The effects of the latter are also materially diminished by the thickness and contraction of the several large muscles which are placed on its surface. On its back part the thick longitudinal muscles of the spine, as well as those running to the superior extremities, fill up the gutters on each side of the spinous processes, and make a fleshy pro- tuberance, divided into two by the raphe wiiich extends the length of the back over the spinous processes. In front it is less protected, owing to the sternum being immediately under the skin. Nevertheless, when blows are inflicted on this part, their effects are much diminished by the elasticity of the car- tilages of the ribs, and by the direction, obliquely down- wards, of the ribs themselves: both of which dispose the sternum to retire somewhat backwards, and to yield to the impelling force. This recession will take place more rea- dily at the moment of expiration; and when the muscles which elevate the ribs are not on their guard. In those de- liberate exertions of the strength of the thorax, exhibited by individuals lying down on their backs and sustaining a heavy weight on the sternum, the ribs are saved from injury by a different means: The arched form, itself, of the front of the thorax is of considerable service in the resistance under such circumstances; this, however, would be easily overcome, and the ribs would break, if the arch were not maintained in its elevation by the contraction of the large muscles on its sides; as the serratus major, the pectoralis major and minor, each of which by acting on the depressed anterior extremi- ties of the ribs and their cartilages has a tendency to keep them elevated. Fractures of the ribs from blows or force applied in front, are not so liable to occur in the part stricken as in the point feeling the greatest momentum, which from • A very interesting paper on this subject, has lately been presented to the French Institute, by Mr. Barry. 102 SKELETON. the semicircular form of the ribs is in or near their middle; this exhibits a true example of what the French writers call the contrc-coup. Bichat says, that the fracture by contre-coup is much more common when the individual, being struck unex- pectedly, has not had time to throw his muscles into a state of contraction, for the protection of the ribs. The lateral convexity of the thorax being greater than that in front or behind, and having the same assistance from the muscles mentioned, presents a stronger resistance when blows are inflicted directly on it. Each rib represents an arch, the summit of which is its centre, and the base its two extremities. The abutments of the base are, the sternum at one end and the spine at the other, a displacement from them is com- pletely prevented by the strength of the ligamentous attach- ments, as well as by the form of the surfaces. Under these circumstances as fracture occurs preferably to dislocation from lateral force, it is generally at the point stricken. The abdominal or false ribs, from their want of attachment to the sternum, present a very different condition. Their anterior extremities, therefore, yield readily, and are driven inwards towards the abdomen. The second function of the thorax relates to its influence on respiration by dilating and contracting, whereby the air is received into, and expelled from it. The spine is the fixed point for the motions of the ribs in respiration. In the act of dilatation the capacity of the thorax is augmented in three directions, vertically, transversely, and antero-posteriorly, or from the sternum to the spine. The vertical augmentation is wholly accomplished by the diaphragm; and, as mentioned, is much greater proportionally in the adult than in the infant, from tbe size of the abdominal viscera in the latter. The transverse augmentation is produced by the successive con- traction of the intercostal muscles, which raise the ribs up- wards. The first rib is moved inconsiderably, in consequence of its shortness and of its continuity with the sternum. The attachment of the scaleni muscles to its upper surface, serves rather to give a fixation to it, and to prevent it from being MECHANISM OF THE THORAX. 103 drawn down by the other ribs, than to produce by their con- traction an elevation of it. The first rib may, therefore, be considered as a fixed point. The first intercostal muscles contracting from it, draw up the second rib, which in its turn, becoming a fixed point for the second intercostal mus- les, they contract and draw up the third rib, and so on suc- cessively to the last. It is the obliquity of the ribs from behind, downwards and forwards, which enables this eleva- tion of them to produce an increase in the lateral diameter of the thorax; without such obliquity their elevation could not produce the effect The obliquity, however, alone could be of but little service, if the anterior extremities of'the ribs were not attached to the sternum by cartilages, having to ascend in order to reach it; for it is obvious that the angle of the cartilage and rib, during their elevation by the inter- costal muscles, has a tendency to straighten itself, and will, in doing so, increase the horizontal distance between the an- terior end of the rib and the sternum, and consequently increase the transverse diameter of the thorax. The upper ribs, from the shortness as well as direction of their carti- lages, can do little or nothing in increasing this diameter. According to some anatomists, the capacity of the thorax is also augmented by a rocking motion of the rib, in which, the two extremities being stationary, the middle is drawn upward and outward. It is not, however, very clear, that this motion exists to much extent, as the manner of the pos- terior articulations of the thorax is opposed to it. While the transverse enlargement of the thorax is going on, a simultaneous motion occurs in the sternum, and in con- sequence of the oblique direction in which the ribs run to it, it is caused, by the elevation of their bodies, to recede from the spine. But, as the ribs increase successively in length from the first to the seventh, each lower one, in its elevation from the oblique towards the horizontal line, has its anterior extremity carried proportionably farther off from the spine, hence the sternum has a combined movement resulting from its several attachments to the ribs ; one motion elevates it as a whole, another causes it to recede from the spine as a whole, 104 SKELETON. and the third causes its lower end, from the increased length of the ribs there, to be pushed further from the spine than the upper; giving it thereby a sort of motion backw ards and for- wards during respiration, and resembling that of a pendu- lum. This latter motion, however, though its existence is clear, is not very considerable, from the sternum being kept in check by the tendinous centre of the diaphragm, as one may prove by examining his own body. The enlargement of the thorax, in its antero-posterior diameter, is much more considerable at the anterior extremities of the ribs, because there they are comparatively free. In this case, the carti- lages of the ribs are bent forwards, besides being elevated. In expiration, the movements of the thorax are exactly the ■ reverse of what they are in inspiration, and all its diameters are consequently diminished ; whatever may be said of mus- cular influence in producing this change, it is much exagge- rated. It is true, that there are certain muscles which may be forced into the employ, as the abdominal and some on the back, as the long issimus dorsi and sacro-lumbalis ; but the question is, are they actually so engaged, under ordinary cir- cumstances. In observing the phenomena of natural respira- tion, when, by position, these muscles are put into a state of re- laxation, it does not appear that the process is at all impaired by their being thrown out of action. The only muscles, then, that seem to be specially appropriated for producing expira- tion, are few and small, they are the serratus inferior posti- cus, on either side of the spine. The elasticity of the cartilages, by which these bodies are enabled to return from the constrained state in which they were placed by inspiration, has also been dwelled on by Hal- ler and others. The power thus derived is certainly of some value, but has much less importance than has been attached to it. It unquestionably exists in early and middle life, but it is lost in old age, when the cartilages ossify, and therefore are deprived of their elasticity. The true and efficient cause of expiration appears to be atmospheric pressure upon the external parietes of the thorax, acting along with the natu- ral elasticity of the lungs. The lungs, it is well known, MECHANISM OF THE THORAX. 105 when in a state of repose, and removed from the thorax, are much smaller than the cavities which they fill during life. They have therefore a continual tendency, in the living state, to return to the size which is most easy to them ; and, when they are further dilated by inspiration, their disposition to subsequent contraction is still more forcible. These positions are proved conclusively, by the condition of the inferior surface ■of the diaphragm in a healthy and entire thorax; wliere this muscle, in consequence of atmospheric pressure from with- out, is driven high up into its cavity. Its contraction in inspiration drawrs it down, and the instant that the contrac- tion ceases, it is impelled upwards again. Now the same power is applied to the whole periphery of the thorax : its cavity being enlarged by the contraction of the several mus- cles appropriated to the elevation of the ribs; the moment this contraction ceases, the latter are impelled downwards. From all this it will be understood that the muscles, by crea- ting a vacuum in the lungs, cause the vacuum to be filled by the introduction of air through the trachea; and upon their ceasing to contract, the several agents mentioned cause the expulsion of the same air. It is generally believed, that the surface of the lung is every where in contact with the tho- rax; it appears however doubtful, whether there is not a space between the pleura pulmonalis and diaphragmalis, particularly at the most posterior and inferior part of the diaphragm. Certain it is, that adhesions there are much less common than in other parts of the thorax. The ligaments at the spinal extremities of the ribs, by being put on the stretch in inspiration, have also some ten- dency to throw down the ribs in expiration. In short, the contraction of the thorax may be set down as the result of the joint action of the atmosphere, the cartilages of the ribs, the ligaments, the contraction of the lungs, and the inferior serrated muscles. When the structure of the lung is so altered that its elasticity is impaired or destroyed, expiration becomes then much more difficult. vol. i.—o Jr 106 SKELETON. CHAPTER II. OF THE HEAD. The head is placed upon the upper extremity of the ver- tebral column, and consists in a considerable number of bones, which are either in pairs, or if single have the two sides symmetrical. Some of these bones form a large cavity, the cranium, for containing the brain; the others are em- ployed in the formation of the nose; of the orbit for the eye- ball ; and of the mouth. The head for the most part ovoidal, presents very striking varieties of form between different in- dividuals and different nations. It is thought by physiologists, that the moral or intellectual condition of a people, their ha- bits, climate, and food, have powerful influence in producing these diversities. The head is divided into cranium and face. SECT. I.—OF THE CRANIUM. The Cranium is composed of eight bones. The Os Frontis, the Os Occipitis, two Ossa Parietalia, two Ossa Tempora, the Os Sphenoides, and the Os Ethmoides. The Os Frontis is at the front of the cranium; the Os Occipitis is at its hind part; the Ossa Parietalia, one on each side, form its superior lateral parts; the Ossa Temporum, also one on each side, form its inferior lateral parietes ; the Os Sphenoides is in the middle of its bottom part; and the Os Ethmoides is at the fore part of the centre or body of the sphenoid bone. The cavity thus formed for the brain, has three diameters, which may be learned by sawing vertically through the middle line of one scull, and horizontally through the cavity of another. The first diameter is the longest, and extends from the lower part of the frontal bone to the protuberance on the middle of the interior surface of the os occipitis, it is commonly about six inches and a half long. The second diameter includes the space between the superior THE CRANIUM. 107 margins of the temporal bones, where they are most distant from each other; and passing over the middle of the great occipital foramen, is about four inches and three-quarters. The third diameter is taken from the centre of the large hole in the occipital bone to the centre of the suture between the parietal bones ; it is about four inches and a half. Rather more than one-third of the cavity of the cranium is placed behind the second diameter, and it diminishes somewhat ab- ruptly ; but in front of this diameter the cavity is finished more gradually. When the face is separated from the cranium, the exterior surface of the latter, excepting its base, represents tolerably accurately the form and proportions of its cavity ; allow- ance being made for the large sinuses in the lower part of the frontal bone, and for the thinness of the upper parts of the temporal bones. The diameters mentioned can only re- present what most frequently happens, for daily observa- tion proves remarkable departures from them. Sometimes the transverse diameter is increased at the expense of the longest, which gives to the head a flatness before and behind. On other occasions the vertical diameter is increased, where- by the head receives a conical form. In many individuals the first diameter is increased, which makes the two sides of the cranium more parallel and flat than usual. The elonga- tion of the transverse diameter is the most common, and that of the vertical the least so. The capacity of the cranium is much the same in adult individuals of the same sex, from which it may be inferred that the excess of one diameter is obtained generally at the expense of the other. The male cranium is more capacious and thick than the female. The female sex is less liable to variations in these propor- tionate diameters than the male. Stature has but little influ- ence on the capaciousness of the cranium, as giants and dwarfs have it of the same size; hence the former seem to have very small heads, while the latter appear to have very large ones, the eye being deceived by the relative magnitude ot their bodies. . The fact seems to be now well ascertained, that continued 108 SKELETON. pressure, or rather resistance in a fixed direction, made upon the cranium of a growing infant will change its natural form. Peculiar ideas of beauty have induced certain tribes of sa- vages to adopt this barbarous and unnatural practice. The late Professor Wistar* showed to his class in 1796, a Choc- tawr Indian having this peculiarity ; and a tribe now existing near the sources of the Missouri, continues the practice of flattening both the occiput and the os frontis. In the Wistar Museum we have ten headsf of Peruvian Indians, brought from the Pacific Ocean, nine of which bear the strongest evidence of having been flattened by pres- sure, on the os frontis and on the os occipitis. The possi- bility of effecting such a change in the form of the cranium has been strongly contested, and Bichat, who admits it, ac- knowledges that he was unable to produce like modifications in puppies, kittens, and India pigs. The singular change, however, which is wrought upon the feet of Chinese ladies,. strongly corroborates the opinion of the head being also sus- ceptible of artificial modifications in its form. SECT. II.—OF THE INDIVIDUAL BONES OF THE CRANIUM- 1. Frontal Bone, (Os Frontis.) The frontal bone forms the whole anterior, and a portion of the superior, lateral and inferior parietes of the cranium. It is symmetrical, and, occasionally, is completely divided into two bones by the continuation of the suture between the parietal bones. Its external face is convex, and the internal concave. On the former may be observed a line, or slightly raised ridge, running on the middle of the bone from above downwards, which is expressive of the original separation between its two halves. The front surface of the bone is terminated on * System of Anat. 3 Edit. vol. i p. 73. 1824. t Presented by Dt. James Corneck, U. S. Navy, to Dr. Physick. THE CRANIUM, 109 either side below by the orbitary ridge, a sharp and arched elevation forming the upper anterior boundary to the orbit of the eye. This ridge terminates outwardly by the external angular process, and inwardly, by the internal angular process. Just above the internal half of the orbitary ridge the bone is raised, by the separation of its tables, into the superciliary or nasal protuberance or boss. Between the internal angular processes a broad serrated surface exists, by which the frontal bone is united to the nasal bones, and to the nasal processes of the superior maxillary bones. The centre of this surface is elevated into the nasal spine, which serves as an abutment to the nasal bones and resists any force which might tend to drive them inwardly. On its exterior lateral surface, behind the external angular process, the frontal bone presents a concavity, bounded above by a well marked semicircular ridge, and intended for the lodgement of a part of the temporal muscle. On each side of the front part of the bone a prominence exists, most fre- quently better marked in infancy than in advanced life, and called by the French the frontal protuberance or boss. Proceeding backwards from the inferior part of the bone are the two orbitar processes, concave below and convex above. They are much thinner than other parts of the bone, and are separated by an oblong opening which receives the ethmoidal bone. A depressian, large enough to receive the end of a finger, is at the exterior anterior part of the orbitav process, being protected by the external angular process; this depression contains the lachrymal gland. Half an inch above the lower margin of the internal angular process, a much smaller depression exists, occasioned by the tendon of the superior oblique muscle where it plays upon its trochlea. In the orbitar ridge, just without the latter depression, is a foramen or notch, for the passage of the frontal artery and nerve. The internal margins of the orbitar processes are broad and cellular, where they join the ethmoid bone, and at their fore part is seen a large opening on each side leading into 110 SKELETON. the frontal sinus. These margins, in common with the ethmoid bone, form two foramina, one anterior, another posterior, and called internal orbitary ; the first transmits the internal nasal branch of the ophthalmic nerve and the an- terior ethmoidal artery and vein, the latter transmits the pos- terior ethmoidal artery and vein. Externally and behind, the orbitar process presents a broad triangular serrated surface for articulating with the sphenoid bone. The interior or cerebral face of the os frontis is strongly marked by depressions corresponding with the convolutions of the brain. A vertical ridge below, becoming more ele- vated as it approaches the ethmoidal bone, separates its two sides. This ridge, extending about one-half the length of the bone, terminates above in a superficial fossa, made by the longitudinal sinus; and, at its lower extremity is the fora- men coecum, common to it and the ethmoid bone, which is occupied by a process from the falx of the dura mater. It also affords passage to some very small veins, which go from the nostrils to the commencement of the longitudinal sinus.* The frontal sinuses consist each in one or more large cells, placed beneath the nasal protuberances. There is very great variety in their magnitude and extent; sometimes they pro- ceed as far outwardly as the external angular process, and backwards for half an inch into the orbitar plates. In a few instances in the adult they do not exist, but the cases are very uncommon. The cells of the opposite sides have a complete partition. They communicate with the cavity of the nose through the anterior ethmoidal cells. With the exception of the inferior part, where the processes and sinuses exist, the os frontis is of a very uniform thick- ness, and the diploic or cellular structure is found constantly between its external and internal surfaces. This bone is united to the parietal, ethmoidal, and sphe- noidal, of the cranium ; and to several bones of the face. • Portal, Anat. Medicals THE CRANIUM. Ill 2. Parietal Bones, (Ossa Parietalia.) These bones, it has been stated, form the superior and lateral parts of the middle of the cranium. They are qua- drilateral, convex externally and concave internally. Their external and internal tables are uniformly separated by a diploic structure, which, from being more abundant at the superior part of the bones, occasions there an increased thickness. The external surface of the parietal bone is raised about its middle into the parietal protuberance. Just below this protuberance is an arched, rough, broad, but slightly elevated ridge, marking the origin of the temporal fascia and muscle, and continuous with the ridge on the side of the frontal bone. The internal surface of the bone is marked by the convolu- tions of the brain ; there are also a number of furrows upon it having an arborescent arrangement, and produced by the ramifications of the middle artery of the dura mater. These furrows all proceed from one or two large ones at the ante- rior inferior part of the bone; not unfrequently at the latter point these furrows are converted into perfect tubes, by the deposition of bone all around the arteries. The internal face of the parietal bone also presents an imperfect fossa at its superior margin, which is completed by the approximation of its fellow, and accommodates the longitudinal sinus. At the inferior posterior corner of the bone there is likewise a fossa made by the lateral sinus. The superior, posterior, and anterior margins of the parie- tal bone, are regularly serrated, and nearly straight. The inferior margin is concave, presenting a thin, beveled, radi- ated surface before, for articulating with the squamous por- tion of the temporal bone : behind this concavity, the angle of the bone is truncated and serrated, for articulating with the angular portion of the os temporis. The anterior infe- rior angle is the most remarkable, from its being elongated so as to join the sphenoid bone in the temporal fossa. 112 SKELETON A foramen called parietal is found at the superior margin of this bone, nearer to its posterior than to the anterior edge; it transmits an artery between the integuments and dura mater, and also a vein from the foramen to the longitudinal sinus. M. Portal says, that in some protracted headaches this vein swells considerably ; and that he has seen much good in such cases, arise from the application of leeches to the part: he has also seen, in a child, its tumefaction the precur- sor of the paroxysms of epilepsy. The parietal bone articulates with its fellow, with the fron- tal, the sphenoid, the temporal and the occipital bones. 3. Occipital Bone, (Os Occipitis.) This bone is quadrilateral, resembling a trapezium. It is convex externally, concave internally ; but both of these sur- faces are much modified by ridges and processes. Its thick- ness is also very unequal, from the same cause; though like the other bones it has two tables, with an intermediate diploe. It is so placed as to form a considerable share of the poste- rior and inferior parietes of the cranium. The foramen magnum is placed in the lower section of this bone, and constitutes a very conspicuous feature in it. This hole is oval, the long diameter extending from before backwards. Its anterior inferior margin, on either side, is furnished with a condyle, for articulating with the first ver- tebra of the neck. These condyles are long eminences tipped writh cartilage, which approach before but recede behind; their internal margins are deeper than their external. The condition of their articular surfaces is therefore such, that they admit flexion and extension of the head, but not rotation. The anterior edge of the foramen is thicker than the poste- rior. This foramen transmits the spinal marrow, the ver- tebral arteries and veins, and the spinal accessory nerves. The external surface of the occiput presents, half way be- THE CRANIUM. 113 tween the foramen magnum and the upper angle of the bone, the occipital protuberance, from the lower part of which a small ridge is extended in the middle line to the foramen. Into the ridge is inserted the ligamentum nuchse. From either side of the protuberance an arched ridge is extended to the lateral angle of the bone. It is the superior semicircu- lar ridge or line, from which arise the occipito frontalis and the trapezius muscles, and into it is inserted the sterno cleido mastoideus. Below this about an inch is the inferior semicircular ridge, more protuberant, but not so distinctly marked in its whole course. Into the inner space, between the upper and lower ridges, is inserted the complexus muscle, and into the outer space between the same, the splenitis muscle. The lower ridge is principally occupied by the origin of the superior oblique muscle of the neck. The inner space between this ridge and the great foramen gives origin to the rectus posticus minor, and the outer space to the rectus posticus major. Into a small elevation leading from the outside of the condyle directly to the margin of the bone, is inserted the rectus capitis lateralis. In a depression behind each condyle is the posterior con- dyloid foramen, which conducts a cervical vein to the lateral sinus. Passing through the base of the condyle, and having its orifice in front, is the anterior condyloid foramen, for con- ducting the hypoglossal nerve to the tongue. That part of the bone before the condyles is the cuneiform or basilar process; the base of which is marked, for the inser- tion of the recti muscles, by depressions, situated on the front of the vertebra; and its fore part, which is truncated at the end, overhangs the pharynx. The superior external part of the os occipitis is uniformly convex. The internal surface of the os occipitis is strongly im- pressed by ridges and depressions. On that portion of it behind the great foramen, is a rectangular cross, forming at its centre a large internal protuberance. The upper limb of vol. i.—p 114 SKELETON. the cross is marked by a fossa for the longitudinal sinus; the two horizontal limbs are also marked, each by its respective fossa, which receives the lateral sinus. The right fossa is frequently the largest. The inferior vertical limb of the cross has attached to it the small falx of the dura mater, and is slightly depressed by a small sinus. The spaces between the limbs of the cross are much thinner than other parts of the bone, and present broad concavities, the two superior of which receive the posterior lobes of the cerebrum, and the two inferior, the lobes of the cerebellum. The superior face of the cuneiform process is excavated longitudinally, to receive the medulla oblongata. On each side of the foramen magnum, a short curved fossa is observed, which receives the lateral sinus just before its exit from the cranium. The two superior margins of the occipital bone are regu- larly serrated. The inferior margins, have each, in their centre, a process termed the jugular eminence, which forms a part of the jugular fossa, for transmitting the internal ju- gular vein. The edge of the bone above this eminence is serrated, but below it is smooth and rounded, being simply parallel with the temporal bone. The occipital bone articulates above with the parietal, late- rally with the temporal, and in front with the sphenoid. 4. Temporal Bones, (Ossa Temporum.) These bones form portions of the inferior lateral parietes, and of the base of the cranium. Their figure is very irregular. The circular anterior por>- tion is called Squamous, behind it is the Mastoid, and be- tween the others is the Petrous. The Squamous Portion is thinner than the other bones of the cranium that have been described, from the temporal mus- THE CRANIUM. 115 cle and its fascia, covering it so as to afford sufficient pro- tection to the brain. Its exterior surface is smooth and slightly convex. The interior surface is formed into fossae by the convolutions of the brain. At the anterior part of the latter surface, a groove is made by the middle artery of the dura mater. The greater part of the circumference of this portion is sloped to a sharp edge, but at the anterior inferior part it is serrated and thicker. On the outside of the latter is the glenoid cavity, for articulating with the lower jaw, the long diameter of which is directed obliquely backwards. The anterior margin of this cavity is formed by a tubercle, on which the condyle of the lower jaw rises, when the mouth is widely opened. The outer margin of the glenoid cavity is formed by the root of the zygomatic process. The zygo- matic process,has a broad horizontal root, from which it ex- tends outwards, and then diminishing, runs forw ards to join the malar bone. Posterior to the root of the zygomatic pro- cess, a small vertical groove may be seen occasionally, made by the posterior deep seated temporal artery. The Mastoid Portion of the temporal bone, is thick and cellular. Its upper part forms an angle, which is received between the parietal and occipital bones, both margins of which angle are serrated. Below, is the mastoid process, a large conical projection eight lines long, into which are in- serted the sterno-mastoid, and trachelo-mastoid muscles. At the inner side of its base is a fossa affording origin to the digastric muscle. The inner face of the mastoid portion is marked by a deep large fossa for the lateral sinus of the brain. In the posterior part of the suture, uniting the mastoid por- tion and the occipital bones, or in the former bone near the suture, is the mastoid foramen, for conducting a vein from the integuments into the lateral sinus. The cells in the mastoid bone are so large and numerous, as to deserve the name of sinuses, and communicate with the tympanum by one large orifice. On the outer side of these sinuses a common diploic structure is observable. HG SKELETON. The Petrous Portion of the temporal bone is a triangular pyramid, arising by a broad base from the inner side of the mastoid and squamous portions. It is fixed obliquely for wards, between the sphenoid and occipital bones. Its ante- rior surface is marked by the convolutions of the brain. Near the centre of this* surface, and having a little superficial fur row leading to it, is a small foramen called the Hiatus Fal- lopii, through which passes the vidian nerve. The posterior surface of the petrous portion presents a large foramen, the Meatus Auditorius Internus, through which passes the se- venth pair of nerves. Half an inch behind this orifice, is a very small one, overhung by a flat shelf of bone; this is said to be the aqueduct of the vestibule. Just above the meatus auditorius is a foramen more patulous than the aque- duct, for transmitting small blood vessels. In the base of the petrous portion, between the mastoid and zygomatic processes, is the meatus auditorius externus, a large opening conducting to the tympanum. It is oval, about half an inch deep, and varies much in its size in dif- ferent subjects. Its margin is called the auditory process. the lower part of which is very rough, for attaching the car- tilage of the external ear. The lower surface of the petrous bone is exceedingly irre- gular. Immediately below the meatus externus, is a depres- sion which seems like a part of the glenoid cavity, and is improperly considered as such by anatomists, inasmuch as it does not form a portion of the articular surface for the lower jaw, but simply allows room for its motions, the parts which it contains (consisting of vessels, and a portion of the parotid gland) being pressed back when the jaw opens. Be- tween this cavity and the glenoid is the glenoidal fissure, separating the petrous from the squamous bone. In this fissure, leading to the tympanum, is a foramen which con- tains the processus gracilis of the malleus with its muscle, and the chorda tympani. The posterior margin of the de- pression alluded to in the petrous bone, is made by a long THE CRANIUM. in rough ridge, called processus vaginalis, just behind which, and partially surrounded by it, is the styloid process. The styloid process is round, tapering, and an inch and a half long, but frequently absent in prepared skulls, from accidental fracture, and from being in a cartilaginous state. From it arises the styloid muscles. Just behind the styloid process is the stylo mastoid fora- men, which transmits the portio dura nerve to the face. Just within the styloid process and foramen is a depression, call- ed jugular fossa, large enough to receive the tip of the little finger. The fossa, along with a corresponding one in the os occipitis, is occupied by the internal jugular vein and the eighth pair of nerves. Immediately before the lower end of the fossa is the foramen caroticum, being the lower orifice of a crooked canal, which terminates at the apex of the petrous bone, and transmits the carotid artery and the upper ex- tremity of the sympathetic nerve. Just in advance of the upper part of the fossa is a small spine of bone, at the foot of which is a pit, containing the orifice of the supposed aque- duct of the cochlea. This spine separates the eighth pair of nerves from the internal jugular vein. In the corner between the squamous and petrous bones, below the glenoid foramen, is the orifice of the Eustachian tube. The tube is divided longitudinally by a bony partition* The upper division contains the tensor tympani muscle. The temporal bone articulates with the Occipital, the Pa- rietal, the Sphenoid, and the Malar. 5. Sphenoid Bone, (Os Sphenoides.) The sphenoid is a symmetrical, but very irregular bone, placed transversely in the middle of the base of the cranium. It consists of a cuboidal body in the centre, of a very large process on either side of the body, and has, also, a number of angular margins and projections about it. 118 SKELETON. In regard to the body of the sphenoid bone; from its upper anterior part arise, one on either side, the Apophyses of In- grassias, or the little wings. These wings have a broad horizontal base, and extending themselves outwards, termi- nate in a sharp point. Their anterior edge is serrated for articulating with the os frontis, the posterior edge is smooth. Between the two wings in front, is a prominence united to the ethmoid bone. The base of the wing is perforated by the foramen opticum, for transmitting the optic nerve with the ophthalmic artery. Below and behind this foramen, the little wing terminates in a point, called the anterior clinoid process. Between the foramina optica is a ridge of bone, sometimes called processus olivaris, and just above the ridge a groove, made by the optic nerves where they unite. Be- hind the ridge is a depression, the Sella Turcica, for con- taining the pituitary gland. This depression is bounded behind by a more elevated transverse ridge, called the poste- rior clinoid process. At either extremity of the base of the latter, a groove is made by the carotid artery, which groove may be traced indistinctly under the anterior clinoid process, where it forms a notch, and sometimes a foramen. The posterior face of the body of the sphenoid bone, pre- sents a flat surface for articulating with the cuneiform pro- cess of the occipital. Most frequently, in the adult, the bones are anchylosed at this junction. The inferior part of the body of the sphenoid presents a rising, in its middle, called the sphenoidal or azygos process, for articulation with the vomer, and w ith the nasal septum of the ethmoid. On each side of this process, in front, is the orifice of the sphe- noidal cells. These cells consist most commonly of one on each side, and are separated by a bony partition. In the very young bone they are not formed. The body of the sphenoid undergoes so many changes between early infancy and adult life, by the conversion of its diploic structure into sinuses or cells, and is also so much modified in different individuals, that a general description of it will not answer for all specimens. THE CRANIUM. 110 The two great wings arise from the side of the body of the sphenoid, by a small irregular base. From their lower part project downwards, on either side, two pterygoid pro- cesses called external and internal. These processes have a common base, are partially separated behind by a groove called pterygoid fossa, and below by a notch. The internal is the longest, and is terminated by a hook, on the outer side of which is a trochlea made by the tendon of the circumflexus muscle. The external pterygoid process is the broadest. By applying together the temporal and sphenoid bones a groove, common to the two, leading to the Eustachian tube will be seen. This groove is continued obliquely across the root of the internal pterygoid process, and indicates the course of the cartilaginous portion of the Eustachian tube. The internal pterygoid process sends out, from its base, a small shelf of bone, separated, by a fissure, from the under part of the body of the sphenoid. The posterior edges of the vomer rest against these projections. The fissure is filled up in advanced life. The great wings of the sphenoid bone present three faces. One is anterior and called orbital, from its forming a part of the orbit; another is external, and called temporal; and the third is towards the brain, and forms a considerable part of the fossa for containing its middle lobe. The orbital face is square and slightly concave. The temporal face is an ob- long concavity, at the lower part of which is a triangular process giving origin to the external pterygoid muscle. The cerebral face is concave and marked by the convolutions of the brain. The inferior portion of the great wing is elon- gated backwards into a horizontal angle, called the spinous process, which is fixed between the petrous and squamous portions of the temporal bone. From the point of the spi- nous process projects downwards the styloid process. The great wing presents a triangular serrated surface above, at its outer end, by which it articulates with the os frontis; just below this, in front, is a short serrated edge by which it articulates with the malar bone; and, externally, is a 120 SKELETON. semicircular serrated edge, by which it articulates with the squamous portion of the temporal bone. The tip of the large wing generally articulates also with the parietal bone. Between the Apophyses of Ingrassias and the greater wings is the foramen lacerum, called also foramen lacerum supe- rius, of the orbit. It is broad near the body of the bone. and becomes a mere slit at the extremity of the little wing. Through it pass the third, fourth, first branch of the fifth, and the sixth pair of nerves. Two lines below the base of this hole is the foramen rotund um, for transmitting the second branch of the fifth pair of nerves. Eight lines, or there- abouts, behind the foramen rotundum, is the foramen ovale, for transmitting the third branch of the fifth pair of nerves. Two lines behind the foramen ovale is the foramen spinale, for transmitting the middle artery of the dura mater. In the under part of the bone, and passing through the root of the pterygoid processes, is the foramen pterygoideum, for transmitting the pterygoid nerve, it being a recurrent branch of the second branch of the fifth pair of nerves. The pterygoid bone articulates above and in front with the vomer, the frontal, ethmoidal and parietal bones; laterally with the temporal, behind with the occipital, and by its ptery- goid processes with the palate bones. 6. Ethmoid Bone, (Os Ethmoides.) This bone is placed between the orbitar processes of the os- frontis, and, as has been stated, fills the vacuity between them. It is cuboidal, extremely cellular and light. The horizontal portion between the orbitar processes is the cribiform plate, called so from its numerous perforations. This is divided longitudinally, above and below, by a verti- cal process; and from the under surface, on each side, is suspended a cellular portion. The vertical process on the superior face of the cribriform THE CRANIUM. 121 plate is the crista galli, which extends sometimes from the back to the front of the plate, and is thickest in the middle. The commencement of the great falx arises from it, and occa- sionally it contains a cell or sinus opening into the nose. Between the front of the crista galli and the os frontis, is the foramen ccecum already described. On either side of the crista galli the cribriform plate is depressed into a gutter for holding the bulb of the olfactory nerve, and is perforated with many holes for transmitting its ramifications. The most anterior foramen on each side is oval, and transmits to the nose the internal nasal nerve, after it has got into the cranium through the anterior internal orbitar foramen. The margins of the cribriform plate show many imperfect cells, which are completed by joining their congeners in the mar- gins of the orbital processes of the os frontis. The vertical plate below the cribriform is called nasal lamella. It generally divides the nostrils equally, but is occasionally inclined to one side. It joins below to the vomer and the cartilaginous septum of the nose ; in front is in con- tact with the nasal spine of the frontal bone; and behind with the azygos process of the sphenoid. Each cellular portion of the ethmoid forms, by its exterior, a part of the orbit of the eye, which surface is called os pla- num. The internal or nasal face forms part of the nostril. The fore part of this face is flat, but posteriorly in its middle is a deep sulcus, called the superior meatus of the nose. The upper turbinated bone, a small scroll, constitutes the upper margin of this meatus. The inferior internal margin of the cellular portion of the ethmoid, is formed by another scroll of bone, running its whole length. This is the middle turbi- nated bone. Moreover, from the inferior margin of the cel- lular portion, one or more lamiiiie, of an irregular form, pro- ject so as to diminish the opening into the upper maxillary sinus. The cells in the ethmoid bone are numerous and large, vol. i.—q, 122 SKELETON The posterior ones discharge, by one or more orifices, into the upper meatus. The anterior discharge into the middle meatus by several orifices, concealed by the inferior turbi- nated bone. The most anterior of these cells is funnel-shaped, and joining the frontal sinus, conducts the discharge of the latter into the nose. In children of from three to eight years of age, there is attached to the posterior part of each cellular portion of the ethmoid, a triangular hollow pyramid, consisting of a single cell. This pyramid arises not only from the cellular portion, but also from the posterior margin of the cribriform plate and of the nasal lamella, by which it gains a large and secure base. The processus azygos of the sphenoid bone is received between the two pyramids. In the base of the pyramid com- municating with the nose is a foramen, which is known in adult life as the orifice of the sphenoidal sinus. The pyra- mid, towards puberty, becomes a part of the sphenoidal bone, and then detaches itself, by a suture at its base, from the ethmoidal. As life advances it is greatly developed, no in- dication of its original condition remains, and it becomes fairly a sphenoidal cell; singularly differing in shape from what it was in the beginning.* Being put upon the investigation of this pyramid by the late Professor Wistar, w ith the view of ascertaining its dif- ferent phases of development, it has occurred to me to see it in every stage, from that of a simple triangular lamina, arising from the posterior margin of the cribriform plate, to the perfect hollow pyramidal state. Anatomists all describe it but imperfectly ; it remained for that distinguished indi- vidual to elucidate its real history'. Several of the articulations of the ethmoid have been men- tioned ; the remainder will be introduced with the bones of the face. * Wistar's Anatomy, vol. i. p. 31. third edition. THE FACE. 123 SECT. III.—OF THE FACE. The face being situated at the inferior anterior part of the base of the cranium, is bounded above by this cavity, laterally by the zygomatic arches and fossae, and posteriorly by the space occupied by the pharynx. The best way of obtaining precise information concerning its form and composition, is from the head of an infant, of from five to ten years, in which the bones can be easily parted. In the adult somewhat advanced in life, the bones cannot be separated so perfectly, from their being fused more or less together by the oblitera- tion of the sutures. The face is composed by fourteen bones, of which thirteen enter into the upper jaw. Twelve of the thirteen are in pairs: they are the ossa inaxillaria superiora, ossa malarum, ossa nasi, ossa unguis, ossa turbinata inferiora, ossa palati. The thirteenth is the vomer. A single bone, with correspond- ing or symmetrical sides, constitutes the maxilla inferior. 1. Superior Maxillary Bones, (Ossa Maxillaria Superiora.) These may be known by their superior size, and by their composing almost the whole front of the upper jaw. They arc too peculiar in their figures to admit of cpmparison with any common object. The superior face of these bones is formed by a thin trian- gular plate, which is the floor of the orbit. In the posterior part of this plate is a groove, leading to a canal terminating in the front of the bone, at the foramen infra orbitarium. This foramen is situated just below the middle of the lower margin of the orbit, and gives passage to the superior maxil- lary nerve, and an artery. Externally the triangular plate is terminated by a rough surface, the malar process, which articulates with the malar bone. The nasal process arises, by a thick, strong root, from the 124 SKELETON. front upper part of the bone at its inner side. Its front edge is thin, the posterior margin is thicker, and the upper edge is short, being serrated for articulating with the os frontis. A fissure exists between the orbitar plate and the nasal pro- cess, for accommodating the os unguis, and the lachrymal sac. A groove leading to the nose is formed on the posterior face of the nasal process, and marks the situation and ex- tent of the lachrymal sac. On that side of the root of the nasal process, next to the cavity of the nose, a small trans- verse ridge is seen, to which is attached the anterior part of the inferior turbinated bone. The under surface of the maxillare superius is marked by the alveolar processes for lodging the teeth. These processes are broader behind than before, corresponding in that respect with the teeth. Within the circle of the alveoli is the palate process, arising from the internal face of the body of the bone. The palate process has a thick root, is thin in the middle, and where it joins its fellow, has its margin turned upwards into a spine, whereby its articular surface is in- creased. It presents an oblong concave surface above, con- stituting the floor of the nostril; below, it, with its fellow and the alveolar processes, form one concavity, having a sur- face somewhat rough, which is the roof of the mouth. The palate process does not extend the whole length of the supe- rior maxillary.bone, but stops half an inch short of it poste- riorly, and with a serrated margin for the palate bone. When the two maxillae are in contact, in the suture just behind the front alveolar processes is seen the foramen incisivum, which bifurcates above into each nostril. This foramen contains a branch of the spheno-palatine nerve, and a ganglion formed from it. In front, just below the foramen infra orbitarium, the bone is depressed, which depression is filled up in the living state with fat and muscles. But behind, the maxilla is elevated into a" tuberosity, between which and the malar process is a broad groove, in which the temporal muscle plays. THE FACE. 125 The nasal face of the upper maxillary presents a view of the large cavity in the centre of it, called Antrum Highmo- rianum. The orifice by which this cavity communicates with the nose is much diminished by the palate bone behind, the efhmoid above, and the inferior spongy bone below. When the antrum is cut open a canal is seen on its posterior part, which conducts the nerve of the molar teeth to their roots, and a corresponding canal is seen in front of the antrum. The nerves in both instances come from the infra orbitary. The nerves, till they begin to divide into filaments, are be- tween the lining membrane and the antrum, but afterwards they make complete canals in the alveolar processes. The antrum frequently communicates with the frontal sinus, through the anterior ethmoidal cells, which observation is omitted by most anatomists. This bone is articulated with the frontal, nasal, unguiform, malar, and ethmoid, above ; to the palate bone behind; to its fellow, and to the vomer, at its middle; and to the inferior spongy bone by its nasal surface. 2. Palate Bones, (Ossa Palati.) The palate bones, two in number, are placed at the back part of the superior maxilla, between it and the pterygoid processes of the sphenoid. For descriptive purposes they may be divided into three portions—the horizontal or palate plate, the vertical or nasal plate, and the orbitar or oblique plate, placed at the upper extremity of the latter. The Palate Plate is continuous with the palate process of the superior maxillary bone, and supplies the deficiency caused by its abrupt termination. It is square. The infe- rior surface is flat, but rough for the attachment of the lining membrane of the mouth. The superior surface is concave, and forms about one third of the bottom of the nose. The anterior margin is serrated where it articulates with the 126 SKELETON. palate process of the upper maxilla. The posterior margin is thin and crescentic. The internal extremity of the cre- scent is elongated into a point, from which arises the azygos uvula; muscle. The internal margin of the palate plate is thick and serrated for articulating with its fellow, the iippi* edge of it being turned upwards to join the vomer. The exterior edge touches the internal side of the upper maxilla, and from it arises the nasal plate. The Nasal Plate forms the posterior external part of the nostril, and is much thinner than the palate plate. Its side next the nose is slightly concave, and is divided into two unequal surfaces, of which the lower is the smallest, by a transverse ridge, that receives the posterior extremity of the lower turbinated or spongy bone. The external face is in contact with the internal face of the maxillary bone, and presents a surface corresponding with it. The nasal plate of the palate bone diminishes the opening into the antrum Highmorianum by overlapping it. Backwards it joins the pterygoid process of the sphenoid bone, and overlaps its an- terior internal surface. At the inferior and posterior part of the nasal plate where the crescentic edge of the palate plate joins it, the palate bone is extended into a triangular process called the ptery- goid. This process, on its posterior surface, presents three grooves, the internal of which receives the internal pterygoid process of the sphenoid bone, and the external groove receives the external pterygoid process of the same bone. The middle fossa has its surface continuous with the pterygoid fossa of the sphenoid bone, and may be seen, in the articulated head, to participate in this fossa. The anterior surface of the pterygoid process of the palate bone, presents a small ser- rated tuberosity, which is received into a corresponding con- cavity on the posterior surface of the maxillary bone, and contributes to the firmer junction of the two. On the external surface of the nasal plate, between it and THE FACE 127 the base of the pterygoid process, a groove is formed, which is converted into a complete canal by the maxillary bone. The lower orifice of this canal is near the posterior margin of the palate. It is called the posterior palatine foramen, and transmits the nerve and artery to the soft palate. Imme- diately behind this canal there is, not unfrequently, a smaller one, running through the base of the pterygoid process of the palate bone, and transmitting a filament of the same nerve to the palate. The upper extremity of the nasal plate is formed by two processes, one in front and the other behind, separated either by a round notch or by a foramen. The posterior of the two, called also pterygoid apophysis, is inclined over towards the cavity of the nose. It is thin, and fits upon the under sur- face of the body of the sphenoid bone, and upon the inner surface of the internal base of the pterygoid process of the same. Its upper edge touches the base of the vomer. The anterior process is the orbitar portion of the palate bone. The Orbitar Portion is longer than the pterygoid apophy- sis, and is cellular and very irregular. It may be seen in the posterior part of the orbit wedged in between the ethmoid and maxillary bones. The portion of it which is there seen, is the orbital face, and is triangular. On the side of the eth- moid bone its cells are seen, which are completed by their contiguity to the ethmoid. The cells, in young subjects, are not always to be met with. The posterior face of the orbitar portion is winding and looks towards the zygomatic fossa. The notch between the orbitar portion and the pterygoid apophysis is converted into a foramen, by that part of the body of the sphenoid bone which is immediatly below the opening of the sphenoid cell. Through this foramen, called spheno palatine, pass the lateral nasal nerve, the spheno pa- latine artery and vein. 128 SKELETON. This bone can scarcely be studied advantageously except in the separated head. A single application of it to the maxillary, will then show how it extends from the palate of the mouth to the orbit of the eye. And how it is the con- necting bone between the maxillary and the pterygoid pro- cess of the sphenoid. The palate bone articulates with six others. With the maxillary, the sphenoid, the ethmoid, the inferior spongy, the vomer, and with its fellow. The places of junction have been pointed out in the description of the bone. 3. Nasal Bones, (Ossa Nasi.) The ossa nasi, two in number, fill up the vacancy between the nasal processes of the superior maxillary bones. They are oblong and of a dense compact structure, being so ap- plied to each other as to form a strong arch called the bridge of the nose, which is further sustained by the nasal spine and the continuous oblique serrated surface of the os frontis. The ossa nasi are thick and serrated at their upper mar- gins, below they are thin and irregular. The surfaces by which they unite with each other are broad, having their edges raised where they join the nasal lamella of the ethmoid bone. The edge by which they join the nasal process of the upper maxillary bone is concave; the upper part of this edge is overlapped by the nasal process, but the lower part of it overlaps the nasal process. On the posterior face of the os nasi, is to be seen a small longitudinal groove, formed by the nasal branch of the oph- thalmic nerve, which penetrates the foramen orbitale ante- rius and the cribriform plate of the ethmoid bone. The ossa nasi articulate with each other in front, with the nasal processes of the upper maxillary behind, and with the septum narium internally. THE FACE. 129 4. Unguiform Bones, (Ossa Unguis.) The unguiform is a very small thin bone, placed at the internal corner of the orbit, between the nasal process of the upper maxilla and the os planum. Its orbitar surface is di- vided into a face which is continuous with that of the os planum, and into an oblong vertical concavity, continuous with the concavity on the posterior surface of the nasal pro- cess, for lodging the lachrymal sac. Its inferior anterior corner is elongated into the nose, sp as to join with a pro- cess of the inferior turbinated bone, whereby the ductus ad nasum is rendered a complete bony canal. This bone lies on the orbitar side of the most anterior eth- moid cells, and completes them in that direction. An important variety in the structure of this part of the orbit occasionally occurs, in which the whole fossa for lodg- ing the lachrymal sac, is formed by the unusual breadth of the nasal process of the upper maxillary bone. In this case the only part of the os unguis which exists, is that in the same line with the os planum. Several examples have come under my own notice. Duverney has also mentioned it. Sometimes it is entirely wanting, in which case the os planum joins the nasal process.* A variety still more uncommon is mentioned by Verheyen, where the lachrymal fossa is formed exclusively by the os unguis. This bone articulates very loosely with the adjoining bones, so that it is frequently lost from the skeleton. It joins the os frontis above, the upper maxilla before and below, the os planum behind, and the inferior spongy bone in the nose. 5. Cheek Bones, (Ossa Malarum.) These bones, two in number, are also called zygomatic by many anatomists. They are situated at the external part * Bertin Traite D'Osteol. vol. II. p. 143. Paris, 1754. VOL. I.—R 130 SKELETON of the orbit of the eye, and form the middle external part of the face. The cheek bone is quadrangular, and has irregular mar- gins. It consists of two compact tables with but little inter- mediate diploic structure. There are three surfaces to it. That which contributes to the orbit is crescentic, and is called the internal orbitar pro- cess. The one in front is convex, and forms part of the face; and behind the latter is a third surface, which is concave, and forms a part of theJ(zygomatic fossa. Of the four mar- gins, two are superior, and two inferior. The anterior of the two first is concave, and rounded off, to form the exter- nal and one-half of the lower edge of the orbit. The poste- rior upper border above, is thin and irregular, and to it is attached the temporal fascia ; it terminates behind by a short serrated margin, for articulating with the zygomatic process of the temporal bone. The anterior inferior margin, is ser- rated its whole length, for articulating with the superior maxillary bone. The posterior inferior margin, gives origin to part of the masseter muscle. Some anatomists admit, also, a fifth margin to this bone, which is towards the bottom of the orbit, and articulates above with the great wing of the sphenoid bone, and below7 with the superior maxillary. Be- tween these two parts is a notch, forming the outer extremity of the spheno-maxillary slit. The angles of this bone are called processes. The upper one, which is continuous with the external angle of the os frontis, is the superior orbitar, or angular process. The or- bitar margin terminates below in the inferior orbitar, or an- gular process. That portion of the bone which joins with the zygoma of the temporal, is the zygomatic process ; and the fourth angle is the maxillary process. The os malse articulates with four bones ; to wit, with the maxillary, frontal, sphenoidal, and temporal. There are a few small foramina in this bone, which trans mit nerves and blood vessels. THE FACE. 131 6. Inferior Spongy Bones, (Ossa Spongiosa aut Turbinata Inferior a.) This pair of bones is situated at the inferior lateral parts of the nose, just below the opening into the Antrum Highmo- rianum. They are very thin and porous, and theirsubstance is extremely light and spongy. The internal face of the spongy bone is towards the sep- tum of the nose, and presents an oblong rough convexity. The external face has a corresponding concavity towards the maxillary bone. The superior margin presents in front, an upright process which joins with the anterior inferior an- gle of the unguiform bone, to form the nasal duct Just be- hind this, the margin of the bone is turned over towards the antrum, forming a broad hook, which rests upon the lower margin of the orifice of the antrum, and diminishes its size. From the superior margin, also, one or two processes not un- frequently arise, whereby this bone joins the ethmoid. The inferior margin is somewhat thicker than the superior. The anterior extremity of this bone rests upon the ridge across the root of the nasal process of the upper maxillary. The posterior extremity rests, in like manner, upon the ridge across the nasal plate of the palate bone.* The Plowshare, (Vomer.) This single bone is placed between the nostrils, and forms a considerable part of their septum. It is frequently more inclined to one side than to the other. It is formed of two lamina?, between which there is a very thin diploic structure. The sides of the vomer are smooth and parallel. It has four margins. The superior is the broadest, and has a fur- row in it for receiving the azygos process of the sphenoid bone. The anterior margin is directed obliquely downwards, and forwards, of which the front half joins the cartilaginous • In some rare cases this bone adheres to the ethmoid so as to become a part of it. 132 SKELETON. septum of the nose, and the other half receives, in a narrow groove, the nasal plate of the ethmoid. The posterior margin of the vomer is smooth and rounded, making the partition of the nostrils behind. The inferior margin articulates with the nasal spine of the superior max- illary and palate bones. Lower Jaw, (Os Muxillare Infcrius.') This bone forms the lower boundary of the face, and is the only one in the cranium capable of motion. In early life, its two halves are separable, being united at the chin only b} cartilage ; but, in the course of two or three years after birth, they are firmly united, and the original cartilage disap- pears. It consists of a body and two extremities or branches. The inferior part of the body presents a thick and rounded edge ; it is the base. The upper part of the body is formed by the alveolar cavities for receiving the teeth. The line of union between the two halves, called their symphysis, is marked in front by an elevated ridge, terminated below by a triangular tubercle. In many subjects this#tubercle is bounded on each side by a rounded prominence of bone, which gives to the fore part of the jaw an unusual squareness in the living subject. Just above the latter prominence, there is on each side a transverse depression, from which arises the levator muscle of the lower lip. On a line with this depres- sion, and removed a little distance from its external extre- mity, under the insterstice between the second small and the first large molar tooth, is the anterior mental or maxil- lary foramen, the termination of a large canal in either side of thebone which conducts the inferior maxillary blood vessels to the teeth. The foramen is directed obliquely upwards and backwards, and transmits the remains of the blood vessels and nerves to the face. As the alveolar processes do not exist in early life, and in very advanced age, when the teeth are lost, the anterior mental foramina in such cases are very near the superior margin of the bone. At them an obtuse ridge of bone commences, which ends in the root or anterior THE FACE. 133 edge of the coronoid process. The alveolar processes of the three last molar teeth are placed within this ridge, and pro- jects over the internal face of the bone. The internal or posterior face of the lower jaw is also marked at the symphysis by a ridge passing from the supe- rior to the inferior margin. At the lower part of this ridge is a cleft process, the posterior mental tubercle. Below this tubercle, on either side, is a shallow fossa for re- ceiving the digastric muscle. Between the lower margin of the bone and the protuberance occasioned by the posterior alveolar processes, is an oblong large fossa, made by the pressure of the sub-maxillary gland. The alveolar processes form a semicircle, the extremities of which are carried backwards with a slight divergence. The parietes of these processes are thin, and present cutting edges. They of course correspond, in number and shape, * with the roots of the teeth which they have to accommo- date. The anterior ones are longer than the posterior. As a general rule, the alveolar processes may be said to come and depart with the teeth; but, when a single tooth is ex- tracted, the alveolar cavity not unfrequently is filled up with osseous matter, the edge of it alone being removed. This occurs more frequently in the lower than in the upper jaw. The base of the lower jaw does not present many marks worthy of attention. It should be observed, that its anterior part is thicker than the posterior. Sometimes, just before the angle of the bone, we see a concavity of this edge; but generally it is straight, or nearly so. The extremities or rami of the lower jaw are quadrilateral, and rise up much above the level of the body. Their supe- rior margin presents a thin concave edge, bounded in front by the coronoid, and behind by the condyloid process. The coronoid process is triangular; its base is thick, but its apex is a thin rounded point. The condyloid process is a transverse cylindrical ridge, directed inwards with a slight inclination backwards, its middle being somewhat more ele- vated than the extremities. There is a concavity at the fore 134 SKELETON part of its root for the pterygoideus externus, and a convex- ity behind. It springs from the ramus by a narrow neck. The external face of the ramus is flat, but marked by the insertion of the masseter muscle. The internal face at its lower part is flat and rough, for the insertion of the ptery- goideus internus. At the upper part of this roughness is the posterior mental or maxillary foramen, through which the aforesaid vessels and the nerve enter. It is partially concealed by a spine of bone, into which a ligament from the os tem- poris is inserted. Leading from this foramen is a small superficial groove, made by a filament of the submaxillary nerve. The angle of the inferior maxillary bone, formed by the meeting of the base and the posterior margin of the ramus, presents diversities well worth attention, at different epochs of life, and in different individuals. In very early life, and in very advanced, when the alveoli are absorbed, it is remark- ably obtuse. In most middle aged individuals it is nearly rectangular. Besides which, its corner is sometimes bent outwards and sometimes inwards, increasing or diminishing thereby the breadth of the face at its lower part The substance of this bone externally is hard and compact. Internally there is a cellular structure, through the centre of which runs the canal for the nerves and blood vessels. From this canal smaller ones are detached, containing the vascu- lar and nervous filaments which run to the roots of the teeth. The maxilla inferior articulates with the temporal bones, by means of their glenoid cavities. Remarks.—The maxilla inferior has a greater influence on the form of the face than any other bone entering into its composition. Sometimes it is much smaller in proportion in certain individuals than in others. Sometimes its sides, being widely separated, give a great shortening to the chin, and breadth to the lower hind part of the face. In many instances, the alveolar processess in front incline obliquely over the outer circumference of the bone, and thereby give to ARTICULATION OF THE LOWER JAW. 135 the chin the appearance of receding considerably. In others, the alveoli incline over the inner circumference, which causes the chin to project unusually. SECT. IV.—ARTICULATION OF THE LOWER JAW. The articular surfaces here are formed by that portion of the glenoid cavities anterior to the fissure in them, and by .the condyles of the lower jaw. Each surface is covered by thin cartilage; and a thin, loose, irregularly fibrous, capsular liga- ment, arises from the articular margin of one bone, to be inserted into that of the other. Besides this there are four other ligaments for strengthening the joint, an inter-articular cartilage, and two synovial membranes. The External Ligament also called Membrana Articularis Ligamentosa, arises from the inferior margin of the jugal or zygomatic process of the temporal bone, and from the an- terior side of the meatus externus, and is inserted into the neck of the condyloid process. It is somewhat triangular, having the base upwards. Just in advance of this, and sepa- parated from it by a small fissure is another triangular liga- ment, the discovery of which is claimed by Caldani.* It arises from the anterior part of the inferior margin of the zygoma, and is inserted into the neck of the bone in advance of the other. The Internal Ligament arises from the extremity of the spinous process of the sphenoid bone, and from the posterior margin of the glenoid cavity, and going downwards and out- wards, is inserted into the spine bordering the posterior men- tal foramen and for some distance lower down on the ramus of the jaw. It is placed between the two pterygoid muscles, and is in contact with the maxillary vessels and nerves, as they run between it and the condyle to the posterior mental " Tabul. Anat. Venetiis, 1802. 136 SKELETON foramen. It is thought by Caldani to be not so useful in restricting the motion of the jaw forwards, as in holding the vessels and nerves, and regulating their position, lest in the various motions of the lower jaw, they should be displaced and injured. The Stylo Maxillary Ligament is thinner than the above. It arises from the external side of the styloid process, and is inserted into the posterior margin of the jaw, near its angle between the masseter and internal pterygoid muscles. The stylo glossus muscle is much connected with it, and is thereby assisted in elevating the base of the tongue. There are two Synovial Membranes, the one reflected be- tween the glenoid cavity and the upper surface of the inter- articular cartilage, and the other between this latter substance and the condyle of the lower jaw. They may be seen at dif- ferent points protruding between the fibres of the capsular ligament. The Inter-articular Cartilage by being placed between the two synovial membranes, separates completely the two bones. Above its surface corresponds to the convexity of the tuber- cle of the temporal bone, and to the glenoidal cavity; below it is simply concave for receiving the condyle. It is thicker at the circumference than in its middle, and at the posterior than the anterior margin. Sometimes it is open in the cen- tre, in which case the twro synovial membranes run into one another. Its structure is fibro-cartilaginous. It moves very readily backwards and forwards. On the posterior face of the capsular ligament, I have found in several cases, indeed on all occasions of special ex- amination for it, since the first observation, an erectile tissue or structure resembling the corpus cavernosum penis. It has not been filled with blood like the latter, but is probably an arrangement for giving great mobility forwards to the lower jaw. ARTICULATION OF THE LOWER JAW. 137 The movements of this bone may be simply hinge-like, by its depression, in which the mouth is regularly opened ; or, by the action of the pterygoid muscles, it may be slid for- wards. When the muscles of but one side act, a species of rotation is communicated, in which one condyle advances on the tubercle of the temporal bone, while the other reaches to the back part of the glenoid cavity. The looseness and length of the capsular ligament of the articulation, along with the extreme facility of motion from the interposition of a moveable cartilage, contribute very materially to this move- ment. When the synovial fluid of the articulation is deficient and over inspissated, the sliding backwards and forwards of the intermediate cartilage during mastication, sometimes produces a crackling, audible to the by-standers; and ex- tremely annoying to the. individual who is the subject of it, from the noise being so near his ear. Some persons are liable to a spontaneous dislocation of this bone, from yawning too widely. I am disposed to be- lieve, that in such cases the accident arises from the posterior boundary of the glenoid cavity, (as established by that mar- gin of the temporal bone which is continuous with the vaginal process, and forms a part of the meatus externus,) being more advanced and high than usual; in consequence of which, whenever the bone is depressed to a certain point, its neck strikes against this ridge, and not being able to go further back, the ridge acts as a fulcrum, and starts the condyle over the tubercle of the temporal bone into the zygomatic fossa. The fact is certain, that very strongly marked differences of the glenoid cavity, in this particular, occur in different individuals. vol. i.—s 13$ SKELETON. CHAPTER III. GENERAL CONSIDERATIONS ON THE HEAL> Having described the individual bones of the head, it will now be proper to consider it as a whole. SECT. I.—OF THE SUTURES. Except in advanced age, the bones of the cranium and of the face are very distinctly marked off and united by sutures. The latter are formed by the proximate edges of the bones, presenting a multitude of sharp serrated points, and of deep narrow pits, by which they are brought into accurate and firm contact. Here and there, in the sutures which unite the flat bones of the cranium, we find not only sharp points, but complete dovetail processes of the one bone received into corresponding cavities of the other. The denticulation of the sutures is much more common, and much better marked, on the external than on the internal surface of the cranium. On the latter, the union of the bones is, in several instances, by a joint nearly straight, in which case, the denticulation is almost exclusively confined to the external table and to the diploic structure. The Coronal Suture, named so from its corresponding in situation with the garlands worn by the ancients, begins at the sphenoid bone, about an inch and a quarter behind the external angular process of the os frontis. It inclines so much backwards in its ascent, that when we stand erect with the head in its easiest position, a vertical line, dropped from its point of union with the sagittal suture, would pass through the centre of the base of the cranium, and would cut another line drawn from one meatus auditorius externus to the other. It unites the frontal bone to the two parietal. THE SUTURES. 139 The Sagittal Suture unites the upper margins of the two parietal bones, and is immediately over the division between the hemispheres of the cerebrum. It has been stated in the account of the os frontis, that sometimes it is continued through the middle of this bone down to the root of the nose. The Lambdoidal Suture is named from its resemblance to the Greek letter lambda, and consists of two long legs united angularly. It begins at the posterior termination of the sa- gittal suture, and continues down to the base of the cranium, as far as the jugular eminences of the occipital bone. Its upper half unites the occipital to the parietal bones, and the lower half the occipital to the temporal bones. The latter half is sometimes called the additamentum sutur* lambdoides* The Squamous Suture is placed on the side of the head, and unites the parietal to the temporal bones. The convex semicircular edge of the latter overlaps the concave edge of the former. The squamous suture is converted into the com- mon serrated one where the upper edge of the angle of the temporal bone joins the parietal. In the upper part of the Lambdoidal Suture particularly, we find in many skulls one or more small bones, connected to the parietal and occipital bones by serrated margins. They are called the Ossa Wormiana or Triquetra. They vary very much in their magnitude, being in different subjects from a line to one inch, or an inch and a half in diameter. I have seen one of the latter size, which occupied entirely the place of the superior angle of the os occipitis. Most com- monly, but not always, when one of these bones exists on one side of the body, a corresponding one exists on the other. A congeries of these bones united successively is sometimes found in the lambdoidal suture; in such cases, they are for the most part small. Commonly these bones consist, like the other bones of the cranium, of two tables and an intermediate diploe, and form an integral portion of the thickness of the cranium; sometimes, however, they compose only the external 110 SKELETON. table. Mr. Bertin says, that he has seen them also, compos- ing only the internal table of the cranium. All the sutures mentioned may exhibit, at any of their points, the Ossa Triquetra or Wormiana : besides the lamb- doid. I have seen them in the coronal, tli£ sagittal, and the squamous, but in such cases they are small. The lambdoid unquestionably has them most frequently. Mr. Bertin has seen a large square bone at the fore part of the sagittal su- ture, occupying the place, and presenting the form, of what was once the anterior fontanel: He has also seen the tri- quetral bones in the articulations of the bones of the face.* The sutures described belong exclusively to the cranium, but there are others common to it and to the face. The Sphenoidal suture surrounds the bone from which its name comes.—The Ethmoidal suture surrounds the ethmoidal hone —the Zygomatic suture unites the temporal and malar bones —the Transverse suture runs across the root of the nose, and also unites the malar bones to the os frontis. The other articular surfaces of the face derive their names from the bones they unite, and do not merit a particular attention at this time, as enough has been said in the description of the bones themselves. The base of the cranium is remarkably different, in the manner of its articulations, from the upper part. The sur- face, in the first place, is very rugged, and much diversified by its connexion with muscles and bones, besides which there is a considerable number of large foramina and fissures in it. In order to guard against the weakness arising from the latter arrangement, nature has given a very increased thick- ness to it, particularly where much pressure from the weight of the head exists, and has applied unusually broad surfaces of bone to each other to secure their connexion, from dis- placement by the effects of concussion, and different kinds of violence. These circumstances are particularly manifest • Bertin, loc. cit. THE SUTURES. 1 J, J at the junction of the cuneiform process of the occipital hone with the body of the sphenoid, which, in the middle aged, is most frequently anchylosed ;—at the lower part of the lamb- doidal suture ;—and at the margins of the petrous portions of the temporal bones, where they touch the contiguous bones. Whence it results that the several fastenings of the base of the cranium, and of the upper maxilla, are so complete and strong, that they are most generally perfectly exempt from dislocation, and when the violence offered to them is suffi- ciently great, instead of it they are fractured. It is somewhat problematical why the sutures arc formed at all, in the cranium and upper maxilla; for as none of their bones are intended for motiou upon each other, it seems that the head might have been equally well constituted by being- made of a single piece, that is to say, so far as the establish- ment of its several cavities is concerned. In proof of which it is only necessary to recollect that in the very aged, there is frequently not a bone of the head to be found in an insulated state; they are all fused, by the obliteration of their sutures. into the adjoining bones. The old notion that sutures existed for the purpose of arresting the course of fractures, and for opening in particular diseased conditions of the brain, has been very justly exploded. For we know that a fracture will traverse a suture as readily as it will any other part; and that the opening of the sutures is an occurrence of very early infancy, from hydrocephalus, where the sutures have never arrived at their serrated and dove-tail arrange- ment, by which they are subsequently secured. It is much more probable that the true reason of the existence of the sutures, is to be found among the laws which belong exclu- sively to the growing state; and which most commonly are suspended after the several developments have been accom- plished. Thus the bead, in consequence of being separated by sutures into many pieces, is more readily wrought from its form and size in the embryo state, to the form and size required by adult life. This necessity of subdivision into many pieces, does not depend so much on the size, as on the 142 SKELETON. shape of the head. For we find the largest animal, as the elephant, having no more sutures than the smallest, as the mouse. This opinion is also sustained by what we see in other bones. Bones of a very simple shape, as those of the tarsus and carpus, consist from the very beginning of but one piece. But where the shape of a bone is complicated, we find it, while growing, submitted to the same law as the head at large, and consisting of many pieces. In such cases these pieces are unit- ed by a species of suture corresponding precisely with the form of suture observed betwreen some of the bones of the cranium, as, for example, between the occipital and the sphenoid. Thus the os femoris, till adult age, consists of five pieces, its two articular extremities, its body, its trochanter major, and its trochanter minor. The cranium itself, before birth, and for some time after, has several of its individual bones consisting each of two or more pieces, which favours still more the idea. Some persons think that the sutures of the adult are only remains of an arrangement intended exclusively for the benefit of the parturient state, by maintaining a plasticity of the head of the foetus, which admits of its diameters accommodating themselves to the diameters of the pelvis of the mother. This theory is rather too exclusive, though it may be admitted that the sutures in a foetal head have that use, and are a most for- tunate concurrence in some cases of parturition, by which the life of both parties is saved. But it should also be observed that in a great number of cases, the head of the foetus never changes its form in passing through the pelvis, because the passage is quite large enough without it; and again, if the sutures were intended expressly for the parturient state, we ought not to find them in birds, and in such animals as arc hatched, because the necessity for them there does not exist* Upon the whole we may safely conclude, that the sutures of the cranium and face are simply a provision for the grow- ing state, and that like all other provisions for this state, it * A gentleman whose anatomical writings have some vogue in this coun- try, has cut the Gordian knot, by telling us that they are of " little use, merely nccidental.'*<—KvaX. of the H. Body, by John Bell, Surgeon, Edinburg. THE SUTURES. 143 also ceases at its appropriate period, and sometimes leaves not a vestige of its existence. Occasionally indeed, we find the latter to have occurred in one or more sutures, even be- fore the age of puberty, as I have repeatedly witnessed of the sagittal, the squamous, and the lambdoidal sutures. The manner in which the Sutures are formed is sufficiently interesting ; they are generally said, to be made by the radii of ossification, from the opposite bones meeting and "passing each other, so as to form a serrated edge. This explanation may account partially for the shape of the edge of the sutures, but not for their invariable position, inasmuch as we always find the sutures in the same relative situation, and having the same course. If they depended exclusively on so me- chanical a process, as the rays of one bone shooting across the rays of another by their own force, we ought to find oc- casionally, the sagittal suture more on one side of the head than on the other, and not straight, because in some instances ossification is a more rapid process on one side than on the other. Moreover, in all cases where bones arise from dif- ferent points of ossification and meet, the serrated edge should be formed; and particularly in the flat bones. Observation, however, proves that the os occipitis, which is formed ori- ginally from four points of ossification, and therefore has as many bones composing it in early life, never presents these bones afterwards united by the serrated edge. The acromion process of the scapula, though originally distinct from the spine, never unites to it by suture, but always by fusion. The mode of junction in the three bones of the sternum is always by fusion. In short, the observation holds good in numerous other instances. Bertin and Bichat, reject fully the mechanical doctrine concerning the sutures, and present one founded upon reason and observation, and susceptible of confirmation by any ac- curate observer. The dura mater and the pericranium, be- fore ossification commences, form one membrane consisting of two laminse. Partitions pass from one of these laminse to the other, which mark off the shape, or constitute the mould 144 SKELETON. of the bone, long before the bone is perfected. The peculiar shape of the bony junction, or in other words, of the sutures or edges of the bones in adult life, depends, therefore, exclu- sively upon the original shape of the partitions. When the latter are serrated, the points of ossification will fill up these serra, but when they are oblique, the squamous suture will be subsequently formed. This theory also accounts for modes of junction interme- diate to the squamous and serrated suture. For the forma- tion of the ossa triquctra or wormiana. For their existence, form, size, and number, in some skulls, and their total ab- sence in others. The inference will also be obvious, that in all ossifications from different, nuclei, a suture will not be formed, where the membranous partitions do not exist; but that the bones will unite after the manner of such as are frac- tured. We shall also understand, that when these partitions are weak and imperfect, either from their congenital condi- tion ; or from advanced age, as happens in all sutures, but with some differences of time; the bones of the opposite sides are fused together completely. The partitions which determine the places of the sutures, may be demonstrated in a young adult skull by removing with muriatic acid the calcareous portion of the bones, so as to leave only the animal part. On opening the suture after this process, it will be seen, that the pericranium sends in its partition, which is met by the partition .coming from the dura mater. Or, if either of these membranes be pealed off, its contribution of partition will appear very plainly project- ing from its surface, in the form of a serrated or serpentine ridge. Owing to congenital hydrocephalus, the sutures of the vault of the cranium have been known to remain open for years after birth, from the continued augmentation of the volume of the brain. In such cases additional bones are sometimes formed, manifesting a strong attempt, on the part of nature, to cover the brain with bone. I obtained, a few DIPLOE. 145 years ago, a specimen of this kind belonging to a foetus of nine months, whose head was as large as it is commonly in adult life, and in whom there were two ossa parietalia on one side. Morgagni,* whose authority is proverbial in mor- bid anatomy, states, that a learned colleague and intimate friend of his, Bernardin Rammazzani, aged seventy, had the sutures open at that period of life. He does not say at what time this condition of them appeared. I think it more pro- bable that they had never been closed, though Morgagni leaves the reader to infer, that it was a circumstance which had arisen from a violent hemicrania, with which the patient had been seized when he was advanced in life. Diemerbroek found in a woman of forty, the anterior fontanel not ossified. Bauhius' wife, aged twenty-six, had the sutures not yet closed. Indeed, there is no deficiency of well authenticated similar instances, more of which it will be unnecessary to adduce. It may be observed here, that when from congeni- tal hydrocephalus attended with much extension of the brain, the bones of the cranium are compelled to grow beyond their usual diameters, they are uncommonly thin, and the diploic structure is very imperfectly developed, which will account for their separation at any period of life, from the fastening being so slight. SECT. II.__OF THE DIPLOIC STRUCTURE OF THE CRANIUM. The bones of the cranium, in the adult, consist of an ex- ternal and of an internal table, united by a bony reticulated or cellular substance. The latter does not manifest itself very distinctly till two, three, or even more years are passed by the infant. The internal table of the skull is thinner and more brittle than the external, which has obtained for it the name of vitreous table. The cells of the diploic structure are not to be confounded with the large sinuses that exist in the frontal, the temporal, and the sphenoidal bones. They are formed under different circumstances, and do not communicate with them. The • Causes and Seats of Disease, Letter 3d Art. 8ih. VOL. I.—T 14U SKELETON. sinuses are lined by a mucous membrane, whereas the lining membrane of the cells of the diploe corresponds with the in- ternal periosteum of other bones. I have a preparation now before me, in which the diploic structure of the os frontis exists between its sinuses and the external table of the bone : in the same head a similar circumstance existed in regard to the temporal bone, from which we infer that the diploic struc- ture, in these places, is caused to recede and even to be par- tially obliterated when the development of the sinus com- mences, which is not till some time after the evolution of the diploic structure. In the diploe of the dried bones several arborescent chan- nels* may be seen, by the removal of the external table. They were discovered about twenty years ago by M. Fleury, while he was Prosecteur at the School of Medicine in Paris; and engaged, at the instigation of the venerable Chaussier, in some inquiries relative to the structure of the cranium. The account given by the latter is, that these channels are occupied by veins in the recent subject, which, like all other veins, are intended to return the blood to the heart. These veins are furnished with small valves, have extremely thin and delicate parietes, and commence by capillary ramifica- tions, coming from the different points of the vascular mem- brane, which lines the cells of the diploe. Their roots are at first extremely fine and numerous, form by their frequent anastomoses a kind of network, and produce by their succes- sive junction, ramuscules, branches, and large trunks, which, becoming still more voluminous, are directed towards the base of the cranium. Some variations exist in regard to the number, size, and disposition of these trunks, but gene- rally one or two of them are found in either side of the fron- tal bone, two in the parietal bone, and one in either side of the occipital bone. Anastomoses exist between these seve- ral trunks, by which the veins in the parietal bone are joined to those in the frontal and in the occipital. Branches from the right side of the head also anastomose, with some from * Chaussier, Exposition de la Structure de l'Ence'phale. Paris, 1807. SURFACES OF THE CRANIUM. 147 the left side. Besides the branches already mentioned, one or two smaller than the others are directed towards the top of the head, and terminate in the longitudinal sinus. The descending veins of the diploe communicate in their passage with the contiguous superficial veins, and empty into them the blood which they receive from the several points of the diploe. These communications are produced through small foramina, which penetrate from the surface of the bone to the diploe. The trunks of such diploic veins as are con- tinued to the base of the cranium, open, partly into the sinuses of the dura mater, and partly into the venous plexus at the base of the pterygoid apophyses, and form there the venous communications called the emissaries of Santorini. More- over there are communications sent from the diploic veins, through the porosities of the internal table of the skull, to the veins of the dura mater. This fact is rendered very evident by tearing off the skull cap, when the surface of the dura mater will be studded with dots of blood, and the inter- nal face of the bone also, particularly in apoplectic subjects. It appears indeed that the arteries of the cranium are prin- cipally distributed on its external surface, and the veins on its internal surface and diploe. In the infant the diploic veins are small, straight, and have but few branches : in the adult they correspond with the description just given, and in old age they are still more considerable, forming nodes and seeming varicose. In chil- dren, when the bones are diseased, they partake of the latter character. In order to see them fully, the external table of the skull must be removed, both from its vault and base, with a chisel and mallet. This operation will be much faci- litated by soaking the head previously in water, for two days. SECT. III.—THE INTERNAL SURFACE OF THE CRANIUM. The points for study in viewing the cranium as a whole, are generally the same as have been presented in the detail 148 SKELETON. of each bone. It is nevertheless useful to regard the struc- ture in its connected state, as new views are thus presented of the relative situation of parts, and of the formation of the several fossae and cavities. The cavity for containing the brain is regularly concave above, and called the arch or vault; but below, it is divided into several fossae, and is called the base. The whole cavity is lined by the dura mater, and in the adult presents round superficial depressions made by the con- volutions of the brain. These depressions are seldom deep enough to prevent the internal periphery of the vault and sides of the cranium, from being nearly parallel with their external surface. On'the Vault, or arch, are to be seen, on the middle line, the frontal spine, extending from the ethmoid bone half way or more up the os frontis : also the gutter for the longitudinal sinus leading from this spine along the sagittal suture, and termi- nating at the internal occipital protuberance. On either side of this gutter are the arborescent channels, made by the great middle artery of the dura mater. In this section we also see the internal face of the os frontis, excepting its orbitar pro- cesses ; the parietal bones; and the superior fossae in the occi- pital bone, for the posterior lobes of the brain. The Base of the cranium internally presents a very unequal surface, abounding in deep depressions, processes, and fora- mina. On its middle line, extending from before back- wards, the following objects should be remarked. The fora- men coecum at the front of the crista galli: The crista galli: And, at either side of it, the ethmoidal gutter, perforated with holes. These gutters are bounded laterally by the internal margin of the orbitar processes of the os frontis, and behind by the sphenoid bone. At the fore part of the gutter is the oblong foramen for transmitting to the nose the internal nasal nerve, and about half an inch behind this foramen, in the suture with the os frontis, is the cerebral orifice of the fora- men, called the anterior internal orbitar, which leads the same SURFACES OF THE CRANIUM. 149 nerve from the orbit. Immediately behind the ethmoidal fossae the sphenoid bone presents a plane surface, upon which are placed the olfactory nerves and the contiguous part of the brain. Behind this plane is the fossa, running from one optic fora- men to the other, for lodging the optic nerves. Behind this again is the sella turcica or pituitary fossa, bounded at its two anterior angles by the anterior clinoid processes, and behind by the posterior clinoid process. Posterior to the latter is a plane square surface of the sphenoid bone, continu- ous with the internal surface of the cuneiform process of the os occipitis. On the latter is the depression called basilar gutter, for receiving the medulla oblongata, and which is bounded below by the great occipital foramen. From this foramen to the internal occipital protuberance, proceeds the inferior limb of the occipital cross. On each side of the ethmoidal bone is a convex surface, formed by the orbitar processes of the os frontis and the little wings of the sphenoid bone, for lodging the anterior lobes of the brain. This surface is terminated behind by the rounded edge of the little wings, which is received into the fissure between the anterior and middle lobes of the brain. Just anterior to this edge is the fronto-sphenoidal suture. On each side of the sella turcica are the middle fossae of the base of the cranium. They are very wide externally, where they are bounded by the squamous portions of the temporal bones, but narrow internally, where they are bounded by the pituitary fossa. The little wings of the sphe- noidal bones terminate them in front, and form there a cres- centic edge hanging over their cavity. Their posterior mar- gin is the superior ridge of the petrous bone. This bone is placed very obliquely inwards and forwards, and its point almost reaches the posterior clinoid process. At the anterior part of the fossa is the sphenoidal fissure, or the foramen mag- num of the sphenoidal bone. Just above the base of this fissure is the foramen opticum, partially concealed by the anterior clinoid process. Just below the base of the fissure is the 150 SKELETON. foramen rotundum. At the point of the petrous bone, by the side of the posterior clinoid process, is the internal orifice of the carotid canal. On a line with the latter, exteriorlv, *s the foramen ovale. Two lines behind the latter is the fora- men spinale. The groove formed by the middle artery of the dura mater, may be traced from the foramen spinale along the anterior margin of the squamous bone. Near the upper part of this bone the groove bifurcates; the larger channel runs upwards into a groove on the tip of the great sphenoidal wing, into the principal groove of the parietal bone, which commences at the temporal angle of the latter. The smaller groove runs horizontally backwards, and just above the base of the petrous bone is continued also into the parietal bone. On the front of the petrous portion may be seen the Hiatus Fallopii. The sphenoidal suture runs through this fossa, in the examination of which, the recep- tion of the spinous process of the sphenoid bone, between the squamous and petrous portions of the temporal, will be rea- dily understood. On each side of the foramen magnum occipitis are the two posterior fossae of the base of the cranium, formed by the posterior faces of the petrous bones, the angles of the mas- toid portions of the temporal bones, and by that surface of the occipital bone below its lateral gutters. These two fossae are very partially separated by the inferior limb of the occi- pital cross. The lambdoidal suture traverses these fossae. At the junction between the petrous bone and the basilar process of the occipital, in the course of the suture, is a groove for the inferior petrous sinus. The groove conducts to the posterior foramen lacerum, which has a small part separated from it by the little spine of the petrous bone, which, with the assistance of the dura mater, forms a distinct foramen for the eighth pair of nerves. The posterior foramen lacerum being common to the temporal and occipital bones, is occa- sionally much larger on the right than on the left side ; in which case, the groove that leads from it along the angle of the temp6ral bone, the inferior corner of the parietal and the SURFACES OF THE HEAD. 151 horizontal limb of the occipital cross is also larger. Above the foramen lacerum are the meatus auditorius internus and the internal orifice of the aqueduct of the vestibule. Between the for. lacer. and for. mag. occip. is the anterior condyloid foramen. The two posterior fossae of the base of the cranium contain the cerebellum. SECT. IV.—OF THE EXTERNAL SURFACE OF THE HEAD. Anatomists, of modern times, consider the external sur- face of the head as forming or representing three ovals and two triangles, each of which constitutes a region. The first oval is the whole superior convex part of the cranium, or in other words, the external surface of its vault. The second oval is formed by the inferior part of the face, and of the cranium. The third oval is formed by the lower front part, of the os frontis, and by the face. Each side of the head forms one of the triangular regions. The superior region is so simple, and its parts have been so closely sketched, that it is unnecessary to repeat the de- scription. The inferior region or oval, extends from the chin to the occipital protuberance, and is bounded in its trans- verse diameter by the superior crescentic ridges of the os occipitis, by the mastoid processes, and by the rami and base of the lower jaw. This region is subdivided into palatine, guttural, and occipital sections or regions. The Palatine Region or section, is formed by the superior maxillary and palate bones above, and by the inferior maxil- lary bone laterally and below. It is a deep fossa, the cir- cumference of which is represented by the letter U, the open part being behind. The whole upper surface of the palatine region, presents a number of small rough elevations and fossa;, for the attachment of the lining membrane of the mouth. This surface is divided into two equal parts by the long palate suture, which is crossed at its posterior part by 153 SKELETON. the transverse palate suture. The posterior margin of the hard palate is concave on each side of the mouth; from it is suspended the soft palate. The point in the centre of this margin gives origin to the azygos uvulae muscle. The foramina on this surface, are the anterior palatine or foramen incisivum, in the long palate suture just behind the incisor teeth ; and on either side, behind, between the palate and pterygoid portions of the palate bone, bounded exteriorly by the upper maxillary, is the posterior palatine foramen. About one or two lines behind this, is another foramen, in the base of the pterygoid portion of the palate bone, through which pass fibrillar, of the same nerve that occupies the posterior palatine foramen. The posterior palatine foramen, also, transmits an artery to the soft palate, the mark of whose course may be seen at the base of the alveolar pro- cesses for the molar teeth. The depth of the palatine fossa depends on the state of the teeth. When they are removed by old age and the alveolar processes also; what was palatine fossa, is almost a plane surface, and in many instances of extreme old age, entirely so. The separation from the nose is also extremely thin, and not unfrequently imperfect. The transverse diameter of the mouth is much decreased, in consequence of the ab- sorption of the alveolar processes taking place, from the outside towards the inside. The internal surface of the lower jaw has been sufficiently described in the account of that bone. The second or Guttural Section of the inferior region of the head, is bounded anteriorly by the pterygoid fossae and openings of the nose, and behind by the mastoid and condy- loid processes. It consists, consequently, in one part, which is horizontal, and in another which is vertical. In regard to the horizontal portion, its inequalities, processes, and fossa, have been already stated. The relative position of its fora- mina cannot, however, be studied except in the united bone. The following rules will afford some assistance in determin- ing their position, even on the living body. SURFACES OF THE HEAD. 153 V line passing from the anterior margin of one mastoid process to the corresponding point of the other, will subtend the stylo mastoid foramina, and the posterior margin of the foramina lacera; it will also touch the base of the styloid processes, and cut into halves the condyles of the occiput. A line three-eighths of an inch in advance of this, will indicate the posterior margins of the glenoid cavities, and cut in half the inferior carotid orifices or foramina, and touch the ante- rior margins of the anterior condyloid foramina. Another line, one-fourth of an inch in advance of the latter, will cut through the centre of the glenoid cavity, and subtend the styloid process of the sphenoid bone, and the bony orifice of the Eustachian tube in the Temporal bone. A line passing between the external ends of the tubercles of the temporal bones, will subtend the foramina ovalia and the foramina lacera anteriora. The foramen spinale is about equidistant from the last two lines. The foramen lacerum anterius, being at the point of the petrous bone, is occasioned by the latter not filling up the space between the sphenoidal and cuneiform bones. The de- ficiency is supplied in the recent state by cartilage. Pre- cisely opposite to the point of the petrous bone, is the poste- rior orifice of the foramen pterygoideum. The vertical portion of the guttural region presents the posterior orifices of the nostrils, separated from each other by the vomer. On each side are the pterygoid processes of the sphenoid bone, and above is its body. The pterygoid fossa, formed between the external and internal process, and the long unciform termination of the latter, with the broader and shorter termination of the former, will be observed. The guttural region of the base of the head, is formed by the cuneiform process of the os occipitis-in the centre; by the inferior face of the petrous bones laterally and behind; by the body and great wings of the sphenoid bone laterally and in front; and by the several bones contributing to the orifice of the posterior nares. vol. i.—i 154 SKELETON. The Occipital Region of the base of the head, placed im- mediately behind the other, may be considered to include the mastoid processes, and the foramen magnum occipitis, and to be bounded behind by the tuber of the occiput and its su- perior transverse ridges. Its marks have been sufficiently dwelt upon, in the description of the os occipitis. On the side of the head the arch formed by the malar bone and the zygomatic process of the temporal, forms a verj conspicuous feature. The anterior abutment of this arch is formed by the greater part of the malar bone, and a consi- derable portion of the malar process of the superior maxil- lary. The posterior abutment is formed by the root of the zygomatic process of the temporal bone. Its superior mar- gin is thin, for the insertion of the temporal aponeurosis: the inferior margin is thick, and is divided by a projection in its middle, into an anterior and a posterior surface, marking the origins of the two portions of the masseter mus- cle. There is a very considerable vacancy between the zygoma and the side of the head, occupied by the coronoid process of the lower jaw, the temporal and the external ptery- goid muscles. The coronoid process is just within the zygo- matic arch, and the tip rises three or four lines above its inferior margin. The large fossa within the zygoma is the temporal. All that portion of the side of the head beneath the ridge leading from the external angular process of the os frontis, and run- ning along the middle of the parietal bone, is tributary to the temporal fossa. The bones, therefore, which form it, are the frontal, the parietal, the temporal face of the great wing and of the external pterygoid process of the sphenoid bone, and the posterior face of the superior maxillary and malar bones. The arrangement of the squamous suture is well seen in this fossa, also the junction of the pterygoid bone with the parietal and frontal, by the overlapping of the great wing of the former. At the inferior part of the latter, is the NASAL CAVITIES. \55 pointed process, from which one head of the external ptery- goid muscle arises. At the bottom of the temporal fossa there is a narrow slit partitioned from the nose by the nasal plate of the palate bone. This slit, from its position, is called the pterygo- maxillary fossa. It is triangular, the base being upwards and the point downwards. The base reaches to the bottom of the orbit. From the base there leads into the nose the spheno palatine canal, for transmitting the lateral nasal nerve and blood vessels. Externally to this foramen, and somewhat above it, is the foramen rotundum for the upper maxillary nerve. On a level with the spheno palatine canal, and run- ning horizontally through the base of the pterygoid process, is the pterygoid foramen for the nerve of the same name. Running vertically downwards from the angle of the pterygo- maxillary fossa, is the posterior palatine canal for trans- mitting the nerve and artery of the same name. The upper part or base of the pterygo-maxillary fossa is conti- nuous with a large fissure in the bottom of the orbit called the spheno-maxillary. SECT. V.—OF THE NASAL CAVITIES. The nose consists of two large cavities or fossae, in the middle of the bones of the upper jaw, and of a very irregular surface. They are separated from one another by a vertical septum, consisting in the vomer and in the nasal lamella of the ethmoid bone. This septum presents a surface which is perfectly plane, with the exception, that in some subjects it is slightly convex on one side, and concave on the other. It is deficient in front. The upper part of either nostril is formed by the cribri- form plate of the ethmoid bone, in front of this the surface is very oblique, being made by the os nasi, posteriorly there is a vertical gutter on the body of the sphenoid bone, in the middle of which is the orifice of the sphenoidal cell. The distance between the cellular part of the ethmoid and the 156 SKELETON. septum is not more than three lines. The double row of fora- mina in the cribriform plate is very well seen, also the fora- men at its anterior part for transmitting the nasal branch of the ophthalmic nerve ; the groove formed by the latter on the posterior face of the os nasi is very distinct also. The bottom of either nostril, called its floor, is formed by the palate process of the superior inaxillan and palate hone : it is somewhat concave, and about half an inch wide, its width however is not uniform, as it is sometimes widcr or narrower in front than it is in the middle. In it is seen the upper orifice of the foramen incisivum at the anterior point of the vomer. The external or orbitar surface of the nasal cavity is veiy irregular, presenting a number of projections and fossae, over which the Schneiderian membrane is displayed. It is formed by the upper maxillary, the ethmoid, the unguiform, the palate, the nasal, the lower spongy, and the sphenoid bones. In the middle of the posterior part of the ethmoid is the upper mea- tus of the nose, a deep fossa, bounded above by the cornet of Morgagni, and receiving the contents of the posterior eth- moidal cells, by one or more orifices. At the posterior ter- mination of this fossa is the spheno palatine foramen. The middle spongy bone forms the lower boundary of the ethmoid; between it and the lower spongy or turbinated bone, is the middle meatus of the nose, a fossa of considerable size, but of unequal surface. At the fore part of the middle meatus is a vertical projection, formed by the ductus ad nasum and lachrymal canal. Just behind this ridge, is an interval be- tween it and the anterior part of the ethmoid, through which the os unguis may be seen. When the superior spongy hone is broken off, immediately beneath its anterior part a chan- nel obliquely vertical, is seen in the ethmoid, which leads to the frontal sinus, through the anterior ethmoidal cell. This cell from its peculiar shape and function is called infundibu- lum. Behind this oblique channel is another oblique chan- nel, parallel, but smaller; in which several orifices may be found of the anterior ethmoidal cells. The anterior channel has, indeed, for the ethmoidal cells other orifices besides the ORBITS OF THE EVES. 157 iufundibulum, which are smaller, and below the latter. It is bounded in front by a sharp, thin ridge of the ethmoid, the lower extremity of which contributes to close the large opening into the sinus maxillare. Commonly about the middle of the middle meatus of the nose, but varying very much in different subjects, is the ori- fice of the sinus maxillare. Its precise situation and direc- tion arc so very uncertain, that its orifice is found with some difficulty in the living state, in great numbers of persons. Not unfrequently I have seen this orifice high up, under the anterior extremity of the middle spongy bone. The inferior meatus of the nose is bounded above by the lower spongy hone, and below by the palate processes. It extends the whole length of the nostril. Its transverse dia- meter is not so great as that of the upper meatus, and varies according to the development of the spongy bone, in different individuals. At the anterior part of this meatus above, is the orifice of the ductus ad nasum, Which communicates with the orbit of the eye. The nostril presents an increased width anterior to the points where the spongy bones cease, this space is bounded on the orbitar side by the nasal bone, and the nasal process of the upper maxilla. There is an increase of transverse diameter also at the posterior part of the nostril, behind the points where the spongy or turbinated bones cease. This space is bounded externally by the nasal plate of the palate bone, and by the internal pterygoid process. The posterior nares, or orifices of the nostrils, are oval, and arc completely separated by the posterior margin of the vomer. In the dried skeleton, on the contrary, the anterioff nares have a common orifice, from the deficiency of the bony septum between them. SECT. VI.—ORBITS OF THE EYES. The orbits of the eyes are the conoidal cavities in the face, presenting their bases outwards and forwards, and their 158 SKELETON. apices backwards, so that the diameter of either orbit, if continued, would decussate that of its fellow in the pitui- tary fossa. Seven bones form the orbit, the os frontis, the os malae, the maxilla superior, the os planum, the os unguis, the os sphenoides, and the os palati. Its cavity is somewhat quadrangular, besides being conoidal. The angles are par- ticularly well marked, in most subjects, at its base or orifice ; which resembles an oblong, having its long diameter in some persons placed almost horizontally, and in others obliquely downwards and outwards. Immediately within the orifice the cavity is enlarged, owing to the projection of the super- ciliary ridge, and the elevation of the anterior inferior mar- gin of the orbit, so that the greatest diameter is there rather vertical than horizontal. From this point the orbit decreases gradually in size to the sphenoidal fissure, which forms its apex. The internal walls of the two orbits are nearly parallel, inconsequence of the cuboidal figure of the os eth- moides, which is placed between them. The superior face or roof of the orbit is triangular and concave; it is very thin, and presents but a slight septum between the eye and the brain. Almost the whole of it is formed by the orbitar process of the os frontis, its point only being made by the little sphenoidal wing. The depression for the lachrymal gland, at its external anterior part, is very perceptible. The trochlea for the superior oblique muscle of the eye, is also well seen about three quarters of an inch above the point of the internal angular process of the os frontis. Just at the outer side of this depression is the fora- men or notch for the frontal artery and nerve. The optic foramen may also be seen very readily passing through the little wing of the sphenoid bone. The inferior face or the floor of the orbit is also triangular and concave, and is formed by the orbitar process of the up- per maxillary bone principally ; being assisted, however, at its anterior external margin, by a portion of the malar hone ; and at its point behind, by the orbitar process of the palate ORBITS OF THE EYES. 159 bone. The latter cannot be seen very distinctly in the arti- culated bones, owing to its great depth in the orbit; but, wnen the external side of the orbit is removed with a saw, its position is placed in an interesting light. The floor of the orbit is thinner than its roof, and forms a very slight separation from the maxillary sinus. It is terminated behind by the spheno-maxillary fissure, a large slit which, com- mencing at the base of the sphenoidal fissure, separates the great w ing of the sphenoidal bone from the ethmoidal, the palate, and the upper maxillary bones. This fissure runs obliquely outwards, so as to have its external extremity ter- minated by the malar bone. Near the external extremity is seen the commencement of the infra-orbitar canal, for trans- mitting the superior maxillary nerve and artery. The external face of the orbit is also triangular, and very oblique. It is formed by the malar bone, and by the orbitar face of the great sphenoidal wing. It is defined below by the spheno maxillary fissure, and above by the suture which unites the frontal to the malar, and to the great wing of the sphenoidal bone. It is terminated at the bottom of the orbit by the sphenoidal fissure. The internal face of the orbit is an oblong square, nearly parallel, as mentioned, with the corresponding face of the other orbit. It is formed principally by the orbitar face of the ethmoid, called the os planum, but at the apex of the orbit a small portion of the body of the sphenoid bone con- tributes to it, and anteriorly is the os unguis. It is bounded behind by the sphenoidal fissure, in front by the lachrymal ridge on the nasal process of the upper maxilla, and above and below by the upper and lower ethmoidal sutures. In the upper of these sutures there are generally two, sometimes three foramina, the anterior of which transmits an artery, a vein, and a nerve, to the nose, the posterior transmits, also, an artery and a vein to the same. The lachrymal fossa is well worthy of attention, it is seen 160 SKELETON. to commence small at the upper part of the os unguis, and to increase in size till it is formed into a complete canal, lead- ing to'tire tlose, by the upper maxillary and the inferior spongy bones. The direction of the canal is almost verti- cally downwards, inclining very slightly backwards. It was stated, that the fossa in the fore part of the os unguis is sometimes supplanted by the increased breadth of the nasal process, a fact of some importance to an operator for fistula lachrymalis. SECT. VII.—OF THE FACE, TOGETHER WITH SOME RE- MARKS ON THE FACIAL ANGLE, AND ON NATIONAL PECU- LIARITIES. The anterior oval of the head extends from the frontal protuberances to the base of the lower jaw, and from the malar bone of one side to the malar of the other inclusively. This oval is marked off into two symmetrical or equal halves by the vertical suture, which unites the bones of the opposite sides of the face. In the infant the frontal protuberances are always well marked from their being the centres of ossification for the two halves of the os frontis, in the adult they are frequently not raised above the common level of the bone. The super- ciliary protuberances just above the internal half of the su- perciliary ridges, are generally somewhat prominent, but they vary very much in this respect in different individuals. Between these ridges the frontal bone is sometimes raised into a vertical elevation continuous with the dorsum of the nose, this is more properly the nasal protuberance. It is more frequently seen in young persons. The nose, or pyramidal convexity, formed by the nasal processes of the superior maxillary, and by the nasal bones, is concave above7" and extremely prominent below. The prominence of it depends upon the development of the ossa nasi. I have frequently seen the latter curtailed to about one-half, and even one-third, of their usual breadth, and also THE FACE. 161 diminished in length ; which is followed by an unusual flat- ness of the nose; the peculiarity had been presented to me till lately only in Africans, but since then I have also met with it in European skulls : it is, however, much more un- common in the latter. The anterior orifice of the nose is cordiform, the ba.se being below ; the centre of the base is marked by a rough point, called the anterior nasal spine. The cheek bones form, on either side of the face, a con- siderable prominence, depending much upon the length of the malar process of the upper maxillary bones. In savage tribes, this prominence is a characteristic trait frequently, and may depend upon the greater development of the upper maxillary sinuses, probably from the more frequent or more intense employment of the organ of smelling. The elevation of the cheek is always conspicuous in emaciated subjects, from the fat around its base being absorbed.' The alveolar processes with the teeth produce, in certain subjects, a very conspicuous projection in the face, varying, however, considerably in different individuals, and in differ- ent tribes of human beings. There is but little doubt of the organization of some men being more coarse and animal than that of others, even in members of the same family. The cir- cumstance occasionally manifests itself by unusually large and long teeth, and by alveolar processes of corresponding dimen- sions. Savage nations have almost invariably this peculiarity, which is kept up among them, not only by hereditary influence from father to son, but also by the actual habits of the indivi- dual being productive of, and favourable to, this arrangement It would be interesting to know whether, from their articles of food generally being harder to masticate than such as are used by civilized people, they do not contribute to, or even produce a greater development in the organs of mastication. Analo- gy is in favour of the opinion, because the arms or the legs are always developed in proportion to the vigour and fre- quency of the exercise to which they are put. Ploughmen have large legs. Blacksmiths have large arms. Persons VOL. I.—X 162 SKELETON whose habits of exercise do not call into action any part of the body to the exclusion of other parts, have finer and more graceful forms than labourers. It is therefore pro- bable that the ease and gracefulness of movement, said to mark the polished and accomplished man of fashion, depend upon the harmonious action of his whole frame, derived from this proportionate development of all its parts. Besides the influence of exercise upon the organs of mastication, the pas- sions or faculties of the mind not unfrequently manifest them- selves there. Individuals of unusual ferocity and savage- ness have frequently large teeth and alveolar processes. The gnashing of the teeth has, in all ages, been considered one of the most striking signs of anger. While speaking of these indications of man in a savage and uncultivated state, it will be understood that I allude to such tribes as are engaged in the chase, and in other active modes of subsistence, and whose habits are not settled down into the agricultural or pastoral condition. It is quite pos- sible for one in the latter situation to be equally uninstruct- ed, on every point of mental improvement, and to be much inferior in capacity, to one of the former; yet his articles of food, and the sensations and passions in which he indulges, will give no very prominent outline to his face, but only mark it by the general expression of dulness and ignorance. The outline of the face is marked also by depressions or fossae. Those for the eyes and for the nose have been studied, and arrest at once the attention of the most superficial in- quirer. Immediately below the orbits are the canine fossae, formed in the centre of the front of the upper maxillae. Just above the incisor teeth of these bones is the superior incisive fossette. Below the inferior incisor teeth, on each side, also, is the inferior incisive fossette. In most adults the face projects somewhat beyond the cra- nium, but there is a considerable diversity in this respect between different tribes of human beings. C amper, who has paid much attention to this arrangement, has designated it THE FACE. 163 under the term of the facial angle, which he marks off by two straight lines. One is drawn from the lower front part of the frontal bone to the point between the roots of the in- cisor teeth of the upper jaw, the other from this latter point to the middleof the meatus auditorius externus or thereabouts. The facial angle is included between these two lines. In European, or Caucasian heads, this angle is about eighty degrees. In the Negro, or Ethiopian, it is about seventy de- grees ; and in the Mongolian or copper coloured man, about seventy-five degrees. An invariable relation is manifested between the extent of the facial angle, the capaciousness of the cranium, and the size of the nasal and palatine cavities. The nearer the an- gle approaches to a right one, the smaller is the cavity of the nose and of the mouth, and the greater is that of the cra- nium, thereby manifesting a more voluminous and intellec- tual brain. On the contrary, the more acute that the facial angle is, the smaller is the volume of brain, and the larger are the nose and mouth. This is so frequently the case, that Bichat considers it almost a rule in our organization, that the development of the organs of taste and smell, is in an inverse ratio to that of the brain, and consequently to the degree of intelligence. This, like other general rules, is subject to exceptions, in consequence of the facial angle varying in its size, from causes which have no connexion with the degree of develop- ment in the brain. • Thus an unusual prominence and thick- ness in the lower part of the os frontis, from an increased capaciousness of the sinuses, will make the facial angle ap- pear less acute. The absorption of the alveolar processes, after the loss of the teeth, will produce the same result in our measurements of the facial angle. The heads of infants, previously to the appearance and full growth of the teeth, have always the facial angle less acute than the heads of adults ; in some cases an angle of ninety degrees is presented in them. On the contrary, a growth of teeth, and conse- quently of the alveolar processes, disproportionate to the size of the body of the upper jaw, will cause the facial angle to 164 SKELETON. project very considerably even in an individual of the Cau- casian race. Similar objections may be brought against the indications of the inferior line. The fair state of this ar- gument appears then to be, that the doctrine of the facial angle, though correct in a majority of instances, has nume- rous exceptions from individual peculiarities, and that there is no tribe of human beings which does not present the facial angle in all its ranges from seventy to ninety degrees. In regard to the various configurations of the human face and stature, depending upon habits and circumstances con- tinued through a long succession of ages and generations, the following views of one,* preeminently qualified to judge, will not be uninstructive. " Although there appears to be but one human species, since all its individuals can couple promiscuously, so as to produce a prolific offspring, we yet remark in it certain he- reditary conformations, which constitute what are called races. Of them there are three which are eminently distinct in appearance; they are, the White or Caucasian; the Yellow or Mongolian; the Negro or Ethiopian.'' "The Caucasian Race, to which we belong, is distin- guished by the beautiful oval form of the head ; and it is this which has given birth to the most civilized nations, and to those which have generally ruled over the others. It has some differences in the shade of the complexion, and in the colour of the hair." "The Mongolian is known by its prominent cheek bones, flat face, narrow and oblique eyes, straight and black hair, thin beard, and olive Complexion. It has formed vast em- pires in China and Japan, and has sometimes extended its conquesl on this side of the Great Desert; but its civiliza- tion has always remained stationary." ^ Regne Animal, par M. Ie Chev. Cuvier, torn. 1. p. 94. Paris, 1817. THE FACE. 165 "TheNegro race is confined to the south of Mount Atlas; its complexion is black, its hair woolly,its skull compressed, nose flatfish; its prominent mouth and thick lips make it manifestly approach the monkey tribe; the people which compose this race have always remained in a state of bar- barism." "The race from which we are descended is called Cau- casian, because tradition and also the lineage of nations, would appear to trace it to the group of mountains situated between the Caspian and the Black seas, (on the borders of Europe,) from whence it has radiated in every direction. The people of Caucasus, as also the Georgians and Circas- sians, are considered, even at the present day, the hand- somest in the world. The principal branches of this race are distinguishable by the analogies of language. The Ar- menian or Syrian division, directed its course towards the south, and has given birth to the Assyrians, the Chaldoans, and the untameable Arabs, who, after Mahomet, were very near becoming masters of the world; to the Phcnicians,the Jews, and the Abyssinians, who were Arabian colonies; and it is very probable that the Egyptians also are descended from the same source. It is from this branch, (the Syrian) always inclined to mysticism, that the most widely extended religions have sprung. Science and literature have flourished among them occasionally, but always under fantastic forms, and with a figurative style." "The Indian, German, and Pelasgic branch, is infinitely more extended, and was divided at a much earlier period; we, nevertheless, recognise the greatest resemblance between its four principal languages ; which are, the Sanscrit, at pre- sent the sacred language of the Hindoos, and mother of all the dialects of Hindostan; the ancient language of the Pe- lasgi, which is the common mother of the Greek, the Latin, of many tongues which are now extinct, and of almost every language spoken in the South of Europe; the Gothic or Teutonic, from which are derived the languages of the North and North West, such as the German, Dutch, English, 166 SKELETON. Danish. Swedish, and their dialects; and lastly, the lan- guage called Sclav.mian, from which come those of the North East, as the Russian, Polish, Bohemian, &c." "It is this great and respectable branch of the Caucasian race, which has carried farthest Philosophy, the Arts and Sciences, and which has been for ages the depository of them." "This branch was preceded in Europe by the Celts, who came from the North, and were formerly very much ex- tended, but are now confined to the most Western parts; and by the Cantabrians, who passed from Africa into Spain, and are, at present, almost confounded with the numerous nations whose posterity has been blended in this peninsula." "The ancient Persians have the same origin with the In- dian branch; and their descendants, even at the present day, bear the strongest marks of affinity to the European nations." "The Scythian or Tartarian branch, first directed their course to the North and North East, and always led erratic lives in the vast plains of those countries; they have only left them to return and destroy the more comfortable establish- ments of their brethren. The Scythians, who, at so remote a period of antiquity, made irruptions into Upper Asia; the Parthians, who destroyed there the power of the Greeks and Romans; the Turks, who overthrew there that of the Arabs, and subjugated in Europe the unhappy remnant of the Greek nation, were swarms of this stock; the Finlanders and the Hungarians are colonies of it, in some measure astray among the Sclavonian and Teutonic nations. The North and East of the Caspian Sea, their original country, are still inhabited by people of the same origin, and speak- ing similar languages; but they are there intermixed with an infinity of other petty nations, of different origins and languages. The Tartar nation has always remained more unmixed in all that tract of country, extending from the mouth of the Danube, to beyond the Irtisch, from which they so long threatened Russia, and where they have at last been subdued by her. The Mongolians, however, in their con- THE FACE, 167 quests, have blended their blood with these people, and many traces of this intermixture are discovered principally among the Western Tartars." The Mongolian race commences to the East of this Tartar branch of the Caucasian, and prevails thence to the Eastern Ocean. Its branches, the Calmucks and Hal- kas, still nomadic or unsettled, occupy the Great Desert. Thence have their ancestors, under Attila, under Gen- gis, and under Tammerlane, spread far and wide the terror of their name. The Chinese come from this race, and are not only the most anciently civilized of it, but indeed of any nations yet known. A third branch, (the Montchoux) has recently conquered China, and continues to govern it. The Japanese and Coreans, and almost all the hordes which ex- tend to the North East of Siberia, under the domination of Russia, belong also to it in a great measure. If we except a few Chinese literati, the whole Mongolian race is univer- sally addicted to the different sects of the worship of Fo." "The origin of this great race appears to have been in the Altay Mountains,* as ours was in the Caucasian; but it is impossible to follow so well the clew of its different branches. The history of those wandering people, is as fu- gitive as their establishments; and the records of the Chi- nese, from being confined to their own empire, afford us hut short and vague accounts of their neighbouring nations. The affinities of their languages are also but too little known to guide through this labyrinth." "The languages of the north of the peninsula beyond the Ganges, and also that of Thibet, bear some affinity to the Chinese, at least in their monosyllabic nature, and the peo- ple who speak them are not without traits of resemblance to the other Mongolian nations ; but the south of this peninsula is inhabited by the Malays, a much handsomer people, whose race and language are spread over the coasts of all the islands * A range in the North of As:a, about rOOO miles long 168 SKELETON. of the Indian Archipelago, and have occupied almost all those of the Southern Ocean. On the largest of the former, espe- cially in the uncultivated and savage parts, we find other men, who have woolly hair, black complexion, and negro visage, and who are all extremely barbarous. The most know n are the Papuas, a name by which they may be gene- rally denominated." " It is not easy to refer either the Malays or Papuas to any one of the three great races; but can the former be plainly distinguished from their neighbours, the Caucasian Hindoos on one side, and the Mongolian Chinese on the other ? We must confess that we do not find them to pos- sess sufficient characteristics to enable us to answer this question. Are the Papuas negroes, who formerly straggled along the Indian Ocean ? we have neither drawings or de- scriptions sufficiently clear to reply to this question." " The inhabitants of the north of the two continents, the Samoiedes, the Laplanders, and the Esquimaux, spring, according to some authorities, from the Mongolian race. Agreeably to others they are but a degenerate offspring of the Scythian and Tartarian branches of the Caucasian race." " It is impossible to refer, satisfactorily, the Americans themselves to either of our races of the old continent; and yet they have not characteristics precise and constant enough to constitute a distinct race. Their copper-coloured com- plexion is not sufficient; their hair, which is generally black, and their scanty beard, would lead us to refer them to the Mongolians, did not their well marked features, and their moderately prominent noses, oppose such an arrangement; their languages are as innumerable as their tribes, and we have yet been unable to discover either any analogies among themselves, or with those of the ancient world."* * On this subject see also Lectures on the Physiology, Zoology, and Natu- ral History of Man, by W. Lawrance. London, 1822. Dctionnaire des Sciences Med. tome XXI. Paris, 1817. Histo're Natnrelle de L' Homme, par Lacapede. Paris, 1821. Blumenbach de Variet. gen. hum. nat. 1794—also Decades, 1790—1814. FffiTAL HEAD. 169 «.ECT. VIII. ON THE DEVELOPMENT OF THE FCETAL HEAD. The foetal head, in the very early stages of gestation, forms an oval vesicle, constituting the greater part of the bulk of the embryo, and at this period has the face scarcely visible. The parietes of this vesicle are formed by a thin membrane consisting of two layers, the external of which is the pericranium, and the internal layer, is the dura mater. These layers adhere so closely that they cannot be accu- rately separated by the knife. About the third month of the embryo, or even earlier, os- sification may be seen at several points of the cranium, but more extensively about its base. These points are the centres of ossification, which progressively increase towards their re- spective circumferences, by the deposite of new bony matter. Generally the base of the cranium begins to ossify before the vault, and is entirely ossified at birth with the exception of a few parts, as the clinoid processes and the ethmoid bone. The following nuclei of ossification show themselves be- tween the laminae of the foetal cranium, from the third to the fourth month. One, at the anterior part, for the centre of either side of the os frontis ; one for the centre of each parie- tal bone, on the upper side of the head ; one on the side of the head below, for the squamous portion of the temporal bone ; and there are several for the occipital bone. These points extend themselves in radii, and, as the intervals be- tween the latter become wider by their divergence, new ra- dii, as observed elsewhere, are deposited between them. In some of the bones the radii, from opposite points, in the progress of ossification before and after birth, meet and coa- lesce; this occurs in the os frontis and in the os occipitis. At birth the contiguous margins of the flat bones simply approach each other but have not interlocked. These bones consist then of but one table, the edges of which are very finely serrated, and thereby show the radii of ossification. The edges are held together by the dura mater internally, and the pericranium externally, but the fissure between them is VOL. I.—Y 170 SKELETON. very obvious, and so large that it allows very readily con- siderable motion, and the mounting of one bone upon the other by slight pressure. It is always to be observed that the base of the cranium is an exception to the latter rule, both from the breadth of its articulating surfaces, and from its comparatively advanced ossification. In parturition, there- fore, the vault of the cranium, by its mobility, is adjusted to the contour of the pelvis, but the base does not yield in either of its diameters to the expulsive powers of the uterus. The latter provision, how ever inconvenient in parturition, is of the greatest consequence immediately afterwards, for without this immobility in the base of the cranium, whenever the weight of the head was thrown upon it, the pressure of the vertebral column would drive it upwards, to the injury of the brain and of the nerves proceeding from it. This resistance, it may be added, is still further assisted by the arched figure of the base of the cranium. On this subject it is not a little remarkable that even the heads of hydroce- phalic foetuses have the bones of the base fully ossified, and in contact, so as to support the weight of the head in the vertical position. Fontanels.—In consequence of the flat bones of the era- ] nium ossifying always towards the circumference, their an- gles, as observed, being the longest radii from their centres, are the last in ossifying. These angles are commonly in- complete at birth, and the membranous spaces which repre- sent them are the Fontanels. Of these there are six, two on the middle line of the head above, and two on cither side. The former afford highly important indications to the mid- wife. The anterior fontanel is the largest of all. It is at the fore part of the sagittal suture, and is produced by a defi- ciency in the angles of the parietal bones and of the conti- guous angles of the os frontis. It is quadrangular or lozenge shaped, and the anterior angle is generally longer than the others. This is remarkably the case when the sagittal suture is continued down to the root of the nose. The posterior FffiTAL HEAD. 171 fontanel is at the other extremity of the sagittal suture, and as there are only three points of bone defective there, two for the parietal bones, and one for the occipital, this suture is triangular. In many children, at birth, it is so far filled up as to be scarcely visible, the three membranous sutures however which run into it, make its position sufficiently dis- cernible by the finger. Of the two fontanels on either side, one is placed at the angle of the temporal bone where it runs up between the oc- cipital and the parietal. The other is in the temporal fossa under the temporal muscle at the junction between the parietal and the sphenoidal bones. These two fontanels are but little referred to by the accoucheur in delivery, as they are irre- gular and indistinct. The pulsations of the brain may be readily felt through the fontanels. They ossify rapidly after birth, and are frequently closed completely by the end of the first year; but if there be an accumulation of water in the ventricles of the brain they remain open for an indefinite period. The longest diameter of a child's head is from the vertex or posterior extremity of the sagittal suture to the chin, and: measures five inches and a quarter. From the middle of the frontal bone to the tubercle of the occipital are four inches, from one parietal protuberance to the other is about three inches and a half. At birth the os frontis consists most commonly of two pieces united by the sagittal suture. The parietal bone is a single piece, incomplete at its angles. The temporal bone consists of three pieces, one is the squamous, the other is the petrous, and the third is a small ring which afterwards con- stitutes the meatus externus; it is deficient in styloid and mastoid processes. The os occipitis is in four pieces, one extends from the angle of the lambdoidal suture to the upper edge of the foramen magnum ; on either side of the foramen magnum is another with the condyle growing on it, and the cuneiform process is the fourth. The ethmoid bone is carti- laginous. The sphenoidal bone is in three pieces. The body and little wings being united form one ; the great wing and |72 SKELETON. the pterygoid process, being also united, form on cither side of the body another piece. At birth there is a great disproportion in size between the cranium and face. This disproportion diminishes in the pro- gress of life, by the development of the sinuses and of the alveolar processes in the latter. At birth, indeed, there is no cavity either in the sphenoidal, the frontal, or the upper maxillary bones ; the orbitar and the palate plates are very near each other, and the rudiments of the teeth are hidde.i in the bodies of the upper and lower jaw bones. The latter consists of two pieces, united by cartilage at the chin, and its angle is very obtuse. CHAPTER IV. OS HYOIDES. The Os Hyoides is placed at the root of the tongue, within the circle of the lower jaw. It is an insulated bone, having no connexion with any other except by muscles and liga- ments. It is said, very properly, to resemble the letter U, and consists of a body and two cornua. The body is in the middle; it is the largest part of the bone, and forms nearly a semicircle. Its anterior face is convex, and its upper part is flattened by the insertion of the muscles from the lower jaw. The posterior face is concave. The cornua, one on either side, arc about an inch long, and are placed at the extremities of the body, being united to it by the interposition of cartilage and ligamentous fibres. They are somewhat flattened rather than cylindrical, and diminish towards the posterior extremities, where they ter- minate in a round enlargement like a head. At the cartilaginous junction of the cornu and body, on each side, there is a small cartilaginous body three or four THE SHOULDERS. 173 lines long, fastened by ligamentous fibres. It is frequently found ossified. This is the appendix or lesser cornu. A round ligament passes from it to the extremity of the styloid process. The texture of this bone is cancellous, with a thin lamina externally. M. Portal says, that he has found it carious from venereal contamination, in which case, the patient had been afflicted with violent sore throat and purulent expecto- ration. Sauvages and Valsalva, have met with a case where from luxation of the cornu the patient spoke with great diffi- culty. The ligament to the styloid process, is in some rare instances ossified to a considerable extent, which produces difficulty in swallowing and in talking. CHAPTER \ . OF THE UPPER EXTREMITIES. This portion of the skeleton is divided, on either side of the body, into shoulder, arm, fore arm, and hand. SECT. I.--OF THE SHOULDER. The shoulder consists of two bones, the clavicle and the scapula, and occupies the superior, lateral, and posterior part of the thorax. Its shape and position are such, that it aug- ments considerably the transverse diameter of the upper part of the trunk, taken as a whole : while the thorax alone, at this place, is actually smaller than it is below. The cla- vicle is longer, in proportion, in the female than in the male, which increases the transverse extent of the shoulder, and gives a greater space on the front of the thorax for the de- velopment of the mammae This coincidence between the 174 SKELETON" length of the shoulder and the development of the mamma, has been particularly noticed by Bichat, who says that it is almost always well marked, that very rarely a voluminous bosom reposes on a small pectoral space, or a small bosom is found upon a large pectoral space. In the male, on the con- trary, this diameter of the trunk is increased principally by the breadth of the scapula, which, from its position on the thorax, and its great size, gives the bulky appearance to this part. It is evident that these modifications in the frame work of the shoulder, is connected with the natural destinations of the two sexes. In man the increased size of the whole skeleton, and the greater development of the muscular sys- tem, indicate that he was intended for more laborious exer- tion than the female. In woman the length of the claviclels adverse to its strength, and it is indistinctly marked by muscu- lar connexions ; whereas, in man it is short, strongly marked, and large. Anatomists who are fond of extending such com- parisons, say, also, very justly, that the pubes, which per- form the same office for the lower extremities, that the clavi- cles do for the upper, that of keeping the two apart, are, in the female, both smaller and longer than in the male; that their shape is not so favourable to strength or locomotion, and has a special view toward the lodgement of the genital organs, and the passage of the child. The thorax and the shoulder are connected by a reciprocal development, both being indicative, when large, of a robust and vigorous constitution, and when small, of a weakly one. As both of these parts are acted on by the same muscles, the necessity of this coincidence is sufficiently apparent. The height of the shoulder depends upon the scapula alone, its elevation, therefore, is greater in males and in vigorous per- sons generally, than in females and in weakly individuals. The direction of the shoulder is such, that the articular face of the scapula for the os humeri, looks outwards, thereby proving that the quadruped position in man is unnatural; for by it, the weight of the fore part of the trunk is directed upon the back part of the capsular ligament of the joint, instead of upon the glenoid cavity, as in quadrupeds. This circum- THE SHOULDERS. 175 stance, and many others, show that the natural intention of the upper extremities in the human subject, is to seize upon objects and not to maintain the horizontal position. Of the Shoulder Blade, (Scapula.) The scapula is placed upon the posterior superior part of the thorax, and extends from the second to the seventh rib, inclusively; its posterior edge is nearly parallel with the spinous processes of the vertebra} and not far from them. Its general form is triangular. It therefore presents two faces, of which one is anterior, and the other posterior,— three edges, of which one is superior, another external, and the third internal or posterior—and three angles, of which one is superior, another .inferior, and the third exterior or anterior. The posterior face of the scapula or its dorsum is some- what convex, when taken as a whole, and is unequally divided by its spine into two surfaces or cavities, of which the lower is twice or three times as large as the upper. The spine is a very large process that begins at the posterior edge of the bone, by a small triangular face; rapidly increases in its ele- vation, and running obliquely towards the anterior angle, ceases somewhat short of it; it is then elongated forwards and upwards, so as to overhang the shoulder joint, and to form the acromion process. The cavity above the spine is owing principally to its elevation, and is called the fossa supra-spinata; it is occupied by the supra-spinatus muscle. The cavity below the spine is the fossa infra-spinata; it is for the infra-spinatus muscle: below it is bounded by a rising of the external margin of the bone. The middle of this fossa presents a swell or convexity, which is a portion of the gene- ral convexity presented by the posterior face of the bone. The spine of the scapula is always prominent in the outline of the shoulder, and has a well secured base along the whole of its attachment to the bone, to where it terminates in the acromion process. It leans upwards, and from the in- creased breadth of its summit, is concave both above and 176 SKELETON. below. The summit itself is somewhat rough, and has in- serted into its superior margin the trapezius muscle, while the inferior margin gives origin to the deltoid. The little triangular face at the commencement of the spine is made by the tendon of the trapezius muscle gliding over it. The acro- mion process arises from the spine by a narrow neck, is tri- angular, nearly horizontal, and overhangs the glenoid cavity, being elevated about one inch above it. It is slightly con- vex above, and concave below; the external and the internal margins are the longest. The posterior margin is conti- nuous with the inferior edge of the spine : and the internal is on a level with the clavicle. At the fore extremity of the internal is a small, oval, articular face, by which the acromion unites with the clavicle. The margins of the acromion, with the exception of the internal, are rough, and give origin to the deltoid muscle. The anterior or costal face of the scapula is concave, and obtains the name of the sub-scapular fossa. It is occupied by the sub-scapular muscle, the divisions of which, by leaving deep interstices between them, produce corresponding ridges upon the bone, that run obliquely upwards and outwards. Along the whole posterior margin of the costal face, is in- serted the serratus major anticus. The posterior or vertebral margin of the scapula is the longest of the three, and is called the base. It is not per- fectly straight, but somewhat rounded, especially above the spinous process ; and has there varied degrees of obliquity in different persons. This margin, below the spine, receives the rhomboideus major muscle, and above the spine, the levator scapulae ; at the part between the other two, the rhomboideus minor is inserted. The external or axillary margin of the scapula, also called the inferior costa, is much the thickest of the three. A su- perficial fossa, beginning about two inches from its inferior extremity and running up to the neck of the bone, lodges the THE SHOULDERS. 177 teres minor muscle. On the exterior face of the inferior angle is a flat surface from which the teres major muscle arises. At the fore part of this surface the inferior costa is elongated into a kind of process. Just below the glenoid cavity is a small ridge for the origin of the long head of the triceps muscle. The superior margin or costa of the scapula, is the shortest and thinnest of the three, and is terminated in front by a notch betw een it and the coracoid process. The notch is con- verted into a hole by a ligament, in the living state, and through it pass the upper scapular nerve and blood vessels. The glenoid cavity for articulating with the os humeri, supplies the place of the anterior angle of the scapula. It is very superficial, and ovoidal, with the small end upwards. Just at the upper end is a small flat surface, from which the long head of the biceps arises. The glenoid cavity is fixed on the cervix, as it is called, at which a general increase in the thickness of the bone occurs, in order to give a strong foundation to this cavity. From the superior part of the cervix arises the coracoid process, the base of it being bounded in front hy the glenoid cavity, and behind by the notch. The base rises upwaids and inwards for half an inch, and what remains of the process then, runs horizontally in- wards and forwards, to become smaller, and terminate in a point. This point is advanced beyond the glenoid cavity, about an inch from its internal margin. The upper sur- face of the coracoid process is rough and undulated ; below it is concave, forming an arch, under which passes the subsca- pularis muscle. On the clavicular side of its base is a tube- rosity, from which arises the conoidal ligament. The ex- tremity is marked hy three surfaces, the interior is for the insertion of the pectoralis minor, the middle for the origin of the coraco-brachialis, and the external for that of the short head of the biceps. The acromial margin of the cora- coid process gives origin to the triangular ligament of the vol. i.—z 178 SKELETON. scapula, which is inserted into the acromion just below the face for the clavicle. The scapula is composed of cellular and compact sub- stance. The two lamina of the latter are in contact, in the fossa supra-spinata and infra-spinata, from which cause the bone is diaphanous at these points. Of the Clavicle, (Clavicula.) The Clavicle is a long bone, situated transversely at the upper front part of the thorax, and extends from the superior extremity of the sternum to the acromion of the scapula. It is cylindrical in its middle third, flattened at its external, and prismatic or triangular at its sternal extremity. It is more crooked and robust in man than in woman, and differ- ent individuals present it under considerable varieties of cur- vature. The sternal, two-thirds of it, is convex in front, and concave behind, while the humeral third is concave in front, and convex behind, this double curvature induces ana- tomists to compare it with the letter S, though it is never so crooked. We have to consider its superior and inferior face, its an- terior, and a posterior edge, and the two extremities. The superior face is smooth, and does not present any marks of importance excepting a depression near the sternum, for the origin of the sterno-cleido mastoid muscle. The inferior face, near the sternal end, has a rough surface, to which is at- tached the costo-clavicular or rhomboid ligament: near its humeral extremity is a rough tubercle for the attachment of the coraco clavicular or conoid ligament. Between those two points, a superficial fossa is extended for lodging the sub- clavius muscle. The sternal two-thirds of the anterior mar- gin is marked by the origin of the pectoralis major, it is there thick, the other part of this margin is thinner, and gives origin to the deltoid muscle. The posterior margin presents near its middle, one or more foramina for the nutritious ves- sels. The triangular internal end of the clavicle is unequal where it joins the sternum, and is elongated considerably at THE ARM. 179 its posterior inferior corner. The external flat end presents at its extremity a small oval face, corresponding with that on the acromion scapulae. This bone is very strong from the abundance of its con- densed lamellated structure, but like other round bones, the cellular matter predominates at its extremities. sect. n.—of the arm, (Os Humeri.) The arm extends from the shoulder to the elbow, and has but one bone in it, the os humeri. The latter in its general appearance is cylindrical, with an enlargement of both ex- tremities; the superior end presents a general swell, while the inferior is flattened out. The superior extremity of the os humeri, which is also called its head, is very regularly hemispherical, and has its axis directed obliquely upwards and backwards, in order that it may apply with more facility to the glenoid cavity of the scapula. The base on which the head reposes is termed neck, it is not more than four or five lines long, and is marked off by a superficial furrow, surrounding the bone. This furrow is more conspicuous above, where it separates the head from two knobs called the tuberosities. One of these tuberosities, the external, is much larger than the other, and bears on its upper face the marks of the ten- dinous insertion of three muscles. The most internal mark is for the supra-spinatus scapule, the middle for the infra- spinatus, and the external or posterior for the teres minor. The smaller tuberosity is internal, and placed on a line with the coracoid process, while the other is beneath the acromion; it has but one mark, and that is on its upper face, for the tendinous insertion of the sub-scapularis muscle. The two tuberosities are separated by a deep fossa, named bicipital, from its lodging the tendon of the long head of the biceps muscle. This fossa is continued faintly for some inches down the os humeri, its lower part being bounded externally by a rough ridge, indicating the insertion of the pectoralis 180 SKELETON. major, and internally by another ridge, not quite so strong or rough, indicating the insertion of the teres major and la- tissimus dorsi. The body of the os humeri is the part extended between its extremities. The superior half presents a more cylindrical appearance than the inferior, which is rather triangular. On the middle of the bone externally, an inch or two below the insertion of the pectoralis major, exists a triangular ele- vation into which the deltoid muscle is inserted. At the in- ternal margin of the bone and on a line with the latter, is the insertion of the coraco brachialis muscle ; and between the two is the orifice of the canal for the nutritious artery. The front of the os humeri, in its lower half, is flattened on each side down to its inferior end, on these surfaces is placed the brachialis internus muscle. On a line with the posterior face of the greater tuberosity and a little below it, an eleva- tion is formed for the origin of the second head of the triceps extensor cubiti. The posterior face of the bone is flattened from this point dow n to its lower extremity, and accomo- dates the last named muscle. The articular surface for the elbow joint is very irregu- larly cylindrical. The part that joins the radius, presents itself as a small hemispherical head placed on the front of the bone, and with its axis looking forwards. Just above it in front, is a small depression for the head of the radius in its flexions. The surface which is in contact with the ulna, is more cylindrical, but still irregularly so, for its middle is depressed while the margins are elevated ; the internal mar- gin being much larger than the external. The lesser sig- moid cavity is just above the front of the ulnar articular sur- face, and receives the coronoid process. The greater sigmoid cavity is in a corresponding place behind, and receives the olecranon process ; the bone which separates these cavities is very thin, sometimes it is even deficient. The external condyle is just above the radial articular THE FORE-ARM. 181 surface; it is continuous wTith a ridge of three or four inches long, forming the external margin of the bone, and from it and the ridge together, arise the extensor muscles of the fore arm and hand. The ridge itself is bounded above by a small spiral fossa, descending downwards and forwards, made by the spiral artery and the muscular spiral nerve. The inter- nal condyle is placed just above the internal margin of the ulnar articular surface, it is much more prominent and dis- tinct than the external, and may be readily felt beneath the skin. A ridge also leads from it, and extends upwards as high as the insertion of the teres major, hut it is by no means so elevated as the external ridge, though it is much longer. From the internal condyle and the adjoining part of the ridge, arise the flexor muscles of the hand and fore arm. The os humeri is composed of compact and cancellated substance ; the latter predominates at the extremities, and the former in the body. SECT. III.—OF THE FORE-ARM. The fore-arm is placed between the arm and the hand, and consists in two straight bones, the Ulna and the Radius, of which the former is on the same side with the little finger, and the latter on that of the thumb. Of the Ulna. The Ulna, though nearly straight, is not wholly so. It is much larger at the upper than at the lower extremity, and in its general features is triangular. It has to be considered in its humeral and carpal extremities, and in its body. The humeral or upper extremity presents the olecranon process at its termination, the coronoid a little below and in front; the greater sigmoid cavity between the two ; and the lesser sigmoid on the radial surface of the coronoid. 182 SKELETON The olecranon process is rough on its upper face, for the insertion of the triceps muscle, and terminates in front in a sharp edge and point, which arc received into the greater sig- moid cavity of the os humeri. The coronoid process is a tri- angular, sharp ridge, much elevated, and having a large base; on the lower front of the latter is a roughness for the inser- tion of the brachialis internus muscle. The greater sigmoid cavity forms all the surface between the margins of the two processes. It is divided transversely at its bottom by a su- perficial roughness, which distinguishes the olecranon from the coronoid portion of it. Besides which a flat rising ex- ists in its vertical length, which is received into a corres- ponding depression on the os humeri. The lesser sigmoid cavity has its surface continuous with that of the greater, and presents itself as a small cylindrical concavity for receiving the side of the head of the radius. A small fossa for fatty matter exists just above it. The carpal or lower extremity of the ulna presents, on the side of the little finger, a process of variable length, the styloid, from which arises one of the lateral ligaments of the wrist. At the radial side of this process is an articular face or small head, one surface of which looks towards the wrist, and the other is in contact with the radius, being semicylin- drical. On the back of the ulna, between the styloid pro- cess and this head, is a groove for the passage of the extensor carpi ulnaris. The body of the ulna is triangular, in consequence of three ridges, which extend from the brachial to the carpal extre- mity. The most prominent of these ridges is on its radial side, and beginning a little below the lesser sigmoid cavity continues very distinct almost to the lower end; it then, how- ever, gradually subsides. From it arises the interosseal liga- ment. Within this ridge on the anterior or palmar face of the bone, is another more rounded, which, beginning at the internal margin of the coronoid portion of the greater sig- moid cavity, extends down to the styloid process. For the THE FORE-ARM. 183 greater part of its length it gives origin to the flexor pro- fundus, but just above the carpus the pronator quadratus arises from it. The third ridge begins at the external mar- gin of the olecranon part of the greater sigmoid cavity, runs in a serpentine way to the back of the little head below, and becomes indistinct at its lower part. To the upper fourth of this ridge is attached the anconeus muscle, which reposes in a hollow between it and an oblique ridge below, running from the back of the lesser sigmoid cavity. To the latter ridge is attached the supinator radii brevis muscle. On the posterior surface of the bone, just below the ole- cranon, is a long sub-cutaneous triangular face on which we lean. The three ridges of the ulna divide it into as many surfaces, which are each modified by the muscles lying upon them. The anterior surface presents, just above the middle of the bone, the canal for the nutritious artery, running obliquely upwards. The body of the ulna is compact, the extremities, and more abundantly the upper, are cancellated. Of the Raditts. The radius is shorter than the ulna, is placed on its exter- nal side, and extends from the os humeri to the wrist. It is smaller at the humeral than at the carpal extremity, and though nearly straight is somewhat convex outwardly. It is to be considered in its extremities and body. The superior or humeral extremity presents a cylindrical head, which bears all around it the marks of a cartilaginous incrustation, broader on the cubital than on the other side. The broader part plays in the lesser sigmoid cavity of the ulna, while the other is in contact with the annular ligament. A superficial fossa also exists on the upper surf; ce of this head, which receives the convexity of the articular face of the os humeri. The head of the radius is placed upon a nar- row part called the neck, of about half an inch in length. jg^ SKELETON. Immediately below the neck, on the ulnar side, is a rough protuberance for the insertion of the biceps flexor cubiti. The lower or carpal extremity of the bone, is augmented con- siderably in volume, and is flattened out transversely. The carpal surface presents a long superficial cavity, bounded ex- ternally by the styloid process, from which proceeds the exter- nal lateral ligament, and on its ulnar side, by a small cylindri- cal concavity, for receiving the lower end of the ulna. This superficial cavity is divided into two by a slight ridge in its short diameter; the division next the styloid process receives the scaphoid bone, and the other the os lunarc. At this extre- mity also a ridge exists on the front of the bone for forming the margin of the articular face, and giving origin to the capsular ligament. The posterior and external faces of the bone here, are rendered irregular by several grooves and ridges. The large groove next to the cylindrical concavity for the ulna, transmits the tendons of the extensor communis digitorum and indicator, also the tendon of the extensor major pollicis, which forms a channel somewhat distinct and on the styloid side of the groove. Next to this is another large groove for the tendons of the extensor carpi radialis brevior and longior, and on the styloid side of the radius is the third groove for transmitting the tendon of the extensor minor pollicis and of the extensor ossis metacarpi pollicis. The body of the radius is somewhat triangular, and there- fore presents three ridges. One on its ulnar extends from the bicipital protuberance to the lower end, and gives origin to the interosseous ligament; it is sharp and well marked. Another on the outer or styloid margin of the bone, which also begins at the bicipital protuberance, terminates in the styloid process. The upper part of this ridge is curved, has the supinator brevis inserted into it, and a portion of the flexor digitorum sublimis arising from it; at its lower part the pronator quadratus is inserted. A small spine is also found just above the styloid process, and into it is insert- ed the tendon of the supinator radii longus. The third ridge is on the posterior face of the radius, and, arising insen-ibly THE HAND. 185 from below its neck, is principally conspicuous in the middle third of the bone; it runs down, however, to the carpal ex- tremity, and becoming more prominent there, separates the two larger grooves from each other. This ridge is shorter, and not so elevated as the other two. These three ridges form as many surfaces to the radius, of which the anterior, augmenting gradually in its descent, affords attachment to the flexor longus pollicis above, and to the pronator quadratus below ; at its upper part is the canal, slanting upwards, for the nutritious artery. The posterior surface has the extensor muscles of the thumb and the indi- cator lying upon it. The external surface presents a rough- ness, just above its middle, for the insertion of the pronator teres; and below, it is covered by the radial extensors, which are crossed by the extensor metacarpi pollicis and the ex- tensor minor. The body of the radius is compact; its extremities are rancellated. SECT, IV.—OF THE HAND. The hand consists of carpus, metacarpus, and phalanges, and has in its composition twenty-seven bones, to which number may be added the two sesamoids. Of the Carpus. The carpus or wrist is next to the bones of the fore arm. Eight bones compose it, which are arranged into two rows, one adjoining the fore arm and the other the metacarpus: they are called first and second rows. These bones present very diversified forms and a number of articular faces, which render them difficult to be distinguished from each other. The first or antibrachial rowr has in it the os scaphoides, lunare, cuneiforme, pisiforme. The second or metacarpal row has in it the os trapezium, trapezoides, magnum, and unciforme. voi,. i.—a a 186 SKELETON. Of the Scaphoides.—This bone is on the styloid half of the end of the radius, and is distinguishable in a set by its greater length. It is convex above and concave below. The con- vexity forms only a half of its upper surface, the other half being rough, and making a knob at its extremity. The con- cavity on the lower surface is large enough to receive the end of the finger. Between the concavity and the convexity, and on the dorsal surface of the bone at its outer end, is a second convexity, of an oblong shape. Between the two convexities is a small fossa for the capsular ligament. The palmar or anterior face shows a crook in the bone. The knobbed extremity projects beyond the styloid process of the radius. The other extremity, which is narrow, joins the os lunare. Of the Lunare.—This bone is at the ulnar side of the pre- ceding, and may be distinguished by the semi lunated shape of the surface joining the scaphoides. Its upper surface is convex where it articulates with the radius; the lower face is concavely cylindrical. The ulnar side is a plane surface which joins the os cuneiforme. Its dorsal side is rather thinner than its palmar. Of the Cuneiforme or Pyramidale.—This bone is placed at the ulnar side of the last, is somewhat larger than it, and may be distinguished by its representing somewhat a trian- gular pyramid. The surface next the lunare is plane, but the other extremity, being the boundary of the wrist in that direction, is rough. Above it presents a small convexity ad- joining the surface for the lunare, whereby it enters partially into the upper wrist joint. Its inferior surface is concavo- convex, the convexity being towards the ulnar end. On its palmar side it presents a circular plane surface for the os pisiforme. Of the Pisiforme.—This bone is placed on the front or palmar surface of the last, and may be distinguished by its being smaller than any other in the carpus, by its spheroidal THE HAND. 1S7 shape, and by its presenting but one articular face, which corresponds with one on the cuneiforme. It is always so prominent as to be felt without difficulty at the ulnar extre- mity of the wrist, and is very moveable. Of the Trapezium.—This bone is placed at the radial end of the second row ; its shape is exceedingly irregular, but it may be generally distinguished by be ng a bone of the third magnitude as regards the second row. It is better for the student to find out first the surface by which it articulates with the metacarpal bone of the thumb, which he can do in a short time by a comparison of the surfaces of the two bones. This being successful, will establish a clew to the other sur- faces, and to the relative position of the bone. The thumb surface is a concave cylindrical trochlea, placed on the radial side of the trapezium, and looking downwards and outwards. On the reversed or upper side is a small concavity, which receives the dorsal convexity of the scaphoid bone. Conti- nuous with this concavity is another on the ulnar side, which receives a corresponding convexity of the trapezoides. Be- tween this concavity and the one for the thumb is a small plane surface, by which the trapezium articulates partially with the metacarpal bone of the fore finger. The dorsal face is rough and unequal. The palmar face is unequally divided by a high ridge or process, at the ulnar side of whose root is a deep fossa for the tendon of the flexor carpi radialis. Of the Trapezoides___It is placed at the ulnar side of the last bone, and is the smallest in the second row. There is no liability of confounding it with any other bone of the carpus, as it is the least of any excepting the pisiforme. The greater difficulty is the adjustment of it in the separated bones, the following rule, however, will serve. It is sur- rounded by articular faces on its sides, but the dorsal surface presents a broad base, while the palmar extremity is reduced in size. Holding the bone with a reference to these, it will be observed that one side is very crooked and concave while 188 SKELETON. the reversed or opposite one is convex. The latter fits againsi the surface of the trapezium which has been indicated, while the former embraces the side of the os magnum just below its head. The metacarpal surface of the trapezium is long and elevated in its middle for being received into the rootol the metacarpal hone of the fore finger, while the upper sur- face presents a long concavity for receiving a part of the dorsal convexity of the scaphoides. Of the Magnum.—It is placed at the ulnar side of the trapezoides, and, from its being larger than any other hone in the carpus, will scarcelybe mistaken. Its ulnar side is flat and presents a plane surface for articulating with the unciforme. The radial side is uneven and rather indistinctly marked where it joins the trapezoides, but the latter surface will be found near the middle of this side just below the head. The upper surface of the magnum is formed into a spherical head, the radial side of which reposes in the concavity of the scaphoides, while the ulnar side is in the concavity of the lunare. Its metacarpal surface is oblong, convex, and wind- ing, by which it joins the metacarpal bone of the middle finger. On the radial side of this surface is a small one con- tinuous with it, whereby the magnum articulates partially with the metacarpal bone of the fore finger. The posterior or dorsal face is broad while the palmar is more narrow. Of the Unciforme.—It is placed at the ulnar side of the magnum, is nearly of the same size, but readily distinguisha- ble from it by its long crooked process as well as by its pe- culiar shape. Its radial side is plane where it joins the mag- num ; the reversed or ulnar side is brought to a thin edge. The metacarpal surface presents two distinct concavities, the one next the ulnar edge is for the metacarpal bone of the little finger, and the other for that of the ring finger. The upper surface is convex and winding, having its ulnar margin almost touching the surface for the metacarpal hone of the little finger. The most considerable portion of the upper surface reposes upon the cuneiforme, and the remain- THE HAND. 189 der upon a part of the concavity of the lunare. The poste- rior face is broad and rough, while the palmar is narrower. From the ulnar side of the latter projects the unciform pro- cess already alluded to. The two ranges of carpal bones thus fashioned, present. when articulated or united together, an oblong body, the greatest diameter of which is transverse. Its posterior face is semicylindrical and arched, while the anterior face is con- cave for the passing of the flexor tendons. Two protube- rances are found ofPeach extremity of the palmar surface. Those at the ulnar end are the pisiforme, and the unciform process of the unciforme ; those at the radial end are the pro- tuberance at the radial end of the scaphoides, and the sort of unciform process from the trapezium bounding the radial margin of its groove. These several prominences may. with a little attention, be readily distinguished beneath the skin. The superior face of the carpus, which articulates with the lower end of the radius and ulna, presents an oblong convex head formed by the scaphoides, the lunare, and very partially by the cuneiforme. The inferior face of the carpus presents a very diversified surface, subdivided into five distinct ones, each of which is fashioned according to the shape of the me- tacarpal bone with which it has to articulate. The central joint of the wrist, formed between the two rows of bones, is very deserving of attention. The first row is convex on its radial end, the convexity being formed on one half of the scaphoides : to the ulnar side of this there is a deep concavity formed by the other half of the scaphoides,— by the lunare and the cuneiforme. The upper surface of the second row fits very accurately upon the lower surface of the first: on its radial end is therefore a concavity formed by the trapezium, and trapezoides which receives the convexity of the scaphoid ; then a very large prominent head is formed by the magnum and unciforme. and received into the conca- vity of the first row. The magnum reposes upon the sca- phoides and part of the lunare, the unciforme upon the re- 190 SKELETON. mainder of the lunare and the whole of the cuneiforme. The carpal bones consist of cancellated matter enclosed by con- densed lamellated substance. Of the Metacarpus. The metacarpus is situated between the carpus and the phalanges of the fingers and thumb. It consists of five bones, one for the thumb and one for each finger. The latter are parallel or nearly so with each other, but the first diverges considerably, and is so placed as to ti%verse the others in front during its motions. These bones are rounded in their middles and enlarged at their extremities. That of the thumb is the shortest, the others decrease successively in length from the fore to the little finger. Of the First Metacarpal Bone or that of the Thumb.—It, besides being the shortest, is also the thickest of any. Its carpal surface is cylindrical and slightly concave from side to side, in order to present a fit surface to the trapezium. Its lower face is slightly convex, and elongated in front into a trochlea, on either side of which reposes a sesamoid bone. The posterior face of its body is flat and straight, the anterior is concave in its length and is divided into two surfaces by a middle ridge. A roughness exists on either side at its lower end, for the attachment of the lateral ligament. Of the Metacarpal Bone of the Fore Finger.—The greater length of this bone gives it a distinctive character. Its carpal face presents, in the middle, a deep concavity for receiving the trapezoides, at the radial side of which is a small plane face for articulating with the trapezium, and at the ulnar side an oblong surface, the upper margin of which joins the magnum and the remainder is in contact with the third metacarpal bone. The lower end presents a convex head extended in front, to concur in the flexion of the finger, on each side of which head is a concave rough surface for the lateral liga- ment. The posterior face of the bone presents a triangular THE HAND. 191 flat surface, the base of which is towards the finger or pha- langial end. The palmar face is concave longitudinally, and divided, by a middle ridge, into two surfaces, each of which is compressed by the inter-osseous muscles. A tubercle exists on the back of the bone just below its metacarpal end for the insertion of the tendon of the extensor carpi longior, and another in front for that of the flexor radialis. Of the Third Metacarpal Bone.—This is but slightly shorter than the last and is nearly of the same size, but its carpal extremity is very different. The latter is triangular and is bounded on its radial side by a sort of styloid process, with a tubercle on the posterior face of it, into which the ten- don of the extensor radialis brevior is inserted. It is placed upon the magnum to which it joins by a slightly concave, winding surface. It also presents, continuous with the same surface, an oblong face which joins the second metacarpal bone, and on the reversed side two round facets, which are contiguous to the fourth metacarpal bone. In regard to its lower or phalangial extremity and body, this bone resembles closely the one last described. Of the Fourth Metacarpal Bone.—This is much smaller and shorter than the third, and readily distinguishable by these circumstances. The carpal surface, by which it joins the unciforme, is triangular and slightly convex, a very small portion of its radial edge touches the magnum. Continnous with this edge are two small faces slightly convex, which join the contiguous faces of the third metacarpal bone. On the reversed side of the fourth metacarpal is an oblong face which joins the carpal end of the fifth metacarpal bone. In regard to its body and phalangial extremity this bone resem- bles the two preceding, and therefore does not require a par- ticular description. Of the Fifth Metacarpal Bone.—It is both smaller and shorter than the fourth. The carpal extremity presents a cylindroid and slightly convex face, for articulating with the 192 SKELETON. unciforme, at the radial margin of which is an oblong facet, for joining the fourth metacarpal : just below the ulnar mar- gin is a small tuberosity into which is inserted the tendon of the extensor ulnaris. The lower or phalangial extremity, like that of the others, presents a convex articular face extended in front for the flexion of the first phalanx. The body also corresponds with that of the others excepting that it is more flat in front. Of the Phalanges. Each finger has three bones in it called its phalanges; the bone adjoining the metacarpus is the first phalanx, the mid- dle bone is the second, and the other the third. The first phalanx is the largest. Its posterior face is semicylindrical, the anterior face is flattened and concave in its length. The two surfaces run into each other by forming a ridge on either side, from which arises the theca of the flexor tendons. The metacarpal extremity is enlarged and presents a superficial cavity, which receives the end of the metacarpal bone. On either side of this end of the bone is a small tuber for the lateral ligament. The lower extremity is also enlarged and flattened at its sides. Its articular face is extended in front, and presents two condyles or small heads for joining the second phalanx. The second phalanx is likewise second in size and length. It is semicylindrical on its posterior face, flattened on its anterior, which is somewhat concave in its length, and the two surfaces form a ridge on either side into which the ten- don of the flexor sublimis is inserted, and from which arises the theca of the flexor tendons. Its extremities are slightly enlarged : the articular face of the upper presents two su- perficial cavities for the condyles of the first phalanx; the articular face of the lower extremity presents a trochlea with a slight elevation at each side. ARTICULATIONS OF THE UPPER EXTREMITIES. ]<) The third phalanx is the smallest of the three, and is very different from the others. Its superior extremity being en- larged, presents an articular face having two superficial cavities, which adjust themselves to the corresponding face of the last described bone. The inferior extremity is semi- circular, thin, and flattened, its margin being very rough, and somewhat expanded. The posterior face of the body is convex, and the anterior flat. The phalanges of the middle finger are larger and longer than the others. The phalanges of the fore finger are next in size but not in length, as the ring finger is rather longer than it. The phalanges of the ring finger are next in size, and those of the little finger the smallest and shortest of any. The thumb having but two phalanges, the first corresponds sufficiently in its general form with the first one of the fingers; it may be distinguished, however, by its shortness and addi- tional size. The second phalanx of the thumb, corresponding with the third of the fingers, is only to be distinguished by its additional bulk and length. All the metacarpal and phalangial bones have a condensed lamellated structure externally, and a cancellated one inter- nally ; and, like other long bones, are more compact in their bodies than at their extremities. There are two small hemispherical bones called Sesamoid, placed upon the trochlea, at the lower extremity of the meta- carpal bone of the thumb. They answer the purposes of pa- tellae, and facilitate the action of the short flexor muscle. The metacarpal bones of some of the fingers are, in robust individuals, occasionally furnished in the same way. SECT. V.—OF THE ARTICULATIONS OF THE UPPER EXTREMITIES. Of the Articulations of the Shoulder. These articulations consist in the junction of the clavicle to •he upper part of the sternum and to the first rib; of that vol. i.—b b 194 SKELETON. of the clavicle to the scapula; and of that of the os humeri to the scapula. 1. Of the Sterna-Clavicular Articulation. The uneven triangular face of the clavicle internally, and the concavity of the sternum at its upper corner, form the surfaces which enter into this articulation. The former is much more extensive than the latter, projects on every side beyond its margins, and is very prominent in cases of ex- treme emaciation. The two surfaces are covered by carti- lage, of which that on the clavicle is the thickest, and serves to fill up its inequalities ; while the one on the sternum is thin and smooth. The joint is invested by a thick fibrous capsule, the anterior portion of which presents a strong fasciculus of parallel fibres, somewhat separated by small interstices. This por- tion, called by some the radiated ligament, arises from the anterior extremity of the clavicle, and going downwards and inwards, is inserted into the margin of the articular cavity of the sternum. It is placed just behind the origin of the sterno-cleido mastoid muscle. The capsular ligament is also strengthened on its posterior surface by additional fibres, not so distinct as the preceding, but obtaining the name of the posterior ligament. Of the Inter Clavicular Ligament.—Closely connected with the capsule of the joint, this ligament is placed on the superior end of the sternum, and extends from the internal end of one clavicle to that of the other. It is flat before and behind, thin and narrow, is blended with the contiguous liga- mentous structrue of the sternum, and might with propriety have its distinctive character sunk, so as to be considered only an appendage to the capsular ligaments, or a process sent between them. In front it corresponds with the integu- ments, and behind with the sterno-hyoid muscles. Of the Inter-Articular Cartilage.—.When the capsule of ARTICULATIONS OF THE UPPER EXTREMITIES. \QQ the joint is cut open, this is brought into view. It separates the bones completely from each other by its extent, and sup- plies by its shape the want of correspondence in their articu- lar faces. It is thicker above than below ; its centre is thin and sometimes perforated. Its margins adhere closely to the capsular ligament; it is also fixed by adhesion to the upper posterior margin of the surface of the clavicle, and be- low to the union of the sternum with the first rib, in conse- quence of which it has but little motion, and in luxations must be lacerated. Its structure is fibro-cartilaginous. Of the Synovial Membranes.—There are two of these, one on each side of the inter-articular cartilage, in consequence of which a double cavity exists in this articulation, except- ing the cases where the cartilage is perforated. These mem- branes contain but little synovia; they adhere closely to the adjoining surfaces, and cannot be made very distinct, except in points where there are small interstices in the capsule, when, by pressing the bones strongly together, they protrude into little vesicles. Of the Costo-Clavicular Articulation.—It consists in a short fasciculus of ligamentous fibres, frequently called the rhomboid ligament which, arising from the upper surface of the cartilage of the first rib, ascends obliquely outwards, and is implanted into the roughness on the inferior face of the clavicle, near its sternal end. Its fibres are parallel, all oblique, and longer at its external than at its internal mar- gin. It corresponds in front to the origin of the subclavius muscle, and behind to the subclavian vein. It has for its object the strengthening of the junction of the clavicle with the sternum. 2. Of the Scapulo-Clavicular Articulations. These are formed at three points : the first by a junction between the acromion scapulae and the external end of the clavicle; and the two last by ligaments sent from the cora- coid process to the under surface of the clavicle. 196 SKELETON. The Acromio Clavicular Articulation presents, on each bone, a small oblong face, covered with cartilage. The fibrous capsule which invests it is very strong and thick, so as to give the appearance of a much greater extent to the articular faces of the bones than really exists. This capsule is strengthened by additional fibres on its upper surface, passing from one bone to the other, and sometimes called the superior ligament; they are parallel to each other, and somewhat blended with the tendinous fihres of the deltoid and trapezius muscles. The capsule is also strengthened, on its lower face, by addi- tional fibres, constituting the inferior ligament; they are not so abundant as the superior, and pass from the margin of one bone to that of the other after the same manner. A synovial membrane is reflected over these articular surfaces, and con- tains but a very small quantity of fluid. In some instances, an inter-articular cartilage is found in this joint, as in the sterno-clavicular; in such case there is a double synovial membrane. Of the Coraco-Clavicular Ligament.—This ligament is double, one part being called the Conoid, and the other the Trapezoid. It arises from the roughness at the root of the coracoid process, and is attached to the under surface of the clavicle. The conoidal portion, having its base upwards, is inserted into the tubercle, near the external end of the cla- vicle. Its fibres are compact, strong, and diverging. The trapezoid is placed at the acromial side of the other. It is quadrilateral, longer, broader, and thinner than the other, having its fibres separated by small interstices ; and arising also from the root of the coracoid process, it is inserted ijito an oblique line leading from the tubercle of the clavicle to its acromial end. The union of these two portions behind forms a projecting angle; in front there is a depression between them filled with fat and cellular substance, also a bursa mucosa. These ligaments are bounded in front by the sub- clavius, and behind by the trapezius muscle. The Ligamentum Bicorne is placed in front of the subcla- ARTICULATIONS OF THE UPPER EXTREMITIES. J 97 vius muscle. It arises from the root of the coracoid process, at the sternal side of the conoid ligament; and proceeding, with but little elevation, inwards and upwards, increases in breadth and bifurcates. The superior horn is inserted into the under margin of the clavicle, near the rhomboid or costo- clavicular ligament; but the lower one goes to the end of the first rib, under the tendon of the subclavius muscle. This ligament is a sort of fascia placed over the subclavius muscle, to bind and strengthen it. Some of the fibres of the superior horn sometimes proceed further, and leaving the clavicle, go with the rhomboid ligament into the cartilage of the first rib.* The Coracoid Ligament subtends the notch on the supe- rior costa of the scapula, and converts it into a foramen. It runs from the posterior margin of the notch to the base of the coracoid process, and has some of its fibres blending with the conoid ligament. It consists of a small fasciculus of fibres, and is of very little consequence, excepting its relation to the superior scapular vessels and nerves. The Coraco-Acromialis, or the Triangular Ligament of the Scapula, as its name implies, extends from the coracoid to the acromion process, above the shoulder joint. It arises from nearly the whole superior margin of the coracoid pro- cess, in two divisions, separated partially by cellular tissue, Its fibres converge in their progress, by which it becomes thicker, and is inserted into the point of the acromion pro- cess, just beneatli its junction with the clavicle. This liga- ment is covered by the deltoid and the clavicle, and has the supra-spinatus beneath it. Its anterior margin is continuous with a condensed cellular membrane beneath the deltoid. On the Motions of the Shoulder. The clavicle performs a very important office in the actions of the shoulder, by preserving it in a fit attitude for the * Caldaiu, Plate XLT, 198 SKELETON. motions of the upper extremity. The simple movements of the clavicle, of which the sterno-clavicular articulation is the centre, are those of elevation, depression, advancing and retreating, and a rapid succession of these produces circum- duction. The weight of the shoulder is also sustained by the clavicle, by the latter being fastened at the extremity next to the sternum, and having in the cartilage of the first rib a fulcrum, intermediate to this attachment and to the weight at its other end. This is proved conclusively by its fracture, for in that case the shoulder invariably falls down, from the lever being broken which kept it up. The clavicle, also, by keeping the glenoid cavity at a dis- tance from the side of the thorax and directed outwards, gives great facility and latitude to certain motions in the human subject; and which are performed with difficulty, and very im- perfectly, in animals not having a clavicle. A principal one of these motions is circumduction, manifested by the elbow being turned inwards or outwards, and in most persons ex- tends to three-fourths or even an entire circle. This motion concurs in the action which brings the hand to the mouth, in consequence of which such an action is performed with diffi- culty when the clavicle is broken. After an accident of the kind, the head instead of remaining stationary as usual, is advanced towards the hand, without which the act cannot be accom- plished. A certain length in the clavicle seems indispensable to the vigorous, and perfect action of the shoulder in particular movements ; if the clavicle be disproportionately long, as in females, these movements are executed with inevitable awk- wardness and imbecility, as for example in throwing a stone. The Scapula presents a moveable basis, on which the mo- tions of the arm are accomplished. Its primary motions are such as have been assigned to the clavicle, in consequence of the connexion between these bones, besides which, in all the extreme motions of the humerus, backwards or forwards, the scapula is caused to perform a partial rotation, the axis of which is indicated by a line drawn from the end of the acro- mion to the inferior angle. When the arm is brought very ARTICULATIONS OF THE UPPER EXTREMITIES. J 99 far forwards, the inferior angle of the scapula is carried outwards and somewhat elevated, while the superior angle is directed towards the spine and somewhat depressed. But, when the arm is carried very far backwards, the inferior angle is directed towTards the spine, and the superior angle looks forwards and upwards. The clavicle in these cases moves inconsiderably, as the scapula enjoys a pendulous motion, and its point of suspension is the outer end of the clavicle; at which place the oblong articular surfaces slide laterally upon each other and decussate. The extreme de- grees of these motions tend to dislocate this articulation, but the accident is prevented by the strong coraco-clavicular ligament, which, by its peculiar position and conformation, resists firmly at a certain point. In the abduction and ad duction of the arm the scapula is motionless. Of the Scapulo-Humeral Articulation. The glenoid cavity of the scapula, and the head of the os humeri found this joint. As usual, each articular surface is covered with cartilage, of which, that on the os humeri is thicker in the middle than near its circumference, while the reverse occurs on the scapula. From the shallowness of the glenoid cavity and the much greater size of the head of the os humeri, but very few points of their opposed surfaces can come into contact at the same moment, though they may all do so in succession, hence a considerable portion of the head of the humerus is always against the capsule of the joint. The remaining parts of this articulation are the capsular ligament, the synovial membrane, and the glenoid ligament. The capsular ligament invests completely this joint, though it is thinner in some places than at others. It arises from the margin of the glenoid cavity, and is inserted into the neck of the os humeri, including a larger space of the neck below, than it does above. The tendons of the muscles which arise from the external and internal surface of the scapula, to be inserted into the tuberosities of the os humeri, as they 200 SKULL TON. approach their points of insertion adhere very closely to the capsular ligament, and are, indeed, more or less blended with it. Bichat considers, that the tendon of the sub-scapu- laris muscle supplies its place entirely at its lower part. This ligament is formed from fibres, which are very much blended with one another, and have a greater degree of thick- ness above than below, or indeed at any other point. The former is due to a thick fasciculus, called by some Liga- mentum Adscititium, which takes its origin from the poste- rior and external margin of the coracoid process, and pro- ceeding beneath the triangular ligament to the upper part of the os humeri, joins the capsular ligament and adheres very firmly to it. This ligament keeps the head of the os humeri on its proper level in regard to the glenoid cavity ; hut the moment it is cut, the length of the capsular ligament permits the head to fall about an inch below the cavity, and indeed to suffer a partial dislocation. The strength of the joint, however, depends essentially upon the muscles which sur- round it, as the deltoid, supra-spinatus, infra-spinatus, teres minor, sub-scapularis, long head of triceps, and some others. which are further removed from it. The synovial membrane is a perfect sac, which covers the glenoid cavity, the internal face of the capsular ligament, and the neck and head of the os humeri. On the lower part of the neck it is reflected over some small fatty masses, com- monly called glands. Just beneath the root of the coracoid process, from there being a deficiency of the capsular liga- ment, the synovial membrane covers the articular side of the tendon of the sub-scapularis, and is reflected for ten or twelve lines, between it and the scapula, forming a sort of pouch resembling a bursa mucosa. The tendon of the biceps muscle runs through this articu- lation from the superior end of the glenoid cavity. The ca- vity itself is deepened by a fibrous margin all around called the glenoid ligament, a considerable part of whose fibres may be traced from the tendon of the biceps by its bifurcating. ARTICULATIONS OF THE UPPER EXTREMITIES. gfj| The tendon is bound down in the bicipital groove by fibres passing from one to the other of the bony margins, and which may be considered a continuation of the capsular ligament. As the tendon is about emerging from the groove at the lower margin of the tuberosities, the synovial membrane which lines the groove thus far, is reflected from it, to the surface of the tendon, and continues to cover and enclose it up to the origin at the glenoid cavity. It is thus evident that though the tendon passes through the joint, the cavity of the syno- vial membrane is kept entire. Of the Elbow Joint. This articulation is founded by the lower end of the os hu- meri and the upper of the ulna and of the radius. The ar- ticular faces which were described in the account of these bones are covered, as usual, with cartilage, the particular arrangement of which will be presently pointed out. A strong capsular ligament, an annular or coronary ligament, and a synovial membrane, hold these several bones together. The Capsular Ligament invests completely the articular extremities of these bones, and conceals them from view. It is attached to the sides of the humerus at the lower part of its condyles near the articular surface, but in front it arises some distance from the articular face at the upper margins of the little cavities, for the head of the radius and the coro- noid process of the ulna; behind it arises in like manner from the upper margin of the cavity for receiving the olecranon process, so that the depressions, both before and behind, are included within the circumference of the articulation. The lower part of the capsular ligament is inserted into the mar- gin of the articular surface of the ulna all around, including, also the whole of the head of the radius, and the upper part of its neck. This capsule is strengthened very much at particular points, and as the joint is hinge-like, the strengthening is more abun dant at its sides, constituting lateral ligaments. vol. i.—c c 202 SKELETON. The External Lateral or the Brachio Radial Ligament is connected above to the lower part of the external condyle, and is fixed belowT into the annular ligament w hich surrounds the neck of the radius. It is xery much confounded with the tendinous mass common to the muscles at this part of the arm, more particularly that of the supinator radii brevis. It is a long round fasciculus of parallel and condensed fibres, spreading somewhat below into the orbicular ligament. The Internal Lateral or the Brachio Ulnar Ligament arises from the lower part of the internal condyle, and spreading out so as to assume a triangular shape divides into two portions, one of which is inserted into the internal margin of the co- ronoid process of the ulna, and the other into the internal margin of the olecranon process. It also is much blended with the tendons of the muscles which lie over it. Interme- diately to the lateral ligaments, both before and behind, the fibrous structure of the capsular ligament is very distinct, but thin, in order to accommodate the motions of the joint: some of the fibres are insulated, and have interstices between them filled with fat. Some of these fibres are oblique and others straight; they are called generally accessary ligaments. The Coronary Ligament of the radius is brought more distinctly into view by cutting open the joint. It is then seen to arise from the anterior margin of the lesser sigmoid cavity of the ulna, and surrounding two-thirds of the neck of the radius to be inserted into the posterior margin of the same- cavity. It is a strong, flat, narrow, fasciculus, the fibres of which go in a circular direction. Its superior margin is blended with the external lateral ligament; its inferior mar- gin is loose, being connected with the lower part of the neck of the radius only by a reflection of the synovial membrane, with the exception that a few fibres pass from it behind, to the contiguous part of the ulna. Its density is very consi- derable, sometimes almost cartilaginous. The Synovial Membrane lines the whole internal face of the capsular ligament, from which it is separated behind by ARTICULATIONS OF THE UPPER EXTREMITIES. £03 a large mass of fat in the olecranon depression of the os humeri, and in front by another mass in the coronoid depres- sion. A small circular ridge of fat also projects into the joint around the head of the radius, and there is another at the internal margin of the olecranon. The object of these masses seems to be to fill up the partial vacancies which ex- ist between the articular faces of the bones, and they are all so managed by their attachment to the capsular ligament as to preserve them from being pinched. The synovial mem- brane is also reflected from the capsular ligament to the arti- cular faces of the bones, so as to line the several depressions on the os humeri, and to include the neck of the radius. The head of the radius is completely invested with carti- lage. The greater sigmoid cavity of the ulna has the carti- lage separated transversely into two portions by a small mass of fat traversing its bottom. The cartilage elsewhere is uniformly spread over the articular surfaces of the bones. Of the Interosseal Ligament.—It fills up the space be- tween the two bones of the fore-arm almost entirely, by com- mencing just below the tubercle of the radius and ending near the wrist. It consists in oblique and parallel fibres, which pass from the ulnar edge of the radius downwards to the radial edge of the ulna. It is thin, but extremely strong, being covered in front by the flexor muscles, and behind by the extensors, and as Mr. Boyer observes, seems to be in- tended rather to afford origin to muscles than to unite the bones. Its superior part is thinner above, and a large open- ing exists there for the passing of the interosseal vessels to the back of the fore-arm. Its inferior part is thicker, where openings also exist, but small, for the passing of vessels. There are some other smaller perforations in this ligament, but of less note than the preceding, also for vessels. On its posterior face there are one or two bands, the fibres of which decussate the other fibres. Beside the interosseal ligament there is one called round, situated obliquely between the two bones at the upper part of the interval which separates them. It arises from the base 204 SKELETON. of the coronoid process just below the insertion of the bra- chialis internus, and descending obliquely outwards, is in- serted into the radius just below its tuberosity. Its object is to bind the bones together, at a point which is weakened by the deficiency of the interosspalligament. This deficiency is, in fact, much larger than the simple passing of the ves- sels requires, for it is also large enough to allow the tubercle of the radius to rotate freely, a motion which would have been checked by the presence of the ligament. Of the Articulations of the Wrist. Several articular cavities present themselves at this point. One is between the lower part of the ulna and the radius, another between the carpal bones and those of the fore-arm, and a third between the two rows of carpal bones. One ge- neral capsule invests these parts. 1. The Lower Radio-Ulnar Articulation—is surrounded by a section of the fibres belonging to the general capsular ligament, their attachment however is so loose, that they allow the bones to rotate freely upon each other, besides which they are not so abundant as in other places. When this joint is cut open it will be seen that the head of the ulna is covered with cartilage, and that the cartilage which covers the carpal articular face of the radius, projects between the ulna and the os cuneiforme, lining also the sigmoid cavity of the radius, so that a cavity for receiving the convex head of the ulna is formed by the two latter sections of the radial cartilage. The margins of this projecting point of the radial cartilage are fibrous, which has induced the French anato- mists to speak of it under the name of triangular ligament. It is said to be occasionally detached from the radius, but I have not seen it in that state; its centre not unfrequently is perforated, so that a communication exists betw een this joint and the next of the wrist. Its margins adhere very closely to the capsular ligament, and its point is fixed into the de- pression which separates the styloid process of the ulna from ARTICULATIONS OF THE UPPER EXTREMITIES. 205 its head. The synovial membrane which lines this cavity is unusually loose, both before and behind, in consequence of the great motion of the bones : it is also very loose above. This joint is some times called the Sacciform, from its looseness. 2. Of the Radio-Carpal Articulation.—The radius above, and the scaphoides, lunare, and cuneiforme below, form the basis of this articulation. An oblong, elliptical cavity, the ulnar extremity of which is made by the projection of the cartilage on the articular face of the radius, receives the con- vexity of the bones of the wrist. The scaphoides and the lunare come in contact with the radius, while the cuneiforme rests against the projecting cartilage. There is a slight ele- vation of the radial cartilage opposite to the interstice be- tween the two first bones. The oblong elliptical cavity is filled by a corresponding head, on the part of the bones of the carpus just enumerated. Each of the latter hones in a fresh state, is covered by its appropriate cartilage. The car- tilages are connected, or rather continued into one another, by a narrow ligamento-cartilaginous substance placed at the margin of the interstice between these bones. This substance separates the cavity of the radio-carpal articulation from that of the proper carpal articulation. The Capsular Ligament arises, before and behind, round the margin of the articular face of the bones of the fore-arm, from the styloid process on one side to that on the other, ad- hering very closely to the margins of the triangular carti- lage between the ulna and the cuneiforme. It is inserted below, into the circumference of the head formed by the sca- phoides, lunare, and cuneiform, though many of its fibres may be traced to the bones of the second row. It is a loose and thin membrane, the fibrous fasciculi of which leave in- terstices at several points between them, through which the synovial membrane may be seen. The capsular ligament is strengthened at particular places, by additional fasciculi of fibres having appropriate names. For example, the 206 SKELETON internal lateral ligament arises from the styloid process of the ulna, and is inserted into the cuneiforme, some of its fibres being extended to the anterior annular ligament, and to the pisiforme. The external lateral ligament arises from the styloid process of the radius, and is inserted into the ra- dial end of the scaphoides, some of its fibres being continued on to the trapezium, and to the anterior annular ligament. The anterior ligament arises from the vicinity of the styloid process of the radius, and passing obliquely downwards and inwards, is inserted into the anterior face of the scaphoides, lunare, and cuneiforme. Its fibres are not very evident or well marked. The posterior ligament is n.)t so broad as the last, and is more distinct. It also arises from the radius, by and near its styloid process, and descending obliquely in- wards, is inserted into the lunare and cuneiforme. The two last ligaments have no connexion with the ulna, the rotation of that bone is therefore unimpeded by them. The Synovial Membrane of the radio-carpal articulation is displayed on the articular faces of the bones and the inter- mediate cartilage, and lines the internal face of the capsular ligament. When the joint is pressed upon, this membrane is protruded, in the form of little vesicles, in the interstices between the fasciculi of the capsular ligament. A fold of it containing a small quantity of adipose matter is observed on the back of the cavity of the joint, passing from the junction of the scaphoides and lunare to the corresponding point of the radius ; it is the ligamentum mucosum of some writers. 3. Of the Articulation between the two rows of the Carpal Bones—The scaphoides, lunare, and cuneiforme of the first row, and all the bones of the second row, lay the foundation of this joint, the surfaces of which have been described already. These surfaces are covered with cartilage, each bone having its appropriate cartilage, which is continued on its side where the bone touches the adjacent one. The joint is furnished vith a capsular ligament and a synovial membrane. ARTICULATIONS OF THE UPPER EXTREMITIES. gfj7 The Capsular Ligament surrounds the articulation, passing on exery side from the upper to the lower row, and adhering strongly to the bones. It is in a great degree a continuation of the capsule of the radio-carpal joint, and has, at the same points, an increase of thickness, called after the same names. The internal lateral ligament is attached by one end to the cuneiforme, and by the other to the side of the unciforme. The external lateral ligament arises from the extremity of the scaphoides, and is inserted into the side of the trapezium. The posterior and anterior ligaments have the course of their fibres more distinctly seen on the side of the synovial mem- brane. The first consists in many fibres arising from the bones of the first row and going to the second row ; its fibres are shorter and more compact. The anterior arises and is inserted after the same way, some of them terminating in the anterior ligaments of the hand. The Synovial Membrane is not only displayed on the op- posite surfaces of the two carpal rows, but also is reflected upon the lateral faces of the bones belonging to each row. It therefore sends processes, two of which are found above, one between the scaphoides and lunare, and the other between the lunare and cuneiforme. These processes are arrested at their upper extremities by the fibro-cartilaginous matter be tween these bones, which was spoken of in the radio-carpal articulation. It also sends three processes downwards, one between the trapezium and the trapezoides, another between the latter and the magnum, and the third between the mag- num and the unciforme. These latter processes communicate with or are continuous with the synovial membrane, between the carpal and the metacarpal bones of the fingers.* The connexions and reflections of this membrane arc of the great- est importance, as they form a communication from the top of the wrist to the base of the metacarpal bones; not only covering the articular surfaces, but being prolonged in some instances beyond them, as on the back of the neck of the os magnum where it answers as a periosteum. * Bichat, Amit. Dcscr 208 SKELETON In addition to the articulation just described, between the two rows of carpal bones, the individual bones of each row have particular fastenings of ligamentous fibres which run transversely from the margin of one bone to the margin ol the next. These fibres, from their position, are called dorsal and palmar ligaments. The upper row has one dorsal liga- ment between the scaphoid and lunar, and another between the latter and the cuneiform—it has in the same way two palmar ligaments on its front surface. The lower row has, after the same plan, three dorsal and three palmar ligaments between its bones. These several ligaments are best seen on the side of the synovial membrane, as externally their fibres are very much mixed with those of the capsular liga- ment. It is obvious that they are highly useful in prevent- ing the bones from sliding laterally, on each other, except to a small extent. The Pisiform Bone has an articulation with the cuneiform completely distinct from any other. The articular faces of this joint are covered with cartilage, and invested by a sy- novial membrane and a capsular ligament which allow, from their looseness, considerable motion. The capsule, though generally thin, is strengthened by accessory fibres, which arc well marked below. These fibres arising from the infe- rior extremity of the pisiform, some of them are attached to the extremity of the unciform process, and others to the base of the fifth metacarpal bone. The insertion of the tendon of the flexor carpi ulnaris answers as a ligament to this bone above. It has but'little motion from ahove downwards and a good deal laterally. Of the Carpo-Metacarpal Articulations. The bony articular surfaces, here, as well as all the others of the band, have been sufficiently described, and are in the recent state covered with cartilage. It will therefore be un- necessary to renew the observations on these subjects. ARTICULATIONS OF THE UPPER EXTREMITIES. £09 The first of these articulations, or that of the metacarpal bone of the thumb, with the trapezium, is much more move- able than any of the others, and presents some peculiarities. It is entirely distinct, slightly removed from the next, and is surrounded by a capsule, which is attached by its ends to the articular margins of the bones. This capsule is strength- ened by additional fibres all around, which are particularly distinct and abundant, posteriorly and externally. The syno- vial membrane is displayed, as usual, on the internal face of the capsule and over the articular faces. The other four metacarpal bones are articulated as fol- lows. The second one is joined to the trapezoides, trape- zium, and magnum—the third unites to the magnum alone— the fourth to the unciforme, with a small portion of the mag- num—and the fifth to the unciforme. The ligaments are placed before and behind, and may be termed dorsal and palmar. The dorsal ligaments descend from the carpal to the me- tacarpal bones. The second metacarpal bone receives two ligaments, one from the trapezium, and another from the trapezoides—the third receives one from the magnum—the fourth receives two, one from the magnum, and the other from the unciforme—the fifth receives one from the unci- forme. Transverse fibres to the bones pass between these dorsal ligaments. The palmar ligaments are arranged on a plan correspond- ing with that of the dorsal, but from the length of their superficial fibres are not so distinct from each other. Trans- verse fibres pass between them also, forming a sort of inter- osseous ligaments, which keep the metacarpal bones together. The articulations thus formed and held together, are co- vered by two synovial membranes, being processes from that between the two rows of carpal bones. One of these pro- cesses is sent down between the trapezoides and the magnum, and there displays itself over the inferior surface of these bones, and the head «»f the metacarpal bone of the fore and of the middle finger. The second process is sent, down between vol. i.—w d 210 SKELETON the magnum and unciforme, and is there reflected over the two last carpo-metacarpal articulations. These two pro- cesses have a septum between them, at the ulnar side of the base of the third metacarpal bone, and do not communicate, with each other, except through the proper carpal articula- tion. The specification of this arrangement is overlooked by anatomists generally. The Inferior Palmar Ligaments are between the lower ends of the metacarpal bones of the fingers, and consist in a transverse fasciculus, placed between the flexor tendons and the interosseous muscles, and on a level with the anterior part of the first joint of the fingers. Its more superficial fibres may be traced across the bones, and are somewhat blended with the capsular ligaments; the more deep seated are short, and pass from one bone to the other. Of the Metacarpo-Phalangial Articulations. These are formed by the lower ends of the metacarpal bones, and the upper ends of the first phalanges. Each one presents an anterior ligament, two lateral ones, and a syno- vial membrane. The Anterior Ligament* is a flat, fibrous semicircle, on the front of the articulation, of considerable thickness. 11 goes transversely, and has its two extremities attached to the ridge on either side of the articular margin of the meta- carpal bone. Its inferior margin descends a little, and comes in contact with the synovial membrane. In front, many of its fibres are obtained from the ligamento-cartilaginous sheaths of the flexor tendons, so that it may be considered as made by two planes—the palmar one facing towards the tendons and forming the trochlea, hi which they play, and the other being next to the joint, and continued to the lateral ligaments. The thickness of the anterior ligament, besides * Bichat, loc. cit. ARTICULATIONS OF THE UPPER EXTREMITIES. 211 communicating great strength to the joint, is useful in re- moving the tendons from the line of motion of the phalanges, ami thereby giving increased power and delicacy of motion to the muscles. Bichat considers himself to have first indi- cated particularly this structure, which he thought was in- tended to protect the articulation from the impression of the tendon; he ought to have added, in the firm grasping of bodies, and to make the movements of the joint more delicate. On either side of this ligament, belonging to the thumb, and in its thickness, is developed a sesamoid bone. The Lateral Ligaments are two in number, one on either side. They arise from the sides of the metacarpal bone be- hind the former and in connexion with it, and descending obliquely forwards, are fixed into the sides of the upper end of the first phalanx. They are round, distinct, and strong, and are formed from numerous parallel fibres. The Synovial Membrane lines this articulation, being re- flected over its lateral and anterior ligaments, and on the articular faces of the bones. It is reflected on the metacar- pal bone, some little distance from the margin of its cartilage in front, whereby the cavity is enlarged, and the flexion of the fingers is favoured. It is in contact behind with the ten- don of the extensor muscle, which there supplies the place of ligament. Of the Phalangial Articulations. There are two of these to each finger, and one only to the thumb. They are provided with an anterior ligament, a lateral ligament on each side, and a synovial membrane. The Anterior Ligament corresponds so exactly with what has been said in the preceding article on the same structure, that, with the exception of its being smaller, the description already given will suffice. It seems to answer, in every re- spect, the same objects. f~ i & SKELETON The Lateral Ligaments, also, arising from the sides of the phalanx above, run downwards and somewhat forwards, to be inserted into the upper part of the sides of the phalanx below. The Synovial Membrane has reflexions corresponding with those of the preceding articulations, with the addition that it covers more of the anterior inferior face of the second and third phalanges. Thus, by cutting through the anterior ligament longitudinally and turning it aside, it will be seen that the cavity of the second and third joints of the finger is, by this reflection of the synovial membrane, extended upwards between the phalanx and the flexor tendons nearly one-third of the whole length of the phalanx,* a circumstance worth attending to in the accidents of the part. SECT. VI.--OF THE DEVELOPMENT OF THE UPPER EXTREMITIES. At birth the upper extremities are larger in proportion to the lower than they are at any subsequent period of life, owing perhaps to the umbilical arteries, which carried off to the placenta of the mother the greater part of the blood which afterwards goes to the lower extremities. The nearer a foetus may be to the embryo state, the more marked is this relative size of the extremities, which becomes gradually less obvious till the age of puberty, when it almost entirely disappears. At birth the ends of the Clavicle are, in consequence of their advanced ossification, much less cartilaginous than those of the other cylindrical bones. Its shape, also, ap- proaches nearly to that of the adult state. The Scapula is also in an advanced stage of ossification, and large. The glenoid cavity, though still cartilaginous, is well sustained by a bony basement coming from the cen- tral point of ossification of the scapula, and is much further * Bichat, loc. cit. DEVELOPMENT OF THE UPPER EXTREMITIES. 213 ossified than the acetabulum. The acromion, the coracoid process, and the angles, are still cartilaginous. The Os Humeri is cartilaginous at both extremities, which are also larger proportionally in consequence of this state. Its inferior extremity is remarkable for the size of that por- tion of it which articulates with the radius. In the fore-arm the extremities of its bones are cartilaginous. The Ulna has the olecranon large, while its coronoid process is comparatively small; the greater sigmoid cavity is conse- quently not so concave as in the adult. The position of the radius, at its upper end, is somewhat peculiar, for it is much more anterior than in the adult, a circumstance depending upon the greater size of the little head of the humerus upon which it rests. This arrangement renders pronation more extended in the foetus, as the radius always crosses the ulna with additional facility, by being placed more anterior to it. This fact is strongly exemplified in the bones of an upper extremity of animals. Bichat observes, that this greater extent of pronation exposes the annular ligament to being stretched considerably behind, and consequently the radius to luxations at its head, an accident by no means unfrequent among children. Dr. Physick says, that he has often seen it in consequence of nurses incautiously seizing them by the fore-arm to help them over gutters, or to render them other assistance. It happens while the arm is in a state of pronation; for the weight of the body, by hanging from it, increases the position, distends the ligaments, and produces luxation. As the bones of the fore-arm in the foetus are nearly straight, the interosseal space decreases gradually from above downwards. The Carpus is entirely cartilaginous at birth, and consists in the same number of pieces that it does in the adult. Its articular cavities are well formed. Its size is proportion- ate to what it is in the adult; in this respect it differs from the cartilaginous extremities of the round bones, which are always larger from being in this state. The carpus there- fore appears small in the foetus. The Metacarpus is cartilaginous at its extremities, but ossified in the middle. The phalanges are in the same state. JU SKELETON. SECT. VII.—OF THE MECIHXI5M OF THE UPPEH EXTREMITIES. The scapula and clavicle arc for the superior extremity what the os innominatum is for the inferior, in consequence of which, same anatomists consider them, with some pro- priety, as a part of the trunk of the body. Though the con- venience of anatomical description generally requires them to be associated with the upper extremity, I shall depart from the rule on the present occasion, and view them only as the basis of the attachments and motions of the os humeri, and of the remaining parts of the superior extremity. The upper extremities, considering them as commencing with the ossa humeri, differ materially in their position from the lower. They are placed much further behind ; of which one may be satisfied fully by drawing a line from the middle of the glenoid cavity, to the middle of the acetabulum of the same side, the body being perfectly erect at the time; the line will be found oblique. The advantage of this ar- rangement is to give greater latitude of motion to the upper extremity than if it had been placed more in front Another important benefit is, that by the bulk of the shoulder being placed behind, the centre of gravity in the erect position is more easily preserved ; a different position of it, by throwing its weight forwards, would have had a continual tendency to produce falls, and would have effected somewhat in man the same inconvenience which is felt by the quadruped in the erect position. Another point, also of some interest, in the position of the upper extremities is, the distance to which they are separated from each other, by the lateral projection of the scapulae, and consequently of the glenoid cavities. A distance owing to the length of the clavicles, and which con- siderably exceeds the distance between the heads of the ossa femoris. When the whole length of the superior is compared with that of the inferior extremities, the difference is not so great as one may suppose. The former is ascertained by a line MOTIONS OF THE SHOULDER JOINT. 21$ drawn from the head of the os humeri to the end of the mid- dle finger: as the hand is parallel with the bones of the fore- arm, its length is also included, which amounts to a consi- derable portion of the whole. On the contrary, from the foot being articulated at right angles with the leg, only its thickness contributes to the length of the lower extre- mity. As far, however, as individual bones are concerned, those of the upper extremity, with the exception of its pha- langes are uniformly shorter than the corresponding bones of the lower extremity. The os humeri is much shorter than the os femoris—the bones of the fore-arm than the bones of the leg—the carpal and metacarpal bones than the tarsal and metatarsal. The bones of the upper extremity are much less robust than those of the lower, a very certain indication of the dif- ference of the uses for which they were intended. Their ar- ticular surfaces are arranged for great variety and extent of motion, in the seizing and handling of bodies, whereas in the lower extremity, they are fashioned so as to suit the compa- ratively limited number of motions requisite to progression, and to sustaining the body firmly in the upright position. The carpus and metacarpus are much smaller than the tarsus and the metatarsus, because the latter are intended to support a great weight. On the contrary the phalanges of the fingers are much better developed than the phalanges of the toes, because the latter are not destined to hold bodies and to ex- amine them, and may be dispensed with both in standing and in progression. The motions of the upper extremity are immensely varied, and by a short attention to them some useful hints may be obtained in regard to dislocations. iECT. VIII.—OF THE MOTTO'S OF THE SHOULDER JOINT. The os humeri is susceptible of elevation, depression, ad- vanciug, retreating, circumduction, and rotation. In elevation, the head of the os humeri slides downwards 21b" SKELETON in the glenoid cavity, and distends the lower part of the cap- sular ligament. In this motion the scapula is apt to follow it, in which case there will be a less degree of distention on the capsular ligament. If the os humeri be carried forwards, its elevation is performed with much more ease, from the readiness with which the scapula follows it, hut if it be carried backwards, this facility is much diminished. It is in the latter position, therefore, that dislocations downwards are most disposed to occur when violence is offered to the joint. If in every case the scapula could follow the motions of the os humeri, so as to present fairly its glenoid cavity, luxa- tions would be comparatively rare, but generally the violence offered transmits its momentum so speedily to the joint, that the muscles of the scapula are taken by surprise, and have not time to adjust properly the glenoid cavity. In the depression of the os humeri, the parts constituting the shoulder joint are in their most natural and easy posi- tion. The capsular ligament becomes very loose below, and is somewhat stretched above. Any degree of force which might be applied to the member, is warded off and its direc- tion changed by the intervention of the trunk of the body. Should, how*ever, the force be applied directly in the axis of the bone, the projection of the acromion process, and the strength of the triangular ligament of the scapula, would arrest the dislocation. When the os humeri is advanced, the posterior part of the capsular ligament is put upon the stretch, but the form and arrangement of the articular surfaces are somewhat favour- able to this position, and accordingly it is one of but little inconvenience. When the os humeri is retracted, its head by being directed forwards, exercises considerable force upon the fore part of the capsular ligament, and when assisted by an external momentum is disposed to dislocation, forwards and inwards. The motion of circumduction is very extensive in the shoulder joint; and by it the os humeri describes a cone, of which the glenoid cavity is the apex. It is a regular suc- cession of the movements already mentioned, and in consc- £■■ 'iff-. MOTIONS OF THE FORE-ARM. 2YI quence of all t^he motions forwards of the os humeri being more easy and natural, the axis of the cone instead of being directly outwards is somewhat forwards. By rotation, is meant the revolving of the os humeri upon itself. The centre of this movement is not the axis of the bone, but is removed to one side of it, by the lateral projec- tion of the head. The neck, however, is too short and thick to permit any great extent to this motion, it accordingly is limited in such a way as never to amount to luxation. Its greatest extent in most persons ddes not exceed the describing of half a circle, which may be ascertained by applying a finger upon the internal condyle of the humerus. By it the capsular ligament is rendered alternately loose and tense on its front and back parts,. Bichat observes, that in the an- chylosis of the elbow joint, this motion by habit is much augmented, so as to supply the want of rotation of the head of the radius upon the ulna. The scapula and the clavicle do not vary their position in rotation. SECT. IX.—OF THE MOTIONS OF THE FORE-ARM. There are two kinds'of motion in the fore-arm. In the one, the fore-arm is flexed, or extended upon the arm, and in the other, the radius only changes its position in regard to the ulna. , l.The ulna is the essential agent of the first in conse- quence of its manner of articulation with the os humeri, the radius is only accessary, and is drawn by the ulna into a participation in its motions. These two bones, it will be re- collected, are disposed of in an inverse manner, the larger part of the ulna being above, while the larger part of the radius is below. This arrangement causes the ulna to pre- sent the principal articular surface for union with the qs humeri, while the radius affords the principal surface to the carpus; it also gives to the whole fore-arm a great uni- vol. i.—e e 21b SKELETON. formity, in its transverse diameter. The fore-arm executes upon the arm flexion, extension, and lateral inclination. Where the flexion is complete, the coronoid process is re- ceived into its cavity, on the front of the humerus-; and the olecranon having left its cavity is placed below the condyles. In this state the capsular ligament is stretched at its*f>Qste- rior part, while the anterior is thrown into folds, and is re- laxed along with the lateral ligaments. In the demiflexion of the arm, there is a more equal degree of tension of the several ligaments. When the os humeri is reposing in its most easy attitude at the side of the body, if the fore-arm be flexed, its line of motion directs the hand towards the mouth, a circumstance which is accounted for by the peculiar ob- liquity of the trochlea, on the lower part of the os humeri upon which the ulna revolves, and is independent of any spe- cial act of volition. It is said, that man above all other ani- mals, has the mechanism of the upper extremity most par- ticularly addressed to the latter motion, to the perfection of which the clavicle is indispensable. It is in consequence of this application of the clavicle, that if it be'broken; man like animals which are entirely deprived of it, will in the flexions of the fore-arm more easily carry the hand to the opposite shoulder than to the mouth. There is no point in the flexion of the fore-arm which admits of dislocation. In the full extension of the fore-arm, the olecranon process being received into its cavity, is much above the condyles of the os humeri. The lateral ligaments, as well as that part of the capsule on the front of the joint are in a state of ten- sion. When the extremity is in this position, a fall upo*i the hand may produce a dislocation backwards. In this case the fore-arm being fixed,-the coronoid process affords the surface upon which the principal momentum of the fall is felt. If the ligaments on the front of the joint be not strong enough to withstand the force, they are lacerated,' and the articular surfaces passing each other, the upper part of the ulna and radius are driven behind the os humeri. Bichat asserts, that nothing is more easy than to produce such a luxation on the dead body by a similar proceeding, and that MOTIONS OF THE FORE-ARM. 219 he has repeatedly done it—that it is about as easy to, pro- duce this dislocation, as it is difficult to effect one at the scapulo-humeral articulation. In a moderate extension of the fore-arm, produced by a small weight suspended on the hand at arm's length, there is a well marked pressure of the inferior extremity of the humerus against the ligaments in front of the articulation, which is augmented by a tendency of the ulna to describe the arch of a circle, from above down- wards, and to separate itself from the humerus. In this case the muscles which flex the fore-arm are kept so much in the line in which they contract, or are so little removed from the axis of their own motion, that they contribute but little to sustain the fore-arm in situ, the weight is therefore actually sustained by the ligaments in front of the articulation. But they being pressed and drawn in the manner mentioned, such great pain and weariness are produced as to render a con- tinued suspension of the weight insupportable, the experi- menter is therefore in a short time, under the necessity either of casting off the weight or of giving such a degree of flexion to the fore-arm as will allow the muscles to contract more advantageously. Besides flexion and extension the ulna has a sort of rock- ing motion when the fore-arm is only half bent, but when the latter is at either extreme of the former positions, this motion is imperceptible, owing to the nature of the articular surfaces and the resistance of the ligaments. 2. In the rotations of the radius upon the ulna, the latter is almost motionless, excepting the case specified in the last paragraph. The position of the radius on a plane somewhat anterior to the ulna; its small cylindrical upper extremity, and its broad lower one, all concur in facilitating rotations forwards and backwards. It is owing to the hand following these motions that the first is expressed by the term prona- tion, in which the palm of the hand is directed downwards, and the second, supination, in which the palm is upwards and the back «f the hand downwards. Pronation is the most common and consequently the'easiest 220 SKELETON. position to the.fore-arm, when not carried to an extreme; it is adopted involuntarily, simply by the action of the liga- ments and the particular shape of the articulating surfaces of the bones. It is the posture most geneitally suited to the examination and grasping of surrounding bodies. In order that it may be accomplished fully, the superior extremity of the radius rolls on its own axis, in the loop formed by the annular ligament and thedesser sigmoid cavity of the ulna; while the lower extremity revolves around the little head of the ulna below. The middle part of the radius crosses that of the ulna, and the inter-osseous space is diminished. An excess of this motion will produce luxation either above or below, but more easily at the latter place, both on account of the greater extent of motion there and of the comparative weakness of the ligaments. » In supination, a movement the reverse of what is described, takes place, the radius revolves outwardly and is brought parallel with the ulna. If by any force it is carried beyond this line, a dislocation may occur in which the little head of the ulna, abandoning the sigmoid cavity of the radius, will be thrown in front of it. An accident, however, said to be very unusual. Bichat considers the cartilage between the ulna and the cuneiforme as a principal obstacle to these luxations, but when it is insulated or separate from the cartilage of the ra- dius, as sometimes occurs, the joint is very much weakened thereby andjmore exposed to dislocations. SECT. X.—OF THE MOTIONS OF THE HAND. The hand, as a whole, performs upon the fore-arm, flexion, extension, lateral inclination, and circumduction. As it only follows the motion of the radius in pronation and supi- nation, and does not contribute in the slightest degree to either, its appropriate motions can all be performed inde- pendently of them. In flexion the convex head formed by the first range of MOTIONS OF THE HAND. 221 carpal bones, slides from before backwards in the concavity which receives it. The posterior part of the capsular liga- ment is stretched, and the anterior thrown into folds, while the lateral ligaments remain at their ease. In extension, with the exception of the lateral ligaments, the phenomena are reversed. This extension, as is well known, not only brings the hand into the same line with the bones of the fore- arm, but carries it beyond that line till it forms almost a right angle with it. The wrist-joint in this respect differs from the other ginglymous articulations, but what it gains in extension it loses in flexion, as it cannot be bent so much as either the elbow or knee. The arrangement, however, gives great facility to the use of the hand. In the lateral inclinations of the hand the capsule, in front and behind the wrist, is but little affected, but the lateral ligaments are alternately relaxed and tightened. As the articular surfaces are extensive in the line of these motions, dislocations in the direction of either of them are very un- common, and when they do occur they are for the most part incomplete. Circumduction is produced by a regular succession of the motions described, it therefore does not require a specific notice. >Of the Partial Motions of the Hand,—Well marked changes of position occur between the first and second rows of the carpus, these are principally flexion and extension. Lateral inclination or abduction and adduction are extremely limited, and circumduction does not exist. The motions, such as they are, are confined within much narrower limits than those of the radio-carpal articulation, and have for their main fulcrum the head of the magnum. The lateral articular surfaces of the several bones of the carpus, though they present the arrangement of joints, have not an appreciable motion upon each other. Whatever changes of position happen among them, are probably so ob- scure that they never appear, except under the influence ot great and sudden violence. The complexity of the me- 222 SKELETON. chanism of the wrist, seems to have a double object in view; for ordinary circumstances of impulse and motion, the flexion and extension of the first row upon the second, as a whole, is sufficient; but when a great momentum is commu- nicated to the structure, the number of pieces which form it, and the variety of their shapes and mode of attachment, dif- fuse the violence throughout the whole wrist, and generally save it from dislocation or fracture. The fracture of a sin- gle bone, excepting from gun shot wounds, is a very unusual circumstance; I have, however, in possession a scaphoides which was broken through transversely, and had probably been in that state for a long time, as all appearance of inflam- mation at the period of my finding it was absent, and as the fractured surfaces had become highly polished by rubbing against one another. The pisiform bone moves with much freedom inwardly and outwardly on the cuneiform, but its motion up and down is resisted by the muscles which are attached to it. Owing to its articular cavity being insulated, and to its own remote- ness, a dislocation of it, if it did occur, would interfere but little in the general uses of the hand. The Metacarpal bone of the thumb has a Very free motion on the trapezium, in flexion, extension, adduction, abduction; and circumduction, as the result of the other four. In con- sequence of this variety of movement in lt,J of its position on a plane anterior to that of the fingers, and of a corres- ponding obliquity of the trapezium, the thumb can, in all cases of grasping and examining bodies, antagonise the fingers. The circumduction of the thumb resembles very much that of the wrist or shoulder joint though the mechan- ism of the articular surfaces is different; in this motion it describes a cone or circle, the anterior segment of which is larger, and performed with more facility than the posterior. The second and third metacarpal bones are so closely bound to the carpus, that their motion above is almost imper- ceptible ;\ in consequence of their length the motion is more MOTIONS OF THE HAND. 223 appreciable below, but even there it is very much restricted. The fourth metacarpal bone has a limited ginglymous move- ment, which is sufficiently demonstrable, and the fifth has it in a considerable degree; it also admits of a sort of adduc- tion, by which, it is brought nearer to the other bones. The first phalanges admit of flexion, extension, adduction, abduction; and circumduction, by the successive performance of the others. The first phalanx of the thumb has the three last motions very much curtailed, in consequence of the ne- cessity of great strength and stability in this joint, so as to antagonise firmly the fingers. The remaining phalanges perform simply flexion and extension. The latter as in the knee and elbow, rarely goes beyond the axis of the limb, "whereas the former, from the extent of the articular surfaces and the particular mechanism of the joint, permits the hand to be closed and doubled. From what has been said, it will not be difficult to form a general conception, of the great variety of motions resulting from the number and arrangement, of the pieces constituting the upper extremity. The os humeri being the basis of them, may be presented in any direction; the bones of the fore- arm may be alternately retracted or projected, and by the revolving of the radius, will permit the palm of the hand to apply itself at any point; and again the multiplicity of sim- ple motions in the hand, and the exhaustless_ variety of their compounds, contribute to give to the upper extremity in man, a perfection of mechanism infinitely beyond any thing which can be devised by the powers of art. A sentiment cogently expressed by the late Professor Wistar, in the words that ''The human hand, directed by the human mind, is the most perfect instrument that man ever saw or ever will see." Oil SKELETON CHAPTER VI. OF THE INFERIOR EXTREMITIES. The bones of the inferiore xtremities are, the os femoris, the tibia, fibula, patella, and a large number which enters into the composition of the foot. sect. i.—of the thigh bone, (Os Femoris.) This is the only bone in the thigh, and extends from the trunk to the leg. It is considerably the longest and largest bone in the skeleton, and presents a conformation entirely peculiar. For the purposes of description, it is divided into the two extremities and the body. The superior or iliac extremity presents three well marked eminences, the head, the great and the little trochanter. The head is the articular surface above, and forms rather more than one-half of a perfect sphere. Its smoothness indicates the existence of a cartilaginous crust on it during life, and is only interrupted by a small pit a little below its centre, which gives origin to the round ligament of the hip joint. Its articular surface is more extensive above than below, as that part is chiefly employed in sustaining the trunk, and comes in contact with a corresponding surface of the os inno- minatum. The head is supported on a branch of the os fe- moris called the neck, which, projecting from the internal face of the bone between the trochanters, is directed inwards and upwards at an angle of about thirty-five degrees, but varying in different subjects. The neck is two inches in length, oval, or resembling a flattened cylinder, the greater diameter of which is vertical; and arises by an extensive base along the upper end of the os femoris. It has a great mul- titude of foramina dispersed over it, which penetrate to its interior, and give passage to blood-vessels; the largest of THIGH BONE. 225 them are on its posterior surface. Some of these foramina are also occupied by fibres. A superficial horizontal fossa, formed by the tendon of the obturator externus, may be seen crossing the posterior face of the base of the neck. The great trochanter is situated at the superior part of the base of the neck, and though presenting a well marked, ele- vated summit, rising straight upwards, does not reach the altitude of the head, but falls short of it half an inch. The trochanter major rests upon a broad base, has its surface much diversified, is somewhat prominent in front and exter- nally, but presents on the side which is next to the head of the bone a deep rough concavity, which is occupied by the insertion of the small rotator muscles on the back of the pel- vis. On its summit is a small smooth spot, marked by the insertion of the pyriformis muscle; below this, and exter- nally, is a broad surface, slightly convex, into which the gluteus medius is inserted; below this again is a second prominent and rounded surface, over which a part of the ten- don of the gluteus maximus plays. On the front of the tro- chanter, and just in advance of the insertion of the gluteus medius, is an oblong surface, proceeding obliquely down- wards and outwards, into which is inserted the gluteus mini- mus. The trochanter minor is much smaller than the other, and is a conical process, placed on the internal posterior face of the bone, at the lower end of the root of the neck. It receives the common tendon of the iliacus internus and psoas magnus muscle. A broad elevated ridge joins the two trochanters on the posterior face of the bone, and from its middle half arises the quadratus femoris muscle. A much smaller ridge, and by no means so elevated, runs in front from the one pro- cess to the other. The inferior extremity of the os femoris is much more voluminous than the superior, and is divided into two parts, called the internal and the external condyle. These condyles vol i.—r f 226 SKELETON. are of very nearly the same size, but being separated by a notch behind, they are placed somewhat obliquely in regard to each other, and the internal, from being the most oblique, and consequently the most protuberant, also seems to be the larger. If the os femoris be placed exactly vertical, the in- ternal condyle has the appearance of being the longest; but, if it be placed in its natural obliquity, the lower face of the con- dyles is on the same plane. In front the condyles unite to form an articular pulley, on which the patella plays ; this pulley is unequally divided by a vertical depression, so as to have its more extensive surface external. This latter surface is the anterior part of the external condyle, and is much more ele- vated than the internal part of the trochlea, which belongs to the internal condyle. Posteriorly the internal condyle projects more than the external, and both have the articular surfaces there so much elongated backwards and upwards, as to admit of a very great flexion of the leg. Each condyle presents an internal and an external face. The internal condyle has on its internal face a tuberosity, from which proceeds the internal lateral ligament of the knee; its external face forms one-half of the notch which separates it from the other condyle, and at its anterior part may be observed a small depression, from which proceeds the posterior crucial ligament. The external condyle has on its external face a tuberosity also, from which proceeds the external lateral ligament of the knee, and just below it a de- pression for the origin of the popliteus muscle. Its internal face forms the other half of the notch just mentioned, and on the posterior part of this face is a small depression for the at- tachment of the anterior crucial ligament. The inferior face of the condyles is somewhat flattened, the transverse diameter of that of the external being rather longer than the other. The inferior extremity of the os femoris is beset with foramina, large and small, for the passage of vessels and the attachment of fibres. The body of the os femoris begins at the trochanters, and THIGH BONE. 227 terminates in the condyles. It is slightly bent so as to present the convexity of the curve forwards. Its size is gradually diminished to the^piddle, it then begins to enlarge, and con- tinues to augment till it terminates in the large inferior extremity. The body is very nearly round, and departs from that figure only on its posterior face, where an elevated rough ridge is found, occupying the superior two-thirds of the bone, and called the linea aspera. The linea aspera be- gins broad, rough, and flat, on a level with the trochanter minor, it narrows as it descends and becomes at the same time more elevated. Its lower extremity bifurcates into two superficial, slightly marked ridges, one on each side, which may be traced into the posterior extremity of its correspond- ing condyle. Between these ridges the surface of the bone is flattened. In the whole course of the linea aspera, an in- ternal and an external margin is very obvious. The supe- rior half of the latter is occupied by the insertion of the gluteus maximus, and the remainder by the origin of the bi- ceps flexor cruris. This margin also gives origin to the vastus externus. The internal margin of the linea aspera is generally occupied by the insertion of the triceps adductor, and by the origin of the vastus internus. In the linea aspera, near the middle of the bone, is the canal for the nutritious artery, which slants upwards ; occa- sionally one or more canals besides, are found in it for the same purpose. The texture of the os femoris is compact in its body. Its extremities are cellular, with the exception of a thin lamina forming their periphery, and the cylindrical cavity in its middle, like that in all the other long bones, is reticulated. The ossa femoris approach each other very closely at their inferior extremities, but are widely separated at their supe- rior, in consequence of the length of their necks* and of the distance of the acetabula from one another. 228 SKELETON. SECT. II.—OF THE LEG. Two bones form the Leg, the tibia and the fibula, to which may be added the patella, from its attachment to the tibia. Of the Tibia. The Tibia is placed at the internal side of the leg, and extends from the thigh to the foot. After the os femoris, it is the longest and the largest bone in the skeleton. It is divided into the body and the two extremities. The superior extremity of the tibia is oval transversely, and presents an extent of surface suited to the articular face of the two condyles of the os femoris, to which it is joined. It has here two superficial cavities for receiving the ends of the condyles, one of them is internal and the other external. The internal is the deeper and more extensive of the two, and being oval, has its long diameter in an antero-posterior direction. The external besides being smaller and more superficial is more circular, and from the want of elevation in its margins scarcely presents at all the appearance of a cavity. These two cavities, which approach to within half an inch of each other, are kept entirely separated by an elevated triangular ridge, with a broad base, called the spinous process of the tibia. The summit of the ridge pre- sents two tubercles, one at each end, which serve as points of attachment to the semilunar cartilages. The ridge is placed nearer the posterior than the anterior margin of the tibia. Its base in front is depressed by the origin of the an- terior crucial ligament, and just before this is a rough, tri- angular space, extending to the anterior margin of the hone, and covered by fat in the recent subject. Between the ridge and the posterior margin of the bone is a deep depression for the origin of the posterior crucial ligament The circumference of the superior part of the tibia just THE LEG. 229 below its articular surface is flat before, somewhat flat and concave behind, and bulging at the sides. The flatness in front is triangular, having its base upwards and the apex downwards, the latter terminates in a well marked, broad, rough rising, which is the tubercle of the tibia, and serves for the insertion of the tendon of the patella. The concavity behind is made by the popliteus muscle, and slopes from above obliquely inwards and downwards. The projection is greater. on the internal side of the upper extremity of the tibia, and at its posterior part has a depression made by the insertion of the semi-membranosus tendon. The external projection is larger in front than behind ; at the latter point it has a small articular face, looking downwards, for the head of the fibula. The inferior extremity of the tibia is much smaller than the superior. It is terminated by a transverse quadrilateral cylindrical concavity, by which it articulates with the astra- galus. This concavity is narrower and deeper internally than externally, and is traversed from before backwards by a low broad ridge. It is bounded internally by the internal malleolus, a large process of half an inch in length, the fibular side of which is a continuous surface with the cylindrical concavity, and forms part of the joint. The other side of the malleolus is superficial, being just beneath the skin. A shallow groove exists in its posterior part, which transmits the tendons of the tibialis posticus and of the flexor longus digi- torum pedis. Inferiorly the malleolus is notched, or presents a depression, for the origin of the internal lateral ligament, and just before the depression it is elongated into a point. The lower end of the tibia presents before and behind, a slight swell running transversely just above the articular surface. The posterior swell is occasionally slightly marked by the tendon of the flexor longus pollicis. Externally the circumference of the lower end of the tibia presents longitudinally a concavity which is in contact with the lower end of the fibula. This concavity terminates in- 230 SKELETON. sensibly above, but is deep below, where it is bounded be- fore and behind by an elevated point of bone of which the posterior is the highest. The concavity is placed nearly in the vertical line, of the little articular face for the fibula, on the head of the tibia, and at its lower margin, there is frequently a small lunated surface, which is continuous with the articular surface for the astragalus, and is consequently a part of the cavity of the ancle joint. Just above this lunated surface the bone is rough for the origin of short ligamentous fibres, which unite it to the fibula. The body of the tibia commences just below the enlarged upper extremity and terminates near the ankle. In the front view of it, it diminishes continually in descending, in its su- perior two thirds, afterwards it enlarges gradually to the lower extremity; in the lateral view it diminishes downwards almost to the lower extremity. It is slightly bent forwards and is generally prismatic, more particularly above ; one of its faces is internal, another external, and the third posterior. The internal face is rounded, and, with the exception of its upper part, where the flexor tendons are inserted, it is only covered by the skin. Its external face is flat, excepting be- low, where it is rounded and is covered by the muscles on the front of the leg. The posterior face is slightly rounded except at its upper part where it is crossed by a line running obliquely from the articular surface, for the fibula, down- wards and inwards and above this line, is the superficial tri- angular depression for the popliteus muscle. The three sides of the tibia are marked off from each other by ridges of bone. The anterior ridge called the spine or crest, begins at the external margin of the tuberosity for the insertion of the tendon of the patella, and may be traced very distinctly, in the form of an S very slightly curved, almost to the ankle; it is more elevated in its middle. The exter- nal ridge is a straight line running from one extremity of the bone to the other, to it is attached one edge of the inter- osseous ligament The internal ridge is rounded, but also THE LEG. 231 runs the whole length of the body of the bone, being more distinct below. The internal lateral ligament of the knee and the soleus muscle are attached to it; and below, the flexor digitorum longus. Foramina large and small, for blood vessels and fibres, are found on the circumference of both extremities of the tibia. On its posterior face, about one fourth of its length from the head, is a large canal sloping downwards, through which passes the nutritious artery. Its structure, like that of the other long bones, is cellular at its extremities; but compact in the body, and presenting a cavity occupied by cancellated matter. It will now be understood how it articulates with the fibula externally at both ends, with the os femoris above and with the astragalus below. Of ihe Fibula. The Fibula is placed at the external side of the tibia, and extends from the head of the latter to the foot, it is much smaller and not quite so long as the tibia, and is so articu- lated with it as to be on a line with its posterior face. It is to be studied in its two extremities and in its body. The upper extremity of the fibula is considerably enlarged and irregular. It presents, above, a small articular face directed upwards and very slightly concave, by which it joins the corresponding face of the tibia. This surface is bounded behind by a sort of styloid process, into which is inserted the tendon of the biceps flexor cruris. The circum- ference of the bone in advance of this, furnishes attachment to the external lateral ligament of the knee. The inferior extremity of the fibula is also enlarged, being flattened on its tibial side but more rounded externally. This part of the fibula is called the malleolus externus. It de- scends lower than the internal ankle, and is also more pro- minent and large. Its tibial side presents below a small SKELETON. triangular slightly convex articulating surface which reposes against the side of the astragalus; behind, and somewhat below it, is a small rough depression which gives origin to the posterior and to the external lateral ligament of the ankle. Above the articular surface, the bone is rough and slightly rounded where it is received into the side of the tibia, and sends off many short ligamentous fibres to it. The an- terior margin of this extremity of the fibula is thin and pro- jecting ; the posterior surface is flat and broad, and is slightly scooped out into a longitudinal groove, which transmits the tendons of the two first peronei muscles. The pointed ter- mination below, of the malleolus externus, is sometimes called the coronoid process. The body of the fibula extends between its extremities. It is regularly triangular, somewhat smaller above than be- low, thick posteriorly, thin anteriorly, and slightly convex in its length behind. There are three faces to the fibula, one is external, another internal, and the third posterior. The first is semi-spiral, and turned forwards above; its superior third gives origin to the peroneus longus muscle, and the middle third to the peroneus secundus; its lower third exhibits the semi-spiral arrangement which may be traced into the groove on the posterior part of the malleolus externus, and thereby indi- cates the course of the tendons of the peronei muscles. The internal face is directed towards the tibia, it is divided by a low longitudinal ridge into two parts, of which the anterior is the more narrow. The ridge itself, well marked in the middle two-fourths of the bone, is indistinct above and be- low; it furnishes attachment to the interosseous ligament. The space in front gives origin to the extensor proprius pol- licis, and the extensor communis digitorum; and the space behind gives origin to the tibialis posticus. The posterior face is also somewhat semi-spiral, its superior end being out- wards, and the inferior end inwards. The superior third THE LEG. 2SS gives origin to the soleus muscle, and the remainder to the flexor longus pollicis. The angles of the fibula which are formed by the junction of the three surfaces described, differ somewhat among them- selves. The anterior angle is frequently xevy sharp and elevated in its middle half, and below it bifurcates into two ridges, including between them a triangular space, which is only covered by the integuments. The posterior angle is well marked,.and winds so as to be external above, and pos- terior near the foot. The internal angle formed by the union of the internal and the posterior surfaces, is only very well mark- ed in its middle half. The projection of this angle gives to the bone the appearance of inclining inwards towards the tibia, besides which it has actually a little bend in that direction. Near the middle of the posterior face of the fibula a canal sloping downwards conducts the nutritious artery. The cir- cumference of the extremities, like those of the other long bones presents a multitude of foramina for the vessels and filaments of fibres to pass. It is composed in its extremities of cellular or spongy structure, and in its body of compact matter, enclosing a cavity occupied by cancellated structure. Of the Patella. The Patella is a small bone, intermediate to the thigh and to the leg, and placed on the fore part of the knee joint; it is smaller in proportion in females than in males. Its anterior face is uniformly convex and rough, and is studded with a considerable number of foramina for the pas- sage of vessels, and for the attachment of fibres. The course of the longitudinal fibres composing the front of the bone, is also well marked. The posterior face of the patella is an extensive articular surface, divided unequally by a broad longitudinal elevation, which runs from the superior to the inferior margin of the bone. The part of this surface extern nal to the ridge, is the largest and the more concave, and is vol.. i.—g g 2U SKELETON. applied to the trochlea, in front of the external condvle of the os femoris ; while the smaller surface is on the internal side of the ridge, and is applied in the trochlea of the inter- nal condyle. The circumference of the patella is nearly oval, the long diameter being transverse. Its thickness is much augmented above, where it presents a rough, and somewhat unequal flat- ness for the insertion of the tendon of the rectus femoris. Below the bone is thinner, and elongated into a conical point, from which proceeds the tendon of the patella to be inserted into the tibia. Laterally the margins are thinner still. The texture of the patella is cellular, covered by a lamina of condensed bony matter. It is developed in the tendon ol" the extensors of the thigh, and with the exception of its pos- terior face, remains in a state almost entirely cartilaginous. for a year or two after birth. Its base is, therefore, fibrous, in which is deposited, subsequently, the calcareous matter. In its fractures union is effected more frequently by the fibrous base alone, than by perfect ossification. In order to put it into its proper position, turn the point downwards, and apply the greater surface behind to the trochlea of the external con- dyle. The patella is said to be to the tibia, what the olecra- non is to the ulna, and is, therefore, a sort of appendage to it, united by ligament instead of being continuous with it. as is the case with the olecranon. SECT. III.—OF THE FOOT. The foot forms the third section of the inferior extremit}. and is placed at right angles to the bones of the leg. The size of its bones varies much in different individuals, de- pending much upon their modes of life, and so on; it also varies much in the two sexes, being, for the most part, smal- ler in the feimffe. The foot is oblong, narrower behind than before; presents one surface above, which is its back, and another below, which is the sole; a posterior extremity THE FOOT 235 called the heel, and an anterior extremity called the point; also its internal margin is much thicker, longer, and more concave, than the external margin* The foot is divided into Tarsus, Metatarsus, and Toes or Phalanges. Of the Tarsus. The tarsus forms the posterior half of the foot, and is composed of seven distinct bones, which are arranged on a plan, and present features having scarcely a single point of comparison with the carpus. These bones are, the Os Calcis, the Astragalus, the Naviculare, the Cuboides, the Cuneiforme Externum, Medium, and Internum. Of the Os Calcis. The calcaneum, or heel bone, forms almost exclusively the posterior half of the tarsus, and may be readily distinguished by its greater magnitude. Its shape is very irregular. Its greatest diameter is longitudinal; it is also thicker vertically than transversely. The superior face is deeply scooped out, at its fore part, for joining with the astragalus. This portion is formed by two articular surfaces, separated from each other by a rough fossa, which runs obliquely forwards and outwards. The anterior external part of the fossa is deep, broad, and trian- gular ; the posterior part is narrow, is occupied by a liga- ment, and allows the two articular surfaces to come nearer. Just behind the fossa is the first articulating surface, lying parallel with it, being oblong, convex, semi-cylindrical, and looking obliquely upwards, inwards, and forwards. Just before the fossa is the second surface, and which articulates with the astragalus; it is oblong, much smaller than the first, is not unfrequently divided into two by a transverse notch, and is concave. The part of the bone upon which this facet is wrought is called by the French the little apophysis. 23(j SKELETON. In a limited number of observations, I have had occasion to remark, that the face posterior to the fossa is smaller and more vertical in the African than in the European; the os calcis behind it, is also smaller and longer. The upper pos- terior face of the bone is somewhat concave. The under surface of the os calcis is slightly concave lon- gitudinally. It is bounded behind by two tuberosities, of which the internal is larger than the external; they both give origin to the muscles of the sole of the foot and to the apo- neurosis plantaris. There is also a tuberosity bounding the same surface in front, from which arise the ligaments that connect this bone with adjoining ones. The anterior extremity of the os calcis forms the greater apophysis, and is terminated in front by a triangular and slightly concave surface, by which it articulates with the os cuboides. The posterior extremity is convex and rough : into the lower part of it is inserted the tendo-achilles; the upper part is sloping and more smooth, in order to accommo- date this tendon in the flexions of the foot. The external surface of the os calcis is flat, with the excep- tion of a gentle rising in its middle ; it is marked occasion- ally by a superficial groove, indicating the course of the peronei muscles. The internal surface is very concave, and obtains the name of sinuosity ; along it passes the tendons of several muscles from the back of the leg, of which that of the flexor longus pollicis makes a conspicuous groove on the under surface of the little apophysis. Of the Astragalus. This is the next in size to the os calcis, and is placed on the superior part of the latter, between it and the bones of the leg. The astragalusrpresents above, a semi-cylindrical surface. THE FOOT. 237 by which it is in contact with the tibia. This surface is nar- rower, and continued further behind than it is before; is slightly depressed longitudinally in its middle, and consequently pre- sents an elevated margin on either side, of which the external is the broadest and highest. This articular face continues on each side of the bone, and is more extensive externally, where it comes in contact with the fibula or malleolus exter- nus, than internally, where it touches the malleolus internus. The inferior face of the astragalus is traversed by an oblique rough fossa, going from within outwards and forwards, and corresponding in size with that on the upper face of the os calcis. Behind the fossa, and parallel to it, is a deep oblique, semi-cylindrical concavity, suited to the adjoining face of the os calcis ; and before the fossa is a narrow oblong convexity, suited to the corresponding articular concavity of the same bone. When the latter is divided into twTo facets, the concavity of the astragalus presents also two facets, separated by a small ridge. The anterior extremity of this bone is terminated by a convex head, the horizontal diameter of which is the greatest; which articulates with the scaphoides, and is continuous with the surface that rests upon the little apophysis of the os calcis. On the internal side of the head is a small triangular surface, continuous with the others, that rests upon a strong ligament going from the os calcis to the scaphoides. Above, immedi- ately before the surface for the tibia, is a small depression, which, in the flexions of the foot receives the anterior margin of the articular surface of that bone. The posterior extremity of the astragalus is thin, and has a notch or groove formed in it, by the tendon of the flexor longus pollicis. Of the Scaphoides. It is situated at the internal side of the tarsus, between the scaphoides and the cuneiform bones, and has its greatest diameter transverse. Its circumference is oval, broader ^3b SKELETON. above than below, and at its internal side presents a large tuberosity, into which is inserted the tendon of the tibialis posticus. Sometimes the external margin has a small articu- lar face, where it comes in contact with the cuboides. The scaphoides presents behind a deep concavity, which receives the head of the astragalus; anteriorly it is some- what convex, but this surface is divided by small ridges into three triangular faces, for the three cuneiform bones. Of these faces the internal is broader below than above; the others are broader above than below. Of the Cuboides. It is situated at the external side of the tarsus, between the os calcis and the metatarsal bones. Its figure is irregular, but perhaps sufficiently indicated by its name. It is nar- rower externally than internally, and has the posterior ex- tremity oblique. The superior face of the cuboides is rounded, but rough. The inferior face has in its middle a broad elevated ridge, running almost transversely but somewhat forwards. The external extremity of this ridge is marked by a trochlea on which plays the tendon of the peroneus longus ; the tendon is then conducted along a groove between the ridge and the anterior margin of the bone. The internal face is flat, and has in its middle a circular facet where it comes in contact with the cuneiforme externum. The posterior face joins the os calcis, is triangular, and somewhat convex. The anterior face is oblong tranversely, and is divided by a slight vertical rising into two, for articu- lating with the two last metatarsal bones. Of the Cuneiforme Internum. It is placed at the internal anterior extremity of the tarsus, between the scaphoides and the first metatarsal bone, and may be distinguished from the other cuneiforms by its greater size. Its thickest part is below. THE FOOT. 239 The anterior face presents a long vertical convexity, which joins the first metatarsal bone. The posterior face is not so extensive, and is formed into a triangular concavity, having the broadest part below, which joins the internal facet of the scaphoides. The internal side is semi-cylindri- cal, and rough, it is marked anteriorly near its middle by the tendon of the tibialis anticus. The external side is some- what concave, and generally rough, and is marked just be- low its superior margin by two articular facets, of which the anterior is the smaller, and comes in contact with the second metatarsal bone, the posterior from its concave ob- liquity gives a slope to the upper margin of the bone, and is in contact with the cuneiforme medium. Of the Cuneiforme Medium. The middle or second cuneiforme bone is placed upon the scaphoides, immediately on the outside of the cuneiforme in- ternum. It may be distinguished by being the smallest bone of the tarsus. Its figure resembles sufficiently well a wedge, the base of which is above, and the edge below. Its posterior face is slightly concave where it joins the scaphoides; the anterior face is slightly convex, and articu- lates with the second metatarsal bone. The internal face presents superiorly an oblong, slightly convex, and oblique articular facet which touches the cuneiforme internum, what remains of this side is rough for the origin of ligamentous fibres. The external face is somewhat concave, and presents at its posterior part a vertical articular face for joining the cuneiforme externum ; but anteriorly it is rough for the origin of ligamentous fibres. In the articulated foot the lower part of this bone is almost concealed between the other two cuneiforms. Of the Cuneiforme Externum. The external or third cuneiform bone is placed upon the scaphoides, between the second cuneiform and the cuboides. 240 SKELETON. Of the three bones it is the second in size, and is also appro- priately named from its shape. The base is upwards. The posterior face furnishes, on its superior half to join the scaphoides, a quadrangular articular facet sloping out- wardly, below which the bone projects into the sole of the foot. The anterior face is flat, and articulates with the third metatarsal bone. The internal face presents above, two ar- ticular facets, of which the one at the posterior corner is larger than the other, and joins the second cuneiform, the other at the anterior corner is very small, and touches the second metatarsal bone. Below these facets the bone is rough, and gives origin to ligamentous matter. The ex- ternal face, at the middle of the base, forms an angular pro- jection, behind which is a small oval articular surface that joins the cuboides. The remainder of this face is rough for the origin- of the ligaments, with the exception of a very small articular facet at the anterior superior corner, which joins the fourth metatarsal bone. The structure of the bones of the Tarsus is uniformly cel- lular within, the cells being enclosed by a thin lamella of condensed matter. The astragalus is rather stronger and more compact than any of the others. I have seen one in- stance, however, in which it had been separated into two pieces by a transverse vertical fracture, going from the ankle joint to the articulation with the os calcis. The obser- vation was made after it had been boiled, the callus had com- pletely united the two fragments and no displacement had occurred. Of the Metatarsus. The metatarsus succeeds to the tarsus, and is formed by five long parallel bones. They are called numerically, be- ginning on the inner side, or that of the great toe. There are four intervals between them, which are filled up by the interosseous muscles. THE FOOT. 241 Of the First Metatarsal Bone. Placed at the inner side of the foot upon the cuneiforme in- ternum, and forming the base of the great toe, it may be readily distinguished in the separated bones by its greater size and shortness. The posterior extremity presents an oblong articular con- cavity, the greatest length of which is vertical, for joining the cuneiforme internum. The internal semi-circumference of this extremity is convex, while the external is slightly concave or flat; below it presents a prominent tubercle, into which is inserted the tendon of the peroneus longus. The anterior extremity, also called the head, is rounded and convex, forming an articular surface for the first pha- lanx of the great toe. This surface is continued far back below, and presents there for the sesamoid bones, a trochlea with a longitudinal ridge in its middle. The lateral sur- faces of the head are rough and concave for the origin of the lateral ligaments. The body is much smaller than the extremities, and is prismatic. Its internal side is rounded, the external side flattened, and the inferior side concave longitudinally for lodging the muscles of the great toe. Of the Second Metatarsal Bone. This is the longest of any, and may be distinguished from the others principally by that circumstance. The posterior extremity is triangular, the broadest part being above. It presents a surface very slightly concave, almost flat, which rests upon the cuneiforme medium. The circumference of this extremity being flattened laterally is locked in between the internal and external cuneiforms; on its internal side above, is an articular facet where it comes in contact with the cuneiforme internum, and externally it has two articular facets. The posterior one of the latter touches vol- I.--H ll 242 SKELETON. the cuneiforme externum, and the anterior, which is smaller, comes in contact with the third metatarsal bone. These two facets run into each other by an angular rising. The anterior extremity is convex and rounded ; its vertical diameter is more considerable than its transverse, and the articular face which it furnishes to the second toe is con- tinued considerably below, in order to assist the flexions of the first phalanx. Its circumference is rough, and flattened laterally for the origin of the capsular ligament. The body is smaller than either of the extremities, and decreases gradually from behind forwards. It is flattened on each side, and elevated longitudinally above and below inter a ridge. There is a curvature in its length which makes it convex above, and concave below for the lodgement of muscles. Of the Third Metatarsal Bone. This is rather shorter than the second, but has very much the same shape. Its posterior extremity or base, is triangular, has the broadest part above, and articulates with the third cunei- form ; the surface for the latter slopes outwardly. Its cir- cumference is flattened laterally, and presents internally at its superior corner a small face, which articulates with the second metatarsal; externally it also presents at its superior corner an articular facet, which joins the fourth metatarsal. Its body and anterior extremity, do not present any esscn tial points of difference from the second metatarsal. Of the Fourth Metatarsal Bone. It is somewhat shorter than the third, and is placed upon the internal of the two anterior faces of the cuboides. The posterior extremity, or base, is more quadrangular THE FOO'l. 24S than the base of the preceding bones. It presents an articu- lar face to the cuboides which is also square or nearly so. flat, and slopes outwardly. On its sides it is irregular; inter- nally, at the superior margin, it has two articular facets, continuous with each other, but forming thereby an obtuse angle : the anterior joins the third metatarsal; and the pos- terior, which is much the smaller, touches the cuneiforme externum. Below these the surface is rough. The articu- lation with the cuneiforme externum is occasionally deficient, I have observed the latter particularly in the Negro, and it seems to arise from the unusual development of the cuboides. The external surface of the base has at its superior corner an articular facet for the fifth metatarsal bone, and below it an oblique deep fossa, before which is a tubercle. The anterior extremity and the body of this bone, though smaller than those of the preceding, do not present any essen- tial points of difference. Of the Fifth Metatarsal Bone. This is shorter than any of the others excepting the first, and is placed on the front of the cuboides externally. Its base is remarkable, and distinguishes it strongly, by being projected considerably beyond the external margin of the cuboides and forming there a large tubercle, into the su- perior part of which is inserted tke tendon of the peroneus tertius, and into the posterior part the tendon of the peroneus secundus. The base, also, has a triangular flat surface sloping considerably outwards, which articulates with the cuboides. On the internal side is the articular facet, whereby it joins the base of the fourth metatarsal bone. The base is flattened below, rough and somewhat convex above. The anterior extremity is more rounded than that of the other metatarsal bones, but in other respects similar. The body is prismatic, being flat below, flat internally, and slightly rounded externally. x 244 SKELETON Of the Toes. The Toes are five in number and named numerically by beginning at the great one. They each are formed by three bones called the phalanges, with the exception of the great toe, which has but two of them. The phalanges are distin- guished into first, second, and third. In these several re- spects the toes correspond w ith the fingers. Of the First or Great Toe. The first phalanx of the great toe is longer and much larger than any other. Its base is large and forms a deep concavity for receiving the end of the metatarsal bone. Its anterior extremity is formed into two small condyles, for being re- ceived into the second phalanx. This bone is broad and strong, being semicylindrical above and flat below. The second phalanx corresponds in its appearance with the third of the other toes, but is much larger than any of them. Its base is broad and flat, and has two superficial cavities for the condyles of the first phalanx. The anterior extremity is expanded semicircularly and converted into a very scabrous surface, for the firmer attachment of the soft parts about it, and of the flexor tendon. The body of this phalanx is constricted in the middle, rounded above and flat below. Connected with the great toe are two small hemispherical bones, lying upon the trochlea of its metatarsal bone, and imbedded in the tendons of the small muscles which move the first phalanx. They are the Sesamoids, and present supe- riorly an articular surface covered with cartilage which enters into the composition of the joint; and below, a rounded sur- face which has nothing remarkable. The Sesamoid Bones though generally appropriated solely to this joint, are yet frequently found elsewhere. For exam- ple, in the second joint of the same toe—in the first joint of THE FOOT. 245 the other toes—in the articulation of the first phalanx of the thumb, with its metatarsal bone—in the first joint of the fin- gers—in the knee joint, behind each condyle—and, in ad- vanced life, in tendons where they slide upon bones. An- cient luxations give a disposition to their development in the capsular ligaments of the ginglymous joints, of which a very interesting specimen may be seen in the Anatomical Museum. occasioned by an external lateral dislocation of the elbow. Of the Small Toes. Their phalanges bear a general resemblance with those of the fingers, but are neither so large or so long. The first phalanges are successively diminished to that of the little toe, and are almost precisely like each other. Their posterior extremities or bases form a cavity deeper in pro- portion than the fingers, for receiving the ends of the meta- tarsal bones. The anterior extremities are fashioned into two small condyles for forming a hinge-like joint with the second phalanges. The bodies are smaller than the extre- mities, more rounded and narrower than in the fingers. The second phalanges are very short, the extremities being so near each other that the body is of inconsiderable length, particularly as regards the two last, where it forms a mere line of separation. The posterior end has two superficial cavities for receiving the first phalanx, the anterior end is imperfectly fashioned into two little condyles for joining the third phalanx. The third phalanges have a well-formed articular surface for joining the second. The anterior extremity is rough, for the attachment of the adjoining soft structure, and of the flexor tendons. This phalanx of the fourth and fifth toe is frequently very imperfectly developed, being a mere tubercle with an articular face at one end. 240 SKELETON. The structure of the metatarsal and phalangial bones re- sembles that of other long bones. Porous and cellular at the extremities, their bodies are composed of compact lamellated matter, enclosing a cancellated texture. SECT. IV.--OF THE ARTICULATIONS OF THE LOWER EXTREMITIES. Of the Ilio-Femoral, or Hip Articulation. The basis of this articulation is laid by the head of theos femoris being received into the acetabulum. Both surfaces are covered by thick cartilage ; in the former it is interrupt- ed, however, by the depression near the centre, and becomes very thin near the margin ; and in the latter the cartilage is deficient in the whole extent of the rough surface at its lower part. A cotyloid ligament, a fibrous capsule, the round or inter-articular ligament, and a synovial membrane, arc moreover concerned in this joint. The Cotyloid Ligament is a fibrous prismatic ring, which tips the margin of the acetabulum, and thereby increases its depth ; it can only be seen by cutting open the capsule. Its thickness is unequal, being considerable on the anterior third of the circumference of the acetabulum, where it assists in converting the notch into a foramen, but not so much so else- where. Just below the anterior inferior spinous process, the acetabular head of the rectus femoris sends some tendinous fibres to it. Its base is broader than its margin, and is marked off from the articular cartilage, by a line or narrow groove between them. Its acetabular side is covered by the synovial membrane; the other side has the capsular ligament adhering to it; and the third side adheres to the bone. Where it subtends the notch of the acetabulum, the cotyloid ligament is reinforced by additional ligamentous fibres placed beneath it, and going from the upper to the lower end of the notch. These fibres consist of two planes, one internal and the other ARTICULATIONS OF THE LOWER EXTREMITIES. 2£1 external, partly crossing each other, and adhering closely to the cotyloid ligament. The Inter-Articular, or Round Ligament, is a true liga- mentous band, which is attached at the one end to the pit on the head of the os femoris, and afterwards, by a slight dis- section, is easily separated into two fasciculi, of which the lower one may be traced to the inferior end of the cotyloid notch, where, winding around the prominence of bone, it begins to adhere to the ischium ; and continues to do so from that point along the anterior face of the ischium, just below the acetabulum, to a point between the latter and the upper anterior part of the tuber. The other portion is directed towards the superior end of the notch, and is attached there by two extremities, one near the margin of the acetabulum, and the other three or four lines from it within.* The fibres of the round ligament are somewhat intermixed also with those of the ligament subtending the notch. The Capsular Ligament is the strongest in the body, and represents aconoidal sac, open at both extremities, by which it adheres to the bones. It is fixed by its base to the circum- ference of the acetabulum, beyond the cotyloid ligament, and to this ligament itself where the latter subtends the notch. It there embraces that part of the head of the os femoris which projects above the margin of the acetabulum, and de- scends along the neck to its root. It is longer in front: is fixed there to the oblique line which runs between the two trochanters, and behind into the root of the neck, a little in advance of the posterior oblique ridge. Above it is fixed to the neck, just below the rough fossa in the trochanter major; and on the under surface of the neck it adheres, just above the trochanter minor. It is strengthened in several places by processes from the fascia lata femoris, which descend to it between the muscles surrounding the hip joint.f Its thick- • Antonius and Caldani, Tabula IL. f Soemmering, De Corp. Hum. Fabrica, vol. ii. p. 61. 1794. Andrew Fyfe, Compendium of Anat. Philad. 1807. vol. i. p. 179. 24S SKELETON,. ness is considerable, but variable. In front and above, it is remarkably strong, where it is reinforced by a large fasci- culus of fibres coming from the anterior inferior spinous pro- cess of the ilium, and descending longitudinally to the ante- rior oblique line of the os femoris. The internal and posterior portions of the orbicular or capsular ligament are not so thick; it is, indeed, frequently very thin near the posterior ridge ol the os femoris, and has a number of holes in it for the pas- sage of vessels. It is strengthened internally by some fibres coming from the superior margin of the thyroid foramen. This ligament keeps the bones closely applied to each other, and is hy no means so loose as the corresponding one of the shoulder joint. Its fibres are very irregular generally in their course, and difficult to follow. The strength of this articulation depends principally on the muscles which surround it, of which the rectus femoris, and the iliacus interims and psoas magnus united, are in front; between the latter two and the capsule is a bursa mucosa. Within is the pcctineus and the obturator externus ; behind is the quadratus, the gcmini, the obturator internus, and the pyramidalis; ahove and behind are the glutei.* The Synovial Membrane is a complete sac, displayed over the articular surfaces of the bones, and the internal face of the capsule. It is separated from the roughness at the bottom of the acetabulum, by the existence there of a pad of very vas- cular, fine, fatty matter, from which, according to Bichat, it may be raised by blowing beneath the ligament of the notch, at the point where the blood vessels enter. Coming from the * For an interesting account of the connexion of this capsule with the fascia femoris, see Anatomical Investigations, by J. D. Godman, M, D. Philad. 1324. The author, in following the sheaths of the muscles, or, in otlier words, the processes of the fascia lata, between the muscles, to the capsule, with great attention, has been brought to the conclusion that the capsule is formed entirely from them. He has presented the same views in regard to the shoulder joint, and others. Though not disposed to concur in so general an inference on the source of capsular ligaments, inasmuch as their peculiar texture is opposed to it, and many other circumstances in their anatomical arrangement, I have yet to express great satisfaction in the fidelity with which these connexions of the larger joints have been traced. ARTICULATIONS OF THE LOWER EXTREMITIES. 24,9 acetabulum, it covers the articular faceof the cotyloid ligament, and is then reflected to the capsule, to which it gives a polished internal face, and from which it may be dissected. On reach- ing the root of the neck of the os femoris, it forms small duplicatures, and is reflected upwards along the neck to the head, being separated from the neck by periosteum, or by a fibrous tissue, which Mr. Boyer considers a continuation of the capsule. It covers all the head, except the point of attach- ment for the round ligament, and to the latter it gives a sheath which, at the other end, is continuous with the part of the synovial membrane covering the fatty matter. From the latter circumstance arises a deceptive appearance of the round ligament being inserted into the roughness in the bottom of the acetabulum. Of the Knee Joint. It is formed by the os femoris, the tibia, and the patella, the particular modelling of whose surfaces for the purpose has been described. These surfaces are all covered by a uni- form lamina of cartilage, and are held together by an appa- ratus which for the number of its parts and their arrange- ment, make this the most composite joint in the skeleton. The most superficial layer of the knee joint is the fascia lata of the lower extremity, which in passing down from the thigh to the leg, is so near the cavity of the articulation on each side of the tendon of the patella, that it is by Weitbrecht spoken of under the term of Involucrum Generale. It is here not only a continuation of the fascia femoris, but this fascia is reenforced and thickened by an aponeurosis, which springs from the inferior extremity of the extensor muscles of the leg. The membrane thus formed covers both the pa- tella and its ligament, and extends on each side to the lateral ligaments of the joint, to which it adheres ; it may be traced even behind thein, but there it becomes indistinct, loose, and blended with common cellular and adipose membrane. The involucrum adheres strongly to the internal and external condyles and to the head of the tibia, it has oblique fibres on vol. i.—i i 250 SKELETON the patella, transverse ones on the ligament of the latter, •and longitudinal ones on each side. It is in contact with the synovial membrane of the joint except in the middle portion, where it is separated from it by the patella, and its tendon, and some adipose matter. It may be dissected without diffi- culty from the subjacent parts, by which the ligament of the patella, and the synovial membrane are brought into view. The Ligament of the Patella being situated at the fore part of the articulation, though separated from the extensor muscles by the intervention of the patella, is nevertheless their tendinous insertion into the leg. It arises from the whole inferior margin of the patella, and is inserted into the tubercle of the tibia. It consists in longitudinal, closely compacted fibres, of a character entirely tendinous ; the more superficial of them give a layer to the front of the patella, and in the fracture of the latter sometimes prevent a sepa- ration of its fragments. In front, as just mentioned, it is in contact with the involucrum generate, behind is a large mass of fat placed between it and the synovial membrane of the joint; and on the same surface but lower down, it is in contact with a bursa mucosa fixed between it and the triangular flat- ness of the tibia above the tubercle. A posterior ligament, an internal and an external lateral ligament, two crucial ligaments, two serni-lunar cartilages, and a synovial membrane, compose the remaining apparatus of the joint. The Posterior Ligament is a fibrous expansion on the back of the knee joint, which may be considered as the proper cap- sular ligament at this point, and has its fibres extending ob- liquely from the external condyle of the os femoris to the posterior part of the head of the tibia. It is frequently called the ligament of Winslow, and by the French anatomists is considered as one of the divisions of the tendinous insertion of the semi-membranosus muscle, in consequence of its close connexion with it There arc several foramina or inter- ARTICULATIONS OF THE LOWER EXTREMITIES. 251 ■stices in it, which permit a passage of blood vessels to the fatty matter placed between it and the Crucial Ligaments, and beneath it there are some transverse fibres. The Internal Lateral Ligament is a flattened fasciculus of fibres placed at the internal side of the joint. It arises from the tuberosity on the inner side of the internal condyle and descending vertically is slightly attached to the semi-lunar cartilage, and is then inserted into the superior margin and the internal face of the head of the tibia for two inches or more, increasing in breadth as it descends. On the one side it is in contact with the synovial membrane, and on the other with the involucrum and the tendons of the sartorius the semi-tendinosus and the gracilis. The External Lateral Ligament, placed on the external side of the joint, is nearer its posterior face than the in- ternal ligament. It arises from the tuberosity on the outer face of the external condyle, above and behind the tendinous origin of the popliteus muscle, and is inserted into the ex- ternal part of the superior extremity of the fibula, being covered in almost its whole extent by the tendon of the biceps. Its inner face is in contact with the synovial membrane, and the articular vessels. Its rounded form and shining appear- ance make it look very much like a tendon. The Crucial Ligaments, two in number, are named from their crossing one another laterally, and thereby forming a figure resembling the letter X, or a Malta Cross. They are situated at the posterior part of the articulation between the posterior ligament and the synovial membrane. One of them is called anterior and the other posterior, from their relative situation to each other. The first arises from the internal face of the external condyle, by a depression near the bottom of the notch and just at the margin of the articular surface ; it descends forwards, and is inserted immediately in front of the little ridge between the articular faces of the tibia. The second arises from the bottom of the notch between the con- 252 SKELETON. dyles, just behind the trochlea for the patella, upon a surface that may be considered as belonging to the internal condyle ; it descends backwards and is inserted into the rough surface behind the aforesaid spine or ridge of the tibia. The crucial ligaments are large, round, and composed of parallel fibres very closely compacted; their strength is very considerable, and they serve not only to limit the extension of the leg, but also to check any thing like rotation inwards. The Semilunar Cartilages are two in number; one placed on each side of the superior face of the tibia, between it and the condyles of the os femoris. Their shape is sufficiently indicated by their names, and as they are placed on the cir- cumference of each articular surface of the tibia, leaving the middle uncovered, they increase considerably the depth of the concavities for receiving the condyles. Their exter- nal circumference is broad, whereas the internal is reduced by a gradual diminution of their thickness, to a very thin edge. The internal cartilage is but little more than a semi- circle, and is longer in its antero posterior diameter than in its transverse; on the other hand the external is almost circu- lar ; an arrangement by which each is suited to its respective surface. They adhere by their greater circumferences to the fibrous matter surrounding the joint, particularly the lateral ligaments, but not so closely as to prevent their sliding back- wards and forwards in the flexions of the leg. The tendon of the popliteus adheres to the external, either directly or by the intervention of a small synovial sac. The internal semilunar cartilage is attached by its fore extremity to the anterior internal side of the roughness in front of the ridge on the top of the tibia, and by the hind ex- tremity to the posterior face of the base of the ridge, just in advance of the posterior crucial ligament. The external cartilage is attached by its anterior end, also, to the rough- ness in front of the ridge, but this attachment is considerably behind the corresponding one of the internal cartilage, and is somewhat blended with the anterior crucial ligament; the posterior end is fixed into the posterior face of the ridge, and ARTICULATIONS OF THE LOWER EXTREMITIES. 253 is there between the two crucial ligaments. The anterior extremities of the two cartilages are united by a transverse ligamentous fasciculus aline in tbicknes, which is rather in- constant, but when found, is in front of the anterior crucial ligament. These bodies, though presenting an appearance corresponding with cartilages, on their surface, are neverthe- less formed principally from concentric ligamentous fibres, the character of which is very evident at their extremities. and when they are lacerated. The Synovial Membrane is thin, loose, and delicate, and, as in other joints, is a perfect bag, covering the articular faces of the bones, and reflected from the one to the other. As there is no regular capsular ligament to the knee joint, the synovial membrane is very distinct on each side of the tendon of the patella; and comes in contact there with the fascia lata, as the place of capsule is supplied by this apo- neurosis, along with the several ligamentous fastenings that have been described. The synovial membrane, after cover- ing the articular faces of the tibia, is reflected from their mar- gin upon the semilunar cartilages so as to invest their inferior and superior surfaces, it then ascends to the condyles of the os femoris. It covers the condyles laterally as well as on their articular faces, and leaves thereby half an inch or more of their circumference on each side of the trochlea of the patella, included in the periphery of the joint. The syno- vial membrane, anteriorly, being separated from the ten- don of the patella, by the large mass of fat, then covers the posterior face of the patella, and rising up still further, lines the posterior face of the tendons of the extensor mus- cles for the distance of three inches or thereabouts. The superior end of this reflection is formed into a small pouch, communicating freely with the general cavity, but marked off from it by a partial and variable septum on each side. Some anatomists consider the pouch as a bursa, but it is so seldom seen entirely distinct from the joint, that it answers better to describe it as a part only of the general reflection. The synovial membrane, at the sides of the joint, is in con- 254 SKELETON. tact with the lateral ligaments. Behind it is reflected on the anterior surface of the tendinous origins of the gastrocne- mius, and envelops the tendon of the popliteus, it also invests the crucial ligaments, but in such a way as to leave them out of its cavity. The mass of fat behind the tendon of the patella forms just below the latter, a ridge on each side protruding into the articulation. The external ridge is the Ligamentum Alare minus externum, and the other the Ligamentum Alare majus internum. These ridges converge at their lower extremities, and from their point of union proceeds a duplicature of the synovial membrane, in front of the anterior crucial ligament; the other end of the duplicature is attached to the posterior extremity of the groove in the middle of the trochlea, for the patella. This duplicature is the Ligamentum Mucosum. Of the Peroneo- Tibial Articulation. The tibia and fibula are held together by three places of union, one above—another below—and thirdly the ligament which fills up the space between the bodies of the bones. 1. The Superior Articulation, formed by the upper extre- mity of the fibula and the outer side of the head of the tibia, is entirely disconnected with the cavity of the knee joint, and has nothing in common with its apparatus except the external lateral ligament, which has been described. The articular faces are small and covered with cartilage; an anterior and a posterior ligament, and a synovial membrane hold the bones together at this point. The Anterior Ligament is attached by one end to the front of the head of the fibula, and proceeding upwards and in- wards is inserted, by the other, into the contiguous part of the head of the tibia, before the articular facet. The fibres are separated into fasciculi, leaving interstices betweeen them for cellular substance. The Posterior Ligament is narrower than the anterior, but its fibres are more compact; and like the anterior they ob- ARTICULATIONS OF THE LOWER EXTREMITIES. 255 serve a transverse course, being attached by the one end to the head of the fibula, and by the other to the head of the tibia. The popliteus muscle covers them. This joint is also strengthened by other ligamentous fibres, and by the inser- tion of the tendon of the biceps. The Synovial Membrane is reflected over the articular faces and the ligaments described, and has nothing of par- ticular interest in it. It is said that occasionally the syno- vial membrane of the knee joint runs into it; I have not however seen it under such a circumstance and presume that it is rare. 2. The Inferior Articulation which is formed between the lower extremities of the bones, is not incrusted by carti- lage except very partially, to the breadth of a line at its lower part bordering on the ancle joint. Its Anterior Ligament is broad, and covers the faceof the bones which are in apposition. Attached by the one side to the front of the lower extremity of the fibula, its fibres pass obliquely upwards and inwards to be inserted into the cor- responding part of the tibia. Several interstices exist in it for the passage of vessels, and it is covered by the peroneus tertius. Its lower margin is in contact with the astragalus, and forms a portion of the ankle joint. The Posterior ligament in the arrangement and course of its fibres corresponds with the anterior, being attached by one side to the posterior face of the fibula, and by the other to the corresponding part of the tibia. Like the other its fibres are longer near the ankle joint, than above. Its lower margin is in contact with the astragalus, and is connected with other ligaments coming from the fibula. In the space between the anterior and the posterior liga- ment where the bones touch, they are agglutinated by a short, strong, fibrous tissue, leaving intervals occupied by adipose matter. It contributes much to the solidity and immobility of this articulation. 3. The Interosseous Ligament is analagous to thai in the 256 SKELETON. fore-arm by being a membrane stretched between the two bones. It arises from the ridge on the outer face of the tibia, and is attached to the corresponding ridge on the inner face of the fibula. It is broader above than below, being at the latter point continuous with the fibrous structure which ag- glutinates the bones. Just below the head of the fibula is a large hole for transmitting the anterior tibial vessels, and the origin of the tibialis posticus muscle. It also presents, in its descent, several smaller foramina for the passage of vessels. Its fibres are strong and unyielding, and run ob- liquely downwards from the tibia to the fibula. It is covered in its whole length, both before and behind, by muscles, and serves both as an origin to them and as a means of attach- ment between the bones. Of the Ankle Joint. The articular surfaces here being covered by cartilage as in other moveable joints, are formed by the astragalus being received into a deep cavity made by the tibia and the fibula. The capsular ligament, properly speaking, does not exist either on the front or the back of the joint, and is represented there by a few scattered, loose fibres, on the periphery of the synovial membrane. An internal and an external lateral ligament, with the synovial membrane, constitute the whole apparatus. The Internal Lateral Ligament, also called the Deltoid, arises from the whole inferior margin of the Malleolus Inter- nus, and with particular strength from the depression which exists in it; it then descends and is inserted into the internal face of the astragalus, and into the lesser apophysis of the os calcis which lies just below it. This ligament is broad, thick, quadrilateral; and composed of fibres which de- scend obliquely backwards. The tendon of the tibialis pos- ticus runs in a trochlea which, is formed on the internal face of this ligament. ARTICULATIONS OF THE LOWER EXTREMITIES. 257 The External Lateral Ligament consists in three distinct fasciculi, of which one is anterior, another posterior, and the third in the middle. The anterior arises from the ex- tremity of the malleolus externus, and running inwards and forwards is inserted into the outer face of the astragalus in front of the surface for the fibula. The posterior arises from the depression in the extremity of the malleolus externus, and running inwards and backwards is attached to the point of the astragalus at the outside of the groove for the tendon of the flexor pollicis. The middle arises from the pointed termination of the malleolus externus, and descending beneath the tendons of the peronei muscles, is attached to the external face of the os calcis, below the surface for the astragalus. These fasci- • culi are composed of strong longitudinal and parallel fibres. The posterior is larger than either of the others, and occa- sionally detaches a part which is inserted into the posterior margin of the articular face of the tibia. The Synovial Membrane is reflected as usual over the arti- cular surfaces, and from one bone to the other. It sends up a short process of a line in length between the tibia and the fibula. It is remarkably loose in front and behind, and has on its superficial face a considerable quantity of adipose matter, which cannot be easily detached from it. It com- monly contains an unusual quantity of synovia. Of the Articulations of the Foot. Of the Tarsal Articulations.—1. The Os Astragalus is united to the os calcis by a double articular surface which has been described. The ligaments which hold them to- gether are as follow: The Interosseous Ligament is placed between the two bones, so as to occupy the large oblique fossa between the double articular surface in each. It is a collection of very strong, short fibres, with interstices for fatty matter, which arising from the whole length of the groove in the astragalus, descends to be inserted into corresponding points in the groove vol. i.—k k 253 SKELETON of the os calcis. Where the fossa is narrow, as it is behind, the ligament is thin and flat, but. it augments considerably in front, where there is more room for it. The Posterior Ligament arises from the posterior margin of the astragalus, and descending obliquely inwards is in- serted into the adjacent portion of the os calcis. Its fibres are blended with those of the Deltoid Ligament, and on their pos- terior face they form a ligamentous trochlea for the tendon of the flexor pollicis. This articulation is also strengthened by the insertion of the lateral ligaments of the ankle joint into the os calcis. The Synovial Membrane forms a distinct cavity on the. posterior and larger articular face of the two bones, and is in contact with the fatty matter in advance of the tendo achillis. 2. The articulation of the Astragalus with the scaphoides is formed by the convex head on the part of the former, and by the concavity on the part of the latter. It is covered above by a thin, broad ligament, with parallel and oblique fibres, which arising from the superior and internal face of the as- tragalus are implanted into the upper face of the scaphoides, some of its fibres extending over to the cuneiform bones. It is covered above by the tendons of the extensor muscles of the toes and of the tibialis anticus. On the under surface of the foot this articulation is sup- ported by* two ligaments, called the Calcaneo Scaphoid, Jfrom their origin and insertion. The Interior one arises from the internal margin of the lesser apophysis of the os calcis, and running obliquely forwards and inwards, is in- serted into the under and internal surface of the os scaphoi- des. It is a very thick flattened fasciculus, on the under surface of which is formed the ligamentous trochlese, in which run the tendons of the flexor pollicis and flexor longus digi- torum, and which surface is also in contact with the tendon ARTICULATIONS OF THE LOWER EXTREMITIES. 259 of the tibialis posticus. By subtending the bead of the astra- galus, it contributes largely to the keeping of it in its place in the erect position. The External Calcaneo Scaphoid Ligament placed at the outer margin of the last, arises from the under surface of the greater apophyses of the os calcis, and running obliquely inwards and forwards, is implanted into the under external surface of the scaphoides. It con- sists in two or more short, strong fasciculi. The Synovial Membrane of the articulation betwreen the astragalus and the scaphoides covers the articular faces of these bones, and lines the ligaments above and below, a re- flection of it, also, lines the articulation between the os calcis and the astragalus, in front of the rough fossa which is oc- cupied by their interosseous ligament. 3. The Calcaneo-Cuboid articulation, formed by the two bones indicated in the name, is maintained by two ligaments, one above, the other below, and by a synovial membrane. The Superior Calcaneo-Cuboid Ligament arises from the upper anterior surface of the os calcis, and is inserted into the adjoining upper surface of the cuboides. It is broad, thin, and quadrilateral, with short parallel fibres, and is in con- tact above with the peroneus tertius tendon. The Inferior Calcaneo-Cuboid Ligament,, placed on the plantar surface of the foot, is remarkable for its size and extent. It consists of two horizontal planes of fibres of which the superficial is the longest. The latter arises from the back under surface of the os calcis, and advancing for- wards, its fibres arc inserted into the summit of the ridge which traverses the cuboides obliquely ; the greater part of them, however, go beyond this point and dividing into fas- ciculi are inserted into the base of the third and fourth meta- tarsal bones. The tendon of the peroneus longus is confined between these fasciculi and the under surface of the cuboides. The other plane of this ligament being more deeply seated, is also shorter. It arises from the front under surface of the os calcis, where the tuberosity exists at this point, and by 260 SKELETON. advancing is inserted entirely into the oblique ridge of the cuboides. ♦, The Synovial Membrane being reflected over the articular surfaces of the bones, and lining the ligaments, is uncovered at several places above, where interstices exist between the fibres of the superior ligament, and externally it is conti- guous to the tendon of the peroneus longus. *4. The Scaphoid and the Cuboid bones touch at the ex- ternal posterior angle of the cuneiforme externum, and form there occasionally a distinct articular surface with a syno- vial membrane. Besides this mode of union an interosseous ligament is introduced between them ; on the dorsum of the foot there is a transverse ligament running from one bone to the otlier beneath the extensor tendons; and on the sole of the foot there is an oblique ligament, which arising from the under surface of the scaphoides is inserted into the anterior internal margin of the cuboides. 5. The articular surfaces of the Cuboides and Cuneiforme Externum which are in contact, besides a distinct synovial membrane, are secured by transverse and oblique ligamentous fibres going from the one bone to the other. 6. The Articulation between the scaphoides and the three cuneiform bones is secured by a dorsal and a plantar liga- ment. The former arising from the back of the scaphoides is divided into three fasciculi, that go respectively to the back of each cuneiform bone : of these the internal is the strongest and is particularly well marked on the internal face of the cuneiforme internum. The plantar ligaments are also three in number, and having a sort of common base from the under surface of the scaphoides, by being divided into three fasciculi as above, are inserted into each cuneiform bone. They are not so well marked as the upper ones. The cuneiform bones are also connected together, above and below, by short transverse ligaments going from one bone to ARTICULATIONS OF THE LOWER EXTREMITIES. 261 the other, and holding their lateral surfaces in contact. Those below are not so distinct as the upper ones, and are blended with the insertions of the tibialis posticus. One synovial membrane covers the articular surfaces of the scaphoides and of the cuneiform bones which are in contact; and extends itself by digital processes between the first and second, and the second and third cuneiforms, so as to line also the articulations there. The process between the two latter is much shorter than the process between the otlier two, which extends itself into the tarso-metatarsal articulations, after the same principle which is observable in the hand. Of the Tarso-Metatarsal Articulations. The articular faces of the bones here having been suffi- ciently described, it is to be noted in addition, that besides being covered with cartilage, they have the apparatus of the moveable articulations generally, in ligaments which hold them together, and in synovial membranes. The ligaments are above and below. 1. The articulation of the first metatarsal bone with the cuneiforme internum is one-third of an inch in advance of the next, and completely insulated by its synovial membrane; it is strongly secured by ligamentous fibres above, internally, and below, which give it almost a complete capsule. 2. The dorsal or upper ligaments of the remaining meta- tarsal bones are arranged as follows. There are three for the second metatarsal; one comes from the second cuneiform, one from the first, and another from the third ; the two latter are oblique; and they all converge to be inserted into the base of the bone to which they belong. One dorsal ligament passes from the third cuneiform to the base of the third meta-. tarsal; it is sometimes assisted by a fasciculus from the cuboides. From the superior face of the cuboid bone a fasci- culus is sent to the base of the third and fourth metatarsals. 262 SKELETON. The plantar or under ligaments are arranged on the same plan with the dorsal. Not being quite so strong, they are reinforced by the fibrous sheaths of the flexor tendons which lie upon them. The synovial membrane, which is reflected over the ar- ticular surfaces between the second and third metatarsals and their corresponding cuneiforms, is the elongation of the digital process sent from the scaphoid articulation between the first and second cuneiforms. This process, besides ex- tending to the aforesaid tarso-metatarsal articulations, in- sinuates itself to the articular surfaces on the sides of the second metatarsal bone; but, a distinct synovial capsule is sometimes formed between the base of the third and fourth metatarsals. One synovial membrane is reflected over the surfaces, be- tween the cuboides and the two last metatarsals, and sends in a process between the latter. In all these cases the synovial membranes line the dorsal and plantar ligaments of their respective articulations. Of the Metatarsal Articulations. The metatarsal bones, with the exception of the first, arti- culate w ith each other by the contiguous faces of their roots, which, along with the manner of their getting at these points a lining of synovial membrane, has just been stated. They are further fastened to each other by short transverse liga- mentous fasciculi, which pass from the base of one to the base of the adjoining. These fasciculi exist both on the upper and under surface of the bones, and are therefore denominated dorsal and plantar metatarsal ligaments. There is also a description of interosseous ligaments between the bases of these bones, occupying the space intermediate to the dorsal and plantar ligaments of each. The anterior extremities of the metatarsal bones are not in contact; they are, however, fastened to each other by a transverse ligament on their under surface, the fibres of which DEVELOPMENT OF THE INFERIOR EXTREMITIES. 263 are somewhat blended with the capsular ligaments of the first joint of the toes. Of the First Joint of the Toes. The surfaces of the bones here being covered with cartilage are formed into an arthrodial articulation. There is a fibrous capsule surrounding the articular faces, and enclosing the synovial membrane. This capsule is considerably thick- ened below where the flexor tendons pass over it; above it does not exist, as the extensor tendon is there lined by the synovial membrane; on each side it is also thickened, so as to form a lateral ligament In the under part of the capsule of the great toe, we find on each side the sesamoid bone. These joints resemble so strongly the corresponding joints of the fingers, that further description is unnecessary. Of the Second and Third Joints of the Toes. From the fashion of the surfaces of the bones composing them, these are simply ginglymous articulations. They have their cartilaginous incrustations, synovial membrane, and capsular ligament. The under part of the latter is much thickened, and forms a trochlea for the flexor tendons ; on each side it is arranged into a lateral ligament, and above it is defective, as the synovial membrane is in contact with the extensor tendon. These joints also resemble so strongly thp corresponding ones of the fingers, that further description is unnecessary. SECT. V.—OF THE DEVELOPMENT OF THE INFERIOR EXTREMITIES. The comparatively small quantity of blood which is sent to the lower extremities of the foetus, is the cause of their not being so large in proportion to the upper, at the time of birth as they are subsequently. Our wants immediately after 264 SKELETON. birth, and during the first months of life, are naturally such a9 to require but little service from the lower extremities, in which is seen a striking correspondence between the internal arrangements of the animal economy and its actual neces- sities, or in other words, a continued and rigid adaptation of means to produce a certain effect. The os femoris at birth presents several peculiarities. The superior extremity being in a cartilaginous state, is placed more at a right angle to the body of the bone than it is in the adult. The neck is short, which by diminishing the base of support to the trunk, makes the progression of in- fants more tottering and infirm. The lower extremity is also cartilaginous and large. The body of the bone has but a very slight degree of curvature, which likewise in- creases the difficulty of standing and walking in very young subjects. The patella is cartilaginous. In the leg the bodies of the tibia and fibula are ossified, but their extremities are cartilaginous. The bones of the tarsus, with the exception of parts of the os calcis and of the astragalus are cartilaginous. The metatarsus and the pha- langes are ossified in their middle, but cartilaginous at their extremities ; their development is not so complete as that of the corresponding bones of the hand. About the fifteenth year, the bones of the lower extremity have very nearly the same forms as in the adult, they are all fully ossified, with the exception of the extremities not being fused or joined to their bodies, but still in the state of epi- physes, and therefore separable either by boiling or long continued maceration. Exclusive of this condition, which sometimes remains to the twentieth or twenty-fifth year, the epiphyses are as fully ossified as at any subsequent period of life. MECHANISM OF THE INFERIOR EXTREMITIES. 265 SECT. VI.—ON THE MECHANISM OF THE INFERIOR EXTRE- MITIES IN REGARD TO STANDING. The os femoris is well adapted by its shape and posi- tion for the erect attitude. The curvature which its body makes in front has the effect of advancing the lower part of it, and thereby keeping it in a line with the centre of the trunk ; but if it had been perfectly straight, the erect position would have been maintained with great difficulty, owing to the centre of the trunk being in advance of this bone. Under the latter circumstances an incessant tendency to fall forwards would have manifested itself, which could have been obviated only by flexing the ossa femoris very much at the hip joint, or by keeping one foot always in front of the other. Even under the actual arrangement of the skeleton when muscular sup- port is withdrawn from it suddenly, it falls forwards owing to the weight of the parts anterior to the spine being greater than that of the parts posterior to it. When muscular action is weakened or badly regulated, the same tendency to fall forwards is manifested ; children continually tumble in that direction ; a person in a state of intoxication, somewhat short of the entire loss of locomotion, not being able to sustain the trunk of the body erect by the muscles of the back, inclines forwards, and would be precipitated to the ground, were it not that at this crisis one leg is involuntarily advanced, so that the base of support is much augmented. But if the individual attempts to walk, the continued necessity of keeping a large basis of support to prevent the body from falling forwards, urges him into a slow running or trotting gait. The arrangement of the whole upper extremity of the os femoris is also highly favourable to the erect attitude and to locomotion. The neck of the bone, by its length and oblique position in regard to its body, enlarges transversely the base of its support and gives great stability in preventing the trunk from falling either to the right or left, while it contri- butes at the same time to the facility of progression, in per- VOL. I.—L 1 266 SKELETON. mitting the os femoris to bend forwards and backwards. The lateral or transverse extent of the base, thus obtained, can not be supplied with equal effect in any other way, as a certain proportion between the diameters of the pelvis and the length of the neck of the thigh bone is indispensable. In females where the transverse diameter of the pelvis is greater than in males, though standing is equally secure as in the latter, yet their progression is always marked by a want of firmness strongly characteristic of the sex. The strength of articular connexion of the os femoris with the innominatum, is confirmed by the acetabulum being placed where the latter is reenforced by the linea ilio pectinea, and by the anterior inferior spinous process ; and as the principal weight of the trunk is sustained by the acetabulum immediately below the latter process we accordingly find it at this point of the greatest depth. It has also been stated, that the capsular ligament at this part is stronger than elsewhere, thereby conforming strictly to the general purposes of the articular connexion. The capsular ligament is assisted by the liga- mentum teres, which by arising from the lower margin of the acetabulum and passing upwards to the head of the os femoris, prevents the head from sliding upwards, while it permits it to swing freely backwards and forwards in its socket. In erection the bones of the leg are in a line with the ver- tical diameter of the trunk, in this respect they differ very materially from the os femoris, which not only inclines for- wards in its descent, but also leans towards its fellow inter- nally, and almost touches it at the knee. This relative posi- tion of the leg and thigh is obtained by the greater length of the internal condyle of the os femoris. and also by the other peculiarities of form in the latter; whereas the tibia is nearly straight in the direction of its long diameter, and has a horizontal articular surface above, whereby it and the os femoris make an entering angle externally, and a salient one internally. Under common circumstances the wreight of the trunk is transmitted to the foot exclusively through the tibia, owing to the fibula not entering into the composition of the MECHANISM OF THE INFERIOR EXTREMITIES. 261 knee joint, and not being sustained by any bony basement at its inferior part. The fibula is principally intended for the origin of muscles, and for the lateral security of the ankle joint; and may be broken without the accident suspending either erection or locomotion. The position and shape of the foot concur largely in the general object of maintaining the human being in the erect attitude. Fixed at right angles to the leg and articulated by a surface in the centre of its most solid structure, the tarsus; it receives the weight of the body perpendicularly npon the astragalus. The latter being the key-stone to the arch diffuses the pressure through the remainder of the structure, so that the whole foot is planted against the ground, an attitude more fully executed by man than by any other animal. The tendency of the body to fall forwards, re- quires a very considerable elongation of the foot in front of the tarsus, in order to increase the extent of the base of support in that direction. We accordingly find the meta- tarsal bones not only forming bases for the flexion of the phalanges; but also by their great length, by the flatness of the articular faces which they present to the tarsus, and by their consequent immobility at these points, extending and . securing the base of the body in that direction to which its gravitation most inclines it. The first metatarsal bone though corresponding in place with the first metacarpal, is very unlike it in other respects. Of predominating magni- tude, but parallel with the other bones, and immoveable at its base, it is obviously intended for sustaining the body, and least of all for prehension and for antagonizing the other bones, as is the case with the thumb. The points on which the foot is particularly pressed when we stand, are the tuberosity of the os calcis, the tuber of the base of the last metatarsal bone, with the under surface of the cuboides, and the anterior extremity of the first metatar- sal bone. The arch of the foot, upon which this depends, may he considered in two ways ; one is in the longitudinardi- rection and has its abutments in the os calcis behind, and in the 268 SKELETON. ends of the metatarsal bones in front; the other is transverse, is but slightly elevated externally, indeed almost flat, while it is raised to a considerable height internally. This double arrangement is eminently serviceable in many respects, it permits a concavity in which the muscles of the toes may re- pose and act without being pressed upon by the superincum- bent weight of the body—it also permits a free flow of blood and of nervous energy to this structure, gives a very elas- tic base to the whole body, and allows itself to be applied to such inequalities of surface as it meets with. It has been agitated, by some ingenious inquirers into the original condition of man, whether the erect attitude is natu- ral to him and not the result of an advancement in civilization. Independently of the proofs derived from the authentic re- ports of travellers concerning the varieties of the human family, from none of whom have we reason to believe that the latter have any where been found adopting habitually the attitude of quadrupeds : there are evidences derived from the general mechanism of the skeleton, still more conclusive, that standing is fully natural to us. For examples, 1st. The position of the foramen magnum occipitis evidently further forwards in man than in animals, indicates that his volumi- nous head is to be kept in equilibrium by a vertical line of sup- port near the centre of its base. 2d. The ligamentum nuchas, weak in man. is strong in quadrupeds. 3d. The curvatures of the spine are so varied as to diminish the tendency to fall forward when wre are erect 4th. The direction of the or- bits of the eyes, which, looking forwards when we stand and enabling the eye to apply itself to a vast circumference, would, in the quadruped position, be directed towards the ground, and thereby have the sphere of observation reduced to a few yards. 5th. The opening of the nostrils, when we stand, permits odours to ascend easily into the nose; in the other attitude this opening would be directed backwards. Such are the circumstances, in connexion with the head only, which indicate the necessity of the biped position for the full enjoyment of the functions which the Creator has given to us. MECHANISM OF THE INFERIOR EXTREMITIES. 2g9 But there are also others equally evident in the mechanism of the extremities, and of the parts of the trunk to which they are attached. Thus, 1st The breadth of the pelvis, and the slight obliquity of its superior strait in regard to the spine, prevents us from falling to one side, and at the same time brings the lower extremities immediately in a line with the spine. 2d. The length of the neck of the os femoris and the size of its condyles. 3d. The articulation of the knee which permits the leg to be brought into a line with the os femoris, a position impracticable in quadrupeds. 4th. The foot being articulated at right angles with the leg, and hav- ing its tarsus and metatarsus so well developed. 5th. The predominance of the transverse diameter of the thorax over the vertical, which, with the great length of the clavicle and the shape of the scapula, unfit the latter for assisting much in progression. 6th. The shape of the hand, calculated to seize upon objects, but from the length of its phalanges not suited to sustain the body. 7th. The mode of articulation at the wrist, which, from its mobility and weakness in the direction to which the weight of the body would be applied to it, could not be brought to support it advantageously. And lastly, the great disproportion of length, in the adult, between the upper and lower extremities, when an attempt is made to walk like the quadruped. In considering the skeleton of the very young child, it is worthy of remark how closely its mechanism, with the excep- tion of the head, corresponds with the habits of early life. A spine nearly straight, and a pelvis, the lateral diameter of whose cavity is so small that the transverse base of support is much diminished, render erection inconvenient. Lower extre- mities shorter in proportion than the upper ones, having thigh bones nearly straight; also the articulations of the knee not ad- mitting of a full extension of the leg. All these circumstances prove that the quadruped position, inconvenient and intole- rably irksome when continued for a length of time in the adult, is natural to the young infant. The space between the ossa femoris, produced by the 270 SKELETON breadth of the pelvis and the length of their necks, and there- fore always considerable above, varies below in different in- dividuals. A certain distance at the latter point, seems to be indispensable to convenient and graceful progression. Thus when it is in excess it produces the deformity called bandy legs, and causes a tottering gait, such as may be mi- micked at any time by walking with the legs in a state of abduction : but when diminished it is called knocked knees, and interferes with the firmness of the step by causing the cen- tre of gravity to pass alternately through the internal condyles of the ossa femoris, instead of falling exactly between them. The firmest position in which we can stand is that in which the feet are perfectly straight and parallel with each other, so as to form a square base for the support of the trunk. If from this position the toes be turned either inwards or out- wards, the consequent reduction of the antero posterior dia- meter of the base, causes less resistance to the natural incli- nation of the trunk forwards. Whatever may be the grace and the ultimate intention of the first position in dancing, to wit, that of having the feet nearly in the same line, with the heels touching and the toes outwards, it is certainly the most unfavourable attitude for ease in keeping the body erect that can be adopted, for the base of support being diminished both by the length of the body of the os calcis, and by that of the foot, anterior to the ankle joint the trunk is continually in- clining either forwards or backwards and is prevented from falling only by the alternate action of the muscles behind and in front. When we are upon the knees, the base of support for the trunk being entirely withdrawn in front, it is necessary in order to maintain the position, and to prevent falling for- wards, that the hip joint be flexed so as to throw the weight of the body entirely behind the thigh bones. The position is one of so much restraint and fatigue upon the muscles that it ran be maintained for a long time, only by some artificial MECHANISM OF THE INFERIOR EXTREMITIES. 271 support in front, or by the buttocks falling down upon the legs and resting against them. The position we assume on being seated in a chair, is the easiest of any of those in which the trunk is kept erect or nearly so. The length of the lever represented by the whole length of the skeleton is then diminished one half, consequently any preponderance of it at particular points above, bear with less force upon the base. The base itself is much augmented by the amplitude of the buttocks, and by the horizontal posi- tion of the thigh bones in front; and may be also increased at pleasure by the extension of the legs. If, under such circum- stances, the trunk of the body be slightly advanced, its equi- librium is so easily maintained as to require but a very little muscular action to continue it. The most exposed part of the base is backwards, and if the trunk be kept perfectly erect there is some tendency of it to fall into that direction. Hence the utility of backs to seats, and the fatigue from such as have not. SECT. VII.--ON THE MECHANISM OF THE INFERIOR EXTRE- MITIES IN REGARD TO LOCOMOTION. 1. Of the Motions of the Thigh. These, like the motions of the os humeri, upon the sca- pula, consist in extension, flexion, abduction, adduction, rotation, and circumduction, but in consequence of being per- formed upon an immoveable basis, the acetabulum, they are much less extensive. In order that they may be understood well, it will be useful to assume certain points of reference in the os innominatum and femoris. These are the tro- chanter major, the pubes, and the anterior superior spinous process of the ilium. In standing, the lower external part of the trochanter major, where it forms a bulge on the side of the thigh bone, is on a horizontal line with the upper part of the symphysis pubis. A triangle described, by lines drawn 272 SKELETON. from the anterior superior spinous process to the symphysis pubis—from the latter to the point mentioned of the tro- chanter, and from the latter to the anterior superior spinous process, will be nearly a rectangle, of which the base is above, and the shortest side behind. The Flexion of the os femoris is that motion in which its lower extremity is carried forwards. It is performed with great ease and freedom, in consequence of the arrangement of the articular surfaces of the bones, and of the capsular ligament. The head revolves freely in the acetabulum, the ligamentum teres is put into a slight tension, and the end of the trochan- ter major approaches the sciatic notch. The extreme point of this motion is the one preserved by the os femoris of the foetus in utero. Extension is the reverse of flexion. When the latter has been performed extension restores the thigh bone to its vertical position and carries it some degrees further, but can not be executed to the same extent behind, that flexion is in front. When pushed to an extreme, it brings the trochanter major under the inferior anterior spinous process of the ilium, and the round ligament is put very much upon the stretch ; it is finally arrested by the lower part of the neck of the os femoris lodg- ing against the posterior elevated margin of the acetabulum, and by the thickened part of the capsule in front and above, being so much distended as not to yield further without lace- ration. Abduction is the act by which the thigh bones are sepa- rated. When carried to an extreme the under part of the head of the os femoris leaves the acetabulum, and distends very forcibly the capsular ligament at this point. The supe- rior fasciculus of the round ligament is strongly extended also, the inferior fasciculus is kept easy, and indeed somewhat relaxed. This motion is arrested by the trochanter major striking against the ilium; without which it would be much MECHANISM OF THE INFERIOR EXTREMITIES. 273 more extensive, as the capsular ligament is strained at its weakest point and relaxed at the strongest. Adduction is the reverse of the last. The muscles which produce it, the adductors, from their situation and course are unable to give an extent to this motion much beyond the act of reinstating the thigh when it has been abducted. In this respect they are much less influential than the great pec- toral muscle which adducts the os humeri. The articular surfaces of the bones are suited to a much greater latitude of this movement, but it is arrested both by a deficient power in the muscles, and by the strong upper part of the capsular ligament being put upon the stretch. Circumduction is the regular succession in a circle of the four preceding motions, and is much less extensive in the os femoris than in the os humeri, for the reasons stated. The centre of the circle or cone thus described is the head of the bone, and it is much more extensive anteriorly and exter- nally than posteriorly and internally. Rotation, owing to the length of the neck of the os femoris, is extremely well marked, and is indicated by the trochanter major moving backwards and forwards. The radius of the circle thus described, is the distance between the centre of the head of the os femoris and the bulging external part of the trochanter major. The rotation outwards or backwards is more fully and easily performed than the reverse, owing to the number and favourable position of the muscles caus- ing it, many of which are specially appropriated to its production and some others partially so. This movement is arrested by the neck of the bone striking against the ace- tabulum behind, and by the tension of the capsular ligament in front. Rotation forwards having but few muscles to pro- duce it, and they neither specially devoted to it or acting very advantageously for the purpose, is arrested by the neck of the bone striking against the fore part of the acetabulum, by the tension behind of the capsular ligament, and also by that vol. i.—m m 271 SKELETON. of the ligamentum teres. When the convexity and the neck of the os femoris look directly forwards, it is indicated by the great toe pointing in the same direction. 2. Of the Motions of the Leg. The movement of the leg upon the thigh is that of llexion. extension, and a very partial degree of rotation. In flexion the head of the tibia slides backwards upon the condyles of the os femoris, which are prolonged behind for the purpose of extending this motion. It is checked when carried to an extreme by the posterior margin of the tibia striking against the os femoris, and by the tension of the ligament of the patella. In the mean time the lateral, the crucial, and the posterior ligaments are relaxed. The pa- tella, always stationary and at the same relative distance in regard to the head of the tibia, slides downwards upon the trochlea of the os femoris, and in the flexed position sinks between the condyle so as to come in contact with the liga- mentum mucosum. In extension the patella rises upon the condyles and becomes prominent; the lateral ligaments are rendered some- what tense, and the motion is finally checked by the resist- ance of the crucial and of the posterior ligaments of the ar- ticulation. The rotation of the bones of the leg can only be performed when they are flexed, and the ligaments generally thereby relaxed, in which position a very limited motion inwards and outwards is perceptible. The motion outwards is the more extensive of the two, in consequence of the arrangement of the crucial ligaments, which are separated from each other by it. The motion inwards is limited by these ligaments being brought immediately by it, into close and resisting con- tact with each other. In either case, however, the poste- rior,, and the lateral ligaments, all contribute ultimately to arrest the motion. In all these conditions of the leg the semilunar cartilages slide somewhat upon the head of the tibia. MECHANISM OF THE INFERIOR EXTREMITIES 275 The articulation between the tibia and the fibula is such as to admit of no motion whatever below, but above a limited sliding backwards and forwards is performed by the fibula upon the tibia. This movement is made more perceptible in cases of extreme emaciation and in general relaxation of the muscular system. 3. Of the Motions of the Foot. The general motions of the foot upon the bones of the leg are flexion, extension, and an inconsiderable inclination in- wards and outwards. In flexion, the astragalus rolls backwards in the articular cavity formed by the tibia and the fibula, and is arrested by the anterior upper part of the astragalus coming in contact with the articular margin of the tibia. The ligamentous fibres and the synovial membrane in front of the articulation are relaxed; those behind are in a state of tension, as well as the tendo-achillis, and the other tendons there. Luxation from an excess of this motion is impossible. In extension, the foot is brought with the point downwards, so as to have its upper surface almost on a line with the bones of the leg. The astragalus glides forwards; the tendons on the back of the joint are very much relaxed. The joint itself is in a state the reverse of the preceding, with the exception of the lateral ligaments, which, in both cases, are very nearly in an easy natural position. In the lateral motions the sole of the foot is caused to pre- sent itself either obliquely inwards or outwards, whereby, it may be accommodated to any inclined surface on which we walk. The first position is checked by the internal malleolus, and the tension of the external lateral ligaments ; the second by the external malleolus and by the tension of the internal lateral ligament. These motions constitute the adduction and the abduction of the foot; and, by a regular, succession 276 SKELETON. with its flexion and extension, communicate a very limited and embarrassed species of circumduction. The bones of the tarsus, for the most part, have a very obscure motion upon each other, with the exception of the articulation between the astragalus and the scaphoides, and between the os calcis and cuboides. At these points the movement upwards and downwards, makes a sort of flexion and extension of the fore part of the foot, which is very distinct. A species of twisting, or oblique gliding, is also slightly perceptible there. The bones of the metatarsus are susceptible of* a slight ele- vation and depression, which, almost impercejitible at their bases, become sufficiently obvious at their anterior extremi- ties. They also may be slightly approximated, at their fore parts, by the action of muscles, and by external compression. When the weight of the body is thrown upon them, they sepa- rate from each other, and the metatarsus loses, in some degree, the arched form of its anterior extremity below. The phalanges of the toes have the same motions with those of the fingers, except that they are more restricted. The first ones, therefore, perform flexion, extension, adduction, abduction, and circumduction ; the two last have only flexion and extension. The extension of the first phalanges is more extensive than their flexion, from whence results an important advantage in walking or in standing upon the toes. The shortness of the second and third phalanges of the small toes, together with the thickness of the sole of the foot contiguous to them in their extreme flexion, causes thein rather to be doubled up on themselves than on the sole of the foot. On the General Motions of the Lower Extremities. These may be resolved into three; walking, running, and leaping. MECHANISM OF THE INFERIOR EXTREMITIES. 277 In walking, though the first step may be taken in a variety of relative positions of the lowrer extremities to each other, yet it will make the investigation more clear to sup- pose the individual standing erect, with the two feet precisely on the same plane, and giving equal support to the trunk. The first step is then taken, by detaching the foot of one side from the ground ; in order to do which, the thigh is bent upon the trunk, the leg upon the thigh, and the limb by being thus elevated becomes shorter. At this period the ankle joint re- mains at rest, with a slight inclination of the toes down- wards. By the subsequent relaxation of the muscles of the limb advanced, with an inclination of the trunk to the same side, the limb is caused to descend upon the ground. These are the only motions when the step is short and easy ; but, when a long stride is taken, by which the limb is put very much in advance of its fellow ; in order to bring it to the ground, the pelvis is caused to rotate forwards on the head of the stationary thigh bone, whereby the trunk of the body, instead of presenting the sternum forwards, has it turned to one side. When a step has been taken so as to leave one inferior ex- tremity advanced before the other, for example the left, the limb behind is brought forward by the following mechanism: The left foot, remaining fixed, becomes the point of support to the trunk ; and the right, which is behind, is elevated suc- cessively, from the heel to the toes, by the action of the mus- cles on the back of the leg, and rests upon the phalanges. The effect of this position is to elongate the right inferior extremity to the amount of the distance between the fore part of the ankle joint and the anterior extremity of the metatar- sus, whereby that side of the pelvis is pushed forwards, and a rotation in advance impressed upon it. By the latter im- pulse, the foot of that side is wholly detached from the ground, the thigh being flexed at the same moment at the hip joint, and the leg flexed at the knee, the whole extremity is carried forward and fixed upon the ground, after the manner de- scribed in the first step. Ordi nary progression results, then, from the regular succession o^fee last motion in the two ex- 278 SKELETON. tremities. In regard to the impulsion of the pelvis from ihe foot behind, this will probably take place in every case, more or less; however, it may be reduced very much by a certain extent of flexion at the knee joint; and the want of it not be felt, because other powers concur to produce the same im- pulsion ; as certain muscles, and also the momentum of swing- ing the lower extremity forward. An equality of length in the lower extremities is indis- pensable to graceful and regular progression. If one of them be shortened from any cause whatever, it is manifested in the gait, by an unusual sinking of the pelvis on the de- fective side, at the moment the foot is brought to the ground; and from the continuity of the pelvis with the upper parts of the body, a considerable lateral inclination is communicated to the latter in the same instant. The pains frequently taken to conceal this defect, disguise it very imperfectly, unless the shortness be only such as may be supplied by a shoe with a sole thicker than that of the other foot. Where the short- ness arises from luxation upwards of the os femoris, a crutch is the best substitute for sustaining that side of the pelvis. In running, the position of the feet is somewhat different from what it is in walking; they are extended so as to sup- port the trunk on the phalanges alone, instead of on their soles, whereby a double advantage is obtained, that of keep- ing the lowTer extremities at their greatest possible length, and also of enabling them to detach themselves quickly from the ground. The velocity here is the principal difference between it and walking, yet there are some peculiarities. The trunk of the body is kept continually and largely in- clined forwards, which enjoins the necessity of a quick suc- cessive advance of the lower extremities to prevent it from falling. This position also by advancing the bony points, from which arise several of the muscles used in the extension of the thigb, removes these muscles more from the line of their contraction, and thereby enables them to act more ad- vantageously and promptly* ms each pace on these occasions MECHANISM OF THE INFERIOR EXTREMITIES. 279 is taken to the fullest stretch, the pelvis is rotated forwards from side to side alternately, upon the head of the os femoris, which may be fixed at the time. The face being directed for- wards, whatever rotation in the vertebrae can occur, is then performed. As the pelvis communicates its motions to the trunk, so the latter carries its own to the upper extremities, which are thereby slung alternately backwards and for- wards, and are brought continually to adjust the centre of gravity, which is then more in danger of being lost than in ordinary walking. The ascent of an inclined plane, either by walking or run- ning, is attended with unusual fatigue and difficulty, for the following reasons. In order to advance the thigh it is neces- sary to give it great flexion at the hip joint, the knee must also be bent in an equal degree, and the foot be flexed in or- der to adjust it to the surface against which it reposes. To bring forward the other extremity it requires an equal flexion at the hip and knee, besides which, its heel being below the phalanges, the foot must perform a full rotation at the ankle joint. The difficulty is somewhat diminished by stepping only on the phalanges. As in these cases the trunk of the body, to preserve its equilibrium, must be inclined forward, there are certain acclivities, which, though they furnish a base sufficiently large for the foot, are yet impracticable from not allowing the trunk to be thrown forwards. The descent of an inclined plane is more easy, because it requires but little flexion in the articulations mentioned, to bring the extremity behind on a line with that in front; and its subsequent descent is produced by keeping it almost straight, and shortening the extremity which is fixed. Run- ning is attended with some inconveniences, for the impulsion forwards which this motion communicates to the trunk, as- sisted by the inclination of the plane in that direction, deter- mines a fall inevitably, without a successively accelerated advance of the hind leg. We see frequently in the descent of a very inclined hill, a step, at first guarded and leisurely 2 gO SKELETON. taken, converted unavoidably into a full run, to prevent the body from being precipitated forwards to the ground. In jumping the whole body is projected abruptly from the" ground either in a vertical or oblique direction. In the first the lower extremities are shortened by a gene- ral flexure of their articulations, and by a very sudden and simultaneous extension of them, the resistance of the ground causes the whole frame to mount upwards, till its gravitation causes the momentum to cease, it then descends on the same principle with projectiles generally. In the oblique leap, there is the same flexion in all the articulations of the lower extremities, with the addition of an inclination forwards of the trunk. At the moment when the limbs straighten them- selves, the trunk is projected, not only upwards but forwards, owing to its inclination, and describes in its ascent and de- scent a parabola. In this effort the space traversed will be more considerable, if a previous horizontal momentum has been communicated to the trunk by running several steps be- fore the leap is made. The more oblique the leap is, the greater will be its extent, to effect which the trunk must be inclined proportionably for- wards. But to obtain this inclination without falling, it is necessary for one of the lower extremities to be very much advanced at the moment of springing with the other, so as to convert the motion into a very long step. With this po- sition of the lower extremities a much longer space can be cleared than if they are kept together.* * For a further exposition of these principles of locomotion, see Joh. Alph. Borelli de motu animalium, 1710. Haller Element. Physiol. Tomiv, 1757. Bichat. Anat. Descript. 1801. Barthez nouvelle mechanique des movemens de l'homme et des animaux, 1798. BOOK II. PART X. Of the Integuments of the Body. The integuments of the body consist in the Cellular an<* Adipose Substance, and in the Dermoid Covering. CHAPTER I. OF THE CELLULAR SUBSTANCE. The Cellular Substance (Textus Cellulosus, Mucosus) is an elementary tissue, and is more generally disseminated than any other of the body, for it seems to be quite as in- dispensable to the latter as moisture is to vegetables. It is found abundantly beneath the skin; between muscles; in the interstices of muscles, and of «ther parts; connecting mem- branes to one another; surrounding organs; entering into their composition; gluing them together; in fine, under every variety of circumstance and locality which the human orga- nization admits of. Indispensable as it is to the texture of all other parts; as maybe expected we find it preceding them in the development of the foetus; at which period it is in the condition of a fluid slightly coagulated. When examined with a microscope, as it winds around a muscle and introduces itself between the fasciculi ef its fibres; VOL. 1. —N U 282 INTElil MENTS. it will he seen that however fine the latter may be, yet this* body is interposed between them in thin laminae. On sepa- rating these fibres the intervening laminae are resolved or drawn out into fine filaments, which finally break after being stretched to a certain extent. The lamina which surrounds the whole body of the muscle and constitutes its sheath, on being put upon the stretch, also tears after having been at- tenuated into still thinner laminse and into fibres. If air be blown into the sheath of a muscle, it is distended into a mul- titude of cells of various forms and sizes, which have no de- termined shape, and do not return to the same upon a repeti- tion of the inflation. These cells communicate very freely; all limpid fluids pass with the greatest ease from one to the other, so that from any single point they may, by the force of injection be dis- tributed throughout the body ; this is manifested in emphy- sema, where, from a small wound in the thorax, air becomes universally diffused. Fluids of any kind, except they be inspissated, when deposited in these cells are subject to the common laws of gravity, and continue to descend successively from the higher to the lower cells, as in anasarca. Blood traverses them very readily in ecchymosis. Cellular tissue enjoys a good deal of elasticity, for when stretched it readily returns upon itself. When very thin, as between the fibrillar of muscles, it is colourless or nearly so and of a gelatinous or glue-like consistence; but when its laminae are thicker it is of an opaque white, and has a strength amounting almost to that of ligamentous matter. When dried it becomes crisp and of a dark brown, but may be re- stored to its colour and condition by soaking in water. It is only very slightly affected by the usual heat of the culi- nary processes of roasting or boiling, as our dishes of meat daily prove; but may be resolved into gelatine after a pro- tracted ebullition. Its putrefaction is slow and can not be accomplished, by maceration, under several months. The cellular substance is pervaded by a large number of blood vessels, the majority of which do not, in a natural state, convey obviously red blood, but if any portion of it be CELLULAR SUBSTANCE. 283 exposed for a short time to the air, or to any other unusual stimulus, it quickly becomes suffused with red blood, circu- lating through an infinitude of channels. It cannot however be conceded, as Ruysch supposes, that it is formed exclusively of blood vessels; some anatomists indeed, as Haller and Prochaska, allow that though blood vessels ramify through it, yet they are not spent upon it or do not form a part of its organization. The distinction is rather too subtle to be readily comprehended, and seems, moreover, to be refuted by the continued exhalation and absorption which is going on within it, and by its great pliancy and flexibility. It does not appear that nerves are spent upon the cellular substance, though they pass abundantly through it to their respective organs. It is probable that the granulations on which injured parts of the body depend for their restoration, arise from this cel- lular substance. The late Professor Wistar attended a pa- tient for compound fracture of the leg, with a large wound ; which was subsequently covered with luxuriant granulations. The limb was suddenly attacked with an oedematous swell- ing which extended itself to the sore, and caused its granu- lations to tumefy, so that they pitted upon pressure precisely like other parts.* The most generally received opinion of anatomists,! in regard to the arrangement of cellular tissue is, that it results from the assemblage of a multitude of lamellae, and of fine soft fibres, which, being variously interwoven, produce a series of cells all communicating one with another, but va- rying in their shape and size; so that the whole cellular sub- stance may be considered to represent a single cavity subdi- vided into an infinitude of smaller ones. To this it is object- ed, % that when this tissue is accurately examined, it appears * Syst. of Anat. vol. I. p. 388. f Haller, BSclard, Bichat, Wm. Hunter, &c. $ Bordeu, Recherches sur le Tissu Muqueux et Celluleux. Paris, 1790. I. F. Meckel, Manuel D'Anat. vot. I. p. 105. 284 INTEGUMENTS. rather as a homogeneous, viscid, and only partially solidified substance; particularly in the inferior orders of animals; and in the embryo state of the more exalted, where it has still to admit the deposite or formation of the several organs. That the same is manifest at any period of life, for neither with the naked or assisted eye does it assume any other appear- ance. That its laminated and fibrous condition, when such does appear, is owing to its glutinous or glue-like consistence, which causes it to assume a factitious arrangement upon be- ing drawn or inflated. For example, if one separates two muscles for a short distance, the cellular substance between them becomes unequal and furrowed without losing its cohe- sion, but if they be further separated, filaments and cylin- drical columns are produced. If the traction be then sus- pended and the muscles replaced, the filaments shorten, and are finally united into a consistent mass whose parts all adhere together.* While such tractions are going on, it most frequently hap- pens that air is insinuated into the cellular substance, from which comes the appearance of small cells and vesicles; upon the escape of this air the primitive state of cohesion is re- stored ; and upon a renewal of the traction cells of a different shape, size, and appearance arise. Again, in air so intro- duced, one may push it in any direction, separate its globules, collect them again and into larger masses, vary their shape, and in fact by such means mould the supposed cells into an infinity of forms. From these considerations the inference is plain, that when cellular substance is drawn it must yield itself into filaments; when inflated, as the air acts in every direction, its supposed lamellae must be sepa- rated and assume a cellular shape; and by the application of both forces at once it may be caused to assume both a cel- lular and a filamentous appearance. Upon the whole, Meckel conceives that the term Mucous Tissue, adopted by Bordeu, is much more exact than the one of Cellular Tissue, now most generally used. * F. F. Meckel, loc. cit. CELLULAR SUBSTANCE. iwCM Notwithstanding the perfect continuity of the mucous or cellular substance throughout the body, anatomists for the ease of description have divided it into External and In- ternal. The External Cellular Substance (Textus Cellulosus In- termed ius, seu laxus) has the general extent and shape of the body and of its organs, so that if it were possible to extri- cate the latter from their envelope, it would present a cham- ber for the lodgement of each part. But the walls of these chambers would not all be of the same thickness, as the quantity of cellular substance varies. In the cranium and spinal cavity there is very little of it; on the surface of the head and in the orbits more; about the trunk both internally and externally it is abundant; in the extremities still more so, where it penetrates between the muscles. In the arm pit, in the groin, and in the neck, all parts where much mo- tion is enjoyed, it is unusually abundant. The foramina of the cranium and of the spine, establish the points of con- nexion of the cellular substance of these parts with others adjacent. The cellular substance of the face is continued into that of the neck; that of the latter is continued through the upper opening of the thorax upon the viscera of this cavity; and thence through the opening of the diaphragm. along the great vessels and oesophagus upon the viscera of the abdomen and pelvis. The cellular substance of these cavities is again continuous with the deep seated cellular substance of the limbs, at the arm pit and at the groin. The trunk of the body being enveloped by one broad sheet of cel- lular substance, it is continued superficially to the limbs.* With this general sketch of the distribution and extent of cellular substance, it is not surprising that in certain bad * For a detailed account of the inflections of the cellular substance, the student may consult with advantage, Bordeu, loc. cit. Bichat, Anatomie Generale; SystSme Cellulare. Paris, 1818. Andreas Bonn, de Continuationibus Membranarum, in Sandifort's Thesau- rus Dissertationum, Rotterdam, 1769. Haller, Element. Physiol, vol. i. 1757. 286 INTEGUMENTS cases of emphysema, the air shows itself every where, even ai points the most remote from the lungs, and apparently the least exposed to the accident, as the interstices of muscles, of glan- dular organs, and so on. It will also now be understood how this varied distribution of cellular substance and its protei- form shape, has been the inexhaustible but delusive source of anatomical dicoveries and supposed novelties, under the name of fasciae, sheaths of vessels, and so on; and will continue to be so, to such as do not recollect that all these things are in- cluded under the general character of this tissue, and that each muscle, each viscus, each nerve, and each blood vessel, has its own particular chamber under this multiform arrange- ment, which chamber may be traced to or from any other point according to fancy. At the same time it should be noted thatmanyof the laminae have a condensed form, which renders a special knowledge of them of the greatest use to the sur- geon, and which is elsewhere succinctly pointed out, with the description of their respective organs. Anatomists who lived at a period much less illuminated than the present on the subject of the elementary tissues of the body, seem however to have seized upon the idea of the universal inflection of cellular substance over the surfaces and through the texture of the several organs. Mangetus,* without pretending to originality but in alluding freely to the observations of others, says, " Membrana adiposa, est expansio cellulosa, quae totum corporis habitum, paucissimis, iisque minimis partibus exceptis, circumambit; et in qua ma- teria albicans unctuosa, sensu expers, ad partes fovendas ac lubricandas colligitur.—Haec membrana cellulosa seu pin- guidinosa, non tantum in exterioribus corporis reperitur; sed interus in intestinis, mesenterio, aliisquc prope omnibus partibus, non exceptis etiam vasis sanguiferis, ut suo loco videbimus, observatur." And in describing the aponeurotic covering of the body and of the limbs, which in his day was called Membrana Musculosa, from some false notions of its nature, he adds, " Dicitur oriri a dorsi vertebris, quia sci- * Theatrum Anatomicum, Geneva, 1716, vol. i. Ch. iij. CELLULAR SUBSTANCE. 287 licet earum spinis firmiter adhaeret, inibique multo quam alibi usquam robustior conspicitur. Usus est, musculos uni- versim in sua sede firmare, iisque quasi thecam praestare, in qua ut supra innuimus laxius sibi cohaerente, lubrice moveri queant." The cellular investments of the muscles the same author calls Membrana Musculi Propria, and he speaks of their penetrating between the fasciculi of muscles, and most evidently those of the gluteus maximus and deltoides. The Internal Cellular Membrane (Textus Cellularis Sti- patus) presents itself under different arrangements accord- ing to the organ or part whose interstices it penetrates. As it forms in the muscles an envelope for each fasciculus and fibre, if the latter by any art could be withdrawn, it would represent a congeries of fine parallel tubes. In the case of glandular bodies the internal cellular membrane imitates the shape of their lobes, lobules, and acini or small graniform masses, and may therefore be compared to a sponge. In the hollow viscera, as the stomach and bladder, it unites their successive laminae to one another. In the ligaments even where their fibres are distinct, the latter are united by cel- lular tissue in their interstices. This tissue is not sufficiently abundant in the bones, tendons, or cartilages, to be very distinct; but from what is seen of it in the forming stage of the embryo, it is nevertheless ascertained to be the base of every part. In glandular textures it is frequently spoken of under the name of parenchyma. Most of the membranous textures of the body may by ma- ceration be resolved into this mucous or cellular tissue, so that we hear anatomists without hesitation asserting, that under various degrees of consistence, it forms the skin, the serous membranes, the vessels, the ligaments, in short, al- most every thing excepting the muscles, the nervous system, and the glands, and they only depart from it in having their globules deposited in its interstices.* Meckel even adds to the list the epidermis. • Beclard, Anat. Gen. p. 141. Haller, loc. cit. p, 19. t vol.L p. 113. Ogy INTEGUMENTS. The term mucous tissue was substituted for that of cel- lular, by Bordeu,* owing to its glue-like consistence, and to its resemblance to the corpus mucosum of vegetables; notwithstanding its propriety on these grounds, yet as the lining membrane of all the hollow viscera has the same name, some confusion may be produced without one bears in mind the distinction. Bordeu has expressed the character of the internal cellular membrane very forcibly in saying, that in embryos all their organs are species of buds, which vegetate in the cellular tissue, like plants do in the open air or their roots in the ground, and that each one having an apartment of its own, this apartment is to it a cellular atmosphere, which keeps it in a perfect relation with the action of the organ, f In tracing many of the laminae of the cellular substance, we find, that as life advances, they assume a more fibrous character than what they possessed in infancy; this also oc- curs when they are pressed upon by tumours, or irritated from many other causes. This disposition of the cellular substance to assume a ligamentous character in many of the attachments which are formed between the two tissues, fre- quently leaves it doubtful with which the membrane under examination should be classed ; in some individuals the fibrous substance is predominant, and in others the cellular. This deposite of fibrous matter into cellular substance, or rather the change of the latter into it, may be compared to the partial or even perfect conversion of the cartilages of the thorax into bone by an increased deposite of the phosphate of lime. It perhaps will be better understood by repeat- ing that the cellular tissue is an elementary one, whereas the ligamentous is composite. In addition to the uses of the cellular substance informing • Loc. cit. -j- Loc. cit. p, 65. Recherches Anatomiques sur les Glands, Paris, 1752. Also, An Exposition of the Phys. and Pathol. Doctrines of Theoph. Bordeu, understood to be from the pen of a learned friend, R. La Roche, M. D., in the North American Medicaiand Surg, Journal, Pkilad. April, 1826. CELLULAR SUBSTANCE. 289 a nidus for the deposite of all the molecules of the body, and in circumscribing each organ, so as to keep it distinct from the contiguous ones of a different character; its elasticity and yielding nature permit it, in the movements of the several parts upon each other, to change its position, and upon the cessation of the active cause, to re-establish itself. Its ex- treme flexibility is kept up by a continued exhalation of moisture from the arteries that ramify through its texture. This cellular serosity, when an animal is recently killed and its internal parts exposed to a cold atmosphere, rises in the form of vapour, and has a particular smell. It is more abundant in certain parts than in others, and, as a general rule, where there is the least adipose matter. Indeed, these two substances seem to exist in an inverse ratio : in a per- son, for example, who has died very fat, the parts are com- paratively dry; whereas, in such as have all the adipose matter wasted by a lingering disease, there is a humidity which quickly disposes to putrefaction ; a fact frequently exempli- fied in our dissecting rooms. The cellular serosity is con- sequently more abundant in the scrotum, in the eyelids, and in the penis. Bichat informs us, that he has satisfied him- self by experiments, of its augmentation during digestion, during heavy perspirations, and after sleep; which will ac- count for the swelling of the eyelids, so commonly observed in the morning, upon rising. This serosity is albuminous, as proved by its being coagu- lated by alcohol, and by the mineral acids. It is removed by the absorbents; assisted by the tonic contraction of the cellular membrane, according to M. Beclard.* The latter author, indeed, goes on to say, that the cellular membrane is the essential organ of absorption, by which the skin and the villosities of the internal membrane of the hollow viscera per- form this function. That the substances introduced through it into the blood-vessels no doubt, in doing so, undergo some * Anat. Gen. p. 149. VOL. I.—O O 290 INTEGUMENTS. kind of elaboration, in the same way that those do which are deposited in its interstices for the growth, repair, and changes of the body. CHAPTER II. OF THE ADEPS. The Adeps, in subjects of moderate corpulence, is found beneath the skin ; between it and the fasciae ; and in the layers of condensed cellular substance which are next to the muscles ; as on the face, the neck, the trunk of the body, the buttocks, the limbs, the palms of the hands, the soles of the feet. In the adult, it is also found between the serous membranes and the cavities which they line, as in the thorax and abdomen ; it is also found between the laminae of these membranes, as in the omenta, mesentery, and so on. It likewise exists between the interstices of muscles; in the bones, and elsewhere ; so that its whole amount is estimated at about one-twentieth of the entire weight of the body. There are, however, certain portions of the body, where its presence would have been very inconvenient, they accord- ingly are destitute of it; to wit, the interior of the cranium, the ball of the eye, the nose, the ear, the intestinal canal, the eyelids, the scrotum, the penis, the labia interna, and the substance of the glands. The adeps is of a yellowish colour, and in a semifluid state in the living body; when after death it has got a few degrees below the standard of animal heat, it becomes some- what solidified, and then appears in small aggregated masses of different shapes and sizes. In chemical composition it differs from all other parts of the body by the absence of nitrogen, and is formed of oxy- gen, hydrogen, and carbon, which render it in animals a very suitable article for candles and lamps. According to CELLULAR SUBSTANCE. 291 the analysis of Chevreul* it consists of two kinds of matter, oleine and stearine, the former of which remains fluid at the freezing point, while, as mentioned, the other becomes solid by a very small abatement of its living temperature. The application of porous paper enables one to separate them in a small w7ay. The adeps, though lodged in the cellular substance, is ac- commodated there under different circumstances from the cellular serosity, and is supposed to be in different cells. This doctrine was first promulgated by Dr. Wm. Hunter,i and upon the following grounds. That certain parts of the cel- lular membrane arc destitute of it; that in persons who have died from dropsy, the portions of the cellular membrane which originally contained fat, have a more ligamentous con- dition than others; to wit, those on the loins next to the skin, more than the stratum next to the lumbar fascia; that water or fluids pass readily from a higher to a lower part of the cellular membrane, either when extravasated naturally, or injected; that oil, when injected artificially, subsides in the same way, and has a doughy or (edematous feel, yielding readily to pressure and pitting, whereas fat never shifts its position simply from gravitation. From these several causes Dr. Hunter adopted the opinion, that the oil of the cellular membrane is lodged in peculiar vesicles, and not as the water of anasarca, in the reticular interstices of parts. This idea has been adopted by Beclard, who says, that the lobules of fat, when examined with a mi- croscope, are seen to be composed of small grains or vesicles, from the one hundredth to the one sixth hundredth part of an inch in diameter, each one having a pedicle furnished from the adjacent blood vessel. That the parietes of the vesicles are so fine as to escape observation, but that he considers them as arranged in the same way with the pulp of oranges, lemons, and such kinds of fruit. These several reasons are so plausible that I cannnot but subscribe to their force and accu- * Annates de Chimie, vol. xciv. f Medical Observations and Inquiries. London 1762 292 INTEGUMENTS. racy, notwithstanding the objections raised from otlier quar- ters of high authority. In the infant the fat is found at the surface of the body chiefly, little or none existing in the interstices of muscles and in the cavities. It is more abundant in the female than in the male, and in both sexes it is removed as life declines. Its uses are indifferently understood. At some points it serves to diminish pressure, as on the hands and feet; at others it fills up interstices; it is also a bad conductor of caloric, and may, therefore, serve in retaining animal heat. But its most general application is to the purposes of nutri- tion, it being one of those forms which nutritive matter assumes previously to being perfectly assimilated. This is very fully manifested in hibernating animals, which being fat in the beginning of their torpid state, return from it quite lean ; and in insects which, during their repose in the chry- salis state, live upon their owrn fat while undergoing the me tamorphosis into the perfect animal.* • B6clard Anat. Gen. p. 170. BOOK II. PART XI. Of the Dermoid Covering. The Dermoid Covering, or tissue of the body, consists in the Skin;—its Sebaceous organs;—the Nails ;—and the Hair. CHAPTER I. OF THE SKIN. The Skin (Pellis, cutis, h^*) is extended over the whole surface of the body and thereby constitutes a complete invest- ment of it. At the orifices of the several canals which lead into the interior of the body, as the mouth, nose, vagina, and so on; it does not cease abruptly but is gradually converted into the mucous membrane of the part, so that it is plainly continuous with it. At certain places on the middle line of the body, the junction of the skin of the two sides is indicated by a change in its appearance, called Raphe; as on the upper Hp ; from the navel to the pubes; on the scrotum, and in the perineum ; in all of which places, in the development of the foetus, the two sides of the body are later in uniting than elsewhere. 294 INTEGUMENTS. The colour of the skin varies in different nations; it is black in the Negro, of a copper colour in the American sa- vage, bronzed or tawny in the Arabian, and white in the Europeans and their descendants. It is also subject to vari- ous shades, from the mixture of these races, and from the in- fluence of climate; its general tendency being to turn dark on parts exposed to the influence of tropical heat and light. The external surface of the skin, or that which is free, has on it a great multitude of wrinkles; some of them de- pend upon the subjacent muscles, as on the forehead and face; some are caused by the flexions of the articulations, and are to be seen at all of these places on the limbs ; in ad- dition to which, when there is much emaciation of the parts beneath; the skin, not having sufficient elasticity to accommo- date itself to their state, is thrown into other wrinkles and sometimes into loose folds. Finer wrinkles of another de- scription are also found on the skin, arranged into various angular and spiral directions: they depend on an entirely different cause, which will be treated of elsewhere. This surface also abounds in hairs, which vary in fineness and in length according to the region over which they are distri- buted: it likewise presents many small pits, or follicles, which are the orifices of sebaceous glands ; a finer description of pores, which are visible only to the assisted eye, are supposed to be the orifices of exhalants and of absorbents, but this is not quite certain. The internal surface of the skin is connected to the subja- cent parts by cellular tissue, which permits a considerable sliding of it backwards and forwards, on most parts of the body; on others, however, this is restrained, as on the cranium, the palms of the hands, and the soles of the feet. Since the first observation of Malpighi, on the tongue of a bullock, whereby he ascertained that its integuments consisted in three layers : and the discovery of a similar arrangement on other portions of the integuments, by Ruysch ;* anatomists have, for the most part, admitted the skin to consist of three lami- nae, the Cutis Vera, the Rete Mucosum, and the Cuticula. * Thesaurus anat. IX. THE CUTIS VERA. 295 SECT. I.—OF THE CUTIS VERA. The True Skin (cutis vera, derma, corion) is the deepest, or the layer next to the cellular substance. Its thickness varies according to age, sex, and the region of the body over which it is stretched; on the trunk it is thicker behind than it is in front; on the limbs, thicker on their external than on their internal faces or semi-circumferences. On the mammas, the penis, scrotum, and external ear, its tenuity is remark- able. When uninjected, it is perfectly wdiite in people of all complexions, and in the living state has a semi-transparency that permits the blood of the veins to be seen beneath it. The internal surface of the true skin is so blended with the cellular substance, that in the recent subject there is a diffi- culty in distinguishing where one terminates and the other begins, yet they may be separated by maceration so as to de- termine this line ; mortification of the cellular substance sometimes does the same thing; and in the bam, cured by salting and smoking, the corion, after boiling, may be stripped off with but little difficulty. In either of these cases the in- ternal surface of the latter is seen to be studded with small areolar depressions, caused by the projection of the granu- lated masses of adeps; the margins of those alveoli are the principal points of adhesion to the subcutaneous cellular tissue, while their bottoms are pierced with small openings, that lead through the corion. The external surface of the true skin is covered with very fine papillae or villi, (Papillae Tactus,) that are readily brought within the observation of the naked eye, by maceration when protracted long enough, to permit the separation of the cuticle. The projections on the tongue are very similar to them, and the whole are designated as the papillary body. The cuta- neous papillae are particularly distinct at the bulbous ends of the fingers and toes, upon the palms and soles, on the lips, on the glans penis, and the nipple; in other parts they are 296 INTEGUMENTS. not so evident, but still there can be no doubt of their exist- ence, from analogy. On the hands and feet they are arranged in double rows or files, which occasion the semicircular and spiral turns of small wrinkles or ridges at the ends of the fingers and toes; and the transverse, oblique, and curved ones on other parts of the soles and palms. The small, tri- angular, lozenge-shape, and multangular elevations of the cutis vera, seen elsewhere on its external surface, are caused rather by its contraction than by the papillae. The papillary projections resemble very much small conoi- dal, cotton-like filaments, standing up the twelfth of a line, or thereabouts, from the surface of the skin ; they are by no means so long as the villi of the intestines, and like them con- sist in very delicate ramifications of nerves and blood vessels united by cellular tissue. In places where these papillae are less abundant, the corion is not so vascular or sensitive. They readily receive a fine injection, and if the cuticle be afterwards separated by maceration, their vascularity is very distinct; their nerves are destitute of neurileme.* The texture of the true skin is fibrous; the fibres which com- pose it, by their irregular intermixture, resolve it into a mass of network or areolae, the meshes of which are sufficiently large in some parts to permit the introduction of the head of a small pin. The meshes though they are larger and more distinct on the internal than on the external surface of the true skin, open however upon the latter surface; having passed through the skin obliquely, after the manner of the ureters through the coats of the bladder. Those intervals between the fibres of the skin are rendered very obvious after a maceration of a month or two, or after a skin has been tanned. They serve to transmit hairs, blood vessels, nerves, absorbents; and exhalant vessels also, if such exist. These interstices com- municate freely with the cellular substance, for in many cases of anasarca, blisters when made upon a depending part, empty the cellular membrane of water almost as quickly as * Beclard, Anat. Gen. THE CUTIS VERA. 297 scarifications ;* h't if the blisters inflame, they discharge in- consi -h'rablv, owing to the porosities being shut up by the tumefaction and fulness of the parts. The same is observ- able iti scarifications. A fine injection, when forcibly driven into the extremities of a foetus, will become cxtravasated between tin1 cutis vera and cut'' le, and raise up the latter in small blisters as I have frequently experienced, though it cannot be caused to pass through the cuticle. The precise nature of the tissue which composes the true skin is not yet ascertained; it se^ns, however, to be a mix- ture of cellular substance and ligamentous matter; with a striking predominance of the latter in most parts of the body, though its proportion varies considerably, being very abundant on the thickest parts of the skin, while it is scarcely discernible on the thinnest. The following analogies of dermoid with ligamentous or desmoid tissue are observa- ble : It becomes yellow and transparent on being boiled, and a continuation of the process dissolves it into gelatine: It resists putrefaction for a long time, and is remarkably tena- cious. Contrary, however, to ligamentous matter, it is ex- tensible and elastic, though this property may arise from the oblique intertexture of its fibres ; as a bandage from a piece of muslin, when torn longitudinally or transversely, is ine- lastic, but if it be cut bias, it is then very elastic. The ap- plication of tannin increases its resistance, and makes it one of the strongest animal substances known in human arts. The skin has a very strong power of contraction, which is manifested in an amputation, in a long incised wound, or when a sensation of chilness exists, as in an ague or from the application of cold. Owing to the diminution in size of its areola, its external surface then becomes wrinkled, rough, and studded with projecting points, constituting the Cutis Anserina. * W. Hunter, loc. cit. VOL. T.—r p 298 INTEGUMENT* SECT. II.—OF THE RETK MUCOSUM- The Rete Mucosum* of Malpighi, is the second layer of the skin, and is that in which resides the colour of the seve- ral races of men. It covers every part of the surface of the cutis vera; its existence, however, is not so obvious beneath the nails and about the junction of the skin with mucous membranes, as it is elsewhere; though, taking all things into consideration, it is probable that it exists also at these seve- ral places, but much finer. It is so extremely thin, and of such a soft mucilaginous consistence, that it is very difficult to separate it as a distinct lamina, either by maceration or by any other means ; for it most commonly peels off by ad- hering to the cuticle, after the manner of a pigment, and can be removed from it by ablutions. I have, however, in a pre- paration of Mr. John Hunter, seen it fairly raised as a mem- brane ; and separated for a certain distance from the other two coats of the skin. Fine as this membrane is, it would seem, from the observa- tions of M. Cruikshankf upon a negro dead from small pox, and on an injection executed in London, by the late Dr. Baynham, of Virginia,^ and from more recent experiments in Paris, by Mr. Gaultier,§ that it consists in several layers. 1st. Upon the inequalities or papillae of the cutis vera, there is a layer called, by Mr. Gaultier, bloody pimples (Bourgeons Sanguins) but which, in the opinion of some other anatomists, are only the papillae themselves of the cutis vera. 2d. Then there is a very thin and transparent coat called, from its co- lour, Tunica Albida Profunda; it is especially visible in the negro, under the coloured horns and scales of animals, and * Caldani, Icon. Anat. PI. xr. xci. Albinus, Annot. Acad. Leyden, 1756. Ru\scli,Thes. Anat.ix. \ Expts. on i'erspiration. London, 1795. $ Wistar's Anat. Vol. I. p. 394. S Recherches sur la peau, Paris, 1809; in Anat. De L'Hommr, par J Clo- 'l^t, pl.CXTII. THE RETE MUCOSUM. 299 beneath the nails of white persons. 3d. Over this layer is spread another, (the Gemmula) which contains the colouring matter of the several complexions of the human family, and consists in a multitude of dark brown points in the negro : it is visible, also, in those forms of disease called ephelides by the French, where the skin becomes spotted; it is not so dis- tinct in the healthy state of the white individual. 4th. The last lamina of the rete mucosum, is called, by Mr. Gaultier, Albida Superficialis, from its whiteness and superficial situ- ation ; in many animals it is very distinct, in the negro some- what so, but in the white it is not to be seen except under the nails, about the hair, and under accidental horny excres- cences. These observations of Mr. Gaultier, have been verified by Mr. Dutrochet,* in experiments upon the texture of the skin of vertebrated animals ; and are now generally acknowledged by the French Anatomists. In negroes, in cutting through the skin of the sole of the foot, from heel to toe perpendicu- larly to the furrows, this arrangement is readily recognised ;f and when it has become indistinct from sickness, it may be improved by immersing the skin for three or four days in lime-water, or a solution of potash or barytes, and afterwards keeping it the same length of time in a solution of corrosive sublimate. Blisters also elucidate this point on other parts of the body ; the fluids being locally attracted there infiltrate the corpus mucosum, and separate in part, its layers, to form a vesicle frequently very thick, particularly in fat persons. The scrotum of the negro is also well suited to the exhibi- tion of the rete mucosum, as it is there very distinct, and is universally much thicker and better marked in the negro than in any other race. From its extreme tenuity in the whites its existence in them has by some persons been doubted, but erroneously ; as in them also its changes of colour, from Ihe influence of the sun, is readily demonstrated. There * Journal de Physique, May, 1819. Journal Complementaire, vol v. T J Cloquet, Anat. lie L'llomme, pi. cxvi, fig. 6\ 300 INTEGUMENTS are in fact few persons, perhaps none, so white, but what a slight tinge of yellow exists in their sk'n»s ; which nny be proved by contrasting them with any perfectly white surface. as snow. bleached paper or linen. This slight tinge of yel- low is increased to an olive colour by the sun's rays, and in some instances by a spontaneous deposite ; in other cases, it is in certain spots removed, so as to leave a colour almost perfectly white, or that only of the cutis vera.* When the latter change occurs in the African, it occasions a hideous pie-bald complexion, and the cuticle is readily elevated into blisters, by the irritation of the solar rays. Some persons have an entire deficiency of this pigment on the skin, from birth ; the same deficiency occurs in the eyes and hair : they are designated as albinos. The deficiency of the pigmentum nigrum in the eye, causes it to look red, like that of the white rabbit; and also makes it intolerant of a strong light, as that of noon-day. Anatomists generally have rejected the idea of the vascu- larity of the rete mucosum, yet it would seem to have been injected, on one occasion at least, by the late Dr. Baynham, in a leg which was diseased from exostosis ; and there are now in the anatomical cabinet of the University, three prepa- rations !>y tr.yself, of the fingers of an African, where the colouring matter of the injection has been passed from the papillae of the cutis vera into the rete mucosum ; and there deposited in dots, indicating the former position of the pa- pillae. The pigment of the rete mucosum would seem, for the fore- going reasons, to be continually undergoing a deposition and absorption. When it has been lost by a blister in an African, it is generally restored in a short time afterwards, the same occurs in their cicatrices but requires a longer period. The observations of chemists tend to prove that it is formed principally by carbon. Its apparent use is to de- * A ease of this kind is now in the Philadelphia Aims-House, where the absorption of colour has occurred in spots on the hands of a dark-complexioned European. June 15,1826. THE CUTICLE. 301 fend the skin from the rays of the sun, in illustration of which several ingenious experiments have been executed by Sir Evd. Home.* SECT. III.--OF THE CUTICULA. The Cuticle or Epidermis, is the most superficial layer of the skin, and takes its wrinkles from the closeness of its ap- plication to the true skin. It is a thin, dry pellicle, which can not he separated from the cutis by dissection ; in conse- quence of which we have to resort to the alternate applica- tion of hot and cold water ; to partial putrefaction ; or in the living body to vesicatories. The mode of adhesion be- tween the cuticle and the true skin is not precisely under- stood : the surfaces unquestionably adhere with equal tena- city where there are neither hairs or sebaceous follicles to pin them together, as on the palms of the hands and the soles of the feet; and when by previous management this union is somewhat softened, they part very much after the manner of two sheets of paper which had been recently glued and were almost dry. From this it would appear that the adhesion is universal and not defective at any points. In most parts of the body the cuticle presents itself as a single homogeneal layer, of a thickness uniformly about that of the thinnest Chinese blotting paper. Upon the palms and soles of persons generally, but especially of such as are ad- dicted to heavy labour, and exposed to a continued mechani- cal irritation of these parts ; the. cuticle becomes much thick- ened and laminated, apparently from a successive deposite of it on the skin there. It is transparent, by which the co- lour of the parts beneath is readily discernible; in the Afri- can, however, it is extremely difficult, nay, impossible to clean it wholly of the colouring matter of the rete mucosum; it seems indeed as if it were, according to the opinion of some, impregnated by it. The structure of this body is en- * Philos. Transact. London, 1821. c602 INTEGUMENTS entirely peculiar, there is no evidence whatever of the exist- ence of vessels in it: on the contrary, in inflammations wlien the skin becomes of the deepest tinge of red, the epidermis never has its colour changed in the smallest degree; but keeping aloof from this symptom, the impression made on it is manifested by its dropping off, while another layer is pre- paring to take its place. Dr. W. Hunter, though he disbelieved in the possibility of injecting the cuticle, and did not admit the evidences of the preparations of his time having that reputation ; yet thought the communicating or perspiratory vessels might be exhibited in a different manner, that is, by macerating for a short time a piece of the sole of the foot: afterwards, in separat- ing the cuticle from the cutis vera, as the two membranes parted, these vessels would be found in the angle of separa- tion passing from one to the other like cob-web filaments.* There can be no doubt of the accuracy of this statement, for it is easily verified by any one who will take the trouble to perform the experiment; yet it is more than probable that Dr. Hunter was deceived in the nature of these filaments, and that as M. Beclard has suggested, they were merely the threads formed out of the rete mucosum, which was rendered a viscous fluid by the commencement of putrefaction ; and therefore when parted would put on the same filamentous ap- pearance that half dissolved glue does in a similar situation. Some of the aforesaid filaments also are supposed by Bichat and Chaussier to be absorbents, but this opinion of course sinks with the objections brought against Dr. Hunter. Neither is there any evidence of the existence of nerves or of any cellular membrane in this tissue, for it is in all states entirely devoid of sensibility, and never puts forth granula- tions. The excrescences which belong to it, as corns and indurations ; are like it, laminated, owing to their thickness, and have no interior circulation; and though sometimes painful, are so only by their pressing upon the subjacent nerves of the skin. It is also destitute of fibres. * Med. Obs. and Inquiries, vol. ii. p. 53, London, 1762 THE CUTICLE. 3Uo The cuticle is penetrated by hairs, and by the orifices of the sebaceous follicles and glands ; and according to Bichat, also by the exhalants and absorbents, the several orifices of which, he says, become distinct by holding it between the eye and a strong light. As it, when raised by a blister, docs not allow the effused fluid to pass through any of these pores, it is very reasonably supposed that they are all oblique, and there- fore exercise a valvular office on such an occasion. Or, if ac- cording to the supposition of Mr. Cruikshank the finest pores of the cutis vera are lined by processes from the cuti- cle, the collapse of these processes on the separation of the cuticle will also account for the fact. It seems to be well ascertained at the present time, that as the epidermis is more transparent at certain points than elsewhere, the appearance has been mistaken for porosities of exhalants and absorbents. The cuticle when detached will not allow a column of mer- cury to pass through it, except its weight be so great as to lacerate it; this fact is rather against the doctrine of the pores being visible when examined by permitting the light to shine through, and shows that even those for the hairs and the sebaeeous follicles are stopped by some arrangement or other. Upon the whole, the opinion of organized pores in the cuticle for exhalation or absorption, is not sustained by any direct testimony, and is scarcely admissible upon any principle. At the same time it may be remarked, that the interstices which exist in it would seem to be sufficient to account for any of the phenomena of exhalation or of ab- sorption. The cuticle has but little power of extension and conse- quently of contraction, and tears with the application of a very slight force. It naturally contains so little moisture, that its bulk is only inconsiderably altered by drying. It, like the hair or nails, resists putrefaction so much, that it has been found in burial places, after a lapse of fifty years: When held in water it swells, becomes white, wrinkles more, loses its transparency, and dulls the sensibility of the cuta- neous papillae. It cannot, like the true skin, be readily re- duced by boilin? water into gelatine, and consequently is not 304 INTEGUMENTS. affected by tanning, it indeed retards that process, when left on the proximate surface of the cutis vera. When applied to a fire it burns, like the hair and nails, with extreme facility, owing to the presence of a similar oil in it, and it gives out a very disagreeable odour. The little extensibility of the cuticle causes it to be rup- tured whenever tumours, as warts, &c. rise from the surface of the cutis vera; it is supposed however, not to be entirely deprived of this quality, as it seems to stretch when raised into a blister, though this may arise, in some measure, from the small wrinkles naturally existing in it, being removed. It has not the slightest sensibility, neither is this quality evolved by any condition whatever of it, as it is in tendons, ligaments, and bones, when they become inflamed. There is, in all probability, a slow loss and reproduction of the cuticle constantly goingon. The formcris manifested by the large quantity of branny scales that are detached from its surface, when one has abstained from bathing for a long time. This is more remarkable on the palms and soles than else- where, and the loss must of course be continually supplied. It, as is well known, is rapidly regenerated when it has been lost simply by an abrasion or blistering, which has not in- terfered with the organization of the rete mucosum. In some cases there is an unusual development of it: Bichat re- tained the skin of a patient, dead at the Hotel Dieu, in whom the cuticle, at the period of birth and in subsequent life, was three times the natural thickness ; and had always, with the exception of that of the face, been subject to a continual desquamation. As the epidermis has in itself no power of regeneration, owing to its deficient organization, the most plausible opinion in regard to its source is, that it is produced by the inspissa- tion and drying of the rete mucosum, which renders it a sort of varnish, well qualified to resist the agency of exterior ob- jects, and to protect the delicate organization of the proxi- mate surface of the cutis vera. This opinion of its ori- gin scejus to be proved by its participating in the colour THE CUTICLE. 305 of the rete mucosum more or less, so as to give it a sensible tinge, which cannot be washed from it. One of the most striking properties of the cuticle is its re- sistance, to evaporation from the surface of the body; in a subject, any part of the skin when deprived of it and exposed to the air dries up in the course of a day or two, while the other portions remain soft and flexible for weeks, and, if it were not for putrefaction causing the cuticle to peel off, would sometimes remain so for months. Though it suppresses evaporation in a great measure, it does not do so entirely; for after a subject has been kept some time, its fingers, toes, nose, and ears get very dry and hard. During life the pro- cess of perspiration is continually going on, either in a sen- sible or insensible manner; and, according to the experiments of Sanctorius, more than one half of the weight of our food is lost in that way through the skin and lungs. MM. La- voisier and Seguin ascertained that the proportionate exha- lation from these organs was as eleven of the former to two of the latter. When the perspiration is rapid it assembles on the surface of the body in the form of small drops, having an acid, saltish taste, and a peculiar odour. In this state, according to the analysis of Berzelius. it consists principally in water holding in solution a hydrochlorate of soda and of potash, some lactic acid, lactate of soda, and a little animal matter. The perspiration, besides its use as an excretion, is a powerful means by its evaporation, of enabling the body to resist a high temperature. It varies both in quality and quantity according to age, sex, state of health, food, and habits of life. The power of the cuticle to absorb or to transmit inwardly articles through it, is not by any means so obvious as its exhalation : the facts however, upon the whole, seem to prove that though this power is much curtailed when compared with that possessed by mucous surfaces where there is no .cuticle; yet it does exist to a certain extent.* • Wistar's Ajnat. vol. ii. p. 396,3d edit. vol. J.—«iq 306 INTEGUMENTS. CHAPTER II. OF THE SEBACEOUS ORGANS OF THE SKIN. The Sebaceous Organs consist in Follicles and Glands. They furnish the oily exhalation, which lubricates the sur- face of the skin, gives linen when worn a long time a greasy appearance, and causes the water in which we bathe to as- semble in drops on tlie surface of the body, rather than to wet it uniformly. This humour produces a rancid disagree- able smell in negroes, and such persons as do not resort to ablutions of the whole skin, from time to time. It is parti- cularly abundant about the places provided with hairs, as the scalp, the genital organs, the axillae, and seems to be in- tended to maintain the flexibility and smoothness of the skin and hair, and to prevent the former from chapping. These qualities of it are possessed in a considerable degree, by the oily articles of the toilet which are used for the same pur- pose. There can be no doubt of the unctuous quality of this secretion, as when collected on a piece of clothing or on blotting paper, it burns with a white flame. Its quantity is readily augmented by certain kinds of clothing, which most persons must have observed shortly after putting on a flannel shirt next to the skin. It is sufficiently certain that the apparatus producing it is not visible to the naked eye in most parts of the skin, so that there would seem to be a necessity of accounting for its appear- ance there, in some other way besides a distinct glandular apparatus. Bichat considered it to arise from a set of exha- lants differing from those which secrete the matter of perspi- ration, a theory by far more rational than that which attri- butes it to the percolation of the subcutaneous fatty matter. M. Beelard, however, admits that sebaceous follicles exist over the whole surface of the skin, with the exception of the palms and soles; because the skin is universally rendered unctuous by this discharge; because many follicles exist THE NAILS. S07 which are only visible to the microscope; and because mor- hid changes frequently render them evident where their ex- istence was not suspected before. In many places these follicles are sufficiently obvious and very numerous, as on the nose, about the corners of the mouth, on the ear and be- hind it, and on the face generally of some individuals. When the skin has been injected, they are found to consist of small pouches placed in its thickness, and having their parietes abundantly furnished in blood vessels. The discharge from them sometimes becomes inspissated and does not readily pass through their orifices, in which case, continuing to accumulate, it will finally form a sensible tumour. Most frequently it does not collect to such an ex- tent, but is indicated simply by a small black point owing to the adhesion of dirt to it; in this condition when squeezed out it assumes a small vermicular shape. The Sebaceous Glands, properly speaking, are about the size of a millet seed, of a light yellow colour, and are placed wherever they exist, immediately under the cutis vera. They are particularly numerous under the skin of the mons veneris. I have not observed them so distinctly elsewhere. CHAPTER III. OF THE NAILS. The Nails (Ungues) supply the place of cuticle on the extremities of the fingers and toes, and may be considered as a continuation of this membrane. They correspond with the talons and hoofs of the lower orders of animals. Each nail consists of a root, of a body, and of a free ex- tremity, or that which projects and requires paring. The root is about one-fifth of the length of the nail, is thin, soft, 308 INTEGUMENTS. and white, and is received into a fold or fossa of the true skin. which is very distinct when the cuticle and nail together are removed by maceration. The concave surface of the nail adheres closely to the skin below, precisely as the cuticle does in any other part of the body, and therefore may be re- moved by the same processes, as hot water and maceration. The white part of the nail at its root is called the crescent (lunula) and is said by Mosely* never to exist in the fingers of Africans or of persons who have even a slight mixture of negro blood. This appearance, however, does not depend upon any peculiar organization of the nail itself at that part, but to the cutis vera below it, which being more vascular elsewhere causes that spot to look white, inasmuch as the nail is semi-diaphanous and permits a view of the circulation be- neath it. This is also sufficiently proved by the fact, that when a nail is torn off its lunula disappears. The nail in- creases gradually in thickness from its root to its end. The nail is covered only on the posterior face of its root by the epidermis, which terminates there in a thin, adherent, diaphanous band ; behind this band the root of the nail pro- jects, and is received into the groove of the cutis vera. The epidermis also adheres to the lateral margin of the nail; and in a line to the concave side of its anterior end. The under surface of the nail is soft, pulpy, and has an arrangement of superficial longitudinal grooves, receiving the papillae of the corresponding surface of the cutis vera. As the black colour of negroes is sometimes seen beneath their nails, it is probable that the rete mucosum exists there also, but it is not so clearly ascertained, though the observations of M. Gaultier, on the rete mucosum of animals, tend to prove it.f As the nails are entirely destitute of organization, having neither vessels or nerves, they have no power of growth or of disease in themselves, these qualities being deriv cd exclu- sively from the cutis vera. The materials of their formation are accordingly secreted from the cutis vera, in the bottom of * Diseases of Warm Climates. t See rete mucosum. THE NAILS. 309 the groove formed by the latter for the reception of their root. As these materials adhere to the preceding formation, and become concrete; by adding continually to its length, they shove it forward, and thereby elongate it. While this is going on in the groove, the thickness of the nail is also somewhat increased by an excretion from the skin contiguous to its concave surface. This accounts for the nail being thicker in front than behind. Owing to a peculiar morbid state of the proximate surface of the true skin, it sometimes happens, that the contribution to the nail from it exceeds that from the groove, the conse- quence of which is, that the whole nail grows upwards like a horn, instead of forwards. An example of this kind was lately exhibited to me by a scientific friend, Dr. Charles D. Meigs, of this city, in a female aged about ninety. In this case one of the big toe nails had grown upwards, in a semispi- ral manner; to the length of four and a quarter inches, when measured along the outer edge of the spiral. The correspond- ing nail of the other side would have been of nearly the same length, but it had been broken. The nails of all the other toes had assumed a similar manner of growth, and measured from one and a half to two inches. In the case of each nail its anterior extremity presented the primitive nail as it had been before this extraordinary instance of hypertropium. The statement of the patient was, that the growth had com- menced about fifteen years ago. A tendency to this horny growth from the skin, was also manifested in a tubercle, three or four lines long, and with an ulcerated base, from the back of her nose; and also by scaly excrescences on the legs. The patient having died shortly afterwards, the collection of nails was politely presented to the Anatomical Museum, by Dr. Meigs. In cases where the nail has been lost by violence or dis- ease, the cutis vera secretes another; but it differs from the first, unless the cutis vera has been restored to a perfectly healthy action ; from this cause we see, in individuals, thick black nails, sometimes cleft longitudinally. 310 INTEGUMENTS. The nails begin to appear about the fifth month of fcetal life, and are still imperfect at birth. When analysed, they seem to consist in coagulated albumen, with a small quantity of the phosphate of lime. CHAPTER IV. OF THE HAIRS. The Hairs (Pili, Crines) are cylindrical filaments, which are found on most parts of the skin, excepting the palms and the soles. The finest of them are microscopical, and have not a diameter exceeding the one sixth hundredth of an inch. The hairs differ much in their size and appearance in the several parts of the body. Those on the head (capilli, caesa- ries) grow to the greatest length of any, and are most nume- rous in proportion to the space they occupy. Those which surround the mouth, and are on the cheeks, (julus, mystax, barba) exceed the others in size, and when allowed to grow, are next in length, and more disposed to curl. Those around the eyes, (cilia, and the supercilia) are not disposed to exceed an inch in length, and have a long slender conoidal shape. Those at the orifices of the nostrils and ears are of the same habits as the latter. Those of the arm-pit, (glandebalae,) and about the organs of generation, (pubes,) are limited to a growth of a few inches. In the male subject there are hairs of considerable length also on the sternum and about the nipples, an arrangement which seldom occurs in females. In most individuals hairs are found over the whole remaining surface of the body; but in females, and in many males, they are too fine to be readily visible. In some subjects brought into our dissecting rooms, the pilous system has been so developed as to form a shaggy coat over the whole body, and almost to conceal the skin. In the female the hairs of the head are more abundant and THE HAIRS. 311 reach a greater length than they do in the male. As a gene- ral rule the colour of the hairs corresponds w ith that of the eyes and of the skin, and the darker they are the coarser. According to Withoff a quarter of an inch square of skin has upon it 147 black hairs, while the same extent has 162 hazle, or 182 white ones, in other individuals. Each hair consists in a bulb and in a stalk. The bulb is the adherent extremity, and is whiter, softer, and generally larger than any other part; it is received into a follicle, hap- pily compared by Malpighi to the vase containing a flower or plant, and which is deposited most commonly in the sub- cutaneous cellular substance, but sometimes in the skin itself. This follicle is of an oblong ovoidal shape, its open orifice is continuous with the surface of the body, while its internal end is closed and has some filaments passing from it to the adjacent cellular substance. It is formed of two membranes, the external is white, strong, and continuous with the derm or cutis vera; the second being within the last is more soft, delicate, and vascular, and seems to be a continuation of the rete mucosum. From the bottom of the cavity of the follicle, a small conoidal papilla erects itself towards the orifice. This papilla is vascular, and from the dissections of M. Be- clard, on the human subject, and of M. Rudolphi, on the mustachios of seals, is furnished with nerves. The mode of approach of its vessels is not yet settled. M. Gaultier says that the arteries pass from the surface of the skin into the orifice of the follicle, and then descend, in a serpentine man- ner, between its two membranes to the bottom.* M. Be- clard, on the contrary, considers them to pass through the bottom of the follicle. Each piliferous follicle is moreover furnished, within its orifice, with many small sebaceous fol- licles arranged around it. The bulb of the hair has in it a conoidal cavity, open at its base, and receiving the conoidal papilla of the follicle.f The » J. Cloquet, Anat. de l'Homme. PI. CXVIH. fig. II. ■\ GauHier, see Cloquet loc. cit. 312 INTEGUMENTS hair then receives its nourishment from the papilla. The hair is moreover attached to the skin by the cuticle, for the latter having reached the orifice of the follicle is then reflected for some distance along the hair, this increases the strength of the attachment of the hair to the skin. The stalk of a hair has generally the loose extremity smaller than any other part and frequently split. When examined with a microscope the stalk appears to consist of two substances, one within the other. The exterior is a dia- phanous sheath almost colourless, and, from having the pro- perties of the epidermis, may be a continuation of it. The interior consists in from five to ten filaments, parallel with one another, and forming a tube in the centre of the fasci- culus. The tube, as well as the interstices between the fila- ments, is filled with a fluid called the marrow of the hair. This substance corresponds with one of the layers of the rete mucosum of the skin, and contains the colouring matter. The probability is that the whole hair is a continuation of the rete mucosum, to which is joined the envelope of the epi- dermis. The canal in the centre of the hair is said to be unusually distinct in the hog's bristle, it is also well seen in the supercilia; the follicle and bulb are best studied in the mustachios of the larger animals. According to Mr. Heu- singer,* the substance of the hair, when examined with a microscope of strong power, exhibits an areolar appearance. Though the stalk of the hair is destitute of blood vessels and of nerves, yet it is probable from the sudden changes of colour that sometimes occur in it from black to white, owing to terror and grief, that there is a species of interstitial cir- culation going on. The emaciated and peculiar appearance which sickness gives to it, would also tend to support this opinion. Though, strictly speaking, the hairs are devoid of sen- sibility, yet, as the bulb is planted over a sensitive papilla, they communicate certain sensations by being moved or touched. Animals apply their mustachios particularly to this use in * J. Cloquet, loc. cit. THE HAIR. 313 groping through dark places, or when they are deprived of sight. The hairs arc eminently hygroscopic, moisture lengthens and dryness shortens them, this property has caused them to be applied to the construction of hygrometers. In certain animals the hairs are erected by the contraction of the subcutaneous muscle; the movement in the human sub- ject corresponding with that, is the effect of great fright, and is produced by the contraction of the occipito frontalis muscle. In the development of hair, the part which first forms is the follicle, the young hair then pierces it at its summit in the same way that the tooth pierces its capsule. The death of the capsule or the drying up of its fluids occasions the fall of the hair and prevents its regeneration. In old men who are bald there is no appearance of capsule; while in persons from whom the hair has fallen owing to sickness, as the capsules still remain, they soon put forth another crop of hair. The rudiments of the hair are seen about the fifth month of foetal life. The first crop is deciduous, and after covering the body of the foetus like a fine down, till the eighth month of utero gestation, it then falls off; sometimes however it is retained either in whole or in part till after birth, this is particularly the case in regard to the hair of the head. In this deciduous character we see another analogy between the hair and the teeth. When the hair becomes white from age, the conversion of colour begins at the loose extremity, another proof of the in- terstitial circulation or change of particles in it. The same fact is observable in animals who change colour only for the winter. But the restoration of colour begins at the root. It is probable that in those cases of plica polonica attended with bleeding from the root of the hair when it is cut, that the vascular papilla has been so much augmented as to ele- vate itself above the level of the cuticle, and of eourse inter- feres with the sweep of the razor employed in shaving the head. Ignorance in regard to the organization of the hair, and a slight inclination to the marvellous, would magnify vol. i.—R r 314 INTEGUMENTS. this, into every hair in such a disease being a sort of branch pipe from the general circulating system, and therefore bleed- ing upon being wounded. Many of the victims to this dis- ease accordingly prefer the loathsome matting of the hair with which it is accompanied, to the risk of dying by he morrhage. BOOK III. PART Z. CHAPTER I. ON THE GENERAL ANATOMY OF THE MUSCLES* The muscles by their contraction produce the various flexions of the body, and are therefore the organs of motion. They may be known by their redness, softness, irritability, contractility, and by their being formed of long parallel fibres. The redness however does not always attend them, as this colour is very faint in the foetus, and does not exist at all in animals that have not red blood. They form a very considerable share of the whole bulk of the body. Though the most perfect organs of motion, and producing it more efficiently and rapidly than any other apparatus, they are not indispensable to it; for they are not observable in animals of a very low grade, which apparently consist of a sort of cellular or mucous substance. In the next grade of animals, as the worms, where there is a deficiency both of bony and of cartilaginous skeleton, the muscles are percep- tible and produce locomotion by their attachment to the skin or integuments; and finally, in animals which have a skele- • These organs were very imperfectly known to the ancients excepting Galen, and had not generally received names till the time of Sylvius, A. D. 1587. 316 MUSCLES. ton, the muscles are almost exclusively attached to its differ- ent points, and by alternately approximating them effect locomotion. The muscles of the human body are referable to two classes, in consequence of their position and functions, though they present a perfect similitude of structure every where. The most numerous class, as well as that in which the individuals are of the greatest magnitude, are the muscles of voluntary motion : they arc placed between the skeleton and the integu- ments, and constitute the principal bulk of the extremities, and also afford a thick fleshy covering to the trunk. The second class is contained within the large cavities of the skeleton, and form a portion of the structure of the circula- tory, of the digestive, and of the urinary organs; and pro- duce the principal internal motions of the animal economy. Every muscle is surrounded by an envelope of cellular substance called its sheath (Membrana Musculorum Com- munis*) which at different points of the body exhibits vari- ous degrees of condensation. In the muscles of voluntary motion these sheaths are formed by partitions going, from the aponeurotic expansions just beneath the skin, to the perios- teum, and are the prolongations which induced Bichat to consider the periosteum as the centre of the desmoid system. These sheaths in some cases preserve to a considerable ex- tent the ligamentous appearance, but generally cellular sub- stance predominates in them. Upon their existence is founded the great variety of views and descriptions which the later anatomists have taken of the fascia of the human body, some choosing to describe them in one way and some in another. The sheaths of the second class of muscles are composed of a much finer and looser coat of cellular substance than those of the first, and are commonly described as lamina? or tunics to the organs to which they respectively belong. In every case, however, from the internal face of these sheaths a great * Haller, Element. Physiol, torn. i. GENERAL ANATOMY OF THE MUSCLES. 317 many partitions pass off, which penetrate the body or thick- ness of the muscle, to divide and subdivide it into fasciculi, and into fibres, even to their most minute condition. These partitions become thinner the more they are multiplied. The Fasciculi, or Lacerti of muscles, vary very much in*' size, and in their distinctness from each other; in some they are so large and so widely separated as to appear like dis- tinct muscles, such for example as the biceps of the arm and of the thigh, the deltoid, the columnar carnea? of the heart, and several others. But the greater part of the fasciculi are • strictly parallel with each other, and merely separated by a& -. thin lamina of cellular substance. The fasciculi are again*** subdivisible into fibresywhich from their smallness are not* appreciable to the naked eye, and even when examined with powerful microscopes seem to admit of< an endless division. On this account some anatomists have undertaken to classify the fasciculi under the terms of first, second and third orders. It is evident however that this arrangement is too arbitrary to be needful, and that the circumstance is sufficiently ex- pressed by considering the fasciculi as indefinitely divisible. The fibrous arrangement of muscles is rendered still more distinct by boiling them, or by immersing them in alcohol. The structure of the muscular fibre has been studied with great attention by microscopical observers. From such ob- servations it appears that their ultimate shape is prismatic, pentagonal, or hexagonal. According to Prochaska, every fibre extends the whole length of the muscle, considering this length as represented by the tendinous beginning on the one hand, and the tendinous termination on the other. This arrangement holds even in regard to the longest muscles, as the sartorius. The most approved accounts of modern times are those of Mr. Bauer, with Sir Everard Home, and of MM. Prevost and Dumas. These gentlemen concur in stating that the results have been uniform in all the animals to which their observations have been extended. That the muscular fibre is a series of globules, resembling the globules of the blood deprived, of colouring matter and adhering in a 318 MUSCLES. line to each other. That the medium of adhesion is invisible from its transparency and want of colour, but if the muscle be macerated in water frequently changed, that this medium from its greater solubility and more ready putrefaction, may be removed so as to leave the globules detached from each other, and still resembling the globules of the blood. The fact of the globular condition of the muscular fibre was first pointed out by Leuwenhoek and Hook, it is also confirmed by the testimony of Mr. Milne Edwards and M. Dutro- chet. The evidence of their size is very unsettled, it is stated at from one-third to one-seventh of the diameter of a globule of blood, the latter being estimated at one three thousandth of a line, or the 1T65T of an inch. Such minute observations are necessarily very uncertain. In meat which is prepared for the table by roasting or boiling ; or in a muscle which is contracted, one frequently sees the fibres undulated or crooked. By Prochaska it is at- tributed to the bridling of the fibre, by the contraction of its cellular substance, nerves, and blood-vessels. The cause, however, is not well ascertained; the condition seems to be one of the peculiarities of muscular fibre, which it manifests when in a state of contraction only, for it disappears when- ever the fibre is relaxed, either by spontaneous movement, or by stretching it in the dead body. This undulation has pro- bably contributed to the many inexact observations on the structure of muscles. Thus Haller thought that they consisted in a series of ovoid vesicles, which lengthened in a state of relaxation, and became more globular in a state of contrac- tion. It is unnecessary to dwell on mere errors of the eyes or of the imagination, for the fact seems to he now well es- tablished, that, though the muscular fibre, by contracting, loses its straightness and becomes crooked, yet this is effected without change in the form of the globules of which it ulti- mately consists. By some it has been asserted that muscles are only the continuation of blood-vessels. To this it is replied,* that • Bcclard, Anat. Gen. GENERAL ANATOMY OF THE MUSCLES. 319 though insects have muscles, yet they have not blood-vessels, so that the former cannot be a continuation of the latter. Moreover, a successful injection, though it may penetrate very finely between the fibres, so as to cause the muscle to swell considerably, yet none of these vessels can be traced into the ultimate fibre. The vital phenomena and the organ- ization of muscular fibre, are so very different from cellular substance, from nerves, and from vessels, that it cannot be less than a distinct structure. Notwithstanding this limitation which is put upon the dis- tribution of the Blood-vessels, every muscle is abundantly supplied by them. The arteries come from the adjacent large trunks, and penetrate at different points of the periphery of the muscle. They first of all pass between the larger fasciculi and parallel with them; they then divide and follow the course of the smaller fasciculi; they divide and subdivide again after the same rule, till they become mere capillary tubes, from which the nutritive matter is exhaled. The veins accompany the arteries, and receive their blood; some of them creep along the surface of the muscle without having corresponding arteries. Bichat says that they are injected with great facility from their trunks, from which he supposes that their valves are less numerous than in other parts of the system. The colour of the muscular fibre seems to be, in a mea- sure, independent of the blood which circulates in it. Some animals with red blood have white fibres, as frogs. The colour of the muscular fibre is not altered in animals that have been suffocated. The muscular fibres of the intestines and of the bladder, though abounding in blood-vessels, are whiter than the muscles of voluntary motion. Lymphatics have been injected in the intervals between muscles and between their fasciculi. The Nerves of the muscles are large and abundant, as the nerves of the brain and spinal marrow are chiefly spent upon .320 MUSCLES. them. They are generally proportioned to tke size of the muscle which they have to supply, but there is some variety iu this respect. They accompany the arteries, and are united to them by cellular substance. Their ultimate terminations are traced with great difficulty, and there is consequently an uncertainty in this respect. Before they disappear they be- come soft by div esting themselves of their cellular envelope, and are supposed to bring thus their medullary substance in immediate contact with the muscular fibre. The recent ob- servations of MM. Prevost and Dumas, are thought to throw some light on this subject, and have been received with a very respectful attention. They say, that by macerating in clean water, and in a dark place, the muscle of a bullock, and then throwing a strong concentrated light upon it, the distinc- tion of colour between the nerves and the muscular fibres be- comes very apparent. With the aid of a microscope and a fine knife, the nervous ramifications may be thus traced. The trunk of the nerve enters the muscle parallel with its fibres, and soon begins to give off, at right angles, lateral filaments, which penetratebetween the fasciculi and fibres of the muscles, and may be traced to the top of the undulations formed in the muscular fibres. These lateral filaments at some places are two in number, which pass at some distance from each other, but parallel, and terminate by an interchange of fila- ments ; another places the terminating branches are spread out transversely to the muscular fibre, and end by forming loops with themselves. According to this view, the nervous filaments, strictly speaking, have no termination, but run again into the source from which they are derived. The Chemical Analysis of muscles shows them to he com- posed of fibrine, albumen, gelatine, extractive matter; the phosphate^ of soda, ammonia, and of lime; and of the car- bonate of lime. The colour of the muscle may be rendered much Tighter by maceration in clean water often changed. If it be allowed to remain long, it assumes certain appear- ances in its putrefaction peculiar to itself, but occasionally it is converted into a substance resembling spermaceti. .When MUSCULAR MOTION. 321 a muscle is exposed to boiling water, the albumen is raised to the surface like foam; the gelatine coagulates when the muscle is cold; and the fibrine appears as a fibrous grayish substance, insoluble in hot water, closely resembling the fibrine of the blood, and evolving large quantities of nitro- gen by the action of nitric acid. When a muscle is exposed to the fire alone, as in roasting, the albumen is hardened; the gelatine is melted, and runs off in part with the juices of the meat; the extractive matter is that which gives a dark colour to the outside; the fibrine is cooked in the juices of the meat and is then rendered very tender. The muscular parts of animals are amongst the easiest of digestion. CHAPTER II. ON MUSCULAR MOTION The muscles, after death, are soft, easy to tear, and have but little elasticity; it is only during life that they manifest such extraordinary strength, and retain their powers of mo- tion. The general phenomena of the latter have been happily expressed by the word myotility, suggested by M. Chaussier. These phenomena are, contraction, elongation, and, accord- ing to Barthez, a power of remaining motionless or fixed. In contracting, the muscle shortens, swells, and becomes hard; presents wrinkles on its surface; and its fibres are sometimes thrown into a state of oscillation or vibration, from their alternate relaxation and contraction. It is owing to the vibratory motion in the fibres of a muscle, during their contraction, that a rustling is heard on the application of the stethoscope. The hollow, distant rumbling, when the meatus externus is closed by the finger, is owing to the same vibration in the muscles of the finger employed. This is readily proved by the folio wing experiment: close the meatus vol. i.—s s §22 .MUSCLES. with the end of the handle of an awl or fork, pressed against it by the finger, and it will be found that the muscular vibra- tions are continued along the instrument: plant, afterwards, the point of the instrument upon a soft, inelastic substance, so as to make, in that way, the closure of the meatus, and the rumbling will instantly cease. The roaring noise of sea shells may be explained in the same way. The colour re- mains the same, which proves that there is not an apprecia- ble addition to the quantity of its circulating fluids. The rapidity with which this contraction may take place, is ma- nifested in speaking, in running, and in playing upon a stringed instrument, and its strength, by the immense bur- dens that some individuals can raise and bear. The power of elongation or relaxation seems to be an active state of the muscle, as well as its contraction. The fixed- ness of muscles which are contracted spasmodically, and their retaining this position even after death, until putrefaction begins to assail them, show that the power of elongation does not depend simply upon elasticity; for the latter quality being as much the attribute of dead as of living matter, would be brought into play on death. This power of relaxation or of elongation is much inferior to that of contraction; it seems to be only what is sufficient to restore the muscle to its pro- per length, so as to put it in a condition for the renewal of its contractions. The fixation of muscles is not a distinct power, but merely a qualification of contraction, by which the latter may be ^arrested at any given point, and retained there. As every muscle augments in thickness during its contrac tion, physiologists have earnestly inquired whether the whole mass of muscle was increased or diminished by its contrac- tion. Swammerdam, in order to ascertain it, put an insulated solid muscle, not yet dead, into a tube filled with water; by irritating the muscle, and causing it to contract, the water descended : but this result was not uniform. When an arm is plunged into a tube properly formed and filled with waj;er, if the muscles be caused to contract the fluid descends ; but »he objection to the inference from this experiment is, thai MUSCULAR MOTION. 323 when all the muscles of the arm are caused to contract vio- lently, the introduction of arterial blood is much arrested, if not fully stopped ; and the venous blood is at the same time expelled ; so that the change in the size of the member may be accounted for in that way. The experiments of Erman on eels, fully immersed in a fluid, and submitted to galvanic in- fluence, are said to substantiate the theory of the muscles diminishing in bulk by contracting.* The activity of a muscle, though closely depending upon the afflux of blood to it, is not entirely so, for it is ascertained that galvanism will cause the muscles of frogs to contract, when the circulation is arrested by death, or when the blood is coagulated, or even when it has been drawn off.f This phenomenon, however, can only last a comparatively short time, for a muscle soon dies, and runs into a state of morti- fication, after its vascular and nervous communications have been cut off. Physiologists have entertained very different opinions on the causes of the muscles contracting, or on mus- cular irritability as it is called. Some have supposed it to be an attribute of the muscle itself ;\ others that it depended on the blood vessels, which, by bringing a greater afflux of fluids into its interior, between its fasciculi and fibres, obliged the two latter to take a more flexuous course; and others, on the nerves.§ Any decision on this point is inconclusive, because it is well known that perfect muscular action requires a healthy state of the muscle, and an uninterrupted nervous and sanguineous influence, so that it seems to be a result from the combination of three systems, more than an attri- bute of one alone. || MM. Dumas and Prevost say, that in consequence of the final nervous ramifications crossing the muscular fibres at * Beclard, loc. cit. + Frochaska de Came Musculari. Vienne, 1778. * Haller, Physiol. § Legallois sur le principe de la vie. || Meckel, Anat. Gen. from Barzellotti. Esame di alcuni modeme teone interno alia causa prossima della contrazione moscolare. 1796, 324 MUSCLES. right angles to them, and parallel with one another, the gal- vanic current which passes through these ramifications, causes the latter to approach each other reciprocally, whereby the muscular fibres to which the ramifications are fixed, are thrown into wrinkles. It is clear from this theory, that the muscu- lar fibres themselves are destitute of the power of contraction, and that they are only the frame work upon which the gal* vanic batteries of the nervous system are displayed. There is no muscle which has not the power of contracting some time after apparent death, and this phenomenon fre- quently continues for an hour ; it is uncommon for it to cease with the apparent extinction of life. This irritability is of different durations in the different muscles ; it is first lost in the left ventricle of the heart; then in the large intestines % afterwards in the small and in the stomach ; then in the bladder ; then in the right ventricle, the iris; and in the volun- tary muscles, of which those of the trunk die first, those of the inferior extremities next, and those of the superior last. The last act of life is in the auricles, of which the right pul- sates longest. Different circumstances may produce some variety of this progress in the loss of muscular irritability, but it will be found generally correct.* The experiments of Himlyf demonstrate, that laurel water, or that of bitter almonds, applied to the stomach or brain, renders the heart insensible to the strongest stimulants, while the muscles of volition continue to move for some hours afterwards. The duration of irritability is, however,, much varied, according to the nature of .the death, and the state of health preceding. Nysten asserts, that he has seen the right auricle of a robust man pulsate nine hours after death. In death from chronic diseases, with much emaciation, the heart ceases to beat shortly after intellectual phenomena cease. And in death from electricity ; from a blow upon the stomach ; from the in- halation of carhuretted hydrogen gas, and some other poison- ous ones, muscular contraction ceases universally in a few moments, and cannot be excited by any artificial means. * Meckel, Anat. Gen. f Commentatio de Morte, Goettingue, 1794, MUSCULAH MOTION. 325 The Irritability of the muscles is so modified that cer- tain stimulants are peculiarly appropriate to one and not to another. For example, light is the specific stimulant to the iris; a mechanical application to it as in making arti- ficial pupil, is borne frequently fwithout its contracting. The heart is very sensible to mechanical stimulants, and ad- ditionally so when they are applied to its internal surface. Some of the muscles are regularly under the influence of the will, others not at all so, which has given rise to their divi- sion into voluntary and involuntary. These states, though kept perfectly distinct from each other in health, are some- times blended in disease, the voluntary muscles becoming involuntary in their actions ; and the involuntary voluntary, which, however, is much more uncommon than the other. i The voluntary muscles arc generally such as serve for lo- comotion and speech, and receive their nerves directly from the spinal marrow. The involuntary muscles are such as are concerned in the functions of digestion, respiration, and circulation, and which, in order to continue the life of the ani- mal, must never cease their actions for any long interval. It is worthy of remark, that apoplexy and other cerebral affec- tions, paralyze most commonly the voluntary muscles alone, while the others retain their usual state and sensibilities. When irritability is entirely gohe from a muscle, and it is actually dead, the whole muscular system becomes stiff, beginning with the trunk, then the superior, and lastly the inferior extremities. This condition seems to be indepen- dent of the nervous system, as the destruction of the spinal marrowT, the cutting of nerves, and hemiphlegia do not arrest it. It is thought, by M. Beclard, to be analogous to the contraction of the fibrine of the blood, and, like the latter, does not cease till putrefaction begins. The degree, as well as the time, of its access is variable under different circum- stances. In very aged persons; in suclj as have died from protracted disease attended with great emaciation; in scor- butic and gangrenous diseases; the stiffness comes on quick- ly, is very slight, and disappears in a couple of hours. But in muscular subjects who have died from sudden violence or 526 MlSCLEi from acute diseases, the stiffness is sometimes postponed for twelve hours or more, and may continue, in the winter, from three or four days to a week or even longer, depending upon the access of putrefaction. The sensibility of the muscles is moderate. When they have been much exercised they only give out the sensation of fatigue. In amputations the pain of cutting through them is not equal to that of the skin. In inflammations they, as most other parts, have their sensibility exalted to an exqui- site degree. The muscular system of the embryo is first of all in a ge- latinous state, and confounded with cellular substance ; but at two months from conception, the fibres are distinct, and at four they begin to contract and to execute different motions. The muscular system is subject to varieties of conforma- tion. Robust, muscular individuals frequently have super- numerary heads to their muscles, particularly in the extremi- ties. In monstrous foetuses it sometimes happens that the muscular system is either wholly or partially supplied by adipose matter and by infiltrated cellular substance. CHAPTER III. ON THE MECHANICAL SHAPE AND ARRANGEMENT OF THE VOLUNTARY MUSCLES. Evert muscle consists in a belly and in two extremities, of which the one that is the fixed point is the head or origin, and the other is the tail or insertion. The belly or body is the fleshy part, the extremities are generally tendinous, either completely or partially. Some of the muscles arise by a single head and are insert- ed into one point. Some few arise by a plurality of heads OF THE TENDONS. 327 but have a single insertion, as the biceps flexor of the arm, and of the thigh; others again have a single head but a plural insertion, as the flexors of the fingers and of the toes; others again have multiplicate heads and multiplicate insertions, as the muscles of the back. The most simple muscles are such as have their fibres running in the direction of the length of the muscles, of which there are many examples, as the sartorius, the biceps flexor cubiti, the semitendinosus, and others. Others again have their fibres running obliquely from a tendon or a bony origin on one side of the muscle, to a tendon on the other, as the semimembranosus, the peronei, &c. these are called musculi semi pennati. Others have a long tendon in the centre to which the fibres converge obliquely, forming an angle with each other, they are the penniform (musculi pennati.) Others again are formed of a congeries of smaller muscles, the fibres of which run in different directions and are intermixed with tendinous matter, as the deltoid and the subscapular. As the strength of a muscle depends upon the number of its fibres, those whose fibres go obliquely are stronger than if their fibres had run longitudinally. CHAPTER IV. OF THE TENDONS. The tendinous extremities of muscles, present themselves under two general shapes, one is funicular, or like cords, varying in shape from cylindrical to paraboloid $ the other is spread out into a membrane, and resembles an aponeurosis. They both adhere with great tenacity to the muscular fibres, so as to have induced, erroneously, the opinion of absolute continuity : but maceration and boiling will separate them, 3^8 MUSCLES. and the course of the fibres is different even to the naked eye; besides the very obvious difference in colour, in con- sistence, and in vital properties. The tendons are surrounded by a loose cellular membrane or capsule, which permits them to glide freely upon each other : in some places this membrane is wanting, and there, it is supplied by a synovial membrane answering the same purposes. The tendons are readily recognized by their white and shining appearance ; they have no elasticity or power of elon- gation and contraction, and therefore like other ligamentous matter, they are lacerated sooner than they can be stretched. They are composed of desmoid tissue, the fibres of which are united by a compact cellular substance in small quanti- ties. The fibres are longitudinal, and may be readily sepa- rated either by maceration or by a slight boiling. When a round tendon is prepared in this way, it is easy to flatten it out into an aponeurotic membrane : the fibres are then made very distinct, and seem to adhere to each other by lateral fibrillar. In ordinary health no red blood penetrates into the tendons, but if they become inflamed, as their capil- laries then enlarge, they admit the red globules; at the same time their sensibility from being entirely organic, or what is only sufficient for the internal actions of the organ, is so much augmented as to be very manifest.* The tendons have the character at large of the desmoid tissue,! but are • A knowledge of this disposition in tendons to augment their powers of circulation on being inflamed, together with Dr Physick's great success in the treatment of unnatural joints by a seton passed through the cavity of the fracture, induced me in alate tourof service at the alms house to try the effect of a similar plan upon a ruptured tendo achillis, which from the long period since the accident happened did not promise a cure on the ordinary princi- ples of treatment. A seton of silk ribbon was accordingly introduced, and kept in its place for six weeks and a half. It produced considerable pain, tumefaction, and inflammation, but has been followed by an apparently per- fect reunion of the ruptured ends of the tendon.—Chapman's Med. and Phya. Journal, for July, 1826. t See page 34. OF THE TENDONS. 329 more gelatinous, or completely soluble in boiling water, than the ligaments. They have a great affinity for the phosphate of lime, and hence we frequently find them hardened and having small pieces of bone in them, where they run over bony trochlea. vol. i.—t t BOOK III. PART XX. Special Anatomy of the Muscles.* CHAPTER I. MUSCLES OF THE TRUNK. SECT. I.—MUSCLES ON THE POSTERIOR FACE OE THE TRUNK, The Trapezius, Is a beautiful broad muscle, immediately under the skin, covering the back parts of the neck and thorax, and extend- ing from the bottom of the latter to the top of the former. Its * I may here mention, once for all, in regard to the muscular system, that though the very rigid mode of description adopted by anatomists may lead the inexpetienced student to infer that there are no departures from a com- mon standard, and that one invariable type for the muscles prevails in all hu- man beings; yet there will be found upon actual dissection occasional disagree- ments with the best established descriptions, and which it is of some use to know. Some of these departures are common enough, others very rare; and they consist either in a deficiency or a redundancy of muscles. Wishing not to give false ideas of their importance and frequency, and indeed fearful of doing so; they are purposely introduced subordinately in notes: many of them have been observed by me personally, others are recorded in dif- ferent medical writings, and for the remainder I am indebted to the leamejj treatises on anatomy of T. Soemmering and J. F. Meckel. MUSCLES OF THE TRUNK. 3S1 anterior edge above, is parallel with the posterior edge of the sterno cleido mastoideus. Its posterior edge is joined with that of its fellow, and below, it overlaps in part the la- tissimus dorsi. It arises from the occipital protuberance, and from eight or ten lines, sometimes more, of the upper transverse ridge of the occiput, by a tendinous membrane. It arises also from the five superior spinous processes of the neck, through the intervention of the Ligamentum Nuchse, and tendinous from the two lower spinous processes of the neck, and from all of the back. It is inserted fleshy into the external third of the clavicle; tendinous and fleshy into the acromion process, and into all the spine of the scapula. Its fibres having a very extended origin, mnst of course converge in getting to these insertions; the upper fibres descend, the lower ascend, and the middle are horizontal. It draws the scapula towards the spine. In the cervical portion of these muscles, formed hy the origins of both mus- cles united, is an elliptical expanse of tendon, lying over the ligamentum nuchse, and extended on each side. The liga- mentum nuchas itself, as mentioned elsewhere, is a vertical septum of ligamentous matter, departing from the central line of the occipital bone, to the spinous processes of all the vertebra of the neck. At its upper part, where the spinous processes of the neck are short, this septum is very broad, and divides completely the muscles of the two sides of the neck from each other.* Tke Latissimus Dorsi, Is situated under the skin at the lower part of the back, so as to cover its whole posterior portion. It arises by a thin, • Varieties. It is sometimes short of the origin described, by from one to ibur, of the lower spinous processes of the back. Also, the lower fasciculus is sometimes disjoined from the rest of the muscle, by a large triangular •spaoe. $32 MUSCLES. tendinous expanse, from the seven inferior spinous processes of the back ; and by a thick tendinous membrane from all the spines of the loins and sacrum. This membrane is the fascia lumborum ; is common to several of the muscles which have their origin in this region ; and extends along the iliac mar- gin of the sacrum, so as to arise also from the posterior third of the spine of the ilium.* Besides these origins, the latis- simus dorsi has from the sides of the four inferior false ribs, four fleshy heads which are interlocked with the inferior heads of the obliquus externus abdominis. From this extended origin the fibres converge, so as to form the posterior fold of the axilla ; and to terminate in a flat, thick tendon, of two inches in breadth, which is inserted into the posterior ridge of the bicipital groove of the os hu- meri. The upper part of this muscle passes over the inferior angle of the scapula, and derives a fasciculus of fibres from it. It is there behind the teres major, but as it advances winds around the inferior edge of the latter so as to get be- fore it. Afterwards the tendons of the two adhere closely, but have a bursa between them at their termination. That portion of the tendon of the latissimus which is continuous with the lower edge of its fleshy belly, by a half spiral turn in the latter, becomes uppermost, while the upper portion is by the same arrangement made lowest. At the place of its insertion, it is commonly glued to the pectoralis major. The inferior margin of its tendon, detaches a slip to the brachial fascia, and the superior margin another to the little tube- rosity of the os humeri. It draws the os humeri downwards and backwards.f * This origin frequently is tendinous at the back part of the ilium, and fleshy in front. f Varieties. Sometimes from its anterior extremity a fleshy or tendinous slip is detached in front of the coraco brachialis, and is inserted into the posterior face of the tendon of the pectoralis major. The brachial vessels and nerves are liable to compression from this arrangement, which is said to be natural to birds and moles. Another variety is where a slip runs from this muscle, adheres to the coraco brachialis and is inserted tendinous into the coracoid process of the scapula. MUSCLES OF THE TRUNK. 333 The Serratus Inferior Posticus. The origin of this muscle is inseparably united to that of the latissimus dorsi by a tendinous membrane (fascia lumbo- rum) and comes from the two inferior spines of the back, and the three superior of the loins. It is inserted by fleshy digitations into the under edge of the four inferior ribs. It draws the ribs downwards, and is an antagonist to the diaphragm in some respects, but more particularly to the serratus superior posticus. The removal of the trapezius brings into view several muscles; the most superficial of which are the rhomboid, there being two together looking very much like one. The Rhomboideus Minor, Is above the other. It is a narrow muscle which arises by a thin tendon from the three inferior spines of the neck, and passing obliquely downwards is inserted into the base of the scapula opposite the beginning of its spine. The Rhomboideus Major. Arises also by a thin tendon from the last spine of the neck, and from the four superior of the back, and is inserted into all the base of the scapula below its spine. These muscles draw the scapula upwards and backwards. The Serratus Superior Posticus, Arises by a thin tendon from the three inferior spines of the neck, and the two superior of the back, and is inserted into the second, third, fourth, and fifth ribs, by tendinous and fleshy slips, a little beyond their angles. This muscle draws the ribs upwards. 334 MUSCLES. Between the two serrati is an aponeurotic expansion de- scribed by Rosenmuller, which connects them with each other, and has induced some anatomists to consider them as but one muscle. It is thin and diaphanous, but has the fibrous structure very apparent, and running in a transverse direction from the spinous processes to the angles of the ribs. The superior margin of the latissimus dorsi also runs into this fascia, so as to render its own bounds somewhat unde- fined. This fascia, along with the ribs and vertebra, forms that canal in which are contained the deep seated muscles of the back. The Levator Scapulae, Is placed between the posterior edge of the sterno-cleido- mastoideus and the anterior of the trapezius ; its lower end is just above the rhomboideus minor. It arises by rounded tendons from the three, four, or five, superior transverse pro- cesses of the neck, between the scaleni muscles and the sple- nius colli. It is inserted fleshy into that part of the base of the scapula above the origin of its spine. As its name expresses, it draws the scapula upwards. A good view of this muscle may be obtained in the front dissection of the neck.* The Splenius, Has its inferior extremity beneath the serratus superior posticus, but the principal part of it is covered by the trape- zius. It arises from the spinous processes of the five inferior cervical, and of the four superior dorsal vertebra. It is inserted into the back of the mastoid process and into a small part of the adjacent portion of the os occipitis, also into the transverse processes of the two superior cervical ver- * Varieties. Sometimes it arises from only two superior transverse pro- cesses ; occasionally its fasciculi are separated from the neck to the scapula; or, a long one is detached towards the spine, thereby presenting a similar disposition with what is met with in the dolphin. MUSCLES OF THE TRUNK- 3S5 tebrae. It is customary to consider the part which goes to the head as Splenius Capitis, and the part below as Splenius Colli; the latter, in that case, is said to arise from the third and fourth dorsal vertebrae. It draws the head and neck backwards. Between the spinous processes of the vertebrae and the an- gles of the ribs, on either side, the deep fossa is filled up en- tirely by muscles. Some of them are large and powerful, and the most striking are the Sacro Lumbalis and the Longissi- mus Dorsi. The Sacro Lumbalis and Longissimus Dorsi, Have a common origin from the back of the pelvis and of the lumbar vertebrae, and extend to the top of the thorax. They arise, tendinous externally, and fleshy internally, from the posterior surface of the sacrum by its external margin and spinous processes; they arise also, tendinous, from the spinous processes, and fleshy, from the ends of the transverse processes of all the vertebrae of the loins; and principally tendinous from the posterior part of the spine of the ilium. The external margin of this belly is fleshy, but all the part nearest to the spine is wholly tendinous below, and only so on the surface, higher up. The tendon is very strong and divided into fasciculi, chiefly, near the spinous processes of the lumbar vertebrae. From the under surface of this com- mon belly, two tendinous and fleshy heads are inserted into the inferior edge of the transverse process of each lumbar vertebra, the smaller near its root, and the larger near its' extremity. On a level with the lowest rib, and, indeed, somewhat below it, a fissure occurs in the muscle which di- vides it into the two parts. The Longissimus Dorsi is nearest the spine; it is inserted, by small double tendons proceeding from its internal surface, into the ends of the transverse processes of all the vertebrae of the back, except the first. It also, from its outer edge, sends long slender tendons, by which it is inserted into the 336 MUSCLES. under edges of all the ribs near their angles, except the two inferior. The Sacro Lumbalis is inserted from its outer edge into all the ribs at their angles, by long and thin tendons, which are successively longer, the higher they are inserted. By turning over this muscle from the other, towards the ribs, one may see coming from the eight lower ribs, as many slips, which run into the under surface of the sacro lumbalis; they are the Musculi Accessorii ad Sacro Lumbalem. These two muscles keep the spine erect, and draw down the ribs.* Between the ends of the spinous processes and the edge of the longissimus dorsi, is a muscle almost entirely tendinous, and scarcely to be distinguished from the latter, both in con- sequence of its close connexion with it, and of its insignifi- cant size. At its lower part, it is absolutely a portion of the Longissimus, and can be separated from it only by an unna- tural division. It is a mere string lying along the sides of the spinous processes, and is called from its origin and inser- tion, the Spinalis Dorsi. The Spinalis Dorsi, Arises tendinous from the spinous processes of the two su- perior lumbar, and of the three inferior dorsal vertebrae, and is inserted tendinous into the spinous processes of the nine superior dorsal vertebrae, except the first. It tends to keep the spine erect. The Cervicalis Descendens, Is a small muscle placed at the upper portion of the tho- * Varieties. The origin is uniform, but the insertions vary in their num ber. Sometimes, a fasciculus commences by a tendinous beginning from the fourth rib, and is inserted into the transverse process of the sixth verte- bra of the neck; a fasciculus from the sacro lumbalis joins the fascia extended between the two serrati, or reaches to the splenius colli; the two muscle? are sometimes joined closely by an intermediate fasciculus. MUSCLES OF THE TRUNK. 337 rax, between the insertions of the sacro lumbalis, and of the longissimus dorsi into the upper ribs ; it looks, at first, very much like a continuation or appendix of the first, running to the cervical vertebrae. This muscle arises from the upper edges of the four supe- rior ribs by long tendons; it forms a small belly, which is inserted by three distinct tendons into the transverse pro- cesses of the fourth, fifth, and sixth vertebrae of the neck, be. tween the levator scapulae and splenius colli. It draws the neck backwards. ~ The Transversalis Cervicis, Is on the inner side of the last, and in contact with it, be- ing about the same size, and having very much the same course and appearance. It is considered as an appendage to the longissimus dorsi. It arises from the transverse processes of the five superior dorsal vertebrae by distinct tendons, and forms a narrow fleshy belly, which is inserted by distinct tendons also, into tiie transverse processes of the five middle cervical vertebrae. It draws the head backwards. The Trachelo Mastoideus, Is at the inner side of the last muscle, in contact with it. It arises by distinct tendinous heads, from the transverse processes of the three superior vertebrae of the back, and of the five inferior of the neck; and is inserted, by a thin ten- don, into the posterior edge of the mastoid process. The dorsal origins are frequently deficient or irregular. It draws the head backwards. The Complexus, A fine large muscle, is situated at the inner face of the trachelo mastoideus, and is readily recognized in showing itself between the bellies of the two splenii capitis, just below vol. i.— uu 338 MUSCLES. the occiput. A quantity of tendinous matter exists in its middle, which gives it the complicated appearance from whence its name is derived. It arises, by tendinous heads, from the seven superior dorsal, and the four inferior cervical vertebrae, by their trans- verse processes; also, by a fleshy slip from the spinous pro- cess of the first dorsal. It is inserted into the inferior part of the os occipitis, on the surface between the upper and lower transverse ridges, and on the outside of the vertical ridge which exists in the middle of the bone. It draws the head backwards. The Semispinalis Colli, Is a muscle which passes obliquely from transverse to spi- nous processes, and is situated between the complexus and the multifidus spinae ; the course of its fibres renders it diffi- cult to be distinguished from the latter. It arises from the transverse processes of the six upper vertebrae of the back, by tendons which are involved with those of the adjacent muscles ; and passes up to the neck, to be inserted into the sides of the spinous processes of the five middle cervical vertebrae. It extends the neck obliquely backwards. The Semispinalis Dorsi, Is lower down on the spine, and with difficulty distinguish- ed from the multifidus; like the last it passes from trans- verse to spinous processes. It lies under the longissimus dorsi, between it and the multifidus. This muscle arises by tendons connected with those of the other muscles, from the transverse processes of the seventh, eighth, ninth, and tenth dorsal vertebrae; and passes upwards obliquely, to be inserted, tendinous, into the sides of the spi- nous processes of the two lower cervical, and of the five upper dorsal vertebras. It draws the spine obliquely backwards. MUSCLES OF THE TRUNK. 339 The Multifidus Spinse, Lies under the muscles as yet mentioned, close to the bones of the spine; in order to see it well, they, therefore, should all be cut away. It has its commencement, tendinous and fleshy, on the back of the sacrum, being connected to its spinous processes and posterior surface, also to the back part of the spine of the ilium. It there forms a belly of sufficient magnitude, to fill up much of the cavity between the spines of the sacrum and the posterior part of the ilium. It arises also from the roots of the oblique and transverse processes of all the ver- tebrae of the loins, of the back, and of the four inferior of the neck. The multifidus is inserted, tendinous and fleshy, into the roots and sides of the spinous processes of all the vertehrse of the loins, of the back, and of the five inferior of the neck. This muscle consists of a great number of small bellies, which are parallel to each other, arise from a transverse process, and go to the spinous process either of the first or second vertebra above it. It twists the spine backwards and keeps it erect Between the head and the first and second vertebrae, and between the two latter, there are on either side, four small muscles, intended for the motion of these parts upon each other. They are brought into view by the removal of the complexus. The Rectus Capitis Posticus Major, Arises tendinous and fleshy, from the extremity of the spi- nous process of the dentata, and is inserted into the inferior transverse ridge of the os occipitis, and part of the surface below it. Its shape is pyramidal, the apex being below. It turns the head, and also draws it backwards. U9 MUSCLES. The Rectus Capitis Posticus Minor, Is at the internal edge of the first It arises tendinous from the tubercle on the back part of the first vertebra, and is inserted into the internal end of the inferior transverse ridge of the os occipitis, and into part of the surface between it and the foramen magnum. It is also pyramidal, with the apex downwards. It draws the head backwards. The Obliquu? Capitis Superior, Arises from the transverse process of the first cervical vertebra, and is inserted into the inferior transverse ridge of the os occipitis, behind the posterior part of the mastoid pro- cess, and beneath the complexus muscle. It draws the head backwards. The Obliquus Capitis Inferior, Arises from the side of the spinous process of the dentata, and is inserted into the back part of the transverse process of the first vertebra of the neck. It rotates the first vertebra on the second. The Interspinales, Are small short muscles, placed between the spinous pro- cesses of contiguous vertebrae. In the neck they are double, in consequence of its spinous processes being bifurcated ; in the back they are almost entirely tendinous; in the loins they are single and well marked. They draw the spinous processes together, and keep the spine erect. The Intertransversarii, Are also short muscles placed in a similar manner, between MUSCLES OF THE ABDOMEN. 341 the transverse processes of the vertebrae. In the neck they are double, in the back they are small, tendinous, and not well marked ; and in the loins they are single and well seen. They draw the transverse processes together, and will, of course, bend the spine to one side. \ The Levatores Costarum, Are small muscles concealed by the sacro lumbalis and longissimus dorsi, and pass from the transverse process of the last cervical and of the eleven superior dorsal vertebrae, to the upper edges of all the ribs. They are twelve on either side of the spine, are tendinous in their origins and inser- tions, with intermediate muscular bellies. The upper ones are small and thin, and they increase in magnitude as they descend. From the inferior edge of nearly all these muscles a fleshy slip is detached, which passes over the rib next below its origin, to the second rib below, and occasionally to the third. These slips are called Levatores Costarum Longiores. The others which descend from the transverse process to the rib next below, are called Leva- tores Costarum Breviores. These muscles are parallel in their obliquity, with the ex- ternal intercostals, and are not very obviously separated from them. They perform the same service, that of elevating the ribs.* SECT. II.—MUSCLES AND FASCIA OF THE ABDOMEN. Between the most superficial of the abdominal muscles^ which is the external oblique, and the skin, is found the Fascia Superficialis Abdominis. In lean subjects it is very * No part of the muscular system varies more in different subjects than the muscles of the back; but as it would be useless to enter fully on such trivial details, they have been passed by, except in a few instances. 342 MUSCLES. distinct, but in fat ones not so much so, from being blended with adipose matter. The laminae of it which are next to the muscles, are kept, in the latter case, rather more free from fat than the more superficial. It consists of condensed cellu- lar substance, with very little fibrous matter in it, and may be considered as taking its origin on the front of the thigh, and extending in front of the abdominal muscles, as high up as the thorax; indeed, if wTe are disposed to trace it to its whole extent, there is no difficulty in following it over the front of the thorax, also to the neck, and even to the face. In ordinary cases its desmoid or aponeurotic character is very equivocal, but where the parts about the groin have been pressed up6n and thickened by the irritation of hernial pro- trusion it is better marked. On the thigh it is more blended with fat and encloses between its laminae the lymphatic glands of the groin, and the external pudic vessels given off from the femoral artery, immediately below Poupart's liga- ment. On the tendon of the external oblique it is more con- densed ; branches of the femoral artery are also seen in it there, one longer and larger than the others ; the arteria ad cutem abdominis of Haller, winds over Poupart's ligament, and runs upwards somewhat in the line of the epigastric ar- tery, to be distributed to the skin of the abdomen ; the divi- sion of it will produce sufficient hemorrhage to require atten- tion. On the symphysis pubis and about the external ring the laminae of the fascia superficialis are multiplied, and it has more of the character of common adipose matter, as in all cases the adeps there is abundant. From the pubes it may be traced as a condensed cellular membrane along the penis to its extremity, and, according to Mr. Colles of Dub- lin, when matter is formed beneath it, it is apt to create fis- tulous sores on this organ. A thin edge of this membrane may be tracedfor some distance reflected along the sperma- tic cord. This fascia is more loosely connected to the parts beneath-**, along the anterior margin of Poupart's ligament, than elsewhere, which disposes femoral hernia to observe that course in its increase. MUSCLES OF THE ABDOMEN. 343 The Fascia Superficialis, under the name of Tunica Ab- dominalis, is well developed in animals with a large and pro- jecting belly, particularly in the large ruminantia and the solipedia. It has a yellowish tinge in them, is very elastic and strong, and well calculated to support their viscera.* There are five pairs of muscles called abdominal; to wit, the External Oblique; the Internal Oblique; the Trans- verse; the Straight; and the Pyramidal. The three first are flat, and lie in layers one upon the other; the other two are long. 1. The Musculus Obliquus Externus, Arises from the eight inferior ribs by muscular and tendi- nous digitations attached near their anterior extremities. The first head is covered by a slip from the pectoralis major, the five upper heads are interlocked with the serratus major anticus, and the three inferior with the latisshnus dorsi. The fibres pass obliquely downwards, and terminate in a broad thin tendon. This tendon extends over the whole front of the abdomen, from the lower end of the second bone of the sternum to the symphysis of the pubes. It is inserted into the whole length of the linea alba ;• into the anterior half or two-thirds of crista of the ilium, by muscular fibres posteriorly, and tendinous anteriorly; and, from the anterior superior spinous process, the tendon extends to the body, and to the symphysis of the pubes, forming thereby the ligament of Pouparfr. In the middle line of the body, the tendons of the three broad muscles, on both sides of the abdomen, unite to form the Linea Alba, which extends from the sternum to the pubes. From two to three inches in the adult, on either side of the linea alba, but more distant from it above than below, is another line, formed by the same tendons, which is the Linea * Breschet, Thefeis Sur L'Hernie. Paris, 1819. 344 MUSCLES Semilunaris. The navel, which 'originally was a hole for the passage of the umbilical vessels, and, in the adult, is commonly depressed into a pit, now appears in the linea alba as a protuberance composed of condensed cellular membrane. Just at the navel there is a line crossing the linea alba, and extending from one linea semilunaris to the other; at the lower end of the Cartilago Ensiformis, there is another; and half-way between this and the navel, a third : about half-way between the navel and the pubes is a fourth, but it is generally imperfect. These are the Lineae Transversae, and they are formed by tendinous matter in the substance of the recti muscles, connecting them to their tendinous sheath iu front. The most interesting insertion of the tendon of the exter- nal oblique, is the portion constituting Poupart's Ligament The latter, as it approaches the pubes from the ilium, splits so as to leave a hole for the passage of the Spermatic Chord in the male, and of the Round Ligament of the Uterus in the female. This opening obtains the name of the Abdominal Ring. The tendon forming its upper boundary is inserted into the symphysis pubis, and into the pubes of the opposite side, by fibres which are interwoven with, and decussate those of its fellow. The tendon forming the lower margin of the ring is inserted into the spine of the pubes, and into its crista for an inch. The portion inserted into the crest of the pubes is Gimbernafs ligament, which, it will be readily understood, means only a part of Poupart's. The ring in the External Oblique is rather triangular than round; its base is formed by the body of the pubes, and its point is at the place where the tendon splits. The latter is kept from parting still further by a fasciculus of tendi- nous fibres, which runs across it. The sides of this opening are called its Columns, and from their situation, internal and external, or upper and lower Columns. In the female it is oval and scarcely half an inch long. There are several small round holes in the tendon of this muscle, which afford passage to nerves and to veins. When, MUSCLES OF THE ABDOMEN. 345 by the cleanness of the dissection, the tendon has its charac- teristic gloss and polish, they are very distinct. Use. This muscle compresses the viscera of the abdomen, and brings the pelvis and thorax towards each other.* 2. The Obliquus Internus, Lies beneath the last, and its fibres pass in a contrary di- rection to the fibres of the other. It arises tendinous, bv the fascia lumborum, from the three inferior spinous processes of the loins, and from all those of the sacrum ; tendinous and fleshy, from the whole length of the crista of the ilium ; and fleshy from the upper half of Poupart's ligament. Though the fibres of this muscle, in general, decussate the fibres of the external oblique, all of them do not; for the lower are brought gradually to pursue the same direction towards the symphysis of the pubes. Near the Linea Semilunaris, the muscular fibres cease, and the tendon begins. It is inserted into the cartilaginous margin, formed by the six inferior ribs: that is, by tendon resembling condensed cellular membrane, into the cartilages of the seventh, eighth, and ninth ribs; and by flesh into the tenth, eleventh, and twelfth. It is inserted also into the side of the ensiform car- tilage, its whole length ; and into the linea alba, from the sternum to the pubes. The tendon of this muscle divides into two lamina, which enclose the rectus muscle, and thereby form a sheath for it, imperfect however at the lower posterior part near the pubes. * Varieties. Sometimes a considerable part of its middle and anterior portion is deficient, a vitiated conformation to which it is subjected along with the other abdominal muscles. The inferior part of its tendon is incom- pletely developed by the absence of the superficial fibres which retain to- gether the more deeply seated, by which it is weakened and caused to gape by one or more large oblong fissures; this variety gives occasion to a form of inguinal hernia, differing materially from what is common. VOL. I---X X 546 MUSCLES. Its use is the same as that of the External Oblique.* S. The Transversalis Abdominis, Arises by the Fascia Lumborum, from the transverse pro cesses of the last dorsal, of the four upper lumbar vertebrae, and from the back part of the spine of the ilium. It also arises, fleshy from the anterior two-thirds of the spine of the ilium, and from the exterior half of Poupart's ligament; ten- dinous and fleshy alternately, from the inferior margin of the thorax formed by the cartilages of the six or seven infe- rior ribs, at their inner surfaces, where they are concerned in the origin of the diaphragm. The fleshy part of this muscle occupies about one-third of its extent. It is inserted, into the side of the ensiform car- tilage, filling up the vacancy between it and the cartilages of the sixth and seventh ribs; and into the linea alba, from the extremity of the sternum to the pubes. The Transver- salis and the Internal Oblique also form below, a common tendon, which is inserted-for an inch, into the crista of the pubes behind the insertion of Gimbernat's Ligament; into the spine of the pubes ; and into that part of the body of the pubes which forms the lower posterior boundary of the ex- ternal abdominal ring. Just above this insertion the com- ihon tendon alluded to, splits into two laminae, one going before and the other behind the pyramidalis muscle, so that a sheath is thus formed for it. Use; to compress the contents of the abdomen.! 4. The Rectus Abdominis, Is seen beneath the tendons of the other muscles on either side of the linea alba. Its origin is by a flat tendon of an * Varieties. It is sometime* defective at its lower part, and on other oc- casions redundant. f Varieties. Sometimes transverse tendinous fibres creep across its belly; and on other occasions a smaller transverse muscle is present which decus^ 3ates the larger, and is inserted into the twelfth rib. MUSCLES OF THE ABDOMEN. 347 inch or more in breadth from the symphysis pubis and the upper posterior part of the body of the pubes. The muscle increases gradually in its ascent to the breadth of three or four inches. The tendinous intersections, confining it to the tendinous sheath in front are established at the places men- tioned as lineae transversa^, but, for the most part, they de not extend through the muscle. When the origins of the Recti are examined from behind, it will be seen that the in- ternal edge of one tendon, just above the symphysis pubis, overlaps the corresponding part of the otlier; also that a small pyramidal ligament finishes more completely the struc- ture just above the symphysis pubis ; this ligament is called by Mr. G. Breschet, the Superior Pubic. It is inserted fleshy, into the cartilago ensiformis and into the cartilages of the fifth, sixth, and sev nth ribs. It draws the thorax towards the abdomen.* 5. The Pyramidalis, Is at the lower front part of the rectus. It arises some- what thick, tendinous, and fleshy, from the upper part of the pubes, from near its spine to the symphysis, between the rec- tus behind and the insertion of the external oblique before. It is fixed in a sheath formed by the separation of the ten- dons of the broad muscles. It tapers to a point above, and is inserted into the linea alba and internal edge of the rectus, half way between the umbilicus and the pubes. It strengthens the lower part of the abdomen. + At the linea semilunaris the tendon of the internal oblique and of the transversalis, unite intimately, and just beyond this junction two lamina are formed, which enclose the rec- * Varieties. If there are eight sternal ribs, then this muscle has an addi- tional costal insertion. It sometimes sends a fasciculus to the fourth rib, and I have seen it ascending over the pectoralis major, to the root of the4neck, as occurs in mammiferous animals. j- Varieties. It is frequently defective; but sometimes two, three, or even four, are seen on a side. When defective, the Teotus orobliquus internus i* better developed than usual. 348 MUSCLES. tus muscle. The anterior lamina is one half of the tendon of the internal oblique, which, after passing half an inch or an inch, is joined to the tendon of the external oblique, goes in front of the rectus muscle, and covers it from origin to insertion. The posterior lamina, made by the posterior half of the tendon of the inlernal oblique, is united already at the linea semilunaris to the tendon of transversalis; in this manner they pass behind the rectus muscle from the cartilago ensiformis to a line half-way between the umbilicus and the pubes. From this line, downwards, all the tendons go in front of the rectus muscle. The obliquus externus tendon may, however, be dissected from the common tendon of the others, without much difficulty, almost to the linea alba. The term insertion expresses, very imperfectly, the manner in which the tendons of these broad muscles all terminate in the linea alba from the thorax to the pelvis. The Cremaster Is commonly attributed exclusively to the internal oblique, as it is said to be a detachment of fibres from it; but it is also formed by fibres from the lower edge of the transver- salis muscle. The history of its formation is as follows : in the descent of the testicle, the latter has to pass beneath that edge of the transversalis and of the internal oblique which is extended from the upper part of Poupart's ligament, to the spine of the puhes. As the testicle descends it comes in contact with a fasciculus of these fibres, and takes it along. This constitutes the Cremaster muscle, which, in adult life, and in a strong muscular subject, is seen descending on the outside of the spermatic chord, and spreading over the ante- rior part of the tunica vaginalis in arches with their convex- ities downwards, then rising on the inner side of the chord and inserted into the spine of the pubes.* It draws up the testicle. * Anat. De L'Homme,par Jul. Cloquet. This account, though easily veri- fied in some subjects, and especially in such as are muscular, does not appear MUSCLES OF THE ABDOMEN. 349 Fascia Transversalis Abdominis. The Fascia Transversalis is placed immediately behind the transversus muscle, between it and the peritoneum. An open- ing in it, which permits the spermatic chord to pass, is called the Internal Abdominal Ring, in order to distinguish it from the opening in the tendon of the external oblique, called the External Ring. The internal ring is rather nearer to the symphysis pubis than to the spine of the ilium. The space between the internal ring and the external ring, is about eigh- teen lines in the adult, and is very properly called the Abdo- minal Canal, from giving passage to the spermatic chord. The anterior side of the canal is formed by the tendon of the ex- ternal oblique; the inferior part in the erect posture, is formed by Gimbernat's ligament; the posterior parietes are formed by the fascia transversalis; and above, this canal is over- hung by the internal oblique and the transversalis muscle. The spermatic chord, after penetrating the fascia transversa- lis, does not cross, directly at right angles, the inferior edge of the internal oblique and transversalis, but it slips under them very obliquely, its inclination being towards the pubes, so that it can be considered as disengaged from the inferior edge of these muscles, only about the middle of the abdominal canal. The opening in the Fascia Transversalis. or the Internal Ring, is not abrupt and well defined; but the fascia, where to be applicable to all, or, in other words, the arrangement in them is not quite so obvious. It does not agree with Mr. Jno. Hunter's observations on the descent of the testicle, for he always found, while the latter was still in the loins, the cremaster running towards it. Moreover, in the bufl'alo of America, in which 1 lately had an opportunity of examining this arrangement, through the politeness of my friend Dr. Harlan ; the cremaster, which is re- markably robust and strong, forms none of those nooses or arches with their convexities downwards, but terminates at the testicle in a tendinous and somewhat abrupt manner. Taking all these points into consideration, it may be, that a part of the cremaster is formed after the manner indicated by Mr. Hunter, and another part after that mentioned by M. Cloquet; or, indeed, cases may occur, presenting exclusively one or the other. 350 MUSCLES. it transmits the spermatic chord, is reflected by a thin process and terminates insensibly on its cellular substance. At the posterior or ventral face of the External Ring, the fascia transversalis is not in contact with the chord, but that part of the tendon of the internal oblique and transversalis which is inserted into the crista of the pubes, and forms a sheath for the pyramidalis muscle, is placed between them, and secures this opening. The Peritoneum covers the posterior face of the fascia tranversalis, and is thrown, on either side, into a duplicature or falciform process, passing from near the middle of the cru- ral arch towards the umbilicus. This duplicature depends upon the umbilical ligament of the bladder, which was once the umbilical artery of the foetus. It is broader near the pel- vis than it is above, has its loose edge turned towards the ca- vity of the abdomen, and ascends near the pubic margin of the Internal Ring. The effect of its existence is to divide the posterior face of the inguinal region into two shallow fossae; one next to the ilium, and the other next to the pubes. The one next to the ilium contains the beginning of the internal abdominal ring, which is frequently marked by a little pouch of peritoneum, going along the spermatic chord for a few lines. The fossa on the inner or pubic side of the falciform process is just behind the external ring, but separated from it by the fascia transversalis, along with the tendon of the lower part of the internal oblique and of the transversalis muscle where it is inserted into the pubes, and forms the sheath of the pyra- midalis. The two fossae indicate the points where inguinal hernias commence; the proper inguinal protrusion begins in the external fossa, and the ventro-inguinal in the internal fossa. The view of the fascia transversalis from behind is ex- tremely satisfactory. For a proper knowledge of this mem- brane, the profession is indebted to the labours of Sir Astley Cooper; and much of the zeal with which the anatomy of her- nia has been investigated, in latter years, is attributable to him. The fascia transversalis is a thin tendinous membrane most generally, occasionally it resembles more, condensed MUSCLES OF THE ABDOMEN. 351 cellular membrane. It arises from the internal or abdominal edge of Poupart's ligament, and from the crista of the pubes just behind the insertion of the common tendon of the inter- nal oblique and transversalis muscles, and is extended up- wards on the posterior face of the transversalis muscle to the thorax. At its origin it is attached to the inferior edge of the transversalis and internal oblique, particularly the part be- tween the internal ring and the symphysis pubis. It is also attached to the exterior margin of the rectus abdominis. The internal abdominal ring or opening in this fascia marks it out in some measure into two portions, of which that on the iliac side of the ring is not so thick as the other, or the one on its pubic side; and both portions are much more tendinous near the crural arch, than they are higher up. Were it not for the important influence of the fascia super- ficialis abdominis and the fascia transversalis upon hernia, and the consequent necessity of a minute knowledge of them, their description might be much curtailed in considering them in their proper light, to wit: as sheaths of the abdominal mus- cles; for it is now sufficiently apparent that the first is con- tiguous to the external oblique, and the second to the trans- verse muscle. Upon the same principle, fasciae might be made of all the laminae of cellular substance intermediate to the ab- dominal muscles, but it would be useless. On removing the peritoneum from the iliacus internus mus- cle, the spermatic vessels are seen to descend from the loins to the internal ring, where they are joined by the vas deferens coming from the pelvis. As they engage under the edge of the internal oblique muscle, after penetrating the ring, the cre- master muscle is detached to spread itself over them. The spermatic chord, thus constructed, passes through the abdomi- nal canal in the manner mentioned, obliquely down wards and inwards; and emerging from the external ring it descends vertically, lying rather upon the outer column of the ring than upon its base. On the posterior face of the fascia transversalis, between it and the peritoneum, is the Epigastric Artery- The epi- 352 MUSCLES. gastric arises from the external iliac as the latter is about to go under the crural arch ; it ascends inwardly along the in- ternal margin of the internal abdominal ring to the exterior margin of the rectus abdominis muscle, which it reaches after a course of two and a half or three inches. The sper- matic chord, in getting from the abdomen to the abdominal canal, therefore, winds, in part, around the epigastric artery, in the first of its course being at the iliac edge of the artery and then in front of it. Two epigastric veins attend the artery, one on each of its sides, and end by a common trunk in the external iliac vein. The anatomical arrangement of the parts concerned in in- guinal hernia in the female is the same as in the male, except that the round ligament of the uterus supplies the place of spermatic chord, and there is no cremaster muscle. SECT. III.--MUSCLES OF THE CFTER AND POSTERIOR PA- RIETES OF THE ABDOMEN. These muscles are constituted by a single symmetrical one, and by four pairs ; they can only be seen advantageously by removing the abdominal viscera. 1. The Diaphragm, (Diaphragma,) Is a complete, though moveable septum, placed between the thoracic and abdominal cavities ; it is extremely concave below and convex above, the concavity being occupied by several of the abdominal viscera. It is in contact above with the pericardium and lungs, and below with the liver, spleen, and stomach. It is connected with the inferior margin of the thorax on all sides, and has for its centre a silvery tendon resembling in its outline the heart of a playing card. This cordiform tendon occupies a considerable part of the extent of the dia- phragm, has its apex next to the sternum and its notch to- MUSCLES OP THE PARIETES OF THE ABDOMEN. 353 wards the spine ; and the muscular part of the diaphragm is inserted all around into its circumference. The cordiform tendon is nearly horizontal in the erect posture, its elevation being on a line with the lowest end of the second bone of the sternum. On each side of this tendon some of the muscular fibres rise so high upwards before they join it, that they are on a horizontal level w ith the anterior end of the fourth rib. The fasciculi of muscular fibres are, for the most part, con- vergent from the circumference of the thorax, and are easily separated from one another. In the diaphragm are three remarkable foramina. The first (the Foramen (Ksophageum) is in the back of the muscle, between the spine and the notch of the cordiform tendon, a little to the left of the middle line. It gives passage to the oesophagus and the par vagum along with it, and is rather a fissure or a long elliptical foramen made by the separation and reunion of the muscular fibres ; for above and below at each end of the ellipsis these fibres decussate one another in columns. To the right of this foramen and a little above its horizontal level in the back part of the cordiform tendon, is a very large and patulous foramen for the ascending vena cava, (Foramen Quadratum.) Its form is between an irre- gular quadrilateral figure and a circle; its edges are com- posed of fasciculi of tendon rounded off, and are not suscep- tible of displacement, or of alteration in their relative position to each other; by which means is obviated any im- pediment which might arise from a different arrangement, to the course of the blood in the ascending cava. Almost in a vertical line below, about three inches from the fora- men for the (esophagus, is the third hole in the diaphragm, which affords passage to the aorta, (Hiatus Aorticus.) It is just in front of the bodies of the three upper lumbar vertebra, and is a much longer elliptical hole than the oesophageal; its lowest extremity or pole is constituted by the tendinous crura of the diaphragm, and its upper by a decussation of muscular fasciculi arising from them. Through it, besides the aorta, pass the Thoracic Duct and the Cxreat Splanchnic Nerve of both sides. vol. 1.—T y 354 MUSCLES In the horizontal position of either the dead or the living body, the right side of the diaphragm ascends higher in the thorax than the left, but the weight of the liver makes it, in the vertical posture, descend lower than the other. Thus circumstanced, the detailed origin of the Diaphragm is as follows. It arises fleshy from the internal face of the upper edge of the Xiphoid Cartilage, from the internal face of the cartilages of the seventh true, and from the succeeding false ribs, on each side: that is, from the cartilages of the eighth and ninth, from the osseous extremities of the tenth and eleventh, and from both the osseous and cartilaginous termination of the twelfth rib. As the line described includes almost the whole of a circle, and the fibres all converge to the cordiform tendon, they, of course, will pass in different radiated directions and be of different lengths, which it is unnecessary to specify. Between the sternal and costal por- tions, on each side, there is a triangular fissure filled with fatty cellular tissue, which sometimes leaves an opening for hernia. I have seen a case of the kind, in which the trans- verse part of the Colon was the subject of protrusion into the thorax. It is probable that the great displacement of the ab- dominal viscera into the thorax, which sometimes occurs, mav have a congenital origin in this very fissure, and is subse- quently, when the parts are accommodated to their unnatural situation, set down as a lusus naturae. The portion described is called the Greater muscle of the diaphragm. Besides these origins, the diaphragm has several from the vertebrae of the loins, constituting its crura; there being four, on each side of the foramen for the aorta. The first pair, en- tirely tendinous, comes from the front of the body of the third vertebra of the loins, and is prevented from being very dis- tinct in its origin, in consequence of running into the liga- ment in front of the bodies of all the vertebra. The second pair of heads is on the outside of the first, and arises tendi- nous from the intervertebral ligament, between the second and third vertebrae. The third pair of heads arises tendinous from the u» per part of the lateral margins of the second lum- bar vertebra. And the fourth pair of heads comes also ten- MUSCLES OF THE PARIETES OF THE ABDOMEN. 355 Vinous from the fore part of the roots of the transverse pro- cesses of the second lumbar vertebra. These tendinous heads terminate in what is called the Lesser muscle of the dia- phragm, which is inserted into the notch of the cordiform tendon. It will now be understood that the aorta passes between the two sides of the lesser muscle, and that the oeso- phagus has a hole in the upper part of its belly.* The origin of the diaphragm is completed between its greater and lesser muscles, by a tense ligament, the Liga- mentum Arcuatum, which passes from the root of the trans- verse process of the first lumbar vertebra to the inferior part of the middle of the twelfth rib; with the upper edge of this ligament the diaphragm is connected; and with the lower, the psoas magnus muscle. At the margin of the other ribs, the diaphragm is connected with the transversalis abdominis. Use. In consequence of the muscular fibres of the diaphragm passing in a curved direction from the circumference of the thorax to the cordiform tendon ; and of those fibres forming a body concave below and convex above, their contraction at the same moment enlarges the cavity of the thorax, and has a tendency to diminish that of the abdomen, which latter is prevented by the yielding of the abdominal muscles. In easy respiration, its contractions and relaxations produce alternately the actions of inspiration and of expiration. Its descent, also, assists in the expulsion of foecal and other mat- ters from the abdomen. By the experiments of Bourdon,f it appears that it only acts a secondary part in the latter,— that its functions are limited to inspiration and the associated actions; but, that in regard to its power of assisting in the expulsion of the contents of the abdomen, all that it does is first of all to fill the lungs with air, and then the closure of the glottis prevents the air from being expelled from the lungs. Common observation in parturition shows us, that • This origin of the lesser muscle of the diaphragm is given by Albinus, but it is difficult to make out fairly; for the most part it would be much more correct to say that it arises tendinous, from the first, second, and third verte- brse. The heads are occasionally much smaller on one side than the other f Recherches sur la Respiration et la Circulation. Paris, 1820. 356 MUSCLES. the expulsive effort of the abdominal muscles does not take place when inspiration is going on, for the former would pre- vent the latter; but, the moment that expiration begins, it is arrested by the firm closure of the glottis, and then the abdo- minal muscles contract advantageously. The Quadratus Lumborum, Is an oblong muscle, arising from the spine of the ilium, at its back part, by a tendinous and fleshy origin of two inches in length. Lying at the side of the lumbar vertebrae, it is inserted into the transverse process of each of them by short tendinous slips; it is also inserted into the lower edge of the last rib near its head, and into the transverse process of the last vertebra of the back. It bends the loins to one side, and draws down the last rib. It is covered behind by the tendinous origin of the trans- versalis abdominis, which separates it from the sacro lum- balis and from the longissimus dorsi. It may also he seen very well from behind, in the dissection of the back.* The Psoas Magnus, Arises, fleshy, from the side of the bodies of the last dorsal and of the four upper lumbar vertebrae, and from the trans- verse processes of all the lumbar vertebrae. It forms an oblong fleshy cushion on the side of the lumbar vertebrae, and, constituting the lateral boundary of the inlet to the pel- vis, it passes out of the pelvis, under Poupart's ligament, about its middle. It is inserted tendinous, into the trochanter minor of the os femoris, and fleshy for an inch below it. • Varieties. Sometimes a broad tendon from it is inserted into the inferior margin of the body of the eleventh vertebra of the back. Sometimes a fasci- culus of it touches the margin of the eleventh rib, near its head, and above the intercostal vessels. MUSCLES OF THE PARIETES OF THE ABDOMEN. 357 It bends the body forwards, or draws the thigh upwards.* The Psoas Parvus, Arises, fleshy, from the contiguous edges of the last dorsal and of the first lumbar vertebra at their sides, and from the intervertebral ligament. It is at the anterior and internal edge of the psoas magnus; has a short belly, and a long ten- don by which it is inserted into the linea innominata, about half-way between the spine of the pubes and the junction of this bone with the ilium. The tendon, besides, is expanded into the fascia iliaca. Its use seems to be, to draw upwards the sheath of the fe- moral vessels, which is derived from the fascia iliaca, and consequently to draw upwards the vessels themselves, which probably diminishes the liability to injury from their too great or sudden flexion. This muscle is sometimes wanting. The Iliacus Internus, Occupies the concavity of the ilium, being on the outside of the psoas magnus. It arises, fleshy, from the transverse process of the last lumbar vertebra; from the internal margin of the crista, of the ilium ; from the whole concavity of the latter; from its anterior edge at and above the anterior infe- rior spinous process ; and from that part of the capsule of the hip joint near the latter process. This muscle terminates in the tendon of the psoas magnus, just above the insertion into the trochanter minor. This and the psoas magnus, from having a common tendon, might with propriety be considered as only one muscle. Their action is the same.f * Varieties. Sometimes it is joined by muscular fasciculi from the first, second, and even the third bone of the sacrum. Sometimes, where it bor- ders on the pelvis, there is a small fasciculus, which continues distinct almost to the trochanter minor, and then sends its own tendon into the common tendon of the iliacus internus and psoas magnus. t Varieties. Sometimes an additional fasciculus arises below the inferior 35S MLSCLES. Of the Fascia Iliaca. The Fascia Iliaca is a tendinous membrane, which lies on the iliacus internus and psoas magnus muscles, and is conti- nued into the tendon of the Psoas Parvus. Externally it in connected to the margin of the crista of the ilium ; at the in- ternal edge of the psoas magnus it is connected with the brim of the pelvis, and sinks into the cavity of the pelvis, being continuous with the Aponeurosis Pelvica; and below, it is inserted into the edge of the crural arch, from the anterior superior spinous process of the ilium almost to the pubes, and is there continuous w ith the fascia transversalis abdominis. The external iliac vessels are upon this fascia, between it and the peritoneum ; and below them the fascia iliaca goes over that part of the pubes which gives origin to the pectineus muscle, and is continuous with the pectineal fascia, or that which covers the pectineus muscle. By introducing the finger or a knife handle into a cut through the fascia iliaca, its at- tachment to the crural arch, and its continuity with the fascia pectinea, will be rendered very obvious. The iliac vessels pass beneath the crural arch on the inner margin of the psoas magnus muscle, the vein being nearest the pubes and the artery at the outer side of the vein. The fascia iliaca is inserted into the crural arch as far as the vein, and may indeed be traced to the crista of the pubes; it is so connected with the vessels that no opening for hernia exists between them, or indeed in all the space from the internal margin of the vein to the spine of the ilium. But at the inner side of the vein, between it and Gimbernat's ligament, an opening appears called the Crural or Femoral Ring, and is the place where femoral hernia commences. This opening is generally occupied by a lymphatic gland, and a lamina of anterior spinous process, and descends along the external margin of this muscle. This fasciculus varies somewhat in its size at different points, and is inserted into the linea aspera below the trochanter minor. In very rare cases the iliacus internus is kept totally distinct from the psoas magnus, from origin to insertion. MUSCLES OF THE THORAX. 359 condensed but loosely attached cellular substance, continuous with the Aponeurosis Pelvica. SECT. IV.--MUSCLES ON THE ERONT OF THE THORAX. The Pectoralis Major, Is superficial, and forms the large swelling cushion of flesh under the skin of the breast. It arises tendinous from the anterior face of the sternum, its whole length, fleshy from the cartilages of the fifth and sixth ribs, and by a fleshy slip from the upper part of the tendon of the external oblique muscle. It arises also fleshy from the interior two thirds of the clavi- cle. The clavicular and sternal portions of the origin are separated by an interval, giving the appearance of two mus- cles. The fibres converge and terminate by a broad, thin tendon, which is inserted into a roughness on the exterior edge of the bicipital fossa of the os humeri; and into the fascia brachi- alis, just at the internal edge of the deltoid muscle. It ad- heres to the tendon of the latissimus dorsi. The under edge of the muscle, near its insertion, is folded inwards and up- wards, which gives the rounded thick margin to the fore pari of the axilla. That part of the broad tendon belonging to the clavicular portion, is inserted lower down than the sternal, which produces a decussation of the fibres of the tendon. The Pectoralis Major draws the arm inwards and for- wards, and also depresses it when it is raised.* ' Varieties. Sometimes a single fasciculus arises from the «ghth rib, which ascends towards the os humeri, has a tendon in its centre, and finally joins with the tendon of the pectoralis minor;—sometimes this muscle de- taches a small fasciculus to the brachialis internus;—sometimes there is a small square plane of muscular fibres on its front surface, decussating the fibres at right angles;—sometimes a fasciculus almost cylindrical proceeds from it towards the axilla, and being changed into a long tendon is in- serted into the internal tuberosity of the os humeri. Supernumerary fas- ciculi are also found going from one rib to another, or towards the sternum; sometimes its tendon detaches a fasciculus, which, crossing the insertion of StiU .MLSCLE.1! The Pectoralis Minor, Is brought into view by raising the last muscle. It is com- paratively small and somewhat triangular, arising by thin tendinous digitations from the upper edges of the third, fourth, and fifth ribs. It soon becomes fleshy, and is inserted, by a short flat tendon, into the inner facet of the coracoid process of the scapula. Its use is to draw the scapula inwards and downwards.* The Subclavius, Is a small muscle placed immediately under the clavicle. It arises from the cartilage of the first rib, and is inserted into the inferior face of the clavicle from near the sternum to the conoid ligament, which connects the coracoid process and the clavicle together. It draws the clavicle downwards.f The Serratus Magnus, Is a broad muscle lying on the sides of the ribs, between them and the scapula, and beginning at a line anterior to their middle. It arises from the nine upper ribs by fleshy digitations, the superior one of which seems almost like a distinct muscle; and the five lower are connected to the ob- liquus externus abdominis, the digitations of the two muscles the muscle, covers the bicipital groove of the os humeri like a bridge, is blended with the tendon of the supra-spinatus, and increases the thickness of the capsular ligament of the shoulder joint. * Varieties. Sometimes it sends a fleshy fasciculus to the tendinous origin of the coraco brachialis. Sometimes below it, there is a third pectoral mus- cle, which arises from the first and second ribs, and is inserted into the co- racoid process; whereby a striking analogy with birds is established. An- other variety has also been observed in the existence of a fasciculus, which comes from the upper rib, and which, covered by the little pectoral muscle, . is inserted into the capsular ligament of the scapulo-humeial articulation. f Varieties. Sometimes two muscles exist; a bursa mucosa is formed be- tween its tendon and the cartifagc of the first rib. MUSCLES OF THE THORAX 361 interlocking with each other. The fibres converge, and are inserted into the base of the scapula its whole length. Its action is to draw the scapula forwards.* s~ The Intercostales, Fill up the spaces between the ribs. There are two in each space. The External arises from the spine and from the in- ferior acute edge of each rib almost to its cartilage, and is inserted into the superior rounded edge of the rib below for the same distance, its fibres passing obliquely forwards and downwards. The Internal Intercostal arises from the infe- rior edge of the rib, beginning at the sternum, and going backwards to the angle of the rib ; it is inserted into the supe- rior rounded edge of the rib below on its inner side, its fibres passing obliquely backwards and downwards. They draw the ribs together. The Triangularis Sterni, Is on the posterior or cardiac face of the cartilages of the ribs, and arises from the whole length of the cartilago ensi- formis at its edge, and from the inferior half of the edge of the second bone of the sternum. The fibres go obliquely up- wards and outwards to be inserted into the cartilages of the third, fourth, fifth, and sixth ribs by fleshy and tendinous digitations. Its use is to depress the ribs, and consequently to diminish the cavity of the thorax. This muscle is frequently defective or redundant in the number of its heads, and is commonly more or less conti- nuous with the transversalis abdominis; but occasionally it is so much so, that the two seem to make but one muscle, • Varieties. Sometimes, it has ten or eleven origins; the upper origin is deficient; the latter is so distinct that it may pass for a particular muscle; a wide gap exists in the middle of the muscle, dividing it into two distinct parts. VOL I.--Z 7. 262 MUSCLES. and have therefore been called Stcrno-abdominalis, by Rosen - >muller. CHAPTER II. MUSCLES OF THE NECK AND FACE SECT. I.—MUSCLES OF THE NECK. Of the Fascia Superficialis Colli. Between the skin of the neck and its superficial muscles, may be observed a layer of compact cellular substance, the consistence of which is more strongly marked in some sub- jects than in others. It is the continuation of the same mem- brane which is spread upon the external abdominal muscles, and is called there the Fascia Superficialis Abdominis. Pass- ing from the abdomen over the thorax, it adheres to the cla- vicles and sternum, but not very strongly; it then goes from them over the neck to the face, being slightly fastened to the base of the lower jaw in advance of the masseter muscle. It is spread over the submaxillary and parotid glands, and sends down partitions between their lobules; as well as be- tween the muscles and their fasciculi, thereby forming sheaths for the same. By these partitions it communicates with the fascia profunda colli. Above, it is fixed to the mastoid pro- cess, to the meatus auditorius externus, and to the zygoma. Just above the latter it adheres to the fascia temporalis, a thin layer of fat intervening between them. This fascia is more strongly characterized about the parotid gland and lower jaw than elsewhere. It is remarkably distinct in the foetus at full time, the sheaths which it forms for the muscles being then very clear of adipose matter, and semidiaphanous. MUSCLES OF THE NECK. 363 The Platysma Myoides, t)r the Musculus Cutaneus, is immediately beneath the fascia superficialis ; covers, by its breadth, a very considera- ble portion of the side of the neck; and extends obliquely, from the thorax to the face. It arises from the condensed cellular membrane on the up- per part of the pectoralis major muscle, and of the deltoid, just below the clavicle, and nearly the whole length of this bone Its fibres are much more pale than those of other voluntary muscles, are collected into longitudinal fasciculi, constituting a plane of scarcely a line in thickness, and ter- minate in the integuments of the lower jaw and cheek. It is slightly attached to the lower jaw, and not unfrequently runs into the muscles of the lower part of the face. When the whole muscle is in action it elevates the skin of the neck. The external jugular vein is seen running nearly in the centre of it in the same direction with the fibres of this muscle, and between it and the sterno-mastoid.* The Sterno-Cleido Mastoideus, Is beneath, and decussates the last muscle. It forms al- ways a prominent feature in the outline of the neck, in passing obliquely from the upper front part of the thorax to the base of the cranium. It arises tendinous and fleshy from the edge of the upper part of the sternum, and fleshy from the sternal end of the clavicle. These origins are separated by a considerable fis- sure; they soon unite, and are inserted tendinous into the mastoid process, and into a part of the transverse ridge of the occipital bone next to it. It draws the chin towards the sternum, f • Varieties. In some very rare instances this muscle has been found thick and round; and instead of going towards the face, inserted into the occiput. \ Varieties. Sometimes a fasciculus, at its posterior margin, is presented in a state entirely insulated. Occasionally its lower extremity has been ob- served to reach as far as the rectus abdominis muscle, and even to the point 364 MUSCLES. Of the Fascia Profunda Colli. When the origin of the sterno-cleido-mastoideus is turned to one side, the Fascia Profunda of the neck is seen beneath the fascia superficialis, and somewhat separated from it by a lamina of cellular adipose matter. This membrane arises from the larynx, forms a thin capsule to the thyroid gland, and, being closely attached to its inferior margin, descends by investing the sterno-hyoid and thyroid muscles, being strong and well marked on their anterior surfaces. It is firmly fastened to the upper edge of the sternum, to the ster- nal end of the clavicle, and to the cartilages of the first ribs, forming an elastic and resisting membrane from the larynx to the thorax. By turning off the sterno-hyoid and thyroid muscles from their attachment to the sternum, the fascia pro- funda will be seen, still more distinctly, passing behind them from the inferior margin of the thyroid gland, to the upper bone of the sternum; this lamina of it is inserted into the ster- num, twelve or fifteen lines below its upper edge. It encloses or surrounds the transverse vein and the arteria innominata. Beneath the fascia profunda, are the trachea, the roots of the arteries of the head and upper extremities, and the trunks of their veins. There is much loose cellular and adipose matter placed at the lower part of the neck, beneath this fascia; and between it and the trachea; through which the thyroid veins with their ramifications pass. This last circumstance must always render suppurations and operations in the part highly dangerous, as the pus will form fistula? under the sternum; moreover, the continual motion of the part in respiration, prevents adhesion from forming, and, therefore, disposes to ulceration. An ingenious idea on the uses of this fascia and of the sterno-hyoid and thyroid muscles as connected with it, was suggested by the late Allan Burns; he conceived that they were a defence to the upper part of the thorax, and of the third bone of the sternum. The fissure between the sternal and clavicular portions, in mammiferousanimals, i», naturally, so much extended, as to produce two distinct muscles. MUSCLES OF THE NECK. 365 sustained, in inspiration, the atmospheric pressure, which, without them, would fall upon the trachea and produce dif- ficulty of breathing, from the air not passing through the larynx sufficiently rapidly to keep pace with the dilatation of the thorax. He illustrates the opinion by a case very much in point, of a gentleman who had lost this fascia and the muscles by suppuration, and who was afterwards in- commoded by atmospheric pressure upon the trachea at this place.* The external borders of the fascia profunda are continued into the sheaths of the great vessels of the neck. It and the fascia superficialis are also continuous with one another along the anterior edge of the sterno-cleido-mastoideus. Within the inferior maxilla, at its angle, a ligamentous ex- pansion arises from the pterygoideus externus muscle, and is spread out between the styloid process, and the ramus of the lower jaw. This membrane is joined at its inferior edge by the fascia superficialis, just before the upper part of the sterno-mastoideus; which increases its breadth downwards in the neck, giving it somewhat the condition of a vertical septum of that region; at its lower edge it runs into the theca of the great vessels of the neck. Through its lower part penetrate the stylo-hyoideus and digastricus muscles, and the upper part separates the parotid from the submaxil- lary gland. It is felt like a cord extending downwards and backw ards below the angle of the maxilla inferior. It is connected at its internal edge with the compages of the nerves and vessels of the part in such a manner as to forbid descrip- tion, but the practical anatomist will find no difficulty in dis- covering and understanding it. Below this septum the round ligament, like a nerve, passes from the extremity of the styloid process to the appendix of the os hyoides. • The late Dr. Lawrence informed me that the fascia profunda is well de- veloped in the neck of a cat, and that having occasion to remove it in an ex- periment, the respiration of the animal was conducted with great difficulty, amounting almost to suffocation. This is a good confirmation of Mr. Burns's hypothesis. 366 MUSCLES. The fascia profunda colli, is also well marked in the foetus, and not much blended with adipose matter. It, like the fas- cia superficialis, is only the sheath for the muscles which it surrounds, and is called fascia from having an unusual de- velopment of fibrous matter in its substance. The Sterno Hyoideus", Arises thin and fleshy on the interior of the thorax from the approximated surfaces of the cartilage of the first rib, the clavicle, and the first bone of the sternum ; it passes up- wards somewhat obliquely, and is inserted into the inferior edge of the base of the os hyoides. Its lower end is covered by the sterno-mastoideus. It draws the os hyoides towards the sternum.* The Sterno Thyroideus, Is beneath the last, and concealed, in a considerable degree, by it. It arises fleshy from the interior surface of the ster- num, about an inch below its upper margin, and from the cartilage of the first rib; diminishing somewhat in breadth, as it ascends, it is inserted obliquely into the side of the thyroid cartilage. It draws this cartilage towards the sternum, f 4. The Thyreo Hyoideus, Arises obliquely from the side of the Thyroid Cartilage externally, and is inserted into a part of the base, and into * Varieties. Sometimes, it arises from the middle of the clavicle ; it is double ; or is confounded below with the next muscle. ■j- Varieties. Sometimes there are two of these muscles, one placed above the other; sometimes it runs into the inferior constrictor of the pharynx; sometimes it runs into the posterior margin of the hyo-thyroid muscle; sometimes the muscle on one side is united to the other by transverse fibres. MUSCLES OF THE NECK 867 all the cornu of the os hyoides. It seems almost like a con- tinuation'of the Sterno-Thyroideus. Its use is to approximate the os hyoides and the thyroid cartilage, in doing which, it has the effect of planting the epiglottis against the root of the tonge, and of drawing the cricoid and the arytenoid cartilages against it, so that the opening of the glottis is protected.* The Omo-Hyoideus, Passes obliquely across the neck, from the superior edge of the scapula to the os hyoides. It is a thin, narrow mus- cle, divided into two bellies, one at each end, by an interme- diate tendon, its inferior part is concealed by the trapezius muscle, its middle, where the tendon exists, crosses the great vessels of the neck, and is covered by the sterno-cleido-mas- toid muscle, and its upper extremity is overlapped by the platysma myoides. It arises from the scapula just behind the notch in its supe- rior costa, and curving somewhat downwards in its course, it is inserted into the lower edge of the base of the os hyoides, next to its cornu. It draws the os hyoides downwards.j The Digastricus, Is placed at the upper side of the neck, and passes from the back part of the base of the head to the chin. It arises principally fleshy from the fossa of the temporal bone at the base of the mastoid process ; its middle is con- verted into a round tendon, whiah passes through the stylo- hyoideus muscle, and is fixed by a ligamentous loop to the cornu of the os hyoides. After which another fleshy belly • Varieties. Its fibres sometimes run into those of the middle constrictor of the pharynx; sometimes they arise from the cricoid cartilage; sometimes it is continuous with the sterno thyroideus. f Varieties. Sometimes it is double, so that besides the usual insertion, it has one into the side of the tongue. 368 ;,scles. is formed, which is inserted into the inside of the base of the maxilla inferior, at the side of its symphysis. It receives an accession from the base of the os hyoides. Its use is to draw the os hyoides upwards when the ex- tremities are fixed, and, as Mr. Hunter has pointed out, to throw the head backwards and thereby to open the mouth when the lower jaw is fixed upon a body of the same height.* The Stylo Hyoideus, Is the more superficial of the three styloid muscles. It arises tendinous from the middle and inferior part of the styloid process of the temporal bone, and being perforated, as mentioned, by the tendon of the digastricus, is inserted tendinous into the cartilaginous juncture of the base and cornu of the os hyoides. It draws the os hyoides upwards and backwards.f The Slylo Glossus, Is within and above the other; it arises from the upper internal part of the styloid process, tendinous and fleshy, and is inserted into the side of the root of the tongue, form- ing a part of its structure.^ It draws the tongue backwards.^ The Stylo Pharyngeus, Is more deeply situated than either of the other two mus- cles. It arises from the inner side of the styloid process near its root, and runs into the side of the pharynx between * A common variety in this muscle consists in the mutual adhesion of the two anterior bellies belonging to the opposite sides, showing thereby a marked tendency to the quadruped arrangement. f Varieties. This muscle is frequently double. t See Tongue. § Varieties. J. F Meckel says, that on one occasion he found it doub!* on both sides. MUSCLES OF THE NECK. 363 the middle and upper constrictors, opposite the tonsil gland, it afterwards descends between the lining membrane of the pharynx and the middle and lower constrictors, and is in- serted into the posterior margin of the thyroid cartilage. It draws the larynx and pharynx upwards. The Mylo Hyoideus, Forms the floor of the mouth and suspends the tongue; it arises at the root of the alveolar processes of the lower jaw, from a ridge extending from the last dens molaris to the chin. Its fibres converge, towards a white tendinous line placed between it and its fellow and reaching from the base of the os hyoides to the chin. This muscle is concealed by the anterior belly of the digastricus. When it con- tracts, it draws the os hyoides upwards and projects the tongue.* ^The Genio Hyoideus, Is concealed by the last, by turning over the anterior edge of which it is seen.? It arises tendinous from the tubercle on the side of the symphysis of the lower jaw poste- riorly, and, increasing somewhat in breadth, is inserted into the anterior part of the base of the os hyoides. , It draws the os hyoides upwards and forwards.! (For the muscles of the tongue see Mouth.} There are seven pairs of muscles on the front and sides of the cervical vertebras, which lie closely upon them. They are named from their situations and shapes. * Varieties. Sometimes a part of it is inserted into the middle tendon oS the digastricus, or is joined with the sterno-hyoideus. f Varieties. Sometimes a distinct fasciculus of this muscle is inserted into the greater part of the cornu of the os hyoides. Sometimes there is but one muscle. Rarely it is double on both sides VOL. I. — 3 A 370 MUSCLES. 1. Longus Colli. The Longus Colli is next to the middle line of the verte- brae. It arises from the sides of the bodies of the three supe- rior vertebra of the back, and from the anterior edges of the transverse processes of the five lower cervical vertebral Its fibres pass somewhat obliquely upwards and inwards to be inserted into the front of the bodies of all the cervical ver- tebra. It bends the neck forwards and to one side.* 2. Rectus Capitis Anticus Major, Is placed on the outside of the last. It arises tendinous and fleshy from the fronts of the transverse processes of the third, fourth, fifth, and sixth cervical vertebra ; forms a consider- able fleshy belly, arid is inserted into the cuneiform process of the os occipitis just before the condyle. It bends the head forwards.! ■4 ':, 3. Rectus Capitis Anticus Minor. This- is a very small muscle/ It arises fleshy from the front of the body of the first cervical vertebra near its trans- verse process, and is inserted under the rectus major before the root of the condyloid process of the occipital bone. It bends the head forwards. 4. Rectus Capitis Lateralis. This is also small, and arises fleshy from the front of the transverse process of the atlas. It is inserted tendinous and fleshy, at the outside of the condyle of the occiput, into the ridge leading from it to the mastoid process. • Varieties. Sometimes a fasciculus from the first or second rib,* or from the body of the sixth or seventh'Vertebra of the neck joins it. • f Sometimes it also arises from the first and second vertebrae. MUSCLES OF THE NECK. 371 It pulls the head a little to one side.* 5. Scalenus Anticus. ''' - The scalenus anticus arises by three distinct tendinous heads from the transverse processes of the fourth, fifth, and sixth cervical vertebra, and is inserted tendinous and fleshy into the upper edge of the first rib, just anteriorly to its mid- dle. 6. Scalenus Medius. The scalenus medius arises by distinct tendons from the transverse processes of all the cervical vertebra, and is in- serted tendinous and fleshy into the upper part of the first rib, in all the space from its middle to its tubercle. 7. Scalenus Posticus. The scalenus posticus arises from the transverse processes of the fifth and sixth cervical vertebra, and is inserted into the upper face of the second rib, just beyond its tubercle. The last three muscles are concealed by the sterno-cleido mastoideus and the anterior edge of the trapezius. The Sca- lenus Posticus is best seen in dissecting the muscles of the spine, and resembles very much one of the class to which Albinus gives the name of Levatores Costarum. All the Scaleni elevate the ribs and bend the neck to one side. They are particularly interesting as connected with the course of the large blood-vessels and nerves of the upper extremity.f * Varieties. Sometimes another muscle arises from the body of the first vertebra of the neck. ! Varieties. Besides the three scaleni which are described, there are fre- quently supernumerary muscles or fasciculi. One of these, called the sca- lenus minimus Albini, is between the two first, and occasionally appears as a fasciculus of the scalenus anticus, separated from it by one or more of the brachial nerves; it is sometimes double. Another fasciculus, called the scalenus lateralis, is between the scalenus medius and posticus; it comes 312 MUSCLE'S SECT. II.—MUSCLES OF THE FACE- Occipito-Frontalis. The occipito-frontalis muscle consists of two symmetrical parts, coming from the back of the head, and inserted into the front of it. It is superficial, being placed immediately below the skin of the scalp, and has four bellies of muscular fibres, two behind and two before, connected by a thin tendon, which covers all the top of the head. The tendon adheres very closely to the pericranium below, and to the common integu- ments above. This muscle arises from the superior transverse ridge of the os occipitis by tendinous and fleshy fibres, which form two distinct bellies about an inch and a half long, one on each side of the bone. Its tendon, when carefully traced, will be found terminating a little in front of the coronal suture in the two anterior fleshy bellies which cover the whole front part of the os frontis. The internal edges of these latter are in conjunction below. It is inserted fleshy, on each side, into the superior margin of the orbicularis oculi and of the corrugator supercilii; and by its nasal slip into the internal angular process of the os frontis, and into the root of the os nasi. It pulls the skin of the head backwards and forwards, and throws the forehead into horizontal wrinkles. It also ele- vates the supercilia.* Compressor Naris. The compressor naris arises by a pointed beginning from the root of the ala nasi, and spreads like a fan over the lateral parts of the nose below; it is inserted into its fellow of the op- « from the posterior part of the first rib, and is inserted into the transverse processes of the fourth, fifth, and Sixth vertebrae. * Varieties. Its fleshy portion is said to have covered, in some instances, the whole scull-cap. MUSCLES OF THE FACE. 373 posite side on the dorsum of the nose, and into the lower part of the os nasi, where it is connected with the nasal slip of the occipito frontalis. This muscle consists of thin and pale fibres immediately under the skin. If it act from both extremities, by its curved fibres being made straight, it will compress the nostril; but if it act from its dorsal margin, assisted by the nasal slip of the occipito frontalis, it will dilate the ala nasi, and has, therefore, been called dilatans nasum by Columbus. Orbicularis Palpebrarum. The orbicularis palpebrarum is a broad circular muscle, lying immediately under the skin of the eyelids, and over the tarsi cartilages. It is so much connected with essential points in the anatomy of the eyelid, that the further consideration of it is postponed to that article. See also the same for cor- rugator supercilii. The Levator Labii Superioris et Alas Nasi, Is fixed just at the side of the nose. It arises by a pointed production from the nasal process of the superior maxilla at the internal canthus of the eye, and by a broad origin from the anterior margin of the orbitar process of the same bone. Passing downwards it is inserted into the side of the ala nasi, and into the upper lip, being narrower below than above. It draws the upper lip and the ala nasi upwards. Just beneath this muscle there is sometimes a fasciculus called the Anomalus Faciei of Albinus, which is attached by one end to the upper jaw near the canine fossa, and by the other to the upper lip. The Levator Anguli Oris, Is a small muscle concealed very much by the last; it arises from the anterior part of the superior maxillary bone, 374 MUSCLES. between the foramen infra-orbitarium and the first small grinder, and is inserted into the corner of the mouth. It raises up the angle of the mouth. The Zygomaticus Minor, Is a small muscle arising from the fore part of the os ma- la ; it descends obliquely and is inserted into the upper Kp just above the corner of the mouth.* The Zygomaticus Major, Is just on the outside of the last and much larger. It arises from the malar bone externally, at its posterior infe- rior part just above the lower edge, where this bone contri- butes to form the zygoma. It passes obliquely downwards to be inserted into the corner of the mouth, and runs into the depressor anguli oris. The two last muscles draw the corner of the mouth to- wards the cheek bone, or obliquely upwards and outwards as in smiling. The Depressor Labii Superioris et Alse Nasi. Is concealed by the orbicularis oris and the levator labii superioris et ala nasi. To get a view of it the upper lip must be inverted and the lining membrane of the mouth re- moved on the side of the franum of the lip. This muscle arises from the inferior part of the upper maxilla in front of the alveolar processes for the dens caninus and the incisores, and is inserted into the side of the ala nasi and into the con- tiguous part of the upper lip. It depresses the upper lip and the ala nasi. * Varieties. Frequently it is deficient; sometimes it is a fasciculus of the orbicularis oculi; sometimes it is double; sometimes it does not reach the corner of the mouth. MUSCLES OF THE FACE. 375 The Depressor Anguli Oris, Arises broad and fleshy from the base of the lower jaw on the side of the chin ; being somewhat triangular, its apex is inserted into the corner of the mouth. This muscle draws the corner of the mouth downwards. It lies immediately under the skin, and blends above with the zygomaticus major and with the levator anguli oris. The Depressor Labii Inferioris, Is in part beneath the last muscle, and, like it, arises broad and fleshy from the basis of the lower jaw on the side of the chin ; its fibres pass obliquely upwards and inwards and are inserted into the whole side of the lower lip. It draws the lip downwards. These two last muscles are much obscured by being mixed with a quantity of adipose matter; the skin, also, is closely blended with them, and the roots of the beard penetrate be- tween the intervals of their fibres.* The Levator Labii Inferioris, Being placed beneath the depressor labii inferioris, is de- monstrated by turning downwards the lower lip and dissect- ing away its lining membrane on the side of the franum ; it will then be seen to arise in front of the alveolar process of the external incisor and the canine tooth, and passing ob- liquely downwards to be inserted into the lower lip. It elevates the lower lip. The Buccinator, Arises from the root of the coronoid process of the lower jaw bone ; from the back part of the upper maxilla near the pterygoid process 5 and from the roots of the alveolar pro- * Varieties. Its exterior border is often formed by the Platysma Myoides, 376 MUSCLES. cesses of both bones as far forwards as the dentes bicuspides. It is inserted into the corner of the mouth and into the con- tiguous part of the upper and lower lip. It draws the corner of the mouth directly backwards. The Orbicularis Oris, Is a circular muscle just beneath the skin, much blended with adipose matter externally, but more plain on the sur- face contiguous to the lining membrane of the mouth. It constitutes a considerable part of the thickness of the lips, and surrounds the mouth entirely. It has no bony origin, but arises from the fibres of the several muscles which join each other at the corner of the mouth, and therefore consists of two semicircular planes, one for the upper and the other for the lower lip. It is the antagonist to most of the other muscles of the mouth. From its superior part a pyramidal slit goes to the tip of the nose, called by Albinus Nasalis Labii Superioris?** Masseter. The masseter is placed between the skin and the ramus of the lower jaw; it is of an oblong shape and evidently con- sists in two portions, an external and an internal, which may be readily recognized by the course of their fibres as they decussate. As a whole it arises tendinous and fleshy from the malar process of the upper maxilla; from the inferior edge of the malar bone between the maxillary and the zygomatic sutures, and from the zygomatic process of the temporal bone. Of its two portions the internal is the smaller, and is inserted tendinous into the outer part of the root of the coronoid pro- cess of the lower jaw ; while the external extends from the malar bone to the angle of the lower ^Jaw, where it is in- serted tendinous and fleshy. A part of the internal portion may be seen at the zygomatic suture behind the external, without the latter being raised up. MUSCLES OF THE FACE. S77 When both portions act together they close the jaws; the external alone, draws the jaw forwards; and the internal alone, will draw it backwards. Temporalis. The Temporal muscle is placed on the side of the head and occupies its middle inferior region. It is covered ex- ternally by the Fascia Temporalis, a thick, dense, tendinous membrane; which arises by the semicircular ridge on the side of the cranium, and is inserted into the upper margin of the zygoma. The temporal muscle arises from the inner face of this fascia; from the whole length of the semicircular ridge on the side of the os frontis and parietale ; and from the surface of the cranium between this ridge and the zygoma, including a part of the frontal bone, of the parietal, and of the squa- mous portion of the temporal. This muscle also receives an accession of fleshy fibres from the internal face of the zy- goma. From this extensive origin the fibres converge towards the zygoma, and passing beneath it, are inserted tendinous into the coronoid process of the lower jaw, so as to surround it on every side; some of these tendinous fibres go down in front almost to the last dens molaris. It pulls the lower jaw directly upwards. Pterygoideus Externus. The External Pterygoid muscle, so called from its posi- tion, arises fleshy from the outer side of the external ptery- goid process of the sphenoid bone; from the tuber of the upper maxilla; and from the under surface of the temporal process of the sphenoid bone. It passes outward* and backwards horizontally, and is inserted into the inner side of the neck of the inferior maxilla, and into the capsular ligament of the articulation. When the muscles of the opposite sides act together, they VOL. i.—3 B 378 MUSCLES. draw the lower jaw forwards, but if alternately, they give ii a grinding motion.* Pterygoideus Internus. The Internal Pterygoid muscle arises by tendinous and fleshy fibres from the internal plate of the pterygoid process of the sphenoid bone, along the outer margin of the Eusta- chian Tube. It fills up the greater part of the pterygoid fossa, and pass- ing downwards and backwards, is inserted tendinous and fleshy into the internal face of the angle of the lower jaw.' When the muscles of the opposite sides act they close the jaw. CHAPTER III. OF THE FASCIA AND MUSCLES OF THE UPPER EXTRE- MITIES. SECT. I.—FASCIA. The muscles of each upper extremity are invested by an aponeurotic membrane called the Fascia Brachialis, which extends from the shoulder to the band. It begins at the base and spine of the scapula, the margin of the acromion process, the acromial extremity of the clavicle, and from the cellular membrane in the arm-pit, and extends itself over the mus- cles on the dorsum of the scapula, and over the deltoid mus- cle. It is continuous with an expansion of the tendons of the latissimus dorsi and pectoralis major. Below the spine of the • Varieties. I have seen, in one case, this mu&cle continued into the in- ferior margin of the temporal. FASCIA. 379 scapulaitis strongandwell marked, but on the deltoid muscle* as well as on the muscles of the arm, its desmoid character is by no means so well developed, though it still retains the ap- pearance of a distinct membrane, and can be raised up as such from the muscles. On tlie fore-arm its ligamentous ap- pearance is well preserved, and extends from the elbow joint to the wrist inclusively. Its longitudinal fibres there are well secured by transverse ones. Just above the condyles of the os humeri, where the ridges are which lead to them, the Fascia Brachialis sends down to the bone a strong tendinous partition to each ridge, running the length of the latter from its upper end to the condyle. These processes separate the muscles on the back of the arm from such as are on the front of it, and are sometimes called the ligamentum intermusculare internum and externum. They afford origin to many muscular fibres. At the bend of the elbow, the fascia brachialis is reenforced by a fasciculus of tendinous-matter from the ulnar margin of the tendon of the biceps, which, in the contraction of the muscle, will keep it tense. At the lower extremity of the fore-arm, the transverse fi- bres, after diminishing sensibly, become more numerous, and by their attachments to the several ridges on the back of the radius and on the ulna, form the Ligamentum Carpi Dorsale. This ligament is extended from the styloid or outer margin of the radius, transversely to the styloid or inner margin of the ulna, to the pisiform bone, and to the fifth metacarpal. It consists, in some measure, of two portions: of which the superior is the smaller and the thinner, has its fibres descend- ing from the ulna to the radius, and is crossed, in part, by the fibres of the inferior or greater portion. As this liga- ment adheres, with great strength, to the ridges on the back of the bones of the fore-arms, six trochlea for the tendons of the extensor muscles are thus formed. The first, or that next to the styloid process of the radius, contains the tendons of the two first extensors of the. thumb. The second is larger, and transmits the tendons of the two radial extensors of the carpus. The third is small and oblique, for the tendon of the 380 MUSCLES third extensor of the thumb. The fourth is the largest, ami is for the tendons of the extensor communis of the fingers. The fifth is between the radius and the head of the ulna, and is for the tendon of the extensor communis which goes to the little finger. The sixth is on the back of the ulna, and is for the tendon of the extensor carpi ulnaris. The inferior margin of the dorsal ligament does not ter- minate abruptly, but, resuming its fascia-like character, is continued over the back of the wrist, and over that of the hand to the fingers. In this progress it furnishes an enve- lope to the extensor tendons, and is very much blended with the oblique fasciculi, by which they communicate with each other. The fascia brachialis affords origin, in part, to the mus- cles on the dorsum of the scapula below its spine; on the arm it is not so intimately connected with the muscles, but on the fore-arm they again begin to arise, in part, from it. In its whole course, partitions, constituting the sheaths of the muscles, and which consist, for the most part, of common cellular and adipose membrane, go from it down to the peri- osteum and interosseous ligament. It adheres very tightly to the ulna, from the olecranon to the styloid process. On its cutaneous surface are found all the superficial veins, nerves, and lymphatics of the arm. Bichat considers this mem- brane as the best example of the continuity of ligamentous with cellular tissue, and consequently of the affinity betweeti the two. The flexor tendons of the hand and fingers are held down, by the Ligamentum Carpi Volare or the Anterior Annular Ligament of the Wrist. It is a very strong fas- ciculus of ligamentous fibres, which subtends the concavity of the carpal bones in front, and converts it into the large oval foramen which contains the tendons. It is attached by one end at the ulnar side of the wrist, to the hook-like pro- cess of the unciforme; to the cuneiforme; and to the pisi- forme. Its fibres go straightly across the wrist to be at- tached by their other extremities to the radial end of the MUSCLES OF THE SHOULDER. 381 trapezium, and of the scaphoides. Its fibres may be readily distinguished from the fascia brachialis by their uniformly transverse course; by their wrhiteness; by their increased thickness; and by their great strength and unyielding nature. Yet the superior margin of this ligament is partially con- tinuous with the fascia brachialis, and the inferior margin with the aponeurosis palmaris. Several of the little muscles of the hand arise from its front surface, while the posterior is in contact with the flexor tendons. *# The Aponeurosis Palmaris is placed just below the skin, and covers the middle of the palm of the hand. Itis triangular and has its apex above, where it arises from the inferior margin of the volar or anterior annular ligament of the wrist, and from the tendon of the palmaris longus; it spreads out in its descent, and reaches the lower ends of the metacarpal bones, where it is divided into four portions. Each of these por- tions bifurcates and passes to the' head of its appropriate me- tacarpal bone, to be fixed to it just in advance of the anterior palmar ligament. The vacuity of the bifurcation permits the flexor tendons to pass on to the finger, and its branches are held together by transverse and reticulated fibres, the interstices of which are filled with fat. The lateral margins of this aponeurosis send off a thin membrane, for the purpose of covering the muscles of the thumb and of the little finger; or, in other words, the thenar and the hypothenar eminences in the palm of the hand. >ECT. IF.—OF THE MUSCLES OF THE SHOULDER- The Deltoidcs, _ Is a muscle which is extended over the top of the shoulder joint, and forms there the subcutaneous cushion of flesh which protects and gives rotundity to the articulation. It arises from the inferior edge of the whole spine of the scapula, from the circumference of the acromion process, and from the ex- terior third of the clavicle. Its origin, for the most part, is 382 MUSCLES tendinous and fleshy mixed, but at its posterior part it is en- tirely tendinous. It is inserted, by a tendinous point, into the triangular rough surface on the outer side of the os humeri near its mid- dle. Its general configuration is triangular, and, when spread out, its upper margin is much more extensive than one would suppose, as it is opposed to the entire insertion of the trapezius. Its fibres do not converge regularly to its in- sertion like the radii of a circle, but the whole muscle, is di- vided into several parts; .the interposition of intermuscular tendons iifto which, affecting the course of the fibres, makes several portions of (lie deltoid look penniform, and others like smaller deltoids introduced into the larger. The deltoid covers the insertion of the pectoralis major, latissimus dorsi, and teres major, besides that of the other muscles of the shoulder. It also conceals the origin of the biceps flexor cubiti and of the coraco brachialis. Its inser- tion is between the triceps extensor and the biceps flexor, and above the origin of the brachialis internus.* It raises the os humeri. Between the superior edge of the deltoid, the acromion process, and the subjacent tendons on the top of the articu- lation, there is a large Bursa Mucosa, which is sometimes partitioned off into two. The Supra Spindtus Scapulse, Arises fleshy from the whole fossa supra-spinata which it fills up, and from its margins. Forwards it terminates in a thick robust tendon closely connected with the capsular liga- ment of the joint, which passes under the jugum formed by the articulation of the acromion with the clavicle. It is inserted tendinous into the inner face of the great tu- berosity of the os humeri. It raises the arm and turns it outwards. „• ♦ * Varieties. Sometimes a fasciculus arises, between the infra-spinatus and the teres major, or from the inferior costa of the scapula, and joins itself to •lie deltoides. MUSCLES OF THL- SHOULDER. 383 The Infra-Spinatus Scapula;, Arises fleshy from all that portion of the dorsum scapula below its spine, from the spine as far as the cervix, and from the several margins of the fossa infra-spinata. Its fibres pass obliquely to a middle tendon, which adheres closely to the capsular ligament and goes under the projection of the acromion. This tendon is inserted into the middle facet of the greater tuberosity of the os humeri. The infra spinatus rolls the os humeri outwards and back- wards. There is a bursa between its tendon and the scapula. The Teres Minor,. Is situated at the inferior margin of the infra-spinatus, in the fossa of the inferior costa scapula, and looks very much like a part of the infra spinatus, to which it occasionally ad- heres so closely as to be separated with difficulty. It arises fleshy from the whole of the fossa, and the margins of the in- ferior costa, in the space from the cervix of the bone to with- in an inch or so of its angle. It is inserted tendinous and fleshy into the outer facet of the great tuberosity of the os humeri, just below the infra- spinatus. It draws the os humeri downwards and backwards, and rotates it outwrards. The Teres Major, Is situated at the inferior edge of the teres minor. It arises fleshy from the posterior surface of the angle of the scapula, and from a small part of its inferior costa; the interstice be- tween it and the teres minor is considerable. It is inserted, by a broad tendon, into the internal ridge of the groove of the os humeri, along with the tendon of the la- tissimus dorsi. Their tendons, at first, are closely united, but afterwards there is an intermediate cavity lubricated with 384 MUSCLES. synovia. The tendon of the latissimus dorsi is anterior, and the lower edge of the teres extends further down the arm than it. It rolls the humerus inwards, and draws it downwaids and backwards. The Subscapularis, Occupies all the thoracic surface of the scapula, being be- tween it and the se*rratus magnus. It arises fleshy from the whole base, superior and inferior costa, and costal surface of the scapula; it is divided into several columns, which look somewhat like distinct muscles, but they all terminate in a thick robust tendon that adheres to the inferior surface of the capsular ligament. This tendon is inserted into the lesser tubercle of the os humeri. The subscapularis rolls the bone inwards and draws it downwards. Between it and the neck of the scapula, there is a bursa which, as mentioned, communicates with the ar- ticulation. SECT. III.--OF THE MUSCLES OF THE ARM. The Biceps Flexor Cubiti. This muscle is situated immediately beneath the integu ments, and forms the swell so obvious in the middle front part of the arm. It arises by two heads. The first, called the long, is a round tendon which comes from the superior extremity of the glenoid cavity of the scapula, passes through the shoulder joint and through the groove of the os humeri; the second head arises tendinous from the ex- tremity of the coracoid process of the scapula, in company with the coraco-brachialis muscle. The fleshy bellies in which these tendons terminate, unite with each other, several inches below the shoulder joint, to form a common muscle. MUSCLES OF THE ARM. 385 At first they are only connected by loose cellular substance, but about half way down the arm they are inseparably united. The biceps terminates below in a flattened oval tendon, which passes in front of the elbow joint to be inserted into the posterior rough part of the tubercle of the radius. A bursa mucosa is placed between the tendon and the front of the tubercle, the surface of the latter being covered with car- tilage. From the ulnar side of this tendon proceeds an apo- neurosis running into that of the fore-arm. The relative position of the biceps is as follows : Its long head is first within the cavity of the capsular ligament, and then between the tendons of the latissimus dorsi and pecto- ralis major, where it is bound down by strong ligamentous fibres. The tendon below is superficial, and may be easily felt by flexing the extremity, but its insertion dips down be- tween the pronator teres and supinator radii longus. This muscle flexes the fore-arm.* The Coraco Brachialis, Is situated on the upper internal side of the arm, at the inner edge of the short head of the biceps muscle, with which it is connected for three or four inches. It arises tendinous and fleshy from the middle facet of the point of the coracoid process of the scapula, in common with the short head of the biceps muscle. It is inserted, tendinous and fleshy, into the internal side of the middle of the os humeri, by a rough ridge, just below the tendons of the latissimus dorsi and teres major, and in front of the brachialis externus. From the lower end of this muscle proceeds an intermuscular ligament to the internal condyle of the humerus, which separates the brachialis inter- nus from the third head of the triceps. • Varieties. Sometimes the division of the muscle is continued to the elbow; sometimes there is a third head coming either from the internal face of the os humeri, or from the brachialis internus; very rarely the number of heads has been multiplied to five, thereby making a close approximation to the arrangement in birds. This muscle h very liable to anomalies* VOL. I.—3 C 386 MUSCLES. This muscle draws the arm upwards and forwards.* The Brachialis Internus, Is situated immediately beneath the biceps and is concealed by it, excepting its outer edge. It has a bifurcated fleshy origin from the middle front face of the os humeri on each side of the insertion of the deltoid, and its origin is continued fleshy from this point downwards, from the whole front of the bone to within a very small distance of its articular sur- face. It is inserted, by a strong short tendon, into the rough surface at the root of the coronoid process of the ulna. A bursa sometimes exists between the tendon of the brachialis internus, that of the biceps, the supinator brevis, and the elbow joint. The brachialis flexes the fore-arm, and, by passing in front of the elbow joint, strengthens the latter very much. Its lower part lies under the tendon of the biceps, and between the pronator teres and the supinator longus.f The Triceps Extensor Cubiti, Forms the whole of the fleshy mass on the back of the arm; it therefore occupies the space between the integuments and the bone. It arises by three heads. The first, called Longus, comes, by a flattened tendon, between the teres major and minor muscles, from a rough ridge on the inferior edge of the cervix scapula. The second, called the Brevis, arises * Varieties. This muscle is almost always penetrated by the musculo-cuta- neous nerve; the perforation thus made sometimes exists as a fissure, extend. ing the length of the lower half of the muscle; on other occasions the fissure is so long as to divide the muscle completely into two. f Varieties. Sometimes, at its external margin, there exists a smaller bra- chialis internus muscle, which arises from about the same point of the hume- rus, and is inserted into the same part of the cubitus. Sometimes it detaches a fasciculus which joins the biceps muscle. Sometimes its posterior part is distinct from the anterior. Sometimes a fasciculus of it runs along the su- pinator longus of the fore-arm. MUSCLES OF THE ARM. 387 hy a sharp, tendinous, and fleshy beginning, from a slight ridge on the outer back part of the os humeri, just below its head. The third head, called Brachialis Externus, arises, by an acute fleshy beginning, from the inner side of the os humeri near the insertion of the teres major. This muscle, both at its external and internal edge, is separated from the muscles in front of the arm by the ligamentous septum, which arises near the middle of the os humeri and runs to its con- dyles. The whole back of the os humeri, as well as the pos- terior surface-of these intermuscular septa, is occupied by the origin of the triceps. The muscular fibres run in various directions, according to their respective heads and places of origin. At the inferior end of the muscle is found a broad tendon, which covers its posterior face. This tendon is inserted into the base or back part of the olecranon, and the ridge leading down the ulna on its radial side. The bellies of the triceps unite above the middle of the os humeri, but the interstices between them may be observed much lower down. There is a bursa between the tendon and the olecranon process; be- sides which, there is sometimes another on each side of the first. The triceps extends the fore-arm. The Anconeus, Is a small triangular muscle, just beneath the skin, at the outer posterior part of the elbow joint It arises tendinous from the posterior lower part of the external condyle of the os humeri, adheres to the capsular ligament of the joint, and is partly covered by the tendon of the triceps. It is inserted, fleshy and thin, into the ridge on the outer part of the head of the ulna leading from the olecranon, and .-fills up the triangular depression found there. It extends the fore-arm. 388 MUSCLES. SECT. IV.—OF THE MUSCLES OF THE FORE-ARM. There are eight muscles on the front of the fore-arm, some of which are superficial, and others deep seated. They for the most part are either directly or indirectly flexors of the fore-arm and hand. 1. The Pronator Radii Teres, Is just beneath the fascia of the fore-arm, and forms the radial side of the muscles of the internal condyle. It arises fleshy from the anterior face of the internal condyle of the humerus, and tendinous from the coronoid process of the ulna. It passes very obliquely across the fore-arm, at the internal edge of the brachialis internus muscle, and is insert- ed, tendinous and fleshy, into the external back part of the radius, just below7 the insertion of the supinator radii brevis, occupying about two inches of the middle of the bone. It rolls the hand inwards.* 2. The Flexor Manus vel Carpi Radialis, Is placed at the ulnar side of the last muscle, and is also superficial. It arises, by a narrow tendon, from the lower front part of the internal condyle of the humerus, fleshy from the intermuscular ligaments, fascia, and from the upper part of the ulna. It forms a thick fleshy belly, terminating below in a tendon, wrhich passes under the anterior annular liga- ment of the wrist, and runs through a groove in the os tra- pezium. It is inserted tendinous into the base of the metacarpal bone of the fore-finger, in front. There is a bursa between the lower extremity of its tendon and the trapezium ; the tendon is there held down by liga- mentous fibres. • Varieties. Sometimes it is double MUSCLES OF THE FORE-ATCM 3S9 It bends the hand, and draws it towards the radius. 3. The Palmaris Longus, Is at the ulnar side of the flexor carpi radialis, and is super- ficial. It is a small short muscle, terminating in a long slender tendon, and arises by a small tendon from the internal condyle, and fleshy from the intermuscular ligaments on each of its sides. It is inserted, tendinous, into the humeral margin of the ligamentum annulare anterius near the root of the thumb, and a division of its tendon passes on to the aponeurosis pal- maris. It bends the hand, and makes tense the palmar aponeu- rosis.* 4. The Flexor Manus vel Carpi Ulnaris, Occupies, among the superficial muscles, the ulnar side of the fore-arm. It arises, tendinous, from the internal con- dyle of the humerus, fleshy from the upper internal side of the olecranon, and, by a tendinous expansion, much connected with the fascia of the fore-arm, from the ridge at the internal side of the ulna to within three or four inches of the wrist. It is inserted into the humeral side of the os pisiforme by a round tendon, which arises high up at the radial margin of the muscle, and into which the muscular fibres run. Some- times the tendon is continued over the os pisiforme so as to be likewise inserted into the base of the metacarpal bone of the little finger. There is a loose bursa between the tendon and the pisiforme. It bends the hand, and draws it towards the ulna. 5. The Flexor Digitorum Sublimis Perforalus, Is concealed very much by the muscles just enumerated, * Varieties. Sometimes it is deficient in both arms; sometimes the middle part only is fleshy j sometimes the belly goes almost to the wrist. 390 MUSCLES. in consequence of being placed between them. To get a good view of its origin, they all should be cut away from the os humeri. It arises, tendinous and fleshy, from the internal Condyle of the os humeri, tendinous from the coronoid pro- cess of the ulna, and fleshy from the tubercle of the radius, the latter part of its origin being extended, tendinous obliquely, for three or four inches from that line of the radius which is at the lower margin of the pronator teres. With these ori- gins the muscle spreads over the front of the fore-arm at its upper part, from the radial to the ulnar margin. Four distinct tendons pass from the lower end of the muscle, which commence much above the wrist, pass beneath its an- terior ligament, and, having got to the palm of the hand, diverge to the several fingers. A tendon is appropriated to each finger, and passes in front of the metacarpal bone to the phalanges, being inserted, after having split into two, into the angles formed by the junction of the cylindrical and flat surfaces of the second phalanx, near its upper part. It bends the second phalanges on the first; its action may also be continued so as to clench the hand and to bend it on the fore-arm.* 6. The Flexor Digitorum Profundus Perforans, Is beneath the flexor sublimis and the flexor ulnaris. It arises fleshy from the oblong concavity of the ulna, between the coronoid and the olecranon processes, fleshy from the carpal margin of the base of the coronoid process, from the ulnar portion of the interosseous ligament, and from the front of the upper two-thirds of the ulna. The tendons of this muscle are different from those of the other; they commence in front of it, like a tendinous mem- brane, which is gradually divided into several fasciculi, * Varieties. The tendon to the little finger is sometimes wanting, in which case the deficiency is supplied by the tendon of the flexor profundus. Some- times the section of this muscle which belongs to the fore finger, is insulated from the rest of it, by a long fissure, and moreover divided by a middle ten- don, into two fleshy portions. MUSCLES OF THE FOREARM 391 adhering to each other by cellular membrane. The fascicu- lated character of the tendons is still preserved when they go under the anterior carpal ligament, and until they begin to disperse as distinct tendons to each of the fingers. Each tendon, going in front of its metacarpal bone and of the corresponding phalanges, gets through the slit in the flexor sublimis, and is inserted into the front part of the root of the third phalanx of its respective finger. It bends the last phalanges of the fingers, and may, by in- creased action, flex the hand like the preceding muscle.* 7. The F/exor Longus Pollicis, Lies in front of the radius, but beneath the flexor sublimis. It arises, by an acute fleshy beginning, from the radius just below its tubercle ; also fleshy from the middle two-thirds of the front of this bone, and from the radial portion of the in- terosseous ligament. The body of the muscle is joined by a small fleshy slip having a tendinous origin from the internal condyle of the humerus. A tendon is formed early on the ulnar margin of this muscle, to which the fibres pass obliquely. The tendon goes under the annular ligament of the wrist, through the fossa formed in the short flexor muscle of the thumb, and between the sesamoid bones, to be inserted into the base of the second phalanx of the thumb. From the inferior end of the fore-arm to the middle of the first phalanx, the tendon is invested by its appropriate bursa. It bends the last joint of the thumb. 8. The Pronator Quadratus, Is just above the carpal surfaces of the radius and ulna. * Varieties. Sometimes a distinct fasciculus comes from the internal con- dyle to join it; sometimes a fasciculus comes from the flexor longus pollicis, and terminating in a tendinous expansion, is inserted into the tendon wh'ch the flexor profundus sends to the fore finger 392 MUSCLES. and between the other muscles and the bone. In the adult it is about two inches wide, and its fibres run across the fore- arm. It arises fleshy and tendinous from the ridge at the inner surface of the ulna near its lower extremity, and from the front of the bone. It is inserted into the corresponding front surface of the radius. It rotates the radius inwrards.* The Flexor tendons of the fingers as they pass under the annular ligament are surrounded by the superior Bursa Mu- cosa, which begins about an inch and a half above the radio- carpal articulation, and extends to the lower margin of the annular ligament. It adheres externally to this ligament and to the capsule of the joint; internally it sends in a con- siderable number of processes whereby each tendon is sur- rounded, and connected to the adjoining tendons, while at the same time no restraint is put upon the natural motions of the part. In its texture this bursa resembles a dense and elastic cellular membrane. In addition to this bursa the flexor tendons as they pass from the root to the extremity of each finger are surrounded by a synovial bursa, which by its secretion continually lubri- cates them and permits them to play freely backwards and forwards according to the flexions and extensions of the fingers. These mucous sheaths begin a little distance above the first joint of the finger, adhere there to both flexor ten- dons, and extend to about the middle of the last phalanx. They give to the tendons a very polished lubricated surface; are reflected over the anterior flat faces of the phalanges, being separated from them by a small quantity of adipose matter; they are also reflected over the anterior faces of the capsular ligaments, and line the vaginal ligaments. The Vaginal Ligaments of the fingers (Ligamenta Vagi- nalia) bind down the flexor tendons and keep them applied to the fronts of the phalanges. They are of the same extent * Varieties. This muscle in some very rare cases does not exist. Some- times it consists in two layers whose fibres cross each other. In a case no- ticed in the Pennsylvania Hospital by Dr. J. R. Barton, it consisted in two triangular pieces, the bases of which were reversed. MUSCLES OF THE FORE-ARM. S9g from above downwards with the mucous sheaths just men- tioned, and arc stretched between the ulnar and the ra- dial margins of the phalanges. The fibres of which they consist pass for the most part transversely, and are of a fibro-cartilaginous character. These fibres diminish in num- ber from above downwards, and are stronger on the fore- finger than on any of the others. In front of the metacarpo- phalangial articulation, and the phalangial articulations, the vaginal ligaments are much thinner than elsewhere, in order to permit the free flexions of the fingers. The struc- ture, indeed, at these points is strongly marked off by its diminished thickness, and though the course of the fibres is the same from side to side, yet some anatomists have thought it worth while to designate it particularly, under the name of Annuli Juncturarum Ligamerttosi. Within the vaginal ligaments small tendinous frana arise from the first and second phalanges; they vary in number in different individuals, and run obliquely forwards, some to terminate in the flexor profundus tendons, and others in those of the flexor sublimis ; they are called Vincula Accessoria, and are covered by a reflection of the mucous membrane. Of the Muscles on the back of the Fore-arm. These muscles are ten in number. They arise, for the most part, from the external condyle, and the ridge leading to it, and are extensors either of the fore-arm, or of therfingers and thumb. Their origins are less blended with each other than those of the flexor muscles; nevertlieless, between several of them there are intermuscular ligaments which connect them closely. They are superficial and deep seated. 1. The Supinator Radii Longus, Is situated along the radial edge of the fore-arm, immedi- ately beneath the integuments. It arises, fleshy and tendi- nous, from the higher part of the ridge leading to the exter- nal condyle ; commencing just below the insertion of the vol. I.—3 D 394 MUSCLES. deltoid muscle, and being here placed between the brachialis internus and the short head of the triceps. It forms a thick fleshy belly, constituting the external margin of the arm, about the elbow joint; and terminates about the middle of the radius in a flat tendon. It is inserted, by the tendon, into a small, rough ridge, on the outer side of the radius just above its styloid process. It rolls the radius outwards. 2. The Extensor Carpi Radialis Longior, Is situated beneath the former muscle. It arises, tendi- nous and fleshy, from the space of the external ridge of the os humeri, between the supinator longus and the external condyle. It forms a short fleshy belly, which terminates in a flat tendon above the middle of the radius. It is inserted, by this tendon, into the posterior part of the root of the metacarpal bone of the fore-finger near the thumb. The tendon of this muscle is surrounded by a mucous sheath, at the place where it passes the lower end of the ra- dius, under the posterior carpal ligament. Another bursa is found, also, at its insertion, which, on one occasion, I found so much enlarged in a young woman, as to require its extir- pation, the operation was fully successful. It extends the hand.* 3. 'The Extensor Carpi Radialis Brevior. Is beneath the last, but projects somewhat beyond it. It arises, tendinous, from the posterior and lower part of the external condyle, and from the external lateral ligament of the elbow joint. It forms a thick, fleshy belly, placed along the radius, which terminates in a flat tendon about the mid- dle of that bone. Its tendon, becoming rounded, is inserted into the poste- * Varieties. Sometimes a small fasciculus is detached from its posterior margin, and has a tendinous insertion into the third metacarpal bone. MUSCLES OF THE FORE-ARM. 395 rior part of the base of the metacarpal bone of the second finger, and has a bursa beneath its insertion, and another at the wrist. It extends the hand.* 4. The Extensor Carpi Ulnaris, Is superficial, and placed principally parallel with the ulna. It arises, tendinous, from the external condyle, fleshy from the intermuscular ligament, and inside of the fascia. Cross- ing ve"ry obliquely the upper part of the radius and the ulna, it also arises fleshy from the back part of the latter bone. Its fibres terminate obliquely in a tendon which goes through the groove of the ulna, and is there furnished with a bursa. It is inserted, by its tendon, into the ulnar side of the base of the metacarpal bone of the little finger. It extends the hand.f 5. The Extensor Digitorum Communis, Is superficial, being placed between the extensor ulnaris and the extensor radialis brevior. It arises tendinous from the external condyle, and fleshy from the intermuscular liga- ment of the contiguous muscles. As it approaches the wrist it sends off four tendons, which pass together through a com- mon groove on the back of the radius. On the back of the hand these tendons diverge, and near the roots of the fingers send cross slips to each other. Each tendon goes to its respective finger and covers the whole posterior part of it, being spread out into a membrane which adheres to the phalanges from the root of the first to the root of the last. The section of this muscle appropriated to the little finger * Varieties. Sometimes this muscle is so blended with the preceding as to be in common with it f Varieties. Sometimes its tendon is joined, by a small fasciculus, to the extensor tendon of the little finger. 396 MUSCLE.*- has a distinct appearance, and sometimes its tendon goes through a distinct fossa in the the radius, from which causes it has obtained the name of Auricularis. A bursa invests these tendons at the wrist as they pass through their groove, and is single above; but, in follow ing the course of the tendons, like them it divides and follows each tendon respectively to the base of the first phalanx. This muscle extends all the joints of the fingers, being the antagonist of the flexors.* 6. The Supinator Radii Brevis, Can only be well seen by detaching the origins of the afore- said muscles ; it will then be found in contact with the radius, making a close investment of its head and upper third. It arises tendinous from the external condyle of the humerus, tendinous and fleshy from the ridge on the posterior radial edge of the ulna which descends from its coronoid process. Its fibres surround, obliquely, the upper external part of the radius, and are inserted into its tubercle, and into the oblique rough ridge corresponding with the upper margin of the pronator teres. At the interstice between the radius and ulna, near the anterior edge of this muscle, a fleshy slip is occasionally seen which passes from the radial side of the coronoid process to ihe ulnar edge of the radius. This muscle rotates the radius outwards.f 7. The Extensor Ossis Metacarpi Pollicis Mantis, Arises fleshy from the posterior part of the ulna immedi- ately below the anconeus, from the interosseous ligament, and from the back part of the radius just below the insertion of the supinator brevis. It terminates in a rounded tendon * Varieties. It sometimes sends a double tendon to the little finger, in which case the auricularis is more distinct than usual. f Varieties. Sometimes the superior part is separated from the inferior, sometimes the muscle is double. MUSCLES OF- THE FORE-ARM. 397 which passes over the tendons of the radial extensors, and through a groove on the styloid side of the lower end of the radius. The tendon is there invested by a bursa. It is inserted, by its tendon, into the base of the metacar- pal bone of the thumb and into the external side of the tra- pezium. It extends the metacarpal bone of the thumb. * 8. The Extensor Minor Pollicis Manus, Is at the ulnar side of the last muscle. It arises, tendi- nous, from the back of the ulna below its middle, and fleshy from the interosseous ligament. It adheres to the radius, and terminates in a tendon which passes through the groove in the styloid side of the radius, along with the last named muscle. It is inserted into the first phalanx of the thumb, by its tendon, which is extended to the root of the second phalanx. It extends the first phalanx, f 9. The Extensor Major Pollicis Manus, Arises, by a small tendinous and an extensive fleshy origin, from the back of the ulna above its middle, and from the in- terosseous ligament; it terminates near the wrist, in a ten- don which passes through a groove on the back of the radius near the ulna. The belly of this muscle conceals, very much, the other extensors of the thumb. It is inserted, by its tendon, into the oblong transverse tu- bercle, on the back of the base of the second phalanx of the thumb. Its tendon is furnished with one mucous sheath, at the inferior extremity of the radius, which extends to the * Varieties. This muscle is sometimes double, and has several other mo- difications which it is unnecessary to state. f Varieties. This muscle is sometimes only an appendage of the prece- ding. Occasionally its tendon is confounded with that of the succeeding muscle. 398 MUSCLES. carpus, and another which is smaller, and is placed upon the carpus and upon the base of the first metacarpal bone. It extends the second phalanx.* The tendons of the two last muscles are much connected with each other, and are spread in the form of a membrane on the back of the thumb, after the manner of the extensor tendons of the fingers. 10. The Indicator, Is a small muscle on the back of the ulna, concealed by the extensor communis and extensor ulnaris. It arises, tendi- nous and fleshy, from the back of the ulna, commencing near its middle, and from the contiguous part of the interosseous ligament. It terminates in a tendon which goes through the same fossa with the extensor communis; it afterwards is joined, about the head of the first phalanx, to the tendon of the common extensor belonging to the fore-finger. With the tendon of the extensor communis, it is inserted along the back of the fore-finger to the base of the third phalanx. It extends the fore-finger, f • Varieties. Sometimes this muscje is completely double. •J- Varieties. This muscle is subject to many modifications; sometimes it is digastric; sometimes it is double, and the second head goes to the mid- dle finger. In the latter case anatomists have recogniied a disposition simi- lar to that of the short extensor of the toes, and also an arrangement cor- responding with what occurs in some species of the ape. As a general rule it is admitted that the most of those varieties in the muscular system com- monly called anomalies, are only indications on the part of nature, of the alliance between the structure of man, and that of the lower orders of ani- mals. In this point of view Jhey are both instructive and amusing, and are well deserving of attention. MUSCLES OF THE HAND. 399 SECT. V.—OF THE MUSCLES OF THE HAND. The Palmaris Brevis, Is just below the skin, at the inner side of the hand. It consists of separate fasciculi unequally divided, and arises from the ligament of the wrist, and from the ulnar side of the palmar aponeurosis. It is inserted into the skin and fat at the inner margin of the hand, and covers the muscles of the little finger. It contracts the skin of the hand. Beneath the Aponeurosis Palmaris are placed the long flexor tendons and many of the, small muscles of the hand. The Lumbricales, Are conspicuous; they are four in number, of the size and shape of earth worms. They arise, tendinous and fleshy, from the radial sides of the tendons of the flexor profundus, beneath the ligamentum carpi annulare anterius, and a little beyond its inferior edge. They terminate in littje flat tendons, which run along the outer or radial edge of the fingers, and are inserted respec- tively into the tendinous expansion on the back of the first phalanx of each finger, about its middle. They bend the first phalanges.* Four muscles constitute the ball of the thumb. 1. The Abductor Pollicis Manus, Arises, tendinous and fleshy, from the anterior surface of * Varieties. Sometimes one is deficient; sometimes one or more is double, in which case the supernumerary goes to the ulnar edge of the ad- joining finger. 400 MUSCLES. the ligamentum carpi annulare, and from the projecting ends of the trapezium and scaphoides. It is inserted, tendinous, into the outer side of the base of the first phalanx of the thumb, and into the tendinous mem- brane derived from the extensors on its bark part. It draws the thumb from, the fore fingers. This muscle is next to the skin. 2. The Opponens Pollicis, Is beneath the abductor, and without its removal can scarcely be seen. It arises, tendinous and fleshy, from the projecting point of the os trapezium, and from the adjacent part of the angular ligament. . It is inserted, tendinous and fleshy, into the radial edge of the metacarpal bone of the thumb, from its base to its head. It draws the metacarpal bone inwards. 3. The Flexor Brevis Pollicis Manns, Is beneath the abductor pollicis, and at the side of the op- ponens pollicis. A groove is formed in it by the tendon of the flexor longus pollicis, which divides it into two heads. The first head arises, fleshy, from the points of the trape- zoides, trapezium, and from the contiguous part of the inter- nal surface of the annular ligament, and is inserted into the outer sesamoid bone; the sesamoid bone, like a patella, being connected to the first phalanx of the thumb by a tendon. The second or internal head arises, fleshy, from near the metacarpal surfaces of the,magnum and unciforme, and from the base of the metacarpal bone of the middle finger. It is inserted into the inner sesamoid bone, which, like the external, is connected, by ligament, to the first phalanx. The short flexor, as its name implies, bends the first pha- lanx of the thumb. MUSCLES OF THE HAND. 401 4. The Adductor Pollicis Manus, Lies in the palm of the hand, beneath the lumbricales and the tendons of the flexor sublimis and profundus. It arises, fleshy, from the ulnar edge of the metacarpal bone of the se- cond finger, between its base and head. It is inserted, ten- dinous, into the inner part of the base of the first phalanx of the thumb, just above the sesamoid bone. It pulls the thumb towards the fingers. The Abductor Indicis Manus, Is on the radial edge of the hand, between the metacarpal bones of the fore-finger and thumb, and is just beneath the skin. It arises tendinous from the trapezium, and fleshy from the ulnar edge of the metacarpal bone of the thumb, between its base and head. Being placed along the side of the metacarpal bone of the fore-finger, it is inserted, by a short tendon, into the radial side of the first phalanx. It draws the fore-finger from the others. There are three muscles constituting the ball of the ulnar side of the hand or of the little finger. 1. The Abductor Minimi Digiti Manus, Is the most superficial. It arises, fleshy, from the protu- berance on the internal side of the os pisiforme, and from the contiguous parts of the annular ligament. It is inserted, tendinous, into the ulnar side of the first phalanx of the little finger, and into the tendinous membrane which covers its back part. It draws the little finger from the rest. 2. The Flexor Parvus Minimi Digiti Manus, Is beneath the abductor. It arises, fleshy, from the unci- vol. i.—3 E 402 MUSCLES form process of the os unciforme, and from the contiguous parts of the annular ligament. It is inserted, tendinous, into the ulnar side of the base of the first phalanx of the little finger, being united with the tendon of the abductor, and with the tendinous membrane expanded over the back of the finger. It bends the little finger.* The Adductor Metacarpi Minimi Digiti, Is placed beneath the Abductor and Flexor, next to the metacarpal bone. It arises, fleshy, /rom the unciform pro- cess of the os unciforme, and from the contiguous part of the annular ligament of the wrist. It is inserted, tendinous and fleshy, into the fore part of the metacarpal bone of the little finger, from its base to its head. It brings the metacarpal bone of the little finger towards the wrist, and thereby deepens the hollow of the hand. The Interosseous Muscles fill up the interstices of the me- tacarpal bones ; they arc seven in number, four on the palm, and three on the back of the hand. The back ones arise by double heads from the contiguous sides of two metacarpal bones ; the inner ones have a single head, which comes only from the metacarpal bone of the finger which such interos- seous muscle is intended to serve. As a general description they all may be said to arise, fleshy and tendinous, from the base and sides of the metacarpal bones, and to be inserted, tendinous, into the sides of the first phalanges, and into the tendinous membrane on the back of the fingers, derived from the tendons of the extensor communis. The four first must be looked for on the palm, the three others on the back of the hand. * Varieties. Sometimes it is wanting, in which case, the preceding is more leveloped than usual. MUSCLES OF THE HAND 403 1. The Prior Indicis, Is along the radial side of the first metacarpal bone, and arises from the base and side of the same. It is inserted, tendinous, into the radial side of the first phalanx. It draws the fore-finger towards the thumb. 2. The Posterior Indicis, Is at the ulnar side of the first metacarpal bone. It arises from the base and ulnar side of the same bone, and is insert- ed, tendinous, into the ulnar side of the first phalanx of the fore-finger. It draws the fore-finger towards the others. 3. The Prior Annularis, Is at the radial side of the metacarpal bone of the third or ring finger. It arises from the base and radial side of the -said bone. It is inserted, tendinous, into the radial side of the first phalanx of the ring finger. It draws that finger towards the thumb. 4. The Interosseus Digiti Auricularis, Is at the radial side of the metacarpal bone of the little finger. It arises from the radial side and base of said bone. It is inserted, tendinous, into the radial side of the first phalanx of the same finger. It draws the little finger towards the others. By removing the tendons of the extensor communis from the back of the hand, we see the three posterior or double- headed interosseous muscles. 404 MUSCLES. 5. The Prior Medii. Is between the metacarpal bones of the fore and of the mid- dle finger. It arises from the opposed roots and sides of these bones. It is inserted, tendinous, into the radial side of the first phalanx of the middle finger. It draws the middle finger to- wards the thumb. 6. The Posterior Medii, Is between the metacarpal bone of the middle and of the ring finger. It arises from the opposite sides and roots of these bones. It is inserted, tendinous, into the ulnar side of the first phalanx of the middle finger. It draws the middle finger towards the little. 7. The Posterior Annularis, Is between the metacarpal bones of the ring and little finger. It arises from the opposed sides and roots of these metacarpal bones. It is inserted, tendinous, into the ulnar side of the first phalanx of the ring finger. It draws the middle towards the little finger. FASCIA OF LOWER EXTREMITY. 405 CHAPTER IV. OF THE FASCIA AND MUSCLES OF THE LOWER EX- TREMITIES. SECT. I.—OF THE FASCIA. The muscles of the lower extremity, from the pelvis to the foot inclusively, are invested by a strong aponeurotic mem- brane, placed immediately beneath the skin or common in- teguments. Its external face is in contact with the superfi- cial nerves and blood-vessels, and the internal face with the muscles. Though it is absolutely continuous from one end to the other, it will be useful, for study, to divide it into three parts; the one covering the thigh, the second covering the leg, and the third covering the foot; as each of them presents certain points of arrangement, which could not be very con- veniently introduced into a general description. 1. The aponeurosis of the thigh {Fascia Lata Femoris) be- gins posteriorly, from the upper part of the gluteus maximus muscle, by a very gradual conversion of the cellular mem- brane of the part into desmoid substance; it also begins in the way of cellular substance from the margins of the sacrum and os coccygis. The character here is seldom clearly aponeu- rotic till it gets on a level with the tendon of the gluteus max- imus, from which emanate a great many of its fibres. Exter- nally, it arises from the whole length of the crista of the ilium, is there strikingly aponeurotic, and is closely adherent to the gluteus medius muscle, many of whose fibres arise from it. It also arises from the body and descending ramus of the pubes, and from the tuber and ascending ramus of the is- chium. Its attachment at the latter is not very strong, nei- ther is its character so well marked. It is there, in some measure, continuous with the pectineal fascia. In front, it adheres very closely to the inferior margin of the tendon ot 406 MUSCLES. the external oblique muscle, so as to be almost continuous with it, from the anterior superior spinous process of the ilium to the pubes. From these several connexions at the pelvis, the fascia fe- moris descends in enveloping the muscles of the thigh, and then forms other strong attachments about the knee, to the condyles of the os femoris and to the bead of the tibia. In front, it adheres very closely to, and is almost blended into the common tendon of the extensor muscles; it adheres also to the inferior margins of the two vasti, and is nearly one and the same ; with the membranous expansion going from them to the head of the tibia, and answering the purpose of capsu- lar ligament to the articulation of the knee, on each side of the patella, as far back as the lateral ligaments. Behind, it covers up the fat in the ham, and is continued into the fascia of the leg. This fascia, almost every where, consists in a fibrous tex- ture wliich is sufficiently evident, but the fibres pass in very various directions. At many places, particularly on the in- ternal side of the thigh, there are oblique fibres spread upon a lamina which is not fibrous. On the outside of the thigh, the fascia consists principally in longitudinal fibres held to- gether by transverse ones; and when its muscular surface is examined, many oblique fibres are also found there. It is very thick and strong externally, thinner behind, and still weaker internally, where cellular substance seems to predo- minate in its composition. It is pierced at several points with small round holes for the passing of blood-vessels and of the cutaneous nerves. From the interior surface of the Fascia Femoris, partitions pass off, which separate the muscles of the thigh from each other, and form sheaths for them. Some of these processes are merely cellular substance; others have a more distinct desmoid character. Externally, as it passes from the glu- teus medius to the groin, it separates into two lamina?, which receive between them the tensor vagina femoris, and then re-unite. The sartorius muscle, in almost its whole length, is also enclosed between two lamina. At the origin of this FASCIA OF LOWER EXTREMITY. 407 muscle, its posterior lamina passes on to the iliacus internus and psoas magnus muscles, and then to the pectineus, in all of which distance it is continuous with the iliac fascia of the pelvis; the anterior lamina of the sartorial fascia has its up- per margin continuous with Poupart's ligament, and termi- nating in a point or angle, which is turned inward towards the crista of the pubes, not far from its spine. The point it- self is not inserted into the crista of the pubes, but into the pectineal portion of the fascia lata just below it. This point, from the part which, it plays in femoral hernia, has been stu- died with particular attention, and goes under the name of Hey's, or the Femoral Ligament. The posterior lamina of the sartorial fascia is placed be- hind the femoral vessels, but the anterior lamina is before them. The latter terminates on its pubic side, in a crescen- tic or lunated edge of one and a half or two inches in length, the concavity of which is towards the penis.* Hey's liga- ment is the superior extremity of the crescent; the inferior end can scarcely be considered to have a definite boundary, but is continuous with the adjacent part of the fascia lata. The place of continuity is covered by the saphena vein, which being between the skin and the fascia lata, dips there into the femoral vein which is below the fascia lata. The femo- ral vessels reposing in their sheaths, are then placed between these two laminfie of the sartorial fascia. The vein is only partially covered by the lunated edge, while the artery, which is on the iliac side of the vein, is completely concealed. By keeping the leg extended, and turning the toes of the subject inwards or outwards, it will be seen that the fascia lata and the tendon of the external oblique exercise a mutual tension. Beneath Poupart's ligament, at the inner margin of the fe- moral vein, is the hole called Femoral Ring, through which the bowel escapes in femoral hernia. This hole is constrict- ed by turning the toes outwards, and relaxed by turning them * The crescentic edge is not always well defined, for in many cases it is blended insensibly with the sheath of the vessels, so that a defined exhibi- tion of it is rather the result of artificial separation or dissection, than a natu- ral condition. 408 MUSCLKb. inwards: it becomes very much relaxed if, at the same time, the thigh be drawn upwards. Valuable indications for the mode of replacing a prolapsed bowel are thus obtained. In addition to this arrangement, which is all important in hernia, the fascia femoris has the following. On the front of the thigh it simply covers the extensor muscles, the parti- tions between which are cellular substance. On the inner side it dips down to the periosteum between the adductor muscles, but is still cellular. Behind it covers the hamstring muscles, and sends down to the linea aspera a thick fibrous partition between the vastus externus and the biceps flexor. The superior margin of the gluteus maximus is inserted into this fascia, which from its connexion with the gluteus medius and tensor vaginae femoris, causes all these muscles to exer- cise a mutual influence, as well as to keep tense the fascia itself. On the internal semi-circumference of the thigh it adheres somewhat closely to the muscles, but on the external, where the fascia is opposed to the tendinous facing of the vastus externus muscle, it is connected by a long, loose, and scattered cellular substance, which scarcely presents an ob- stacle to the introduction of the finger or any blunt instru- ment between the two. 2. The Fascia Cruralis, or that of the Leg, though abso- lutely continuous with that of the thigh, may be described as arising externally, from the head of the fibula and from a prolongation of the biceps flexor cruris; internally, from pro- longations of the tendons of the sartorius, the gracilis, and the semi-tendinosus. It in descending covers all the super- ficial muscles of the leg, does not go over the tibia, but ad- heres to its spine and to its internal angle. It unites below to the annular ligament of the ankle, to the ligamentous sheath of the peroneal muscles, and to that on the inner ankle. The fascia cruralis, in the superior half of the leg, assists in giving origin to its muscles in front and externally, but is rather loosely attached to them below. On the back of the leg it is also rather loosely connected to the gastroc- FASCIA OF LOWER EXTREMITY. 409 nemii. It sends in one aponeurotic partition between the common extensor of the toes and the long peroneus, and another between the latter and the soleus, both of which are inserted into the fibula. It also is insinuated between the soleus and the flexor muscles next to the bones. This pro- longation is strong and fibrous, penetrates between these flexor muscles, dips down to the tibia and fibula, and is lost insensibly just below the fascia of the popliteus muscle. This last fascia may also be considered one of the emanations from the fascia cruralis. The fascia cruralis is not so strong as the femoral, yet it has the same compact desmoid texture, and is formed from fibres crossing in various directions. It is thicker in front than behind, and is made tense by its connexion with the internal and external hamstring muscles. Of the Ligamentum Annulare of the Ankle Joint. The muscles on the front of the leg have their tendons con- fined at the ankle by this ligament, which may be very pro- perly associated with the description of the crural fascia, owing to the closeness of their connexion. It consists in a fasciculus of ligamentous fibres running across the front of the ankle joint It is attached by one extremity to the supe- rior face of the os calcis just before the malleolus externus; is there very strikingly fibrous or ligamentous, and has its Tsmall fasciculi separated by fatty matter. It is then directed inwards, and divides into two laminae, one of which goes above the tendons, and the other below them. These laminae by adhering to their respective sides of the tendons form a loose gutter for each of them to play in ; the gutters, however, for the tibialis anticus and extensor pollicis are not so perfect behind as the others, and are also more loose. The ligament is then fixed by one division to the anterior margin of the malleolus internus, and by another, which is wrapped over the internal face of the foot, into the scaphoides and the in- ternal margin of the fascia plantaris. As the upper margin VOL. I.—3 I 410 MUSCLES. of this ligament is continuous with the fascia cruralis, so the inferior runs into the fascia on the back of the foot. 3. Of the Fascial of the Foot.—The fascia cruralis, being strongly attached to the posterior and lower margins of the internal ankle, its fibres radiate thence to the lower part of the tendo achillis, to the inner side of the os calcis, and to the internal margin of the fascia plantaris. This is the Liga- mentum Lacineatum of writers, and conceals the tendons which pass to the sole of the foot along the sinuosity of the os calcis. The Aponeurosis Dorsalis is continued from the annular ligament, over the upper surface of the foot, to the roots of the toes. It is thin, but its fibrous texture is apparent. It is spread over the extensor tendons of the toes and the ex- tensor brevis muscle, and is slighty attached along the in- ternal and the external margin of the foot The Aponeurosis Plantaris is on the sole of the foot, be- tween its common integuments and the muscles. It is attached behind to the tuberosities of the os calcis, and is quickly di- vided into three portions, which are kept distinct by well marked depressions between them. The internal portion lies upon the muscles at the inner side of the foot, the ex- ternal portion upon the muscles at the outer side, and the middle covers longitudinally the central parts of the sole. The two first portions are thin, reticulated, and extend to the roots of the outer and inner metatarsal bones ; and along the margins of the foot, where they join the fascia dorsalis. The middle portion increases in breadth as it advances, and at the anterior extremity of the metatarsus is divided into five slips, one for each metatarsal bone. Each of these slips is subdivided into two, which penetrate upwards, and fix themselves to their respective side of the head «f the meta- tarsal bone. In the interval left by this bifurcation, pass the flexor tendons, the lumbricales, the vessels and the nerves, to the toe. MUSCLES OF THE THIGH. 411 The plantar aponeurosis, or fascia, affords behind origin to the superficial muscles of the foot It also sends in par- titions between them. Its thickness is considerable behind, but continually diminishes as it advances forwards. Its fibrous texture is very well marked, and is much more com- pact near the heel, where it looks like ligament; the fibres run principally longitudinally. From its inferior surface many strong filaments pass to the skin on the sole of the foot, and contain within their interstices a granulated adeps. SECT. II.--MUSCLES OF THE THIGH. The Tensor Fascias vel Vaginas Femoris, Is situated superficially on the anterior outer part of the hip. It arises tendinous from the anterior superior spinous process of the ilium ; passes downwards and somewhat back- wards between two laminae of the fascia femoris, increasing in breadth as it descends; and is inserted fleshy into the in- terior face of the fascia femoris, somewhat below the level of the trochanter major. It rotates the foot inwards, and makes the fascia tense. The Sartorius, Is placed superficially on the internal side of the thigh. It arises by a short tendon from the anterior superior spi- nous process of the ilium, and passes in a spiral course to the inner side of the thigh and to the back of the internal condyle. It then winds behind the head of the tibia, and ad- vances forwards, so as to be inserted into the internal side of the lower part of its tubercle by a broad tendon. Its fibres run the whole length of the muscle. Its tendon is continued by a flat slip from its lower mar- gin into the fascia cruralis, by which attachment the muscle is held in its spiral course. It crosses the rectus femoris and vastus internus above, the triceps adductor at the middle of m MUSCLES. the thigh, and at the lower part of the latter, just abo\e the knee, it is between the tendon of the adductor magnus and that of the gracilis. It bends the leg and draws it obliquely inwards.* The Rectus Femo?is, Is in front of the thigh bone and just beneath the fascia fe- moris, with the exception of its origin, which is covered by the sartorius. It is a complete penniform muscle, fleshy in front for the most part, but faced behind with tendon. It arises, from the anterior inferior spinous process, by a round tendon, which is joined by another tendon coming from the superior margin of the acetabulum. It is inserted into the superior surface of the patella by a strong tendon, and intermediately by the ligamentum patella* into the tubercle of the tibia. It extends the leg. The Vastus Externus, Is a very large muscle on the outside of the thigh; it arises,. tendinous and fleshy, from the upper part of the os femoris, immediately below the trochanter major. Its origin com- mences in front and passes obliquely around the bone to the linea aspera. It continues afterwards to arise from the whole length of the linea aspera, and from the upper half of the line running from it to the external condyle. Its fibres pass inwards and downwards, and are inserted, by a flat tendon, into the external edge of the tendon of the rectus, and also into the external upper part of the patella. This muscle has a broad tendinous surface exteriorly and * Varieties. Sometimes a small fasciculus is detached from its inferior part; sometimes its fibres are interrupted by a mi-idle tendon which ad- heres closely to the fascia femoris. Meckel reports it as deficient in one: case that he met with. In the African I have occasionally seen it unusuallj broad. MUSCLES OF THE THIGH.* 413 above; at its lower part it has a tendinous facing on the side next to the bone. It also extends the leg. The Vastus Internus, Covers the whole inside of the os femoris. It arises, by a pointed fleshy origin, in front of the os femoris, just on a level with the trochanter minor; tendinous and fleshy from the whole length of the internal edge of the linea aspera, and from the line leading from it to the internal condyle. Its fibres descend obliquely, and are inserted by a flat ten- don into the internal edge of the tendon of the rectus, and into the upper internal edge of the patella. It also extends the leg. The Crurxus, Is almost completely overlapped and concealed by the two vasti, and is immediately behind the rectus femoris. The edge of the vastus externus above is very distinguishable from it, as it overlaps it, and is rounded off, besides being some- what separated by vessels. But the origin of the vastus in ternus is not so distinguishable, as the fibres of the two mus- cles run into each other ; it is therefore necessary most fre- quently to cut through some of the fibres on the internal face of the os femoris, on a level with the trochanter minor. The cruraeus will then be seen to arise, fleshy, from all the fore part of the bone, and from all its outside as far as the linea aspera. Between the internal edge of this muscle and the linea aspera, the interior face of the os femoris is naked the breadth of an inch along the whole shaft of the bone, which is very, readily seen by turning off the vastus internus. The cruraeus is inserted into the posterior face of the ten- don of the rectus below, and into the upper surface of the pa- tella. It also extends the leg. The Ligamentum Patellae is the common chord by which 414 ' MUSCLES. ■ the action of the four last named muscles is communicated to the tibia. It is a flattened thick tendon an inch and a half wide, arising from the inferior edge of the patella, and in- serted into the tubercle of the tibia. Between its insertion and the head of the tibia is a bursa. Besides this a fascia or tendinous expansion, an appurtenance of the fascia femoris as mentioned elsewhere, comes from the inferior ends of these muscles; extends itself over the whole of the anterior and lateral parts of the knee joint; and is inserted into the head of the tibia and of the fibula. Through this it happens that even when the patella or its tendon is fractured, some mo- tion or extension may be communicated to the leg from the thigh. In consequence of the common insertion of these four mus- cles, some anatomists describe them as but one, under the name of Quadriceps Femoris.* A subcutaneous bursa exists between the lower part of their tendon and the fascia femoris; occasionally one is found still lower down, on the patella. Some unimportant varieties have been observed, The Gracilis, Is a beautiful muscle at the inner margin of the thigh, and lies immediately under the fascia; it extends from the pelvis to the leg. It arises, by a broad thin tendon, from the front of the os pubis, just at the lower part of its symphysis, and from its descending ramus; the muscle tapers to a point below, and a little above the knee terminates in a round tendon, which passes behind the internal condyle of the os femoris and the head of the tibia. It then makes a curve forwards and down- wards at the internal side of the latter, and is inserted at the lateral and inferior part of its tubercle. The tendon at the knee is beneath the tendon of the sarto- rius. This muscle is a flexor of the leg. * Soemmering de Corp. Hum Fal. MUSCLES OF THE THIGH. 415 The Pectinalis, Is a short fleshy muscle at the inner edge of the psoas mag- nus. It arises, fleshy, from the concavity on the upper face of the pubes, between the linea innominata and the ridge above the obturator foramen, and is inserted, tendinous, into the linea aspera immediately below the trochanter minor. It draws the thigh inwards and forwards.* Adductors. 1. The Adductor Longus comes, by a rounded short ten- don, from the upper front part of the pubes near its symphi- sis; it forms a triangular belly which increases in breadth in its descent, and is inserted into the middle third of the Knea aspera at its inner edge. This muscle, as the subject lies on its back,is uppermost; its origin is between that of the pectinalis and of the gracilis, its upper edge is in contact with the lower edge of the pecti- nalis. f 2. The Adductor Brevis is the smallest of the three; it is situated beneath the adductor longus and pectinalis, and on the outside of the gracilis. It arises, by a rounded tendon, from the middle front part of the pubes, between its symphisis and the foramen thyroideum, just below the origin of the first adductor. It is inserted into the tipper third of the inner edge of the linea aspera, between the trochanter minor and the upper edge of the adductor longus, by a flat thin tendon. \ * Varieties. Sometimes this muscle is split into two by a fissure, in whicl; case the lower portion is the smaller, and has its tendon below connected or joined to the tendon of the other, and its other extremity attached to the upper internal margin of the thyroid foramen. f Varieties. Occasionally this muscle is divided into two by a fissure, which is of various lengths. Sometimes it is continued much lower down than usual by means of a small tendon united to that of the adductor magnus. % Varieties. It also is occa#onally split, more or less fully, into two mus- cles by a fissure, which, according to Meckel, establishes a remarkable ana- Jogy wKh apes. lit) MUSCLES. S. The Adductor Magnus is below7 the other two, and is by far the largest. It arises, fleshy, from the lower part of the body of the pubes and from its descending ramus, also from the ascending ramus of the ischium as far as its tube- rosity, occupying the whole bony surface between the fora- men thyroideum below, and the margin of the pelvis. It is inserted, fleshy, the whole length of the linea aspera, and on its internal margin a tendon is gradually generated which passes downwards to be inserted into the upper part of the internal condyle of the os femoris, and, by a thin edge or expansion, into the line leading from the linea aspera to the internal condyle. The adductor magnus separates the muscles on the ante- rior from such as are on the posterior part of the thigh; and its insertion is closely connected with the origin of the vas- tus internus, the two surfaces adhering by a short and com- pact cellular membrane.* The three adductors contribute to the same end, that of drawing the thigh inwards. From their common action and very close connexion at their insertions, they are sometimes described as one, under the name of Triceps Adductor, and with great propriety. The pectineus muscle is also asso- ciated with them so closely in its course and character, that as Meckel has suggested, it ought to be considered as a fourth head to the triceps. The Glutseus Magnus, Arises, fleshy, from the posterior third of the spine of the ilium, from the side of the sacrum below it from the side of the os coccygis, and from the posterior surface of the large sacro-sciatic ligament. The fibres of this muscle are col- lected into large fasciculi with deep interstices between them; and the lower edge of it is folded over the sciatic ligament. Its fibres pass obliquely forwards and downwards, and terminate in a thick broad tendon, the upper part of which * Varieties. It is also occasionally divided into two portions as in apes. MUSCLES OF THE THIGH. 417 goes on the outside of the trochanter major, and is very strongly inserted into the fascia femoris; w hile the lower part is inserted into the upper third of the linea aspera, going down as far as the origin of the short head of the biceps flexor cruris. This muscle is placed immediately under the skin, the fas- ciculi being separated to some depth by processes from the fascia femoris. It covers nearly all the other muscles on the back part of the pelvis, laps over its inferior margin lateral- ly, and conceals the origins of the hamstring muscles. There is a very large bursa placed between the tendon of this muscle and the external face of the trochanter major; another of almost equal magnitude, between it, the superior extremity of the vastus externus, and the inferior end of the tensor fasciae femoris ; and there are two still smaller between the same tendon and the os femoris, which are placed lower and more posteriorly. The gluteus maximus draws the thigh backwards and as- sists in keeping the trunk erect. The Glutaeus Medius, Arises from the whole length of the spine of the ilium, ex- cept its posterior part, and from that part of the dorsum of the bone which is between its spine and a semicircular ridge extending from the anterior superior spinous process to the sciatic notch; also from the lunated edge of the os ilium be- tween the anterior superior and anterior inferior spinous processes, and from that part of the inner face of the fascia femoris which covers it. The anterior superior part of this muscle is not covered by the gluteus magnus, but lies before it. Its fibres converge, and are inserted, by a broad thick tendon, into the upper surface of the trochanter major, and into the upper anterior part of the shaft of the bone just in front of the trochanter. It draws the thigh backwards and outwards. A bursa is interposed between the extremity of its tendon and the tendinous insertions of the small rotator muscles. . vol. i.—3 G 418 MUSCLES. The Glutaeus Minimus, Arises from that part of the dorsum of the ilium between the semicircular ridge just spoken of, and the margin of the capsular ligament of the hip joint. It is entirely concealed by the gluteus medius. Its fibres converge and terminate in a round tendon, which is inserted into the anterior superior part of the trochan- ter major, just within the anterior insertion of the gluteus medius. It abducts the thigh, and can also rotate the limb inwards. A bursa of small size exists between its tendon and the tro- chanter major. There are several small muscles about the hip joint, the most of which can be seen by the removal of the gluteus magnus. The Pyriformis, Arises, fleshy and tendinous, within the pelvis, from the anterior face of the second, third, and fourth bones of the sa- crum. It forms a conical belly which passes out of the pel- vis at the upper part of the sacro-sciatic foramen, receiving a slip of fibres from the posterior inferior spinous process of the ilium. It is inserted, by a round tendon, into the upper middle part of the trochanter major within the insertion of the glu- teus medius. It rotates the limb outwards. Between its tendon and the superior geminus a small bursa exists.* The Gemini, Are two small muscles, closely connected with each other. which are situated lower down on the limb than the pyri- * Varieties, it is sometimes split by the sciatic nerve, and when the latter divides very high up, by one of its portions only. MUSCLES OF THE THIGH. 419 formis. The upper one arises from the posterior part of the root of the spinous process of the ischium; the lower from the upper back part of the tuberosity of the ischium. Being parallel to each other, and connected by their con- tiguous edges, they are inserted together into the posterior part of the thigh bone at the root of the trochanter majoc where the deep cavity is. They also rotate the limb outwards.* The Obturator Internus, Is principally situated within the cavity of the pelvis. It arises, fleshy, from all the pelvic margin of the foramen thy- roideum, except where the obturator vessels go out, and from the internal face of the ligamentous membrane stretched across it; also, from the upper part of the plane of the ischium just below the linea innominate.; its fibres con- verge, and, forming a tendon, pass out of the pelvis over the trochlea of the ischium, between the sacro-sciatic ligaments. The tendon is placed between the gemini muscles, which form a sheath for it; and it is inserted into the pit on the back of the os femoris, at the root of the trochanter major. Between the tendon of this muscle and the gemini is a long bursa; a second is found where the muscle plays over the ischium. It rotates the limb outwards. The Quadratus Femoris, Is lower down than the other muscles. It arises, tendinous and fleshy, on the outer side of the ischium, from the ridge which constitutes the exterior boundary of the tuberosity. Its fibres are transverse, and are inserted, fleshy, into the rough ridge of the os femoris, on its back part, which goes from one trochanter to the other. * Varieties. The upper one occasionally does not exist, whereby a strik- ing resemblance with apes is established. Sometimes both are wanting. 420 MUSCLES. It rotates the limb outwards. A bursa exists between it and the trochanter minor.* The Obturator Externus, Is concealed, in front, by the pectineus and triceps adduc- tor, and behind by the quadratus femoris; to get a satisfac- tory view of it, therefore, these muscles should be detached from the bone. It arises from the whole exterior circumfe- rence of the foramen thyroideum, excepting the place where the obturator vessels come out, and from the exterior face of the ligamentous membrane stretched across it. The fibres of this muscle converge, pass beneath the cap- sular ligament of the hip joint adhering to it, and terminate successively in a round tendon, which is inserted into the in- ferior part of the cavity on the posterior surface of the os femoris, at the root of the trochanter major. The course of the tendon of this muscle is marked on the neck of the thigh bone by a superficial fossa. It rotates the thigh outwards. The Biceps Flexor Cruris, Constitutes the outer hamstring, and is situated on the pos- terior outer part of the thigh ; it arises by two heads. The first, calleu the long head, has an origin, in common with the semitendinosus, from the upper back part of the tuberosity of the ischium, by a short tendinous head, which, in its descent, is changed into a thick fleshy belly. The other, called the short head, arises, by an acute fleshy beginning, from the linea aspera just below the insertion of the gluteus magnus, and is continued along the lower part of the linea aspera from the ridge leading to the external condyle. A thick tendon is gradually formed on the outside of the muscle, which, descending along the external faceof the ex- * Varieties. Occasionally this muscle is absent; more rarely it is divided into a great number of fasciculi, amounting in one instance to thirty. MUSCLES OF THE THIGH. 421 ternal condyle, is inserted into the superior face of the head of the fibula. A bursa is found between this tendon and the external lateral ligament of the knee. This muscle flexes the leg on the thigh.* The Semitendinosus, * Is on the inside of the thigh, between the biceps and gra- cilis ; it is superficial, being immediately under the fascia, and arises, in common w ith the biceps, from the back part of the tuberosity of the ischium ; it also adheres, for three or four inches, to the inner edge of the tendon of the long head of the biceps. About four inches above the knee it terminates in a long round tendon, which passes behind the internal condyle and the head of the tibia, and is reflected forwards to be inserted into the side of the tibia, just below its tubercle and very near it, being lower down than the insertion of the tendon of the gracilis. Its insertion is much connected with that of the gracilis, and is generally divided into two slips, one above the other. Between its origin, that of the long head of the biceps, and the semimembranosus, there is a bursa ; one or more are likewise found between its tendon below, that of the sartorius, of the gracilis, and the internal lateral ligament of the knee. It flexes the leg on the thigh.f The Semimembranosus, Is at the inner side of the thigh ; its upper part is concealed by the semitendinosus and the origin of the long head of the * Varieties. Sometimes the short head does not exist, thereby affording an analogy with animals. Sometimes there is a third head, but more deli- cate, which comes either from the tuber of the ischium or from the long head, and descending along the back of the leg, runs into the tendo achil- lis, corresponding thereby with the arrangement of mammiferous animals. f Varieties. Sometimes it is divided iwto three sections by two transverse tendinous lines. 422 musci.es. biceps, and below* it projects between these two muscles. It is in contact with the posterior surface of the triceps adductor. It arises, by a thick round tendon, from the exterior upper part of the tuberosity of the ischium, which tendon soon be- comes flattened, and sends off the muscular fibres obliquely from its exterior edge to a corresponding tendon below. The latter passes behind the internal condyle and the head of the tibia, dispatches a thin aponeurotic membrane under the inner head of the gastrocnemius, to cover the posterior part of the capsule of the knee joint, and to be fastened to the external condyle. It is inserted, by a round tendon, into the inner and back part of the head of the tibia, just below the joint. The un- favourable insertion of this muscle is compensated for, by the course of its fibres, which gives it great increase of strength. A bursa exists between its tendon above and the quadra- tus; another exists between its tendinous termination, the internal bead of the gastrocnemius, and the capsule of the knee. It flexes the leg on the thigh. SECT. III.—MUSCLES OF THE LEG. These muscles are situated anteriorly, posteriorly, and externally. The Tibialis Anticus, Is situated superficially under the fascia of the leg, at the outside of the spine of the tibia, and in front of the interos- seous ligament. It arises, fleshy, from the head of the tibia, from its outer surface, spine, and from the interosseous liga- ment to within three or four inches of the ankle. It also arises by its front surface from the internal face of the fascia of the leg. A rounded long tendon is formed in front below, into which the fleshy fibres run obliquely, and which, passing through a MUSCLES OF THE LEG. 423 distinct noose of the annular ligament in front of the malleolus internus, crosses the astragalus and os naviculare, and is in- serted into the anterior part of the base of the cuneiforme internum, and into the adjacent part of the metatarsal bone of the great toe. A bursa surrounds the tendon where it passes beneath the annular ligament; another also exists at its lower part. This muscle corresponds with the radial extensors of the arm. It bends the foot, and presents the sole obliquely inwards. The Extensor Longus Digitorum Pedis, Is also superficially placed just under the fascia of the leg and in front of the fibula, being in contact above with the tibialis anticus, and below with the extensor proprius pollicis. It arises, tendinous and fleshy, from the outer part of the head of the tibia, from the head of the fibula, and almost the whole length of its anterior spine ; also from the upper part of the interosseous ligament and the internal face of the fascia of the leg. Its fibres go obliquely downwards and forwards to the tendon which begins not far from its upper end and descends along its anterior margin. About the middle of the leg the tendon splits into four, which are confined by the annular ligament of the ankle, and then diverging, each is inserted into the base of its respective small toe, and expanded over its back part as far as the last phalanx. When'these four tendons first reach the roots of the toes they expand over the back of the articulations there, and send downwards triangular processes which are attached to the base of the first phalanx, and to the tendinous termina- tions of the interosseous muscles. On the back of the first joint the tendon adheres closely to its synovial membrane, and is somewhat cartilaginous. At the second joint the ten- don splits partially into two, which pass somewhat laterally, and then reunite. The tendon then adheres again closely to 424 MUSCLES. the synovial membrane of the third articulation, and finally terminates in the base of the third phalanx. This muscle extends the toes but flexes the foot. A long bursa is found enveloping the tendons where they pass beneath the annular ligament of the ankle. It extends all the joints of the small toes and flexes the foot. The Peroneus Tertius, Is rather an appendage of the extensor longus, is found at its lower outer part, and cannot be naturally separated from it. It arises from the anterior angle of the fibula, and ex- tends between its middle and lower end. It is inserted, by a flattened tendon, into the base of the metatarsal bone of the little toe, and assists in bending the foot. The Extensor Proprius Pollicis Pedis, Is between the lower parts of the tibialis anticus, and the extensor longus. It arises from the fibula between its ante- rior and internal angles, by a tendinous and fleshy origin, which commences about four inches below the head of the fibula, and continues almost to its inferior extremity. A few fibres also come from the interosseous ligament, and from the lower part of the tibia. The muscle being half penniform, the fibres run obliquely to a tendon at its fore part, which passes under a particular gutter of the annular ligament; over the astragalus and sca- phoides and upper internal parts of the foot, to be inserted into the base of the first and second phalanges of the great toe. A bursa invests this tendon when it passes beneath the annular ligament. It extends, as its name implies, the great toe.* • Varieties. A partial effort is sometimes manifested to divide it into two muscles. MUSCLES OF THE LEG. 425 On the outside of the leg, between the fibula and fascia, are the two Peronei muscles. The Peroneus Longus, Arises, tendinous and fleshy, from the fore and outside of the head of the fibula, from the space on its outer side above, between the external and anterior angles, also, from its ex- ternal angle to within a short distance of the ankle. A flattened thick tendon, to which the fibres pass oblique- ly, constitutes the outer face of the muscle. This tendon is lodged in the groove at the posterior part of the malleolus externus, being confined to it by a thick ligamentous noose, and furnished there with a bursa ; it then traverses the outer side of the os calcis, where its passage is marked by a super- ficial sulcus; it then runs through the groove of the os cu- boides, where there is another bursa. Lying deep in the sole of the foot covered by the calcaneo cuboid ligament, and next to the tarsal bones, it is inserted into the base of the in- ternal cuneiform bone, and into the adjacent part of the me- tatarsal bone of the great toe. It extends the foot and inclines the sole obliquely outwards. It corresponds with the flexor carpi ulnaris of the fore-arm. As the tendon experiences much friction at the ankle, on the os calcis, and wThere it winds around the os cuboides, it is not unusual to find in it small sesamoid bones there, espe- cially at the latter place. The Peroneus Brevis, Is concealed in a great degree by the peroneus longus, be- ing situated between the latter and the extensor longus digi- torum. It arises, tendinous and fleshy, from the outer sur- face of the fibula, commencing about one-third of the length of the bone from its head, and continuing almost to the ankle. A tendinous facing exists externally also in this muscle, to which its fibres proceed obliquely. This tendon is continued through the fossa at the back part of the malleolus externus, VOL. i.—3 H 42(j MUSCLES. being covered by the tendon of the peroneus longus, and con- fined by the same ligamentous noose ; passing through the superficial fossa at the outer side of the os calcis, it is in- serted into the external part of 'the base of the metatarsal bone of the little toe. It extends the foot and presents the sole obliquely down- wards. It also corresponds with the flexor manus cubitalis.* Triceps Surae. The muscular mass on the back of the leg constituting its calf, is formed by the two following muscles, which with much reason may be considered as composing only one. Ana- tomists who view them in this latter light describe them under the name of Triceps Surae, of which the Gastrocne- mius portion has two heads, and the Soleus but one. 1. The Gastrocnemius is the most superficial muscle on the back of the leg, and conceals the others in consequence of its breadth. It comes from the condyles of the femur by two heads. One head arises, tendinous, from the upper back part of the internal condyle, and fleshy from the ridge lead- ing to the linea aspera; the other head arises, by a broad tendon in the same wTay, from the external condyle and the ridge above it. A triangular vacancy is left between the heads of the muscle for the passage of the popliteal vessels ; the heads then join together, but in such a way that the ap- pearance of two bellies is distinctly preserved, of which the internal is the largest. The muscular fibres pass from a * broad tendinous facing on the back to a corresponding one on the front surface of the muscle, from the latter of which comes the tendo achillis. 2. The Soleus is beneath the Gastrocnemius, and arises, fleshy, from the posterior part of the head of the fibula, and from the external angle of that bone, for two-thirds ortte • Varieties. It is sometimes double. MUSCLES OF THE LEG. 427 length down, behind the peroneus longus. It also arises, fleshy, from the oblique ridge on the posterior surface of the tibia, just at the lower edge of the popliteus muscle, and from the internal angle of the tihia for four or five inches. The two heads are separated for the passage of the posterior tibial vessels. The body of this muscle has a great intermixture of ten- dinous matter in it, and from its lower extremity proceeds another origin of the tendo achillis. About three or four inchesjabove the heel, this tendon joins the anterior face of the tendon of the gastrocnemius, and by the union of the two the tendo achillis is completed, and then inserted into the posterior inferior surface of the os calcis at its tubercles. The tendon becomes more round as it descends. These extend the foot, and are all-important in walking. A bursa is between their tendon and the os calcis. The Plantaris, Is a singular little muscle, concealed by the gastrocnemius, and has a short fleshy belly and a long tendon. It arises,, fleshy, from the ridge of the os femoris, just above the exter- nal condyle, passes across the capsular ligament of the joint, and adheres to it in its course; the belly terminates some- what below the head of the tibia, in a long, delicate tendon, which descends between the inner head of the soleus and the gastrocnemius. At the place where the tendons of these unite, the tendon of the plantaris emerges from between them, and, running at the inner edge of the tendo achillis, is inserted into the in- side of the os calcis, just before the insertion of the latter. It extends the foot. This muscle is sometimes wanting. It contributes so little to the motions of the foot, and in other respects is of such doubtful use, that its proper destination is uncertain. In some mammiferous animals it is large and im- portant ; perhaps, therefore, in the human subject, it is one of the links connecting us with animals, of which there are many evidences in the muscular system. m MUSCLES. The Popliteus, Is a triangular muscle on the back of the knee joint. It arises, by a thick round tendon, from a deep depression on the exterior face of the external condyle; passes through the capsular ligament, being connected with the external semi- lunar cartilage; and then forms a fleshy belly which passes obliquely inwards and downwards. It is inserted, fleshy, into the oblique ridge on the back of the tibia, just below its head, and into the triangular depres- sion above it. A bursa exists between its origin and the cap- sular ligament; its tendon is in contact with the synovial membrane of the joint. It bends the leg, and when bent, rotates it inwards. The Flexor Longus Digitorum Pedis Perforans, Is behind the tibia, and at the inner edge of the tibialis posticus. It arises, by an acute, tendinous, and fleshy begin- ning, from the back of the tibia a little below the popliteus muscle, its origin being continued along the internal angle of the tibia almost to the ankle joint. It arises also, by tendi- nous and fleshy fibres, from the outer edge of the tibia, just above its connexion with the fibula at the ankle, and between this double order of fibres the tibialis posticus lies. The fibres pass obliquely into a tendon at the posterior edge of the muscle which runs in the groove of the internal malleolus, and is confined there by a strong ligamentous sheath. The tendon then gets to the sole of the foot along the sinuosity of the os calcis, and, being joined by a conside- rable tendon, detached from the flexor longus pollicis, it divides into four branches which are appropriated to the four small toes. These tendons are inserted into the bases of the last pha- langes of the lesser toes, are very near the tarsal bones, and, from perforating the tendons of the flexor brevis, correspond with the flexor perforans of the hand. A bursa exists where the tendon passes along the tibia and the os calcis; and MUSCLES OF THE LEG. 429 another is found in the sole of the foot, enveloping this ten- don and that of the flexor longus pollicis. A fifth tendon is sometimes observed, which splits and goes to the second bone of the small toe; this occurs when the latter is not supplied from the flexor brevis. This muscle flexes the small toes and extends the foot. The Flexor Longus Pollicis Pedis, Is a stout muscle formed of oblique fibres, and situated on the back part of the fibula, at the outer side of the tibialis posticus. It arises by an acute, tendinous, and fleshy begin- ning from the posterior flat surface of the fibula, commencing about three inches from its head, and continuing almost to the ankle. The tendon of this muscle is large and round, it forms gradually, and constitutes a facing to the posterior edge of the muscle. It passes through a superficial fossa of the tibia, at the back of the ankle near its middle, and from thence through a notch in the back edge of the astragalus to the sole of the foot; at the latter place it crosses the tendon of the flexor longus digitorum, and gives off to it the branch just mentioned, which goes, principally, to the second toe. This tendon is deeper seated in the foot than the other. The tendon of the flexor longus pollicis is inserted into the last joint of the great toe. It bends the great toe, and from its connexion with the others will bend them also. A bursa invests its tendon in the canal of the astragulus, and along the os calcis; another, as stated, is common to it and the last muscle; and a third invests the tendon along the metatarsal bone, and the first phalanx of the great toe.* • The variations in this muscle consist, principally, in the manner of dis- tributing its tendon to that of the small toes, 430 MUSCLES'. The Tibialis Posticus, Is placed between, and concealed by the last two muscles. It arises, by a narrow fleshy beginning, from the front of the tibia, at the under surface of the process which joins it to the fibula, and then gets to the back of the leg through a hole in the Interosseous ligament. It continues its origin from the whole of the interosseous ligament, and from the surfaces of the tibia and fibula bordering on this ligament, excepting one-third of the lower part of the fibula, and rather more of the lower part of the tibia. The fleshy fibres run obliquely to a middle tendon which passes in the groove at the back of the malleolus internus, and is confined there by a fibro-cartilaginous noose, and in- vested by a bursa. It is inserted into the posterior internal part of the os naviculare; and also divides in such a way as to be inserted into the internal and external cuneiform bones, into the os cuboides, and os calcis. It extends the foot, and presents the sole obliquely inwards. It corresponds with the flexor radiales of the hand. SECT. IV.—OF THE MUSCLES OF THE FOOT. The Extensor Brevis Digitorum Pedis, Is the only muscle of the superior surface of the foot It is placed beneath the tendons of the extensor longus, and arises, tendinous and fleshy, from the fore upper part of the os calcis. It forms a short, fleshy belly, which is partially divided into four parts; from these parts proceed as many tendons, which, crossing very obliquely the tendons of the extensor longus; are inserted into the great toe, and the three next toes, by joining with the tendons of the extensor longus, which are spread over their backs. It extends the toes.* • Varieties. The internal part or belly, is sometimes distinct from the ad- joining. In some very rare cases all the bellies are insulated, as in birds. Sometimes it sends a tendon to the little toe. MUSCLES OF THE FOOT. 431 When the Aponeurosis Plantaris is removed, we see three muscles; the middle one having been covered by the large central portion of the aponeurosis, is the Flexor Brevis Di- gitorum Pedis, the outer is the Abductor Minimi Digiti, and the inner the Abductor Pollicis Pedis. The Flexor Brevis Digitorum Pedis, Arises, fleshy, from the large tubercle of the os calcis, by a narrow beginning; also from the interior surface of the apo- neurosis, and the tendinous septa between it and the conti- guous muscles. It forms a fleshy belly, going nearly as far forwards as the middle of the metatarsal bones; there it divides into four ten- dons, which go to the smaller toes. These are perforated by the tendons of the flexor longus, and are inserted into the sides of the second phalanges. The tendon for the little toe is often deficient It bends the second joint of the toes. By detaching this muscle from its origin and turning it down, we bring into view the tendon of the Flexor Longus Digitorum Pedis; and the attachments behind, of the latter, to the tendinous slip from the Flexor Longus Pollicis,—to the Massa Carnea Jacobi Sylvii, or Flexor Accessorius,— and before, to the Lumbrirales muscles. The Flexor Accessorius, Is at the outside of the tendon of the flexor longus. It arises, fleshy, from the inside of the sinuosity of the os cal- cis, and, by a thin tendon, from the outside of the bone before its tubercle. It is inserted, fleshy, into the outside of the tendon of the flexor longus, just at its division into four tendons. Like a second hand at a rope, it assists in flexing the toes. 432 MUSCLES. The Lumbricales Pedis, Are four small tapering muscles which arise from the ten- don of the flexor longus just after its division, or while it is in the act of dividing. One of them is appropriated to each lesser toe, and is inserted into the inside of its first phalanx, and into the tendinous expansion that is sent off from the ex- tensor muscle to cover its dorsum. They increase the flexion of the toes and draw them in- wards. The Abductor Pollicis Pedis, Arises, tendinous and fleshy, from the internal anterior part of the large tuberosity of the os calcis, from a ligament ex- tended from the tuberosity to the sheath of the tendon of the tibialis posticus, from the internal side of the naviculare, and from the cuneiforme internum. It forms the internal margin of the sole of the foot, and is, inserted, tendinous, into the internal sesamoid bone and into the base of the first phalanx of the great toe. It draws the great toe from the rest. The Flexor Brevis Pollicis Pedis, Is situated immediately at the exterior edge of the abduc- tor pollicis. It consists of two bellies, which are parallel with each other, and separated by the tendon of the flexor longus pollicis; one is inseparably connected with the ten- don of the abductor pollicis, and the other with the adductor pollicis. It arises, tendinous, from the under part of the os calcis, just behind its connexion with the os cuboides, and from the under part of the external cuneiform bone. The internal belly is inserted, tendinous, into the internal sesamoid bone along with the tendon of the abductor pollicis, and the external belly is inserted, tendinous, into the exter- nal sesamoid bone along with the tendon of the adductor pol- MUSCLES OF THE FOOT. 433 licis. Each insertion is continued on to the base of the first phalanx of the great toe. It flexes the great toe. The Adductor Pollicis Pedis, Is situated at the outside of the flexor brevis, and is ex- tended obliquely across the metatarsal bones. It arises, ten- dinous, at the external part of the foot, from a strong liga- ment which is stretched from the os calcis to the os cuboides, and from the roots of the second, third, and fourth metatarsal bones. It is inserted, tendinous, into the external sesamoid bone, which insertion is continued to the first phalanx of the great toe, and is closely united to the tendon of the external head of the flexor brevis pollicis. It draws the great toe towards the others. The Abductor Minimi Digiti Pedis, Forms the external margin of the sole of the foot, and is immediately beneath the aponeurosis plantaris. It arises, tendinous and fleshy, from the outer side of the tuber of the - os calcis, and also from the exterior part of the base of the metatarsal bone of the little toe. It is inserted, by a rounded tendon, into the exterior part of the base of the first phalanx of the little toe. It draws the little toe from the other toes. The Flexor Brevis Minimi Digiti Pedis, Is just within the tendon of the abductor minimi digiti. It arises from the ligament which is extended from the tubero- sity of the cuboid bone to the heads of all the metatarsal bones; also, from the root of the fifth metatarsal bone. It is inserted, by a tendon, into the lower part of the first phalanx of the little toe, at its base, and into the head of the metatarsal bone of the same toe. It bends the little toe. vol. i.—3 I 434 MUSCLES- The Transversalis Pediv, Is placed beneath the tendons of the flexor muscles.* It is small, and lies across the anterior extremities of the meta- tarsal bones. It arises, tendinous, from the capsular liga- ment of the first joint of the little toe ; it also arises from the capsule of the first joint of the next toe. It is inserted into the exterior face of the common tendon of the abductor and flexor brevis pollicis, at the external sesamoid bone. It approximates the heads of the metatarsal bones. The Interosseous Muscles are seven in number, four of which may be seen on the upper surface of the foot. There are two to the first small toe, two to the second, two to the third, and one to the fourth or little toe. The muscles seen on the upper side of the foot are for the most part double headed, that is, they arise from the contiguous surfaces of the metatarsal bones. The Interosseus Primus Digiti Primi Pedis, or the Abductor Indicis Pedis, Is seen superiorly. It is placed between the metatarsal bone of the great toe and the first small toe, and arises, fleshy, by a double head, from the opposed surfaces of their roots. It is inserted, tendinous, into the inside of the root of the first joint of the first small toe, and pulls it inwards. The Interosseus Secundus Primi Digiti, or the Adductor In- dicis Pedis, Is also external or above. It is situated between the me- tatarsal bones of the first and second small toes, arising from the opposed surfaces of their roots by a double fleshy and ten- dinous head. ' The sole is presumed to be upwards MUSCLES OF THE FOOT. 435 It is inserted into the outside of the first phalanx of the same toe, by a tendon. It draws this toe outwards. The Interosseus Primus Secundi Digiti Pedis, or the Abduc- tor Medii Digiti, Is at the bottom of the foot, and arises from the inside of the metatarsal bone of the second small toe. It is inserted into the inside of the first phalanx of the se- cond toe. It draws this toe inwards. The Interosseus Secundus Digiti Secundi^ or the Adductor Medii Digiti, Is seen at the upper part of the foot, between the second and third metatarsal bones of the lesser toes, arising from the opposite surfaces of their roots. It is inserted, tendinous, into the outside of the base of the first phalanx of the second small toe. It draws this toe outwards. The Interosseus Primus Digiti Tertii, or the Abductor Tertii Digiti, Is in the sole of the foot. It arises from the inside of the metatarsal bone of the third toe, near its root, and is insert- ed, tendinous, into the inside of the base of the first phalanx of the third toe. It draws this toe inwards. The Interosseus Secundus Digiti Tertii, or the Adductor Tertii Digiti, Is seen on the upper surface of the foot, occupying the in- terval of the metatarsal bones of the third and fourth small toes, and arises, by a double head, from the opposite surfaces of their roots. 436 MUSCLES. It is inserted, tendinous, into the outside of the root of the first phalanx of the third small toe. It draws this toe outwards. The Interosseus Digiti Minimi, Is on the under surface of the foot. It arises from the in- side of the base of the metatarsal bone of the fourth small or the little toe, and is inserted, tendinous, into the inside of the first phalanx of the little toe. It draws this toe inwards. It is also called Abductor Minimi Digiti Pedis; but this name has rather a tendency to confuse, as one of the muscles, as stated, on the outer side of the sole of the foot, has the same name. BOOK IV. OF THE ORGANS OF DIGESTION. The organs of digestion consist in an uninterrupted canal, extending from the lips to the anus; and of numerous glan- dular bodies placed all along its track, for pouring their secretions into it This canal, called alimentary, (Ductus Cibarius,) is in three principal portions : the superior, the middle, and the inferior or terminating. The superior portion is composed of the mouth, the pharynx, and the oesophagus. The middle, of the stomach and small intestine. And the inferior, of the large intestine. The glandular organs are the salivary glands, the pan- creas, the liver, the spleen, and an extremely numerous set of muciparous glands, extending from one end to the other of the canal. The organs of digestion may be divided, according to their physical functions, into those of mastication and deglutition, and into those of assimilation. BOOK rv. PART I. Organs of Mastication and Deglutition. CHAPTER I. OF THE MOUTH. The Mouth, {Cavum Oris,) occupies the space, in the in- ferior part of the face, between the upper and the lower jaw. It is separated from the nose by the palatine processes of the superior maxillary and palate bones, and by the soft palate, which is continued backwards from them. It extends from the lips in front, to the soft palate and pharynx behind, and its floor is formed by the mylo-hyoid muscles. The anterior and lateral periphery of the mouth is consti- tuted by the muscles of the lips and cheeks ; principally the orbicularis oris and the buccinators, covered externally by common skin, and internally by the lining membrane of the mouth. The cavity of the latter is divided into two portions, by the projection of the teeth and of the alveolar processes of the upper and under jaws; these two portions, when the teeth are complete, are separated from each other while the mouth is closed. The anterior portion, which is sometimes called the vestibule of the mouth, varies its size very consi- derably in mastication, and has its parietes extremely move- able. The capaciousness of the posterior admits also of much change, by the motions of the tongue and by the depression of the lower jaw. OF THE MOUTH; 439 The whole cavity of the mouth is lined by a membrane, continued over the lips from the skin, and, in many respects, strongly resembling the texture of the latter; it is, how- ever, much finer; is furnished every where with an epidermis; is very vascular, and has beneath it a great number of muci- parous glands. Its texture undergoes some changes, accord- ing to its position, upon the lips and cheeks, upon the gums and palate, and upon the tongue; all of which will be allud- ed to in due season. This lining membrane of the mouth, for the most part thin and very flexible, forms, at several points, folds or duplica- tors. Four of them are situated on the middle line of the body, and are called frenula; one goes from the posterior face of the upper lip to the middle palate suture in front of the central alveolar processes of the upper jaw; a second goes from the posterior face of the lower lip to the front of the symphysis of the lower jaw; a third goes from the under part of the tongue to the posterior face of the symphysis of the lower jaw, (frsenulum linguae); and the fourth goes from the front of the epiglottis cartilage to the middle of the root of the tongue. Besides these, there are some other duplications, which will be mentioned in their proper order. The Lips (Labia) are always somewhat thicker at their loose margins than elsewhere; the skin which covers them there is remarkable for its vascularity, and changes its tex- ture insensibly as it is continued from the face to the lining membrane of the mouth. The upper lip is longer and thicker than the lower, is some- what pointed in the centre, and has on its front surface a ver- tical depression, (philtrum,) beginning at the septum of the nose and going downwards to the centre of the lip. This depression is the remains of a fissure which always exists between the two halves of the lip, in the early foetal or forming stage. The junction of the extremities of the lips consti- tutes the corners of the mouth (anguli oris.) The lips are composed of muscular fibres, much blended with adipose matter. The muscles which concur to form 440 ORGANS OF DIGESTION them are the orbicularis oris and the buccinators; besides which, the upper lip is furnished on each side with the two levators, with the depressor, and the zygomatici; while the lower lip has its two depressors and a levator. See muscles of the face. CHAPTER II. OF THE TEETH. The Teeth (Denies') are by far the hardest portions of the human fabric; and though they bear in their composition and appearance a strong analogy with bone, yet they differ from it in regard to their duration, to their mode of development, to their partial nudity, to their nutrition, and the manner in which they are united to the body. The greater part of the length of each tooth is implanted into the alveolar process of the jaw, and the part so fixed is technically called the root; immediately beyond this a small portion of the tooth is embraced by the gum, this is the neck; and the free or projecting part of the tooth is its body. SECTION I. The whole number of teeth in the adult is thirty-two, six- teen in each jaw, and when healthy they are all fixed with so much firmness by the gomphosis articulation, that the very slight degree of motion, which by force they may be caused to exhibit, is scarcely perceptible. The differences existing in their shapes, have caused anatomists to classify them accordingly; on each side of the middle line of each jaw there are two Incisors, one Cuspated, two Bicuspated, and three Molar teeth. There are also some peculiarities, as they belong to the upper or to the lower jaw; but they OF THE TEETH. 441 correspond exactly with their fellows on the opposite side of the same jaw. The Incisors (Denies Incisivi) are next to the middle line, and are named from their being brought to a straight cutting edge, like a chisel, by being bevelled from behind. They are somewhat convex on their anterior faces, but behind they are very concave ; owing to their thinness for some distance from the cutting edge, they are apt to be broken. In early life their cutting edge is slightly serrated. They have each but one root, which is conoidal, terminates by a sharp point, and is not unfrequently impressed longitudinally on each side by a superficial furrow. The central incisors of the upper jaw are broader and longer than the outer ones ; the anterior face of the latter is more convex, and their cutting edge more rounded. The in- cisors of the lower jaw are much narrower than those of the upper, and have their roots flattened on the sides; they do not differ essentially among themselves, except that the ex- ternal ones are somewhat wider than the internal. The enamel of the incisors is continued farther down, and is thicker on their anterior and posterior surfaces than late- rally ; it is also thicker on the front than on the back part* The Cuspated Teeth (Dentes Cuspidati, Canini) are next to the incisors, one on each side. Their body is conoidal, and is brought to a sharp point at its summit; the principal obliquity, in effecting the latter, being on the side of the in- terior of the mouth. They are more convex externally than the incisors, but not so concave internally, they are also thicker and more cylindrical. They have but one root, which is conoidal, and which, as also the body, is longer than the corresponding portions of any of the other teeth. They stand nearly perpendicular, and are more covered on their sides with enamel than the incisors. The cuspated teeth of the upper jaw have longer roots * Natural History of the Human Teeth, by J. Hunter, London, 1778 VOL. I.—3 K 442 ORGANS OF DIGESTION. than those of the lower, and are called, in common language, eye-teeth, those of the lower jaw are sometimes called sto mach teeth. The Bicuspated Teeth (Dentes Bicuspidati,) two in number on each side, are situated behind the cuspate, they are also called small molar. They are almost precisely alike, with the exception that the first is smaller and resembles rather more the type of the cuspidatus than the second does. Their body is very nearly cylindrical, being flattened, however, on the faces next to adjoining teeth. The masticating surface of the body is formed into two points, whence the name, one external, and the other internal; the former is the longest and thickest, and consequently the most conspicuous. The enamel forms an almost circular crown, covering the project- ing parts of these teeth. The root of each one is single, but has a deep and well marked fossa on each side running its whole length, and presenting the semblance of an effort at duplicity, it is also conoidal, and sometimes in the upper jaw bifurcated at its end. The bicuspate teeth of the upper and of the lower jaw re- semble each other so strongly that the difference between them is not striking; it is. however, determined by those of the upper jaw being rather more voluminous and ovoidal in their bodies, and having rather longer and larger roots. The Molar Teeth (Denies Molares,) three in number on each side, succeed the bicuspated. They are well charac- terized by their greater size. Their bodies are almost cuboidal, with rounded angles, and are protected with a cir- cular crown of enamel; their grinding surface has five points, three externally, and two internally: the rule, however, is not uniform, as they frequently have only four, and some- times in the upper jaw only three. The first molar is the largest of any, and very generally has five points ; in the upper jaw it has three roots, two of which are outward, and the other inwards; but in the lower jaw it has only two roots, one before the other. OF THE TEETH. 443 The second molar of each jaw, with the exception of it9 being smaller than the first, presents no essential difference from it, either in regard to its body or roots. The fifth point is sometimes not so well developed. The third molar resembles the other two in its body but is smaller than either of them. Most frequently its roots instead of diverging from each other and standing out dis- tinctly, are imperfectly developed, and fused together. Some slight separation at their extremities, and the longitudinal depressions on their sides, mark the effort to form three roots for the tooth of the upper jaw, and two for the lower, accord- ing to the general rule. Owing to this tooth growing at the posterior extremity of the alveolar process; in a place where, from the preceding development of the other teeth, it is much cramped for room : it is not only imperfectly evolved in most cases, but it often takes a very irregular direction, its grind- ing surface sometimes looking forwards and sometimes back- wards. The Alveolar Processes in each jaw form a semi-elliptical row of sockets, for the insertion of the roots of the teeth into them. These processes and the teeth, as Mr. Hunter has very properly explained, have such a mutual dependence upon each other, that the destruction of the one is inevitably followed by that of the other; " if we had no teeth, it is likely we should not only have no sockets, but not even these pro- cesses in which the sockets are formed."* The semi-ellip- tical arrangement observed by the teeth is such, that when the mouth is closed, the exterior circumference of those above projects beyond those below; this is more obviously the case in front; but it also prevails at the sides, and depends prima- rily upon the greater breadth of the incisors of the upper jaw. The grinding surface of the under row, as a whole, is slightly concave from before backwards, while the opposed surface of the upper row has a corresponding convexity. Each row, viewed collectively, forms a single edge in front, but, after •Loc. cit. p.7. 444 ORGANS OF DIGESTION. having passed the cuspidati, it becomes thicker, forms a dou- ble edge, and is continued backwards in that state. SECT. II.—OF THE TEXTURE AND ORGANIZATION OF THE TEETH. The teeth consist in two kinds of substance, one of which is ivory or bone like, and the other enamel. The Enamel forms the periphery of the body of a tooth, and is distinguished by its whiteness, its brittleness, its semi- transparency, and a hardness so considerable that it soon takes down the edge of the best tempered saw or file, so that it is very difficult to penetrate it. It forms a crust upon the body scarcely half a line in thickness, is more abundant upon the grinding surface, and is reduced to a thin edge where it terminates at the neck. When broken, it is seen to be fibrous, and the fibres are so placed as to pass in a direc- tion from the surface towards the centre of the tooth: by which all the friction to which the fibres are exposed is applied against their extremities; an arrangement precisely suited to resist their being rubbed down in mastication and also to prevent their splitting. Enamel consists principally in a phosphate of lime, with a very small proportion of gelatine. When immersed in a weak acid, its form is retained, but the slightest disturbance after- wards causes it to crumble down into a white pulp. When animals are fed upon madder, the colour of the enamel is not affected;* though it may be changed by dyes applied exter- nally, as exhibited by the inhabitants of the Pelew Islands, who, by the use of plants turn it black, and by persons who chew tobacco, in whom it becomes yellow. It is entirely de- void of blood-vessels. When exposed to heat it becomes very brittle, cracks off from the enclosed bony part of the * J. Hunter, loc. cit. I have also verified the same opinion by the same experiment. TEXTURE AND ORGANIZATION OF THE TEETH. 445 body, and presents a singed appearance from the small quan- tity of gelatine in it. The enamel is not so thick on the deciduous as on the per- manent teeth ; it is thicker on the cuspidati than on the inci- sores, and on the first molar than on the second and third. It is very readily dissolved in strong nitric or muriatic acid. The Osseous portion of the tooth is by much tire most abun- dant, as it forms the root, the neck, and the body also with the exception of the crust of enamel upon it. In its texture it strongly resembles the petrous bone and is even harder than it, but has no cellular arrangement within. It consists in a series of longitudinal laminae, one within the other, and when decomposed presents about seventy parts of the phosphate of lime and other calcareous combinations, with about twenty of gelatine and ten of water.* The bony part of a tooth has very nearly the same form with the entire body,hence, upon the grinding surface, we have the same modifications of shape as when the enamel is left on. The application of a heated iron to it, turns it to a deep black from the abundance of animal matter in it, which is one way to mark out decidedly the distinction between it and enamel. The animal substance, when separated from the calcareous, by muriatic acid, is more compact than the corresponding substance of bone, but, like it, is soft and flexible.! The bony part is not vascular; Mr. Hunter, after repeated trials in old and young subjects upon this point, never suc- ceeded in making an injection of it; neither could he trace vessels from the pulp to a growing tooth. In growing ani- mals fed upon madder, he found that the portion which was formed previously to the commencement of this diet retained its primitive colour, while the part formed during the admi- nistration of the diet was affected by it and turned red; again, if the animal were permitted to live some weeks after the * Pepys. f J. Hunter, loc. cit. 446 ORGANS OF DIGESTION. madder was suspended, to the preceding condition was super- added a new layer of white. In this experiment, a conclu- sive difference from common bone is established; for besides, in all cases, the facility of injecting the latter with size, it is capable of being dyed throughout by the administration of madder; though the formed parts do not take the latter so readily as the forming. These experiments, which are con- firmed by my own observations, prove satisfactorily the to- tal absence of blood vessels in the texture of the teeth; and that the colouring matter, when fixed in them, does not de- pend upon a circulation, but upon its being deposited as the tooth grows, and left there permanently. The teeth are consequently not subject to a commutation of particles and to being continually re-modelled as the bones are, but when once formed they remain in the same state, without change. Every tooth has within its body a cavity, which varies in form and size according to the class to which the tooth belongs ; this cavity is continued as aconoidal canal through the whole length of each root, and terminates, by a small open- ing, at its point The cavity is smooth on its internal sur- face, and is filled with a soft pulpy matter which has no adhesion to the sides of the tooth, but receives through the opening in the root, an artery, a vein, and a nerve. The surface of the pulp is moistened by a slight exhalation, and its principal bulk seems to be formed by the nerve, on which the vessels ramify; the latter in youth are much more abun- dant than in old age.* The base of each projection on the grinding surface of a tooth is hollowed out for receiving a process from the pulp. The latter is supposed, by M. Ser- res, to be a ganglion, it must however be a point of much difficulty to fix this character upon it, as the fine cellular substance which holds its constituents together may be readily mistaken for soft nervous fibres. The arteries of the teeth of the upper jaw are derived from the alveolar and the infra-orbitar, and the nerves from the • Serres, Essai sur l'Anat. et Pbysiol. des Dents, Paris, 1817. TEXTURE AND ORGANIZATION OF THE TEETH. 447 second branch of the fifth pair. The arteries of the teeth of the lower come from a single branch of the internal maxil- lary, and the nerves from the third branch of the fifth pair. The inferior maxillary, or dental artery, and nerve, go through the canal in the centre of the spongy structure of the lower jaw, and send off branches successively to the roots of the teeth. The residue of the artery and nerve issue through the anterior mental foramen. The teeth have been, till lately, very generally ranged among the bones belonging to the skeleton; the continental anatomists* are, however, now more disposed to view them as the production of the dermoid tissue, like the nails and the hair; and to withdraw them from the class of bones for the following reasons. The rudiments of the bones are always in a cartilaginous state, and they are gradually changed from that condition to the perfect bone; the teeth are never so, for the secretion which forms them is from the beginning deposited in the state in which it ever afterwards remains. The bones* are all furnished with a periosteum; the teeth are not, but have the surfaces of their bodies ex- posed to the air. The general softening of the skeleton which occurs in some cases of rickets, never is manifested in the teeth. The texture of the bones is penetrated in every di- rection with blood-vessels, but only the central pulp of the teeth is furnished with the latter. The teeth are composed of two kinds of calcareous matter, one ivory-like the other enamel; the bones on the contrary have but onc.f It is .also said by naturalists that, in mammiferous animals, the teeth present insensible transitions from their most perfect state, to a lamellated condition resembling horns and nails.\ Some animals, as the shark, have the teeth only adhering to the gum and not fixed in sockets, others have them in the sto- mach, both of which circumstances serve to illustrate still * J. F. Meckel, Hipp. Cloquet, Breschet, Serres, &c. f Serres, loc. cit. t Traducteurs de J. F. Meckel. ■148 ORGANS OF DIGESTION. further the independence of the teeth, upon the osseous sys- tem, and that their being fixed in sockets belonging to the latter is merely a collateral and not an essential arrangement SECTION III. The Gums (Gingivae) are a continuation of the lining mem- brane of the mouth over the alveolar processes, but its tex- ture there is much changed; as it becomes more fibrous and vascular, and loses much of its sensibility and capability of being extended. As the gums cover both the lingual and the buccal circumference of the alveolar processes, they adhere very closely to the periosteum, and send in partitions through the interstices between the teeth. They also adhere tightly to the neck of each tooth, so that when the latter is drawn, the gum, unless previously detached, is apt to be lacerated; this adhesion is by a sort of rounded or partially doubled edge, that admits of a slight degree of motion, and which from its thickness, if it be removed by ulceratiou or by pres- sure, causes the tooth to appear to project unnaturally from its socket. The teeth, from being united to the jaw7 by the gum, and by the periosteum being continued over the cavity of the socket; have preserved to them that degree of yield- ing motion which prevents them, on their unexpected and forcible application to hard bodies, from being fractured, and also saves their sockets.* SECT. IV.—ON THE FORMATION OF THK TEETH. The teeth before they become visible are formed in the interior of the maxillary bones. Their rudiments consist in a vascular pulpy substance, having somewhat the shape of the future tooth, and surrounded by two membranes or sacs. The external sac is soft, fibrous, and spongy, and accord * J. Hunter, loc. cit. FORMATION OF FHE TEETH. 449 ing to Mr. Hunter, is destitute of vessels. It lines the inte- rior of the socket thereby forming its periosteum ;* adheres closely by its inferior end to the dental nerves and blood vessels, and by its superior one to the cartilaginous thicken- ing wiiich exists on the margins of the gums of infants. Fox, Blake, and Meckel, consider this sac vascular, which I think more probable from its being a continuation of the pe- riosteum or acting as such. Mr. Hunter might therefore mean that it was comparatively destitute of vessels and not totally. It is more spongy, loose, and soft, than the external sac, and owing to its adhesion to the gum may, by pulling at the latter, be readily drawn out entire with all its contents. The in- ternal sac is extremely vascular, and when successfully in- jected appears red all over; it is very thin and transparent, and was considered by Bichat as a serous membrane, which is inconsistent with its vascularity. It adheres to the ex- ternal sac where the latter corresponds with the gum, but is elsewhere detached from it with the exception of its base, where it is united by the medium of the vessels that penetrate to the pulp, and in doing so it obtains its extreme vascu- larity from these vessels. Between it and the pulp there is a mucilaginous fluid like the synovia of the joints ;f which causes the internal sac to protrude like a hernia, if a small puncture be made through the parietes of the external one. The internal sac forms an envelope to the vessels and nerves of the pulp, and being reflected along them, terminates by adhering to the base of the pulp. When the tooth protrudes through the gum this capsule is perforated at its apex, and wastes away, like the gum, till the body of the tooth is suffi- ciently advanced. The two capsules which are then to be con- sidered as the periosteum of the socket and of the root of the tooth, adhere closely to the neck of the latter and to its root. These sacs, or follicles as they are sometimes called, are visible in the tenth wTeek of uterine existence. The Pulp, or germ of the tooth (Pulpas Dentis) is a very * Serres, loc. cit. f Hunter, loc. cit. VOL. I.—3 L 450 ORGANS OF DIGESTION'. vascular body, and adheres to the socket only at its bottom, where the vessels enter; it becomes sufficiently distinct about the fourth month of foetal existence, and rises up then from the base of the internal membrane of the sac like a small simple tubercle. In developing itself it acquires the precise form peculiar to each tooth, and is actually the mould for it; it is surrounded by a very fine vascular web, which is detached from it with much difficulty. The ossification of a tooth first commences on that surface of the pulp next to the gum, by one or more points according to the number of projections, which the future tooth is to have on its grinding surface. The osseous deposite in its very early stage is thin, soft, and elastic, but soon acquires a bard consistence. The incisors begin to ossify by three points, the cuspidates by one, the bicuspis by two, and the molaris by four or five. The several points of ossification continue to increase till their bases come into contact, they then coalesce, and afterwards the tooth grows as an entire body. The triturating surface of the tooth being first formed after this fashion, a deposite of bone then takes place along its edges, till the body of the tooth with the cavity in its centre is completely built up. In this progress it gradually surrounds the pulp, till the whole of the latter, excepting its base, is covered with bone. The adhesion of the pulp to the new formed bone is such as to require some slight force to separate them, but this may be done without rupturing either the one or the other, their surfaces which were in contact are perfectly smooth, neither is there any evidence of a vascular communication between them.* The line of the strongest adhesion is along the latest formed edge of the tooth, and that results from the exact apposition of the pulp and it. The crown or body of the tooth being finally finished, its base is somewhat contracted, and thus forms the neck of the tooth. In the subsequent process of the ossification of the • Hunter, Serres, Meckel, loc. cit. FORMATION OF THE TEETH. ],$[ roots, the number of the latter is predetermined and always indicated by the number of distinct vessels and nerves which go to the pulp, there arc therefore three roots to the upper molares, two to the lower, one to the incisors, and so on. When the root is fully formed its extremity is tapered off to a conoidal point, and the canal or hollow in it containing the pulp is diminished to a proportionate size, so that being also conoidal, its external end appears as a very small open- ing, not large enough to admit a bristle. From the preceding account it is clear that the bony part of the tooth is formed by an exudation from the external surface of the pulp ; consequently that the external lamina of the crown is the first one deposited, and is originally of the size which it ever afterwards retains ; and that the pulp con- tinues this secretion of bony matter, from the circumference to the centre, until the tooth, body, neck, and root, is com- pletely formed. The pulp, during this process, diminishes continually in size, but elongates itself at the same time to- wards the bottom of the socket; or, in the words of Mr. Hunter, "is lengthened into a fang." As the fang grows in length, the resistance being at its end, causes the tooth to rise through the gum; the socket, in the mean time, has grasped the neck or beginning fang, and being modelled upon the root, rises w7ith it* Mr. Hunter's experiments on animals interruptedly fed on madder, prove conclusively, that the bony part of a tooth is formed of la- mellae one placed within another; that the outer lamella being the first formed, is consequently the shortest, and that the internal ones lengthen successively. In the formation of a molar tooth, when the body is finished, * The present doctrine about the dermoid origin of the teeth, seems to have presented itself forcibly to the original and sagacious mind of Mr. Hun- ter, for he says, " Both in the body and in the fang of a growing tooth, the extreme edge of the ossification is so thin, transparent, and flexible, that it would appear to be horny rather than bony, very much like the mouth or edge of the shell of a snail when it is growing, and indeed it would seem to grow much in the same manner, and the ossified part of a tooth would seem to have much the same connexion with the pulp as a snail has with its shell.*' Nat. Hist, of Human Teeth, p. 90. 152 ORGANS OF DIGESTION. ossifications shoot from its brim, and proceed to the centre, where, by their union, they form the commencement of two, three, or even more roots. Mr. Hunter says, that also a dis- tinct ossification is frequently found upon the centre of the base of the pulp : and two or more processes, according to the number of roots to be formed, proceed to join it from the circumference of the tooth ; and in this way the fangs of the multiform teeth begin. The secretion of enamel begins shortly after the external 1 ami rue of the bony matter commence being deposited. This secretion, which has its mould always previously formed of the bony part, comes from a pulpy substance adhering to the internal face of the internal capsule. The pulpy substance is placed on the part of the capsule nearest to the gum, and faces the pulp which secretes the bone; whatever emi- nences the one pulp has, the other has the same, but reversed, so that they exactly fit upon each other. This pulp is best seen in the foetus of seven or eight months, and is not very vascular; it is much thinner than the other, and decreases in size as the development of the teeth advances. That which belongs to the incisor teeth is in contact with their concave interior surface, but in the molar it is opposed to their biting surface.* " In the graminivorous animals, such as the horse, cow, &c, whose teeth have the enamel intermixed with the bony part, and whose teeth, when forming, have as many inter- stices as there are continuations of the enamel, we find pro- cesses from the pulp passing down into those interstices as far as the pulp which the tooth is formed from, and there coming into contact with it." " The enamel appears to be secreted from the pulp above described, and perhaps from the capsula which encloses the body of the tooth. That it is from the pulp and capsula seems evident in the horse, ass, ox, sheep, &c.; therefore, we have little reason to doubt of it in the human species. It is a cal- careous earth, probably dissolved in the juices of our body, • Hunter. FORMATION OF THE TEETH. 453 and thrown out from these parts, which act here as a gland. After it is secreted, the earth is attracted by the bony part of the tooth, which is already formed; and upon that surface it crystallizes." " The operation is similar to the formation of the shell of the egg, the stone in the kidneys and bladder, and the gall stone. This accounts for the striated crystallized appear- ance which the enamel has when broken, and also for the direction of these stri»." "The enamel is thicker at the points and bases than at the neck of the teeth, which may be easily accounted for from its manner of formation; for if we suppose it to be always secreting and laid equally over the whole surface, as the tooth grows, the first formed will be the thickest; and the neck of the tooth, which is the last formed part enclosed in this capsula, must have the thinnest coat; and the fang where the periosteum adheres, and leaves no vacant space, will have none of the enamel." '* At its first formation it is not very hard ; for, by expos- ing a very young tooth to the air, the enamel cracks and looks rough ; but, by the time that the teeth cut the gum, the ena- mel seems to be as hard as ever it is afterwards; so that the air seems to have no effect in hardening it." The preceding passages have been extracted literally from Mr. J. Hunter's Natural History of the Human Teeth, not only on account of their graphical value, but to fix upon him the merit of having first considered the human teeth as a se- cretion, an opinion the originality of which is falsely attri- buted to the Baron Cuvier, by Mr. Serres* In infants, for several months after birth, the biting mar- gins of the gums upon each jaw are faced by a cartilaginous rising of some lines in elevation and divided by slight fissures. Its usual appellation is that of Dental Cartilage (Cartilago Dentalis;) it performs the function of teeth, in retaining the nipple, and in mastication, and is analogous to the horny beak of birds, and of some reptiles; it only disappears upon * Anat. et Phys. des Dents, p. 63. 4J4 ORGANS OF DIGESTION. the evolution of the teeth. In the upper jaw it is about three lines wide, and in the lower about two. If it be re- moved by thin slices, successively made, till the margins of the alveoli appear, one arrives by that means at the ends of the dental follicles or sacs; from which it appears that there is no intermediate substance. In the preceding cartilage are found many small glands, grouped about in different parts of it They were discovered within a few years past by M. Serres,* of Paris; are about the size of a millet seed, contain a whitish fluid, and when examined by the aid of a microscope do not appear to have any distinct opening or duct in consequence of which they must be punctured in order to expel their contents. The largest of them are on the internal side of the gum near the molar teeth. According to their discoverer, these glands serve to lubri- cate the dental cartilages of the infant, but after the eruption of the teeth they secrete the substance commonly called Tar- tar, and heretofore falsely attributed to the saliva. Their secretion, being of a fatty nature, keeps up the high and brilliant polish which the teeth have till middle age; it being afterwards altered, the teeth then become more dull and yellow. Salivation produces an excessive secretion and de- posite of tartar from these glands. J. F. Meckel states, that he has never been able to discover them till towards the pe- riod of dentition, from which he is rather induced to consider them as a morbid production depending upon irritation, and probably not differing from little abscesses. SECT. V.—DENTITION. Infants have a set of teeth called Deciduous, from their being lost after a certain period of time. Their whole num- ber is twenty, ten in each jaw, consisting on either side of two incisors; one cuspidatus; and two molares, having a • Loc. cit. DENTITION. 455 shape corresponding with that of the large grinders in the adult. Several of these teeth fall out about the seventh year, and all of them have disappeared about the fourteenth. The time of their first protrusion through the gums is variable, but may, as a general rule, be stated at from the sixth to the eighth month after birth. They appear commonly in pairs. The pairs of the lower jaw have precedence in their protru- sion, and are immediately followed, successively, by their congeners in the upper. The order of protrusion is as follows: The two central incisors from the sixth to the eighth month; The two lateral incisors, from the seventh to the tenth month; The first molar tooth, on each side, from the twelfth to the fourteenth month; The cuspated from the fifteenth to the twentieth month ; The second molar, on each side, from the twentieth to the thirtieth month.* The Deciduous teeth, by a process which will be presently explained, drop from the gums and are succeeded by the permanent teeth. The first permanent molar, about six or seven years of age, by emerging behind the second infant molar, leads the way to the second epoch of dentition, which occurs in the following order : The central incisors fall out about the sixth or seventh year, and are immediately followed by the central permanent incisors; In a few months afterwards, sometimes at the same period, the lateral infant incisors tumble out, and are succeeded by the lateral permanent incisors ; About the ninth year the first molar teeth fall out, and are succeeded by the first bicuspated ; From the ninth to the eleventh year, the second molar* fall out, to be succeeded by the second bicuspated; * Serres, loc. cit. 456 ORGANS OF DIGESTION. From the eleventh to the twelfth, the infant cuspated arc followed by the adult cuspated ; About the end of the twelfth year, the second permanent molars protrude behind the first permanent; And, finally, from the sixteenth to the twenty-fifth year, the third permanent molars, or the Dentes Sapiential, make their appearance. In the jaw of a foetus of three or four months after concep- tion, the beginning of the alveolar processes may be observ- ed, in the condition of a longitudinal groove, deeper and more narrow in front, more shallow and wider behind, and in the bottom of the groove are small transverse ridges, dividing it into superficial depressions. From this simple condition, ridges begin to shoot out from the opposite sides of the canal near its brim, and form, by their junction, arches across it; more matter being added to these arches, they make, in their progress, a sort of cell for each tooth, open on its alveolar surface. This opening is nearer the internal circumference of the alveolar processes, so that the teeth are almost cover- ed, and probably for the reason advanced by Mr. Hunter, that the gums may be firmly supported before the teeth come through. The rudiments of the teeth which are earliest in their ap- pearance may be found in a foetus of two or two and a half months; and at the expiration of three months, it is said that all the germs of both sets of teeth exist in a manner to be dis- tinguished.* The germs of this period are lodged in mem- branous folds belonging to the gum, to which those of the first dentition are immediately attached, while those of the second are suspended by pedicles of a line or two in length, which circumstance alone permits them to be distinguished. At four months all the germs are contiguous to each other, with the exception of the incisors; shortly afterwards they begin to be separated by the rudiments of the alveolar pro- cesses; and about the fifth month ossification is perceptible • Serres, p. 3. DENTITION. 457 in the infant incisors, and goes on to the other teeth very much in the order of their appearance. The germs of the deciduous teeth are placed in an arc of a circle, the cuspidati being thrown forwards out of the line of the others and somewhat lower, in consequence of which the first molar border closely upon the incisors. The germs of the permanent teeth arc brought into view by removing the internal face of the jaw, and are at the posterior upper side of the first germs, being, therefore, nearer to the edges of the alveolar processes. At birth, ossification has taken place in all the infant teeth, though their roots are not yet completed. The rudiments of the permanent teeth, though seen at an early period of fatal existence, do not begin to ossify till after birth. Thus, the first adult incisor and molar begin to ossify about the fifth or sixth month of life, the second incisor and cuspidatus about the ninth month, the first bicuspis about the fifth year, the second bicuspis and second molar about the sixth or se- venth, and the third molar about the twelfth year.* Before the teeth protrude, a pedicle (Gubernaculum Dentis) passes from the alveolar end of the sac of the permanent tooth to the sac of the deciduous tooth; and even when the latter is fully formed and protruded, the same pedicle may be traced to that part of the gum surrounding the neck of the decidu- ous tooth.f At birth, the rudiments of fifty-two teeth may be found in the two jaws; and. as a general rule at that pe- riod, the rudiments of the permanent are more superficial than those df the deciduous; but their position is subsequently changed, so that the first descend while the latter ascend4 As the permanent teeth are preparing to protrude, the al- veolar cavities, in which they are contained, form orifices on the internal surface of the jaw near the edges of the deciduous alveolar processes. They arc called the Alveolo-dental Ca- • Hunter. f I. Cloquet, Anat. Pi. XXII. fig. 16,17. Serres, loc. cit. p. 109. t Serres. VOL. I.—3 M 458 ORGANS OF DIGESTION. nals, (Iter Dentis.) Those for the incisor and canine teeth are just behind their corresponding deciduous teeth, and those for the bicuspated near and somewhat behind the infant mo- lares. At this period, a bony septum separates almost com- pletely the two orders of alveolar cavities from each other. and thereby prevents their mutual interference. The permanent teeth being thus formed in new and distinct sockets, and being kept off from the deciduous, it is clear that the latter cannot be pushed out of their alveoli, as is sometimes supposed, by the growth of the former; and if it did take place, it would produce the great inconvenience of Causing them to rise up into the mouth, beyond the level of the other teeth. On the contrary, the deciduous teeth are made loose by the removal of their roots, which progresses till no- thing but the neck is left, and then the slightest force applied dislodges them from their position on the gum. This decay of the root is not even affected by the pressure of the rising tooth, for the new alveoli rise with the new teeth, and the old ones decay along with their decaying fangs; and when the first set falls out, the succeeding teeth are enclosed by a com- plete bony socket From which it is evident that the change is not produced by mechanical pressure, but is a particular process in the animal economy.* In further proof, however, Mr. Hunter has seen two or three jaws where the second deciduous grinders were shedding by the decay of their roots, without there being underneath any tooth to press upon them: and in another jaw he observed the same circumstance in both grinders. In a female patient, in whom the last temporary grinder was loose and was pulled out in consequence, it was not succeeded by another tooth. One of these patients, at the time, was aged twenty, and the other thirty; from which it would appear, that though the wasting of the fang of a deci- duous tooth does not depend upon the pressure of the perma- nent one, yet the latter determines, in some measure, its ex- pulsion, as without som such influence the period of shed- ding would not have been so late. • Hunter, loc. LRREGULARlTIES IN DENTITION. 459 In the lower jaw of the adult, there is but one arterial trunk, which supplies the teeth, but in the fcetus, till the age of six or seven, there are two arteries,* and as many canal9 for containing them. The lowest of these arteries belongs, exclusively, to the deciduous teeth; it is distinctly visible in the fcetus, augments till the third or fourth year, afterwards it shrinks, and is obliterated about the sixth or seventh year, In some rare cases its canal remains open for a longer time, as M. Serres has met with it in a woman of thirty. Being a branch from the inferior maxillary it enters the bone at a foramen somewhat lower down than the posterior maxillary, and what remains of it after the teeth are supplied comes out at another aperture a little below the anterior maxillary foramen, and there anastomoses with the other dental artery. M. Serres supposes that this artery, discovered by himself, and obviously serving in the evolution of the deciduous teeth, by being obliterated before they fall out, destroys their vita- lity, and therefore they become absolutely foreign bodies, the expulsion of which is required by nature on common principles. SECT. VI.—OF IRREGULARITIES IN DENTITION. The process in certain individuals is premature; Louis XIV. was born with two teeth ; many instances of the same sort of precocity are recorded by Haller, and other medical writers, in some of which, even ten teeth were found pro- truded at birth. On other occasions the process is retarded in a manner equally striking, and varying from the tenth month to the sixth or seventh year. This unusual tardiness is sometimes manifested in particular teeth ; thus I know a young gentle- man in whom one of the permanent incisors of the upper jaw did not come down before the fourteenth year. Borelh 'reports a woman in her sixtieth year, who never had teeth; * Serres, loc. cit. p. 17. 460 ORGANS OF DIGESTION. a magistrate of Frederickstadt lived to an advanced age, and never had either canine or incisor teeth; he was, however, furnished with molares. The teeth are sometimes supernumerary; it is not xevy uncommon to see this manifested by a single canine or inci- sor, and more frequently in the upper jaw than in the lower jaw. Occasionally there are several supernumerary teeth. Cases are recorded in which several teeth have been fused or joined together. Bernard Gengha reports, that in a pile of bones belonging to the Hospital S. Esprit, at Rome, he found a cranium in which there were.only three teeth ; in the two upper maxillae one occupied the space of all the incisors and the two cuspidati, and each of the others the space of all the molares of its respective side.* According to the historians Plutarch and Valerius Maximus; Pyrrhus king of Epirus, and Prusias king of Bithynia, had a single den- tal piece in each jaw, which stood in the place of the usual allowance of sixteen teeth. These cases are scarcely credi- ble, for the reason, that for them to have occurred, the mid- dle palate suture, which is slow in forming, and divides the germs of the two sides from each other, could not have ex- isted during the fatal state, at any time subsequent to the third month ; or what is more compatible with this account, at no time whatever. It is more probable, therefore, that notwithstanding the royal opportunities of cleanliness pos- sessed by these persons, their teeth were neglected, and per- mitted to incrust themselves with a dense, thick coat of tartar, which gave them the appearance of a single piece : a circum- stance which occurred to Sabatier, in a girl of fifteen or sixteen, and to Fournier jn an individual of the same age and sex.f Another objection is, that as the common law of the germs is to develop themselves, and to ossify at different epochs, in these two cases they were all not only proceeding at the same rate, but also joining one another, so as to form but a common sac, confounding, thereby, all the known phe- nomena of dentition. * Sabatier, Anat. tome I. p. 78. f Diet, des Sc. Med IRREGULARITIES IN DENTITION. 461 In most persons there are but two sets of teeth; it has happened, however, in several instances, for people about the age of seventy to have one or more new teeth belonging to a third set; they are commonly incisors. J. Hunter saw an example of the kind.* The Countess of Desmond, who lived to her hundred and fortieth year, had, at this period, according to Bacon, a third set of teeth.f Mentzelius nar- rates a similar case^: in the following w7ords. " Having ac- companied the Elector of Brandenbourg on a visit to Cleves, in 1666, there arrived, at the same time, a man aged one hundred and twenty, who exhibited himself for money, and whom I saw at the court of the Elector. His strength of voice manifested that of his breast, and he having ran over the gamut, was heard at more than a hundred paces off. Having then opened bis mouth, he showed us two rows of pearly teeth, and on the subject of their beauty related 'that being at the Hague twTo years before, on the same errand which brought him to Cleves, there arrived an Englishman, aged one hundred and twenty; that he visited the latter, and addressed him in the following terms. * We are nearly of the same age, for I am only two years younger than you, and I have had the greatest desire to see one older than myself, for I have felt no inconvenience till lately; but during the three days that I have been here, I have had severe headache and dreadful pains in the jaws, which convince me that 1 am about to die.' 'You are mistaken, my dear friend,' says he to me, « on the contrary, you are becoming younger, for you are about to teeth again like an infant.' 'Oh !' answered I, 'I pray to God not to punish me by prolonging my days.' I left him then and went to bed, and immediately after felt the most excruciating pains in the jaws, which were followed by the eruption of the teeth that you now see.'" The circumstance of a third dentition, has given rise to a question among physiologists, whether the germs are prima- * Loc. cit. p. 85. f Hist. vit. et. mort. Col. 5.36. $ Serres, loc. cit. p. 40. 462 ORGANS OF DIGESTION rily supernumerary ? or whether the gums have within them- selves organs capable of forming and of producing new teeth ? When such teeth come out in a straggling manner, they hurt the opposite jaw, and have to he extracted. In old persons who have lost all their teeth, there is a car- tilaginous hardening of the gum, as in infancy, whereby they still retain some power of mastication. When the body of the tooth has been worn away, nature prevents the exposure of its cavity by the deposite of new matter, which may be known by its darker colour, and by its transparency. The muscles of mastication are, the Temporalis, the Mas- seter, the Pterygoideus Internus, and the Pterygoideus Ex- ternus. CHAPTER III. OF THE TONGUE. The Tongue (Lingua) is the principal organ of taste, and is also concerned in mastication and in speech. It is an ob- long, flattened, muscular body, which extends from the os hyoides posteriorly to the incisor teeth anteriorly, and, being placed at the bottom of the mouth, fills up the space within the two sides of the body of the lower jaw. The exact ex- tent of room which it occupies, varies according to its being in a state of repose or of activity. The posterior extremity of the tongue is called its base, and arises muscular from the body and the cornua of the os hyoides ; it is there considerably thinner than elsewhere. Its MUSCLES OF TONGUE. 463 anterior extremity is called the tip or point, is loose, and has a rounded thin termination. Between the point and the base is the body. The superior surface of the tongue is flat, is divided by a middle longitudinal fissure of inconsiderable depth into two equal parts, and is covered by the lining mem- brane of the mouth, under a particular modification of struc- ture. The inferior surface of the tongue with the exception of its middle part, is also free, and covered by the common mucous membrane of the mouth, but the latter is there very thin, and the veins may be readily seen shining through it. SECT. I.—MUSCLES OF TONGUE. The muscles which compose the principal part of the bulk of the tongue are, the Stylo-glossus ; the Hyo-glossus; the Genio-hyo-glossus; and the Lingualis. As these, besides belonging to the general muscular system, also form so im- portant a part of this organ, with the view of collecting the account of its structure, their description will be repeated. 1. The Stylo-glossus arises from the styloid process of the temporal bone, and soon reaches the side of the base of the tongue. Some of its fibres extend to the tip and confound themselves along with those of the superficial lingual muscle, above and below the margin of the tongue, while others form a broad transverse fasciculus, which is united to the corres- ponding portion of the other side. 2. The Hyo-glossus arises from the side of the base of the os hyoides, from its cornua, and from its appendix in a slight degree. It is placed within the stylo-glossus and extends forwards toward the tip of the tongue. Some of its fibres go as far as the middle of the tongue ; others rise almost per- pendicularly upwards to its base ; while the remainder are confounded, along the margin of the tongue, with the super- ficial lingual muscle. 161 ORGANS OF DIGESTION. 3. The Genio-hyo-glossus arises from the tubercle on the posterior face of the symphysis of the lower jaw, and imme- diately after its origin spreads itself after the manner of a fan. Its inferior fibres are inserted into the base of the os hyoides, while the remainder, by their diverging, are insert- ed into the whole length of the tongue from its base to its point. This muscle is in contact, side by side, with its fel- low, and there is a sort of fissure with a small quantity of adipose matter between them. As the fibres of this muscle go from below upwards they penetrate to the upper surface of the tongue, and, consequent- ly, traverse the transverse lingual muscle and the superficial lingual. 4. The Lingual is is a small narrow fasciculus of fibres, which arises indistinctly about the root of the tongue, in the yellow tissue there, and advances to the tip between the hyo- glossus and the genio-hyo-glossus. The lingual surface of the lining membrane of the mouth, on the upper surface of the tongue, is somewhat cartilagi- nous, and into it is inserted many of the subjacent muscular fibres. At the base of the tongue this cartilaginous condition is deficient, and its place is supplied by a yellow tissue which adheres to the os hyoides, to the epiglottis, and to many mus- cular fibres below, and has in it mucous follicles. 5. The Superficial Lingual Muscle is abroad thin layer, co- vering the upper surface of the tongue, below the mucous membrane ; it begins behind, on a line with the greater pa- pillae, and advances forwards to the tip. Its more internal fibres converge and end at the middle line, but the external ones terminate above and below near the margin of the tongue. 6. The Transverse Lingual Muscles consist in scattered small fasciculi, which are placed below the last, and in the thickness of the tongue, which they traverse at right angles. One end of them, on each side, ceases at the middle line of the PAPILLARY STRUCTURE OF TONGUE. 465 tongue, where there is a small seam, and the other end ter- minates in the membrane of the tongue, at the margin of this organ. These fibres are to be found in the whole length of the tongue, and gradually become more curved at its base. 7. The Vertical Lingual Muscles extend from the upper to the under membrane of the tongue. They consist in small scattered fasciculi, like the preceding, and cross them at right angles in traversing the thickness of the tongue.* SECT. II.—PAPILLARY STRUCTURE OF TONGUE. The mucous membrane of the mouth, where it forms the franum linguae, is over the anterior margin of the genio-hyo- glossus muscles: the same membrane, in going from the base of the tongue to the epiglottis and forming another franum, has, on each side Of it, a depression or pouch in which arti- cles of food sometimes lodge. Beneath the last franum is a ligamentous tissue which runs to the base of the tongue from the front of the epiglottis, and serves to keep the latter erect; some muscular fibres are occasionally Seen in this tissue in the human subject, and in the black bear of N. America it consists in a pair of strong muscles. The pouch on each side is bordered, externally, by a more superficial doubling of the mucous membrane, which passes from the base of the tongue to the side of the epiglottis. As observed, the mucous membrane, on the under surface of the tongue, offers no peculiarity of organization : but, on the upper surface, it is remarkable for the unusual size and development of its papilla, for having its epidermis easily de- tached, and also for having the muscular structure beneath so closely attached to it. • The preceding 'views of the minute muscular structure of the tongue have lately been advanced by M. Gerdy, of Paris. See J. Cloquet, Anat. De L'Homme, pi. CXIX. CXX. J. F. Meckel, loc cit. Note des tradus- teurs, vol. HI. p- 313. VOL. I.—3 N 466 ORGANS OF DIGESTION. The anterior two thirds of the upper surface of the tongue is entirely covered by these papilla. They are so thickly set as to touch one another, and, as they present some pecu- liarities of form, they are divided into Papilla Maxima or Capitata, Media, Villosa, and Filiformes. The Papilla Maxima constitute the posterior border of the papillary surface of the tongue, and are about nine in number, though they are frequently fewer and sometimes more. They are disposed in two oblique rows, which, by converging backwards, meet and form something like the letter V. Each of these bodies resembles a cone standing upon its summit, and is surrounded by a circular fossa which permits it to project but inconsiderably above the general level of the tongue. Sometimes two or more are in the same fossa. The Papilla Media or Fungiformes are more nume- rous than the last and next to them in size, they are enlarged at their loose end into a sort of rounded head, whence their name; they are irregularly scattered over the tongue. Those which are next in size and still more abundant, are the Pa- pilla Villosa. The Papilla Filiformes fill up the interval* of the others, are the smallest, and arc found principally near the middle of the tongue and at its front extremity. Most commonly the papilla maxima are so disposed that the central one is the point of the letter V. It has the largest fossa of any, which is designated by the term fora- men cacum, and a little behind this foramen there is fre- quently another, but not furnished with a papilla, into which mucous follicles discharge their contents, and which from time to time has been considered as receiving the excretory duct of the thyroid, or of some of the salivary glands. The papilla of the tongue, though they vary in their shape and size, have very much the same structure in regard to the abundance of blood vessels and nerves which enter into their composition. When uninjected, and viewed with the naked eye, their surface appears smooth, but when made tur- gid by injection, it is covered with little asperities or fila- ments, which seem to be formed principally of blood vessels, having a very tortuous and superficial course, forming dou- PAPILLARY STRUCTURE OF TONGUE. 45"J blings in projecting on the surface of the papilla, and anas- tomosing freely with each other.* Besides vessels, there is a soft whitish substance, supposed to be nervous, entering into the Composition of each filament. The larger papilla on the back part of the tongue are supplied by the glosso- pharyngeal nerve, and the papilla on its front part by the trigeminus or fifth pair. The surface of the tongue between the papilla maxima and the os hyoides is destitute of such papilla, and is covered with the common mucous membrane of the mouth, having beneath it many muciparous glands, which in different individuals produce prominences more or less elevated. The Epidermis, which is found upon all other parts of the lining membrane of the mouth, is also continued over the whole upper surface of the tongue, and consequently invests each papilla, it is called there Periglottis. • It is soft and humid, may be detached by maceration, and is frequently de- tached in fevers. On its upper surface, it when detached, will have many elevations, while on the lower there will be cor- responding projections, which to superficial observation give it the appearance of being cribriform. The Tongue is supplied with arteries, principally from the lingual branch of the carotid, and with nerves from the hypoglossal, the fifth pair, and the glosso-pharyngeal. The former is supposed to be exclusively appropriated to its mus- cular movements, and the two latter to its sensations. Its faculty of taste seems to be most active at the tip; on the sides, and near the middle behind, it is inconsiderable. The soft palate seems also to participate in the function of taste. • Soemmering, Anat. J. Cloquet, Anat. Pi. cxix. 468 ORGANS OF DIGESTION. CHAPTER IV. OF THE PALATE. The Palate (Palatum) is composed at its anterior part of the palatine processes of the superior maxillary and pala- tine bones, covered above by the pituitary membrane, and below by the lining membrane of the mouth. This portion of it is the hard palate, and separates the mouth from the nose. Behind it is a membranous portion called the soft pa- late, which separates partially the mouth from the upper part of the pharynx. That part of the lining membrane of the mouth which contributes to the hard palate, has a bard cartilaginous feel, and is not so vascular or sensible as other parts. It has a ridge in its centre just beneath the middle palate suture, and from each side of it there are transverse ridges extending to the alveolar processes. This arrangement is more evident at its anterior part, and in middle aged persons; in the old it is faint, and frequently does not exist when the alveoli are gone. Beneath this membrane, particularly at its posterior part, the muciparous glands are very abundant and closely set against each other. The Soft Palate ( Velum Pendulum Palati) has an oblong shape, and being a continuation of the posterior margin of the hard palate, it is stretched across the back of the mouth from one side to the other, and obliquely downwards and backwards. • Its inferior margin, which is free, offers in its centre a projection of half an inch or three quarters in length, which is the Uvula. From each side of the latter there proceed two crescentic doublings of the lining mem- brane of the mouth, called the lateral half arches of the pa- late. The Anterior Half Arch is more distinct than the other, THE PALATE. 469 and arising at the side of the uvula by one end, terminates by the other in the side of the root of the tongue. The Posterior Half Arch arises from the side of the uvula near the last, and diverging from it backwards and outwards, has the other end lost gradually in the lining membrane of the pharynx near its middle. In the depression between these duplications, on either side, is the Tonsil Gland. The space bounded in front and behind by these lateral half arches is the Fauces, and the anterior opening into it is the Isthmus of the Fauces. When the mucous membrane of the soft palate is removed, its muscles are exposed and are as follow: 1. The Constrictor Isthmi Faucium is a small fasciculus of fibres, on each side, within the duplicature of the anterior lateral half arch. It arises from the side of the tongue near its root, and is inserted into the middle of the soft palate near the root of the uvula. It tends to close the opening between the mouth and the pharynx. 2. The Palato-Pharyngeus is also a small fasciculus with- in the duplicature forming the posterior lateral half arch. It arises from the middle of the soft palate near the root of the uvula, and is inserted into the pharynx between the middle and lower constrictors, and into the superior posterior mar- gin of the thyroid cartilage. It draws the soft palate downwards. 3. The Circumflexus, or Tensor Palati, is behind the pte- rygoid process of the sphenoid bone. It arises from the spi- nous process of the latter behind the foramen ovale, and from the contiguous part of the Eustachian tube; it then passes downwards in contact with the pterygoideus internus muscle, and terminates in abroad tendon below, which winds around the hook of the internal pterygoid process, and is inserted into the soft palate near its middle, and into the posterior lunated edge of the palate bone. 170 OKI.ANS OF DIGESTION It spreads out or extends the palate. 4. The Levator Palati is on the inner side of the last It arises from the point of the petrous bone, and from the con- tiguous part of the Eustachian tube, and passes downwards to be inserted into the soft palate. It draws the soft palate upwards. 5. The Azygos Uvula is in the centre of the soft palate and of the uvula. It arises from the posterior pointed termina- tion of the middle palate suture, and goes down to the point of the uvula. It draws the uvula upwards, and diminishes the vertical breadth of the soft palate. When the mucous membrane is removed, the upper con- strictor of the pharynx appears between the anterior and the posterior half arches. CHAPTER V. OF THE GLANDS OF THE MOUTH! These glands consist in such as are muciparous, and in such as are salivary. SECT. I.—MUCIFAROUS GLANDS. These glands (Glandulse Muciparae) are whitish, some- what oval and flattened, and are from the fraction of a line to two lines in diameter; they are found in great abundance beneath the lining membrane of the mouth at several places, to wit: on the lips, (Gland. Labiales); on the cheeks, (Gland. Buccales); and also, as mentioned, at the posterior part of SALIVARY GLANDS. 471 the upper surface of the tongue, (Gland. Mucip. Lingua.) The layer of them, (Gland. Palatina,) which is found at the posterior part of the hard palate, is also continued over the anterior and the posterior surface of the soft palate, especially the latter surface. The Tonsils, (Tonsillas, Amygdalae,) situated, as observ- ed, one on each side, between the arches of the palate, are six or eight lines long, three or four wide, and as many thick. They are rather a collection of large mucous follicles, than a congeries of glandular bodies, in consequence of which their surface is very much reticulated. Owing to their being based upon the upper constrictor of the pharynx, their mo- bility is very striking and considerable. A great many small pores are observed on the internal surface of the mouth, which arc the orifices of the ducts of the muciparous glands. SECT. II.—SALIVARY GLANDS. On either side of the neck, bordering upon the mouth, there are three glandular bodies for the secretion of saliva; they are the parotid, the submaxillary, and the sublingual. The fluid secreted from them is of great service in digestion, and is blended with the food in mastication, and in swallowing. According to Bcrzelius, it has a considerable affinity to oxy- gen ; and consists in a white mucous substance, having, in a state of solution, the saline articles usually found in the se- rum of the blood. The Parotid Gland, (Glandula Parotis,) is the largest of the three, and, like the others, is of a light pink colour. Its form, owing to the space into which it is crowded, is of a very irregular figure. It fills up the cavity on the side of the cranium between the mastoid process and the ramus of the lower jaw, extending beyond the edge of the latter so as to cover the posterior margin of the masseter muscle. It is somewhat pointed at its fore part. Its vertical length reaches 472 ORGANS OF DIGESTION. from the zygoma above, to the angle of the jaw below; some- times, indeed, a little lower down. In thickness it extends from the integuments externally, to the styloid process, the styloid muscles, and the tendon of the digastricus internally, being there only separated from the internal carotid artery by these parts. It is traversed from behind forwards by the portio-dura nerve, and from below upwards by the external carotid artery and the temporal vein. This gland has no appropriate capsule, but being covered on its external face by the continuation of the fascia superfi- cialis of the neck, prolongations are sent from the fascia which penetrate it in every direction, and keep its lobules together. Its duct (Ductus Stenonianus) departs from its anterior edge a few lines below the zygoma, and traverses the outer face of the masseter muscle, in a line, according to the obser- vations of Dr. Physick, drawn from the lobe of the ear to the end of the nose. It is about the size of a crowr quill, is hard and tendinous, with thick parietes. It lies close to the masseter muscle, and at the anterior edge of the latter penetrates a pad of fat commonly found there on the side of the cheek; it then perforates the posterior end of the buccinator, so as to have its oral orifice opposite the second large molar tooth of the upper jaw. On opening the mouth wide during a state of fasting, a jet of saliva will sometimes indicate the position of this orifice. A small gland (Gland. Accessoria Parotis) is sometimes found betw een this duct and the zygoma; it varies in form and size, and has a distinct excretory canal discharging itself into the parotid duct. The Submaxillary Gland (Glandula Submaxillaris) is not more than a third or one half the size of the last and has a more regular form, in being somewhat ovoidal. It is accom- modated in the depression on the side of the neck formed by the body of the lower jaw externally, by the mylo-hyoideus muscle above, and by the tendon of the digastric below. The platysma myoides intervenes between it and the skin. It SALIVARY GLANDS. 473 almost touches the parotid gland behind, being separated from it only by a process sent in from the fascia superficialis, and continuous with the ligament going from the styloid pro- cess to the ramus of the lower jaw. As it extends to the pos- terior margin of the mylo-hyoideus muscle, it there touches the sublingual gland. The facial artery either passes through it or is very much connected with it Its colour and appearance are the same with the parotid, but its lobules are more easily separated, as they are held toge- ther only by weak cellular substance, which forms a sort of capsule to them. Its duct, (Ductus Whartonianus,) which is single, comes from the assembling and junction of branches from the several lobes. It is much thinner, more extensible, and larger in proportion than the parotid duct; and being directed backwards, winds over the posterior edge of the mylo-hyoid muscle, in order to get to the cavity of the mouth. It then passes along the internal face of the sublingual gland, below the tongue, and terminates by a small projecting ori- fice on the anterior margin of the franum lingua. A continuation of the substance of this gland, of a few lines in thickness, described by Bartholin, is found at the poste- rior end of the sublingual gland, and has its excretory duct sometimes opening into the duct of Wharton, and on other occasions into one of the ducts which issue from the sublin- gual gland. The Sublingual Gland (Glandula Sublingualis) is an ob- long body, covered by the lining membrane of the mouth, but visible when the tongue is turned up. It is placed above the mylo-hyoid muscle, along the under surface of the tongue, and is readily distinguished by its ridged unequal surface, project- ing into the mouth. It is not so large as the submaxillary § Its lobules are smaller than those of the preceding gland, and are also whiter and harder. Instead of having but one excretory duct it has several; sometimes fifteen or twenty of them are discernible; on other occasions, several of them are collected into one or two principal trunks, and open either vol. I.—3 o 474 ORGANS OF DIGESTION. directly into the mouth, or into the duct of Wharton. These several openings are found along the bottom of the mouth, on either side, below the tongue. Several small salivary granu- lations or glands border on the sublingual. The position of the salivary glands is such, that they are much moved and pressed upon by the neighbouring parts in mastication, independently of the emission of their fluid being provoked by hunger. Owing to the similitude of their structure, and to their not being regularly supplied like other glands with capsules, their limits are occasionally so inex- actly traced, that they continue into each other by adjacent points, and form thus an uninterrupted chain.* They all are of the conglomerate kind, or, in other words, consist in a congeries of smaller glands or lobes and lobules. They are well furnished with arteries, which are branches from the external carotid, and go in several trunks instead of in a leading one. The parotid is commonly supplied by trunks coming directly from the external carotid, the sub- maxillary is supplied from the facial artery, and the sublin- gual gland from the lingual artery. Their nerves come from the fifth pair, and from the portio dura. The retrograde injection of their excretory ducts shows how the latter are formed by the assembling of branches from the different lobules. These ducts consist of two coats, a fibrous one externally, and a mucous one internally. • Bichat, Anat. Descrip. vol. v. p. 24. THE PHARYNX. 475 CHAPTER VI. OF THE PHARYNX AND CESOPHAGUS SECT. I.--OF THE PHARYNX. The Pharynx (Pharynx) is a large membranous cavity, placed between the cervical vertebra and the posterior part of the nose and mouth. It extends from the base of the cra- nium to the lower part of the cricoid cartilage, or to the lower part of the fifth cervical vertebra. It is in contact, behind, with the vertebra and the muscles lying upon them, being simply attached there by loose cellular substance; above it adheres to the cuneiform process of the os occipitis, and to the points of the petrous portions of the temporal bones ; in front to the posterior margin of the upper and of the lower jaw, to the cornua of the os hyoides, the side of the thyroid and of the cricoid cartilage; and below it is continued into the oeso- phagus. In consequence of these several attachments the pharynx is kept open, or, in other words, its sides are pre- vented from collapsing, and it is drawn up and down in the motions of the tongue and of the larynx. The Pharynx consists in three coats; an external one formed by three muscles, on each side, one above the other, and called constrictors; an intermediate cellular coat; and an internal mucous one. 1. TheMusculus Constrictor Pharyngis Inferior, arises from the side of the cricoid, and from the whole length of the side of the thyroid cartilage. From these points its fibres diverge to the middle vertical line on the back of the pha- rynx, where they join with their congeners of the opposite side. The lower fibres are nearly if not completely horizon- tal, and those above increase successively in their obliquity upwards, so that the upper ones are extremely oblique, and reach at their termination to within twelve or fourteen lines -of the upper part of the pharynx. 476 ORGANS OF DIGESTION 2. The Constrictor Pharyngis Medius arises from the cornu and appendix of the os hyoides, and from the ligament connecting the posterior end of the latter with the upper cornu of the thyroid cartilage. Its inferior margin is over- lapped by the superior margin of the last; its fibres there are also horizontal, and, indeed, somewhat convex down- wards, while the superior fibres become successively more oblique in ascending. It is inserted by the middle line be- hind, into its fellow of the opposite side, and by its point above into the cuneiform process of the os occipitis, just in advance of the foramen magnum. 3. The Constrictor Pharyngis Inferior arises from the cuneiform process of the os occipitis, from the pterygoid pro- cess of the sphenoid bone, and from the back part of the upper and under jaws behind the last molar teeth. It is con- nected at its anterior margin with the root of the tongue, and with the buccinator muscle. It has its lower edge over- lapped by the last, and is inserted into its fellow by the mid- dle line on its posterior part. Its fibres are more horizontal generally than those of the preceding muscles. The constrictor muscles of the pharynx, by their successive contraction, convey the food from the mouth into the oeso- phagus. The Stylo-Pharyngeus, which is mentioned among the muscles of the neck, forms an interesting portion of the struc- ture of the pharynx, and may be considered on a footing with the longitudinal fibres of the oesophagus and of the in- testines; being intended to shorten the pharynx by arising from, or having a fixed point at the styloid process above, and by being joined into the pharynx below. Its fibres being first of all on the outside of the upper constrictor, are readily traced between the lining membrane and the two lower con- strictors to the posterior margin of the thyroid cartilage, into which, after spreading out considerably, they are finally inserted. (ESOPHAGUS. 47 7 The intermediate membrane of the pharynx is merely con- densed cellular tissue, which joins the muscular to the mu- cous coat. The Internal or mucous membrane of the pharynx, which lines the last, is spread uniformly over it; the only irregu- larity of its surface being made by the presence of mucous follicles, which are more abundant above than below. It is covered by a very delicate epidermis. Is supplied with two arteries on each side, the superior and the inferior pharyn- geal, the first of which comes from the internal maxillary and the second from the external carotid, and exhibits a number of small veins, which run into the internal jugular or some of its branches. The shape of the cavity of the pharynx is oblong and cylin- drical, being somewhat larger at its superior end; at the latter place, where it is attached to the petrous bone, it pre- sents a deep corner, which gives it a square appearance there. Anteriorly and above it is continuous with the Eu- stachian Tubes, and with the posterior nares, just below this with the fauces and mouth, and below the root of the tongue with the cavity of the glottis or larynx. At its lower extremity where it terminates in the oesophagus it is con- tracted so as to suit the size of the latter cavity. SECT. II.—OF THE OESOPHAGUS. The oesophagus is the tube just in front of the spine and behind the trachea, which conducts food from the pharynx into the stomach. When inflated it is of a cylindrical shape, gradually increasing, however, in its size from above down- wards, but in its state of repose it is flattened from before backwards. Its descent is not entirely vertical, but at the lower part of the neck it inclines somewhat to the left of the middle line, and is therefore rather to the left side of the tra- chea than behind it. It passes down the thorax in the poste- 478 ORGANS OF DIGESTION rior mediastinum, being bounded on its left sideby the aorta, and on the right by the vena azygos. It keeps during the early part of its course in this cavity, in front of the middle line of the spine, hut lower down it inclines again slightly to the left side in front of the aorta, in order to reach the oesophageal orifice of the diaphragm, through which it penetrates into the abdomen. In all this passage the oeso- phagus is united to adjacent parts by a loose cellular tissue. The oesophagus is composed of three coats, the muscular, the cellular or nervous, and the mucous. The muscular coat is the external, and very strong. It consists in two well marked lamina of muscular fibres. The most exterior is the thickest, and goes longitudinally from one end to the other of the tube; commencing, according to J. F. Meckel, by three fasciculi above, one of which arises tendinously from the posterior face of the cricoid cartilage, and the other two, one on each side, from the inferior con- strictor of the pharynx. These fasciculi descend for an inch or two before they spread out into an uniform membrane. The internal muscular lamina consists in circular fibres, which may be considered as a continuation of the lower margin of the inferior constrictor of the pharynx ; these fibres are rather deficient on the fore part of the oesophagus for an inch at its superior extremity. The cellular coat is next in order, and serves to unite the muscular and the mucous together. It adheres much more closely to the latter than it does to the former, has no adipose matter in it, but is said to be abundantly furnished, more particularly towards its upper end, with small muciparous glands ; it also serves to transmit the blood vessels through the structure of the oesophagus. The mucous coat of the oesophagus is the most internal; in the undistended state it always presents many longitu- dinal folds, going from one end to the other, but sometimes blending with each other; and owing to the contraction of CESOPHAGUS. 479 the circular muscular fibres. When suspended in water its fine villous appearance is very perceptible, as well as the mucous lacuna or glands which open upon its internal sur- face. As it is a continuation of the mucous membrane of the pharynx, it has the same general appearance but is rather whiter. Its internal surface is also covered by a delicate epidermis, which ceases at the cardiac orifice of the stomach, and may be raised in shreds by maceration and by boiling; in some pathological conditions it becomes very distinct by acquiring more thickness and solidity, than what belong to its healthy state. The arteries of fhe oesophagus are derived from the in- ferior thyroidal, from the thoracic aorta, and from the gas- tric. Its nerves come principally from the pneumogastric. * END OF VOL. I INDEX TO VOL. I. Page Abductor Indicis Manus,......401 Minimi Digiti Manus,.....401 — — Pedis,.....433 Pollicis Manus,......399 Adductor Brevis,........415 Longus,......" 415 Magnus, ------- 416 Metacarpi Minimi Digiti, - 402 Pollicis Manus, -.....401 Adeps,.......- - " 29° Anconaeus,.........s°' Ankle Joint, - ,........256 Aponeurosis Plantaris,.......410 Arm,....... - ™ Astragalus,........- 236 Azygos Uvulae,........4' ® Biceps Flexor Cruris,.......420 — Cubiti,.......384 Bones individually, and their Articulations, 41 Composition of,..... ' Development of,..... x* General Anatomy of, - QQfJ Brachialis Internus,..... - - - - 375 Buccinator, - Callus, Formation of, - " Carpal Bones, Articulation between the two rows of, 206 Carpo-Metacarpal Articulations,.....208 _ ««---- 185 Carpus, - Cartilages, Accidental Development of, - - - - •>" Articular, - - *2 VOL. I.—3 P 482 1N*EX- Page Cartilaginous System,.....Vol. I. 28 Cellular Substance,.......28! Cervicalis Descendens, - - - - - - - 536 Cervical Vertebrae generally, - - - - - 45 individually, ----- 46 Cheek Bones,........129 Circumflexus, or Tensor Palati, ----- 469 Clavicle,.........178 Coccyx, or Caudal Vertebra, - - ' - - - 53 Complexus,.........337 Compressor Naris,.......372 Constrictor Isthmi Faucium, .....469 Pharyngis Inferior, ... - - 475 — Medius,.....476 — Superior,.....476 Coraco Brachialis, ------- 385 Cranium,.........106 Diploic Structure of,.....145 Individual Bones of,.....108 Cremaster, -.......- 348 Cruraeus, -.....- - " 413 Cuboides, --......" 238 Cuneiforme Externum,.......239 Internum,.......238 Medium,.......239 or Pyramidale,......186 Cuticle, -........301 Cutis Vera,.........295 Deltoides,.........381 Dentition,.........454 Irregularities in,......459 Depressor Anguli Oris, ------- 3/75 Labii Inferioris,......375 Labii Superioris et Ala .Nasi, - 374 Dermoid Covering,.......293 Diaphragm,.........352 Digastricus, --------- 367 Dorsal Vertebra,........48 individually,.....49 Elbow Joint,........201 index. 483 Page Ethmoid Bone,......Vol. I. 120 Extensor Brevis Digitorum Pedis,.....430 Carpi Radialis Brevior,.....394 — — Longior,.....394 — Ulnaris,......395 Digitorum Communis, ----- 395 Longus Digitorum Pedis, - 423 Major Pollicis Manus, - 397 Minor Pollicis Manus,.....397 Ossis Metacarpi Pollicis Manus, - 396 Pioprius Pollicis Pedis,.....424 External Surface of the Head,.....151 Extremities, Lower, Articulations of, 246 — Development of, 263 — General Motions of, - 276 — Mechanism of, in regard to Locomotion, 271 — — — Standing, 265 Upper, Articulations of, 193 — Development of, 212 — Mechanism of, - 214 Face,...........123 together with some remarks on the Facial Angle, and on National Peculiarities, .... 150 Fasciae of the Foot,.......410 Fascia Cruralis,.......- 408 Iliaca, --......358 Lata Femoris,.......405 of Lower Extremities, - - - - - 405 Profunda Colli,.......364 Superficialis Colli, - - - - - - 662 Transversalis Abdominis,.....349 of Upper Extremity,......37"8 Fibro, or Ligamento-Cartilaginous System, 33 Fibula, -........231 Flexor Accessorius, -......431 Brevis Digitorum Pedis,.....431 __ Minimi Digiti Pedis, - 433 __ Pollicis Manus,.....400 — — Pedis,.....432 Longus Digitorum Pedis Perforans, - - - 423 484 INDEX. Page Flexor Digitorum Profundus Perforans, - Vol. I 390 — Sublimis Perforatus, - 389 Longus Pollicis Manus, ----- 391 — — Pedis,.....429 Manus, vel Carpi Radialis, ----- 388 — — Ulnaris,.....389 Parvus Minimi Digiti Manus, ... - 401 Fontanels,.........170 Foot,..........234 Articulations of,.......257 Motions of,.....,.- 275 Fore-Arm, '.......- - 181 Motions of,.......217 Frontal Bone,........108 Gastrocnemius, -------- 426 Gemini, --.......418 General Anatomy of Cellular Substance, ... 281 Bones, -.....7 Ligamentous or Desmoid Tissue, - 34 Cartilaginous Tissue, - - - 29 Fibro-Cartilaginous Tissue, - - 33 Muscular Tissue, - - - - 315 Dermoid Tissue, or Skin, - - 293 Adipose Tissue, - 290 Glutaeus Magnus, .......416 Medius,........417 Minimus,.....- - 418 Genio-Hyo-Glossus,.......464 Hyoideus, - ......369 Gracilis,.........414 Gums,.........4-**448 Hairs,.........- 310 Hand,..........185 Motions of,........220 Partial Motions of,......221 Head, - ........106 General Considerations of, - 138 External Surface of,......151 Foetal, Development of, - - - - - 169 Hyo-Glossus,........463 index. 485 Page Iliacus Internus,......Vol. I. 357 llio-Femoral, or Hip Articulation, ... - 246 Ilium, - - '........71 Indicator,.........398 Inferior Extremities, -......224 Spongy Bones,......- 131 Infra-Spinatus Scapulae,......383 Integuments of the Body,......281 Intercostales,........ 361 Internal Surface of the Cranium,.....147 Interosseus Digiti Auricularis, - - - - - 403 — Minimi Pedis,.....436 Primus Digiti Primi, or the Abductor Indicis Pedis,.......434 Primus Digiti Tertii, or the Abductor Tertii Digiti Pedis,......435 Primus Secundi Digiti Pedis, or the Abductor Medii Digiti,......435 Secundus, Digiti Secundi, or the Adductor Medii Digiti,......435 Secundus, Digiti Tertii, or the Adductor Tertii Digiti,......435 Secundus, Primi Digiti or the Adductor Indi- cis Pedis,......434 Interspinals,........340 Intertransversarii,.......340 Ischium,...... - 74 Jaw, Lower, Articulation of,.....135 Joints, Ligaments off.......37 Joint, Shoulder, Motions of,......215 • Knee,........249 Latissimus Dorsi, - - - - Leg, -----.....228 Motions of,...... " 274 Levator Anguli Oris, - - - - - 373 Levatores Costarum, - - - - - 341 Levator Labii Inferioris,......375 — Superioris et Alae Nasi, - - - - 373 Palati, ^........470 Scapulae,........334 480 1NUEi- Page Ligamentous or Desmoid Tissue, - - - Vol. I 34 Ligamentum Annulare of Ankle Joint, - 409 Lingualis,....._.-- 464 Lips,..........439 Longissimus Dorsi,.......335 Longus Colli,.....- - - 370 Lower Jaw, - - - - - - - - -132 Radio-Ulnar Articulation,.....204 Lumbricales Manus, - --.....399 Pedis,.......432 Lunare, ...-.....186 Magnum,.......- - 188 Manner in which the Bones grow, - - - - - 22 Masseter,.........375 Medulla, and its Membrane called the Internal Perios- teum, 16 Metacarpo-Phalangial Articulations, - - - - 210 Metacarpus, .,------ 190 Metatarsal Articulations,......262 Metatarsus,.........240 Mouth,.........438 Glands of,.......470 Muciparous Glands,.......270 Muscles, General Anatomy of,.....315 and Fasciae of the Abdomen, - - - - 341 of the Arm,.....- - 384 Face,.......372 Foot,.......430 Fore-Arm,.....- " 388 Front of the Thorax, - - - - 359 Hand,.......399 Leg,.......422 Neck,.......362 Posterior Face of the Trunk, - - 330 Thigh,.......411 Tongue,......463 Trunk, - --- - 330 Shoulder,......381 Upper and Posterior Parietes of the Abdo- men,......«*3-' index. 487 Page Muscular Motion,......Vol. I. 330 Mylo-Hyoideus,........369 Nails,..........307 Nasal Bones,........i28 Cavities,........155 CEsophagus, - .....477 Obliquus Capitis Inferior,......340 — Superior,......340 Externus,.......343 Internus,.......S45 Obturator Externus,.......420 Internus,.......419 Occipital Bone,........U2 Occipito-Frontalis,........372 Omo-Hyoideus, - -......36r Opponens Pollicis,.......400 Orbicularis Oris,........37^ Palpebrarum,......373 Orbits of the Eyes,.......15J Organs of Digestion, ----- - 437 Mastication and Deglutition, - - - - 438 Os Calcis,..... Os Hyoides, ------ Ossa Innominata, - Osteogeny, - " - - 468 Palate' " ' 125 Palate Bones, - - Palato-Pharyngeus, - - " 3gg Paltnaris Brevis, - -389 Longus, - - ] 111 Parietal Bones, - - * _ ^ Parotid Gland, - - - 233 Patella, - ... 415 Pectinalis, - _ _ S5g Pectoralis Major, - - 1 360 Minor, - Pelvic Vertebrae, - - ' Pelvis, Articulations of, - - - Development of,..... Difference of, in the Male and Female, - - 78 488 INDEX. Page Pelvis Generally,.....- Vol. I. 76 Mechanism of,......- 85 Perichondrium, --......31 Periosteum,.......- - 14 Peroneo-Tibial Articulation, -.....354 Peroneus Brevis,........425 Longus,........425 Tertius,........424 Pisiforme,.........186 Phalanges,.........192 Phalangial Articulations,......211 Pharynx,.........475 Plantaris,.........427 Platysma Myoides,.......363 Ploughshare, - - - - - - - - -131 Popliteus,........^ - 428 Posterior Annularis,.......404 Articulations of the Thorax, 98 Indicis,........403 Medii,........404 Prior Annularis,........403 Indicis,........- 403 Medii,.........404 Pronator Quadratus,.......391 Radii Teres,.......388 Psoas Magnus,........356 Parvus, -------- 357 Pterygoideus Externus, -......377 Internus,......- 378 Pubes,..........73 Pyramidalis,.........347 Pyriformis,........ 418 Quadratus Femoris,.......419 Lumborum,.......356 Radio-Carpal Articulations,......205 Radius,.........183 Rectus Abdominis, ......346 Capitis Anticus Major, - - - - - 370 __ — Minor, - - - - , 370 Posticus Major, :.-"'" 339 index. 489 Page Rectus Capitis Posticus Minor, - - - Vol. I. 340 Capitis Lateralis, - - - - . - - 370 Femoris, -._.....412 Rete Mucosum,........298 Rhomboideus Major, ------- 333 Minor, -.,-___ 333 Ribs,.........- 86 Cartilages of,.......92 Common points of resemblance between, - - 87 Differences in,.......89 Sacro-Lumbalis,........335 Salivary Glands,.......- 471 Sartorius, -"........411 Scalenus Anticus,.......371 Medius,........371 Posticus,.......371 Scaphoides, (Carpus,).......186 (Tarsus,).......237 Scapulo-Humeral Articulation,.....199 Sebaceous Organs of the Skin,.....306 Semimembranosus,.......421 Semispinalis Colli,.......338 Dorsi, _.----- 338 Semitendinosus,........421 Serratus Inferior Posticus,......333 Magnus,........36° Superior Posticus,......333 Shoulder,.........173 Articulation of,......193 Motions of, -.....- 197 Blade, -.......175 ......293 Skin, - - Skeleton Natural, General Anatomy of, - 1 Soft Palate, - -.......^ SoleUS' ." " - - 336 Spinalis Dorsi, - SPine' " " ; ". '.'.'. "- 54 Splenius, vol. I.*—3 ft 490 ,NDEX Sternum, ...--..- V.l. 1.^ Sterno-Cleido-Mastoideus, . - - - „ •, . 366 Hyoideus,.....- Thyroideus, - ^ Stylo-Glossus,..... 36g Hyoideus, ----- ggg Pharyngeus, - ] 36Q Subclavius,...... - 4/3 Sublingual Gland, ------ Submaxillary Gland, ----- c. u i • - - - - 384 Subscapularis, - Superior Maxillary Bones, - - - * Supinator Radii Brevis, - — Longus. 382 Supra Spinatus Scapulae, - Sutures, - Suture Coronal, - * Lambdoidal, - e ... , .....139 Sagittal, - i39 Squamous, - - - - Synovial Articular Capsules, - Tarso Metatarsal Articulations, - - _ . - - - 235 ^'T " ' " --- 440 TeCth; / f" " * " - - - - 448 Formation or, - t - - 442 Bicuspated, Cuspated, - - - - T . ... - 441 Incisor, .-- - 442 Molar, - - Temporal Bone, - - - - Temporalis, - ! " 327 Tendons, *"'"." 411 Tensor Fasciae vel Vaginae Femoris, - - *}* Teres Major, ... - I 383 Minor, ----- Texture and Organization of the Teeth, - * Thigh Bone, - - - - - J ; _" ; fn Motions of, - - Thorax, - 96 Articulations of, INDEX. 491 Page Thorax, Development of, ... - Vol. I. 94 Mechauism of,.......100 Thyreo-Hyoideus, .......366 Tibia, .........228 Tibialis Anticus,........422 Posticus,........430 Toes,..........244 Tongue,.........462 Tonsils,.........471 Trachelo-Mastoideus,.......337 Transversalis Abdominis,......346 Cervicis, ------- 327 Pedis, -......434 Trapezium, - - -......I87 Trapezius,........T 33° Trapezoides,........I8'" Triangularis Sterni,.......361 Triceps Extensor Cubiti,......386 Surse,........426 Trunk, .........42 Ulna,..........181 Unciforme, ........188 Unguiform Bones,.......129 Upper Extremities,.......17S Vertebral Column, Development of, - - - - 62 __ Ligaments of the Bodies of, - - 54 __ __ Processes of - -57 — Uses of,......64 Vertebrae, Lumbar, - fi° Motions peculiar to each class of, 67 - 412 Vastus Externus, - Internus,...... - 41S Voluntary Muscles, Mechanical shape, and arrangement of, 326 Wrist, Articulations of, - 204 Zygomaticus Major, - 574 Minor, 16 0 6 Ill IVNOIIVN 3NI3IQ1W JO A H V » • I 1 IVNOIIVN 1NI3I03W JO H«)in IVNOIIVN 3NI3I03W T OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL 1 /VI>A ! yj " u^^^> ? «W^k? - W\iM/ \ NOIIVN 3NI3I03W JO A 8 V H S I 1 IVNOIIVN ^7 f W/iW ■: W?M NOIIVN 3NI3I03W JO IDVIIM IVNOIIVN 3NI3I03W JO A IIV * 8 II IVNOIIVN 3NI3I03W JO All NOIIVN 3NI3I0 3W JO A»V»9I1 IVNOIIVN !NI3IQ1W JO AKYHII1 1VNOUYN 3 N I 3 I 0 3 W J 0 A « ^f f nin^A NATIONAL LIHAIY/aVMEDIClNtl___NATIONAL IIBRARY OF MEDICINE ___NATIONAL LI -H»W. o NLM010015374